Thu·Mar 27, 2025Thursday·March 27, 2025

1. 01*

   Axion dissipation in conductive media and neutron star superradiance

   Thomas F.M. Spieksma🇩🇰 · Enrico Cannizzaro🇵🇹

   In axion electrodynamics, magnetic fields enable axion-photon mixing. Recent proposals suggest that rotating, conductive plasmas in neutron star magnetospheres could trigger axion superradiant instabilities -- an intriguing idea, given that such instabilities are typically associated with rotating black holes. In this work, we extend these investigations by properly incorporating plasma dynamics, particularly the plasma-induced photon effective mass, which suppresses the axion-photon mixing. Using two toy models for the conductive regions in the magnetosphere and accounting for fluid dynamics in both the frequency and time domain, we show that typical astrophysical plasma densities strongly inhibits the axionic instability. While our results assumes flat spacetime, the conclusions also apply to axion bound states in curved spacetimes, making neutron star superradiance less viable than previously thought. As a byproduct of our work, we provide a detailed description of axion electrodynamics in dissipative plasmas and uncover phenomena such as low-frequency axion "tails" and axion-induced electrostatic fields in dense plasmas.

   hep-phastro-ph.HEgr-qcJCAP(2025)·4 citations
2. 02*

   Two or three things particle physicists (mis)understand about (pre)heating

   Basabendu Barman🇮🇳 · Nicolás Bernal🇦🇪 · Javier Rubio🇪🇸

   The transition from the end of inflation to a hot, thermal Universe, commonly referred to as (re)heating, is a critical yet often misunderstood phase in early Universe cosmology. This short review aims to provide a comprehensive, conceptually clear, and accessible introduction to the physics of (re)heating, tailored to the particle physics community. We critically examine the standard Boltzmann approach, emphasizing its limitations in capturing the intrinsically non-perturbative and non-linear dynamics that dominate the early stages of energy transfer. These include explosive particle production, inflaton fragmentation, turbulence, and thermalization; phenomena often overlooked in perturbative treatments. We survey a wide range of theoretical tools, from Boltzmann equations to lattice simulations, clarifying when each is applicable and highlighting scenarios where analytic control is still feasible. Special attention is given to model-dependent features such as (pre)heating, the role of fermions, gravitational couplings, and the impact of multifield dynamics. We also discuss exceptional cases, including Starobinsky-like models and instant (pre)heating, where (re)heating proceeds through analytically tractable channels without requiring full non-linear simulations. Ultimately, this review serves both as a practical guide and a cautionary tale, advocating for a more nuanced and physically accurate understanding of this pivotal epoch within the particle physics community.

   hep-phastro-ph.COgr-qcNPB(2025)·31 citations
3. 03*

   The High-Temperature Limit of the SM(EFT)

   Mikael Chala🇪🇸 · Guilherme Guedes🇩🇪

   We derive the one-loop effective 3-dimensional Lagrangian that describes the high-temperature limit of the electroweak theory, to order $\mathcal{O}(g^6)$ in coupling constants $g$, including corrections due to Matsubara modes of both fermionic and bosonic degrees of freedom. We clarify certain aspects of the gauge-independence of physical parameters. We also extend the calculation to the Standard Model effective field theory, paving the way, in particular, for a precise study of the electroweak phase transition within this framework.

   hep-phhep-thJHEP(2025)·31 citations
4. 04*

   Testable dark matter solution within the seesaw mechanism

   A. Abada🇫🇷 · G. Arcadi🇮🇹 · M. Lucente🇮🇹 · S. Rosauro-Alcaraz🇮🇹

   The presence of a dark matter component in the Universe, together with the discovery of neutrino masses from the observation of the oscillation phenomenon, represents one of the most important open questions in particle physics today. A concurrent solution arises when one of the right-handed neutrinos, necessary for the generation of light neutrino masses, is itself the dark matter candidate. In this article, we study the generation of such a dark matter candidate relying solely on the presence of neutrino mixing. This tightly links the generation of dark matter with searches in laboratory experiments on top of the usual indirect dark matter probes. We find that the regions of parameter space producing the observed dark matter abundance can be probed indirectly with electroweak precision observables and charged lepton flavor violation searches. Given that the heavy neutrino masses need to lie at most around the TeV scale, probes at future colliders would further test this production mechanism.

   hep-phhep-exJHEP(2025)·7 citations
5. 05*

   Exploiting $\nu$-dependence of projected energy correlators in HICs

   Ankita Budhraja🇳🇱 · Balbeer Singh🇺🇸

   We extend the recently derived factorization formula for energy-energy correlators to study the analytic structure of general $\nu$-point projected energy correlators in heavy ion collisions. The $\nu$-point projected energy correlators (or, $\nu$-correlators) are an analytically continued family of the integer $N$-point projected energy correlators, which probe correlations between $N$ final-state particles. By tracking the largest separation ($\chi$) between the $N$ particles, in vacuum, their structure is closely related to the DGLAP splitting functions and exhibits a classical scaling behavior $\sim 1/\chi$ which is modified by resummation through the anomalous dimensions. We show that, in a thermal medium, the $\nu$-correlators display non-trivial angular scaling already at the leading order in perturbation theory. We find that for non-integer values, particularly $\nu <1$, medium-induced jet function is enhanced compared to $\nu >1$. This is particularly manifested in the ratios of $\nu$-correlators with respect to the two-point energy correlator which encode an intrinsic angular information for $\nu <1$ when compared to large $\nu$ values. Moreover, for small-$\nu$ values, the $\nu$-correlators appear to saturate at $\nu =0.01$. We further confirm our leading-order numerical computations against simulated events from JEWEL for the parton level production cross-section. Finally, we qualitatively discuss the effect of BFKL resummation for various values of $\nu$.

   hep-phnucl-exnucl-thPLB(2026)·10 citations
6. 06*

   Nucleon Energy Correlators for the Odderon

   Heikki Mäntysaari🇫🇮 · Yossathorn Tawabutr🇫🇮 · Xuan-Bo Tong🇫🇮

   We investigate the T-odd nucleon energy correlator (NEC) at small $x$ and establish its connection with the spin-dependent odderon. Probing the T-odd NEC involves measuring a single transverse spin asymmetry (SSA) for the energy pattern in the target fragmentation region in deep inelastic scattering. We find that while the inclusive energy pattern results in a vanishing SSA, a nonzero SSA emerges when restricting the measurement to charged hadrons, which are directly measured in tracking detectors. To describe this effect, we introduce the track-based NEC and evaluate its small-$x$ limit from fracture functions using the energy sum rule. The resulting SSA exhibits an opposite sign between positively and negatively charged hadrons, providing a clear experimental signature of the odderon. Furthermore, by incorporating charge weighting into the NEC, we construct a C-odd tag in the final state, eliminating potential contamination from C-even gluonic contributions. Our results demonstrate that these track-based energy-pattern observables offer a clean and sensitive probe for unveiling odderon dynamics at the future electron-ion collider.

   hep-phnucl-thPRD(2025)·21 citations
7. 07*

   Hidden charmed decays of $X(3872)$ within the $D{\bar{D}}^{\ast }$ molecular framework

   Hao-Dong Cai🇨🇳 · Zhao-Sai Jia🇨🇳 · Gang Li🇨🇳 · Shi-Dong Liu🇨🇳

   The dipionic transition of the $X(3872)$ to the ${\eta }_c$ was investigated using an effective Lagrangian approach. In this study, the $X(3872)$ was assumed to be a $D{\bar{D}}^{\ast }+\text{c.c.}$ bound state with the quantum numbers $J^{PC}=1^{++}$ and to decay via triangle and box loops. It is found that the partial decay widths arising from the box loops are one order of magnitude greater than those from the triangle ones. The decay widths are model-dependent, as characterized by the cutoff parameter introduced in the form factor. Moreover, the charged and neutral $D{\bar{D}}^{\ast }$ configurations of the $X(3872)$ and its mass also influence the decay widths. With our model parameters, the decay widths for the $X(3872)\to {\pi }^{+}{\pi }^{-}{\eta }_c$ can reach up to several tens of keV. We hope that the current calculations within the molecular interpretation will be helpful for the future experiments.

   hep-phPRD(2025)·8 citations
8. 08*

   Proton Spin Decomposition via QCD Sum Rules

   HyungJoo Kim🇯🇵 · Philipp Gubler🇯🇵 · Chihiro Sasaki🇵🇱

   We present a novel approach for investigating the spin structure of hadrons based on the two-point function in quantum field theory. In a rotating frame, we derive two independent expressions of the two-point function and identify their equivalence, which allows for a complete decomposition of the total spin of a composite system into the angular momenta of its constituent particles. Applying this approach to the proton, we analyze its spin structure in the massless quark limit. Our results indicate that the quark spin contribution accounts for approximately 27$\%$ of the total proton spin at a low-energy scale, significantly deviating from the prediction of the non-relativistic quark model.

   hep-phnucl-thPLB(2025)·2 citations
9. 09*

   Constraints on Velocity and Spin Dependent Exotic Interaction at the Millimeter Scale with a Diamagnetic-levitated Force Sensor

   Kenan Tian🇨🇳 · Yuanji Sheng🇨🇳 · Rui Li🇨🇳 · Lei Wang🇨🇳 · Peiran Yin🇨🇳 · Shaochun Lin🇨🇳 · Dingjiang Long🇨🇳 · Chang-Kui Duan🇨🇳 · Xi Kong🇨🇳 · Pu Huang🇨🇳 · Jiangfeng Du🇨🇳

   Light bosons, beyond the standard model and as prominent candidates for dark matter, can mediate velocity and spin dependent exotic interaction between electron spins and nucleons. At short ranges, it remains an open challenge to test this exotic interaction with high precision. Here, we present a method based on diamagnetic-levitated force sensor to detect the exotic interaction at the millimeter scale. Improved constraints for the coupling $g_A^e{g}_V^N$ are established, within the force range spanning from 0.15 mm to 1.5 mm. And the constraint $|g_A^e{g}_V^N|\le 4.39\times 10^{-26}$ at $\lambda$ = 0.5 mm at the $95\%$ confidence level, significantly surpasses previous results by more than three orders of magnitude. The diamagnetic levitation force measurement system developed here can also be repurposed to probe other exotic spin-dependent interactions, such as the exotic spin-spin interaction. This system provides a platform for the exploration of dark matter.

   hep-phquant-phPRL(2025)·6 citations
10. 10*

    Effect of $\alpha$-clusters on particle production in O$-$O and p$-$O collisions at LHC energies

    Deependra Sharma🇮🇳 · Arpit Singh🇮🇳 · Md. Samsul Islam🇮🇳 · Basanta Nandi🇮🇳 · Sadhana Dash🇮🇳

    In the present work, O$-$O collisions at $\sqrt{s_{NN}}$ = 7 TeV and p$-$O collisions at $\sqrt{s_{NN}}$ = 9.9 TeV are studied using PYTHIA8/Angantyr model for heavy-ion collisions. The theoretically predicted $\alpha$-cluster structure of oxygen nucleus is implemented in the model to investigate the effect of initial configuration of oxygen nucleus on final state observables. The results obtained from $\alpha$-cluster structure are compared with those obtained from Woods-Saxon nuclear charge density distribution. The Angantyr model simulation showed that the radial distribution of oxygen nucleus in $\alpha$-cluster configuration is more compact in comparison to the Woods-Saxon distribution. The results on charged and identified particle pseudorapidity distribution is obtained in the two initial state configuration of the oxygen nucleus. The results demonstrated that the effect of initial geometrical configuration is more distinct in the non-central collisions in comparison to the central collisions for both O$-$O and p$-$O collisions.

    hep-phnucl-thPRC(2025)·9 citations
11. 11*

    Four-loop anomalous dimension of flavor non-singlet twist-two operator of general Lorentz spin in QCD: zeta(3) term

    B.A. Kniehl🇩🇪 · V.N. Velizhanin🇩🇪

    We consider the anomalous dimension of the flavor non-singlet twist-two quark operator of arbitrary Lorentz spin N at four loops in QCD and construct its contribution proportional to zeta(3) in analytic form by applying advanced methods of number theory on the available knowledge of low-N moments. In conjunction with similar results on the zeta(5) and zeta(4) contributions, this completes our knowledge of the transcendental part of the considered anomalous dimension. This also provides important constraints on the as-yet elusive all-N form of the rational part. Via Mellin transformation, we thus obtain the exact functional form in x of the respective piece of the non-singlet Dokshitzer-Gribov-Lipatov-Altarelli-Parisi splitting function at four loops. This allows us to appreciably reduce the theoretical uncertainty in the approximation of that splitting function otherwise amenable from the first few low-N moments.

    hep-phhep-thPRL(2025)·11 citations
12. 12*

    Exploring the Dark Universe: A European Strategy for Axions and other WISPs Discovery

    Deniz Aybas🇹🇷 · Francesca Calore🇫🇷 · Michele Cicoli🇮🇹 · María Benito🇪🇪 · Arturo de Giorgi🇬🇧 · Amelia Drew🇮🇹 · Silvia Gasparotto🇪🇸 · Claudio Gatti🇮🇹 · Maurizio Giannotti🇪🇸 · Marco Gorghetto🇩🇪 · Mathieu Kaltschmidt🇪🇸 · Marin Karuza🇭🇷 and 8 other authors

    Axions and other very weakly interacting slim (with $m<$ 1 GeV) particles (WISPs) are a common feature of several extensions of the Standard Model of Particle Physics. The search of WISPs was already recommended in the last update of the European strategy on particle physics (ESPP). After that, the physics case for WISPs has gained additional momentum. Indeed, WISPs may provide a new paradigm to explain the nature of dark matter and puzzling astrophysical and particle physics observations. This document briefly summarizes current searches for WISPs and the perspectives in this research field for the next decade, ranging from their theoretical underpinning, over their indirect observational consequences in astrophysics, to their search in laboratory experiments. It is stressed that in Europe a rich, diverse, and low-cost experimental program is already underway with the potential for one or more game-changing discoveries. In this context, it is also reported the role of the EU funded COST Action ''Cosmic WISPers in the Dark Universe: Theory, astrophysics, and experiments'' (CA21106, https://www.cost.eu/actions/CA21106) in coordinating and supporting WISPs searches in Europe, shaping a roadmap to track the strategy to guarantee a European leadership in this field of research. This document has been submitted in March 2025 as an input to the update process of the ESPP.

    hep-phastro-ph.HEhep-exhep-th4 citations
13. 13*

    Gravitational $p\to {\Delta }^{+}$ transition form factors in chiral perturbation theory

    Bao-Dong Sun🇩🇪

    The proton to ${\Delta }^{+}$ resonance transitional gravitational form factors are calculated to leading one-loop order using chiral perturbation theory in our recent work [1]. We take into account the leading electromagnetic and strong isospin-violating effects to obtain non-vanishing contributions. The loop contributions to the transition form factors are found to be free of power-counting violating pieces, which is consistent with the absence of tree-level diagrams at the considered order. Our results involve no free parameters and can be regarded as predictions of chiral perturbation theory.

    hep-phPoS(2026)·1 citation
14. 14*

    Single-inclusive hadron production in electron-positron annihilation at next-to-next-to-next-to-leading order in QCD

    Chuan-Qi He🇨🇳 · Hongxi Xing🇨🇳 · Tong-Zhi Yang🇨🇭 · Hua Xing Zhu🇨🇳

    Single-inclusive hadron production in electron-positron annihilation (SIA) represents the cleanest process for investigating the dynamics of parton hadronization, as encapsulated in parton fragmentation functions. In this letter, we present, for the first time, the analytical computation of Quantum Chromodynamics (QCD) corrections to the coefficient functions for SIA at next-to-next-to-next-to-leading order (N${}^3$LO) accuracy, achieving the highest precision to date for hadron production processes. Utilizing the BaBar measurement as a benchmark, we assess the phenomenological implications of this high-precision calculation. Our findings demonstrate a substantial reduction in scale uncertainties at N${}^3$LO and offer an improved description of the experimental data compared to lower-order calculations. This advancement underscores the importance of higher-order corrections in achieving a more accurate understanding of hadronization processes.

    hep-phPRL(2025)·22 citations
15. 15*

    Chiral Solitons

    Herbert Weigel🇿🇦

    Generalizing quantum chromodynamics (QCD) from three to arbitrarily many color degrees of freedom suggests that baryons can be described as solitons in an effective meson theory whose interaction strength decreases with the number of colors. The exact form of that theory is unknown, but at low energies chiral symmetry and its breaking are considered as the construction recipes for modeling the theory. The Skyrmion is a static, localized solution in a non-linear field theory for pions and it is the most prominent version of a soliton in a chirally symmetric meson theory. Upon quantization it reproduces the spectrum of the low-lying baryons and their static properties reasonably well. Extending that theory by vector mesons improves on the agreement between predicted and empirical data. Chiral solitons within models for the quark flavor dynamics facilitate the investigation of nucleon structure functions. Here we provide a pedagogical overview of these facets.

    hep-phhep-thnucl-th0 citations
16. 16*

    Dyons, Instantons, Baryons and AdS/QCD

    Eberhard Klempt🇩🇪

    Dmitri Diakonov has played a significant role in identifying the degrees of freedom underlying hadron spectroscopy. His contributions are discussed with a view on recent developments.

    hep-phActa Phys.Polon.B(2025)·0 citations
17. 17*

    Electroweak Precision Data as a Gateway to Light Higgsinos

    Natsumi Nagata🇯🇵 · Genta Osaki🇯🇵

    We investigate the prospects of probing weak-scale higgsinos through electroweak precision measurements at a future $e^{+}{e}^{-}$ collider. In the Minimal Supersymmetric Standard Model, higgsinos mix with winos and binos after electroweak symmetry breaking, forming charginos and neutralinos. These states contribute to electroweak precision observables, which can be measured with high accuracy at future $e^{+}{e}^{-}$ colliders. Their contributions depend on the mixing structure, as evidenced by the generation of the oblique parameters $\hat{S}$ and $\hat{T}$, in addition to the $W$ and $Y$ parameters, which arise even in the absence of mixing. We demonstrate that higgsinos with masses up to $\sim 500\mathrm{GeV}$ can be probed through future electroweak precision experiments, highlighting their significance in probing weak-scale supersymmetry.

    hep-phJHEP(2025)·6 citations
18. 18*

    EERAD3 version 2: QCD corrections in hadronic colour-singlet decays

    Benjamin Campillo Aveleira🇩🇪 · Aude Gehrmann-De Ridder🇨🇭 · Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Gudrun Heinrich🇩🇪 · Christian T. Preuss🇩🇪

    We present a major update of the publicly available EERAD3 package to calculate perturbative corrections in the strong coupling in hadronic Higgs and $Z$-boson decays. We describe the theoretical framework underlying the numerical implementation and provide a guide to the usage of the program.

    hep-phhep-exSciPost Phys.Codeb.(2025)·11 citations
19. 19*

    Constraining CPT-odd electromagnetic chiral parameters with pulsar timing

    Filipe S. Ribeiro🇧🇷 · Pedro D. S. Silva🇧🇷 · Manoel M. Ferreira Jr🇧🇷

    The arrival time of electromagnetic signals traveling in chiral cosmic media is investigated in the context of Maxwell-Carroll-Field-Jackiw electrodynamics. Considering the interstellar medium (ISM) as a cold, ionized, chiral plasma, we derive the time delay between two traveling signals, expressed in terms of a modified dispersion measure (DM) which receives additional contribution from the chiral parameters. Faraday rotation angle is also addressed in this chiral plasma scenario, yielding modified rotation measures (RM). Using DMs data from five pulsars, we establish constraints on the chiral parameter magnitude at the order of $10^{-23}$ -- $10^{-22}$ GeV. On the other hand, the Faraday rotation retrieved from RM measurements implied upper constraints as tight as $10^{-36}$ GeV.

    hep-phhep-thPRD(2025)·5 citations
20. 20*

    Functional methods for hadron spectroscopy

    Gernot Eichmann🇦🇹 · Christian S. Fischer🇩🇪 · Joshua Hoffer🇩🇪

    We summarize recent results for four-quark states with hidden and open flavor obtained from a four-quark Bethe-Salpeter/Faddeev-Yakubowsky equation. The approach dynamically predicts the leading internal two-body clusters such as meson-meson, hadroquarkonium or diquark-antidiquark components. For hidden-flavor states, the meson-meson or hadroquarkonium configurations are dominant, while the diquark contributions are small. For open-flavor states, the situation is different and depends on the quark content: The $T_{bb}^{-}$ is a mixture of various components, where the diquark-antidiquark components are dominant, whereas the $T_{cc}^{+}$ is practically entirely dominated by $D{D}^{\ast }$ due to its proximity to the threshold. We also provide details on the analytic continuations and extrapolations to extract states above thresholds.

    hep-phPoS(2025)·4 citations
21. 21*

    Out-of-equilibrium chiral condensate in AdS/QCD

    Floriana Giannuzzi🇮🇹 · Stefano Nicotri🇮🇹

    We study the chiral condensate at finite temperature in AdS/QCD in a time-dependent background, in which the position of the black-hole horizon $z_h$ changes with time, producing an increasing or decreasing temperature. Conformal invariance is broken, as in the soft-wall model, by a static quadratic dilaton. Two different scenarios are analysed: in the first a general power-law time dependence is assumed for $z_h$, while in the second the energy-momentum tensor at late times reproduces the one found in viscous hydrodynamics. Depending on the rate at which the system evolves, the transition shifts toward lower temperatures. If the chiral condensate is far from equilibrium at low temperatures, oscillations around its equilibrium value are observed before thermalization. A prethermalization stage is found in the chiral limit if the initial condition is set at a temperature close to the critical one. In the hydrodynamic setup the evolution of the medium is slow enough, and the chiral condensate soon matches the equilibrium curve.

    hep-phPRD(2025)·3 citations
22. 22*

    Freeze-in and freeze-out production of Higgs portal Majorana fermionic dark matter during and after reheating

    Rajesh Mondal🇮🇳 · Sourav Mondal🇮🇳 · Toshifumi Yamada🇯🇵

    In this paper, we investigate the production of Majorana fermionic dark matter (DM) via the Higgs portal, considering both freeze-in and freeze-out mechanisms during and after the post-inflationary reheating phase. We assume that the Universe is reheated through the decay of the inflaton ($\varphi$) into a pair of fermions $f$ and $\bar{f}$ via the interaction $y\varphi \bar{f}f$, where $y$ is the dimensionless Yukawa coupling. Our analysis focuses on how the non-standard evolution of the Hubble expansion rate and the thermal bath temperature during reheating influence DM production. Additionally, we examine the impact of electroweak symmetry breaking (EWSB), distinguishing between scenarios where DM freeze-in or freeze-out occurs before or after EWSB. We further explore the viable DM parameter space and its compatibility with current and future detection experiments, including XENONnT, LUX-ZEPLIN (LZ), XLZD, and collider searches. Moreover, we incorporate constraints from the Lyman-$\alpha$ bound to ensure consistency with small-scale structure formation.

    hep-phastro-ph.COhep-thPRD(2026)·16 citations
23. 23*

    Stabilizing Neural Likelihood Ratio Estimation

    Fernando Torales Acosta🇺🇸 · Tanvi Wamorkar🇺🇸 · Vinicius Mikuni🇺🇸 · Benjamin Nachman🇺🇸

    Likelihood ratios are used for a variety of applications in particle physics data analysis, including parameter estimation, unfolding, and anomaly detection. When the data are high-dimensional, neural networks provide an effective tools for approximating these ratios. However, neural network training has an inherent stochasticity that limits their precision. A widely-used approach to reduce these fluctuations is to train many times and average the output (ensembling). We explore different approaches to ensembling and pretraining neural networks for stabilizing likelihood ratio estimation. For numerical studies focus on unbinned unfolding with OmniFold, as it requires many likelihood ratio estimations. We find that ensembling approaches that aggregate the models at step 1, before pushing the weights to step 2 improve both bias and variance of final results. Variance can be further improved by pre-training, however at the cost increasing bias.

    hep-phhep-exphysics.data-an5 citations
24. 24*

    Feasibility of measuring the speed of sound of the quark-gluon plasma from the multiplicity and mean $p_T$ of ultracentral heavy-ion collisions

    Lorenzo Gavassino🇺🇸 · Henry Hirvonen🇺🇸 · Jean-François Paquet🇺🇸 · Mayank Singh🇺🇸 · Gabriel Soares Rocha🇺🇸

    The mean transverse momentum $⟨p_T⟩$ of hadrons has been observed experimentally and in numerical simulations to have a power-law dependence on the hadronic multiplicity $N$ in ultracentral relativistic heavy-ion collisions: $⟨p_T⟩\propto N^{b_{\mathrm{UC}}}$. It has been put forward that this exponent $b_{\mathrm{UC}}$ is the speed of sound of quark-gluon plasma measured at a temperature determined from $⟨p_T⟩$. We study step by step the connection between (i) the energy and entropy of hydrodynamic simulations and (ii) experimentally measurable observables. We show that an argument based on energy and entropy should yield an exponent equal to the pressure over energy density $P/\epsilon$, rather than the speed of sound $c_s^2$; however, we also observe that $⟨p_T⟩$ and $N$ are not sufficiently accurate proxies for the energy and entropy to make this possible in practice. From simulations, we find that the exponent $b_{\mathrm{UC}}$ is significantly different whether the ''effective volume'' is strictly constant or not, a condition that cannot be enforced experimentally. Additional tests using a modified equation of state find that the exponent $b_{\mathrm{UC}}$ exhibits a variable degree of correlations with the speed of sound and with $P/\epsilon$, but is not an accurate measurement of either quantity in general.

    hep-phnucl-thPRC(2025)·6 citations
25. 25*

    Inclusive hadroproduction of charmonia-bottomonia pairs in the CGC framework

    M. Siddikov🇨🇱

    In this preprint we analyze the inclusive hadroproduction of heavy charmonia-bottomonia pairs in the Color Glass Condensate framework in the dilute-dense approximation. The production mechanisms can be classified by number of gluons emitted from projectile as Single- and Double Parton Scattering. We analyzed separately both types of contributions and evaluated the corresponding impact factors in the leading order in strong coupling ${\alpha }_s$. For the Double Parton Scattering the impact factors factorize into a product of impact factors of single charmonia and bottomonia production cross-sections, and the cross-section in the large-$N_c$ limit reduces to the well-known pocket formula. For the Single Parton Scattering we found that the cross-section of the process is sensitive to dipole, quadrupole, sextupole and octupole scattering amplitudes (correlators of Wilson lines), thus opening possibility to study phenomenologically these novel objects. We also made phenomenological estimates of the cross-sections in the dilute approximation and found that the suggested approach provides a fair qualitative description of the LHCb data for $J/\psi +{\rm Y}(1S)$ production.

    hep-phPRD(2025)·2 citations
26. 26*

    Conditional Deep Generative Models for Simultaneous Simulation and Reconstruction of Entire Events

    Etienne Dreyer🇮🇱 · Eilam Gross🇮🇱 · Dmitrii Kobylianskii🇮🇱 · Vinicius Mikuni🇺🇸 · Benjamin Nachman🇺🇸

    We extend the Particle-flow Neural Assisted Simulations (Parnassus) framework of fast simulation and reconstruction to entire collider events. In particular, we use two generative Artificial Intelligence (genAI) tools, continuous normalizing flows and diffusion models, to create a set of reconstructed particle-flow objects conditioned on truth-level particles from CMS Open Simulations. While previous work focused on jets, our updated methods now can accommodate all particle-flow objects in an event along with particle-level attributes like particle type and production vertex coordinates. This approach is fully automated, entirely written in Python, and GPU-compatible. Using a variety of physics processes at the LHC, we show that the extended Parnassus is able to generalize beyond the training dataset and outperforms the standard, public tool Delphes.

    ↳ hep-exhep-phPRD(2026)·10 citations
27. 27*

    A Linear Collider Vision for the Future of Particle Physics

    H. Abramowicz · E. Adli · F. Alharthi · M. Almanza-Soto · M.M. Altakach · W. Altmannshofer · S. Ampudia Castelazo · D. Angal-Kalinin · J.A. Anguiano · R.B. Appleby · O. Apsimon · A. Arbey and 439 other authors

    In this paper we review the physics opportunities at linear $e^{+}{e}^{-}$ colliders with a special focus on high centre-of-mass energies and beam polarisation, take a fresh look at the various accelerator technologies available or under development and, for the first time, discuss how a facility first equipped with a technology mature today could be upgraded with technologies of tomorrow to reach much higher energies and/or luminosities. In addition, we will discuss detectors and alternative collider modes, as well as opportunities for beyond-collider experiments and R\&D facilities as part of a linear collider facility (LCF). The material of this paper will support all plans for $e^{+}{e}^{-}$ linear colliders and additional opportunities they offer, independently of technology choice or proposed site, as well as R\&D for advanced accelerator technologies. This joint perspective on the physics goals, early technologies and upgrade strategies has been developed by the LCVision team based on an initial discussion at LCWS2024 in Tokyo and a follow-up at the LCVision Community Event at CERN in January 2025. It heavily builds on decades of achievements of the global linear collider community, in particular in the context of CLIC and ILC.

    ↳ hep-exhep-phphysics.acc-phphysics.ins-detEur.Phys.J.ST(2026)·118 citations
28. 28*

    Quantum circuits for simulating neutrino propagation in matter

    Sandeep Joshi🇮🇳 · Garima Rajpoot🇮🇳 · Prashant Shukla🇮🇳

    Quantum simulation of particle phenomena is a rapidly advancing field of research. With the widespread availability of quantum simulators, a given quantum system can be simulated in numerous ways, offering flexibility in implementation and exploration. Here, we perform quantum simulation of neutrino propagation in matter, a phenomenon that plays a crucial role in neutrino oscillations. We present quantum circuits with novel gate arrangements to simulate neutrino propagation in both constant and varying matter density profiles. The oscillation probabilities are determined by encoding and measuring the qubit states in the neutrino flavor basis, showing excellent agreement with theoretical predictions.

    ↳ quant-phhep-phPhys.Scripta(2025)·5 citations
29. 29*

    Magnetodynamic Characteristics and QGP Energy Dissipation in RMHD Framework with Relativistic Heavy-Ion Collisions

    Huang-Jing Zheng🇨🇳 · Sheng-Qin Feng🇨🇳

    Relativistic heavy-ion collisions generate ultra-strong magnetic fields that interact with the quark-gluon plasma (QGP), a key focus of high-energy physics research.This study investigates QGP energy density evolution under time-dependent magnetic fields within a (1 +1)D relativistic magnetohydrodynamic (RMHD) framework integrated with Bjorken flow. Three magnetic field temporal evolution models (Type-1,Type-2,Type-3) are analyzed for two different equations of state: (1) $p=c_s^{2}e$, and (2)$p=c_s^{2}e-2MB$ incorporating a temperature-dependent magnetic susceptibility derived from lattice QCD. Results show that stronger magnetic fields consistently suppress QGP energy density decay,with suppression magnitude dependent on the magnetic field's temporal profile. Ultra-relativistic fluids exhibit slowed energy decay due to magnetic pressure counteracting hydrodynamic expansion.In contrast,magnetized conformal fluids display faster energy dissipation under identical conditions, arising from the synergistic effect of enhanced magnetic fluid coupling,increased energy dissipation during interaction,and QGP's perfect fluid expansion at elevated temperatures.Temperature-dependent magnetic susceptibility reveals a transition from diamagnetic (confined phase) to paramagnetic (deconfined QGP phase) behavior, introducing a feedback mechanism that strengthens energy retention at higher temperatures. This work clarifies the interplay between magnetic field dynamics,QCD phase structure, and hydrodynamic expansion, providing key observational signatures for distinguishing fluid types in heavy-ion collisions and advancing realistic modeling of magnetized QGP.

    ↳ nucl-thhep-phParticles(2026)·2 citations
30. 30*

    Sensitivity of Hybrid Particle Detectors to the Energy Spectra of Air Shower Components

    P. Assis🇵🇹 · R. Conceição🇵🇹 · P. J. Costa🇵🇹 · M. Freitas🇵🇹 · B. Tomé🇵🇹

    Measuring the energy spectrum of air shower components crucial for understanding primary cosmic rays and the physical processes governing their interactions in the atmosphere. However, accurately measuring the energy of shower particles reaching the ground is challenging due to the inherent simplicity of typical cosmic ray experiments. This study takes advantage of a hybrid detector station and introduces an analysis for assessing the energy spectra of air shower components. The station is composed of a scintillator surface detector (SSD), a water-Cherenkov detector (WCD), and resistive plate chambers (RPCs). Our results demonstrate that the combination of data from these detectors enables precise assessment of the energy spectrum of electromagnetic particles and low-energy muons, independent of potential detector ageing effects.

    ↳ hep-exhep-phJCAP(2025)·1 citation
31. 31*

    Rotational Metric: A Solution to Einstein's Clock-Rate Problem and Its Magnetospheric Applications

    Zhen Zhang🇨🇳 · Rui Zhang🇨🇳

    The rotational metric provides an exact solution to Einstein's clock-rate problem in curved spacetime, specifically, whether time flows more slowly at the equator of a compact object such as a neutron star than at its poles. It features a curvature singularity, an event horizon, a potentially evolving ergosphere, a rigidly-rotating normal space, and two stationary limit surfaces. Although derived from the Schwarzschild metric through rotational transformations, it includes an additional ergosphere. Given the equivalence of inertia and gravity, this demonstrates how non-inertial transformations, such as rotational transformations, can introduce new spacetime structures into a gravitational system. In particular, the additional physical degrees of freedom carried by rotational transformations are `eaten' by the gravitational system to form an additional ergosphere. Furthermore, the rotational metric effectively models a rigidly-rotating gravitational system and is applicable for describing rotationally-induced gravitational effects in various rotating magnetospheres.

    ↳ gr-qcastro-ph.HEastro-ph.SRhep-ph+1CPC(2025)·1 citation
32. 32*

    Experimental Signatures for Identifying Distinct Origins of Color Field Generation

    Subramanya Bhat K. N.🇮🇳 · Amita Das🇮🇳 · Bhooshan Paradkar🇮🇳 · V Ravishankar🇮🇳

    Signatures for non-abelian dynamics have long been central to QCD and QGP. Equally important are they in spin systems and laser-plasma interactions, where they emerge as effective interactions. Distinguishing experimentally gauge inequivalent sources (and hence potentials) that produce the same field tensor is one major task in this endeavour. As a step in this direction, this paper investigates how physically distinct sources which produce the same color electric field (uniform and constant) may be distinguished experimentally in a gauge-invariant manner. We first study the motion of a test particle in such fields and show that the resultant trajectories are counterintuitive. We then examine the radiation emitted - both gluonic and photonic and show that each source (independent non-abelian configuration) leaves a unique signature in the energy spectra, laying the ground for application to specific physical systems.

    ↳ physics.plasm-phcond-mat.otherhep-phhep-th+1New J.Phys.(2025)·1 citation
33. 33*

    Effects of quark core sizes of baryons in neutron star matter

    Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸

    We describe the quark substructure of hadrons and the equation of state of high density neutron star matter by using the Nambu$-$Jona-Lasinio (NJL) model, which is an effective quark theory based on QCD. The interaction between quarks fully respects the chiral and flavor symmetries. Guided by the success of various low energy theorems, we assume that the explicit breaking of these symmetries occurs only via the current quark masses, and all other symmetry breakings are of dynamical nature. In order to take into account the effects of the finite quark core sizes of the baryons on the equation of state, we make use of an excluded volume framework which respects thermodynamic consistency. The effects generated by the swelling quark cores generally act repulsively and lead to an increase of the pressure with increasing baryon density. On the other hand, in neutron star matter they also lead to a decrease of the density window where hyperons appear, because it becomes energetically more favorable to convert the faster moving nucleons into hyperons. Our quantitative analysis shows that the net effect of the excluded volume is too small to solve the long standing "hyperon puzzle," which is posed by the large observed masses of neutron stars. Thus the puzzle persists in a relativistic effective quark theory which takes into account the short range repulsion between baryons caused by their finite and swelling quark core sizes in a phenomenological way.

    ↳ nucl-thhep-phSymmetry(2025)·6 citations
34. 34*

    Aspects of canonical differential equations for Calabi-Yau geometries and beyond

    Claude Duhr🇩🇪 · Sara Maggio🇩🇪 · Christoph Nega🇩🇪 · Benjamin Sauer🇩🇪 · Lorenzo Tancredi🇩🇪 · Fabian J. Wagner🇩🇪

    We show how a method to construct canonical differential equations for multi-loop Feynman integrals recently introduced by some of the authors can be extended to cases where the associated geometry is of Calabi-Yau type and even beyond. This can be achieved by supplementing the method with information from the mixed Hodge structure of the underlying geometry. We apply these ideas to specific classes of integrals whose associated geometry is a one-parameter family of Calabi-Yau varieties, and we argue that the method can always be successfully applied to those cases. Moreover, we perform an in-depth study of the properties of the resulting canonical differential equations. In particular, we show that the resulting canonical basis is equivalent to the one obtained by an alternative method recently introduced in the literature. We apply our method to non-trivial and cutting-edge examples of Feynman integrals necessary for gravitational wave scattering, further showcasing its power and flexibility.

    ↳ hep-thhep-phmath.AGJHEP(2025)·51 citations
35. 35*

    The Scalar Size of the Pion from Lattice QCD

    Konstantin Ottnad🇩🇪 · Georg von Hippel🇩🇪

    We present a lattice QCD calculation of the pion scalar form factor and associated radii with fully controlled systematics. Lattice results are computed on a large set of 17 gauge ensembles with $N_f=2+1$ Wilson Clover-improved sea quarks. These ensembles cover four values of the lattice spacing between $a=0.049\mathrm{fm}$ and $a=0.086\mathrm{fm}$, a pion mass range of $130-350\mathrm{MeV}$ and various physical volumes. A precise determination of the notorious quark-disconnected contributions facilitates an unprecedented momentum resolution for the form factor, particularly on large and fine ensembles in the vicinity of physical quark mass. A large range of source-sink separations $1.0\mathrm{fm}\lesssim t_{\mathrm{sep}}\lesssim 3.25\mathrm{fm}$ is used to reliably extract the relevant ground state matrix elements at vanishing and non-vanishing momentum transfer. This allows us for the first time to obtain the scalar radii from a $z$-expansion parametrization of the $Q^2$-dependence of the resulting form factors rather than a simple, linear approximation at small momentum transfer. The physical extrapolation for the radii is carried out using three-flavor NLO chiral perturbation theory to parametrize the quark mass dependence in terms of three low-energy constants, including the first lattice determination of $L_4^r$. Systematic uncertainties on the final results related to the ground state extraction, form factor parametrization as well as the physical extrapolation are accounted for via model averages based on the Akaike Information Criterion.

    ↳ hep-lathep-phPRD(2025)·2 citations
36. 36*

    Low-Energy Constants of Chiral Perturbation Theory from Pion Scalar Form Factors in $N_f=2+1$-Flavor Lattice QCD with Controlled Errors

    Georg von Hippel🇩🇪 · Konstantin Ottnad🇩🇪

    We determine the low-energy constants (LECs) $f_0$, $L_4^r$ and $L_5^r$ of SU(3) Chiral Perturbation Theory ($\chi$PT) from a lattice QCD calculation of the scalar form factors of the pion with fully controlled systematics. Lattice results are computed on a large set of $N_f=2+1$ gauge ensembles covering four lattice spacings $a\in [0.049,0.086]\mathrm{fm}$, pion masses $M_{\pi }\in [130,350]\mathrm{MeV}$, and various large physical volumes. By determining the notorious quark-disconnected contributions with unprecedented precision and using a large range of source-sink separations $t_{\mathrm{sep}}\in [1.0,3.25]\mathrm{fm}$, we are able for the first time to obtain the scalar radii from a $z$-expansion parameterization of the form factors rather than a simple linear approximation at small momentum transfer. The LECs are obtained from the physical extrapolation of the radii using NLO SU(3) NLO $\chi$PT to parameterize the quark mass dependence. Systematic uncertainties are estimated via model averages based on the Akaike Information Criterion. Our determination of $L_4^r$ is the first lattice determination to obtain a result not compatible with zero.

    ↳ hep-lathep-phPRL(2025)·3 citations
37. 37*

    Immortality through the dark forces: Dark-charge primordial black holes as dark matter candidates

    Jessica Santiago (National Taiwan University)🇹🇼 · Justin Feng (CEICO Prague)🇨🇿 · Sebastian Schuster (Stockholm University)🇸🇪 · Matt Visser (Victoria University of Wellington)🇳🇿

    The fact that no Hawking radiation from the final stages of evaporating primordial black holes (PBHs) has yet been observed places stringent bounds on their allowed contribution to dark matter. Concretely, for Schwarzschild PBHs, i.e., uncharged and non-rotating black holes, this rules out black hole masses of less than $10^{-15}{M}_{\odot }$. In this article, we propose that by including an additional 'dark' $U(1)$ charge one can significantly lower the PBHs' Hawking temperature, slowing down their evaporation process and significantly extending their lifetimes. With this, PBHs again become a viable option for dark matter candidates over a large mass range. We will explore in detail the effects of varying the dark electron (lightest dark charged fermion) mass and charge on the evaporation dynamics. For instance, we will show that by allowing the dark electron to have a sufficiently high mass and/or low charge, our approach suppresses both Hawking radiation and the Schwinger effect, effectively extending even the lifespan of PBHs with masses smaller than $10^{-15}{M}_{\odot }$ beyond the current age of the universe. We will finally present a new lower bound on the allowed mass range for dark-charged PBHs as a function of the dark electron charge and mass, showing that the PBHs' mass can get to at least as low as $10^{-24}{M}_{\odot }$ depending on the dark electron properties. This demonstrates that the phenomenology of the evaporation of PBHs is ill-served by a focus solely on Schwarzschild black holes.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-phPRD(2025)·10 citations
38. 38*

    Nuclear recoil detection with color centers in bulk lithium fluoride

    Gabriela A. Araujo🇨🇭 · Laura Baudis🇨🇭 · Nathaniel Bowden🇺🇸 · Jordan Chapman🇺🇸 · Anna Erickson · Mariano Guerrero Perez · Adam A. Hecht · Samuel C. Hedges🇺🇸 · Patrick Huber🇺🇸 · Vsevolod Ivanov · Igor Jovanovic🇺🇸 · Giti A. Khodaparast and 10 other authors

    We present initial results on nuclear recoil detection based on the fluorescence of color centers created by nuclear recoils in lithium fluoride. We use gamma rays, fast and thermal neutrons, and study the difference in responses they induce, showing that this type of detector is rather insensitive to gamma rays. We use light-sheet fluorescence microscopy to image nuclear recoil tracks from fast and thermal neutron interactions deep inside a cubic-centimeter sized crystal and demonstrate automated feature extraction in three dimensions using machine learning tools. The number, size, and topology of the events agree with expectations based on simulations with TRIM. These results constitute the first step towards 10-1000g scale detectors with single-event sensitivity for applications such as the detection of dark matter particles, reactor neutrinos, and neutrons.

    ↳ nucl-exhep-exhep-phphysics.ins-detEPJC(2026)·8 citations
39. 39*

    Detectability of the chiral gravitational wave background from audible axions with the LISA-Taiji network

    Hong Su🇨🇳 · Baoyu Xu🇨🇳 · Ju Chen🇨🇳 · Chang Liu🇨🇳 · Yun-Long Zhang🇨🇳

    The chiral gravitational wave background (GWB) can be produced by axion-like fields in the early universe. We perform parameter estimation for two types of chiral GWB with the LISA-Taiji network: axion-dark photon coupling and axion-Nieh-Yan coupling. We estimate the spectral parameters of these two mechanisms induced by axion and determine the normalized model parameters using the Fisher information matrix. For highly chiral GWB signals that we choose to analyze in the mHz band, the normalized model parameters are constrained with a relative error less than $6.7\%$ (dark photon coupling) and $2.2\%$ (Nieh-Yan coupling) at the one-sigma confidence level. The circular polarization parameters are constrained with a relative error around $21\%$ (dark photon coupling) and $6.2\%$ (Nieh-Yan coupling) at the one-sigma confidence level.

    ↳ astro-ph.COgr-qchep-phCommun.Theor.Phys.(2025)·10 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.