HEP Phenomenology·hep-ph

Wed·Dec 4, 2024Wednesday·December 4, 2024

37 papers—22 primary·15 cross-listed·reconstructed*

01*
Constraints on the malaphoric $B_{3} - L_{2}$ model from di-lepton resonance searches at the LHC
Ben Allanach (Cambridge University)🇬🇧
We confront the malaphoric $B_{3} - L_{2}$ model with bounds coming from a search for resonances in the di-lepton channels at the 13~TeV LHC. In contrast to the original $B_{3} - L_{2}$ model, the $Z^{'}$ of the malaphoric $B_{3} - L_{2}$ model has sizeable couplings to the lighter two families; these originate from order unity kinetic mixing with the hypercharge gauge boson and ameliorate the fit to lepton flavour universality measurements in $B -$ meson decays. The $Z^{'}$ coupling to the first two families of quark means that the resulting constraints from resonant di-lepton searches are stronger. Nevertheless, we find that for $M_{Z^{'}} > 2.8$ TeV there remains a non-negligible region of allowed parameter space where the model significantly improves upon several Standard Model predictions for observables involving the $b \to s l^{+} l^{-}$ transition. We estimate that the 3000 fb $^{- 1}$ HL-LHC will extend this sensitivity to $M_{Z^{'}} = 4.2$ TeV.
hep-phhep-exEPJC(2025)·4 citations
02*
Deep-inelastic scattering with collider neutrinos at the LHC and beyond
Toni Mäkelä🇺🇸
Proton-proton collisions at the LHC generate high-intensity collimated beams of forward neutrinos up to TeV energies. Their recent observations and the initiation of a novel LHC neutrino program motivate investigations of this previously unexploited beam. The kinematic region for neutrino deep-inelastic scattering measurements at the LHC overlaps with that of the Electron-Ion Collider. The effect of the LHC $ν$ DIS data on parton distribution functions (PDFs) is assessed by generating projections for the Run 3 LHC experiments, and for select proposed detectors at the HL-LHC. Estimating their impact in global (n)PDF analyses reveals a significant reduction of PDF uncertainties, particularly for strange and valence quarks. Furthermore, the effect of neutrino flux uncertainties is examined by parametrizing the correlations between a broad selection of neutrino production predictions in forward hadron decays. This allows determination of the highest achievable precision for neutrino observations, and constraining physics within and beyond the Standard Model. This is demonstrated by setting bounds on effective theory operators, and discussing the prospects for an experimental confirmation of the enhanced strangeness scenario proposed to resolve the cosmic ray muon puzzle, using LHC data. Moreover, there is promise for a first measurement of neutrino tridents with a statistical significance exceeding 5 $σ$ .
hep-phActa Phys.Polon.Supp.(2025)·0 citations
03*
Multi-component secluded WIMP dark matter and Dirac neutrino masses with an extra Abelian gauge symmetry
Kimy Agudelo🇨🇴 · Diego Restrepo🇨🇴 · Andrés Rivera🇨🇴 · David Suarez🇨🇴
Scenarios for secluded WIMP dark matter models have been extensively studied in simplified versions. This paper shows a complete UV realization of a secluded WIMP dark matter model with an extra Abelian gauge symmetry that includes two-component dark matter candidates, where the dark matter conversion process plays a significant role in determining the relic density in the Universe. The model contains two new unstable mediators: a dark Higgs and a dark photon. It generates Dirac neutrino masses and can be tested in future direct detection experiments of dark matter. The model is also compatible with cosmological and theoretical constraints, including the branching ratio of Standard model particles into invisible, Big Bang nucleosynthesis restrictions, and the number of relativistic degrees of freedom in the early Universe, even without kinetic mixing.
hep-phPRD(2025)·5 citations
04*
Electromagnetic interactions in elastic neutrino-nucleon scattering
Konstantin A. Kouzakov🇷🇺 · Fedor M. Lazarev🇷🇺 · Alexander I. Studenikin🇷🇺
A thorough account of electromagnetic interactions of massive Dirac neutrinos as well as their spin-flavor state in the theoretical formulation of elastic neutrino-nucleon scattering is given. The formalism of neutrino charge, magnetic, electric, and anapole form factors defined as matrices in the mass basis is employed under the assumption of three-neutrino mixing. The flavor and spin change of neutrinos propagating from the source to the detector is taken into account in the form of a spin-flavor density matrix of the neutrino arriving at the detector. The potential effects of the neutrino charge radii, magnetic moments, and spin polarization in the neutrino-nucleon scattering experiments are outlined.
hep-phnucl-thPRD(2025)·7 citations
05*
Remarks on strong phase shifts in weak nonleptonic baryon decays
Hong-Jian Wang🇨🇳 · Pei-Rong Li🇨🇳 · Xiao-Rui Lyu🇨🇳 · Jusak Tandean🇨🇳 · Hai-Bo Li🇨🇳
A sizable strong-interaction phase shift in weak two-body nonleptonic baryon decay would enhance the possibility of discovering charge-conjugation parity ( $C P$ ) violation in the baryon sector, which might help in the quest for understanding the matter-antimatter asymmetry in the universe. Over the past 60 years, empirical analyses involving different types of instruments, including fixed-target experiments and $e^{+} e^{-}$ colliders, have indicated that the phase shifts in nonleptonic hyperon decays are relatively small, below order ten degrees in size. A large phase shift, however, has been observed by BESIII in the decay of a charmed baryon into a hyperon and kaon, $Λ_{c}^{+} \to Ξ^{0} K^{+}$ . In various experimental and theoretical studies on hyperon, charmed-baryon, and bottomed-baryon decays, different conventions have been adopted for defining the strong phases. It is important to be aware of this situation when obtaining global averages from different measurements and applying the results to future investigations on $C P$ violation among baryons. This paper gives an overview of the conventions employed in the literature for the strong phases and suggests a unified parameterization form applicable to the different alternatives. Numerical results under the unified parameterization form are also provided, which can serve as useful inputs to further pursuits of baryon $C P$ violation.
hep-phhep-exSci.Bull.(2025)·7 citations
06*
96 GeV Scalar Boson in the 2HDM with U(1)_H Gauge Symmetry
Seungwon Baek🇰🇷 · P. Ko🇰🇷 · Yuji Omura🇯🇵 · Chaehyun Yu🇰🇷
In this paper, we study two Higgs doublet models with gauged U(1)_H symmetry, motivated by the excesses around 96 GeV reported by the CMS collaboration in the searches for light resonances decaying to two photons and two \tau's. In this model, one Higgs doublet field is charged under the U(1)_H symmetry to avoid tree-level flavor changing neutral currents. The extra gauge symmetry requires extra chiral fermions, to satisfy the anomaly-free conditions. We analyze the signals of the light resonances, taking into account the contribution of the extra fermions, and discuss the consistency with the experimental results in this model.
hep-phhep-exEPJC(2025)·10 citations
07*
Electromagnetic polarizabilities of the spin- $\frac{1}{2}$ singly heavy baryons in heavy baryon chiral perturbation theory
Yan-Ke Chen🇨🇳 · Liang-Zhen Wen🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳
We calculate the electromagnetic polarizabilities of the spin- $\frac{1}{2}$ singly heavy baryons in the heavy baryon chiral perturbation theory up to $O (p^{3})$ . We estimate the low-energy constants using the magnetic moments of singly charmed baryons from lattice QCD simulations and the experimental decay widths of $Σ_{c}$ and $Σ_{c}^{*}$ . Our results indicate that the long-range chiral corrections make significant contributions to the polarizabilities. Additionally, the magnetic dipole transitions $B_{6}^{*} \to B_{6} + γ$ also provide large contribution to the magnetic polarizabilities.
hep-phhep-exhep-latPRD(2025)·6 citations
08*
Analysis of anomalous $H γ γ$ coupling in light-by-light collision at future muon collider
Serdar Spor🇹🇷 · Emre Gurkanli🇹🇷
In this study, the process $γ γ \to γ γ$ is investigated to establish constraints on anomalous Higgs boson couplings at $H γ γ$ vertex within the framework of the Standard Model Effective Field Theory (SMEFT). The study is performed for a future muon collider operating at CoM energies of 10 and 30 TeV with integrated luminosities of 10 and 90 ab $^{- 1}$ , respectively, where the incoming photons are modeled using the Weizsäcker-Williams approximation. Signal and background events are simulated using MadGraph, with the SMEFT Lagrangian implemented via FeynRules and UFO frameworks. Parton showering is evaluated with PYTHIA 8, and detector effects are accounted for using Delphes. Limits on the Wilson coefficients $c ˉ_{γ}$ and $c ~_{γ}$ of the dim-6 operators without and with systematic uncertainties of 5% and 10% are reported at the 95% confidence level, demonstrating the potential of a high-energy muon collider to provide precise constraints on these couplings and presenting a significant improvement over experimental and related phenomenological results.
hep-phNPB(2026)·3 citations
09*
Deformed AdS/QCD, mesonic mass spectra, and DCE: Still a margin for heavier resonances
Roldao da Rocha🇧🇷 · Pedro H. O. Silva🇧🇷
The mass spectra of light-flavor mesons are analyzed in a deformed AdS/QCD soft-wall model, driven by four distinct anomalous 5-dimensional mass corrections of the scalar field, coupled to Einstein--Hilbert gravity, from the QCD running coupling. Using the differential configurational entropy (DCE) underlying the families of pseudoscalar, axial-vector, scalar, and vector mesons, the mass spectra of heavier meson resonances with radial quantum numbers beyond the ones already in the summary table of Particle Data Group (PDG) are then estimated. This protocol merges AdS/QCD and experimental data in PDG through Regge-like trajectories. Some of the estimated meson resonances may be identified as further candidates omitted from the summary table in PDG.
hep-phhep-thPRD(2024)·4 citations
10*
Non-perturbative constraints on perturbation theory at finite temperature
Peter Lowdon🇩🇪 · Owe Philipsen🇩🇪
It has long been understood that the inclusion of temperature in the perturbative treatment of quantum field theories leads to complications that are not present at zero temperature. In these proceedings we report on the non-perturbative obstructions that arise, and how these lead to deviations in the predictions of lattice scalar correlation functions in massive $ϕ^{4}$ theory. Using the known non-perturbative spectral constraints satisfied by finite-temperature correlation functions we outline why the presence of distinct particle-like excitations could provide a resolution to these issues.
hep-phhep-lathep-thnucl-thJ.Subatomic Part.Cosmol.(2025)·1 citation
11*
Gravitational Waves as a Probe of Particle Dark Matter
Sulagna Bhattacharya (Tata Inst., Mumbai)🇮🇳
Galactic dark matter (DM) particles, having non-gravitational interactions with nucleons, can interact with stellar constituents and eventually become captured within stars. Over the lifetime of the celestial body, these non-annihilating, heavy DM particles may accumulate and eventually form a comparable stellar mass black hole (BH), referred to as a Transmuted Black Hole (TBH). We investigate how current gravitational wave (GW) experiments could detect such particle DM through the presence of low-mass TBHs, which cannot form via standard stellar evolution. Different stellar objects (compact and non-compact) provide laboratories across DM-nucleon interaction regimes, offering insight into DM's mass and its non-gravitational properties.
hep-phastro-ph.COSpringer Proc.Phys.(2026)·3 citations
12*
Excited $Ω$ hyperon in charmful $Ω_{b}$ weak decays
Kai-Lei Wang🇨🇳 · Juan Wang🇨🇳 · Yu-Kuo Hsiao🇨🇳 · Xian-Hui Zhong🇨🇳
We investigate the sextet $b$ -baryon decay processes $Ω_{b} \to J / ψ Ω^{(*)}$ ,where $Ω^{*}$ represents the $1 P$ -, $1 D$ - and $2 S$ -wave excited $Ω$ hyperons in the spectroscopy. Using the constituent quark model, we obtain $B (Ω_{b} \to J / ψ Ω) = 8.8 \times 1 0^{- 4}$ , which agrees with the previous studies to the order of magnitude. By identifying $Ω (2012)$ as $Ω (1^{2} P_{3/ 2^{-}})$ , $B (Ω_{b} \to J / ψ Ω (2012)) = 1.1 \times 1 0^{- 3}$ can be similarly significant. Additionally, $Ω (1^{2} D_{5/ 2^{+}})$ and $Ω (1^{4} D_{3/ 2^{+}}, 1^{4} D_{5/ 2^{+}})$ states exhibit production rates of 0.5, and (0.6, 0.8), respectively, relative to their ground-state counterpart. Notably, our findings suggest that $B (Ω_{b} \to J / ψ Ω (2^{2} S_{1/ 2^{+}}, 2^{4} S_{3/ 2^{+}}))$ are as large as $(4.5, 20) \times 1 0^{- 4}$ , making them accessible to experiments at LHCb.
hep-phPRD(2025)·6 citations
13*
Separation of left-handed and anomalous right-handed vector operators contributions into the Wtb vertex for single and double resonant top quark production processes using a neural network
E. Abasov🇷🇺 · E. Boos🇷🇺 · V. Bunichev🇷🇺 · L. Dudko🇷🇺 · D. Gorin🇷🇺 · A. Markina🇷🇺 · M. Perfilov🇷🇺 · O. Vasilevskii🇷🇺 · P. Volkov🇷🇺 · G. Vorotnikov🇷🇺 · A. Zaborenko🇷🇺
The paper describes the application of deep neural networks for the searchdeviations from the Standard Model predictions at the Wtb vertex in the processes of single and double resonant top quark production with identical final state tWb. Monte-Carlo events preliminary classified by first level neural network as corresponding to single or double resonant top quark production are analyzed by two second level neural networks if there is a possible contribution of the anomalous right-handed vector operator into Wtb vertex or events are corresponded to the Standard Model. The second level neural networks are different for single and double resonant classes. The classes depend differently on anomalous contribution and such splitting leads to better sensitivity. The developed statistical model is used to set constraints on the anomalous right-handed vector operator at the Wtb vertex in different regions of phase space. It is demonstrated that the proposed method allows to increase the efficiency of a search for the anomalous contributions to the Wtb vertex.
hep-phPhys.Part.Nucl.(2025)·1 citation
14*
Determination of the Strong Coupling Constant $α_{s}$ from Inclusive Semi-leptonic $B$ Meson Decays
Yuzhi Che🇨🇳 · Long Chen🇨🇳 · Jinfei Wu🇨🇳 · Xinchou Lou🇨🇳 · Xiang Chen🇨🇭 · Xin Guan🇺🇸 · Yan-Qing Ma🇨🇳 · Manqi Ruan🇨🇳
We demonstrate the feasibility of determining the strong coupling constant, $α_{s}$ , from the inclusive semileptonic decay width of $B$ mesons. We express the semileptonic $B$ decay width as a function of $α_{s} (5 GeV)$ , the Cabibbo-Kobayashi-Maskawa matrix element $∣ V_{c b} ∣$ , $b$ - and $c$ -quark masses in the $MS$ scheme. We fit $α_{s} (5 GeV)$ to current world averages of the $B^{\pm}$ and $B^{0}$ semileptonic decay widths. This yields $α_{s} (5 GeV) = 0.245 \pm 0.009$ , corresponding to a 5-flavor extrapolation of $α_{s} (m_{Z}) = 0.1266 \pm 0.0023$ . The primary uncertainty contributions arise from the uncertainty on the perturbative expansion and the value of $∣ V_{c b} ∣$ . Future advancements including higher-order perturbative calculations, and precise measurements of $∣ V_{c b} ∣$ and $B$ decay widths from upcoming $B$ and $Z$ factories, could enable this method to determine $α_{s} (m_{Z})$ with a competitive precision of $Δ α_{s} (m_{Z}) \sim 0.0018$ . This precision is comparable to the current accuracy of $α_{s} (m_{Z})$ measurements from $τ$ -lepton decays, which is regarded as the most precise experimental approach.
hep-phhep-exPRD(2025)·1 citation
15*
Particle production in the toy world: multiplicity distribution and entropy
Eugene Levin (Tel Aviv U.)🇮🇱
In this paper we found the multiplicity distribution of the produced dipoles in the final state for dipole-dipole scattering in the zero dimension toy models. This distribution shows the great differences from the distributions of partons in the wave function of the projectile. However, in spite of this difference the entropy of the produced dipoles turns out to be the same as the entropy of the dipoles in the wave function. This fact is not surprising since in the parton approach only dipoles in the hadron wave function which can be produced at $t = + \infty$ and measured by the detectors. We can also confirm the result of Kharzeev and Levin that this entropy is equal to $S_{E} = ln (x G (x))$ , where we denote by $x G$ the mean multiplicity of the dipoles in the deep inelastic scattering. The evolution equations for $σ_{n}$ are derived.
hep-phPRD(2025)·11 citations
16*
Exploring Dark Photon Production and Kinetic Mixing Constraints in Heavy-Ion Collisions
Adrian William Romero Jorge🇩🇪 · Elena Bratkovskaya🇩🇪 · Taesoo Song🇩🇪 · Laura Sagunski🇩🇪
Vector $U$ -bosons, often referred to as 'dark photons', are potential candidates for mediating dark matter interactions. In this study, we outline a procedure to derive theoretical constraints on the upper bound of the kinetic mixing parameter $ϵ^{2} (M_{U})$ using dilepton data from heavy-ion from SIS to RHIC energies. The analysis is based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport model, which successfully reproduces the measured dilepton spectra in $p + p$ , $p + A$ , and $A + A$ collisions. Besides the dilepton channels resulting from interactions and decays of Standard Model particles (such as mesons and baryons), we extend the PHSD approach to include the decay of hypothetical $U$ -bosons into dileptons, $U \to e^{+} e^{-}$ . The production of these $U$ -bosons occurs via Dalitz decays of pions, $η$ -mesons, $ω$ -mesons, Delta resonances, as well as from the decays of vector mesons and $K^{+}$ mesons. This analysis provides an upper limit on $ϵ^{2} (M_{U})$ and offers insights into the accuracy required for future experimental searches for dark photons through dilepton experiments.
hep-phAstron.Nachr.(2025)·2 citations
17*
Bounds on Axions-Like Particles Shining in the Ultra-Violet
Elisa Todarello🇬🇧 · Marco Regis🇮🇹
Axion-like particles (ALPs) can decay into two photons with a rest-frame frequency given by half of the ALP mass. This implies that ultra-violet searches can be used to investigate ALPs in the multi-eV mass range. We use archival data from the Hubble Space Telescope between 110 and 170 nm to constrain ALPs with mass between 14.4-22.2 eV. We consider observations of a set of dwarf spheroidal galaxies and galaxy clusters and assume the ALP density in these objects to follow their dark matter density. The derived limit on the ALP-photon coupling $g_{aγ}$ excludes values above $1 0^{- 12} GeV^{- 1}$ over the whole mass range and surpasses previous limits by over one order of magnitude.
hep-phastro-ph.COJCAP(2025)·18 citations
18*
Anatomy of singlet-doublet dark matter relic: annihilation, co-annihilation, co-scattering, and freeze-in
Partha Kumar Paul🇮🇳 · Sujit Kumar Sahoo🇮🇳 · Narendra Sahu🇮🇳
The singlet-doublet vector-like fermion dark matter model has been extensively studied in the literature over the past decade. An important parameter in this model is the singlet-doublet mixing angle ( $sin θ$ ). All the previous studies have primarily focused on annihilation and co-annihilation processes for obtaining the correct dark matter relic density, assuming that the singlet and doublet components decouple at the same epoch. In this work, we demonstrate that this assumption holds only for larger mixing angles with a dependency on the mass of the dark matter. However, it badly fails for the mixing angle $sin θ < 0.05$ . We present a systematic study of the parameter space of the singlet-doublet dark matter relic, incorporating annihilation, co-annihilation, and, for the first time, co-scattering processes. Additionally, non-thermal productions via the freeze-in and SuperWIMP mechanism are also explored. We found that due to the inclusion of co-scattering processes, the correct relic density parameter space is shifted towards the detection sensitivity range of the LHC and MATHUSLA via displaced vertex signatures.
hep-phastro-ph.COhep-exJCAP(2025)·13 citations
19*
Heavy quark mass effects in the Energy-Energy Correlation in the back-to-back region
Ugo Giuseppe Aglietti🇮🇹 · Giancarlo Ferrera🇮🇹
We consider heavy quark mass ( $m$ ) effects in the Energy-Energy Correlation function in $e^{+} e^{-} \to ha d r o n s$ at high energy $Q$ , in the back-to-back (two-jet) region. In the ultra-relativistic limit, $Q ≫ m$ , the QCD Sudakov form factor $S (b)$ in impact parameter ( $b$ -)space reads: \begin{eqnarray} \log S(b) &=& - \int_{m^2}^{Q^2} \frac{dk^2}{k^2} \left\{ \log\left(\frac{Q^2}{k^2}\right) A[\alpha_S(k^2)] + B[\alpha_S(k^2)]\right\} [1-J_0(b k)] \nonumber\\ && - \int_0^{m^2} \frac{dk^2}{k^2} \left\{ \log\left(\frac{Q^2}{m^2}\right) A[\alpha_S(k^2)] + D[\alpha_S(k^2)] \right\} [1-J_0(b k)]. \nonumber \end{eqnarray} The double-log function $A (α_{S})$ describes the effects of soft gluons, quasi-collinear to the original quark-antiquark pair, while the single-log functions $B (α_{S})$ and $D (α_{S})$ describe hard collinear radiation and soft radiation not log-collinearly enhanced, respectively. The usual logarithmic expansion of the low transverse momenta contribution to the form factor ( $k^{2} < m^{2}$ ) involves two new function series. An explicit evaluation of the heavy quark form factor at Next-to-Next-to-Leading Logarithmic accuracy is presented. The relation of our results with the well-known (classical) dead-cone effect in gauge theories is analyzed. At Next-to-Leading Logarithmic (NLL) accuracy, an improved formula for the dead cone is proposed; the soft term produces an increase of the dead-cone opening angle of a factor $e ≃ 1.64872$ . However, beyond NLL, a physical interpretation of this kind breaks down. The generalization of the above formula to the resummation of shape variables in $e^{+} e^{-}$ annihilation, or to the resummation of the transverse momentum distributions in hadron collisions, is also briefly discussed.
hep-phEPJC(2025)·15 citations
20*
Gravitational waves from supercooled phase transitions in conformal Majoron models of neutrino mass
João Gonçalves🇵🇹 · Danny Marfatia🇺🇸 · António P. Morais🇵🇹 · Roman Pasechnik🇸🇪
We study supercooled first-order phase transitions above the QCD scale in a wide class of conformal Majoron-like U(1)' models that explain the totality of active neutrino oscillation data and produce a detectable stochastic gravitational wave background (SGWB) at LIGO, LISA and ET. We place constraints on the U(1)' breaking scale and gauge coupling using current LIGO-Virgo-Kagra data. We find that strong supercooling can be ruled out in large regions of parameter space if a SGWB is not detected by these experiments. A null signal at LIGO and ET will disfavor a type-I seesaw scale above $1 0^{14}$ GeV, while a positive signal is a signature of heavy right-handed neutrinos. On the other hand, LISA will be sensitive to seesaw scales as low as a TeV, and could detect a SGWB even if the right-handed neutrinos are decoupled.
hep-phastro-ph.COhep-exJHEP(2025)·14 citations
21*
Holographic Energy Correlators for Soft Walls
Csaba Csáki🇺🇸 · Steven Ferrante🇺🇸 · Ameen Ismail🇺🇸
We calculate energy correlators in a general holographic model of confinement, involving an asymptotically anti-de Sitter (AdS) warped extra dimension. Building on a recent computation in a minimal hard-wall model of confinement, we show that the shockwave method for efficiently computing energy correlators in AdS generalizes to an arbitrary warped geometry. This is possible because exact, linear shockwave solutions to the 5D field equations exist in any warped background. We apply our formalism to compute the two-point energy correlator for two simple models of confinement with interesting infrared spectra -- one with a gapped continuum spectrum and one with linear Regge trajectories. The results differ from the simple hard-wall model and from each other, demonstrating that the details of the confining dynamics affect the shape of the energy correlator observables.
hep-phhep-thJHEP(2025)·12 citations
22*
Theory of neutrino slow flavor evolution. Part I. Homogeneous medium
Damiano F. G. Fiorillo🇩🇪 · Georg G. Raffelt🇩🇪
Dense neutrino gases can exhibit collective flavor instabilities, triggering large flavor conversions that are driven primarily by neutrino-neutrino refraction. One broadly distinguishes between fast instabilities that exist in the limit of vanishing neutrino masses, and slow ones, that require neutrino mass splittings. In a related series of papers, we have shown that fast instabilities result from the resonant growth of flavor waves, in the same way as turbulent electric fields in an unstable plasma. Here we extend this framework to slow instabilities, focusing on the simplest case of an infinitely homogeneous medium with axisymmetric neutrino distribution. The relevant length and time scales are defined by three parameters: the vacuum oscillation frequency $ω_{E} = δ m^{2} /2 E$ , the scale of neutrino-neutrino refraction energy $μ = 2 G_{F} (n_{ν} + n_{ν})$ , and the ratio between lepton and particle number $ϵ = (n_{ν} - n_{ν}) / (n_{ν} + n_{ν})$ . We distinguish between two very different regimes: (i) For $ω_{E} ≪ μ ϵ^{2}$ , instabilities occur at small spatial scales of order $(μ ϵ)^{- 1}$ with a time scale of order $ϵ ω_{E}^{- 1}$ . This novel branch of slow instability arises from resonant interactions with neutrinos moving along the axis of symmetry. (ii) For $μ ϵ^{2} ≪ ω_{E} ≪ μ$ , the instability is strongly non-resonant, with typical time and length scales of order $1/ ω_{E} μ$ . Unstable modes interact with all neutrino directions at once, recovering the characteristic scaling of the traditional studies of slow instabilities. In the inner regions of supernovae and neutron-star mergers, the first regime may be more likely to appear, meaning that slow instabilities in this region may have an entirely different character than usually envisaged.
hep-phastro-ph.HEJHEP(2025)·30 citations
23*
Banks-Zaks Stabilisation of Non-SUSY Strings
Steven Abel🇬🇧 · Ivano Basile🇩🇪 · Viktor Matyas🇬🇧
It appears to be difficult within string theory to obtain genuine scale separation between spacetime and the internal sector. In this paper, we propose a novel mechanism for scale-separated vacua which hinges on stringy effects that are invisible at the level of effective field theory. We show that (meta)stable vacua can form if a super no-scale one-loop potential combines with generic two-loop contributions to the vacuum energy, in a manner analogous to Banks-Zaks fixed points. Weak string coupling and scale separation arise from the accidental smallness of the one-loop term, which receives contributions only from massive states, relative to the two-loop term. We provide a proof of concept of this mechanism in explicit non-supersymmetric heterotic toroidal orbifolds by balancing the complete one-loop contribution against the estimated two-loop term and numerically minimizing the resulting effective potential in a restricted sector of moduli space. We note that this mechanism is generically possible within any fundamental theory that has a one-loop energy that gets contributions only from massive modes.
↳ hep-thhep-phJHEP(2025)·11 citations
24*
Regulated chiral gauge theory and the strong CP problem
David B. Kaplan🇺🇸 · Srimoyee Sen🇺🇸
Four-dimensional chiral gauge theory can be formulated as the boundary theory on a five-dimensional manifold in a manner that may be realized on a finite lattice. There are interesting features of these theories which defy a purely four-dimensional conception of universality. We find that QCD when embedded in a chiral gauge theory (the Standard Model) and regulated this way can simultaneously avoid both the $U (1)_{A}$ problem and the strong $C P$ problem, with a central role played by fermion zeromodes localized far away in the fifth dimension. In this way it differs from conventional lattice QCD formulated as a stand-alone theory, universality being violated by inaccessible light modes in the five-dimensional bulk. Our analysis builds on recent work by others that highlights the role of global $U (1)$ symmetries in five dimensional formulations of four-dimensional chiral gauge theories, and the generic appearance of fermion zeromodes in the bulk.
↳ hep-lathep-phhep-thnucl-thPRD(2026)·12 citations
25*
Quantum and classical dynamics of neutron in a magnetic field
A. Bogomyagkov🇷🇺 · V. Druzhinin🇷🇺 · E. Levichev🇷🇺 · A. Milstein🇷🇺 · I. Okunev🇷🇺 · S. Taskaev🇷🇺
The paper presents solution of quantum problem of neutron propagation in the magnetic field with multipole field expansion. Rigorous solution of the Pauli equation for neutron reveals existence of two solutions, finite and infinite, for any multipole configuration. As an example, we present detailed study of neutron motion in quadrupole and sextupole magnets. Our predictions agree with the results of Stern-Gerlach experiment for neutrons. To verify existence of finite and infinite motion, we discuss an experiment which could be performed in the Budker Insitute of Nuclear Physics using existing equipment. We conclude with considerations of neutron storage ring with straight section and discrete magnets focusing the beam.
↳ hep-exhep-phphysics.acc-phNPB(2025)·0 citations
26*
Pulsar Polarization Array Limits on Ultralight Axion-like Dark Matter
Xiao Xue🇪🇸 · Shi Dai🇦🇺 · Hoang Nhan Luu🇪🇸 · Tao Liu🇨🇳 · Jing Ren🇨🇳 · Jing Shu🇨🇳 · Yue Zhao🇺🇸 · Andrew Zic🇦🇺 · N. D. Ramesh Bhat🇦🇺 · Zu-Cheng Chen🇨🇳 · Yi Feng🇨🇳 · George Hobbs🇦🇺 and 11 other authors
We conduct the first-ever Pulsar Polarization Array (PPA) analysis to detect the ultralight Axion-Like Dark Matter (ALDM) using the polarization data of 22 millisecond pulsars from the third data release of Parkes Pulsar Timing Array. As one of the major dark matter candidates, the ultralight ALDM exhibits a pronounced wave nature on astronomical scales and offers a promising solution to small-scale structure issues within local galaxies. While the linearly polarized pulsar light travels through the ALDM galactic halo, its position angle (PA) can be subject to an oscillation induced by the ALDM Chern-Simons coupling with electromagnetic field. The PPA is thus especially suited for detecting the ultralight ALDM by correlating polarization data across the arrayed pulsars. To accomplish this task, we develop an advanced Bayesian analysis framework that allows us to construct pulsar PA residual time series, model noise contributions properly and search for pulsar cross-correlations. We find that for an ALDM density of $ρ_{0} = 0.4 GeV / cm^{3}$ , the Parkes PPA offers the best global limits on the ALDM Chern-Simons coupling, namely $≲ 1 0^{- 13.5} - 1 0^{- 12.2} GeV^{- 1}$ , for the mass range of $1 0^{- 22} - 1 0^{- 21} eV$ . The crucial role of pulsar cross-correlation in recognizing the nature of the derived limits is also highlighted.
↳ astro-ph.HEastro-ph.COastro-ph.IMhep-phPRL(2026)·27 citations
27*
The mass of the gluino-glue bound state in large- $N$ $N = 1$ Supersymmetric Yang-Mills theory
Claudio Bonanno🇪🇸 · Margarita García Pérez🇪🇸 · Antonio González-Arroyo🇪🇸 · Ken-Ichi Ishikawa🇯🇵 · Masanori Okawa🇯🇵
We provide a first-principles non-perturbative determination of the mass of the lightest gluino-gluon bound state (gluino-glue) in large- $N$ $N = 1$ Supersymmetric Yang--Mills theory by means of numerical Monte Carlo simulations of the lattice-discretized theory, and exploiting large- $N$ twisted volume reduction. Our large- $N$ determination is consistent with naive extrapolation of previously-known $SU (2)$ and $SU (3)$ results.
↳ hep-lathep-phJHEP(2025)·9 citations
28*
Lefschetz thimble-inspired weight regularizations for complex Langevin simulations
Kirill Boguslavski🇦🇹 · Paul Hotzy🇦🇹 · David I. Müller🇦🇹
Complex Langevin (CL) is a computational method to circumvent the numerical sign problem with applications in finite-density quantum chromodynamics and the real-time dynamics of quantum field theories. It has long been known that, depending on the simulated system, CL does not always converge correctly. In this work, we provide numerical evidence that the success or failure of the complex Langevin method is deeply tied to the Lefschetz thimble structure of the simulated system. This is demonstrated by constructing weight function regularizations that deform the thimbles of systems with compact domains. Our results indicate that CL converges correctly when the regularized system exhibits a single relevant compact thimble. We introduce a bias correction to retrieve the values of the original theory for parameter sets where a direct complex Langevin approach fails. The effectiveness of this method is illustrated using several toy models, including the cosine model and the SU(2) and SU(3) Polyakov chains. Finally, we discuss the opportunities and limitations of this regularization approach for lattice field theories.
↳ hep-lathep-phSciPost Phys.(2025)·13 citations
29*
Constraint on initial conditions of one-dimensional expanding fluids from nonlinear causality
Tau Hoshino🇯🇵 · Tetsufumi Hirano🇯🇵
The initial conditions of one-dimensional expanding viscous fluids in relativistic heavy-ion collisions are scrutinized in terms of nonlinear causality of the relativistic hydrodynamic equations. Conventionally, it is believed that the matter generated in relativistic heavy-ion collisions starts to behave as a fluid all at once at some initial time. However, it is by no means trivial how soon after the first contact of two high-energy nuclei the fluid picture can be applied. It is demonstrated that one-dimensional expanding viscous fluids violate the necessary and the sufficient conditions of nonlinear causality at large departures from local equilibrium. We therefore quantify the inverse Reynolds number to justify the hydrodynamic description to be valid. The initial conditions are strictly constrained not to violate the causality conditions during the time evolution. With the help of the transverse energies per rapidity measured at RHIC and LHC, we obtain the minimum initial proper time and the maximum energy density allowed by nonlinear causality. This analysis strongly suggests that the initial stage of relativistic heavy-ion collisions needs to be described by a non-equilibrium description other than the framework of relativistic dissipative hydrodynamics.
↳ nucl-thhep-phnucl-exPRC(2025)·4 citations
30*
Formulation and Proof of the Gravitational Entropy Bound
Artem Averin🇩🇪
We provide a formulation and proof of the gravitational entropy bound. We use a recently given framework which expresses the measurable quantities of a quantum theory as a weighted sum over paths in the theory's phase space. If this framework is applied to a field theory on a spacetime foliated by a hypersurface $Σ,$ the choice of a codimension-2 surface $B$ without boundary contained in $Σ$ specifies a submanifold in the phase space. We show here that this submanifold is naturally restricted to obey an entropy bound if the field theory is diffeomorphism-invariant. We prove this restriction to arise by considering the quantum-mechanical sum of paths in phase space and exploiting the interplay of the commutativity of the sum with diffeomorphism-invariance. The formulation of the entropy bound, which we state and derive in detail, involves a functional $K$ on the submanifold associated to $B .$ We give an explicit construction of $K$ in terms of the Lagrangian. The gravitational entropy bound then states: For any real $\frac{λ}{ℏ},$ consider the set of states where $K$ takes a value not bigger than $λ$ and let $V$ denote the phase space volume of this set. One has then $ln (V) \leq \frac{λ}{ℏ} .$ Especially, we show for the Einstein-Hilbert Lagrangian in any dimension with cosmological constant and arbitrary minimally coupled matter, one has $K = \frac{A}{4 G} .$ Hereby, $A$ denotes the area of $B$ in a particular state.
↳ hep-thgr-qchep-phJHEP(2025)·3 citations
31*
Study of primordial non-Gaussianity $f_{NL}$ and $g_{NL}$ with the cross-correlations between the scalar-induced gravitational waves and the cosmic microwave background
Zhi-Chao Zhao🇨🇳 · Sai Wang🇨🇳 · Jun-Peng Li🇨🇳 · Kazunori Kohri🇯🇵
The stochastic gravitational-wave background originating from cosmic sources contains vital information about the early universe. In this work, we comprehensively study the cross-correlations between the energy-density anisotropies in scalar-induced gravitational waves (SIGWs) and the temperature anisotropies and polarization in the cosmic microwave background (CMB). In our analysis of the angular power spectra for these cross-correlations, we consider all contributions of the local-type primordial non-Gaussianity $f_{NL}$ and $g_{NL}$ that can lead to large anisotropies. We show that the angular power spectra are highly sensitive to primordial non-Gaussianity. Furthermore, we project the sensitivity of future gravitational-wave detectors to detect such signals and, consequently, measure the primordial non-Gaussianity.
↳ astro-ph.COgr-qchep-phEPJC(2025)·8 citations
32*
Constraints on the Dirac spectrum from chiral symmetry restoration and the fate of $U (1)_{A}$ symmetry
Matteo Giordano🇭🇺
I discuss chiral symmetry restoration in the chiral limit $m \to 0$ of QCD with two light quark flavours of mass $m$ , focussing on its consequences for scalar and pseudoscalar susceptibilities, and on the resulting constraints on the Dirac spectrum. I show that $U (1)_{A}$ symmetry remains broken in the $SU (2)_{A}$ symmetric phase if the spectral density $ρ (λ; m)$ develops a singular near-zero peak, tending to $O (m^{4}) / λ$ in the chiral limit. Moreover, $SU (2)_{A}$ restoration requires that the number of modes in the peak be proportional to the topological susceptibility, indicating that such a peak must be of topological origin.
↳ hep-latcond-mat.dis-nnhep-phhep-thPoS(2025)·4 citations
33*
Testing inflation on all scales: a case study with $α$ -attractors
Laura Iacconi🇬🇧 · Michael Bacchi🇬🇧 · Luiz Filipe Guimarães🇧🇷 · Felipe T. Falciano🇧🇷
A plethora of inflationary models can produce interesting small-scale phenomenology, such as enhanced scalar fluctuations leading to primordial black hole (PBH) production and large scalar-induced GW. Nevertheless, good models must simultaneously explain current observations on all scales. In this work, we showcase our methodology to establish the small-scale phenomenology of inflationary models on firm grounds. We consider the case of hybrid $α$ -attractors, and focus on a reduced parameter space featuring the two potential parameters which roughly determine the position of the peak in the scalar power spectrum, $P_{ζ}$ , and its amplitude. We first constrain the parameter space by comparing the large-scale predictions for $P_{ζ}$ with current CMB anisotropies measurements and upper limits on $μ$ -distortions. We take into account uncertainties due to the reheating phase, and observe that the parameter-space area compatible with large-scale constraints shrinks for extended reheating stages. We then move to smaller scales, where we find that non-Gaussianity at peak scales is of the local type and has amplitude $f_{NL} \sim O (0.1)$ . This ensures that non-linear effects are subdominant, motivating us to employ the tree-level $P_{ζ}$ to compute the abundance of PBHs and the spectrum of induced GWs for models consistent with large-scale tests. The former allows us to further constrain the parameter space, by excluding models which over-produce PBHs. We find that a subset of viable models can lead to significant production of PBHs, and a fraction of these is within reach for LISA, having a signal-to-noise ratio larger than that of astrophysical foregrounds. Our first-of-its-kind study systematically combines tests at different scales, and exploits the synergy between cosmological observations and theoretical consistency requirements.
↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·14 citations
34*
Soft QCD Physics at the LHC: highlights and opportunities
Peter Christiansen🇸🇪 · Pierre Van Mechelen🇧🇪
The Large Hadron Collider (LHC) at CERN in Switzerland became operational in 2009 and has since then produced a plethora of results for proton-proton (pp) collisions. This short review covers results that relates to soft QCD focusing on non-diffractive physics at mid-rapidity. Most of the presented results comes from transverse momentum ( $p_{T}$ ) spectra and related/derived observables such as multiplicity, $⟨ p_{T} ⟩$ and ratios, but also the observed ``ridge'' and the questions of quark-gluon plasma in pp collisions will be discussed. The goal of the review is on one hand to introduce the topics and provide references for scientists joining the LHC program while at the same time highlighting what we consider the most interesting results and open questions to inspire novel measurements.
↳ hep-exhep-phnucl-exnucl-thAnn.Rev.Nucl.Part.Sci.(2025)·7 citations
35*
Effective Field Theory and In-In Correlators
Daniel Green🇺🇸 · Guanhao Sun🇺🇸
The predictions of inflation are usually defined in terms of equal time in-in correlation functions in an accelerating cosmological background. These same observables exist for quantum field theory in other spacetimes, including flat space. In this paper, we will explore how the Wilsonian renormalization group (RG) and effective field theory (EFT) apply to these observables in both flat and de Sitter space. Specifically, we show that matching the short- and long-distance calculations requires additional terms localized at the time of the measurement that are not captured by the effective action of the EFT. These additional terms only correct the local and semi-local terms in the EFT correlators. In flat space, we give an explicit demonstration by matching in-in correlators of light scalars interacting with a heavy field with the EFT result. We then show how these additional terms arise generically via exact RG. We also compare these explicit results in flat space with the corresponding theory in de Sitter and show that the local terms typically redshift away. Our results are closely related to momentum space entanglement that arises from tracing over short-wavelength modes.
↳ hep-thastro-ph.COhep-phJHEP(2025)·19 citations
36*
Gravitational-Wave Signatures of Nonstandard Neutrino Properties in Collapsing Stellar Cores
Jakob Ehring (1,2,3)🇹🇼 · Sajad Abbar (2)🇩🇪 · H.-Thomas Janka (3)🇩🇪 · Georg Raffelt (2)🇩🇪 · Ko Nakamura (4)🇯🇵 · Kei Kotake (4,5) ((1) Academia Sinica, Taipei City, Taiwan, (2) MPI Physics, Garching, Germany, (3) MPI Astrophysics, Garching, Germany, (4) Fukuoka University, Japan, (5) University of Wroclaw, Poland)🇯🇵
We present a novel multi-messenger approach for probing nonstandard neutrino properties through the detection of gravitational waves (GWs) from collapsing stellar cores and associated supernova explosions. We show that neutrino flavor conversion inside the proto-neutron star (PNS), motivated by physics Beyond the Standard Model (BSM), can significantly boost PNS convection. This effect leads to large-amplitude GW emission over a wide frequency range during an otherwise relatively quiescent GW phase shortly after core bounce. Such a signal provides a promising new avenue for exploring nonstandard neutrino phenomena and other BSM physics impacting PNS convection.
↳ astro-ph.HEgr-qchep-phPRL(2026)·20 citations
37*
Nucleosynthesis Conditions in Outflows of White Dwarfs Collapsing to Neutron Stars
Eirini Batziou (1,2) · Robert Glas (1)🇩🇪 · H.-Thomas Janka (1)🇩🇪 · Jakob Ehring (3,4,1)🇹🇼 · Ernazar Abdikamalov (5) · Oliver Just (6,7) ((1) MPI Astrophysics, Garching, Germany, (2) TUM School of Natural Sciences, Garching, Germany, (3) Academia Sinica, Taipei City, Taiwan, (4) MPI Physics, Garching, Germany, (5) Nazarbayev University, Astana, Kazakhstan, (6) GSI, Darmstadt, Germany, (7) RIKEN, Saitama, Japan)🇩🇪
Accretion-induced collapse (AIC) or merger-induced collapse (MIC) of white dwarfs (WDs) in binary systems is an interesting path to neutron star (NS) and magnetar formation, alternative to stellar core collapse and NS mergers. Such events could add a population of compact remnants in globular clusters, they are expected to produce yet unidentified electromagnetic transients including gamma-ray and radio bursts, and to act as sources of trans-iron elements, neutrinos, and gravitational waves. Here we present the first long-term (>5s post bounce) hydrodynamical simulations in axi-symmetry (2D), using energy- and velocity-dependent three-flavor neutrino transport based on a two-moment scheme. Our set of six models includes initial WD configurations for different masses, central densities, rotation rates, and angular momentum profiles. Our simulations demonstrate that rotation plays a crucial role for the proto-neutron star (PNS) evolution and ejecta properties. We find early neutron-rich ejecta and an increasingly proton-rich neutrino-driven wind at later times in a non-rotating model, in agreement with electron-capture supernova models. In contrast to that and different from previous results, our rotating models eject proton-rich material initially and increasingly more neutron-rich matter as time advances, because an extended accretion torus forms around the PNS and feeds neutrino-driven bipolar outflows for many seconds. AIC and MIC events are thus potential sites of r-process element production, which may imply constraints on their occurrence rates. Finally, our simulations neglect the effects of triaxial deformation and magnetic fields, yet they provide valuable reference cases for comparison with future long-term magneto-hydrodynamic and three-dimensional AIC studies.
↳ astro-ph.HEhep-phApJ(2025)·15 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.