Tue·Dec 17, 2024Tuesday·December 17, 2024

1. 01*

   Bottomoniumlike states in proton collisions: Fragmentation and resummation

   Francesco Giovanni Celiberto🇪🇸 · Gabriele Gatto🇮🇹

   We study the semi-inclusive hadroproduction of doubly bottomed tetraquarks ($X_{b\bar{b}q\bar{q}}$) as well as fully bottomed ones ($T_{4b}$), to which we collectively refer as "bottomoniumlike" states. We rely upon the variable-flavor number-scheme fragmentation at leading power, where a single parton perturbatively splits into the corresponding Fock state, which then hadronizes into the color-neutral, observed tetraquark. To this end, we build new sets of DGLAP/HF-NRevo consistent, hadron-structure oriented collinear fragmentation functions, which we name TQHL1.1 and TQ4Q1.1 parametrizations. They extend and supersede the corresponding 1.0 versions recently derived in previous works. The first family describes the fragmentation of doubly heavy tetraquarks and is based on an improved version of the Suzuki model for the heavy-quark channel. The second family depicts the fragmentation of fully heavy tetraquarks and embodies initial-scale inputs for gluon and heavy-quark channels, both of them calculated by the hands of potential nonrelativistic QCD. As a phenomenological application, we provide novel predictions for tetraquark-plus-jet high-energy distributions, computed within the NLL/NLO${}^{+}$ hybrid factorization from (sym)JETHAD, at 14 TeV and 100 TeV FCC.

   hep-phhep-exnucl-exnucl-thPRD(2025)·22 citations
2. 02*

   Born-Oppenheimer Renormalization group for High Energy Scattering: the Modified BFKL, or where did it all go?

   Haowu Duan🇺🇸 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱

   We continue exploring the Born-Oppenheimer renormalization group generating evolution in frequency of physical observables. In this paper we study the evolution of the total cross section for dilute-dilute scattering retaining only eikonal emissions. We derive and analyze the analog of the BFKL equation in this framework. The frequency evolution has a very strong effect on the solutions of the BO-BFKL equation, slowing down the evolution of the scattering amplitude in a spectacular fashion: the intercept of the Pomeron is decreased by about a factor of three relative to the canonical LO BFKL result. The anomalous dimension is also modified significantly - from the BFKL value of one it goes down to the negative value of $\approx -0.2$. Introducing saturation boundary as a proxy for the full saturation dynamics, we find that the dependence of the saturation momentum on rapidity $\eta$ becomes quite weak with $Q_s^2\sim e^{a{\bar{\alpha }}_s\eta }$ with $a\approx 0.784$ as opposed to the BFKL value $a=4.88$. Our results underscore the necessity to take into account the DGLAP effects in the high energy evolution. This is left for future work.

   hep-phhep-thnucl-th1 citation
3. 03*

   Coherent enhancement of QED cross-sections in electromagnetic backgrounds

   T. Heinzl🇬🇧 · B. King🇬🇧 · D. Liu🇬🇧

   We introduce form factors that relate the amplitude of a QED process in vacuum to its corresponding background-field process. The latter is characterised by a reduced S-matrix element where one or more photon field operators are replaced by classical background fields. In the associated Feynman diagram, external photon lines are supplanted with lines representing the c-number field. This modifies the cross section by factors proportional to powers of the Fourier amplitude of the classical field (and its complex conjugate). We demonstrate this explicitly by comparing different reaction channels of low-energy photon-photon scattering in a classical background. We find that background field cross sections typically undergo coherent enhancement and for some reaction channels display a more favourable scaling with centre-of-mass energy compared to the vacuum process. Similar coherent enhancement may be found for leading-order pair annihilation to one photon, but this competes with kinematic suppression. This suppression can be minimised by using an x-ray free electron laser as the classical background.

   hep-phPRD(2025)·9 citations
4. 04*

   Likelihood of a zero in the proton elastic electric form factor

   Peng Cheng🇨🇳 · Zhao-Qian Yao🇪🇸 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳

   Working with the $29$ available data on the ratio of proton electric and magnetic form factors, ${\mu }_p{G}_E^p(Q^2)/G_M^p(Q^2)$, and independent of any model or theory of strong interactions, we use the Schlessinger point method to objectively address the question of whether the ratio possesses a zero and, if so, its location. Our analysis predicts that, with 50% confidence, the data are consistent with the existence of a zero in the ratio on $Q^2\le 10.37$GeV${}^2$. The level of confidence increases to $99.9$\% on $Q^2\le 13.06$GeV${}^2$. Significantly, the likelihood that existing data are consistent with the absence of a zero in the ratio on $Q^2\le 14.49$GeV${}^2$ is $1/1$-million.

   hep-phhep-exhep-latnucl-ex+1PLB(2025)·11 citations
5. 05*

   Pretrained Event Classification Model for High Energy Physics Analysis

   Joshua Ho🇺🇸 · Benjamin Ryan Roberts🇺🇸 · Shuo Han🇺🇸 · Haichen Wang🇺🇸

   We introduce a foundation model for event classification in high-energy physics, built on a Graph Neural Network architecture and trained on 120 million simulated proton-proton collision events spanning 12 distinct physics processes. The model is pretrained to learn a general and robust representation of collision data using challenging multiclass and multilabel classification tasks. Its performance is evaluated across seven event classification tasks, which include new physics processes not encountered during pretraining as well as ATLAS Open Data to demonstrate generalizability across different simulation frameworks, from Delphes fast simulation to full ATLAS detector simulation. Fine-tuning the pretrained model significantly improves classification performance, particularly in scenarios with limited training data, demonstrating gains in both accuracy and computational efficiency. To investigate the underlying mechanisms behind these performance improvements, we employ a representational similarity evaluation framework based on Centered Kernel Alignment. This analysis reveals that encoder-stage representations of the fine-tuned model remain similar to those of the baseline, while intermediate graph processing layers diverge substantially, indicating that fine-tuning preserves general-purpose encoders while developing fundamentally different message-passing pathways to arrive at superior task performance.

   hep-phcs.LGJINST(2026)·13 citations
6. 06*

   Super-exponential Primordial Black Hole Production via Delayed Vacuum Decay

   Yanda Wu🇨🇳 · Stefano Profumo🇺🇸

   If a cosmological first-order phase transition occurs sufficiently slowly, delayed vacuum decay may lead to the formation of primordial black holes. Here we consider a simple model as a case study of how the abundance of the produced black holes depends on the model's input parameters. We demonstrate, using both numerical and analytical arguments and methods, that the black hole abundance is controlled by a double, ``super''-exponential dependence on the three-dimensional Euclidean action over temperature at its minimal value. We show that a modified expansion rate during the phase transition, such as one driven by an additional energy density component, leads to a weaker dependence on the underlying model parameters, but maintains the same super-exponential structure. We argue that our findings generalize to any framework of black hole production via delayed vacuum decay.

   hep-phastro-ph.COastro-ph.HEgr-qcPRD(2025)·7 citations
7. 07*

   Testing the Fifth Force on Lepton Spins through Neutrino Oscillations

   Rundong Fang🇨🇳 · Ji-Heng Guo🇨🇳 · Jia Liu🇨🇳 · Xiao-Ping Wang🇨🇳

   We investigate a fifth force mediated by a light vector boson that couples to lepton spins, characterized by axial-vector couplings to leptons and vector couplings to nucleons. This interaction generates a potential proportional to the inner product of the lepton spin vector and the nucleon-lepton relative velocity vector, a feature extensively explored with precision spin sensors. Employing weak symmetry, we show that left-handed charged lepton couplings naturally extend to left-handed neutrinos, enabling this fifth force to influence neutrino oscillations. For electron-nucleon couplings, we find that solar and reactor neutrino experiments provide comparable constraints to those from spin sensors and surpass them in the short-range fifth force region. For muon-nucleon couplings, neutrino oscillation experiments exclude the fifth force as a viable explanation for the muon $g-2$ anomaly in the context of a vector mediator, tightening the bounds by two orders of magnitude in coupling strength by solar and atmospheric neutrino data. Our results highlight the critical role of neutrino oscillations in probing fifth forces acting across all three generations of lepton spins.

   hep-phhep-exphysics.atom-phPRD(2025)·2 citations
8. 08*

   Revisiting constraints on proton PDFs from HERA DIS, Drell-Yan, W/Z Boson production, and projected EIC measurements

   Majid Azizi🇮🇷 · Maryam Soleymaninia🇮🇷 · Hadi Hashamipour🇮🇹 · Maral Salajegheh🇩🇪 · Hamzeh Khanpour🇮🇷 · Ulf-G. Meißner🇩🇪

   We present new parton distribution functions (PDFs) at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) in perturbative QCD, derived from a comprehensive global QCD analysis of high-precision data sets from combined HERA deep-inelastic scattering (DIS), the Tevatron, and the Large Hadron Collider (LHC). To improve constraints on quark flavor separation, we incorporate Drell-Yan pair production data, which provides critical sensitivity to the quark distributions. In addition, we include the latest W and Z boson production data from the CDF, D0, ATLAS, and CMS collaborations, further refining both quark and gluon distributions. Our nominal global QCD fit integrates these datasets and examines the resulting impact on the PDFs and their associated uncertainties. Uncertainties in the PDFs are quantified using the Hessian method, ensuring robust error estimates. Furthermore, we explore the sensitivity of the strong coupling constant, ${\alpha }_s(M_Z^2)$, and proton PDFs in light of the projected measurements from the Electron-Ion Collider (EIC), where improvements in precision are expected. The analysis also investigates the effects of inclusive jet and dijet production data, which provide enhanced constraints on the gluon PDF and ${\alpha }_s(M_Z^2)$.

   hep-phPRD(2025)·4 citations
9. 09*

   Relativistic effects in the strong and electromagnetic decays of $D^{\ast }$ meson

   Man Jia🇨🇳 · Wei Li🇨🇳 · Su-Yan Pei🇨🇳 · Xin-Yao Du🇨🇳 · Guo-Zhu Ning🇨🇳 · Guo-Li Wang🇨🇳

   In this paper, we solve the complete Salpeter equation and use the obtained relativistic wave function to calculate the strong and radiative electromagnetic decays of the $D^{\ast }$ meson. { We obtain the results $\Gamma (D^{\ast }(2007{)}^0\to D^0{\pi }^0)=34.6\mathrm{keV}$ and $\Gamma (D^{\ast }(2007{)}^0\to D^0\gamma )=19.4\mathrm{keV}$, and the estimated full width is $\Gamma (D^{\ast }(2007{)}^0)=54.0\mathrm{keV}$.} The focus of this study is on the relativistic corrections. In our method, the wave function of the $D$ meson is not a pure $S$-wave, but includes both a non-relativistic $S$-wave and a relativistic $P$-wave, while the wave function of the $D^{\ast }$ meson includes a non-relativistic $S$-wave as well as both relativistic $P$-wave and $D$-wave. Therefore, in this case, the decay $D^{\ast }\to D\gamma$ is not a non-relativistic $M1$ transition, but rather an $M1+E2+M3+E4$ decay. We find that in a strong decay $D^{\ast }\to D\pi$, the non-relativistic contribution is dominant, while in an electromagnetic decay $D^{\ast }\to D\gamma$, the relativistic correction is dominant.

   hep-phEPJC(2025)·5 citations
10. 10*

    Ultralight Dark Matter -- A Novel proposal

    T R Govindarajan🇮🇳

    A novel proposal is made to account for the dark matter component of the Universe. Ultralight dark matter with mass $\le \mathcal{O}(10^{-22})eV$ is one of the strong candidates for the missing mass which aids the formation of galaxies as well as holding them together. They are also known as fuzzy dark matter(FDM) which will come under Cold Dark matter. The question is what is this particle and its implications. How do we experimentally see it is an outstanding question. We propose to answer some of these questions with some evidences and the estimates.

    hep-phgr-qcAstrophys.Space Sci.Proc.(2025)·1 citation
11. 11*

    Detecting the Coupling of Axion Dark Matter to Neutron Spins at Spallation Sources via Rabi Oscillation

    Peter Fierlinger🇩🇪 · Jie Sheng🇨🇳 · Yevgeny V. Stadnik🇦🇺 · Chuan-Yang Xing🇨🇳

    We propose a novel detection method for axion dark matter using the Rabi oscillation of neutron spins in beam-based measurements. If axions couple to neutron spins, a background oscillating axion dark matter field would drive transitions between spin-up and spin-down neutron states in a magnetic field when the axion particle energy matches the energy gap between the spin states. The transition can be detected in a double-Stern-Gerlach-type apparatus, with the first splitter producing a pure spin-polarized neutron beam and the second splitter selecting spin-flipped signals. Our approach offers enhanced detection capability for axions within the $10^{-12}-10^{-10}$eV mass window with the capability to surpass the sensitivity of current laboratory experiments.

    hep-phastro-ph.COnucl-exphysics.ins-det3 citations
12. 12*

    Mass spectrum of the hidden-charm hybrid states via the QCD sum rules

    Zhi-Gang Wang🇨🇳

    In this work, we study the mass spectrum of the hidden-charm hybrid states with the $J^{PC}=0^{-+}$, $0^{++}$, $0^{--}$, $1^{++}$, $1^{+-}$, $1^{-+}$, $1^{--}$, $2^{-+}$ and $2^{++}$ via the QCD sum rules in a consistent way. We calculate the vacuum condensates up to dimensions-6 by taking account of both the leading order and next-to-leading order contributions, and take the energy scale formula $\mu =\sqrt{M_{X/Y/Z}^2-(2{\mathbb{M}}_c{)}^2}$ to choose the suitable energy scales of the QCD spectral densities, it is the first time to explore the energy scale dependence of the QCD sum rules for the hidden-charm hybrid states.

    hep-phPRD(2025)·15 citations
13. 13*

    Decays $\tau \to f_0(\pi ,K){\nu }_{\tau }$ and $\tau \to 3\pi {\nu }_{\tau }$ accounting for the contribution of $f_0(500)$

    M.K. Volkov🇷🇺 · A.A. Pivovarov🇷🇺 · K. Nurlan🇷🇺

    In the $U(3)\times U(3)$ quark NJL model, $\tau$ lepton decays with the production of scalar mesons $f_0(\pi ,K])$ and neutrinos are studied, where $f_0=f_0(500),f_0(980)$. It is shown that these decays mainly occur via contact channels and channels with axial-vector mesons $a_1$, $K_1(1270)$ and $K_1(1400)$. All mesons are considered as quark-antiquark states in this case. The obtained results can be considered as predictions for future experiments. The obtained estimates for the branching fractions of the $\tau \to {\pi }^{-}2{\pi }^0{\nu }_{\tau }$ decay taking into account the contributions of the $\rho \pi$ and $f_0(500)\pi$ states are in satisfactory agreement with experimental data.

    hep-phEPJA(2025)·3 citations
14. 14*

    Reevaluating the $\psi (4160)$ Resonance Parameter Using $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ Data in the Context of Unquenched Charmonium Spectroscopy

    Tian-Cai Peng🇨🇳 · Zi-Yue Bai🇨🇳 · Jun-Zhang Wang🇨🇳 · Xiang Liu🇨🇳

    A puzzling phenomenon, where the measured mass of the $\psi (4160)$ is pushed higher, presents a challenge to current theoretical models of hadron spectroscopy. This study suggests that the issue arises from analyses based on the outdated quenched charmonium spectrum. In the past two decades, the discovery of new hadronic states has emphasized the importance of the unquenched effect. Under the unquenched picture, six vector charmonium states-$\psi (4040)$, $\psi (4160)$, $\psi (4220)$, $\psi (4380)$, $\psi (4415)$, and $\psi (4500)$-are identified in the $4\sim 4.5$ GeV range, contrasting with the three states predicted in the quenched model. We reevaluate the resonance parameters of the $\psi (4160)$ using the di-muon invariant mass spectrum of $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ and unquenched charmonium spectroscopy. Our analysis finds the $\psi (4160)$ mass at $4145.76\pm 4.48$ MeV, indicating previous overestimations. This conclusion is supported by analyzing $e^{+}{e}^{-}\to D_s{\bar{D}}_s^{\ast }$. Our findings have significant implications for both hadron spectroscopy and search for new physics signals by $R_K$.

    hep-phhep-exPRD(2025)·6 citations
15. 15*

    Study on the structure of the $Z_c(3900)$ state

    Yan Ma🇨🇳 · De-Shun Zhang🇨🇳 · Cheng-Qun Pang🇨🇳 · Zhi-Feng Sun🇨🇳

    In this work, we studied the $Z_c(3900)$ state within the framework of effective field theory. We firstly show the construction of the Lagrangian describing meson-meson-meson and meson-diquark-diquark interactions. By using the Feynman rule, we calculate the effective potentials corresponding to the coupled channels of $D{\bar{D}}^{\ast }/D^{\ast }\bar{D}$ and $S_{cq}{\bar{A}}_{cq}/A_{cq}{\bar{S}}_{cq}$ with $S_{cq}$ ($A_{cq}$) the scalar (axial vector) diquark composed of $c$ and $q$ quarks. After solving the Bethe-Salpeter equation of the on-shell parametrized form and compare our numerical results with the experimental mass and width of $Z_c(3900)$, we find that the $Z_c(3900)$ state can be explained as the mixture of $D{\bar{D}}^{\ast }/D^{\ast }\bar{D}$ and $S_{cq}{\bar{A}}_{cq}/A_{cq}{\bar{S}}_{cq}$ components.

    hep-phhep-ex2 citations
16. 16*

    Point Cloud Deep Learning Methods for Particle Shower Reconstruction in the DHCAL

    Maryna Borysova🇮🇱 · Shikma Bressler🇮🇱 · Eilam Gross🇮🇱 · Nilotpal Kakati🇮🇱 · Darina Zavazieva🇮🇱

    Precision measurement of hadronic final states presents complex experimental challenges. The study explores the concept of a gaseous Digital Hadronic Calorimeter (DHCAL) and discusses the potential benefits of employing Graph Neural Network (GNN) methods for future collider experiments. In particular, we use GNN to describe calorimeter clusters as point clouds or a collection of data points representing a three-dimensional object in space. Combined with Graph Attention Transformers (GATs) and DeepSets algorithms, this results in an improvement over existing baseline techniques for particle identification and energy resolution. We discuss the challenges encountered in implementing GNN methods for energy measurement in digital calorimeters, e.g., the large variety of hadronic shower shapes and the hyper-parameter optimization. We also discuss the dependency of the measured performance on the angle of the incoming particle and on the detector granularity. Finally, we highlight potential future directions and applications of these techniques.

    hep-phEPJ Web Conf.(2025)·0 citations
17. 17*

    Toponium: the smallest bound state and simplest hadron in quantum mechanics

    Jing-Hang Fu🇨🇳 · Yu-Ji Li🇨🇳 · Hui-Min Yang🇨🇳 · Yu-Bo Li🇨🇳 · Yu-Jie Zhang🇨🇳 · Cheng-Ping Shen🇨🇳

    We explore toponium, the smallest known quantum bound state of a top quark and its antiparticle, bound by the strong force. With a Bohr radius of $8\times 10^{-18}$~m and a lifetime of $2.5\times 10^{-25}$~s, toponium uniquely probes microphysics. Unlike all other hadrons, it is governed by ultraviolet freedom. This distinction offers novel insights into quantum chromodynamics. Our analysis reveals a toponium signal exceeding $5\sigma$ in the distribution of the cross section ratio between $e^{+}{e}^{-}\to b\bar{b}$ and $e^{+}{e}^{-}\to q\bar{q}$ ($q=b,c,s,d,u$), based on 400~fb${}^{-1}$ of data collected at $\sqrt{s}\approx 341\mathrm{GeV}$. This discovery enables a top quark mass measurement with an uncertainty reduced by a factor of ten compared to current precision levels. Moreover, this method improves the systematic uncertainty by at least a factor of 2.7 compared to any other possible methods.

    hep-phhep-exPRD(2025)·23 citations
18. 18*

    C-Code Reader of Form Factors

    Ahmed Rashed🇺🇸

    The process ${\Lambda }_b\to {\Lambda }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ serves as a tool for exploring new physics, with contributions from scalar, vector, and tensor hadronic currents in various models. These form factors are derived from the quark model or lattice QCD. This work introduces a C-code for efficiently reading lattice QCD form factors for these currents, significantly outperforming a previous Mathematica-based approach, with a speed improvement of over 64 times per data point. The code, available on GitHub $(https://github.com/darkfiresmith96/Lattic{e}_{Q}CD)$, also features a web interface for user inputs.

    hep-ph0 citations
19. 19*

    Constraints on Dark Photon and Dark $Z$ Model Parameters in the $B$ and $K$ Meson Decays

    Ahmed Rashed🇺🇸

    The study investigates flavor-changing neutral current (FCNC) decays of $B$ and $K$ mesons in the context of a dark $U(1{)}_D$ model with a dark photon/dark $Z$ mass between 10 MeV and 2 GeV. While the model improves the fit to certain decay distributions, such as $B\to K^{(\ast )}{\ell }^{+}{\ell }^{-}$ and $B_s\to \varphi {\mu }^{+}{\mu }^{-}$, it is ruled out by stringent experimental constraints, including atomic parity violation, $K^{+}\to {\mu }^{+}+\text{invisible}$, and $B_s-{\overline{B}}_s$ mixing. To address these constraints, the model is extended with three modifications; allowing additional invisible decays of $Z_D$, introducing a direct vector coupling of $Z_D$ to muons, and including a direct coupling of $Z_D$ to both muons and electrons, with fine-tuning to cancel the mixing-induced coupling to electrons. Among these extensions, only the third scenario, involving fine-tuned electron coupling, remains consistent with all experimental constraints.

    hep-ph0 citations
20. 20*

    Strangeonium spectrum with the screening effects and interpretation of $h_1(1911)$ and $X(2300)$ observed by BESIII

    Wei Hao🇨🇳 · M. Atif Sultan🇨🇳 · Li-Juan Liu🇨🇳 · En Wang🇨🇳

    Motivated by two news states $h_1(1911)$ and $X(2300)$ observed by BESIII, we have investigated the mass spectrum and the strong decay properties of the strangeonium mesons within the modified Godfrey-Isgur model by considering the screening effects. We have determined the free parameters using the masses and widths of the well established $s\bar{s}$ states $\varphi (1020)$, $\varphi (1680)$, $h_1(1415)$, $f_2^{\prime }(1525)$, and ${\varphi }_3(1850)$. According to our results, $h_1(1911)$ and $X(2300)$ could be well explained as states $h_1(2^1{P}_1)$ and $h_1(3^1{P}_1)$ $s\bar{s}$ states, respectively. Meanwhile, the possible assignments of $X(2000)$, ${\eta }_2(1870)$, and $\varphi (2170)$ as $3^3{S}_1$, $1^1{D}_2$, and $2^3{D}_1$ are also discussed. Furthermore, the masses and widths of the $2S$, $3S$, $1P$, $2P$, $3P$, $1D$, and $2D$ $s\bar{s}$ states are also given and compared with various theoretical predictions, which is helpful for the observations and confirmations of these states in future.

    hep-phPRD(2025)·5 citations
21. 21*

    Investigating triply heavy tetraquark states through QCD sum rules

    Wen-Shuai Zhang🇨🇳 · Liang Tang🇨🇳

    We apply the method of QCD sum rules to study the \(QQ\bar{Q}\bar{q}\) and \(QQ\bar{Q}\bar{s}\) tetraquark states, where $Q=c,b$ and $q=u,d$, with the quantum number \(J^P = 0^{+}\). We consider the contributions of vacuum condensates up to dimension-9 in the operator product expansion, and use the energy scale formula \(\mu = \sqrt{M_{X}^2 - (i\mathbb{M}_c + j\mathbb{M}_b)^2} - k\mathbb{M}_s\) to determine the optimal energy scales for the QCD spectral densities. Our results indicate that triply charm tetraquark states \(cc\bar{c}\bar{q}\) and \(cc\bar{c}\bar{s}\) have masses in the ranges of $5.38-5.84\text{GeV}$ and $5.66-6.16\text{GeV}$, respectively. In the bottom sector, triply bottom tetraquark states \(bb\bar{b}\bar{q}\) and \(bb\bar{b}\bar{s}\) have masses in the ranges of $14.89-15.55\text{GeV}$ and $14.95-15.66\text{GeV}$, respectively. This study could help distinguish these states in upcoming high-energy nuclear and particle experiments.

    hep-phNPA(2025)·14 citations
22. 22*

    Charmful two-body ${\Omega }_b$ decays in the light-front quark model

    Yan-Li Wang🇨🇳 · Yu-Kuo Hsiao🇨🇳 · Kai-Lei Wang🇨🇳 · Chong-Chung Lih🇨🇳

    We investigate the singly and doubly charmful two-body ${\Omega }_b^{-}$ decays using the light-front quark model. Our findings reveal that most branching fractions calculated in this study, such as $\mathcal{B}({\Omega }_b^{-}\to {\Xi }^{-}{D}^0,{\Xi }^{-}{D}^{\ast 0})$, can be ten to one hundred times larger than those reported in previous calculations. Additionally, we interpret the ratio $\mathcal{B}({\Omega }_b^{-}\to {\Omega }^{-}J/\psi )/\mathcal{B}({\Omega }_b^{-}\to {\Omega }^{-}{\eta }_c)\simeq 3.4$ within the helicity framework. While the decay involving external $W$-boson emission appears to be suppressed by the $b\to u\bar{c}s$ weak transition, it still yields a significant branching fraction. For instance, $\mathcal{B}({\Omega }_b^{-}\to {\Xi }^0{D}_s^{\ast -})=(5.9-14.2)\times 10^{-5}$, $\mathcal{B}({\Omega }_b^{-}\to {\Xi }^{\ast 0}{D}_s^{-})=(6.7-12.1)\times 10^{-5}$, and $\mathcal{B}({\Omega }_b^{-}\to {\Xi }^{\ast 0}{D}_s^{\ast -})=(12.8-26.7)\times 10^{-5}$, with values reaching as large as $10^{-4}$. These predictions are well within the experimental reach of LHCb.

    hep-phhep-exPRD(2025)·6 citations
23. 23*

    Non-equilibrium dynamics of Goldstone excitation from holography

    Pei Zheng🇨🇳 · Yidian Chen🇨🇳 · Danning Li🇨🇳 · Mei Huang🇨🇳 · Yuxin Liu🇨🇳

    By using the holographic approach, we investigate the interplay between the order parameter and Goldstone modes in the real-time dynamics of the chiral phase transition. By quenching the system to a different thermal bath and obtaining different kinds of initial states, we solve the real-time evolution of the system numerically. Our main focus is on studying far-from equilibrium dynamics of strongly-coupled system and universal scaling behaviors related to such dynamics. The most striking observation is that an additional prethermalization stage emerges at non-critical temperature after introducing the Goldstone modes, which is not reported in any previous studies. Some basic properties related to this additional prethermalization stage have been discussed in detail. More interestingly, we also report a new scaling relation describing non-equilibrium evolution at non-critical temperature. This additional universal behavior indicates the appearance of a non-thermal fixed point in the dynamical region.

    hep-phJHEP(2025)·4 citations
24. 24*

    Superradiant Neutrino Lasers from Radioactive Condensates

    B.J.P Jones🇺🇸 · J.A. Formaggio🇺🇸

    Superradiance emerges from collective spontaneous emission in optically pumped gases, and is characterized by photon emission enhancements of up to $\frac{1}{4}{N}^2$ in an $N$ atom system. The gain mechanism derives from correlations developed within the decay medium rather than from stimulated emission as in lasing, so analog of this process should be possible for fermionic final states. We introduce here the concept of superradiant neutrino emission from a radioactive Bose Einstein condensate, which can form the basis for a superradiant neutrino laser. A plausible experimental realization based on a condensate of electron-capture isotope ${}^{83}$Rb could exhibit effective radioactive decay rates accelerated from 86.2 days to minutes in viably sized rubidium condensates of $10^6$ atoms.

    hep-phquant-phPRL(2025)·6 citations
25. 25*

    Quantum Decoherence at ESSnuSB Experiment

    ESSnuSB: M. Ghosh🇭🇷

    In this proceedings we study the sensitivity of the ESSnuSB experiment to probe quantum decoherence. ESSnuSB is a future long-baseline neutrino oscillation experiment which aims to measure ${\delta }_{\mathrm{CP}}$ by probing the second oscillation maximum. Using the open quantum system formalism for decoherence, we have shown that the sensitivity of ESSnuSB to constrain the decoherence parameters is better than MINOS but comparable to DUNE. We have also shown that the CP measurement capability of ESSnuSB is robust in presence of decoherence.

    hep-phhep-exPoS(2025)·0 citations
26. 26*

    Quark and gluon entanglement in the proton based on a light-front Hamiltonian

    Chen Qian🇨🇳 · Siqi Xu🇨🇳 · Yang-Guang Yang🇨🇳 · Xingbo Zhao🇨🇳

    Given that the wave function of a proton can be derived relativistically and nonperturbatively from a light-front quantized Hamiltonian, investigating the quantum correlation between quarks and gluons offers a novel perspective on the internal structure of partons within a proton. In this work, we address this topic by computing the spin and longitudinal momentum entanglement of each parton inside the proton. The utilized wave functions are generated using Basis Light-front Quantization (BLFQ), incorporating both the valence quarks and one dynamical gluon Fock sectors, $|qqq⟩$ and $|qqq⟩+|qqqg⟩$. Our calculations indicate that the dynamical gluon significantly enhances entanglement among the proton's partons. Additionally, we examine the spin entanglement of quarks and gluons at fixed values of longitudinal momentum fraction, revealing that the presence of a gluon may amplify the informational exchanges between quarks. Finally, these findings suggest the potential for experimental verification of the entanglement between partons by measuring parton helicity distributions in the proton.

    hep-phquant-phPRD(2025)·5 citations
27. 27*

    Probing sub-TeV Higgsinos aided by a ML-based top tagger in the context of Trilinear RPV SUSY

    Rajneil Baruah🇮🇳 · Arghya Choudhury🇮🇳 · Kirtiman Ghosh🇮🇳 · Subhadeep Mondal🇮🇳 · Rameswar Sahu🇮🇳

    Probing higgsinos remains a challenge at the LHC owing to their small production cross-sections and the complexity of the decay modes of the nearly mass degenerate higgsino states. The existing limits on higgsino mass are much weaker compared to its bino and wino counterparts. This leaves a large chunk of sub-TeV supersymmetric parameter space unexplored so far. In this work, we explore the possibility of probing higgsino masses in the 400 - 1000 GeV range. We consider a simplified supersymmetric scenario where R-Parity is violated through a baryon number violating trilinear coupling. We adopt a machine learning-based top tagger to tag the boosted top jets originating from higgsinos, and for our collider analysis, we use a BDT classifier to discriminate signal over SM backgrounds. We construct two signal regions characterized by at least one top jet and different multiplicities of $b$-jets and light jets. Combining the statistical significance obtained from the two signal regions, we show that higgsino mass as high as 925 GeV can be probed at the high luminosity LHC.

    hep-phPRD(2025)·5 citations
28. 28*

    Searching for neutrino self-interactions at future muon colliders

    Hongkai Liu🇺🇸 · Daiki Ueda🇮🇱

    Multi-TeV muon colliders offer a powerful means of accessing new physics coupled to muons while generating clean and intense high-energy neutrino beams via muon decays. We study a fixed-target experiment leveraging the neutrino beams and a forward detector pointing at the interaction point of the muon collider. The sensitivity to neutrino self-interactions is analyzed as a feasibility study, focusing on the leptonic scalar $\varphi$ exclusively coupled to the Standard Model neutrinos. Our work shows that projections from both the main and forward detectors can enhance the existing limits by two orders of magnitude, surpassing other future experiments.

    hep-phhep-exPLB(2025)·7 citations
29. 29*

    The causal structure of the quark propagator

    Jan M. Pawlowski🇩🇪 · Jonas Wessely🇩🇪

    We study the causal structure of the quark propagator with the spectral DSE. The spectral gap equation is solved with the input of the spectral representation of the gluon and a causal STI-construction for the quark-gluon vertex. The latter includes a potential infrared enhancement of the vertex strength of the classical tensor structure that accommodates for the physical strength of chiral symmetry breaking. We find a critical vertex strength, below which the quark has a Källén-Lehmann representation. While the nature of the first singularity does not change above the critical strength, we find that the quark propagator features at least two additional pairs of complex conjugate poles that are located approximately at the sum of quark pole mass and peak position of the quark-gluon coupling. These additional poles lead to violations of causality, if they persist in $S$-matrix elements. While the vertex strength of the classical tensor structure in full QCD is below the critical one, that of commonly used vertex models, which rely solely on the classical vertex structure, is typically above it. Finally, we discuss how these additional poles could be avoided in full QCD, where part of chiral symmetry breaking is generated by the other tensor structures in the quark-gluon vertex.

    hep-phhep-thnucl-thEPJC(2025)·11 citations
30. 30*

    Accurate Surrogate Amplitudes with Calibrated Uncertainties

    Henning Bahl🇩🇪 · Nina Elmer🇩🇪 · Luigi Favaro🇧🇪 · Manuel Haußmann🇩🇰 · Tilman Plehn🇩🇪 · Ramon Winterhalder🇮🇹

    Neural networks for LHC physics have to be accurate, reliable, and controlled. Using neural surrogates for the prediction of loop amplitudes as a use case, we first show how activation functions are systematically tested with Kolmogorov-Arnold Networks. Then, we train neural surrogates to simultaneously predict the target amplitude and an uncertainty for the prediction. We disentangle systematic uncertainties, learned by a well-defined likelihood loss, from statistical uncertainties, which require the introduction of Bayesian neural networks or repulsive ensembles. We test the coverage of the learned uncertainties using pull distributions to quantify the calibration of cutting-edge neural surrogates.

    hep-phSciPost Phys.Core(2025)·33 citations
31. 31*

    Extrapolating Jet Radiation with Autoregressive Transformers

    Anja Butter🇩🇪 · François Charton🇫🇷 · Javier Mariño Villadamigo🇩🇪 · Ayodele Ore🇩🇪 · Tilman Plehn🇩🇪 · Jonas Spinner🇩🇪

    Generative networks are an exciting tool for fast LHC event fixed number of particles. Autoregressive transformers allow us to generate events containing variable numbers of particles, very much in line with the physics of QCD jet radiation, and offer the possibility to generalize to higher multiplicities. We show how transformers can learn a factorized likelihood for jet radiation and extrapolate in terms of the number of generated jets. For this extrapolation, bootstrapping training data and training with modifications of the likelihood loss can be used.

    hep-phcs.LGSciPost Phys.(2026)·12 citations
32. 32*

    Predictions for dimuon production in high-energy neutrino-proton collisions using the color dipole model

    Caetano Ternes🇧🇷 · Daniel Almeida Fagundes🇧🇷 · Edgar Huayra🇧🇷 · Emmanuel G. de Oliveira🇧🇷

    Interactions of high-energy neutrinos with matter can be studied through the angular separation observed in dimuon production, an observable particularly sensitive to the transverse momentum dynamics of partons. In this work, we develop a Monte Carlo event generator based on the color dipole model, interfaced with Pythia8 for parton showering and hadronization simulations, to predict dimuon production cross sections in neutrino-proton collisions at energies relevant to IceCube and future detectors. The color dipole formalism generates larger transverse momentum compared to standard Pythia predictions, enhancing the yield of angularly separated high-energy muons.

    hep-phJHEP(2025)·1 citation
33. 33*

    Anisotropic jet broadening and jet shape

    Weiyao Ke🇨🇳 · John Terry🇺🇸 · Ivan Vitev🇺🇸

    In this paper, we explore the use of jet substructure as a way of probing phenomena which break the isotropic behavior of jets, such as jet propagation through an anisotropically flowing quark-gluon plasma or spin correlations. We introduce two novel observables for this purpose: the azimuthal-dependent jet broadening and the azimuthal-dependent jet shape, which generalize the traditional isotropic substructure studies. Using Soft-Collinear Effective Theory, we explicitly calculate the jet functions associated with these observables with a standard jet axis and with a Winner-Take-All jet axis in both the resummed and fixed order limits. While our analysis first and foremost establishes the formalism for the azimuthal-dependent jet substructure, it also brings to light new results for jet substructure in the azimuthally integrated case, such as the semi-inclusive jet function and the exclusive jet shape for the Winner-Take-All axis, and the jet broadening in the fixed order region. As an illustrative example for the new formalism we demonstrate that the azimuthal-dependent jet broadening can be used as a direct probe of the transversity parton distribution function in deep inelastic scattering.

    hep-phhep-exnucl-exnucl-thJHEP(2025)·9 citations
34. 34*

    Stability of Superconducting Strings

    Keisuke Harigaya🇺🇸 · Xuce Niu🇺🇸 · Wei Xue🇺🇸 · Fengwei Yang🇺🇸

    We investigate the stability of superconducting strings as bound states of strings and fermion zero modes at both the classical and quantum levels. The dynamics of these superconducting strings can result in a stable configuration, known as a vorton. We mainly focus on global strings, but the majority of the discussion can be applied to local strings. Using lattice simulations, we study the classical dynamics of superconducting strings and confirm that they relax to the vorton configuration through Nambu-Goldstone boson radiation, with no evidence of over-shooting that would destabilize the vorton. We explore the tunneling of fermion zero modes out of the strings. Both our classical analysis and quantum calculations yield consistent results: the maximum energy of the zero mode significantly exceeds the fermion mass, in contrast to previous literature. Additionally, we introduce a world-sheet formalism to evaluate the decay rate of zero modes into other particles, which constitute the dominant decay channel. We also identify additional processes that trigger zero-mode decay due to non-adiabatic changes of the string configuration. In these decay processes, the rates are suppressed by the curvature of string loops, with exponential suppression for large masses of the final states. We further study the scattering with light charged particles surrounding the string core produced by the zero-mode current and find that a wide zero-mode wavefunction can enhance vorton stability.

    hep-phastro-ph.COhep-thJHEP(2025)·3 citations
35. 35*

    Axion strings from string axions

    James M. Cline🇨🇦 · Christos Litos🇺🇸 · Wei Xue🇺🇸

    A favored scenario for axions to be dark matter is for them to form a cosmic string network that subsequently decays, allowing for a tight link between the axion mass and relic abundance. We discuss an example in which the axion is protected from quantum gravity effects that would spoil its ability to solve the strong CP problem: namely a string theoretic axion arising from gauge symmetry in warped extra dimensions. Axion strings arise following the first-order Randall-Sundrum compactification phase transition, forming at the junctions of three bubbles during percolation. Their tensions are at the low scale associated with the warp factor, and are parametrically smaller than the usual field-theory axion strings, relative to the scale of their decay constant. Simulations of string network formation by this mechanism must be carried out to see whether the axion mass-relic density relation depends on the new parameters in the theory.

    hep-phastro-ph.COhep-thPRD(2025)·7 citations
36. 36*

    Searching for hadronic scale baryonic and dark forces at $(g-2{)}_{\mu }$'s lattice-vs-dispersion front

    Kaustubh Agashe🇺🇸 · Abhishek Banerjee🇺🇸 · Minuyan Jiang🇩🇪 · Shmuel Nussinov🇮🇱 · Kushan Panchal🇺🇸 · Srijit Paul🇺🇸 · Gilad Perez🇮🇱 · Yotam Soreq🇮🇱

    The anomalous magnetic moment of the muon ($a_{\mu }$) provides a stringent test of the quantum nature of the Standard Model (SM) and its extensions. To probe beyond the SM physics, one needs to be able to subtract the SM contributions, which consists of a non-perturbative part, namely, the hadronic vacuum polarization (HVP) of the photon. The state of the art is to predominantly use two different methods to extract this HVP: lattice computation, and dispersion relation-based, data-driven method. Thus one can construct different forms of the ``$a_{\mu }$ test" which compares the precise measurement of $a_{\mu }$ to its theory prediction. Additionally, this opens the possibility for another subtle test, where these two ``theory" predictions themselves are compared against each other, which is denoted as the ``HVP-test". This test is particularly sensitive to hadronic scale new physics. Therefore, in this work, we consider a SM extension consisting of a generic, light $\sim (100\mathrm{MeV}-1\mathrm{GeV})$ vector boson and study its impact on both tests. We develop a comprehensive formalism for this purpose. We find that in the case of data-driven HVP being used in the $a_{\mu }$ test, the new physics contributions effectively cancels for a flavor-universal vector boson. As an illustration of these general results, we consider two benchmark models: i)~the dark photon ($A^{\prime }$) and ii)~a gauge boson coupled to baryon-number ($B$). Using a combination of these tests, we are able to constrain the parameter space of $B$ and $A^{\prime }$, complementarily to the existing limits. As a spin-off, our preliminary analysis of the spectrum of invariant mass of $3\pi$ in events with ISR at the $B-$ factories (BaBar, Belle) manifests the value of such a study in searching for $B\to 3\pi$ decay, thus motivating a dedicated search by experimental collaborations.

    hep-phhep-exJHEP(2025)·1 citation
37. 37*

    Minimal Dirac seesaw dark matter

    Zafri Ahmed Borboruah🇮🇳 · Debasish Borah🇮🇳 · Lekhika Malhotra🇮🇳 · Utkarsh Patel🇮🇳

    We propose a minimal Type-I Dirac seesaw which accommodates a thermal scalar dark matter (DM) candidate protected by a charge conjugation symmetry in dark sector $C_{\mathrm{dark}}$, without introducing any additional field beyond the ones taking part in the seesaw. A $Z_4$ symmetry is introduced to realise the tree level Dirac seesaw while the Majorana mass terms are prevented by an unbroken global lepton number symmetry. While the spontaneous $Z_4$ breaking together with electroweak symmetry breaking lead to the generation of light Dirac neutrino mass, it also results in the formation of domain walls. These cosmologically catastrophic walls can be made to annihilate away by introducing bias terms while also generating stochastic gravitational waves (GW) within reach of near future experiments like \texttt{LISA}, \texttt{BBO}, $\mu$-\texttt{ARES} etc. The scalar DM parameter space can be probed at direct and indirect search experiments. Light Dirac neutrinos also enhance the relativistic degrees of freedom $N_{\mathrm{eff}}$ within reach of future cosmic microwave background (CMB) experiments. The model can also explain the observed baryon asymmetry via Dirac leptogenesis.

    hep-phastro-ph.COPRD(2025)·21 citations
38. 38*

    A Guide to Functional Methods Beyond One-Loop Order

    Javier Fuentes-Martín🇪🇸 · Adrián Moreno-Sánchez🇪🇸 · Ajdin Palavrić🇨🇭 · Anders Eller Thomsen🇨🇭

    Functional methods can be applied to the quantum effective action to efficiently determine counterterms and matching conditions for effective field theories. We extend the toolbox to two-loop order and beyond and show how to evaluate the expansion of the path integral in a manifestly gauge-covariant manner. We also generalize the method to theories with mixed spin statistics and prove the validity of the hard-region matching formula to all loop orders. The methods are exemplified with a two-loop matching calculation of the Euler-Heisenberg Lagrangian resulting from decoupling the electron in QED.

    hep-phhep-thJHEP(2025)·29 citations
39. 39*

    Heavy Neutral Leptons without Prejudice

    Nicolás Bernal🇦🇪 · Kuldeep Deka🇦🇪 · Marta Losada🇦🇪

    Heavy Neutral Leptons (HNLs) provide a compelling extension to the Standard Model, addressing the neutrino masses, baryogenesis, and dark matter problems. We perform a model-independent collider study, decoupling the active-sterile mixing angle ($V$) from the Yukawa coupling ($y$), and explore sensitivities at the HL-LHC for prompt and displaced decays. We also consider the possibility of HNLs being long-lived particles decaying in far detectors as FASER. In addition, we study the expected reach at FCC-ee for the prompt and displaced cases. For zero mixing, FCC-ee and HL-LHC sensitivities to $y$ are comparable, with Higgs width measurements imposing the strongest constraints. With non-zero mixing, sensitivities are dominated by $V$, significantly constraining parameter space. This work highlights the importance of precision Higgs studies and displaced searches in probing HNLs at current and future colliders.

    hep-phhep-exPRD(2025)·2 citations
40. 40*

    QCD factorization with multihadron fragmentation functions

    T. C. Rogers🇺🇸 · M. Radici🇮🇹 · A. Courtoy🇲🇽 · T. Rainaldi🇺🇸

    Important aspects of QCD factorization theorems are the properties of the objects involved that can be identified as universal. One example is that the definitions of parton densities and fragmentation functions for different types of hadrons differ only in the identity of the nonperturbative states that form the matrix elements, but are otherwise the same. This leads to independence of perturbative calculations on nonperturbative details of external states. It also lends support to interpretations of correlation functions as encapsulations of intrinsic nonperturbative properties. These characteristics have usually been presumed to still hold true in fragmentation functions even when the observed nonperturbative state is a small-mass cluster of $n$ hadrons rather than simply a single isolated hadron. However, the multidifferential aspect of cross sections that rely on these latter types of fragmentation functions complicates the treatment of kinematical approximations in factorization derivations. That has led to recent claims that the operator definitions for fragmentation functions need to be modified from the single hadron case with nonuniversal prefactors. With such concerns as our motivation, we retrace the steps for factorizing the unpolarized semi-inclusive $e^{+}{e}^{-}$ annihilation cross section and confirm that they do apply without modification to the case of a small-mass multihadron observed in the final state. In particular, we verify that the standard operator definition from single hadron fragmentation, with its usual prefactor, remains equally valid for the small-mass $n$-hadron case with the same hard parts and evolution kernels, whereas the more recently proposed definitions with nonuniversal prefactors do not. Our results reaffirm the reliability of most past phenomenological applications of dihadron fragmentation functions.

    hep-phhep-exnucl-exnucl-thPRD(2025)·18 citations
41. 41*

    Observations of the singly Cabibbo-suppressed decays ${\Xi }_c^{+}\to p{K}_S^0$, ${\Xi }_c^{+}\to \Lambda {\pi }^{+}$, and ${\Xi }_c^{+}\to {\Sigma }^0{\pi }^{+}$ at Belle and Belle II

    Belle · Belle II Collaborations: I. Adachi · L. Aggarwal · N. Akopov · M. Alhakami · A. Aloisio · N. Althubiti · N. Anh Ky · D. M. Asner · H. Atmacan · T. Aushev · V. Aushev and 334 other authors

    Using data samples of 983.0~$\mathrm{f}{\mathrm{b}}^{-1}$ and 427.9~$\mathrm{f}{\mathrm{b}}^{-1}$ accumulated with the Belle and Belle~II detectors operating at the KEKB and SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ colliders, singly Cabibbo-suppressed decays ${\Xi }_c^{+}\to p{K}_S^0$, ${\Xi }_c^{+}\to \Lambda {\pi }^{+}$, and ${\Xi }_c^{+}\to {\Sigma }^0{\pi }^{+}$ are observed for the first time. The ratios of branching fractions of ${\Xi }_c^{+}\to p{K}_S^0$, ${\Xi }_c^{+}\to \Lambda {\pi }^{+}$, and ${\Xi }_c^{+}\to {\Sigma }^0{\pi }^{+}$ relative to that of ${\Xi }_c^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}$ are measured to be \begin{equation} \frac{{\cal B}(\Xi_c^+ \to pK_S^0)}{{\cal B}(\Xi_c^{+} \to \Xi^{-} \pi^+ \pi^+)} = (2.47 \pm 0.16 \pm 0.07)\% \notag, \end{equation} \begin{equation} \frac{{\cal B}(\Xi_c^+ \to \Lambda \pi^+)}{{\cal B}(\Xi_c^{+} \to \Xi^{-} \pi^+ \pi^+)} = (1.56 \pm 0.14 \pm 0.09)\% \notag, \end{equation} \begin{equation} \frac{{\cal B}(\Xi_c^+ \to \Sigma^0 \pi^+)}{{\cal B}(\Xi_c^{+} \to \Xi^{-} \pi^+ \pi^+)} = (4.13 \pm 0.26 \pm 0.22)\% \notag. \end{equation} Multiplying these values by the branching fraction of the normalization channel, $\mathcal{B}({\Xi }_c^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+})=(2.9\pm 1.3)\%$, the absolute branching fractions are determined to be \begin{equation} {\cal B}(\Xi_c^{+} \to p K_{S}^{0}) = (7.16 \pm 0.46 \pm 0.20 \pm 3.21) \times 10^{-4} \notag, \end{equation} \begin{equation} {\cal B}(\Xi_c^{+} \to \Lambda \pi^+) = (4.52 \pm 0.41 \pm 0.26 \pm 2.03) \times 10^{-4} \notag, \end{equation} \begin{equation} {\cal B}(\Xi_c^{+} \to \Sigma^0 \pi^+) = (1.20 \pm 0.08 \pm 0.07 \pm 0.54) \times 10^{-3} \notag. \end{equation} The first and second uncertainties above are statistical and systematic, respectively, while the third ones arise from the uncertainty in $\mathcal{B}({\Xi }_c^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+})$.

    ↳ hep-exhep-phJHEP(2025)·16 citations
42. 42*

    Designing weight regularizations based on Lefschetz thimbles to stabilize complex Langevin

    Kirill Boguslavski🇦🇹 · Paul Hotzy🇦🇹 · David I. Müller🇦🇹

    The complex Langevin (CL) method shows significant potential in addressing the numerical sign problem. Nonetheless, it often produces incorrect results when used without any stabilization techniques. Leveraging insights from previous research that links Lefschetz thimbles and CL, we explore a strategy to regularize the CL method to address this issue of incorrect convergence. Specifically, we implement weight regularizations inspired by the associated Lefschetz thimble structure and correct the bias to retrieve the correct results of the original theory. We demonstrate the effectiveness of this approach by solving the SU(N) Polyakov chain model and various scalar models, including the cosine model and the one-link model, across a broad range of couplings where the CL method previously failed. We also discuss the potential application of these insights to gauge theories in practical scenarios.

    ↳ hep-lathep-phPoS(2025)·3 citations
43. 43*

    Isospectral local Hermitian theory for the $\mathcal{P}\mathcal{T}$-symmetric $i{\varphi }^3$ quantum field theory

    Yi-Da Li🇨🇳 · Qing Wang🇨🇳

    We propose a new method to calculate perturbatively the isospectral Hermitian theory for the $\mathcal{P}\mathcal{T}$-symmetric $i{\varphi }^3$ quantum field theory in $d$ dimensions, whose result is local. The result of the new method in $1$ dimension reproduces our previous result in the $i{x}^3$ quantum mechanics, and the new method can be seen as a generalization of our previous method to quantum field theory. We also find the isospectral local Hermitian theory has the same form in all dimensions and differs in coefficients only, and our previous results in quantum mechanics can be used directly to determine the form of the isospectral local Hermitian quantum field theory.

    ↳ hep-thhep-phPRD(2025)·5 citations
44. 44*

    Probing Decaying Dark Matter Using the Post-EoR HI 21-cm signal

    Mohit Yadav🇮🇳 · Tapomoy Guha Sarkar🇮🇳

    We propose the HI 21-cm power spectrum from the post-reionization epoch as a probe of a cosmological model with decaying dark matter particles. The unstable particles are assumed to undergo a 2-body decay into a massless and massive daughter. We assume that a fraction $f$ of the total dark matter budget to be unstable and quantify the decay using the life time ${\Gamma }^{-1}$ and the relative mass splitting $ϵ$ between the parent and the massive daughter. The redshift space anisotropic power spectrum of the post-reionization 21-cm signal brightness temperature, as a tracer of the dark matter clustering, imprints the decaying dark matter model through its effect on background evolution and the suppression of power on small scales. We find that with an idealized futuristic intensity mapping experiment with a SKA1-Mid like radio-array, $ϵ$ and $\Gamma$ can be measured at $3.37\%$ and $6.86\%$ around their fiducial values of $ϵ=0.012$ and $\Gamma =0.008{\mathrm{Gyr}}^{-1}$ respectively. When only the foreground-free window is considered in the $k-$ space, these percentage errors in $ϵ$ and $\Gamma$ degrade to $9.91\%$ and $12.03\%$ respectively.The forecasts under identical assumptions for a second, literature-anchored benchmark ($ϵ=1.14\times 10^{-4}$, $\Gamma =1.04\times 10^{-3}{\mathrm{Gyr}}^{-1}$) yields projected uncertainties of $6.16\%$ on $ϵ$ and $8.29\%$ on $\Gamma$ while, restricting to the foreground-free window increases these to $18.77\%$ and $14.22\%$, respectively.

    ↳ astro-ph.COgr-qchep-phEPJC(2025)·4 citations
45. 45*

    Dynamics of Hot QCD Matter 2024 -- Bulk Properties

    Prabhakar Palni · Amal Sarkar · Santosh K. Das · Anuraag Rathore · Syed Shoaib · Arvind Khuntia · Amaresh Jaiswal · Victor Roy · Ankit Kumar Panda · Partha Bagchi · Hiranmaya Mishra · Deeptak Biswas and 35 other authors

    The second Hot QCD Matter 2024 conference at IIT Mandi focused on various ongoing topics in high-energy heavy-ion collisions, encompassing theoretical and experimental perspectives. This proceedings volume includes 19 contributions that collectively explore diverse aspects of the bulk properties of hot QCD matter. The topics encompass the dynamics of electromagnetic fields, transport properties, hadronic matter, spin hydrodynamics, and the role of conserved charges in high-energy environments. These studies significantly enhance our understanding of the complex dynamics of hot QCD matter, the quark-gluon plasma (QGP) formed in high-energy nuclear collisions. Advances in theoretical frameworks, including hydrodynamics, spin dynamics, and fluctuation studies, aim to improve theoretical calculations and refine our knowledge of the thermodynamic properties of strongly interacting matter. Experimental efforts, such as those conducted by the ALICE and STAR collaborations, play a vital role in validating these theoretical predictions and deepening our insight into the QCD phase diagram, collectivity in small systems, and the early-stage behavior of strongly interacting matter. Combining theoretical models with experimental observations offers a comprehensive understanding of the extreme conditions encountered in relativistic heavy-ion and proton-proton collisions.

    ↳ nucl-thhep-exhep-phhep-th
46. 46*

    Interference in Fuzzy Dark Matter Filaments: Idealised Models and Statistics

    Tim Zimmermann🇳🇴 · David J.E. Marsh🇬🇧 · Keir K. Rogers🇬🇧 · Hans A. Winther🇳🇴 · Sijing Shen🇳🇴

    Fuzzy (wave) dark matter (FDM), the dynamical model underlying an ultralight bosonic dark matter species, produces a rich set of non-gravitational signatures that distinguishes it markedly from the phenomenologically related warm (particle) dark matter (WDM) scenario. The emergence of extended interference fringes hosted by cosmic filaments is one such phenomenon reported by cosmological simulations, and a detailed understanding of such may strengthen existing limits on the boson mass but also break the degeneracy with WDM, and provide a unique fingerprint of interference in cosmology. In this paper, we provide initial steps towards this goal. In particular, we show in a bottom-up approach, how the presence of interference in an idealised filament population can lead to a non-suppressive feature in the matter power spectrum -- an observation supported by fully-cosmological FDM simulations. To this end, we build on a theoretically motivated and numerically observed steady-state approximation for filaments and express the equilibrium dynamics of such in an expansion of FDM eigenstates. We optimise the size of the expansion by incorporating classical phase-space information. Ellipsoidal collapse considerations are used to construct a fuzzy filament mass function which, together with the reconstructed FDM wave function, allow us to efficiently compute the one-filament power spectrum. We showcase our non-perturbative interference model for a selection of boson masses and confirm our approach is able to produce the matter power boost observed in fully-cosmological FDM simulations. More precisely, we find an excess in correlation between the spatial scale associated with the FDM ground state and the quantum pressure scale. We speculate about applications of this effect in data analysis.

    ↳ astro-ph.COhep-phAstron.Astrophys.(2025)·11 citations
47. 47*

    Classical worldlines from scattering amplitudes

    Zeno Capatti🇨🇭 · Mao Zeng🇬🇧

    We present a systematic diagrammatic investigation of the classical limit of observables computed from scattering amplitudes in quantum field theory through the Kosower-Maybee-O'Connell (KMOC) formalism, motivated by the study of gravitational waves from black hole binaries. We achieve the manifest cancellation of divergences in the $\hslash \to 0$ limit at the integrand level beyond one loop by employing the Schwinger parametrisation to rewrite both cut and uncut propagators in a worldline-like representation before they are combined. The resulting finite classical integrand takes the same form as the counterpart in the worldline formalisms such as post-Minkowskian effective field theory (PMEFT) and worldline quantum field theory (WQFT), and in fact exactly coincides with the latter in various examples, showing explicitly the equivalence between scattering amplitude and worldline formalisms. The classical causality flow, as expressed by the retarded propagator prescription, appears as an emergent feature. Examples are presented for impulse observables in electrodynamics and a scalar model at two loops, as well as certain subclasses of diagrams to higher orders and all orders.

    ↳ hep-thhep-phPRD(2025)·11 citations
48. 48*

    Quantum-Corrected Holographic Wilson Loop Expectation Values and Super-Yang-Mills Confinement

    Xiao-Long Liu🇨🇳 · Cong-Yuan Yue🇨🇳 · Jun Nian🇨🇳 · Wenni Zheng🇨🇳

    Confinement is a well-known phenomenon in the infrared regime of (supersymmetric) Yang-Mills theory. While both experimental observations and numerical simulations have robustly confirmed its existence, the underlying physical mechanism remains elusive. Unraveling the theoretical origin of confinement continues to be a profound and longstanding challenge in both physics and mathematics. Motivated by recent advances in quantum Jackiw-Teitelboim gravity, we investigate the Wilson loop expectation values in the large-$N$ limit of $\mathcal{N}=4$ super-Yang-Mills theory at finite chemical potential, employing a holographic approach within the background of an extremal AdS${}_5$ Reissner-Nordström black brane. Our results reveal that quantum gravitational fluctuations in the near-horizon region significantly modify the holographic Wilson loop expectation values. These values exhibit an area-law behavior, indicative of a confining quark-antiquark potential. Within this framework, our findings suggest that confinement in the super-Yang-Mills theory arises as a consequence of near-horizon quantum gravity fluctuations in the bulk extremal AdS${}_5$ black brane geometry.

    ↳ hep-thgr-qchep-phmath-ph+29 citations
49. 49*

    A New Census of the Universe's Entropy

    Stefano Profumo🇺🇸 · Liam Colombo-Murphy🇺🇸 · Gabriela Huckabee🇺🇸 · Maya Diaz Svensson🇺🇸 · Stuti Garg🇺🇸 · Ishan Kollipara🇺🇸 · Alison Weber🇩🇪

    The question of what is the total entropy of the universe, how it compares to the maximal entropy of de Sitter space, and how it is distributed across the universe's components, bears considerable importance for a number of reasons. Here, we first update the computation of the entropy associated with various sectors of the observed universe, including in the diffuse cosmic and late-time gamma-ray and neutrino backgrounds, in baryonic matter both in diffuse components, in stars and stellar remnants, and in cosmic rays; we then update, crucially, the estimate of entropy in stellar-mass and super-massive black holes, whose abundance and mass function has come into increasingly sharp definition with recent observations and with the rapidly growing statistics of black-hole-black-hole mergers observed with gravity wave detectors. We also provide a new, corrected estimate of the potential entropy associated with a stochastic gravitational wave background, with dark sector radiations, and with several dark matter models. Finally, we utilize the similarly recently updated constraints on the abundance of hypothetical primordial black holes - black holes, that is, of non-stellar origin - to assess the maximal amount entropy they could store. We find that if supermassive primordial black holes exist, they can dominate the entropy budget of the universe consistently with current constraints on their abundance and mass function, to a level potentially not distant from the posited entropy associated with the cosmic event horizon of de Sitter spacetime. The same conclusion holds for certain dark sector models featuring a large number of dark degrees of freedom.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·6 citations
50. 50*

    New BaBar studies of high-order radiation and the new landscape of data-driven HVP predictions of the muon g-2

    Bogdan Malaescu🇫🇷

    A measurement of additional radiation in $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}\gamma$ and $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}\gamma$ initial-state-radiation events is presented using the full $BaBar$ data sample. For the first time results are presented at next-to- and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. The comparison with the predictions from Phokhara and AfkQed generators reveals discrepancies for the former in the one-photon rates and angular distributions. While this disagreement has a negligible effect on the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}(\gamma )$ cross section measured by $BaBar$, the impact on the KLOE and BESIII measurements is estimated and found to be indicative of significant systematic effects. The findings shed a new light on the longstanding deviation among the muon $g-2$ measurement, the Standard Model prediction using the data-driven dispersive approach for calculation of the hadronic vacuum polarization (HVP), and the comparison with lattice QCD calculations.

    ↳ hep-exhep-phPoS(2025)·1 citation
51. 51*

    Collinear anatomy

    A.V. Belitsky🇺🇸

    We study the collinear factorization of off-shell scattering amplitudes in maximally supersymmetric Yang-Mills (sYM) theory. These are constructed starting from six-dimensional N = (1,1) sYM, taking advantage of an available unconstrained spinor-helicity formalism combined with a unitarity-cut sewing procedure. After generalized dimensional reduction, their collinear behavior is dissected with assistance from the Method of Regions. We then construct off-shell splitting amplitudes directly using the same techniques, establishing equivalence to the amplitude analysis. The calculations are performed at one-loop order.

    ↳ hep-thhep-phJHEP(2025)·7 citations
52. 52*

    The cosmic history of Primordial Black Hole accretion and its uncertainties

    Pratibha Jangra🇪🇸 · Daniele Gaggero🇮🇹 · Bradley J. Kavanagh🇪🇸 · J. M. Diego🇪🇸

    Primordial Black Holes (PBHs) have not been experimentally detected so far, but their existence would provide important insights about the early Universe and serve as one of the possible candidates of dark matter (DM). In this work, we explore the accretion of radiation and matter by PBHs, with relevance for the growth of PBH seeds to form early Supermassive Black Holes; the emission from accreting PBHs; and constraints from gravitational wave observations, among others. We study the growth of PBH masses in the early Universe due to the accretion of radiation, highlighting uncertainties which arise from estimates of the PBH formation time. For baryonic accretion, we review the traditional Bondi-Hoyle-Lyttleton (BHL) and its refined version known as the Park-Ricotti (PR) model, which also includes radiative feedback. We find that in the BHL model, PBHs heavier than $\sim 100{\mathrm{M}}_{\odot }$ can grow in mass by several orders of magnitude by $z\lesssim 10$, though only when surrounded by DM halos and only when the accretion efficiency is large. By contrast, the inclusion of radiation feedback in the PR model can drastically suppress the baryonic accretion rate of PBHs, leading to a negligible change in PBH mass over cosmic time. Furthermore our calculations show that the accretion rate depends sensitively on the modelling of various parameters such as the speed of sound in the baryonic gas and the velocity of PBHs. These findings highlight the uncertainties associated with accretion onto PBHs, and we find that a large increase in the PBH mass due to accretion is by no means guaranteed.

    ↳ astro-ph.COhep-phJCAP(2025)·16 citations
53. 53*

    C-R-T Fractionalization in the First Quantized Hamiltonian Theory

    Yang-Yang Li🇨🇳 · Zheyan Wan🇨🇳 · Juven Wang🇬🇧 · Shing-Tung Yau🇨🇳 · Yi-Zhuang You🇺🇸

    Recent research has revealed that the CRT symmetry for fermions exhibits a fractionalization distinct from the ${\mathbb{Z}}_2^{\mathcal{C}}\times {\mathbb{Z}}_2^{\mathcal{R}}\times {\mathbb{Z}}_2^{\mathcal{T}}$ for scalar bosons. In fact, the CRT symmetry for fermions can be extended by internal symmetries such as fermion parity, thereby forming a group extension of the ${\mathbb{Z}}_2$ direct product. Conventionally, a Majorana fermion is defined by one Dirac fermion with trivial charge conjugation. However, when the spacetime dimension $d+1=5,6,7\mathrm{mod}8$, the real dimension of Majorana fermion (dim${}_{\mathbb{R}}{\chi }_{\mathcal{C}\ell (d,0)}$) aligns with the real dimension of Dirac fermion (dim${}_{\mathbb{R}}{\psi }_{\mathcal{C}\ell (d)}$), rather than being half, which necessitates the introduction of a symplectic Majorana fermion, defined by two Dirac fermions with trivial charge conjugation. To include these two types of Majorana fermions, we embed the theory in $n_{\mathbb{R}}$ and define the Majorana fermion field as a representation of the real Clifford algebra with 8-fold periodicity. Within the Hamiltonian formalism, we identify the 8-fold CRT-internal symmetry groups across general dimensions. Similarly, Dirac fermion field is defined as a representation of the complex Clifford algebra with 2-fold periodicity. Interestingly, we discover that the CRT-internal symmetry groups exhibit an 8-fold periodicity that is distinct from that of the complex Clifford algebra. In certain dimensions where distinct mass terms can span a mass manifold, the CRT-internal symmetries can act non-trivially upon this mass manifold. Employing domain wall reduction method, we are able to elucidate the relationships between symmetries across different dimensions.

    ↳ cond-mat.str-elhep-phhep-thmath-ph+2PRB(2026)·3 citations
54. 54*

    Evidence for the Sombrero Galaxy as an Accelerator of the Highest-Energy Cosmic Rays

    Hao-Ning He🇨🇳 · Eiji Kido🇨🇳 · Kai-Kai Duan🇨🇳 · Yang Yang🇨🇳 · Ryo Higuchi🇯🇵 · Yi-Zhong Fan🇨🇳 · Tao Wang🇨🇳 · Lu-Yao Jiang🇨🇳 · Rong-Lan Li🇨🇳 · Ben-Yang Zhu🇨🇳 · Xiang Li🇨🇳 · Zi-Qing Xia🇨🇳 and 3 other authors

    Ultrahigh-energy cosmic rays (UHECRs) are the highest energy messenger from space, with energies exceeding 1 EeV. Although UHECRs were discovered over 60 years ago, their origin still remains a mystery. Pinpointing sources of UHECRs is crucial for understanding the extreme astrophysical processes that accelerate particles to such extraordinary energies. We searched for UHECR multiplets via analyzing 17 years of data with energies greater than 40 EeV from the Pierre Auger Observatory. A spatial association is found between a multiplet of $25.7_{-7.0}^{+6.2}$ cosmic rays and the Sombrero galaxy with a local (global) significance of $4.5\sigma (3.3\sigma )$. The Sombrero galaxy hosts a supermassive central black hole with a mass of $\sim 1\times 10^9{M}_{\odot }$ and exhibits large-scale radio lobes and jets. Our finding provides critical evidence on active supermassive black holes as the source of the highest-energy cosmic rays.

    ↳ astro-ph.HEastro-ph.GAhep-phhep-th8 citations
55. 55*

    Non-Radial Oscillation Modes in Hybrid Stars with Hyperons and Delta Baryons

    Ishfaq Ahmad Rather🇩🇪 · Kau D. Marquez🇧🇷 · Prashant Thakur🇮🇳 · Odilon Lourenço🇧🇷

    We study the effects of hyperons, delta baryons, and quark matter phase transitions on $f$-mode oscillations in neutron stars. Using the density-dependent relativistic mean-field model (DDME2) for the hadronic phase and the density-dependent quark mass (DDQM) model for the quark phase, we construct hadronic and hybrid equations of state (EoSs) consistent with astrophysical constraints. Including hyperons and delta baryons soften the EoS, reducing maximum mass, while phase transition to the quark matter further softens the EoS, decreasing the speed of sound and hence the maximum mass. We confirm the well-known overestimation of $f$-mode frequencies by the Cowling approximation (by about 10-30\%) compared to full General Relativity calculation, and show that this discrepancy persists across models including hyperons, $\Delta$ baryons, and a phase transition to quark matter. While the discrepancy generally decreases with stellar mass, it increases near the maximum mass in the presence of a phase transition compared to EoSs without this phenomenology. We derive universal relations connecting the frequencies of the $f$-mode to the average density, compactness, and tidal deformability, finding significant deviations due to hyperons and delta baryons. These deviations could provide distinct observational signatures in gravitational wave data, offering new insights into dense matter physics and advancing gravitational wave asteroseismology of neutron star interiors. Empirical relations for mass-scaled and radius-scaled frequencies are also provided, highlighting the importance of GR calculations for accurate modeling.

    ↳ astro-ph.HEhep-phnucl-thPRD(2025)·14 citations
56. 56*

    Fuzzy Axions and Associated Relics

    Elijah Sheridan🇺🇸 · Federico Carta🇬🇧 · Naomi Gendler🇺🇸 · Mudit Jain🇬🇧 · David J. E. Marsh🇬🇧 · Liam McAllister🇺🇸 · Nicole Righi🇬🇧 · Keir K. Rogers🇬🇧 · Andreas Schachner🇺🇸

    We study fuzzy axion dark matter in type IIB string theory, for axions descending from the Ramond-Ramond four-form in compactifications on orientifolds of Calabi-Yau hypersurfaces. Such models can be tested by cosmological measurements if a significant relic abundance of fuzzy dark matter arises, which we argue is most common in models with small numbers of axions. We construct a topologically exhaustive ensemble of more than 350,000 Calabi-Yau compactifications yielding up to seven axions, and in this setting we perform a systematic analysis of misalignment production of fuzzy dark matter. In typical regions of moduli space, the fuzzy axion, the QCD axion, and other axions have comparable decay constants of $f_a\approx 10^{16}$ GeV. We find that overproduction of heavier axions is problematic, except at special loci in moduli space where decay constant hierarchies can occur: without a contrived reheating epoch, it is necessary to fine-tune initial displacements. The resulting dark matter is typically a mix of fuzzy axions and heavier axions, including the QCD axion. Dark photons are typically present as a consequence of the orientifold projection. We examine the signatures of these models by simulating halos with multiple fuzzy axions, and by computing new cosmological constraints on ultralight axions and dark radiation. We also give evidence that cosmic birefringence is possible in this setting. Our findings determine the phenomenological correlates of fuzzy axion dark matter in a corner of the landscape.

    ↳ hep-thastro-ph.COhep-phJHEP(2025)·39 citations
57. 57*

    Calabi-Yau Feynman integrals in gravity: $\epsilon$-factorized form for apparent singularities

    Hjalte Frellesvig🇩🇰 · Roger Morales🇩🇰 · Sebastian Pögel🇨🇭 · Stefan Weinzierl🇩🇪 · Matthias Wilhelm🇩🇰

    We study a recently identified four-loop Feynman integral that contains a three-dimensional Calabi-Yau geometry and contributes to the scattering of black holes in classical gravity at fifth post-Minkowskian and second self-force order (5PM 2SF) in the conservative sector. In contrast to previously studied Calabi-Yau Feynman integrals, the higher-order differential equation that this integral satisfies in dimensional regularization exhibits $\epsilon$-dependent apparent singularities. We introduce an appropriate ansatz which allows us to bring such cases into an $\epsilon$-factorized form. As a proof of principle, we apply it to the integral at hand.

    ↳ hep-thgr-qchep-phJHEP(2025)·34 citations
58. 58*

    Comment on "Sustainability Strategy for the Cool Copper Collider", arXiv:2307.04084

    Christophe Grojean🇩🇪 · Patrick Janot🇨🇭

    The paper entitled "Sustainability Strategy for the Cool Copper Collider" by M. Breidenbach et al. defines a metric to weigh the electricity consumption and the carbon footprint of future Higgs factory concepts. We show that this metric is flawed in many respects and gives an incorrect representation of reality. We also demonstrates that, irrespective of the drawbacks of this particular estimator, the strategy consisting in using a metric as a multiplicative coefficient of the electricity consumption or the carbon footprint of an ensemble of colliders is fragile at best, and valueless when it comes to arguing in favour of or against such or such future Higgs Factory concept.

    ↳ hep-exhep-ph0 citations
59. 59*

    Field Redefinitions Can Be Nonlocal

    Timothy Cohen🇨🇭 · Matthew Forslund🇺🇸 · Andreas Helset🇨🇭

    We revisit the lore establishing the allowed space of field redefinitions and show that there are essentially no restrictions. Our conclusions hold to all orders in perturbation theory and for any dispersion relation. Field redefinitions can be nonlocal, symmetry breaking, or in certain cases have explicit dependence on spacetime. We address field redefinitions that can be resummed into the propagator, which demonstrates how to perform perturbative calculations away from the minimum in field space. Field redefinitions are used to derive higher-order Schwinger-Dyson equations, which imply multiparticle soft theorems. Non-standard field redefinitions are showcased using both relativistic and nonrelativistic examples.

    ↳ hep-thhep-phJHEP(2025)·21 citations
60. 60*

    Gauge-Fermion Cartography: from confinement and chiral symmetry breaking to conformality

    Florian Goertz🇩🇪 · Álvaro Pastor-Gutiérrez🇩🇪 · Jan M. Pawlowski🇩🇪

    We study, for the first time, the interplay between colour-confining and chiral symmetry-breaking dynamics in gauge-fermion systems with a general number of flavours and colours. Specifically, we work out the flavour dependence of the confinement and chiral symmetry breaking scales. We connect the QCD-like regime, in quantitative agreement with lattice data, with the perturbative conformal limit, thereby exploring uncharted region of theory space. This analysis is done within the first-principles functional renormalisation group approach to gauge-fermion systems and is facilitated by a novel approximation scheme introduced here. This novel scheme enables a relatively simple access to the confining dynamics. This allows us to investigate the whole landscape of many-flavour theories and to provide a cartography of their phase structure. In particular, we uncover a novel phase with the locking of confining and chiral dynamics at intermediate flavour numbers. We also explore the close-conformal region that displays a walking behaviour. Finally, we provide a quantitative estimate for the lower boundary of the conformal Caswell-Banks-Zaks window, with a $N_f^{\mathrm{crit}}(N_c=3)=9.60_{-0.53}^{+0.55}$. This work offers a self-consistent framework for charting the landscape of strongly interacting gauge-fermion theories necessary to reliably study strongly coupled extensions of the Standard Model of particle physics.

    ↳ hep-thhep-lathep-phPRD(2025)·20 citations
61. 61*

    Gauge invariance and generalised $\eta$ regularisation

    Antonio Padilla🇬🇧 · Robert G. C. Smith🇬🇧

    We generalise the $\eta$ regularisation scheme in order to develop a framework for systematically studying regularisation of loops in quantum field theory. This allows us to "solve" a set of gauge consistency conditions for families of gauge invariant regularisation schemes. We recover several known examples such as dimensional and denominator regularisations, as well as some more general solutions. We also study anomalies in chiral theories in order to carefully describe how our formalism should be properly implemented.

    ↳ hep-thgr-qchep-phmath-ph+1PRD(2025)·7 citations
62. 62*

    Pauli blocking: probing beyond-mean-field effects in neutrino flavor evolution

    Manuel Goimil-García🇩🇰 · Shashank Shalgar🇩🇰 · Irene Tamborra🇩🇰

    Neutrino quantum kinetics in dense astrophysical environments is investigated relying on the mean-field approximation. In this paper, we heuristically explore whether beyond-mean-field effects due to neutrino degeneracy could hinder flavor instabilities that are otherwise foreseen. Our results show that these corrections shift the stability regions for a suite of (anti)neutrino ensembles: the flavor conversion of previously unstable distributions can be damped, but angular distributions that are stable in the mean-field case can also become unstable. Our work should serve as a motivation to further investigate the limitations of the mean-field treatment.

    ↳ astro-ph.HEhep-phPRD(2025)·8 citations
63. 63*

    Higher-order dissipative anisotropic magnetohydrodynamics from the Boltzmann-Vlasov equation

    Etele Molnár🇵🇱 · Dirk H. Rischke🇩🇪

    We apply the method of moments to the relativistic Boltzmann-Vlasov equation and derive the equations of motion for the irreducible moments of arbitrary tensor-rank of the invariant single-particle distribution function. We study two cases, in the first of which the moments are taken to be irreducible with respect to the little group associated with the time-like fluid four-velocity, while in the second case they are assumed to be also irreducible with respect to a space-like four-vector orthogonal to the fluid four-velocity, which breaks the spatial isotropy to a rotational symmetry in the plane transverse to this vector. A systematic truncation and closure of the general moment equations leads, in the first case, to a theory of relativistic higher-order dissipative resistive magnetohydrodynamics. In the second case, we obtain a novel theory of dissipative resistive anisotropic magnetohydrodynamics, where the momentum anisotropy is in principle independent from that introduced by the external magnetic field.

    ↳ physics.plasm-phhep-phnucl-thPRD(2025)·4 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.