Wed·Apr 16, 2025Wednesday·April 16, 2025

1. 01*

   Neutrino oscillations and scattering theory

   Ilian Dobrev🇩🇪 · Kirill Melnikov🇩🇪 · Thomas Schwetz🇩🇪

   We derive the neutrino oscillation probability in vacuum using scattering theory methods developed earlier in the context of collider physics. It is computed from Feynman diagrams that combine neutrino production and detection processes into a single quantum amplitude. Initial-state particles in the neutrino source and the detector are treated as wave packets. In contrast to many other approaches, we work with transition probabilities, rather than the amplitude itself, and do not specify the form of the wave packets to arrive at the neutrino oscillation formula. Our approach offers a simple and transparent framework to discuss decoherence effects in neutrino oscillations, as well as the effects of the finite lifetime of the neutrino source. The latter are particularly relevant for oscillation experiments using neutrinos from pion decays in flight.

   hep-phJHEP(2025)·3 citations
2. 02*

   Energy-Enhanced Expansion of the Standard Model Effective Field Theory

   Benoît Assi🇺🇸 · Adam Martin🇺🇸

   We formalize energy-scaling arguments in the Standard Model Effective Field Theory (SMEFT) to estimate effects of operators up to dimension ten. Introducing a classification based on the number of external legs and an energy-counting parameter, we establish a dual expansion in \(v/\Lambda\) and \(E/\Lambda\). Extending to four-, five-, and six-particle vertices, our framework highlights energy-enhanced operators that dominate high-energy processes at the HL-LHC. This organization streamlines experimental analyses to only include operators with energetic impact in their analyses and enhances the discoverability of new physics within the SMEFT framework.

   hep-phhep-exPRD(2025)·6 citations
3. 03*

   Mass spectrum and magnetic moments of singly-charmed baryons: a quark-diquark model analysis of ${\Omega }_c(3185{)}^0$ and ${\Omega }_c(3327{)}^0$

   Sinem Küçükyılmaz🇹🇷 · Halil Mutuk🇹🇷

   Research on singly-heavy baryons, especially those with a charm quark, offers a distinct perspective on the non-perturbative behavior of Quantum Chromodynamics (QCD). In this work, we investigate the recently observed ${\Omega }_c(3185{)}^0$ and ${\Omega }_c(3327{)}^0$ as singly-charmed baryons within the framework of the quark-diquark model. By employing a non-relativistic method with a Cornell-like potential, we systematically determine magnetic moments and mass spectra. Our analysis reveals that the ${\Omega }_c(3185{)}^0$ can be effectively described as a $2S$ state with quantum numbers $J^P={\frac{1}{2}}^{+}$ or ${\frac{3}{2}}^{+}$, or alternatively as a $1P$ state with $J^P={\frac{1}{2}}^{-}$ or ${\frac{3}{2}}^{-}$, depending on the diquark configuration. Similarly, the ${\Omega }_c(3327{)}^0$ is consistent with a $2S$ configuration. We also investigate their magnetic moments, emphasizing the critical role of diquark correlations in shaping the electromagnetic properties of these states. Our results not only validate existing theoretical models but also offer new insights into the nature of singly-heavy baryons, setting the stage for future experimental and theoretical investigations in heavy baryon spectroscopy. This paper emphasizes the importance of diquark configurations in elucidating the mass spectrum and electromagnetic characteristics of singly-charmed baryons, aiding in the broader effort to decipher QCD intricacies.

   hep-phhep-exhep-latPLB(2025)·3 citations
4. 04*

   Analyzing the general conditions for modulus stabilization in a warped braneworld

   Soham Bhattacharyya🇮🇳 · Soumitra SenGupta🇮🇳

   In braneworld scenarios with compact extra dimensions, the modulus field typically remains undetermined without an appropriate stabilization mechanism. A common approach introduces a bulk scalar field that generates an effective potential for the modulus with a stable minimum. In this work, we explore some novel aspects of such stabilization mechanisms. We study how the bulk scalar profile influences the stabilization procedure. Following the approach of Chacko et al. [1], we analyze several representative cases using methods of singular perturbation theory. We identify a consistent relationship between the structure of the bulk potential and the emergence of a stabilized modulus, and outline the general conditions that any bulk potential must satisfy to enable stabilization. In this context, we also examine a potential connection between geometric consistency conditions - specifically, the "brane world sum rules" - and the stabilized value of the modulus. In some scenarios where stabilization occurs, we find that these sum rules can offer additional constraints on the modulus, providing a complementary perspective on its determination. Taken together, these results offer a broader perspective on the mechanisms that govern modulus stabilization in higher-dimensional warped geometries.

   hep-phgr-qchep-thEPJC(2025)·3 citations
5. 05*

   Strongly electroweak phase transition with $U(1{)}_{L_{\mu }-L_{\tau }}$ gauged non-zero hypercharge triplet

   Shilpa Jangid🇰🇷 · Anirban Biswas🇮🇳 · Seong Chan Park🇰🇷

   This article considers three non-zero hypercharge triplets as an extension of the Standard Model Higgs doublet. Under extra $U(1{)}_{L_{\mu }-L_{\tau }}$ symmetry, the triplets are charged. We examine the stability of the electroweak vacuum at the two-loop and tree-levels. The two-loop $\beta$-functions are found to be capable of satisfying the vacuum stability up to the Planck scale. On the other hand, only up to $10^{12}$ GeV can the perturbative unitarity be satisfied because of the increase in the positive influence from triplet degrees of freedom. For the strongly electroweak first-order phase transition, the parameter space permitted by the Planck scale stability is examined. Because the triplet degrees of freedom contribute sufficiently to the cubic term, the model satisfies the strongly first order phase transition for the triplet bare mass parameters up to the TeV scale. For all mass ranges, it is found that this model predicts a strongly first-order phase transition until the degrees of freedom are heavy enough to separate from the thermal bath. The gravitational wave signatures are tested at the benchmark places that fulfill the strongly first-order phase transition. The measurable frequency range of the LISA and BBO experiments also turns out to contain the benchmark points permitted by Planck scale stability, strongly first-order phase transition.

   hep-phPTEP(2026)·2 citations
6. 06*

   $CP$-violation and $U$-spin symmetry in four-body bottom baryon decays

   Shibasis Roy🇮🇳

   In view of the recent observation of $CP$-violation in bottom baryon decays, we explore $CP$-asymmetry relations in charmless four-body decays of bottom baryons featuring fully charged hadronic final states. Starting with a general effective Hamiltonian, we derive amplitude relations among various decay modes within the framework of $U$-spin symmetry. These relations lead to symmetry-based predictions for $CP$-violating rate asymmetries in $U$-spin conjugate decay channels. Furthermore, we demonstrate that all leading-order amplitude relations are violated once $U$-spin breaking effects are taken into account.

   hep-phhep-exPLB(2025)·4 citations
7. 07*

   Exploring the nature of ${\eta }_1(1855)$ and it's partner in a chiral quark model

   Yue Tan🇨🇳 · Yu-Heng Wu🇨🇳 · Qi Huang🇨🇳 · Xiaoyun Chen🇨🇳 · Xiaohuang Hu🇨🇳 · Youchang Yang🇨🇳 · Jialun Ping🇨🇳

   Inspired by the recent experimental discoveries of \(X(3872)\) (\(c\bar{q}\)-\(q\bar{c}\)) and \(T_{cc}\) (\(c\bar{q}\)-\(c\bar{q}\)), we systematically study two four-quark systems: the \(K K_1\) (\(q\bar{s}\)-\(q\bar{s}\)) system and the \(K \bar{K}_1\) (\(q\bar{s}\)-\(s\bar{q}\)) system, which is a candidate for the recently observed \(\eta_1(1855)\). Within the framework of an accurate few-body calculation method (GEM), we employ the chiral quark model to simultaneously consider the molecular and diquark structures of these two multiquark systems and include their channel coupling effects. Our results show that the \(K \bar{K}_1\) system remains a scattering state. On the other hand, due to the presence of a good-diquark structure in the \(K K_1\) system, we obtain a bound state in the coupled-channel calculation. The primary contribution to the binding energy comes from the exchange of \(\pi\)-meson and \(\sigma\)-meson. The inter-quark distance indicates that it is a compact four-quark structure.

   hep-phPRD(2025)·2 citations
8. 08*

   Dark Matter and Electroweak Phase Transition in the $Z_2$ Symmetric Georgi-Machacek Model

   Chih-Ting Lu🇨🇳 · Yongcheng Wu🇨🇳 · Siyu Xu🇨🇳

   We present a comprehensive investigation of the $Z_2$ symmetric Georgi-Machacek (GM) model, focusing on the dark matter (DM) in the model and the electroweak phase transition (EWPT). Our analysis encompasses multiple detections for the DM candidates, including collider searches at the LHC and LEP, the direct detection and indirect detection. Furthermore, we also explore the possibility of a first-order EWPT in this framework. The gravitational wave (GW) generated from the first-order EWPT also provides a detection method for the parameter space in the $Z_2$ symmetric GM model providing viable DM candidate. It is found that the current DM searches, especially the direct detection, provide strong constraints on the parameter space, while the GW signal can be complementary around the Higgs resonant region.

   hep-phJHEP(2025)·7 citations
9. 09*

   Investigating the light curve variation of magnetic white dwarfs induced by the axion-photon conversion

   Hao-Chen Tian🇨🇳 · Zhao-Yang Wang🇨🇳 · Yun-Feng Liang🇨🇳 · Zhao-Wei Du🇨🇳

   Axion-photon oscillation refers to the process of mutual conversion between photons and axions when they propagate in a magnetic field. This process depends on the strength of the background magnetic field, and magnetic white dwarfs provide a natural laboratory for testing this process. In this work, we study the behavior of axion-photon oscillation near magnetic white dwarfs: as the magnetic white dwarf rotates, its magnetic field structure rotates accordingly, causing a periodic change of the magnetic field along the path of photons. These variations affect the axion-photon oscillation process experienced by the photons emitted from the white dwarf, thereby inducing a periodic modulation in the intensity and polarization of the white dwarf's thermal emission that we observe. Our study focuses on the impact of axion effects on the observed light curve variation and conducts a detailed investigation through numerical calculations. Using the light curve data of the white dwarf PG1015+014 obtained from the observations by the Jacobus Kapteyn Telescope, which has a photometric precision of $\sim 1\%$, we derive the constraints on axion parameters. In the axion mass range of $\lesssim 10^{-8}\mathrm{eV}$, the 95\% credible interval upper limit of the axion-photon coupling $g_{a\gamma \gamma }$ is constrained to $<8.1\times 10^{-12}\mathrm{Ge}{\mathrm{V}}^{-1}$.

   hep-phastro-ph.HEPRD(2025)·3 citations
10. 10*

    Origin of Reactor Antineutrino Anomaly

    L.M. Slad🇷🇺

    The reactor antineutrino anomaly, discovered in 2011, means a noticeable difference between the observed rate of inverse beta decays and the expected (theoretical) rate of such processes based on the measurement of the spectra of electrons in beta decay of ${}^{235}$U, ${}^{239}$Pu, ${}^{241}$Pu, and ${}^{238}$U nuclei and their subsequent conversion into right-handed antineutrino spectra. This paper provides a rationale for the fact that both right-handed and left-handed antineutrinos are produced in beta decays of nuclei. But the conversion procedure in any case assigns a right-handed antineutrino to each electron, which leads to the superiority of the theoretical rate of inverse beta decays over the experimental one. The right-handed antineutrino is produced in the mode of beta decay of the nucleus due to the standard electroweak interaction. The left-handed antineutrino appears in the mode caused by the existence of a interaction, the carrier of which is a massless pseudoscalar boson having a Yukawa coupling with the electron neutrino and nucleons. The emission of such a boson from a virtual right-handed antineutrino converts it into a free left-handed antineutrino.

    hep-phhep-exnucl-th0 citations
11. 11*

    $B$ meson decays to vector charmonium(like) states and a $K$ meson: the role of final-state interactions

    Qi-Wei Yuan🇨🇳 · Qi Wu🇨🇳 · Ming-Zhu Liu🇨🇳

    A series of vector charmonium(like) states, accompanied by a $K$ meson, have been observed in the decays of $B$ meson. These processes are color-suppressed at the quark level, as inferred from topological diagram analysis. In this work, we calculate the branching fractions of the decays $B\to \psi K$, where $\psi$ denotes the charmonium(like) states $\psi (1S)$, $\psi (2S)$, $\psi (4040)$, $\psi (3770)$, and $\psi (4160)$. Our analysis incorporates both short-distance (naive factorization approach) and long-distance (final-state interactions) contributions. Within reasonable parameters, our results align with experimental data except for the $\psi (4160)$, suggesting its possible exotic nature. Furthermore, we find that long-distance contributions dominate these decay processes, highlighting the crucial role of final-state interactions in the productions of charmonium(like) states in $B$ decays.

    hep-phPRD(2025)·4 citations
12. 12*

    The imprints of QCD cascades in hadron multiplicity distribution

    Maciej Rybczyński🇵🇱 · Zbigniew Włodarczyk🇵🇱

    The relation between parton and hadron multiplicity distributions is discussed. To obtain parton multiplicity distribution we propose decomposition of the multiplicity distributions of final state hadrons. Such procedure offers hope for experimental testing of physical probes of quantum complexity.

    hep-phPRD(2025)·3 citations
13. 13*

    $P$-wave single charmed baryons of the $SU(3)$ flavor ${\bar{3}}_{\mathbf{F}}$

    Xuan Luo🇨🇳 · Yi-Jie Wang🇨🇳 · Hua-Xing Chen🇨🇳

    We study the $P$-wave single charmed baryons of the $SU(3)$ flavor ${\bar{3}}_{\mathbf{F}}$ within the framework of heavy quark effective theory. We systematically calculate their strong and radiative decay properties using the light-cone sum rule method. Besides the ${\Lambda }_c(2595)$, ${\Lambda }_c(2625)$, ${\Xi }_c(2790)$, and ${\Xi }_c(2815)$, our results suggest the existence of two additional ${\Lambda }_c$ baryons and two additional ${\Xi }_c$ baryons. Their masses, mass splittings within the same multiplets, and decay properties are summarized in Table V for future experimental searches.

    hep-phhep-exPRD(2025)·7 citations
14. 14*

    Probing Lorentz Invariance Violation in Z Boson Mass Measurements at High-Energy Colliders

    Juansher Jejelava🇬🇪 · Zurab Kepuladze🇬🇪

    We propose a minimal extension to the Standard Model by introducing a Lorentz Invariance Violation (LIV) term into the Z boson's dispersion relation, expressed as $p_{\mu }{p}^{\mu }=M_Z^2+{\delta }_{LIV}(p_{\mu }{n}^{\mu }{)}^2$, where ${\delta }_{LIV}$ defines the violation scale and $n^{\mu }$ is a unit Lorentz vector specifying the direction. This modification alters the Z boson propagator and decay rate, impacting the Drell-Yan process cross-section at high-energy colliders. Observable effects are most pronounced near the resonance region at high rapidities ($|Y|>4$), potentially shifting the perceived Z boson mass and inducing sidereal-time modulations for spacelike and lightlike LIV due to Earth's rotation. We outline a targeted search strategy for ATLAS and CMS, achieving sensitivity to LIV signatures down to $|{\delta }_{LIV}|\approx 10^{-8}$ (or $10^{-9}$ optimistically), offering new insights into historical and future collider data. Our model predicts systematic shifts in weak boson masses at higher collision energies, relevant to past Tevatron and LHC discrepancies, though current data are now consistent.

    hep-phhep-exhep-thPRD(2026)·2 citations
15. 15*

    Domain wall evolution beyond quartic potentials: The Sine-Gordon and Christ-Lee potentials

    R. Heilemann🇵🇹 · M. C. Rosa🇵🇹 · J. R. C. C. C. Correia🇫🇮 · C. J. A. P. Martins🇵🇹

    Domain walls are the simplest type of topological defects formed at cosmological phase transitions, and one of the most constrained. Their studies typically assume a quartic double well potential, but this model is not fully representative of the range of known or plausible particle physics models. Here we study the cosmological evolution of domain walls in two other classes of potentials. The Sine-Gordon potential allows several types of walls, interpolating between different pairs of minima (which demands specific numerical algorithms to separately measure the relevant properties of each type). The Christ-Lee potential parametrically interpolates between sextic and quartic behavior. We use multiple sets of simulations in two and three spatial dimensions, for various cosmological epochs and under various choices of initial conditions, to discuss the scaling properties of these networks. In the Sine-Gordon case, we identify and quantify deviations from the usual scaling behavior. In the Christ-Lee case, we discuss conditions under which walls form (or not), and quantify how these outcomes depend on parameters such as the energy difference between the false and true vacua and the expansion rate of the Universe. Various biased initial conditions are also addressed in appendices. Finally, we briefly comment on the possible cosmological implications of our results.

    hep-phastro-ph.COPRD(2025)·2 citations
16. 16*

    Constraints from muon $g-2$ on a gauged non-universal $U(1{)}_X$ model with inverse see-saw neutrinos

    J. S. Alvarado🇫🇷 · R. Martinez🇨🇴 · Cristian Sierra🇨🇳

    We study the effects on a non-universal $U(1{)}_X$ extension of the Standard Model given the alternative value obtained by the Budapest-Marseille-Wuppertal (BMW) group for the anomalous magnetic moment of the muon $g-2$. The model explains the fermion mass hierarchy through the non-universality of the extra gauge symmetry and by an additional ${\mathbb{Z}}_2$ discrete symmetry, where the heaviest fermions acquire their masses from two different scales determined by two Higgs doublets and one singlet, whereas the lightest fermions obtain their masses from radiative corrections. From cancellation of chiral anomalies, the model also includes heavy extra fermions, both charged and neutral. The latter are right-handed neutrinos that acquire masses via an inverse see-saw mechanism, reproducing the observed squared mass differences for the active neutrinos. Using the latest lattice calculation of the leading hadronic vacuum polarization (HVP) contribution to the muon $g-2$, we compute the dominant one-loop diagrams mediated by the $W$ and charged Higgs bosons, both with a heavy Majorana neutrino in the loop, setting bounds for masses of the new particles. We also provide predictions for observables that can probe our model in the future such as charged lepton flavor violating searches at Belle II like $\tau \to \mu \gamma$, $\tau \to e\gamma$ and at MEG II for $\mu \to e\gamma$.

    hep-ph1 citation
17. 17*

    NNLO predictions with nonlocal subtractions and fiducial power corrections in GENEVA

    Simone Alioli🇮🇹 · Georgios Billis🇮🇹 · Alessandro Broggio🇦🇹 · Giovanni Stagnitto🇮🇹

    We present the implementation of next-to-next-to-leading order (NNLO) QCD fully-differential corrections within the GENEVA framework, for both colour-singlet and colour-singlet+jet processes at hadron colliders, by employing a nonlocal subtraction approach. In particular, we discuss the implementation details and the challenges that arise when utilizing a dynamical infrared cutoff parameter. Additionally, we combine the subtraction with the projection-to-Born method in order to include fiducial power corrections. As a test case, we provide predictions for Drell-Yan and $Z$+jet production at the LHC, using $N$-jettiness as resolution variable. We validate the NNLO corrections of GENEVA against NNLOJET finding excellent agreement. Finally, we discuss how to extend our method to calculate the N${}^3$LO QCD fully-differential corrections to colour-singlet production at hadron colliders.

    hep-phhep-exJHEP(2026)·11 citations
18. 18*

    $27\otimes 27$

    Florian Cougoulic🇵🇱 · Stéphane Peigné🇫🇷

    We study the decomposition into $SU(N)$ irreducible representations (irreps) of the tensor product $27\otimes 27$, where $27$ is the highest-dimensional $SU(N)$ irrep present in a two-gluon system, and explicitly construct all Hermitian projectors on these irreps, as well as transition operators between them. This yields an explicit basis of the complete $27\otimes 27$ color space (defined as the space of $27\otimes 27\to 27\otimes 27$ color maps) in terms of orthogonal multiplets. This study shows that even complex color structures can be addressed, with the help of the birdtrack pictorial technique, using only elementary tools. In particular, we highlight the usefulness of the quadratic Casimir operator, whose eigenspaces allow efficient filtering of all projectors and transition operators, and of the permutation operators that further improve this filtering. The product $27\otimes 27$ also has an interesting feature: three equivalent irreps $27$ appear in the decomposition, two of which are symmetric and can therefore be distinguished neither by the quadratic Casimir operator nor by their symmetry under permutation. In this case, it is convenient to use Clebsch-Gordan coefficients to derive the two associated, symmetric projectors. The latter are not uniquely determined (only their sum is), and we give the set of all solutions. Finally, we explicitly derive the soft anomalous dimension matrix associated with $27\otimes 27\to 27\otimes 27$, whose block-diagonal main structure is easy to understand, but whose detailed spectrum properties remain intriguing. The approach presented for $27\otimes 27\to 27\otimes 27$ could in principle be applied to any product of $SU(N)$ irreps, and eventually automated.

    hep-phhep-thJ.Math.Phys.(2025)·1 citation
19. 19*

    Determination of the first-generation quark couplings at the Z-pole

    Krzysztof Mękała🇩🇪 · Daniel Jeans🇯🇵 · Jürgen Reuter🇩🇪 · Junping Tian🇯🇵 · Aleksander Filip Żarnecki🇵🇱

    Electroweak Precision Measurements are stringent tests of the Standard Model and sensitive probes to New Physics. Accurate studies of the $Z$-boson couplings to the first-generation quarks, which are currently constrained from LEP data to a few percent, could reveal potential discrepancies from the theory predictions. Future $e^{+}{e}^{-}$ colliders running at the $Z$-pole would be an excellent tool for an analysis based on a comparison of radiative and non-radiative $Z$ boson decays. In this paper, we present a method to extract the values of the $Z$ couplings to light quarks and discuss the uncertainty of the measurement, including contributions from various systematic effects. We show that systematic uncertainty in the heavy-flavour tagging performance is the key factor in the analysis and reducing it to a sub-permille level might be crucial to fully profit from the high luminosity of future $e^{+}{e}^{-}$ machines. The measurement could improve the LEP results by at least an order of magnitude.

    hep-phhep-exJHEP(2025)·3 citations
20. 20*

    Electroweak corrections to ${\tau }^{+}{\tau }^{-}$ production in ultraperipheral heavy-ion collisions at the LHC

    Stefan Dittmaier🇩🇪 · Tim Engel🇩🇪 · Jose Luis Hernando Ariza🇩🇪 · Mathieu Pellen🇩🇪

    While the anomalous magnetic moments of the electron and the muon have been measured with remarkable precision, the magnetic moment of the $\tau$-lepton is only known to rather limited precision. A promising approach to measure it exploits ${\tau }^{+}{\tau }^{-}$ production in ultraperipheral collisions of lead ions at the LHC. In this article, a state-of-the-art theory prediction for ${\tau }^{+}{\tau }^{-}$ production including leptonic $\tau$-decays is provided. The impact of spin correlations between the $\tau$-leptons, of the masses of final-state leptons, of next-to-leading-order electroweak corrections, and of the parametrization of the photon flux are discussed.

    hep-phJHEP(2025)·21 citations
21. 21*

    Combined Evidence for the $X_{17}$ Boson After PADME Results on Resonant Production in Positron Annihilation

    Fernando Arias-Aragón🇮🇹 · Giovanni Grilli di Cortona🇮🇹 · Enrico Nardi🇮🇹 · Claudio Toni🇫🇷

    The Positron Annihilation into Dark Matter Experiment at the Laboratori Nazionali di Frascati has reported an excess of $e^{+}{e}^{-}$ final-state events from positron annihilation on fixed-target atomic electrons. While the global significance remains at the $(1.77\pm 0.15)\sigma$ level, the excess is centered around $\sqrt{s}\sim 17\text{MeV}$, coinciding with the invariant mass at which anomalous $e^{+}{e}^{-}$ pair production has previously been observed in nuclear transitions from excited to ground states in ${}^8$Be, ${}^4$He and ${}^{12}$C, thereby strengthening the case for a common underlying origin, possibly involving a hypothetical new $X_{17}$ boson. We discuss the significance of this independent accelerator-based evidence. Combining it with existing nuclear physics results, we obtain a value for the $X_{17}$ mass of $m_{X_{17}}=16.88\pm 0.05\text{MeV}$, reducing the uncertainty from nuclear physics determinations by more than a factor of two, and mitigating the impact of poorly known correlations among their systematic errors.

    hep-phhep-exnucl-exnucl-thEPJC(2026)·11 citations
22. 22*

    Strengthening Anomaly Awareness

    Adam Banda🇺🇸 · Charanjit K. Khosa🇬🇧 · Veronica Sanz🇪🇸

    We present a refined version of the Anomaly Awareness framework for enhancing unsupervised anomaly detection. Our approach introduces minimal supervision into Variational Autoencoders (VAEs) through a two-stage training strategy: the model is first trained in an unsupervised manner on background data, and then fine-tuned using a small sample of labeled anomalies to encourage larger reconstruction errors for anomalous samples. We validate the method across diverse domains, including the MNIST dataset with synthetic anomalies, network intrusion data from the CICIDS benchmark, collider physics data from the LHCO2020 dataset, and simulated events from the Standard Model Effective Field Theory (SMEFT). The latter provides a realistic example of subtle kinematic deviations in Higgs boson production. In all cases, the model demonstrates improved sensitivity to unseen anomalies, achieving better separation between normal and anomalous samples. These results indicate that even limited anomaly information, when incorporated through targeted fine-tuning, can substantially improve the generalization and performance of unsupervised models for anomaly detection.

    hep-phcs.LG3 citations
23. 23*

    Detecting Ultralight Dark Matter with Matter Effect

    Xucheng Gan🇩🇪 · Da Liu🇺🇸 · Di Liu🇫🇷 · Xuheng Luo🇺🇸 · Bingrong Yu🇺🇸

    Ultralight particles, with a mass below the electronvolt scale, exhibit wave-like behavior and have arisen as a compelling dark matter candidate. A particularly intriguing subclass is scalar dark matter, which induces variations in fundamental physical constants. However, detecting such particles becomes highly challenging in the mass range above $10^{-6}\text{eV}$, as traditional experiments face severe limitations in response time. In contrast, the matter effect becomes significant in a vast and unexplored parameter space. These effects include (i) a force arising from scattering between ordinary matter and the dark matter wind and (ii) a fifth force between ordinary matter induced by the dark matter background. Using the repulsive quadratic scalar-photon interaction as a case study, we develop a unified framework based on quantum mechanical scattering theory to systematically investigate these phenomena across both perturbative and non-perturbative regimes. Our approach not only reproduces prior results obtained through other methodologies but also covers novel regimes with nontrivial features, such as decoherence effects, screening effects, and their combinations. In particular, we highlight one finding related to both scattering and background-induced forces: the descreening effect observed in the non-perturbative region with large incident momentum, which alleviates the decoherence suppression. Furthermore, we discuss current and proposed experiments, including inverse-square-law tests, equivalence principle tests, and deep-space acceleration measurements. Notably, we go beyond the spherical approximation and revisit the MICROSCOPE constraint on the background-induced force in the large-momentum regime, where the decoherence and screening effects interplay. The ultraviolet models realizing the quadratic scalar-photon interaction are also discussed.

    hep-phastro-ph.COhep-exhep-thJHEP(2026)·29 citations
24. 24*

    Searching for the QCD Dark Matter Axion

    Masha Baryakhtar🇺🇸 · Leslie Rosenberg🇺🇸 · Gray Rybka🇺🇸

    Proposed half a century ago, the quantum chromodynamics (QCD) axion explains the lack of charge and parity violation in the strong interactions and is a compelling candidate for cold dark matter. The last decade has seen the rapid improvement in the sensitivity and range of axion experiments, as well as developments in theory regarding consequences of axion dark matter. We review here the astrophysical searches and theoretical progress regarding the QCD axion. We then give a historical overview of axion searches, review the current status and future prospects of dark matter axion searches, and then discuss proposed dark matter axion techniques currently in development.

    ↳ hep-exastro-ph.COhep-ph20 citations
25. 25*

    Hints for a Geon from Causal Dynamic Triangulations

    Axel Maas🇦🇹 · Simon Plätzer🇦🇹 · Felix Pressler🇦🇹

    The existence of geons, physical states of self-bound gravitons, has long been proposed. In the context of four-dimensional causal dynamical triangulation simulations we investigate this possibility by measuring curvature-curvature correlators of different gravitational operators. We find a behavior consistent with a massive state, independent of the operators considered, over a certain distance window. While at most a hint, this is tantalizing due to its possible implications for dark matter or (primordial) black holes. We also find indications that the phase of rapid expansion of the obtained de Sitter universe impacts the mass, and relates to quantum fluctuations of space-time.

    ↳ hep-latgr-qchep-phhep-thPLB(2026)·6 citations
26. 26*

    More fields are different: Stochastic view of multi-field inflationary scenario

    Tomo Takahashi🇯🇵 · Koki Tokeshi🇫🇷

    High-energy physics often motivates multi-field inflationary scenarios where stochastic effects play a crucial role. Peculiar to multi-field models, the noise-induced centrifugal force results in a longer duration of inflation depending on the number of fields, even when the stochastic noises themselves are small. We show that, in such small-noise regimes, the number of fields generically discriminates whether inflation successfully terminates or lasts forever. Our results indicate that inflation with an extremely large number of fields may fail to realise our observable Universe.

    ↳ astro-ph.COgr-qchep-phhep-th5 citations
27. 27*

    Relic gravitational waves from primordial gravitational collapses

    Xiang-Xi Zeng🇨🇳 · Zhuan Ning🇨🇳 · Zi-Yan Yuwen🇨🇳 · Shao-Jiang Wang🇨🇳 · Heling Deng🇺🇸 · Rong-Gen Cai🇨🇳

    A large primordial density perturbation of the Hubble scale will gravitationally collapse, generating an outgoing sound shell, whether or not a primordial black hole (PBH) is formed. In this Letter, we report a hybrid numerical analysis of the stochastic gravitational wave background induced by the collision of sound shells in the early Universe. The peak frequency and amplitude in the GW spectrum depend on the Hubble horizon and the abundance of sound shells. Abundant density perturbations would lead to GW backgrounds potentially detectable for future pulsar timing arrays and ground-based/space-borne detectors. For those perturbations that collapse into PBHs, future null detection of the corresponding high-frequency GW background could put new observational constraints on those PBHs that have already evaporated.

    ↳ gr-qcastro-ph.COhep-ph15 citations
28. 28*

    Constraints on Generalized Gravity-Thermodynamic Cosmology from DESI DR2

    Udit K. Tyagi🇦🇺 · Sandeep Haridasu🇮🇹 · Soumen Basak🇮🇳

    We explore the cosmological implications of generalized entropic models within the framework of Gravity-Thermodynamics (GT) approaches. These models, characterized by three or four additional free parameters, are designed to capture deviations from the standard Bekenstein-Hawking entropy and can reproduce well-known entropic formulations, including Tsallis, Rényi, Sharma-Mittal, Barrow, Kaniadakis, and Loop Quantum Gravity entropies in various analytical limits. We implement the corresponding cosmological models using a fully numerical GT approach to constrain the model parameters and to study the evolution of the dark energy equation of state as a function of the scale factor. Our Bayesian analysis, which incorporates the Pantheon+ and DESy5 supernovae data alongside the recently released DESI-DR2/DR1 Baryon Acoustic Oscillation (BAO) measurements, shows that the data favor the standard Bekenstein-Hawking entropy, leading to a $\Lambda$CDM-like late-time behavior. In this context, the three-parameter (${\mathcal{S}}_3$) entropic model appears to be sufficient to capture the observed dark energy phenomenology. Furthermore, a direct comparison of the Bayesian evidence indicates that the three-parameter model is preferred over the four-parameter (${\mathcal{S}}_4$) variant by a factor of $\Delta \log \mathcal{B}\sim -6$, while the GT approach as a whole is significantly disfavored relative to the $\Lambda$CDM model with at least $\Delta \log \mathcal{B}\sim -8$ (${\mathcal{S}}_3$) to $\Delta \log \mathcal{B}\sim -13$ (${\mathcal{S}}_4$), when using the DESy5 and DESI-DR2 datasets.

    ↳ astro-ph.COgr-qchep-phPRD(2026)·17 citations
29. 29*

    Role of Matter Inhomogeneity on Fast Flavor Conversion of Supernova Neutrinos

    Soumya Bhattacharyya🇹🇼 · Meng-Ru Wu🇹🇼 · Zewei Xiong🇩🇪

    We study how a spatially varying matter potential $\lambda$, arising from neutrino-electron forward scattering, affects the onset, evolution, and nonlinear outcome of fast neutrino flavor conversions (FFCs) triggered by the presence of zero crossings in the angular distribution of the neutrino electron lepton number (ELN). We find that increasing the spatial variation rate of $\lambda$ can strongly influence FFC dynamics and even stabilize systems that are otherwise unstable. Using stability analysis based solely on initial conditions, we identify for the first time a critical variation rate above which no FFC occurs even if the flavor instability exists. Below this critical rate, a substantial $\lambda$ variation delays the onset of FFCs and quickly generates small-scale, incoherent features in the nonlinear regime, which leads to a similar coarse-grained outcome that eliminates the ELN crossing as in the homogeneous case. Our findings emphasize the need to consider matter inhomogeneity in improved supernova models accounting for FFCs, and we propose simple analytical ways to incorporate this effect.

    ↳ astro-ph.HEastro-ph.COastro-ph.SRhep-ph+113 citations
30. 30*

    Transforming Simulation to Data Without Pairing

    Eli Gendreau-Distler🇺🇸 · Luc Le Pottier🇺🇸 · Haichen Wang🇺🇸

    We explore a generative machine learning-based approach for estimating multi-dimensional probability density functions (PDFs) in a target sample using a statistically independent but related control sample - a common challenge in particle physics data analysis. The generative model must accurately reproduce individual observable distributions while preserving the correlations between them, based on the input multidimensional distribution from the control sample. Here we present a conditional normalizing flow model (CNF) based on a chain of bijectors which learns to transform unpaired simulation events to data events. We assess the performance of the CNF model in the context of LHC Higgs to diphoton analysis, where we use the CNF model to convert a Monte Carlo diphoton sample to one that models data. We show that the CNF model can accurately model complex data distributions and correlations. We also leverage the recently popularized Modified Differential Multiplier Method (MDMM) to improve the convergence of our model and assign physical meaning to usually arbitrary loss-function parameters.

    ↳ physics.data-anhep-exhep-ph0 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.