Mon·Jun 8, 2026Monday·June 8, 2026

1. 01*

   Discovering the Axiverse via Fifth Forces

   Martin Bauer🇬🇧 · Francesca Chadha-Day🇬🇧 · Alexander Eberhart🇬🇧

   If the Universe is described by string theory or other extensions of the Standard Model, several light, axion-like states are predicted to exist. However, most experiments only search for one of these states. We show that searches for fifth forces can't assume a non-relativistic potential induced by a single axion field. We discuss the strength of the non-relativistic spin-dependent and spin-independent potentials in the most general case of $N_a$ different axions and show how the shape of the potentials can be used to distinguish between different axiverse scenarios.

   hep-ph1 citation
2. 02*

   Photons, jets and missing momentum from a two-vector dark sector

   Yara do Amaral Coutinho🇧🇷 · Benjamin Fuks🇫🇷 · Mark D. Goodsell🇫🇷 · Bertrand Laforge🇫🇷 · José Ocariz🇫🇷 · Farinaldo S. Queiroz🇧🇷 · Yoxara Villamizar🇫🇷

   We investigate the LHC phenomenology of a vector dark-sector effective theory containing two neutral massive vector states, both odd under a dark-parity symmetry. The lightest state is stable and provides a dark-matter candidate, while the leading interactions with the Standard Model arise from dimension-six operators involving the hypercharge field strength. In the prompt-decay regime considered in this work, the heavier state can decay radiatively, leading to a $\gamma +\text{jets}+E_T^{\text{miss}}$ signature when the two dark vectors are produced in association with QCD radiation. We study this topology at the LHC through a cut-based analysis, comparing an inclusive missing-transverse-momentum selection with a three-bin strategy that retains coarse shape information. The binned analysis is found to substantially improve the expected reach and probes regions of the parameter space compatible with the observed relic abundance in the standard freeze-out scenario. We also discuss the freeze-in interpretation and the limitations associated with the EFT description at high masses.

   hep-phhep-thJHEP(2026)·0 citations
3. 03*

   Neutrino Oscillations as an Open Quantum System in Strong Gravitational Fields: Spin-Connection Decoherence and Kerr Frame Dragging

   Gayatri Ghosh🇮🇳

   We investigate neutrino flavor evolution in strong gravitational fields within an open-quantum-system framework in curved spacetime. Starting from the Dirac equation in the vierbein formalism, we construct an effective flavor Hamiltonian incorporating gravitational redshift, spin--curvature couplings, and Kerr frame-dragging effects. Treating spin-connection fluctuations as a stochastic gravitational environment, we derive a Lindblad master equation and introduce a curvature-enhanced decoherence rate governed by local spacetime geometry. We compute oscillation probabilities, coherence loss, flavor-ratio distortions, entanglement entropy generation, and event-rate modifications for neutrinos propagating near Schwarzschild and Kerr compact objects. The resulting signatures are compared with projected sensitivities of IceCube-Gen2, KM3NeT, and P-ONE, and are further quantified through detector-level significance estimates. Our results provide a unified effective framework linking neutrino oscillations, gravitationally induced decoherence, quantum-information observables, and high-energy astrophysical neutrino measurements in strong-curvature environments.

   hep-ph0 citations
4. 04*

   micrOMEGAs 7: Beyond standard cosmology

   G. Belanger🇫🇷 · A. Belyaev🇬🇧 · N. Bernal🇦🇪 · F. Boudjema🇫🇷 · S. Chakraborti🇬🇧 · A. Goudelis🇫🇷 · A. Pukhov🇷🇺

   We present micrOMEGAs7, a major upgrade of the micrOMEGAs package for the computation of dark matter observables in generic models. This release introduces a generalized treatment of the Boltzmann equations, allowing for user-defined modifications of the Hubble expansion rate, entropy evolution, and non-thermal dark matter production from late-decaying cosmological components, thereby extending the framework beyond the standard radiation-dominated cosmology. The relic density can now be computed in scenarios such as low-temperature reheating, early matter domination, and kination. The new version also improves the treatment of sub-GeV dark matter, in particular annihilation into light mesons through scalar mediators, and provides updated spectra for indirect detection. Several experimental and observational constraints have been implemented or revised, including CMB bounds from Planck on energy injection during recombination and Fermi-LAT limits from dwarf spheroidal galaxies. For direct detection, a recast of recent LZ results has been included, and the code now takes into account effective electromagnetic couplings of spin-$1/2$ and spin-1 dark matter. Collider observables have also been extended through the implementation of CMS dilepton resonance constraints on $Z^{\prime }$ mediators. Additional improvements include a more flexible treatment of effective relativistic degrees of freedom and an updated LHAPDF interface.

   hep-ph5 citations
5. 05*

   A more effective QCD string at colliders: Decay of excited strings and the worldsheet axion

   Ethan Carragher🇬🇧 · John March-Russell🇬🇧

   The confining flux tube of $(3+1)$d QCD is described by an effective string theory with $(1+1)$d worldsheet action that extends the Nambu-Goto form by the addition of a massive pseudoscalar worldsheet ``axion". As argued in companion papers concerning the modified phenomenology of the Lund string model at colliders, QCD flux tubes produced by high-energy collisions are likely to involve excitation of both worldsheet Nambu-Goldstone and axion modes, although the standard Lund model assumes a constant tension ground-state string. Here we detail the path-integral computation of the modified Schwinger-like process of string breaking via nucleation of quark-antiquark pairs in the presence of excitations above the string ground state. We find that the worldsheet axion leads to the dominant change in the string breaking process, the axion excitations producing, among other effects, a varying effective tension of the string, which can exponentially enhance or suppress the string breaking rate depending on the local phase of the excitation. Our computation employs a version of the Schwinger-Keldysh complex time contour method with initial state data specified by a density matrix. In an excited background the Euclidean saddle point is generically complex, but its continuation gives real initial data for post-decay evolution. Our results are of relevance for hadronisation models with excited QCD strings.

   hep-phhep-th0 citations
6. 06*

   Lepton interactions from GeV to EeV

   Reinaldo Francener🇧🇷

   In this work, we investigate the phenomenological consequences of neutrino and muon interactions with matter. In our studies, we focused in phenomenological predictions for two experiments: FASER and IceCube. FASER is a detector located at the LHC that measures neutrinos produced in proton-proton collisions. A new version of FASER, FASER2, has been proposed to operate in the Forward Physics Facility during the high-luminosity regime of the LHC. The intense flux of tau neutrinos expected at FASER2 motivated us to study the polarization effects of the tau produced in charged current interactions. Our results show that the produced taus will not be completely polarized. Among the Standard Model particles, only neutrinos and muons produced in proton-proton collisions at the LHC can reach FASER. In our study, we show that muon-initiated events can reveal interesting nucleon properties, such as nuclear effects and the existence of an intrinsic charm. The high number of events induced by neutrinos at FASER motivated us to study rare processes in neutrino interaction, such as the neutrino trident. Our results indicate that the neutrino trident process can be observed at FASER2. We have also studied muon trident at the LHC, and we showed that tau pair production can be observed for the first time in this reaction. In contrast to neutrinos detected at the LHC, the neutrinos observed at IceCube come from natural sources, being mainly atmospheric and astrophysical neutrinos. IceCube is capable of observing neutrinos across a wide energy spectrum, ranging from a few GeV to beyond PeV. We show that the study of these events can contribute to our understanding of the structure of target hadrons, as well as the search for physics effects beyond the Standard Model in the propagation of these neutrinos in the universe until they reach the Earth.

   hep-phastro-ph.HEhep-exnucl-th0 citations
7. 07*

   Investigation of fully heavy tetraquark within chiral quark model

   Yuheng Wu🇨🇳 · Xuejie Liu🇨🇳 · Ye Yan🇨🇳 · Yue Tan🇨🇳 · Qi Huang🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

   In the framework of the Chiral quark model (ChQM), we investigate the fully charmed and fully bottomed tetraquark with $J^{PC}=2^{++}$ including two structures: $Q\bar{Q}-Q\bar{Q}$ and $QQ-\bar{Q}\bar{Q}$. The bound-state calculation shows that there is no bound state in either $cc\bar{c}\bar{c}$ or $bb\bar{b}\bar{b}$ systems. However, by using the real-scaling method, some resonance states are obtained. For the $cc\bar{c}\bar{c}$ system, when the channel-coupling includes only three $S$-wave channels, two resonant states are obtained: one with a mass around $7002$ MeV and decay width near $54$ MeV, and another with a mass around $7227$ MeV and a decay width near $66$ MeV. The former can be regarded as a candidate for the $X(6900)$, and the latter can be considered as a candidate for the $X(7200)$. Upon adding the ${\chi }_{c0}{\chi }_{c2}$, ${\chi }_{c1}{\chi }_{c1}$, ${\chi }_{c1}{\chi }_{c2}$, ${\chi }_{c2}{\chi }_{c2}$ channels, both resonant states still remain. For the $bb\bar{b}\bar{b}$ system, only one resonant state is obtained, regardless of whether the four channels composition of the excited mesons are included or excluded. The mass and width of this resonant state are around $19743$ MeV and $67$ MeV, respectively. We suggest that future experiments search for the possible resonance state in the invariant mass spectrum of ${\rm Y}{\rm Y}$ or ${\rm Y}{\rm Y}(2S)$.

   hep-ph1 citation
8. 08*

   Macroscopic Quantum Interference in Dark Matter Wave Scattering with MICROSCOPE

   Cheng-Tao Fu🇨🇳 · Peng-Shun Luo🇨🇳 · Rui Luo · Jie Sheng🇯🇵 · Chuan-Yang Xing🇨🇳

   Ultralight dark matter behaves as a coherent wave, yet its quantum interference effects of elastic scattering with multiple targets have remained unexplored. We show that the nested test masses of MICROSCOPE realize such an ``interferometer'' for dark-matter wave scattering. Amplitudes from the two concentric cylinders interfere and redistribute the induced force between them. This effect produces unique and rotation-modulated signals set by the target geometry. Developing the theoretical framework and applying it to MICROSCOPE data, we obtain leading constraints on quadratic dark-matter--nucleon coupling for masses $10^{-3}$--$10^{-2}$eV, reaching cross sections of order $10^{-52}$ cm${}^2$.

   hep-phhep-ex2 citations
9. 09*

   Mechanical distribution of the pseudoscalar charmonium and bottomonium on the light-front

   Ashutosh Dwibedi🇮🇳 · Satyajit Puhan🇹🇼 · Sabyasachi Ghosh🇮🇳

   We investigate the energy-momentum tensor of pseudoscalar charmonium and bottomonium within the framework of the light-front quark model. The gravitational form factors (GFFs), namely the $A$ and $D$-terms, are evaluated in terms of the light-front wave functions. The corresponding spatial mechanical distributions in the transverse plane are obtained through the Fourier transform of these GFFs. To examine the sensitivity of the results to the internal quark-antiquark distribution inside the meson, two distinct Gaussian forms are employed for the spatial part of the wave function. We analyze several mechanical properties in the transverse plane, including the momentum density, pressure distribution, shear stress, force density, and internal energy density. The pressure distribution exhibits a node where it changes sign from positive (repulsive) to negative (attractive) with increasing transverse distance. The force distribution remains positive throughout the transverse plane, supporting the stability condition proposed in earlier studies. Most of the spatial distributions, except for the shear stress, are found to be sensitive to the choice of the spatial wave function near the center of the meson, while they become nearly insensitive toward the periphery. In contrast, the shear stress distribution exhibits noticeable sensitivity to the choice of wave function in the intermediate transverse region.

   hep-phnucl-th3 citations
10. 10*

    Joint probes of dark matter annihilation from neutrino detectors and CMB targets

    Ruifeng Leng🇨🇳 · Shao-Ping Li🇦🇹

    Dark matter (DM) annihilation into neutrinos provides a promising observational channel targeted by current and forthcoming neutrino detectors. However, the detection of such neutrino fluxes alone cannot uniquely determine their astrophysical or cosmological origin, such as the recent observations from Super-Kamiokande that hint at a small excess of electron antineutrino events. We propose that the effective number of neutrino species and the spectral distortion of the cosmic microwave background (CMB) can serve as complementary observables to probe neutrino signatures from DM annihilation. Using a simple model-independent analysis, we determine the detection windows of these cosmic observables that overlap with the experimental sensitivities from the Super-Kamiokande, Jiangmen Underground Neutrino Observatory, Hyper-Kamiokande, and the Deep Underground Neutrino Experiment, showing that joint probes of large DM annihilation to neutrinos with MeV-GeV masses can be achieved by neutrino detectors and CMB experiments.

    hep-phastro-ph.CO0 citations
11. 11*

    VALO1.0: New real-photon parton distributions with Monte Carlo uncertainties

    Madhav Chithirasreemadam (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮 · Vadim Guzey (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮 · Felix Hekhorn (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮 · Ilkka Helenius (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮 · Hannu Paukkunen (Jyvaskyla U. and Helsinki Inst. of Phys.)🇫🇮

    Performing a global QCD analysis of data on the photon structure function $F_2^{\gamma }$ in $e^{+}{e}^{-}$ scattering, we determine new leading order (LO) and next-to-leading (NLO) parton distributions functions (PDFs) of the real photon. The resulting photon PDFs, referred to as VALO1.0, are obtained in the form of Monte Carlo (MC) replicas which assess the propagation of experimental uncertainties to the PDFs. To achieve well-converging fits, we employ a five-parameter hadron-like ansatz for the boundary conditions with simplifying assumptions on the flavor structure of the quark distributions and the large-$x$ behavior of the gluon distribution. This results in robust quark distributions at both LO and NLO and the gluon distribution at NLO with modest uncertainties, while leaving LO gluons still largely unconstrained. The resulting photon PDFs broadly agree with the parameterizations available in the literature and set the stage for future analyses including additional photoproduction data, which could help to increase the flexibility of our input PDFs. The LO and NLO VALO1.0 photon-PDF replicas, both in the DIS${}_{\gamma }$ and $\overline{\mathrm{MS}}$ factorization schemes as well as the open-source $\gamma \text{EKO}$ code for solving the scale dependence of photon PDFs and the analysis framework $\text{VALOfitter}$ are made publicly available.

    hep-ph2 citations
12. 12*

    Simultaneous Dalitz-plot decomposition of the $e^{+}{e}^{-}\to J/\psi \pi \pi (K\bar{K})$ processes in the 4.13-4.36 GeV region using dispersive final-state interactions

    Viktoriia Ermolina🇩🇪 · Igor Danilkin🇩🇪 · Marc Vanderhaeghen🇩🇪

    We present a joint analysis of the processes $e^{+}{e}^{-}\to J/\psi {\pi }^{+}{\pi }^{-}$ and $e^{+}{e}^{-}\to J/\psi K^{+}{K}^{-}$ at center-of-mass energies from 4.13 to 4.36 GeV. The amplitudes are constructed using the Dalitz-plot decomposition formalism, with the $e^{+}{e}^{-}$ energy dependence encoded through the $Y(4220)$ and $Y(4320)$ resonant structures together with a non-resonant production mechanism. The scalar $\pi \pi /K\bar{K}$ final-state interaction is treated dispersively using a coupled-channel Omnès representation. This allows us to describe the measured total cross sections and one-dimensional invariant-mass distributions with a single set of energy-independent parameters. We find that a purely resonant description of the BESIII data is insufficient, requiring a non-resonant term at the amplitude level which undergoes $\pi \pi /K\bar{K}$ rescattering. Within the present isobar model, we extract Breit-Wigner parameters for the $Z_c(3900)$, $Y(4220)$, and $Y(4320)$ states, and determine the corresponding subprocess cross sections.

    hep-ph1 citation
13. 13*

    Current and future constraints on heavy New Physics from $\tau$ weak dipole moments

    Nejc Košnik🇸🇮 · Zachary Polonsky🇨🇭 · Aleks Smolkovič🇸🇮

    We study the weak magnetic and electric dipole moments of the $\tau$ lepton as precision tests of the Standard Model (SM) and probes of heavy New Physics (NP). We present an updated SM prediction for the $\tau$ weak magnetic dipole moment at one loop, including a careful assessment of theoretical uncertainties from electroweak scheme dependence. Working within the SM Effective Field Theory, we derive comprehensive current constraints on the $\tau$ dipole operators from a combination of observables: the $\tau$ weak and electromagnetic dipole moments, high-mass Drell-Yan tails at the LHC, $Z$ partial decay widths, and the electron electric dipole moment. Finally, we assess the prospects of measuring the SM value of the $\tau$ weak magnetic moment at the FCC-$ee$ Tera-$Z$ run, and project the sensitivities of the leading observables to heavy NP at FCC-$ee$ and HL-LHC, paying particular attention to systematic uncertainties. We find that the $\tau$ weak dipole moments are already among the leading probes of the $\tau$ dipole operators, and will become increasingly dominant at future colliders.

    hep-phhep-ex1 citation
14. 14*

    Correlating lepton flavor violating $b\to s$ and leptonic decay modes in a minimal abelian extension of the Standard Model

    Davide Milillo🇮🇹

    We examine possible correlations between $b\to s{\ell }_1^{-}{\ell }_2^{+}$ transitions -- both in the lepton flavor conserving (${\ell }_1={\ell }_2$) and violating case (${\ell }_1\ne {\ell }_2$) -- and purely leptonic flavor violating decays within the ABCD model [1], a minimal abelian extension of the Standard Model (SM) introducing a new $\text{U}(1{)}^{\prime }$ symmetry. The associated neutral $Z^{\prime }$ boson has generation-dependent, flavor non-universal couplings to SM fermions, governed by three rational parameters ${ϵ}_{1,2,3}$, which sum to zero to ensure gauge anomaly cancellation. Each ${ϵ}_i$ is common to all fermions of a given generation, thus inducing correlations among quark and lepton observables. For lepton flavor conserving (LFC) processes, only small deviations from SM predictions were found [2], reflecting the mutual constraints between the quark and lepton sectors, which preclude large discrepancies. On the other hand, the model allows tree-level lepton flavor violating (LFV) decays, yielding correlations between LFV $b\to s$ transitions and charged lepton decays. The analysis of such correlations shows that the current experimental upper bounds for the rates of ${\tau }^{-}\to {\mu }^{-}{\mu }^{+}{\mu }^{-}$, \ ${\mu }^{-}\to e^{-}\gamma$, \ ${\mu }^{-}\to e^{-}{e}^{+}{e}^{-}$ and ${\mu }^{-}\to e^{-}$ conversion in nuclei constrain branching ratios of LFV $B_{(s)}$ decays in hierarchical order [2].

    hep-phhep-exhep-latPoS(2026)·0 citations
15. 15*

    Two-Pole Structure of $\Lambda (1405)$ with Temporal Evolution and Spatial Distribution

    Yu Zhuge🇨🇳 · Zhan-Wei Liu🇨🇳

    The $\Lambda (1405)$ is a special hadron resonance associated with two poles of the scattering amplitudes, and its nature remains under debate since its discovery before the birth of the quark model. In this work we study the structures of these two poles and their temporal evolution, including their difference, interference, and synergy. Each pole can usually be represented by the Gamow vector $|{\psi }^{\mathrm{Gamow}}⟩$ in the complex momentum space $|\vec{p}{e}^{-i\theta }⟩$. We construct its representation $|{\psi }^{\mathrm{phys}}⟩$ in the real momentum space $|\vec{p}⟩$ through the analytic continuation of the Gamow wavefunction, which also satisfies the Hamiltonian eigenvalue equation with the assistance of a virtual state vector. Both the decreasing behavior of the resonance and the production of the decayed scattering states can be simultaneously described by the temporal evolution $|{\psi }^{\mathrm{phys}},t⟩=\exp (-iHt)|{\psi }^{\mathrm{phys}}⟩$. The state $|{\psi }^{\mathrm{phys}},t=0⟩$ gives the finite-range confinement of the resonance while $|{\psi }^{\mathrm{phys}},t\to \infty ⟩$ provides a Breit-Wigner-like distribution of the final scattering states whose appearance probability is nonzero as $r\to \infty$. In the two-channel system $\pi \Sigma$-$\bar{K}N$, we first dynamically generate the two poles of $\Lambda (1405)$ and then discuss their temporal evolutions and spatial distributions which can produce results consistent with experimental measurements such as the $\pi \Sigma$ invariant-mass spectrum and provide a new path to study hadron resonances.

    hep-ph0 citations
16. 16*

    Interpolation between Sudakov and BFKL rapidity evolutions for TMD factorization at small $x$

    Ian Balitsky🇺🇸

    Within the framework of rapidity-only small-$x$ TMD factorization, the evolution with respect to the rapidity cutoff is initially governed by Sudakov double logarithms and subsequently by BFKL/BK single logarithms. The evolution equation proposed in this paper correctly reproduces both the Sudakov and BFKL limits, while providing a consistent interpolation between these two regimes.

    hep-ph2 citations
17. 17*

    Searches for GeV-Scale ALPs at RHIC

    Kaori Fuyuto🇯🇵 · Claudio Andrea Manzari🇺🇸 · Hitoshi Murayama🇺🇸

    We point out that ultra-peripheral Au+Au collision data collected at the Relativistic Heavy Ion Collider, operational during 2000-2026, can be used to search for axion-like particles coupled to photons via the resonant process $\gamma \gamma \to a\to \gamma \gamma$. Exploiting the $Z^4$ enhancement of the two-photon luminosity in heavy-ion collisions and the low photon energy thresholds achievable at RHIC, we simulate signal and background processes, the latter dominated by light-by-light scattering, hadronic resonance production, and misidentified $e^{+}{e}^{-}$ pairs, and estimate upper limits on the ALP-photon coupling $g_{a\gamma \gamma }$ assuming $1.9{\text{nb}}^{-1}$ of existing data collected by the PHENIX experiment. We find sensitivity to ALP masses in the range $2\text{GeV}\lesssim m_a\lesssim 5\text{GeV}$ with couplings $g_{a\gamma \gamma }\gtrsim 4\times 10^{-4}{\text{GeV}}^{-1}$, probing previously unexplored regions of parameter space. Access to larger luminosity datasets could substantially extend the sensitivity of this search, motivating a dedicated analysis of ultra-peripheral collision data collected at RHIC by PHENIX as well as other experiments.

    hep-phhep-ex1 citation
18. 18*

    Core Composition Effects on the QCD Axion Mass Limit from Neutron Star Cooling

    Fernando Arias-Aragón🇪🇸 · Federico Nola🇮🇹

    Neutron stars are very dense media in which axions may be produced. This has been used to set limit on the QCD axion mass, usually under the assumption that only neutrons, protons, electrons, and muons appear in the star core. Given the extreme conditions reached within neutron stars, it is reasonable to consider that other particles, such as hyperons and $\Delta$ resonances, may exist on-shell. In this work, we study how the limit on the mass of QCD axions, namely KSVZ and DFSZ invisible axions, is altered when different equations of state are used, allowing for heavier particles to appear in the neutron star core. We find that this dependence is in general mild and thus reinforces the reliability of the known limit. Additionally, in the DFSZ scenario, it may drive the limit within the sensitivity window for IAXO. This would allow this experiment to discern the composition of neutron star cores if an axion were to be observed within that window.

    hep-phastro-ph.HE1 citation
19. 19*

    Detector performance at SHiP for cascade-produced long-lived particles

    Matei Climescu🇧🇪 · Yehor Kyselov🇺🇦 · Maksym Ovchynnikov🇨🇭

    Previous studies have shown that cascade production in the thick target of the SHiP experiment may substantially enhance the number of light long-lived particles (LLPs) decaying in the fiducial volume. However, cascade-produced LLPs are typically soft, so daughter-level acceptance and reconstruction effects can strongly suppress the observable event rate. We quantify this suppression for two representative cases: photophilic axion-like particles produced in electromagnetic cascades, and heavy neutral leptons produced in decays of secondary kaons. We combine a semi-analytic event-rate calculation with a detector-level study of ALP reconstruction in the electromagnetic calorimeter. For the nominal SHiP detector design, cascade ALPs give at most a moderate enhancement over primary production, and only at the lightest masses; at higher masses, the cascade contribution becomes subdominant or negligible. For HNLs from secondary kaons, the cascade contribution is already subdominant after imposing daughter-level geometric acceptance. We also identify possible ways to recover part of the cascade event rate, including relaxed event-selection criteria and an active-target subdetector.

    hep-ph0 citations
20. 20*

    Open quantum system approach to the transverse momentum broadening of a colour dipole

    François Arleo🇫🇷 · Pietro Benzoni🇫🇷 · Paul Caucal🇫🇷 · Pol Bernard Gossiaux🇫🇷

    Using the open quantum systems formalism, we study the propagation of a quark-antiquark pair propagating through a dense QCD plasma of size $L$ and transverse momentum broadening transport coefficient $\hat{q}$, and we derive the Lindblad evolution equation for the density matrix of the system. We focus on the boosted regime where the opening angle ${\theta }_{q\bar{q}}$ of this effective colour dipole satisfies ${\theta }_{q\bar{q}}\ll 1$. In the correlation limit where the quark-antiquark relative transverse momentum $p_{\perp }$ is much larger than the imbalance $q_{\perp }$ as well as the medium typical transverse momentum scale $Q_s=\sqrt{\hat{q}L}$, we demonstrate that the resulting Wigner distribution displays quasi factorisation between a hard factor describing the hard splitting producing the $q\bar{q}$ pair and the transverse momentum imbalance $q_{\perp }$-distribution encoding the broadening induced by the medium. The factorisation is violated by a "colour decoherence" factor that controls the ${\theta }_{q\bar{q}}$ dependence of the $q_{\perp }$-distribution through the ratio ${\theta }_{q\bar{q}}/{\theta }_c$, with ${\theta }_c\sim (\hat{q}{L}^3{)}^{-1/2}$. The open quantum systems approach enables us to clarify the role of this critical angle ${\theta }_c$ and its associated critical time $t_c$ in the genuine quantum decoherence of the density matrix in colour and kinematic space: in particular, $t_c$ controls both the suppression of the off-diagonal elements of the density matrix in colour space and the transition between singlet and octet states. We find, however, that colour decoherence sets in earlier than the full decoherence of the density matrix, thereby marking the onset of classical behaviour in the system. Finally, we investigate the corrections beyond the quasi-factorised picture due to the quantum diffusion term in $p_{\perp }$ of the Lindblad equation and we find that these corrections are mild.

    hep-phnucl-th4 citations
21. 21*

    Dark Z' at a Muon Collider: Radiative Return versus Vector Boson Fusion

    Nicko Angelo Rabang🇵🇭 · Philip Tanedo🇺🇸 · Marvin Flores🇵🇭

    A secluded, massive Abelian gauge boson called a dark Z' may interact with the Standard Model through kinetic mixing and mass mixing in the Higgs sector. We determine the sensitivity of a future high-energy muon collider to discover such a particle and determine its mixing parameters. We examine a dark Z' with mass from 100 GeV up to the collider energy for a set of collider benchmarks up to 14 TeV. We show the discovery reach and compare to the current and proposed future colliders. A muon collider is sensitive to two complementary production modes: radiative return (muon fusion with an associated photon), and vector boson fusion of W bosons. An observable photon distinguishes these production modes and the relative rates of these processes allows one to determine the relative mixing. Soft and collinear photons in the radiative return diagram contribute to the same final state as vector boson fusion. We show that these relative rates alone can determine the mixing to an accuracy comparable to that of a fully polarized muon beam using a left-right asymmetry.

    hep-ph0 citations
22. 22*

    Flavor phenomenology of light dark particles

    Robert Ziegler🇩🇪

    We review the flavor phenomenology of light dark particles, focusing on axion-like particles with sub-GeV masses and generic flavor-violating couplings. Such states can naturally emerge from the spontaneous breaking of generic flavored symmetries, and are motivated by dark matter or the Strong CP Problem, with the QCD axion serving as a paradigmatic example. Light dark particles can be produced in two-body decays of Standard Model particles, giving rise to missing energy signals that can not only be observed in high-precision flavor experiments, but also be probed in core-collapse supernovae and the cosmic microwave background. These decays are controlled by dimension-five operators, which makes dedicated laboratory searches sensitive to very large UV scales up to $10^{12}\mathrm{GeV}$ and thus highly complementary to astrophysical and cosmological probes. We provide a comprehensive survey of the resulting limits and prospects across all relevant channels, highlighting the central role of flavor physics in exploring the landscape of light dark matter.

    hep-ph4 citations
23. 23*

    Polarized and unpolarized synchrotron emission from dark matter in extragalactic targets

    Javier Reynoso-Cordova🇮🇹 · Catherine Gibson🇺🇸 · Stefano Profumo🇺🇸

    We compute 95% confidence-level upper limits on the dark matter annihilation cross section and decay rate from both total-intensity and polarized synchrotron emission in five extragalactic targets: M31, the Large Magellanic Cloud (LMC), the Draco and Sculptor dwarf spheroidal galaxies, and the Coma cluster. Using Planck maps at 30, 44, and 70 GHz, we solve the diffusion-loss equation for dark-matter-produced electrons and positrons numerically with DRAGON and integrate the resulting synchrotron emission along the line of sight with HERMES, computing both total-intensity and polarized-intensity maps for each target with target-specific magnetic-field, gas, and radiation-field environments. The 30 GHz channel yields the most stringent constraints in all cases, and limits on annihilation or decay into $e^{+}{e}^{-}$ are stronger than those for $b\bar{b}$ due to the harder injected spectrum. For most targets the total-intensity and polarized limits are broadly comparable; the LMC is an exception, where Faraday depolarization in the turbulent disk suppresses the polarized signal relative to total intensity, making total intensity the primary estimator. Our results are robust against the choice of flux estimator and coordinate uncertainty. This work demonstrates that microwave polarimetry provides a complementary and largely independent probe of dark matter synchrotron emission in extragalactic targets.

    ↳ astro-ph.GAastro-ph.COastro-ph.HEhep-ph0 citations
24. 24*

    Arithmetic Symmetry in Ideal Prouhet-Tarry-Escott Solutions

    Yu-Dai Tsai🇺🇸 · Junseok Lee🇯🇵 · Fuminobu Takahashi🇯🇵

    Motivated in part by anomaly cancellation for integral charge spectra in chiral gauge theory, we study the symmetric locus in the ideal degree-three Prouhet-Tarry-Escott problem. A symmetric integer solution is one whose entries are paired about a common center $c\in \frac{1}{2}\mathbb{Z}$. This symmetry reduces the problem to a sum-of-two-squares equation, $x^2+y^2=u^2+v^2$, in integer variables, subject to the appropriate parity conditions. Thus the problem is governed by representations as sums of two squares. For the full symmetric locus, let $N_{\mathrm{sym}}(H)$ denote the number of nontrivial symmetric integer solutions of height at most $H$, counted with unordered multiset conventions and summed over the admissible centers. Then \begin{align*} N_{\mathrm{sym}}(H) = \frac{4\log 2}{3\pi^2}H^3\log H+O(H^3). \end{align*} The logarithmic enhancement comes from the second moment of the sum-of-two-squares representation function. In particular, the symmetric locus is larger than one would expect from the naive $H^3$ degree-weighted box-counting scale alone. This asymptotic identifies a large arithmetically structured subfamily of the ideal degree-three solution space, and suggests that paired anomaly-free integral charge spectra reflect a fundamental number-theoretic structure.

    ↳ math.NThep-phhep-thmath-ph+10 citations
25. 25*

    Searching for axion dark matter conversion spectral lines in neutron star magnetospheres with FAST

    Sinuo Gao🇨🇳 · Chen Wang🇨🇳 · Maoyuan Liu🇨🇳

    The axion is a well-motivated dark matter candidate, which can convert into narrow radio spectral lines via the Primakoff effect in the strongly magnetized magnetospheres of neutron stars. This provides a novel astrophysical probe for axion searches that is complementary to laboratory experiments. Using FAST, the world's most sensitive single-dish radio telescope, we observed two X-ray dim isolated neutron stars (RXJ1605.3+3249 and RXJ1308.6+2127) within its sky coverage, which are predicted to yield the strongest axion-conversion spectral lines (ACL). Although no significant signal was detected at the 5 sigma confidence level, we establish new upper limits on the axion-photon coupling constant g_{a gamma gamma} less than or similar to 5 x 10^{-12} GeV^{-1} for axion masses ranging from 4.14 to 6.20 micro-eV corresponding to the 1.0-1.5 GHz observational band. This result constitutes the tightest constraint in this axion mass range among all existing studies employing the same ACL-based method.

    ↳ astro-ph.HEastro-ph.SRhep-ph1 citation

* 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.