Thu·Oct 10, 2024Thursday·October 10, 2024

1. 01*

   Relations Between Anomalous Dimensions in the Regge Limit

   Ira Z. Rothstein🇺🇸 · Michael Saavedra🇺🇸

   We extend the recent formalism developed for computing rapidity anomalous dimension of form factors using unitarity to the problem of high-energy near forward scattering. By combining the factorization of $2\to 2$ scattering in the effective field theory (EFT) for Glauber operators with definite signature amplitudes, we derive an expression that relates anomalous dimensions (including Regge trajectories) to cut amplitudes, leading to significant computational simplifications. We demonstrate this explicitly by computing the one and two-loop Regge trajectories. Our formalism can also be used to bootstrap anomalous dimensions of operators not related by symmetries. As an example, we show that the full anomalous dimensions (including both the Regge pole and cut pieces) of the two Glauber operator anti-symmetric octet operator, can be determined from the anomalous dimension of the single Glauber exchange operator. Many other such relations exist between other color channels at each order in $\alpha$.

   hep-phhep-thnucl-thJHEP(2025)·8 citations
2. 02*

   Probing a scalar singlet-triplet extension of the Standard Model via VBF at the Muon Collider

   Priyotosh Bandyopadhyay🇮🇳 · Snehashis Parashar🇮🇳

   In this article, we investigate the $Y=0$ $SU(2)$ scalar triplet and $Z_2$-odd scalar singlet extension of the Standard Model (SM). Here, the triplet charged Higgs boson decays to $Z{W}^{\pm }$, breaking the custodial symmetry at the tree-level, proportional to the triplet vev, while the singlet provides the dark matter (DM) relic. The triplet neutral Higgs ($T^0$) can decay fully invisibly owing to the triplet-singlet portal coupling ${\lambda }_{st}$. The other SM Higgs portal couplings ${\lambda }_{ht},{\lambda }_{hs}$ are constrained by the Higgs to di-photon observations, and the dark matter relic and direct searches as well as invisible Higgs decay bounds, respectively. For a cleaner signature, we indulge in a futuristic multi-TeV muon collider (MuC) to probe both the triplet scalars ($T^{\pm },T^0$) via vector boson fusion with Forward muon tagging, at the centre-of-mass energies of 3 TeV and 10 TeV. The analysis is comprised of a traditional cut-based approach and a BDT classifier, where the latter is more effective for lower energies. With large missing energy contributions to the final states from combinations of DM mass and ${\lambda }_{st}$, The 3 TeV MuC is projected to probe triplet scalar masses of 450 GeV with the BDT classifier. The 10 TeV MuC can pinpoint the custodial symmetry breaking $T^{\pm }\to Z{W}^{\pm }\to 3$-lepton decay up to 800 GeV of triplet scalar mass from cut-based analysis, with ${\lambda }_{st}$ as low as 1.5 being adequate.

   hep-phPRD(2024)·15 citations
3. 03*

   Describing Hadronization via Histories and Observables for Monte-Carlo Event Reweighting

   Christian Bierlich🇸🇪 · Phil Ilten🇺🇸 · Tony Menzo🇺🇸 · Stephen Mrenna🇺🇸 · Manuel Szewc🇺🇸 · Michael K. Wilkinson🇺🇸 · Ahmed Youssef🇺🇸 · Jure Zupan🇺🇸

   We introduce a novel method for extracting a fragmentation model directly from experimental data without requiring an explicit parametric form, called Histories and Observables for Monte-Carlo Event Reweighting (HOMER), consisting of three steps: the training of a classifier between simulation and data, the inference of single fragmentation weights, and the calculation of the weight for the full hadronization chain. We illustrate the use of HOMER on a simplified hadronization problem, a $q\bar{q}$ string fragmenting into pions, and extract a modified Lund string fragmentation function $f(z)$. We then demonstrate the use of HOMER on three types of experimental data: (i) binned distributions of high level observables, (ii) unbinned event-by-event distributions of these observables, and (iii) full particle cloud information. After demonstrating that $f(z)$ can be extracted from data (the inverse of hadronization), we also show that, at least in this limited setup, the fidelity of the extracted $f(z)$ suffers only limited loss when moving from (i) to (ii) to (iii). Public code is available at https://gitlab.com/uchep/mlhad.

   hep-phhep-exSciPost Phys.(2025)·20 citations
4. 04*

   Recent developments in HQET

   Gil Paz🇺🇸

   In this talk we review recent perturbative and non-perturbative developments in Heavy Quark Effective Theory (HQET).

   hep-phEPJ Web Conf.(2024)·0 citations
5. 05*

   Principle and prospect of Bose-Einstein correlation study at BESIII

   Hai-Ming Hu🇨🇳 · Guang-Shun Huang🇨🇳

   One method for determining the characteristic parameters of a hadron production source is to measure the Bose-Einstein correlation functions. In this study, we present fundamental concepts and formulas related to the Bose-Einstein correlations, focusing on the measurement principles and the Lund model from an experimental perspective. We perform Monte Carlo simulations using the Lund model generator in the 2-3 GeV energy range. Through these feasibility studies, we identify key features of the Bose-Einstein correlations that offer valuable insights for experimental measurements. Utilizing data samples collected at BESIII, we perform measurements of the Bose-Einstein correlation functions, with an expected experimental precision of a few percent for the hadron source radius and incoherence parameter.

   hep-phCPC(2024)·0 citations
6. 06*

   Semileptonic $s\to u$ decays of singly heavy baryons

   Yi-Peng Xing🇨🇳 · Xiao-Qian Jiang🇨🇳 · Zhen-Xing Zhao🇨🇳

   $s\to u$ weak decays of heavy flavor hadrons play a unique role in the field of heavy flavor physics. In this work, we investigate semileptonic $s\to u$ decays of singly heavy baryons in the light-front approach under the three-quark picture. Firstly, we provide all the form factors using this quark model, especially for $f_3$ and $g_3$, which are usually considered non-extractable in recent literature. We also discuss the heavy quark limit for the form factors, and some of our results differ from those in the literature. We find that, when considering the heavy quark limit, the $m_s$ correction may not be negligible. Secondly, we apply the obtained form factors to predict some observables in semileptonic decays. It is worth noting that, due to the extremely small phase space, lepton flavor universality (LFU) is sensitive to the masses of leptons, and precise measurement of LFU is expected to be an important tool for testing the standard model.

   hep-phEPJC(2026)·2 citations
7. 07*

   Coalescence formation of muonic atoms at RHIC

   Xiaofeng Wang🇨🇳 · Frank Geurts🇺🇸 · Zebo Tang🇨🇳 · Kefeng Xin🇺🇸 · Zhangbu Xu🇺🇸 · Yifei Zhang🇨🇳 · Long Zhou🇨🇳

   The discovery of exotic mounic atoms, including antimatter hydrogen muonic atoms and kaon mounic atoms, constitutes a milestone in our ability to make and study new forms of matter. Relativistic heavy-ion collisions provide the only likely condition for production and detection of these exotic atoms. Taking a Coulomb correlations into account from the time of the fireball freeze-out until the formation of a stable atom has dramatic consequence on the expected yields of these atoms. When the coalescence model with the assumption of quantum wave function localization is applied to the formation of muonic atoms, we find that the atom yields are about two orders of magnitude higher than previously predicted.

   hep-phPLB(2025)·2 citations
8. 08*

   A try for dark energy in quantum field theory: The vacuum energy of neutrino field

   Lian-Bao Jia🇨🇳

   The quartic-divergent vacuum energy poses an ultraviolet (UV) challenge (the cosmological constant problem) in probing the nature of dark energy. Here we try to evaluate the contribution of the vacuum energy to dark energy in the UV-free scheme. The result indicates that it is not a problem of a field in the UV region but a question of the contributions of heavy fields being suppressed. Then, we explore an effective description via scale decoupling. The parameter spaces suggest that the vacuum energy of active neutrino fields can naturally meet the observation of dark energy density, and a neutrino with a typical mass $\sim$ 10 meV $(10^{-3}$ eV) is expected. The normal ordering neutrinos are preferred by naturalness, and the neutrino mass window set by dark energy is 6.3 meV $\lesssim m_1\lesssim$ 16.3 meV, 10.7 meV $\lesssim m_2\lesssim$ 18.4 meV, 50.5 meV $\lesssim m_3\lesssim$ 52.7 meV.

   hep-phastro-ph.COgr-qc1 citation
9. 09*

   Single isolated photon production in the NLO${}^{\star }$ approximation of the Parton Reggeization Approach

   Alexey Chernyshev🇷🇺 · Vladimir Saleev🇷🇺

   The hadroproduction of single isolated photon at high energies is studied within the framework of the NLO${}^{\star }$ approximation of the Parton Reggeization Approach based on the modified Multi-Regge limit of the hard scattering QCD amplitudes. The contribution from the LO subprocess $Q\bar{Q}\to \gamma$ and the NLO tree-level corrections $QR\to \gamma q$ and $Q\bar{Q}\to \gamma g$ are considered. To avoid specific double counting in rapidity between tree-level corrections to the hard scattering coefficient and unintegrated PDFs, a corresponding subtraction scheme is proposed. We demonstrated self-consistency of the Parton Reggeization Approach using the subtraction scheme. The results of calculations are compared with data from various Collaborations in the wide energy range $\sqrt{S}=24\mathrm{GeV}-13\mathrm{TeV}$. We obtained a quite satisfactory agreement with data up to $p_T^{\gamma }/\sqrt{S}\simeq 0.2-0.3$. Predictions for the future SPD NICA experiment were discussed.

   hep-phPRD(2024)·3 citations
10. 10*

    Centrality Manipulation in Exclusive Photoproduction at the Electron-Ion Collider

    Xin Wu🇨🇳 · Xinbai Li🇨🇳 · Zebo Tang🇨🇳 · Kaiyang Wang🇨🇳 · Wangmei Zha🇨🇳

    In the context of future electron-ion collision experiments, particularly the Electron-Ion Collider (EIC) and the Electron-Ion Collider in China (EicC), investigating exclusive photoproduction processes is of paramount importance. These processes offer a unique opportunity to probe the gluon structure of nuclei across a broad range of Bjorken-$x$, facilitating measurements of nuclear shadowing and searches for gluon saturation and/or the color glass condensate. This paper explores the potential of utilizing neutron tagging from Coulomb excitation of nuclei to effectively determine centrality for exclusive photoproduction in electron-ion collisions. By developing the equivalent photon approximation for fast-moving electrons, this work incorporates a coordinate-space-dependent photon flux distribution, elucidating the relationship between the photon transverse momentum distribution and collision impact parameter. Leveraging spatial information from the photon flux, the differential cross section for Coulomb excitation of nuclei is derived. Our calculations demonstrate that neutron tagging can significantly alter impact parameter distributions, thereby providing a robust method for centrality manipulation in electron-ion collisions. This study contributes essential baseline and strategies for exploring the impact parameter dependence of exclusive photoproduction, offering novel insights for experimental design and data analysis. Ultimately, it provides additional information to better visualize the gluon distribution within the nucleus.

    hep-ph3 citations
11. 11*

    Inclusive rare ${\Lambda }_b$ decays to photon

    Francesco Loparco🇮🇹

    Inclusive $H_b\to X_s\gamma$ decays, with $H_b$ a beauty baryon, are treated exploiting an expansion up to the third order in the inverse of the $b$ quark mass $m_b$ and to LO in ${\alpha }_s$, keeping the dependence on the hadron spin. Double distribution $\frac{d^2\Gamma }{dyd\cos {\theta }_P}$ is computed for polarized baryons, with $y=2E_{\gamma }/m_b$, $E_{\gamma }$ the photon energy and ${\theta }_P$ the angle between the baryon spin vector and the photon momentum in the $H_b$ rest-frame. Modifications to the photon polarization asymmetry can probe effects of physics beyond the Standard Model. A systematic method to treat the singular terms in the photon energy spectrum obtained by the OPE is proposed.

    hep-phEPJ Web Conf.(2024)·0 citations
12. 12*

    Transition rate and gravitational wave spectrum from first-order QCD phase transitions

    Jingdong Shao🇨🇳 · Hong Mao🇨🇳 · Mei Huang🇨🇳

    We investigate the gravitational wave spectrum induced by first-order QCD phase transitions including the deconfinement phase transition in the pure gluon system and Friedberg-Lee model, and chiral phase transition in the quark-meson model and Polyakov quark-meson model. The gravitational wave power spectra are sensitive to the phase transition rate $\beta /H$. All QCD models predict a rather large phase transition rate in the order of $\beta /H\sim 10^4$ at high temperature region, and the produced gravitational waves lie in the peak frequency region of $10^{-4}-0.01\mathrm{Hz}$, corresponding to an energy spectrum in the range of $10^{-8}-10^{-7}$, which can be detected by LISA and Taiji. If a high baryon density is generated through Affleck-Dine baryogenesis or other mechanisms, the baryon chemical potential significantly reduces the phase transition rate, potentially dropping it to the order of $\beta /H\sim 10^1$, leading to the production of nanohertz gravitational waves. Furthermore, a critical quark chemical potential exists with a zero phase transition rate $\beta /H=0$, indicating that the false vacuum will not decay, thus supporting the formation of primordial quark nuggets in the early universe.

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

    One-loop analytical expressions for $\gamma \gamma \to {\varphi }_i{\varphi }_j$ in Higgs Extensions of the Standard Models and its applications

    Khiem Hong Phan (DTU)🇩🇰 · Dzung Tri Tran (DTU)🇩🇰 · Thanh Huy Nguyen (HCMUS)🇻🇳

    General one-loop formulas for loop-induced processes $\gamma \gamma \to {\varphi }_i{\varphi }_j$ with ${\varphi }_i{\varphi }_j=hh,hH,HH$ are presented in the paper. Analytic expressions evaluated in this work are valid for a class of Higgs Extensions of the Standard Models, e.g. Inert Doublet Higgs Models, Two Higgs Doublet Models, Zee-Babu Models as well as Triplet Higgs Models, etc. Analytic expressions for one-loop form factors are written in terms of the basic scalar one-loop two-, three- and four-point functions following the output format of both the packages~{\tt LoopTools} and {\tt Collier}. Physical results can be hence evaluated numerically by using one of the mentioned packages. Analytic results are tested by several checks such as the ultraviolet finiteness, infrared finiteness of the one-loop amplitudes. Furthermore, the amplitudes also obey the ward identity due to the on-shell initial photons. This identity is also verified numerically in this works. In the applications, we present the phenomenological results for Zee-Babu model as a typical example in this report. Production cross-section for the processes $\gamma \gamma \to hh$ are scanned over the parameter space of the Zee-Babu Models.

    hep-phCPC(2025)·2 citations
14. 14*

    A New-Old Approach to Composite Scalars with Chiral Fermion Constituents

    Christopher T. Hill🇺🇸

    We develop a dynamical, Lorentz invariant theory of composite scalars in configuration space consisting of chiral fermions, interacting by the perturbative exchange of a massive "gluon" of coupling $g_0$ and mass $M_0^2$ (the coloron model). The formalism is inspired by, but goes beyond, old ideas of Yukawa and the Nambu-Jona-Lasinio (NJL) model. It yields a non-pointlike internal wave-function of the bound state, $\varphi (r)$, which satisfies a Schrödinger-Klein-Gordon (SKG) equation with eigenvalue ${\mu }^2$. For super-critical coupling, $g_0>g_{0c}$, we have ${\mu }^2<0$ leading to spontaneous symmetry breaking. The binding of chiral fermions is semiclassical, and not loop-level as in NJL. The mass scale is determined by the interaction as in NJL. We mainly focus on the short-distance, large $M_0^2$ limit, yielding an NJL pointlike interaction, but the bound state internal wave-function, $\varphi (r)$, remains spatially extended and dilutes $\varphi (0)$. This leads to power-law suppression of the induced Yukawa and quartic couplings and requires radically less fine-tuning of a hierarchy than does the NJL model. We include a discussion of loop corrections of the theory. A realistic top--condensation model appears possible.

    hep-phhep-exhep-thnucl-thNPB(2025)·3 citations
15. 15*

    A Brief Guide to Exotic Hadrons

    Nils Hüsken🇩🇪 · Elisabetta Spadaro Norella🇮🇹 · Ivan Polyakov🇨🇭

    Exotic hadrons are a new class of hadronic states whose properties do not allow them to be classified as conventional quark-antiquark mesons or three quark baryons. Finding new and understanding established exotic states is the most important topic in today's hadron spectroscopy and a promising avenue to advance our knowledge on Quantum Chromodynamics in the non-perturbative regime. While several high-quality reviews on the topic exist, they are all at an advanced level. The present article aims to address new-comers to the field with a simple introduction to exotic hadrons with an emphasis on the experimental studies.

    hep-phhep-exMod.Phys.Lett.A(2025)·30 citations
16. 16*

    Machine learning tagged boosted dark photon: A signature of fermionic portal matter at the LHC

    Shivam Verma🇮🇳 · Sanjoy Biswas🇮🇳 · Tanumoy Mandal🇮🇳 · Subhadip Mitra🇮🇳

    We use a Hybrid Deep Neural Network (HDNN) to identify a boosted dark photon jet as a signature of a heavy vector-like fermionic portal matter (PM) connecting the visible and the dark sectors. In this work, the fermionic PM, which mixes only with the Standard Model (SM) third-generation up-type quark, predominantly decays into a top quark and a dark photon pair. The dark photon then promptly decays to a pair of standard model fermions via the gauge kinetic mixing. We have analyzed two different final states, namely, (i) exactly one tagged dark photon and exactly one tagged top quark jet, and (ii) at least two tagged dark photons and at least one tagged top quark jet at the 13 and 14 TeV LHC center of mass energies. Both these final states receive significant contributions from the pair and single production processes of the top partner. The rich event topology of the signal processes, i.e., the presence of a boosted dark photon and top quark jet pair, along with the fact that the invariant mass of the system corresponds to the mass of the top partner, help us to significantly suppress potential SM backgrounds. We have shown that one can set a $2\sigma$ exclusion limit of $\sim 2.3$ TeV on the top partner mass with $\sin {\theta }_L=0.1$ and assuming $100\%$ branching ratio of the top partner in the final state with exactly one tagged dark photon and exactly one tagged top quark jet at the 14 TeV LHC center of mass energy assuming 300 fb${}^{-1}$ of integrated luminosity.

    hep-phhep-exPRD(2025)·2 citations
17. 17*

    Exclusive rare semileptonic decays of $B$ and $B_c$ mesons in the relativistic independent quark model

    Kalpalata Dash🇮🇳 · P. C. Dash🇮🇳 · R. N. Panda🇮🇳 · Susmita Kar🇮🇳 · N. Barik🇮🇳

    We investigate the exclusive rare semileptonic decays: $B(B_c)\to K(D_{(s)})l\bar{l}/\Sigma {\nu }_l\overline{{\nu }_l}$ ($l=\mu ,\tau$) in the framework of relativistic independent quark (RIQ) model based on an average flavor independent confining potential in equally mixed scalar-vector harmonic form. The invariant weak form factors, parametrising the matrix elements between participating meson states are calculated in the parent meson rest frame. The momentum transfer dependence of the form factors is reliably determined in the whole accessible kinematical range: $q_{min}^2\le 0\le q_{max}^2$. Our predicted branching fractions for $B\to K{\mu }^{+}{\mu }^{-}/{\tau }^{+}{\tau }^{-}(\Sigma {\nu }_l\overline{{\nu }_l})$, $B_c\to D(D_s){\mu }^{+}{\mu }^{-}$, $B_c\to D(D_s){\tau }^{+}{\tau }^{-}$ and $B_c\to D(D_s)\Sigma {\nu }_l\overline{{\nu }_l}$, obtained in order of $10^{-7}(10^{-6})$, $10^{-9}(10^{-7})$, $10^{-9}(10^{-8})$ and $10^{-8}(10^{-7})$, respectively are in reasonable agreement with other Standard Model predictions and Lattice QCD results. The averaged values of the lepton polarization asymmetries for decay modes are obtained as $⟨P_L(B\to K{\mu }^{+}{\mu }^{-})⟩$=-0.97, $⟨P_L(B_c\to D_{(s)}{\mu }^{+}{\mu }^{-})⟩$=-0.972, $⟨P_L(B\to K{\tau }^{+}{\tau }^{-})⟩$=-0.224, $⟨P_L(B_c\to D{\tau }^{+}{\tau }^{-})⟩$=-0.275 and $⟨P_L(B_c\to D_s{\tau }^{+}{\tau }^{-})⟩$=-0.194.

    hep-phnucl-thPRD(2024)·1 citation
18. 18*

    Updated Determination of Ellis-Jaffe Sum Rules up to ${\mathrm{N}}^3\mathrm{LO}$ QCD corrections

    Hua Zhou (Southwest University of Science and Technology)🇨🇳 · Qing Yu (Southwest University of Science and Technology)🇨🇳 · Xing-Gang Wu (Chongqing University)🇨🇳

    In this paper, we explore the properties of the Ellis-Jaffe Sum Rule (EJSR) by employing the Principle of Maximum Conformality (PMC) approach to address its perturbative part up to next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$) QCD contributions. By applying the PMC, we achieve a precise perturbative QCD prediction for the EJSR, free from conventional ambiguities associated with the renormalization scale choices. Considering the presence of the ${\alpha }_s$ Landau pole near the asymptotic scale, we incorporate the low-energy ${\alpha }_s$ model based on analytic perturbation theory (APT) to refine the EJSR behavior in the infrared region. By combining the PMC approach with the low-energy APT model, the agreement between theoretical calculations and experimental measurements of EJSR is significantly improved, as evidenced by the reduced discrepancy from ${\chi }^2/d.o.f{|}_{Conv.}=1.86$ to ${\chi }^2/d.o.f{|}_{\mathrm{PMC}}=1.19$, thereby validating the effectiveness of our approach.

    hep-phPLB(2025)·0 citations
19. 19*

    Relaxing Limits from Big Bang Nucleosynthesis on Heavy Neutral Leptons with Axion-like Particles

    Frank F. Deppisch🇬🇧 · Tomás E. Gonzalo🇩🇪 · Chayan Majumdar🇬🇧 · Zhong Zhang🇬🇧

    Heavy neutral leptons (HNLs) are constrained by requirements of Big Bang Nucleosynthesis (BBN) as their decays significantly impact the formation of the primordial elements. We propose here a model where the primary decay channel for the HNLs is to an axion-like particle (ALP) and a neutrino. Consequently, HNLs can decay earlier and evade the BBN bound for lower masses, provided the ALPs themselves decay considerably later. Further cosmological and astrophysical constraints limit severely the range of validity of the ALP properties. We find that a new parameter region opens up for HNLs with masses between 1 MeV and 1 GeV, and active-sterile neutrino mixing strengths between $10^{-9}$ and $10^{-6}$ that is consistent with constraints and can be probed in future searches. In such a scenario, current bounds as well as sensitivities of future direct HNL searches such as at NA62 and DUNE will be affected.

    hep-phastro-ph.COJCAP(2025)·13 citations
20. 20*

    Higgs-muon interactions at a multi-TeV muon collider

    Yang Ma🇮🇹 · Eugenia Celada🇬🇧 · Tao Han🇺🇸 · Wolfgang Kilian🇩🇪 · Nils Kreher🇩🇪 · Fabio Maltoni🇧🇪 · Davide Pagani🇮🇹 · Jürgen Reuter🇩🇪 · Tobias Striegl🇩🇪 · Keping Xie🇺🇸

    We establish a simple yet general parameterization of Higgs-muon interactions within the effective field theory frameworks, including both the Higgs Effective Field Theory (HEFT) and the Standard Model Effective Field Theory (SMEFT). We investigate the potential of a muon collider, operating at center-of-mass energies of 3 and 10 TeV, to probe Higgs-muon interactions. All possible processes involving the direct production of multiple electroweak bosons ($W$, $Z$, and $H$) with up to five final-state particles are considered. Our findings indicate that a muon collider can achieve greater sensitivity than the high-luminosity LHC, especially considering the independence of the Higgs decay branching fraction to muons. Notably, a 10 TeV muon collider offers exceptional sensitivity to muon-Higgs interactions, surpassing the 3 TeV option. In particular, searches based on multi-Higgs production prove highly effective for probing these couplings.

    hep-phhep-exhep-thPoS(2024)·3 citations
21. 21*

    KKMCee: Multi-photon MC for lepton and quark pair production at lepton colliders

    Scott A. Yost🇺🇸 · Stanisław Jadach🇵🇱 · B.F.L. Ward🇺🇸 · Zbigniew Wąs🇵🇱 · Andrzej Siódmok🇵🇱

    We present an overview of the Monte Carlo event generator KKMCee for lepton and quark pair production in the high energy electron-positron annihilation process. We note that it is still the most sophisticated event generator for such processes. Its entire source code has been rewritten in C++. We have verified that the new version, KKMCee 5.00, reproduces the benchmarks of the older code in FORTRAN 77. We discuss a number of improvements in the MC algorithm and its interfaces.

    hep-phPoS(2025)·1 citation
22. 22*

    Advancing Tools for Simulation-Based Inference

    Henning Bahl🇩🇪 · Victor Bresó🇩🇪 · Giovanni De Crescenzo🇩🇪 · Tilman Plehn🇩🇪

    We study the benefit of modern simulation-based inference to constrain particle interactions at the LHC. We explore ways to incorporate known physics structures into likelihood estimation, specifically morphing-aware estimation and derivative learning. Technically, we introduce a new and more efficient smearing algorithm, illustrate how uncertainties can be approximated through repulsive ensembles, and show how equivariant networks can improve likelihood estimation. After illustrating these aspects for a toy model, we target di-boson production at the LHC and find that our improvements significantly increase numerical control and stability.

    hep-phhep-exSciPost Phys.Core(2025)·19 citations
23. 23*

    Two-Loop Running in the Bosonic SMEFT Using Functional Methods

    Lukas Born🇨🇭 · Javier Fuentes-Martín🇪🇸 · Sandra Kvedaraitė🇪🇸 · Anders Eller Thomsen🇨🇭

    The next goalpost in precision calculations for physics beyond the Standard Model is determining the two-loop renormalization group (RG) equations in the Standard Model Effective Field Theory (SMEFT). We progress towards this goal by determining the RG equations for a simplified version of the SMEFT without any fermion fields. Our calculation relies on functional methods that are newly developed for multi-loop computations and adapted for the determination of RG equations here.

    hep-phhep-thJHEP(2025)·45 citations
24. 24*

    Hybrid SO(10) Axion Model Without Quality Problem

    K.S. Babu🇺🇸 · Bhaskar Dutta🇺🇸 · Rabindra N. Mohapatra🇺🇸

    Invisible axion models that solve the strong CP problem via the Peccei-Quinn (PQ) mechanism typically have a quality problem that arises from quantum gravity effects which violate all global symmetries. These models therefore require extreme fine-tuning of parameters for consistency. We present a new solution to the quality problem in a unified $SO(10)\times U(1{)}_a$ gauge model, where $U(1{)}_a$ is an anomaly free axial gauge symmetry. PQ symmetry emerges as an accidental symmetry in this setup, which admits a PQ breaking scale as large as $4\times 10^{11}$ GeV, allowing for the axion to be the cosmological dark matter. We call this a hybrid axion model due to its unique feature that it interpolates between the popular KSVZ and DFSZ axion models. Its predictions for the experimentally measurable axion couplings to the nucleon and electron are distinct from those of the usual models, a feature that can be used to test it. Furthermore, the model has no domain wall problem and it provides a realistic and predictive framework for fermion masses and mixings.

    hep-phhep-thPRL(2025)·12 citations
25. 25*

    Constraints on Long-Ranged Interactions Between Dark Matter and the Standard Model

    Zachary Bogorad🇺🇸 · Peter Graham🇺🇸 · Harikrishnan Ramani🇺🇸

    Dark matter's existence is known thanks to its gravitational interaction with Standard Model particles, but it remains unknown whether this is the only force present between them. While many searches for such new interactions with dark matter focus on short-range, contact-like interactions, it is also possible that there exist weak, long-ranged forces between dark matter and the Standard Model. In this work, we present two types of constraints on such new interactions. First, we consider constraints arising from the fact that such a force would also induce long range interactions between Standard Model particles themselves, as well as between dark matter particles themselves. Combining the constraints on these individual forces generally sets the strongest constraints available on new Standard Model-dark matter interactions. Second, we consider the possibility of constraining new long-ranged interactions between dark matter and the Standard Model using the effects of dynamical friction in ultrafaint dwarf galaxies, especially Segue I. Such new interactions would accelerate the transfer of kinetic energy from stars to their surrounding dark matter, slowly reducing their orbits; the present-day stellar half-light radius of Segue I therefore allows us to exclude new forces which would have reduced stars' orbital radii below this scale by now.

    hep-phastro-ph.COastro-ph.GAJCAP(2025)·8 citations
26. 26*

    Searching for ultra-light dark matter through frequency modulation of gravitational waves

    Diego Blas🇪🇸 · Silvia Gasparotto🇪🇸 · Rodrigo Vicente🇳🇱

    Ultra-light bosons, naturally appearing in well-motivated extensions to the Standard Model, can constitute all the dark matter. Models with particle mass close to the smallest phenomenologically allowed exhibit coherent field configurations at (sub)galactic scales, oscillating at a frequency corresponding to the fundamental mass of the dark matter particle. The gravitational field of these structures inherits the dark matter field's coherent oscillations, leaving an imprint on gravitational (and electromagnetic) waves sourced close to (or in) such overdensities. This happens via a heterodyning frequency modulation, which can later be decoded in a gravitational-wave detector. An analogous effect occurs in models with universal (conformal) couplings of ultra-light bosons with ordinary matter, generated by the direct interaction with the oscillating field. In this work, we explore this phenomenon in detail and assess the capability of near-future interferometers to probe ultra-light dark matter and its potential conformal couplings to matter. Using astrophysical population models, together with results from cosmological simulations, we find that the observation of gravitational waves from spinning neutron stars at the Galactic Centre with the Einstein Telescope/Cosmic Explorer would be particularly effective in constraining ultra-light dark matter.

    hep-phgr-qcPRD(2025)·28 citations
27. 27*

    BBN Constraint on Heavy Neutrino Production and Decay

    Yu-Ming Chen🇨🇦 · Yue Zhang🇨🇦

    We explore the big-bang nucleosynthesis (BBN) constraint on heavy neutrino that is a mixture of gauge singlet fermion and active neutrinos in the Standard Model. We work in the minimal model with only two parameters, the heavy neutrino mass $m_4$ and the mixing parameter $|U_{a4}{|}^2$, where $a=e$, $\mu$, or $\tau$ stands for the active neutrino flavor. We show that both the early universe production mechanism and decay products of the heavy neutrino are determined by $m_4$ and $|U_{a4}{|}^2$, with little room for further assumptions. This predictivity allows us to present a portrait of the entire BBN excluded parameter space. Our analysis includes various effects including temporary matter domination, energy injections in the form of charged mesons, photons and light neutrinos. The BBN constraint is complementary to terrestrial search for heavy neutrinos (heavy neutral leptons) behind the origin of neutrino masses and portal to the dark sector.

    hep-phastro-ph.COhep-exPRD(2025)·12 citations
28. 28*

    Outlook for the Theoretical Precision of the Luminosity at Future Lepton Colliders

    B.F.L. Ward (1)🇺🇸 · S. Jadach (2)🇵🇱 · W. Placzek (3)🇵🇱 · M. Skrzypek (2)🇵🇱 · S.A. Yost (4) ((1) Baylor University, Waco, TX, USA, (2) Institute of Nuclear Physics, Krakow, PL, (3) Institute of Applied Computer Science, Jagiellonian University, Krakow, PL, (4) The Citadel, Charleston, SC, USA)🇺🇸

    The LEP precision physics requirements on the theoretical precision tag for the respective luminosity were $0.054\%$ ($0.061\%$) at $M_Z$, where the former (latter) LEP result has (does not have) the pairs correction. For the contemplated FCC-ee, ILC, and CEPC Higgs/EW factories, one needs improvement at $M_Z$ to at least $0.01\%$ for the theoretical precision tag. We discuss the paths one may take to even exceed this latter goal and present an update on the current expectations for both $M_Z$ and proposed higher energy scenarios.

    hep-phPoS(2025)·2 citations
29. 29*

    Collinearly Enhanced YFS MC Approach to Precision High Energy Collider Physics

    B.F.L. Ward (1)🇺🇸 · S. Jadach (2)🇵🇱 · Z. Was (2) ((1) Baylor University, Waco, TX, USA, (2) Institute of Nuclear Physics, Krakow, PL)🇵🇱

    We improve the YFS IR resummation theory so that it includes all of the attendant collinear contributions which exponentiate. The attendant new resummed contributions are shown to agree with known results from the collinear factorization approach. We argue that they improve the corresponding precision tag for a given level of exactness in the respective YFS hard radiation residuals as the latter are realized in the YFS MC approach to precision high-energy collider physics.

    hep-phPoS(2025)·0 citations
30. 30*

    Phenomenology of matching exponentiated photonic radiation to a QED-corrected parton shower in KKMChh

    Scott A. Yost🇺🇸 · B.F.L. Ward🇺🇸 · Zbigniew Wąs🇵🇱

    KKMChh is a precision Monte Carlo program for photonic and electroweak radiative corrections to hadron scattering, implementing the amplitude-level exponentiation originally developed for electron-positron scattering at the quark level, modeling initial and final state QED radiation as well as initial-final interference to all orders in a soft-photon approximation, adding hard photon corrections through second order next-to-leading logarithm. A previous ICHEP talk introduced a matching procedure NISR (negative initial-state radiation) to match the exponentiated photon radiation from the quarks to a QED-corrected parton shower. Here, we describe its effect on forward-backward asymmetry calculations of interest for a precise determination of the electroweak mixing angle.

    hep-phPoS(2025)·1 citation
31. 31*

    Bridging inflation and reheating: chiral gravitational waves from aHz to GHz

    Chengjie Fu🇨🇳 · Chao Chen🇨🇳 · Yi Wang🇨🇳

    In this paper, we investigate chiral gravitational wave (GW) signals generated from inflation to reheating, driven by a parity-violating (PV) term coupled to the inflaton, $\dot{\varphi }{ϵ}^{ijk}{h}_{il}{\partial }_j{h}_k^l$, which naturally arises in PV extensions of teleparallel gravity. During inflation, the PV term reduces the sound horizon for right-handed circularly polarized GWs, and amplifies their power spectra relative to left-handed GWs. At CMB scales, these chiral GWs induce BB as well as non-vanishing EB and TB correlations in CMB, which are potentially detectable by LiteBIRD. During reheating, subhorizon modes undergo tachyonic instability, leading to fully circularly polarized GWs with enhanced amplitudes, which may be probed by future high-frequency GW experiments, such as resonant cavity. The absence of backreaction effect of enhanced chiral GWs imposes constraints on the energy scale of the PV term, the inflationary potential, and the reheating history. Our findings highlight the potential of multi-frequency GW experiments to offer a unique probe of the parity violation and early Universe.

    ↳ astro-ph.COgr-qchep-phPRD(2026)·4 citations
32. 32*

    The Energy Sharing Timescale in an Analytic Framework for Common Envelope Hydrodynamics

    Rosa Wallace Everson · Morgan MacLeod · Enrico Ramirez-Ruiz

    We propose a new predictive theory for the analysis of common envelope (CE) events which incorporates the effects of relevant hydrodynamical processes into a simple analytical framework. We introduce the ejection and dynamical parameters $\xi$ and $\beta$, which define if envelope ejection is energetically or hydrodynamically favorable, respectively, during CE inspiral. When combined, these parameters offer a detailed narrative of how inspiral begins, proceeds, and ends that is consistent with preliminary comparisons to 3D hydrodynamical models. This physically-motivated framework impacts predictions for CE outcomes, especially for systems that have energy excess, and offers promise as a potential alternative for the treatment of CE in binary population synthesis.

    ↳ astro-ph.HEastro-ph.SRhep-phApJL(2025)·4 citations
33. 33*

    Ultralight Black Holes as Sources of High-Energy Particles

    Michael Zantedeschi🇨🇳 · Luca Visinelli🇨🇳

    The \textit{memory burden} effect, the idea that the amount of information stored within a system contributes to its stabilization, is particularly relevant for systems with a large information storage capacity, such as black holes. In these objects, the evaporation process halts, at the latest, once approximately half of the initial mass has been radiated away. As a result, light primordial black holes (PBHs) with mass $m_{\mathrm{PBH}}\lesssim 10^{15}\mathrm{g}$, which are traditionally assumed to have fully evaporated by the present time, may instead survive and constitute viable dark matter candidates. Ongoing mergers of such PBHs would give rise to ``young'' black holes that resume their evaporation, emitting ultrahigh-energy particles potentially detectable by current experiments. The resulting emission spectrum would be thermal across all Standard Model particle species, offering a clear and distinctive signature. We demonstrate that, if the memory burden effect activates after PBHs have lost around half of their initial mass, current measurements of the neutrino flux at Earth place strong constraints on such dark matter candidates for $m_{\mathrm{PBH}}\lesssim 10^9\mathrm{g}$. This suggests that the memory burden must set in at earlier stages of evaporation. Unlike existing bounds, our results depend solely on the mass of the remnant, and not on model-dependent details of the stabilized phase. We also discuss the potential for refining these constraints through observations of gamma rays, cosmic rays, and gravitational waves.

    ↳ astro-ph.HEhep-phhep-thPhys.Dark Univ.(2025)·61 citations
34. 34*

    Constraints on the Sharpness of the Curvature Power Spectrum

    Keisuke Inomata🇺🇸 · Xuheng Luo🇺🇸

    Motivated by the fact that a sharply peaked curvature spectrum is often considered in the literature, we examine theoretical constraints on the sharpness of such a spectrum. In particular, we show that the sharply peaked curvature power spectrum, originating from the enhancement of subhorizon perturbations during inflation, is significantly constrained by energy conservation. While the constraints do not depend on the exact form of inflaton potential, we also study concrete inflaton potentials that realize a sharply peaked curvature spectrum and how theoretical limits are saturated in these cases.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·5 citations
35. 35*

    Simulating realistic self-interacting dark matter models including small and large-angle scattering

    Cenanda Arido🇩🇪 · Moritz S. Fischer🇩🇪 · Mathias Garny🇩🇪

    Dark matter (DM) self-interactions alter the matter distribution on galactic scales and alleviate tensions with observations. A feature of the self-interaction cross section is its angular dependence, influencing offsets between galaxies and DM halos in merging galaxy clusters. While algorithms for modelling mostly forward-dominated or mostly large-angle scatterings exist, incorporating realistic angular dependencies, such as light mediator models, within $N$-body simulations remains challenging. We develop, validate and apply a novel and efficient method, combining existing approaches to describe small- and large-angle scattering regimes within a hybrid scheme. Below a critical angle the effective description via a drag force combined with transverse momentum diffusion is used, while above the angle dependence is sampled explicitly. First, we verify the scheme using a test set-up with known analytical solutions, and check that our results are insensitive to the choice of the critical angle within an expected range. Next, we demonstrate that our scheme speeds up the computations by multiple orders of magnitude for realistic light mediator models. Finally, we apply the method to galaxy cluster mergers and discuss the sensitivity of the offset between galaxies and DM to the angle dependence of the cross section. Our scheme ensures accurate offsets for mediator mass $m_{\varphi }$ and DM mass $m_{\chi }$ within the range $0.1v/c\lesssim m_{\varphi }/m_{\chi }\lesssim v/c$, while for larger (smaller) mass ratios the offsets obtained for isotropic (forward-dominated) self-scattering are approached. Here $v$ is the typical velocity scale. Equivalently, the upper condition can be expressed as $1.1\lesssim {\sigma }_{\mathrm{tot}}/{\sigma }_{\tilde{\mathrm{T}}}\lesssim 10$ for the ratio of the total and momentum transfer cross sections, with the ratio being $1$ ($\infty$) in the isotropic (forward-dominated) limits.

    ↳ astro-ph.COastro-ph.GAhep-phAstron.Astrophys.(2025)·10 citations
36. 36*

    Fundamental constants: from measurement to the universe, a window on gravitation and cosmology

    Jean-Philippe Uzan🇫🇷

    Fundamental constants are a cornerstone of the physical laws. Any constant varying in space and/or time would signal a violation of local position invariance and be associated with a violation of the universality of free fall, and hence of the weak equivalence principle. It will reflect the existence of new degrees of freedom that couple to standard matter. Thus, testing for the stability of fundamental constants is of utmost importance for our understanding of gravity and for characterizing the domain of validity of General Relativity. Besides, it opens an independent window on dark matter and dark energy. As a consequence, thanks to the active development of experiments and of their accuracy, fundamental constants have become a key player in our search for physics beyond the standard model of and beyond General Relativity. This review details the roles of the fundamental constants in the laws of physics and in the construction of the International System of units. Then, the relations between constants, tests of the local position invariance and of the universality of free fall are exposed, as well as the construction of field theories that account for "varying constants". Then, the main experimental and observational constraints are described. It details the basics of each system, its dependence with respect to the primary parameters the variation of which can be constrained from observations, the known systematics effects and the most recent constraints. It also describes how these primary parameters can be related to the fundamental constants and the model-dependencies. Both time and space variation are considered. Given the huge increase of data and constraints, a general scheme to present experimental and observational results and to construct a collaborative data base that will be more efficient for the community and allow for better traceability, is proposed.

    ↳ astro-ph.COgr-qchep-phLiving Rev.Rel.(2025)·59 citations
37. 37*

    Maximal chirality transfer in the photon-graviton conversion in the early universe

    Ashu Kushwaha🇮🇳 · Rajeev Kumar Jain🇮🇳

    While photons and gravitons do not interact significantly, photons can be converted to gravitons in a background magnetic field -- a phenomenon known as the Gertsenshtein effect. In this paper, we investigate whether chiral electromagnetic (EM) waves can be converted to chiral gravitational waves (GW) in the presence of primordial magnetic fields during the radiation-dominated epoch of the early universe. We consider two situations wherein chirality is either present in the propagating EM waves or it exists in the background magnetic field. Our analysis shows that while the conversion probability increases with stronger magnetic fields, it remains insensitive to the chiral nature of the background magnetic field. Consequently, the net chirality parameter is independent of the chirality of the background field in both cases. Finally, we demonstrate that the present-day energy density of the produced chiral GWs peaks at a frequency of $\sim 100$ GHz, and the corresponding characteristic strain can be sensitive to current and future missions designed to detect high-frequency GWs.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2025)·5 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.