Mon·May 12, 2025Monday·May 12, 2025

1. 01*

   Fresh look at the diffuse ALP background from supernovae

   Francisco R. Candón🇪🇸 · Sougata Ganguly🇰🇷 · Maurizio Giannotti🇪🇸 · Tanmoy Kumar🇮🇳 · Alessandro Lella🇮🇹 · Federico Mescia🇮🇹

   Protoneutron stars, highly compact objects formed in the core of exploding supernovae (SNe), are powerful sources of axion-like particles (ALPs). In the SN core, ALPs are dominantly produced via nucleon-nucleon bremsstrahlung and pion conversion, resulting in an energetic ALP spectrum peaked at energies $\mathcal{O}(100)\mathrm{MeV}$. In this work, we revisit the diffuse ALP background, produced from all past core-collapse supernovae, and update the constraints derived from Fermi-LAT observations. Assuming the maximum ALP-nucleon coupling allowed by the SN 1987A cooling, we set the upper limit $g_{a\gamma \gamma }\lesssim 2\times 10^{-13}\mathrm{Ge}{\mathrm{V}}^{-1}$ for ALP mass $m_a\lesssim 10^{-10}\mathrm{eV}$, which is approximately a factor of two improvement with respect to the existing bounds. On the other hand, for $m_a\gtrsim 10^{-10}\mathrm{eV}$, we find that including pion conversion strengthens the bound on $g_{a\gamma \gamma }$, approximately by a factor of two compared to the constraint obtained from bremsstrahlung alone. Additionally, we present a sensitivity study for future experiments such as AMEGO-X, e-ASTROGAM, GRAMS-balloon, GRAMS-satellite, and MAST. We find that the expected constraint from MAST would be comparable to Fermi-LAT bound. However, SN 1987A constraint remains one order of magnitude stronger as compared to the bound derived from the current and future gamma-ray telescopes.

   hep-phastro-ph.HEPRD(2025)·9 citations
2. 02*

   The Electroweak Sphaleron Revisited: I. Static Solutions, Energy Barrier, and Unstable Modes

   Konstantin T. Matchev🇺🇸 · Sarunas Verner🇺🇸

   The electroweak sphaleron is a static, unstable solution of the Standard Model classical field equations, representing the energy barrier between topologically distinct vacua. In this work, we present a comprehensive updated analysis of the sphaleron using current Standard Model parameters with the physical Higgs boson mass of $m_H=125.1$ GeV and $m_W=80.4$ GeV, rather than the $m_H=m_W$ approximation common in earlier studies. The study includes: (i) a complete derivation of the $SU(2)\times U(1)$ electroweak Lagrangian and field equations without gauge fixing constraints, (ii) high-precision numerical solutions for the static sphaleron configuration yielding a sphaleron energy $E_{\mathrm{sph}}\simeq 9.1$ TeV, (iii) an analysis of the minimum energy path in field space connecting the sphaleron to the vacuum (a 1D potential barrier as a function of Chern-Simons number), and (iv) calculation of the sphaleron single unstable mode with negative eigenvalue ${\omega }_{-}^2=-2.7m_W^2$, providing analytical fits for its eigenfunction. We find that using the measured Higgs mass modifies the unstable mode frequency, with important implications for baryon number violation rates in both early universe cosmology and potential high-energy collider signatures. These results provide essential input for accurate lattice simulations of sphaleron transitions and precision calculations of baryon number violation processes.

   hep-phhep-thPRD(2025)·8 citations
3. 03*

   The Electroweak Sphaleron Revisited: II. Study of Decay Dynamics

   Konstantin T. Matchev🇺🇸 · Sarunas Verner🇺🇸

   We present a comprehensive analysis of electroweak sphaleron decay dynamics, employing both analytical techniques and high-resolution numerical simulations. Using a spherically symmetric ansatz, we reformulate the system as a $(1+1)$-dimensional problem and analyze its stability properties with current Standard Model parameters ($m_H=125.1$ GeV, $m_W=80.4$ GeV). We identify precisely one unstable mode with eigenvalue ${\omega }_{-}^2\simeq -2.7m_W^2$ and numerically evolve the full non-linear field equations under various initial conditions. Through spectral decomposition, we quantify the particle production resulting from the sphaleron decay. Our results demonstrate that the decay process is dominated by transverse gauge bosons, which constitute approximately 80% of the total energy and multiplicity, while Higgs bosons account for only 7-8%. On average, the sphaleron decays into 49 $W$ bosons and 4 Higgs bosons. The particle spectra consistently peak at momenta $k\sim 1-1.5m_W$, reflecting the characteristic size of the sphaleron. Remarkably, these properties remain robust across different decay scenarios, suggesting that the fundamental structure of the sphaleron, rather than specific triggering mechanisms, determines the decay outcomes. These findings provide distinctive experimental signatures of non-perturbative topological transitions in the electroweak theory, with significant implications for baryon number violation in the early universe and potentially for high-energy collider physics.

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

   A Physics Model for Origin of Life

   Paul Howard Frampton🇮🇹

   In this article, we attempt to convince the reader that the origin of life was such an exceptionally unlikely event that it probably has never occurred elsewhere. This involves an explicit calculation using the laws of physics which, while speculative, may encapsulate the essential science without knowledge of biological details. Making only physics, and no biology, assumptions about the origin of the first single celled organism (SCO) on Earth, we adopt methods of quantum tunnelling to make an estimate of the probability ${\mathcal{P}}_{SCO}$ for the origin of life. We argue that before the time $t_{SCO}$ laws of physics must suffice and assume a first-order phase transition which nucleates at the first SCO production. In the classical limit where Planck's constant vanishes $h\to 0$, ${\mathcal{P}}_{SCO}$ also vanishes and remains extremely small for the correct value of $h$. Thus quantum mechanics plays a central role in permitting life to form. We compare the resultant probability with the expected number of exoplanets in the Milky Way ($\sim 10^{12}$) and the Visible Universe ($\sim 10^{24}$) and conclude that the probability of extraterrestrial life in the Visible Universe is infinitesimal. This result suggests that the visible universe is a lonely place for humankind because extraterrestrial life will never be encountered.

   hep-phAm.J.Phys.Appl.(2025)·2 citations
5. 05*

   From oversimplified to overlooked: the case for exploring Rich Dark Sectors

   Asli Abdullahi🇪🇸 · Francesco Costa🇨🇿 · Andrea Giovanni De Marchi🇮🇹 · Alessandro Granelli🇮🇹 · Jaime Hoefken-Zink🇵🇱 · Matheus Hostert🇺🇸 · Michele Lucente🇮🇹 · Elina Merkel🇮🇹 · Jacopo Nava🇮🇹 · Silvia Pascoli🇮🇹 · Salvador Rosauro-Alcaraz🇮🇹 · Filippo Sala🇮🇹

   The Standard Model (SM) of particle physics provides a very successful description of fundamental particles and their interactions but it is incomplete, as neutrino masses, dark matter and the baryon asymmetry of the Universe indicate. In addition, the origin of masses and of the approximate fundamental symmetries call out for deeper explanations. The quest for a New SM Theory, that extends the SM to a more general theory, is ongoing. For decades the main focus has been on the TeV scale, but despite an impressive theoretical and experimental effort, no hints of new physics at such scale has been found in experiments. Dark sectors provide an interesting alternative to TeV scale extensions of the SM to explain the open questions in particle and astroparticle physics. Going beyond minimal models, rich dark sectors extend the SM to a complex theory with multiple particles and interactions, in analogy to the SM itself. They have a wealth of theoretical and astrophysical/cosmological consequences and can lead to phenomenological signatures that can be markedly different to that of minimal ones. These include short-lived particles and semi-visible decay signatures, as opposed to minimal models where new states are typically long-lived and purely visible or invisible resonances. Given the experimental configurations and analysis strategies, current dark sector searches might miss such signatures. We advocate a dedicated programme of searches for rich dark sectors that overcomes the assumptions on minimality and on the long lifetime of particles and encompasses a broader range of possibilities. Here, we discuss a prototype model that includes a complex structure akin to the SM: multiple generations of fermions charged under a new spontaneously-broken gauge symmetry.

   hep-phhep-exNPB(2025)·4 citations
6. 06*

   Synthetic Training and Representation Bridging in Reconstruction Domains

   Wonyong Chung🇺🇸

   Reconstructing low-dimensional truth labels from high-dimensional experimental data is a central challenge in any scenario that relies on robust mappings across this so-called domain gap, from multi-particle final states in high-energy physics to large-scale early-universe structure in cosmological surveys. We introduce a new method to bridge this domain gap with an intermediate, synthetic representation of truth that differs from methods operating purely in latent space, such as normalizing flows or invertible approaches, in that the synthetic data is specifically engineered to represent intrinsic detector hardware capabilities of the system at hand. The hypothesis is that by encoding physical properties of the detector response available only in full simulation, such synthetic representations result in a less lossy compression and recovery than a direct mapping from truth to experimental data. We demonstrate a first implementation of this concept with full simulation of a dual-readout crystal electromagnetic calorimeter for future collider detectors, in which the synthetic data is constructed to be the simulated detector hits corresponding to photon tracks of scintillation and Cerenkov photons. We refer to these signals as simulated observables as they would not be physical observables in a real detector, but are nonetheless representations of a real physical process. First results show that the synthetic representation naturally anchors the neural network architecture to a known physical method, in this case the dual-readout correction. We believe this strategy opens new avenues for machinistic interpretability and explainability of ML-based reconstruction methods. In the case of anomalous signal detection, we hypothesize that anomalous signals detected in networks trained on synthetic data rooted in a physical process are more likely to be indicative of a genuinely physical anomaly.

   hep-phhep-ex0 citations
7. 07*

   Vacuum pair production under spatially asymmetric time-oscillating electric fields

   Mamat Ali Bake🇨🇳 · Obulkasim Olugh🇨🇳

   We investigate electron-positron pair production from the quantum vacuum in spatially asymmetric, time-oscillating electric fields using the Dirac-Heisenberg-Wigner (DHW) formalism. The field configuration combines spatially separated Sauter-type pulses with temporal oscillations, including frequency chirps and phase modulation. Our results demonstrate that spatial asymmetry significantly enhances pair production compared to symmetric fields, while optimal tuning of temporal parameters (e.g., frequency $\omega$ and chirp $b$) further amplifies the yield. For $\omega \gtrsim 0.4m$, multiphoton-dominated processes generate oscillatory momentum spectra, whereas low-frequency fields ($\omega \lesssim 0.3m$) exhibit tunneling-dominated Gaussian distributions. Chirped fields induce spectral asymmetry and interference patterns, with peak yields increasing by up to a factor of 9 for $\omega =0.7m$ and $b=0.5\omega /\tau$. These findings provide a pathway to optimize pair production in experimentally feasible spatiotemporal field configurations.

   hep-phPRD(2025)·5 citations
8. 08*

   Calculation of the axial-vector coupling constant $g_A$ to two loops in covariant chiral perturbation theory

   Véronique Bernard🇫🇷 · Jambul Gegelia🇩🇪 · Shayan Ghosh🇩🇪 · Ulf-G. Meißner🇩🇪

   We present a calculation of the leading two-loop corrections to the axial-vector coupling constant $g_A$ in two covariant versions of two-flavor baryon chiral perturbation theory. Taking the low-energy constants from a combined analysis of elastic and inelastic pion-nucleon scattering, we find that these corrections are rather moderate.

   hep-phhep-latnucl-exnucl-thPLB(2025)·6 citations
9. 09*

   The light meson decays of $D$ wave charmonia

   Xiao-Yu Qi🇨🇳 · Xing-Dao Guo🇨🇳 · Dian-Yong Chen🇨🇳

   Motivated by the large non-$D\bar{D}$ branching fraction of $\psi (3770)$, we investigate the light meson decays of the $D$-wave charmonia in the present work with the meson loop mechanism. With the parameter range determined by $\psi (3770)\to \varphi \eta$, our estimations of the branching fractions of the light meson decays of $\psi (3770)$ are consistent with the estimations in the literature. As for $\psi (3823)$, the partial widths of $K^{\ast }{\bar{K}}^{\ast }$ channel is estimated to be around 200 keV, which is the the predominant light meson decay channel of $\psi (3823)$. Our estimations also indicate that $K^{(\ast )}{\bar{K}}^{(\ast )}$ and $\rho \pi$ are the dominant light meson decay modes of $\psi (3842)$, while ${\eta }_{c2}$ dominantly decays into $\rho \rho$, $K^{\ast }{\bar{K}}^{\ast }$, $\omega \omega$ and $\varphi \varphi$.

   hep-phPRD(2025)·2 citations
10. 10*

    Beam single spin asymmetry $A_{LU}^{\sin {\varphi }_R}$ of the dihadron production in SIDIS process

    Yanli Li🇨🇳 · Keyang She🇨🇳 · Hui Li🇨🇳 · Xiaoyu Wang🇨🇳 · De-Min Li🇨🇳 · Zhun Lu🇨🇳

    We study the longitudinal beam single-spin asymmetry $A_{LU}^{\sin {\varphi }_R}$ of dihadron production in semi-inclusive deep inelastic scattering process with a polarized electron beam scattering off an unpolarized proton target. The asymmetry arises from the convolutions of twist-3 PDF $e(x)$ and twist-2 DiFF $H_1^{\sphericalangle }$ as well as twist-2 PDF $f_1(x)$ and twist-3 DiFF ${\tilde{G}}^{\sphericalangle }$. Using the spectator model calculations for the twist-3 PDF $e(x)$, the DiFFs $D_1,H_1^{\sphericalangle }$, and ${\tilde{G}}^{\sphericalangle }$, we estimate the BSA $A_{LU}^{\sin {\varphi }_R}$ at the kinematical configuration of CLAS and CLAS12. We find good agreement with $z$- and $M_h$-dependencies data, though $x$- and $Q^2$- dependencies show discrepancies. We include DGLAP evolution of $e(x)$ and provide predictions for COMPASS, EIC, and EicC. The negligible contribution from $f_1(x)\otimes {\tilde{G}}^{\sphericalangle }$ supports the Wandzura-Wilczek approximation, while our results highlight the importance of QCD evolution in twist-3 PDF analyses.

    hep-phPRD(2025)·3 citations
11. 11*

    Mass spectrum of heavy tetraquarks in variational approach

    A. V. Eskin🇷🇺 · A. P. Martynenko🇷🇺 · F. A. Martynenko🇷🇺

    Within the framework of the quark model and the variational method, the bound states of four heavy quarks (tetraquarks) are investigated. The basis variational wave functions are chosen in the Gaussian form. The matrix elements of the Hamiltonian are calculated analytically. Numerical calculation of the energy levels of tetraquarks is performed using a program in the Matlab system. Hyperfine structure of the spectrum is calculated. To increase the accuracy of the calculation, relativistic corrections are taken into account.

    hep-phPhys.Atom.Nucl.(2025)·4 citations
12. 12*

    Scattering Entanglement Entropy and Its Implications for Electroweak Phase Transitions

    Jia Liu🇨🇳 · Masanori Tanaka🇨🇳 · Xiao-Ping Wang🇨🇳 · Jing-Jun Zhang🇨🇳 · Zifan Zheng🇨🇳

    We investigate the connection between the entanglement entropy in scattering processes and the dynamics of electroweak phase transitions. Recent work has shown that the scattering entanglement entropy can provide new insight into Standard Model parameters. In this study, we propose that the maximum of the entanglement entropy in scattering amplitudes may serve as a diagnostic for first-order electroweak phase transitions in the early universe. We analyze a simplified extension of the Standard Model consisting of the Higgs boson $h$ coupled to $O(N)$ real singlet scalars $S$ via the Higgs portal coupling ${\lambda }_{hS}$. By explicitly calculating the maximum entanglement entropy, we demonstrate that it grows with increasing ${\lambda }_{hS}$, and that both first-order and strong first-order electroweak phase transitions are favored in regions of parameter space with large maximum entropy. Our results suggest that entanglement-based observables may encode meaningful information about the underlying dynamics of electroweak symmetry breaking and provide a novel perspective on phase transition phenomena.

    hep-phhep-thPRD(2025)·16 citations
13. 13*

    pNGB Higgs Naturalness at a Tipping Point

    Matthew McCullough🇨🇭 · Adriana Menkara🇩🇪 · Ennio Salvioni🇬🇧

    In scenarios where the Higgs is viewed as a pseudo Nambu-Goldstone boson (pNGB) the question of naturalness finds itself, from a phenomenological perspective, at a tipping point between direct searches and precision. If, by the end of the High-Luminosity LHC operation, all experimental results were to remain consistent with the Standard Model, precision Higgs coupling measurements will begin to drive the naturalness tension. To illustrate this from a fresh perspective we construct a maximally natural `Kitchen Sink' model, throwing into the mix three approaches to symmetry-based naturalness: Supersymmetry, Twin Higgs, and pNGB Higgs models with a Gegenbauer potential. In other words, we build a `Supersymmetric Gegenbauer's Twin' model. This model not only maximises naturalness, at least from a technical perspective, but can also interpolate between all three ingredients smoothly, revealing the interplay between direct exploration and precision. Implications for FCC-ee and FCC-hh are discussed.

    hep-phhep-exPRD(2025)·2 citations
14. 14*

    How to tame penguins: Advancing to high-precision measurements of ${\varphi }_d$ and ${\varphi }_s$

    Kristof De Bruyn🇳🇱 · Robert Fleischer🇳🇱 · Eleftheria Malami🇩🇪

    The complex phases ${\varphi }_d$ and ${\varphi }_s$, associated with the mixing between neutral $B_q^0$ and ${\bar{B}}_q^0$ mesons ($q\in \{d,s\}$), are key observables to test the Standard Model and search for contributions from new physics. They are conventionally determined from the measurements of mixing-induced CP violation in the decays $B_d^0\to J/\psi K^0$, $B_s^0\to J/\psi \varphi$ and $B_s^0\to D_s^{+}{D}_s^{-}$. To reach the highest possible precision on ${\varphi }_d$ and ${\varphi }_s$, it is crucial that corrections from next-to-leading order effects - primarily associated with penguin decay topologies - are accounted for. The strategy adopted in this paper uses the $SU(3)$ flavour symmetry of QCD to relate the unknown contributions from penguin topologies to their counterparts in suitably-chosen control modes, where their effects are enhanced. Utilising new CP asymmetry measurements from LHCb on the decays $B_s^0\to D_s^{+}{D}_s^{-}$, $B_d^0\to D^{+}{D}^{-}$, $B^{+}\to J/\psi K^{+}$ and $B^{+}\to J/\psi {\pi }^{+}$, as well as from Belle-II on the decay $B_d^0\to J/\psi {\pi }^0$, we present the current state-of-the-art picture on controlling the penguin contributions and extract ${\varphi }_d$ and ${\varphi }_s$ from the corresponding observables. We explore the prospects for the end of the Belle-II and HL-LHC flavour physics programmes, and demonstrate the importance of measuring the control modes with future data.

    hep-phEPJC(2026)·9 citations
15. 15*

    Chiral interactions, chiral states and "chiral neutrino oscillations"

    A. Yu. Smirnov🇩🇪

    In vacuum the ``chiral neutrino oscillations'', i.e. the periodic transitions between the left- and right-handed states do not occur. The produced state differs from the chiral component that appear in the Lagrangian of interactions and should be computed for each specific process. The phase difference between components of a produced neutrino is space-time independent. This neutrino state consists of only positive energy solutions of the Dirac equation and therefore the energy splitting $2E_{\nu }$ between the components with different helicities that would drive the chiral oscillations does not exist. Consideration in terms of neutrino propagators leads to the same conclusion. The situation is similar for the Majorana neutrinos and in the presence of flavor mixing. However, oscillations of the neutrino states produced in the chiral interactions are possible in matter with the length determined by the matter potential. Description of oscillations in terms of amplitudes of production and detection is elaborated that does not lead to any misconception. In the expanding Universe the relic neutrinos adiabatically convert to equal number densities of the left and right handed components.

    hep-phNPB(2025)·6 citations
16. 16*

    Constraints to Lorentz violation and ultrahigh-energy electrons in D-foamy space-times

    Chengyi Li🇨🇳 · Bo-Qiang Ma🇨🇳

    We entertain the constraints that the absence of vacuum Cherenkov radiation of ultrahigh-energy electrons inferred from LHAASO observations of the Crab Nebula can impose on generic models in which Lorentz symmetry of the particle vacuum is violated, as established by some recent studies in \href{https://doi.org/10.1016/j.physletb.2022.137034}{\emph{Phys. Lett. B} {\bf 829} (2022) 137034}; \href{https://doi.org/10.1016/j.physletb.2022.137536}{{\bf 835} (2022) 137536}; \href{https://doi.org/10.1103/PhysRevD.108.063006}{\emph{Phys. Rev. D} {\bf108} (2023) 063006}. We demonstrate in the present paper, that implementing a phenomenological approach to the Lorentz violation, the rates of this vacuum process are substantial such that one is justified in deriving bounds on the violation scales from simple threshold analysis just as these works did. Albeit such results are likely effective then, they do not apply in the same form among scenarios. Specifically, we show that these Cherenkov constraints are naturally evaded in models of space-time foam inspired from~(supercritical) string theory, involving D-branes as space-time defects in a brane-world scenario, in which subluminous energy-dependent refractive indices of light have been suggested. We examine here two specific foam situations and find for both cases~(though, for different reasons) the potentiality that charged quanta such as electrons do \emph{not} radiate as they pass through the gravitational vacuum `medium' despite moving faster than photons.

    hep-phastro-ph.HEgr-qchep-thJHEP(2025)·3 citations
17. 17*

    Mechanical form factors and densities of non-relativistic fermions

    Adam Freese🇺🇸

    The hadron physics community has been actively debating the interpretation of so-called mechanical properties of hadrons. Non-relativistic quantum-mechanical systems like the hydrogen atom have been appealed to in these debates as analogies. Since such appeals are likely to continue, it is important to have Galilei-covariant expressions for matrix elements of the energy-momentum tensor. In this work, I obtain Galilei-covariant breakdowns of such matrix elements into mechanical form factors, with a special focus on spin-half states. I additionally study the spatial densities associated with these form factors, using the pilot wave interpretation to guide their breakdown into contributions from internal structure and from quantum-mechanical effects such as wave packet dispersion. For completeness, I also obtain non-relativistic Breit frame densities.

    hep-phnucl-thquant-phPRD(2025)·9 citations
18. 18*

    Revisiting the connection of baryon number, lepton number, and operator dimension

    Julian Heeck🇺🇸 · Diana Sokhashvili🇺🇸

    The effects of heavy new particles beyond the Standard Model can be conveniently captured through higher-dimensional effective operators. As noted long ago by Weinberg, the amount of baryon and lepton number an operator can carry is intricately connected to its mass dimension. We derive an improved inequality for this connection and compare it to explicit operator constructions up to mass dimension 25. For the effective field theory of Standard Model plus right-handed neutrinos, our relationship is even an equality up to high mass dimension.

    hep-phPLB(2025)·5 citations
19. 19*

    An Effective Theory for Higgs Inflation

    A. Tronconi🇮🇹 · G. Venturi🇮🇹

    The generation of large curvature perturbations associated with the production of primordial black holes is studied in the context of a Higgs inflaton. To enable this amplification, we consider an inflationary model in which the tree-level action for gravity and the Standard Model Higgs is modified by quantum corrections, described by a series of higher-dimension operators. Finally within a minimal EFT framework, we present two viable models in which the spectrum of curvature perturbations generated by the Higgs field is consistent with CMB observations and can lead to the formation of primordial black holes in the asteroid mass range, potentially accounting for the entirety of dark matter.

    hep-phastro-ph.COgr-qchep-thJCAP(2025)·1 citation
20. 20*

    Local Baryon Number at the LHC

    Jon Butterworth🇬🇧 · Hridoy Debnath🇺🇸 · Joseph Egan🇬🇧 · Pavel Fileviez Perez🇺🇸

    The minimal theory in which baryon number is spontaneously broken at the low scale predicts new fermions, one of which is a dark matter candidate, from gauge anomaly cancellation. We discuss the production mechanisms and decays of these new fermions, which include channels with multi-leptons, and channels with long-lived charged fermions that can give rise to exotic signatures with 'kinked' tracks at the Large Hadron Collider. We evaluate the contraints on the theory from current LHC searches and measurements, and briefly comment on the excess in top pair production at threshold recently reported by CMS. We also discuss predictions for the $h\to \gamma Z_B$ decay, where $h$ is the SM-like Higgs and $Z_B$ is the new gauge boson associated with baryon number.

    hep-phhep-exhep-thPRD(2025)·6 citations
21. 21*

    Beyond the Standard Model contributions to dipole moments

    Nicola Valori🇪🇸 · Oscar Vives🇪🇸

    The goal of this work is to provide a pedagogical introduction to dipole moments and dipole transitions in theories beyond the Standard Model, with a focus on the lepton sector. We emphasize the exceptional sensitivity of dipole observables to new physics, analyzing the most sensitive processes, such as the muon anomalous magnetic moment, the electric dipole moment of the electron, and the branching ratio $\text{BR}(\mu \to e\gamma )$. This review is intended for PhD students, early-career researchers, and anyone entering the field for the first time. It does not aim to provide a complete overview of all models in the literature, but rather to serve as an accessible guide, using simple and representative examples from the most well-studied extensions of the Standard Model.

    hep-ph8 citations
22. 22*

    Measurement of medium-induced acoplanarity in central Au-Au and pp collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV using direct-photon+jet and ${\pi }^0$+jet correlations

    The STAR Collaboration

    The STAR Collaboration reports measurements of acoplanarity using semi--inclusive distributions of charged--particle jets recoiling from direct photon and ${\pi }^0$ triggers, in central Au+Au and $pp$ collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. Significant medium--induced acoplanarity broadening is observed for large but not small recoil jet resolution parameter, corresponding to recoil jet yield enhancement up to a factor of $\approx 20$ for trigger--recoil azimuthal separation far from $\pi$. This phenomenology is indicative of the response of the Quark--Gluon Plasma to excitation, but not the scattering of jets off of its quasiparticles. The measurements are not well--described by current theoretical models which incorporate jet quenching.

    ↳ nucl-exhep-exhep-phnucl-thPRC(2026)·6 citations
23. 23*

    Spectroscopic Supermassive Dark Star candidates

    Cosmin Ilie🇺🇸 · Sayed Shafaat Mahmud🇺🇸 · Jillian Paulin · Katherine Freese🇺🇸

    Dark Stars, i.e. early stars composed almost entirely of hydrogen and helium but powered by Dark Matter, could form in zero metallicity clouds located close to the center of high redshift Dark Matter halos. In 2023 three of us identified (in a PNAS work) the first three photometric Dark Star candidates: JADES-GS-z11-0, JADES-GS-z12-0, and JADES-GS-z13-0. We report here our results of a followup analysis based on available NIRSpec JWST data. We find that JADES-GS-z11-0 and JADES-GS-z-13-0 are spectroscopically consistent with a Dark Star interpretation. Moreover, we find two additional spectroscopic Dark Star candidates: JADES-GS-z14-0 and JADES-GS-z-14-1, with the former being the most distant luminous object ever observed. We furthermore identify a feature in its spectrum indicative of the smoking gun signature of Dark Stars: the He II$\lambda$1640 absorption line. In view ALMA's recent identification of a probable OIII nebular emission line in the spectrum of JADES-GS-z14-0, the simple interpretation of this object as an isolated Dark Star is unlikely. If both spectral features survive follow-up observations it would imply a Dark Star embedded in a metal rich environment, requiring theoretical refinements of the formation of evolution of Dark Stars, which in previous studies were assumed to form in isolation, without any companions.

    ↳ astro-ph.COhep-phProc.Nat.Acad.Sci.(2025)·8 citations
24. 24*

    Revealing the nature of long-period transients with space-based gravitational-wave interferometers

    Arthur G. Suvorov🇪🇸 · Clara Dehman🇪🇸 · José A. Pons🇪🇸

    A few members of the recently discovered class of long-period transients have been identified as binaries with white-dwarf primaries. In most cases, however, electromagnetic data are inconclusive, and isolated magnetars or compact binaries remain viable. If the pulsation period matches that of the orbit -- as is the case for ILT J1101+5521 and GLEAM-X J0704--37 -- some of these elusive radio transients could be gravitational-wave bright in the mHz band. Space-based interferometers could thus be used to provide independent constraints on their nature. We quantify the signal-to-noise ratio for the known systems under various scenarios and show that a few could be detectable for sufficiently large chirp masses. Astrophysical implications for (non)detections are discussed.

    ↳ astro-ph.HEgr-qchep-phApJ(2025)·7 citations
25. 25*

    Magnetar field dynamics shaped by chiral anomalies and helicity

    Clara Dehman🇪🇸 · José A. Pons🇪🇸

    The chiral magnetic effect (CME) -- a macroscopic manifestation of the quantum chiral anomaly -- induces currents along magnetic field lines, facilitating mutual conversion between chiral asymmetry and magnetic helicity. Although the finite electron mass suppresses chiral asymmetry through spin-flip processes, we demonstrate that the CME effectively shapes magnetar field evolution. Magnetic helicity acts as a persistent internal source of chiral asymmetry, which mediates the redistribution of magnetic energy across spatial scales, without requiring an external energy source. Our three-dimensional magneto-thermal simulations of the neutron star crust reveal a novel mechanism that significantly reconfigures the magnetic field inherited at birth, amplifying both toroidal and poloidal large-scale dipolar components (crucial for spin-down) to strengths of >1e14 G within just a century, at the expense of small-scale structures. This astrophysical application of the CME, distinct and complementary to conventional hydrodynamic dynamo models, offers an innovative framework for understanding magnetar field dynamics and provides a transformative solution to the origin of their exceptionally strong, large-scale fields.

    ↳ astro-ph.HEhep-phhep-thPRResearch(2025)·10 citations
26. 26*

    Study of the Quartic Anharmonic Oscillator Using the System's Wave Function Expansion in the Oscillator Basis

    V. A. Babenko · A. V. Nesterov

    The quantum quartic anharmonic oscillator with the Hamiltonian $H=\frac{1}{2}\left(p^2+x^2\right)+\lambda x^4$ is a classical and fundamental model that plays a key role in various branches of physics, including quantum mechanics, quantum field theory, high-energy particle physics, and other areas. To study this model, we apply a method based on a convergent expansion of the system's wave function in a complete set of harmonic oscillator eigenfunctions -- namely, the basis of eigenfunctions ${\phi }_n^{(0)}$ of the unperturbed Hamiltonian $H^{(0)}=\frac{1}{2}\left(p^2+x^2\right)$. This approach enables a thorough analysis and calculation of the oscillator's physical characteristics. We demonstrate very good convergence of all calculated quantities with respect to the number of basis functions included in the expansion, over a wide range of $\lambda$ values. We have computed the energies of the ground and the first six excited states for a broad range of the coupling constant $\lambda$, and also calculated and constructed the corresponding wave functions. Additionally, we propose and detail an improved version of the expansion method using a modified optimized oscillator basis with variable frequency. This modification significantly accelerates the convergence of expansions across the entire range of $\lambda$, thereby greatly enhancing the efficiency of the method and allowing accurate calculations with a very small number of expansion functions $N\lesssim 10$. As a result, this modified approach provides an essentially complete, simple, and efficient solution to the problem of the anharmonic oscillator, enabling straightforward computation of all its physical properties -- including the energies and wave functions of both ground and excited states -- for arbitrary values of $\lambda$.

    ↳ quant-phhep-phInt.J.Mod.Phys.A(2025)·2 citations
27. 27*

    Towards holographic color superconductivity in QCD

    Jesús Cruz Rojas🇲🇽 · Tuna Demircik🇵🇱 · Christian Ecker🇩🇪 · Matti Järvinen🇰🇷

    We extend the holographic V-QCD model by introducing a charged scalar field sector to represent the condensation of paired quark matter in the deconfined phase. By incorporating this new sector into the previously established framework for nuclear and quark matter, we obtain a phase diagram that, in addition to the first-order deconfinement transition and its critical end-point, also features a second-order transition between paired and unpaired quark matter. The critical temperature for quark pairing exhibits only a mild dependence on the chemical potential and can reach values as high as $T_{\mathrm{crit}}\approx 30\mathrm{MeV}$. Comparison of the growth rate for the formation of homogeneous paired phases to the growth rate of previously discovered modulated phases suggests that the former is subdominant to the latter.

    ↳ hep-thastro-ph.HEhep-phSciPost Phys.(2026)·6 citations
28. 28*

    Scalable Quantum State Preparation via Large-Language-Model-Driven Discovery

    Qing-Hong Cao🇨🇳 · Zong-Yue Hou🇨🇳 · Ying-Ying Li🇨🇳 · Xiaohui Liu🇨🇳 · Zhuo-Yang Song🇨🇳 · Liang-Qi Zhang🇨🇳 · Shutao Zhang🇨🇳 · Ke Zhao🇨🇳

    Efficient quantum state preparation remains a central challenge in first-principles quantum simulations of dynamics in quantum field theories, where the Hilbert space is intrinsically infinite-dimensional. Here, we introduce a large language model (LLM)-assisted framework for quantum-circuit design that systematically scales state-preparation circuits to large lattice volumes. Applied to a 1+1d XY spin chain, the LLM autonomously discovers a compact 4-parameter circuit that captures boundary-induced symmetry breaking with sub-percent energy deviation, enabling successful validation on the \texttt{Zuchongzhi} quantum processor. Guided by this insight, we extend the framework to 2+1d quantum field theories, where scalable variational ansätze have remained elusive. For a scalar field theory, the search yields a symmetry-preserving, 3-parameter shallow-depth ansatz whose optimized parameters converge to size-independent constants for lattices $n\ge 4$, providing, to our knowledge, the first scalable ansatz for this class of 2+1d models. Our results establish a practical route toward AI-assisted, human-guided discovery in quantum simulation.

    ↳ quant-phcs.AIhep-lathep-ph6 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.