HEP Phenomenology·hep-ph

Mon·Sep 14, 2026Monday·September 14, 2026

40 papers—29 primary·11 cross-listed

01
Probing anomalous $h Z γ$ couplings in single Higgs production at future muon colliders
Shirin Chenarani · Sara Khatibi
Future multi-TeV muon colliders offer an ideal environment to probe physics beyond the Standard Model (SM) through high-precision measurements. In this work, we investigate the sensitivity to anomalous $h Z γ$ couplings within the dimension-six Standard Model Effective Field Theory (SMEFT) framework at $s = 3 TeV$ and $10 TeV$ muon colliders. Focusing on single Higgs boson production---particularly through vector boson fusion---followed by the rare $h \to Z γ$ decay channel, we perform a comprehensive simulation using \textsc{MadGraph5\_aMC@NLO}, \textsc{Pythia}, and \textsc{Delphes} for fast detector response. To maximize signal sensitivity, we contrast a traditional cut-and-count methodology with a multi-bin Boosted Decision Tree (BDT) shape analysis, evaluated within a multi-bin $χ^{2}$ statistical framework. Our most stringent projections are achieved using the multivariate BDT analysis at $10 TeV$ . Assuming an integrated luminosity of $10 ab^{- 1}$ and a $5%$ systematic uncertainty, we derive expected $95%$ confidence level intervals of $c_{H W} \in [- 0.005, + 0.003]$ and $c_{H B} \in [- 0.003, + 0.005]$ . Notably, the bound on the $c_{γ}$ coefficient is slightly tighter due to its larger cross-section enhancement, reaching $c_{γ} \in [- 0.002, 0.001]$ . These results underscore the unique capability of high-energy muon colliders to constrain anomalous Higgs-gauge couplings.
hep-ph
02
Learning the Geometry of Collider Events with Metric-Aware Deep Sets
Lauren Hay · Rishabh Jain · Matt LeBlanc · Jennifer Roloff
Optimal transport gives structured data a geometry, but exact evaluation is costly in large pairwise analyses that exploit relationships among distances. Learned surrogates are faster, but need not preserve this metric structure. We develop a Deep Sets surrogate for OT between variable-size weighted point clouds that enforces non-negativity, exchange symmetry, and zero self-distance, leaving the triangle inequality unconstrained. Applied to the Energy Mover's Distance between collider events in a particle physics application, the Metric-Aware Particle Flow Network achieves percent-level mean absolute percentage error while significantly improving inference throughput over other exact and approximate methods surveyed. The architectural constraints are found to improve properties that are not explicitly enforced: across $1 0^{6}$ held-out event triplets, triangle-inequality violations fall from 199 for a matched unconstrained network to 2, and the maximum from 149.5 to 5.8 GeV. These results demonstrate that targeted inductive biases can yield fast neural surrogates with substantially improved geometric fidelity.
hep-phcs.LG
03
Nuclear Recoils from Invisible Neutron-Pair Annihilation and the LZ event
Junseok Lee · Fuminobu Takahashi · Yu-Dai Tsai
Two bound neutrons can annihilate into a single invisible scalar carrying baryon number two, producing a monochromatic nuclear recoil. Pair removal connects the $0^{+}$ ground states of even-even nuclei and, for several detector isotopes, leaves a stable daughter where single-neutron removal would leave a radioactive one. Below the first daughter excitation, the leading transition produces neither nuclear de-excitation nor subsequent daughter decay. We identify the corresponding mass windows in argon and xenon, including argon recoils up to $108 keV$ , and obtain an approximate partial-lifetime bound of $8.5 \times 1 0^{26} yr$ from DEAP-3600 data. Recoil lines in different isotopes reconstruct a common invisible-particle mass. The emitted scalar can itself be dark matter, making these searches a probe of ordinary matter converting into a dark sector.
hep-ph
04
Muon decay across scales: from LEFT to SMEFT
Jakob Moritz · Tyler Corbett
We revisit precision muon decay in the framework of the LEFT by considering how the LEFT perturbs the total rate as well as the standard and polarization-dependent Michel parameters. We derive the dependence of these observables on the dimension-five and -six LEFT operators, including lepton number violating operators, allowing for arbitrary neutrino flavor assignments. We consider fits of the LEFT to the muon decay data, in particular an approach to neutrino flavor general fits that does not respect the LEFT power counting and assuming new physics couples to all flavors equally and therefore allows for a consistent fit. We then consider how new physics imprints on the SMEFT and subsequently the LEFT in order to constrain specific scenarios of single-field extensions as well as two motivated two-field extensions. While we infer associated mass scales for these scenarios in the hundreds of GeV to multi-TeV range we also find that for the specific cases of lepton number violation, neutrino mass constraints from operator mixing are more restrictive than muon decay.
hep-ph
05
One-point charge correlator as a probe for the odderon
Haotian Cao · Zhong-Bo Kang · Diego Padilla · Jani Penttala
We propose the one-point charge correlator (OPCC) in transversely polarized deep inelastic scattering as a new probe of the spin-dependent odderon. The OPCC is an infrared and collinear safe observable constructed solely from the charge and angular information of final-state charged particles. Because the charge weight is odd under charge conjugation, the contribution of the C-even pomeron to the OPCC vanishes identically in the small- $x$ eikonal limit, whereas the contribution of the C-odd spin-dependent odderon survives. We define a transverse single-spin asymmetry by normalizing the spin-dependent OPCC to the unpolarized charged-hadron one-point energy correlator. At small $x$ , this asymmetry reduces to a ratio of spin-dependent odderon and pomeron contributions. We provide illustrative estimates of this asymmetry for Electron-Ion Collider kinematics within the small- $x$ dipole framework with Balitsky--Kovchegov evolution to guide experimental studies. Dedicated measurements of the OPCC asymmetry with a transversely polarized proton beam would provide new quantitative constraints on the currently unconstrained spin-dependent odderon.
hep-phnucl-th
06
Driver and damping of the directed-flow response in heavy-ion collisions
Kishora Nayak · Vipul Bairathi
The initial-state geometry plays a crucial role in driving directed flow, while the dissipative response of the medium dampens it. Both of these factors influence how the directed-flow slope varies with system size. We developed a method to differentiate between these driving and damping effects on charged-hadron directed flow in O+O, Cu+Cu, Ru+Ru, Au+Au, and U+U collisions at $s_{NN} = 200$ ~GeV using an improved version of the string-melting AMPT model. We formulated three scaling observables based on the entropy density, the number of participants, and the mass number. A dimensionless ratio was constructed, revealing the threshold mass number $A \approx 35$ in central collisions from the entropy and participant scaling, indicating the onset of collective behavior. We constructed a kinetic-theory Knudsen-number ( $Kn$ ) map to analyze the contributions of the initial-state driver, which grows as $Kn^{κ}$ with $κ \approx 2$ , and a final-state viscous damping of the hydrodynamic response with characteristic scale $Kn_{0} \approx 0.27$ for the directed flow slope. This damping scale is found to be about a factor of 2.5 smaller than the $Kn_{0} \approx 0.7$ extracted from the elliptic flow. Furthermore, we determined the ratio of shear viscosity to entropy density, $η / s$ , to be between 0.10 and 0.20, using an alternative method that does not rely on fitting flow harmonics.
hep-phnucl-th
07
The devil in the transition: NLO nucleation and the particle physics behind the PTA signal
Cristina Puchades-Ibáñez · Pedro Schwaller
We quantify how the treatment of a strongly supercooled phase transition affects the particle-physics interpretation of a nanohertz gravitational-wave signal. For the classically conformal Abelian Higgs model, we calculate the nucleation rate at NLO in the dimensionally reduced theory and test the gradient expansion against explicit fluctuation determinants. A calibrated correction reproduces the determinant exponent with a mean absolute relative difference of $0.8%$ and allows this information to be included throughout the parameter scan. We propagate the corrected rate through percolation, reheating and gravitational-wave production, and confront the resulting spectra with the NANOGrav 15-year and IPTA DR2 data. The corrected NLO calculation shifts the preferred gauge coupling by $9%$ and $13%$ , respectively, and the input scale by $18%$ for NANOGrav. After the determinant calibration, the largest theoretical uncertainties arise from uncertainties in the gravitational-wave spectra and the relation between $R_{⋆}$ and $β / H$ .
hep-phgr-qc
08
Radiative corrections to weak interaction processes
Chien-Yeah Seng
The search for physics beyond the Standard Model in low-energy weak interaction processes requires a precise knowledge of the Standard Model background at tree- and loop-level. In many such cases, radiative corrections represent one of the major sources of theory uncertainty due to the non-perturbative structures of nucleon or nuclei. In this review, I discuss several modern strategies based on dispersion relation, lattice gauge theory and nuclear many-body calculations to pin down the hadronic and nuclear uncertainties in the radiative corrections to low-energy weak interaction processes such as beta decays and parity-violating electron-nucleus scattering.
hep-phhep-exhep-latnucl-ex+1
09
Simple Modular $S_{3}$ Models for Lepton Masses and Mixing
V. V. Vien · Mayengbam Kishan Singh
We perform a systematic study of an economical class of modular $S_{3}$ lepton-flavor models without enlarging the continuous gauge symmetry or introducing right-handed neutrinos or additional flavon fields. We provide a complete classification of all inequivalent realizations allowed by the $S_{3}$ singlet--doublet representation structure and the admissible modular-weight assignments. Their phenomenological viability is investigated for both normal ordering (NO) and inverted ordering (IO) using Bayesian model comparison and parameter-correlation analysis based on current neutrino-oscillation data. We identify 18 viable models for NO and 19 for IO, with 14 satisfying the experimental constraints in both orderings. The viable models successfully accommodate current neutrino-oscillation data while yielding nontrivial predictions for leptonic CP violation, Majorana phases, and observables probing the absolute neutrino-mass scale. Among these predictions, the absolute-mass observables provide the clearest separation between the two orderings. At the best-fit points, the predicted ranges of the effective electron-neutrino mass ( $m_{β}$ ) are completely disjoint between NO and IO, whereas those of the sum of neutrino masses ( $\sum_{i} m_{i}$ ) and the effective Majorana mass ( $m_{β β}$ ) show only partial separation. The IO models generally predict a higher absolute neutrino-mass scale and are consequently more strongly constrained by cosmological observations and more accessible to neutrinoless double-beta-decay searches. Our results show that, despite its economical field content, the modular $S_{3}$ framework accommodates a diverse set of phenomenologically viable lepton-flavor realizations with experimentally testable predictions.
hep-ph
10
Tensor-polarized twist-3 distribution function $f_{L T}$ of spin-1 deuteron
S. Kumano · Kenshi Kuroki
We investigate the twist-2 and twist-3 tensor-polarized partonic structures of the spin-1 deuteron. Using the operator product expansion with local operators, we derive a Wandzura-Wilczek (WW)-like twist-2 relation between the tensor-polarized twist-2 quark distribution $f_{1 LL}$ and the twist-3 distribution $f_{L T}$ , together with a Burkhardt-Cottingham (BC)-like sum rule. The local-operator formalism makes the Lorentz structure and rotational invariance manifest and provides useful constraints on the twist-3 sector. We then use a phenomenological parametrization of the twist-2 distribution $f_{1 LL} (x)$ , constrained by HERMES data on the deuteron structure function $b_{1}$ at $Q^{2} = 2.5 GeV^{2}$ , to quantitatively estimate the twist-3 distribution $f_{L T} (x)$ within the WW approximation. The resulting $f_{L T} (x)$ has a shape and magnitude comparable to those of $f_{1 LL} (x)$ , indicating that subleading-twist effects may be relevant for future experiments at relatively low $Q^{2}$ . In this contribution, we summarize the theoretical derivation of the WW-like relation and BC-like sum rule and present a phenomenological estimate of the tensor-polarized twist-3 quark distribution $f_{L T}$ in the deuteron.
hep-phhep-exhep-latnucl-ex+1
11
Spin-independent scattering of pseudoscalar-mediated dark matter
Nicole F. Bell · Giorgio Busoni · Peter Cox · Laura W. Fang · John Gargalionis · Jayden L. Newstead · Ewan N. V. Wallace · Martin J. White · Anthony G. Williams
Dark matter with pseudoscalar couplings provides a well-motivated scenario in which direct-detection signals are suppressed at tree level, since the scattering off nuclei is both spin-dependent and momentum suppressed. While spin-independent scattering is absent at tree level, it arises at one loop and can provide the leading direct-detection signal. We revisit this scenario in a general sub-electroweak effective field theory with a light pseudoscalar mediator, including interactions through to mass-dimension-six. We compute the matching onto the quark and gluon operators relevant for direct detection to determine whether this scenario could be detectable at future experiments, while also requiring consistency with the observed dark matter relic-abundance and indirect-detection limits. We find that while models with a pseudoscalar mediator can generate spin-independent cross sections above the neutrino floor, this generally requires additional new physics below the TeV scale.
hep-ph
12
DIS Dijet Production: An operator basis bridging eikonal and TMD regimes
Tiyasa Kar · Swagato Mukherjee · Vladimir Skokov · Shaswat Tiwari · Fei Yao
We propose an operator basis for the unpolarized deep-inelastic scattering (DIS) quark-antiquark dijet production process smoothly connecting the all-twist eikonal regime to the back-to-back leading-twist TMD regime at arbitrary Bjorken x. Starting from the background-field quark propagator we construct an operator basis that organizes the eikonal and twist expansions within a unified formulation. Utilizing this operator basis we derive the dijet production amplitudes retaining all contributions required by either the leading-eikonal or the leading-twist description. In the eikonal limit the resulting amplitudes reproduce the all-twist Color Glass Condensate result, while in the back-to-back limit they reduce to the leading-twist gluon TMD-based result at arbitrary x. The operator basis can be systematically extended to include sub-eikonal and higher-twist corrections. Further, by examining the relationship of this operator basis to the improved TMD (iTMD) factorization we recover the iTMD structure in the eikonal limit. However, we find at non-zero x the transverse resummation generates longitudinal phases that prevent factorization in terms of a conventional TMD operator.
hep-ph
13
Leptogenesis Determined By Low Energy Parameters
Xiao-Gang He · Zhong-Lv Huang · Raymond R. Volkas · Yu-Qi Xiao
We study thermal leptogenesis in three predictive type-I seesaw models in which the neutrino Dirac mass matrix is equal to the mass matrix of up-type quarks, or down-type quarks, or charged leptons. In this framework, the seesaw relation permits a full reconstruction of the heavy right-handed neutrino mass matrix from low-energy neutrino parameters, which greatly reduces the parameter freedom. A systematic numerical scan based on density matrix Boltzmann equations is performed to examine whether the observed baryon asymmetry of the Universe can be obtained. Successful leptogenesis occurs for normal ordering of light neutrino masses with nonzero Majorana phases. In this case, viable solutions are found in model B, associated with down-type quarks, and model C, associated with charged leptons. Both point to a close-mass pair of heavy neutrinos satisfying $∣ M_{i} - M_{j} ∣/ M_{i} < 1 0^{- 3}$ , while remaining outside the conventional quasi-degenerate resonant regime. Four representative benchmark points are selected to show the evolution of the asymmetry and the impact of different treatments of spectator effects. Neutrinoless double beta decay is further studied for all parameter points that can generate an acceptable baryon asymmetry $η_{B} = (6.12 \pm 0.20) \times 1 0^{- 10}$ . The predicted effective Majorana mass for certain cases can be probed by next generation experiments with sub-10 meV sensitivity, such as LEGEND-1000, nEXO, JUNO 50 tons, and CUPID-1T. This framework therefore provides clear targets for future searches.
hep-ph
14
Comprehensive study of spectroscopic properties of $D_{(s)}$ mesons
Janki. J. Patel · Dhaval Achary · Dhruvesh Maiya · Keval Gandhi · Nakul R. Soni · Jignesh N. Pandya
We decode the excited open charm mesons $D$ ( $c q ˉ$ , $q = u, d$ ) and charm strange $D_{s}$ ( $c s ˉ$ ) families within a nonrelativistic quark-antiquark potential model based on the Cornell (Coulomb plus linear) potential supplemented by a Gaussian smeared spin-spin interaction. With only seven parameters determined by fitting the ground state masses, the numerically solved Schrödinger equation reproduces the masses of essentially every confirmed $D$ and $D_{s}$ state to better than $1%$ . The same wave functions are then employed to get a complete decay analysis including pseudoscalar and vector decay constants ( $f_{D} = 231.8$ ~MeV, $f_{D_{s}} = 252.2$ ~MeV, the latter within $0.4%$ of the world average), leptonic branching fractions reproducing the measured $μν$ and $τ ν$ modes, electromagnetic $E 1$ / $M 1$ widths, and all kinematically open strong channels in heavy quark effective theory (HQET). Going beyond width ratios, we extract the full set of HQET couplings $g_{H}$ , $g_{S}$ , $g_{T}$ , $g_{X}$ , $g_{Y}$ , $g_{Z}$ , and $g_{R}$ directly from the measured total widths and convert our predictions into absolute widths. The $D$ and $D_{s}$ sector extractions of each coupling agree ( $g_{T} = 0.42$ vs. $0.39$ , $g_{X} = 0.22$ vs. $0.21$ , $g_{Y} = 0.39$ vs. $0.40$ ), a nontrivial test of heavy quark flavor symmetry, while the pure $c s ˉ$ picture demands a $1^{3} P_{0}$ width nearly two orders of magnitude above the observed $D_{s 0}^{*} (2317)$ bound demanding it to be of exotic nature. Linear and parallel Regge trajectories in the $(J, M^{2})$ and $(n_{r}, M^{2})$ planes, with slopes $α ≃ 0.55 - 0.65$ ~GeV $^{- 2}$ and $β ≃ 0.36 - 0.39$ ~GeV $^{- 2}$ , identify the assignments of $D_{J} (3000)^{0}$ , $D_{J}^{*} (3000)^{0}$ , and $D_{2}^{*} (3000)^{0}$ as the $3^{1} S_{0}$ , $3^{3} S_{1}$ , and $3^{3} P_{2}$ states. Our predictions provide concrete, testable targets for LHCb, BESIII, and Belle~II.
hep-ph
15
Minimal Flavoured DFSZ Axion Models: Predictive Yukawa Textures and Flavour Constraints
Peter Cox · Maaz Hayat · Raymond R. Volkas
We study a predictive class of flavoured DFSZ axion models in which the Peccei--Quinn symmetry is fully horizontal and the domain wall number is unity. These Minimal F-DFSZ models simultaneously resolve the strong CP problem and avoid the post-inflationary domain wall problem, while enforcing a predictive set of texture-zero quark mass matrices. Remarkably, the entire quark Yukawa sector can be reconstructed in terms of the measured quark masses and Cabibbo--Kobayashi--Maskawa parameters. We derive analytic expressions for the resulting flavour-violating Higgs and axion couplings, thereby making explicit how the new-physics effects are determined by Standard Model observables. We then analyse the full flavour phenomenology of the framework and obtain bounds on the scale of new physics from precision flavour observables.
hep-ph
16
Observables in exclusive heavy quarkonium electroproduction at NLO and prospects for the EIC
Chris A. Flett
We perform various phenomenological studies of exclusive heavy-quarkonium electroproduction in $e p$ collisions that are relevant for both the existing measurements from HERA and the forthcoming Electron-Ion Collider (EIC). We provide quantitative predictions at next-to-leading order (NLO) in perturbative QCD (pQCD) for various observables accessible at HERA for $J / ψ$ electroproduction that serve as valuable benchmarks across a broad range of photon virtualities $Q^{2}$ and $γ^{*} p$ centre-of-mass energies. We then discuss how the forthcoming EIC will complement existing measurements and end by advocating the need for a dedicated and systematic resummation framework for $J / ψ$ electroproduction at large $Q^{2}$ .
hep-phhep-ex
17
Phase Structure and Gravitational-Wave Phenomenology of a Thermal First-Order Phase Transition
Gayatri Ghosh
We investigate the phase structure and gravitational-wave (GW) phenomenology of a cosmological first-order phase transition described by the finite-temperature effective potential $V (ϕ, T) = D (T^{2} - T_{0}^{2}) ϕ^{2} - E T ϕ^{3} + λ ϕ^{4} /4$ . We derive the critical temperature and the broken-phase order parameter and identify the dimensionless combination $E^{2} / (D λ)$ that controls the critical-temperature shift. We then construct a dense numerical atlas containing $30000$ parameter points and map the resulting transition parameters onto the characteristic GW frequency and peak amplitude. The scan resolves the multidimensional correlations among $T_{*}$ , $α$ , $β / H_{*}$ , $v_{w}$ , $f_{peak}$ and $Ω_{GW}^{peak} h^{2}$ . The present analysis is phenomenological: $T_{*}$ is defined by the prescription $T_{*} = 0.95 T_{c}$ , while $β / H_{*}$ and $v_{w}$ are treated as scan inputs. Consequently, the resulting GW signals are not interpreted as first-principles predictions. We identify the additional ingredients required for a predictive calculation, including the thermal bounce action, nucleation and percolation temperatures, the transition duration and a microscopic treatment of bubble-wall friction. The resulting framework provides a systematic numerical characterization of the connection between the phase structure of the finite-temperature potential and the corresponding phenomenological GW parameter space.
hep-ph
18
Comparision of modeling of prompt photon production in proton-proton collisions at energies NICA $s$ =10 GeV in PYTHIA and calculations using FeynCalc
Mohsun R.Alizada · Azar I.Akhmedov · Sarhaddin K.Abdullayev · Mejid Sh.Gojayev · Mammed R.Rajabov
The process of prompt photon production in proton-proton collisions at energies of $s$ =10 GeV at the NICA accelerator complex, modulated using PYTHIA 8.316 and calculated in FeynCalc. The main focus is on three main subprocesses: Compton scattering of a quark-gluon $q g \to q γ$ , annihilation of a quark-antiquark pair $q q ˉ \to g γ$ and bremsstrahlung of quarks $q q \to q q γ$ . Main statistical parameters: number of produced prompt photon on photon energy, rapidity and invariant mass photon pairs are determined. The distribution of the number of produced photons by energy $E_{γ}$ and rapidity photons can be mathematically described by the logarithmic-normal and normal law, correspondingly. The analysis shows that Compton scattering of a quark-gluon $q g \to q γ$ makes a dominant contribution to the total cross section of the process, accounting for 51.27\%, while the contributions of annihilation of quark-antiquark pair $q q ˉ \to g γ$ and bremsstrahlung of quarks $q q \to q q γ$ , correspondingly are is 47.22\% and 0.003\%. The difference between the results obtained from the PYTHIA modeling and those calculated by FeynCalc is explained. The use of modern modeling tools such as PYTHIA not only improves the accuracy of experimental predictions, but also plays a key role in the development of new technologies for particle detection and data analysis.
hep-ph
19
Associated $W$ + charm production: indications for PDF analysis
Ville Alanko · Ilkka Helenius · Hannu Paukkunen
The strange quark and antiquark contents of the proton remain weakly constrained compared to the other light quarks, particularly the asymmetry between the two. Production of a $W^{\mp}$ boson in association with a charmed meson $D^{(*) \pm}$ could provide additional constraints in future fits of parton distribution functions. We calculate this process in general-mass variable-flavor-number scheme at next-to-leading order in perturbative Quantum Chromodynamics. We investigate the production ratio between events with oppositely charged $W$ bosons, in which various theoretical uncertainties largely cancel while sensitivity to PDFs remains. We compare our predictions for this quantity with the recent ATLAS data at $s = 13$ TeV and find that CT18ANLO, which sets the strangeness asymmetry to zero, yields good agreement with the data while MSHT20NLO and NNPDF4.0NLO, which have positive strangeness asymmetry in the relevant range of momentum fraction $x$ , show more tension with the data. An approximate PDF-level analysis of the production ratio indicates that this tension could be attributed to a too large strangeness asymmetry.
hep-ph
20
Reconstructing the Dark Matter Equation of State with Compact Object Inspirals
Boris Betancourt Kamenetskaia · Qianhang Ding · Hui-Yu Zhu
We investigate the gravitational wave (GW) signatures of compact binaries embedded in extended dark matter (DM) configurations in hydrostatic equilibrium. If a neutron star is surrounded by a sufficiently massive and extended envelope, an inspiraling companion experiences dynamical friction (DF) in addition to the standard GW energy loss. We show that this environmental effect can be isolated through a GW observable, the $D$ -function, which directly characterizes the additional dissipative power induced by the surrounding medium. Since the density of the envelope is directly determined by the DM equation of state together with the stellar boundary conditions, the frequency dependence of the $D$ -function provides direct information about the macroscopic properties of the dark sector. We develop a regression-based framework to reconstruct both the density profile and the DM equation of state over the density range probed by observations of the GW inspiral. Using representative DM models as benchmarks, we demonstrate that the method accurately recovers the input equation of state while remaining largely independent of the microscopic realization of DM. Our results show that future GW observations of compact binaries can provide a probe of the equation of state of DM.
hep-phastro-ph.HEgr-qc
21
Supernova cooling from neutrinophilic dark matter
Yugen Lin
Core-collapse supernova serve as a powerful laboratory for testing physics beyond the Standard Model (BSM), particularly regarding new, light states interacting feebly with SM particles. In this work, we investigate for the first time the production of dark matter (DM) via the neutrino-neutrino scattering processes inside a core-collapse supernova, which contributes to the excessive cooling. By incorporating state-of-the-art supernova simulation data , we derive stringent and robust limits on sub-GeV dark matter with effective couplings to neutrinos. We find that the existing and projected constraints from indirect detection are quite weak. Our supernova cooling bounds on DM-neutrino reference cross section can improve indirect detection limits more than ten orders of magnitude for DM masses below $O (100)$ MeV, and it can also provide strong complementarity with other cosmological constraints. Our results highlight the exceptional sensitivity of core-collapse supernova to feebly interacting particles and motivate future supernova neutrino observations as a powerful probe of light dark sectors.
hep-ph
22
Gauge-invariant Higgs mechanism via gradient-flow regularization
Gunnar S. Bali
We provide a manifestly gauge-invariant description of the Higgs mechanism in the Standard Model, casting it not as the breaking of a local symmetry, but as a smooth, analytic crossover from a high-temperature symmetric phase to a low-temperature Higgs phase. Taking the vacuum expectation value of a gauge-invariant local scalar operator and constructing composite quasi-particle states from the original fields of the Lagrangian usually introduces contact-term divergences. Previous attempts to circumvent this issue via bilocal operators remain unsatisfactory. Here we demonstrate that the gradient flow at a flow time $t$ provides a clean, structurally sound, and Lorentz-covariant regularization that permits a consistent, renormalon-free matching onto the standard $MS$ scheme at a scale $μ \sim 1/ 2 t ≫ m_{t}$ . Beyond its theoretical appeal, this construction clarifies a number of conceptional and practical questions. We demonstrate the utility of this framework at the one-loop level, thereby establishing the foundation for future electroweak precision physics in this approach.
hep-phhep-lathep-th
23
What has the LHC told us about the electroweakino sector of the Minimal Supersymmetric Standard Model?
Peter Athron · Csaba Balázs · Andy Buckley · Jon Butterworth · Christopher Chang · Andrew Fowlie · Tomás E. Gonzalo · Vinay Hegde · Ida-Marie Fauske Johansson · Adil Jueid · Tore Klungland · Anders Kvellestad and 10 other authors
We perform global fits of the electroweak sector of the Minimal Supersymmetric Standard Model (MSSM) using a comprehensive set of LEP searches, 34 Run 2 LHC searches, and 63 Run 2 LHC measurements. Scanning the bino, wino and Higgsino mass parameters, and the ratio of the Higgs vacuum expectation values, we find that for a light, bino $χ ~_{1}^{0}$ , the mass of the next-to-lightest neutralino must be $m_{χ ~_{2}^{0}} ≳ 760$ GeV. While MSSM electroweakinos can explain individual excesses observed by ATLAS and CMS in searches targeting compressed spectra, we find no scenarios that fit these excesses simultaneously. When we add a light gravitino, neutralinos are further excluded up to about 1 TeV, though this depends on their composition; Higgsino-dominated $χ ~_{1}^{0}$ requires only $m_{χ ~_{1}^{0}} \approx m_{χ ~_{2}^{0}} ≳ 650$ GeV. Lastly, the newer LHC searches and measurements exclude a low-mass region that was preferred in a previous study. This is the most complete summary of collider constraints on the electroweakino sector of the MSSM performed to date.
hep-ph
24
NNLL resummation for the production of four top quarks
Melissa van Beekveld · Anna Kulesza · Michele Lupattelli · Tommaso Saracco
Four-top production is one of the rarest processes of the Standard Model observable at the Large Hadron Collider, offering sensitivity to the top Yukawa coupling, Higgs width, and beyond-Standard-Model physics. We present precise predictions for the invariant-mass distribution and total cross section using threshold resummation at next-to-next-to-leading logarithmic (NNLL) accuracy, matched to next-to-leading order (NLO) calculations.
hep-ph
25
Probing Neutrinophilic Axion-Like Particles in Tritium Beta Decay
Yi Chung · Florian Goertz · Maya Hager · Joscha Lauer
We investigate the prospects for constraining neutrinophilic axion-like particles via measurements of the tritium beta decay spectrum, as performed by the KATRIN experiment and its planned TRISTAN detector upgrade. We study in detail the resulting spectral modifications and the corresponding experimental sensitivity. The relevant complementary searches are also discussed for comparison and we derive the most up-to-date and robust constraints on keV-scale neutrinophilic axion-like particles, covering both lepton-number-conserving and lepton-number-violating interactions. Cosmological constraints are generally more stringent; however, this conclusion relies on the assumption that the particles remain unchanged from the early universe to the present day. We therefore construct a model in which the neutrinophilic axion-like particle, being a pseudo-Nambu-Goldstone boson of an extended scalar sector, emerges from a spontaneous symmetry breaking featuring a non-trivial thermal history. We show that the model naturally evades the conventional cosmological bounds, allowing tritium beta decay measurements to provide the leading constraints.
hep-phhep-ex
26
Can a minimal radiative seesaw explain the LZ 248 keV event?
Hiroshi Okada · Yoshihiro Shigekami · Jia-Jun Wu
We interpret the recently reported 248~keV nuclear recoil event in the LUX-ZEPLIN (LZ) experiment via inelastic dark matter scattering within the minimal Scotogenic model. A sub-MeV mass splitting between neutral inert scalars suppresses low-energy scattering while permitting signals from the high-velocity halo tail. Crucially, co-annihilation with nearly degenerate right-handed fermions accommodates the thermal relic density for dark matter masses up to $\sim O (1)$ ~TeV, extending the viable range significantly beyond the pure inert doublet model limit while evading direct detection bounds. However, to resolve the severe tension with IceCube neutrino limits on solar capture, we extend this minimal framework by introducing a hidden $U (1)_{X}$ gauge symmetry that naturally leads us to tiny $λ_{5}$ coupling at the one-loop level. This realizes an isospin-violating scenario that suppresses dark matter capture in the Sun while preserving the coherent scattering signal in the Xenon-based LZ detector. We numerically verify that this extended framework naturally generates neutrino masses and satisfies constraints from Big Bang Nucleosynthesis and indirect detection, providing a robust and testable solution to the LZ anomaly.
hep-ph
27
$B_{(s)} \to V M_{X}$ decays as probes of dark-matter scenarios of Belle II enhancement in $B \to K M_{X}$ decays
Alexander Berezhnoy · Wolfgang Lucha · Dmitri Melikhov
Recently, we have shown that the hypothesis of the dark-matter (DM) origin of the Belle II excess events in $B \to K M_{X}$ decays allows for a successful description of the data. The DM parameters (masses and couplings) in two DM scenarios with either scalar (S-scenario) or vector (V-scenario) mediator have been extracted with rather small uncertainty from fits to the $B \to K M_{X}$ data. The same mechanism leads to a similar enhancement of the $B_{s} \to (η, η^{'}, ϕ) M_{X}$ decay rates. We present a detailed analysis of $B \to K^{*} M_{X}$ and $B_{s} \to ϕ M_{X}$ decays and show that these decays provide a clear probe of the S- and V-scenarios: Compared to the Standard Model, in the S-scenario an enhancement by a factor $\sim 1.6$ is expected, whereas the V-scenario leads to a much larger enhancement by a factor $\sim 3.5$ . For the $B \to K^{*} M_{X}$ decays, we provide the expected number of events at Belle II for the sample for which a rather large enhancement of $B \to K M_{X}$ decays compared to the Standard Model expectations has been reported.
hep-ph
28
Radion--QCD Interference in $t t ˉ$ Production at the HL-LHC: Finite-Top-Mass Effects and Projected Sensitivity
Ahmed Bellagroudi · Farida Fassi
We investigate the interference of a heavy radion with the QCD continuum in top-quark-pair production at the High-Luminosity Large Hadron Collider, restricting the numerical study to the pure-radion limit $ξ = 0$ . The gluon-fusion amplitude combines the QCD trace anomaly with the exact finite-top-mass loop form factor, whose coherent sum fixes both the magnitude and the phase of the production coefficient. Above the top threshold the loop develops an absorptive part, rendering the production coefficient complex and allowing the interference to remain non-zero on the resonance pole, where a purely real point-like coefficient would give none. The complex coefficient is validated independently using a native loop-induced implementation and a common-event phase-basis construction. The resulting signature is a peak--dip deformation rather than a positive bump, while detector smearing turns the narrow truth-level structure into a broad sub-percent distortion. For $3 ab^{- 1}$ at $s = 14$ TeV, we construct an ATLAS-anchored phenomenological response and perform an exact binned Poisson Asimov analysis with a free background normalization and a correlated shape nuisance. For a $0.1%$ shape benchmark with a $50$ GeV correlation length, the profiled median $95%$ $C L_{s}$ reach in $Λ_{r}$ is $2.49$ , $2.82$ , $3.00$ , $2.56$ , and $2.19$ TeV for radion masses of $600$ , $800$ , $1000$ , $1200$ , and $1500$ GeV, respectively. A diagnostic decomposition at $800$ GeV gives $2.18$ TeV for the resonance-squared term alone and $2.83$ TeV for the interference term alone. A selected-background deformation stress test largely removes the apparent maximum near $1$ TeV, showing that its location and prominence are normalization-prescription dependent, while leaving the central conclusion unchanged: the projected sensitivity is predominantly interference driven.
hep-ph
29
A Freeze-In Interpretation of the LZ High-Energy Nuclear Recoil Event
D. Cabo-Almeida · F. Costa · D. Feiteira · V. Oliveira
The recent LUX-ZEPLIN (LZ) experiment analysis reported a high energy nuclear recoil candidate at $E_{R} ≃ 248 keV$ , motivating interpretations in terms of inelastic dark matter. We study this event in a pseudo-Dirac fermion model with a vector boson mediator $Z^{'}$ , assuming a low reheating temperature and dark matter production through freeze-in at stronger coupling. In contrast to the thermal freeze-out case, the reheating temperature provides an additional parameter controlling the relic abundance and breaks the one-to-one relation between the dark matter mass and direct-detection cross section. As a result, the LZ candidate can be reproduced over a continuous region of parameter space, including mass splitting below the thermal benchmark.
hep-ph
30
Constraining dark matter using 20-year INTEGRAL/IBIS observations I: Primordial black holes
Jordan Koechler · Pedro De la Torre Luque
Primordial black holes (PBHs) in the asteroid-mass window remain a viable dark matter candidate. In the lower part of this mass range, Hawking evaporation produces electrons and positrons that generate diffuse hard X-ray emission through inverse Compton (IC) scattering on Galactic radiation fields. We present the first search for this signal using a combined spectral and morphological analysis of the 20-year INTEGRAL/IBIS observations. We construct a physically motivated model of the Galactic hard X-ray background, including IC emission from cosmic-ray electrons and unresolved accreting white dwarfs, and consistently incorporate the IC contribution from PBH evaporation. By exploiting both spatial and spectral information, we improve the separation between a possible PBH signal and astrophysical backgrounds compared to analyses based only on spectral data. We derive constraints on the PBH dark matter fraction over a broad mass range, including extended PBH mass functions and rotating PBHs. We assess the impact of uncertainties in cosmic-ray propagation and the Galactic dark matter density profile, finding that the propagation of low-energy electrons and positrons represents the main source of uncertainty in the predicted signal. Despite these limitations, our results provide competitive constraints over a wide range of PBH masses, highlighting the potential of hard X-ray observations as a complementary probe of evaporating PBHs.
↳ astro-ph.HEastro-ph.COhep-ph
31
Constraining Ultralight Scalars with Black Hole Binary Mergers in Galactic Nuclei
Majed Khalaf · Eric Kuflik · Alessandro Lenoci · Nicholas Chamberlain Stone · Ofri Telem
Ultralight scalars can form long-lived, macroscopic bound states around spinning black holes, known as superradiance clouds. These clouds provide an additional channel for energy dissipation during close encounters, enhancing the black hole binary formation and merger rates in dense environments such as galactic nuclei. We show that the rate of mergers with mass ratio below $3/10$ in the LIGO-Virgo-KAGRA GWTC-5 catalog can probe ultralight scalars in the mass range $[4 \times 1 0^{- 14}, 1 0^{- 13}]$ eV, complementing existing strategies based on black hole spin measurements.
↳ gr-qcastro-ph.HEhep-ph
32
The Role of Big Bang Nucleosynthesis in Joint Cosmological Analyses
Mehmet Akharman · Nicholas DePorzio · Cara Giovanetti · Hongwan Liu
We perform joint Baryon Acoustic Oscillation (BAO) + Big Bang Nucleosynthesis (BBN) and BAO+BBN+Cosmic Microwave Background (CMB) analyses with Planck CMB and DESI DR2 BAO data, explicitly marginalizing over BBN nuisance parameters for the first time with these data combinations and paying particular attention to the impact of BBN on these results. We find in our fiducial analyses $h = 0.683 3_{- 0.0053}^{+ 0.0048}$ ( $Λ$ CDM, BAO+BBN), $h = 0.682 3_{- 0.0026}^{+ 0.0027}$ ( $Λ$ CDM, BAO+BBN+CMB), as well as $h = 0.679 1_{- 0.0075}^{+ 0.0069}, N_{eff} = 2.97 4_{- 0.099}^{+ 0.098}$ ( $Λ$ CDM+ $N_{eff}$ , BAO+BBN), and $h = 0.683 8_{- 0.0054}^{+ 0.0052}, N_{eff} = 3.06 5_{- 0.076}^{+ 0.078}$ ( $Λ$ CDM+ $N_{eff}$ , BAO+BBN+CMB). We demonstrate how investigator choices can impact results of joint analyses involving BBN. We provide recommendations for the treatment of BBN in light of recent work, and demonstrate a pipeline that accurately accounts for prediction uncertainties in BBN.
↳ astro-ph.COhep-ph
33
Emergent Conformal Symmetry on Superfluid Vortices in Two-Color QCD and Pseudoreal Gauge Theories
Muneto Nitta
Two-color QCD provides a unique first-principles laboratory for strongly interacting matter at finite baryon density, where a diquark condensate realizes a baryonic superfluid. We investigate the internal physics of its quantized superfluid vortices in the chiral limit. We find that a vortex localizes an exact and normalizable $S^{3} ≃ S U (2)$ family of pion modes. Remarkably, the bulk Wess--Zumino--Witten (WZW) term induces a quantized WZW term for these modes, driving the vortex theory in the infrared to the $S U (2)_{1}$ WZW conformal field theory with central charge $c = 1$ . Thus a strongly coupled conformal theory emerges on a vortex in a nonconformal bulk theory. The mechanism extends to pseudoreal $S p (2 N)$ gauge theories, where the corresponding minimal vortex theory flows to $S U (2)_{N}$ , with the level directly encoding the microscopic anomaly coefficient.
↳ hep-thhep-lathep-ph
34
Probing Lorentz Invariance Violation in Cosmogenic Neutrino Propagation with KM3-230213A
Rodrigo Sasse · Rodrigo Guedes Lang · Rita de Cássia dos Anjos
We investigate superluminal Lorentz invariance violation (LIV) in the neutrino sector using cosmogenic neutrino fluxes generated with ultrahigh-energy cosmic-ray propagation models. Standard fluxes are calculated with \texttt{CRPropa 3.2} and subsequently modified using a prescription based on LIV-induced neutrino splitting. Superluminal LIV suppresses the flux at the highest energies while producing an enhancement at PeV - EeV energies. We use the KM3-230213A event as a benchmark to evaluate the sensitivity of current observations to these spectral modifications. Although the available statistics do not allow a formal constraint, the predicted fluxes are particularly sensitive to coefficients in the range $1 0^{- 24} eV^{- 1} ≲ δ_{ν, 1} ≲ 1 0^{- 22} eV^{- 1}$ , with the results strongly depending on the assumed cosmic-ray source properties. Intermediate coefficients can enhance the expected event rate within the reconstructed energy range of KM3-230213A, whereas larger coefficients may overproduce neutrinos in energy intervals constrained by IceCube and the Pierre Auger Observatory. These results identify a region of observational sensitivity to LIV and provide testable predictions for future neutrino telescopes.
↳ astro-ph.HEhep-ph
35
Intrinsic pressure anisotropy in spherical Proca stars
Ilídio Lopes
Pressure anisotropy in relativistic stars is commonly prescribed through a phenomenological closure, obscuring its microscopic origin and relation to stress-energy conservation. Here it is derived directly from the minimally coupled Einstein-complex-Proca theory. For spherical Proca stars, the principal-pressure difference admits an exact on-shell form whose sign is controlled solely by the local mass-shell threshold. The stress is radially dominated in the core, reverses on a surface of fixed gravitational redshift, and becomes tangentially dominated in the envelope. At the first mass maximum, the fractional anisotropy reaches about 21% near the density maximum, whilst the region beyond the reversal contains about 9% of the mass. Its exact atmospheric limit is approximately 24%, equal in magnitude and opposite in sign to the scalar-boson-star limit. Because the usual local fluid variables remain non-zero at the crossing, no sign-definite closure constructed from them can reproduce the profile. These results identify an intrinsically vectorial stress reversal, generated without additional interactions, and provide a first-principles benchmark for anisotropic bosonic compact objects.
↳ gr-qcastro-ph.HEhep-phhep-th
36
Constraints on Galactic Dark Photons from a DALI Prototype
Javier De Miguel · Antonios Gardikiotis · Elvio Hernández-Suárez · Roger J. Hoyland · Enrique Joven · Abaz Kryemadhi · Haroldo Lorenzo-Hernández · Marios Maroudas · Chiko Otani · J. Alberto Rubiño-Martín · Yannis K. Semertzidis · Michael E. Tobar · Konstantin Zioutas
An analysis of 36 hours of data from a DALI haloscope reveals no statistically significant excess attributable to dark-photon dark matter. We therefore set new constraints in the 6.88691--6.91792 GHz band, reaching a dark-photon-to-photon kinetic mixing strength of $χ ≲ 6.8 \times 1 0^{- 14}$ at $28.54 μ eV$ . To our knowledge, this result established the strongest laboratory-based exclusion limit in this frequency range.
↳ hep-exastro-ph.COhep-ph
37
The DALI Haloscope: A Magnetized Phased Array Coupled to a Semi-Open Fabry--Pérot Resonator
Javier De Miguel · Antonios Gardikiotis · Eduardo David González-Carretero · Elvio Hernández-Suárez · Roger J. Hoyland · Enrique Joven · Abaz Kryemadhi · Marios Maroudas · Chiko Otani · J. Alberto Rubiño-Martín · Yannis K. Semertzidis · Michael E. Tobar · Konstantin Zioutas
DALI is an axion haloscope consisting of a magnetized phased array backed by a conducting mirror and coupled in the near field to a semi-open Fabry--Pérot resonator. The applied static magnetic field makes both the dielectric interfaces and the conducting mirror sensitive to axion-induced electromagnetic conversion. Each interface acts as a radiating surface, and the resulting fields are projected onto the mode collected by the resonator and delivered to the receiver. We derive the detected power in terms of the power available from the magnetized mirror, the coherent contribution of the dielectric interfaces, the transverse mode overlap, the loaded quality factor, and the receiver-coupling coefficient. This formulation separates two distinct enhancement mechanisms. The dielectric-interface emissions may add coherently, producing a dielectric boost, while the semi-open Fabry--Pérot resonator provides enhancement through resonant storage of the coupled electromagnetic field. These contributions depend differently on the dielectric thicknesses, spacings, and resonant mode, and should therefore be evaluated independently. The same assembly can operate between the limits of a coherently boosted dielectric haloscope and a mirror-sourced, resonantly enhanced Fabry--Pérot haloscope. This combined architecture offers a flexible approach to resonant axion searches at frequencies for which conventional closed microwave cavities become increasingly limited in conversion volume.
↳ hep-exastro-ph.COhep-ph
38
Probing Inflationary Origins of Primordial Black Holes with LIGO--Virgo--KAGRA O1--O4a data
Haipeng An · Huai-Ke Guo · Mai Qiao · Lian-Tao Wang · Chen Yang · Yue Zhao
Large primordial curvature perturbations not only produce primordial black holes (PBHs) but also inevitably source a scalar-induced stochastic gravitational-wave background upon horizon reentry. We analyze the combined LIGO--Virgo--KAGRA O1--O4a data to constrain two representative inflationary mechanisms for generating such perturbations: ultra-slow-roll inflation and an inflationary phase transition. Detecting no evidence for either scenario, we place 95% credible upper limits on the curvature-spectrum amplitude across the frequency range accessible to ground-based interferometers. Translated into the PBH context, these limits already exceed conventional constraints, probing abundance fractions far below unity. Our results remain robust even when the PBHs themselves are too rare to be directly detected or have evaporated. This work demonstrates that stochastic gravitational-wave observations offer a powerful and complementary probe of small-scale inflationary physics and PBH formation, with upcoming interferometers promising to extend sensitivity to a wider range of inflationary epochs and PBH masses.
↳ astro-ph.COgr-qchep-ph
39
High-redshift supermassive black hole population from core-collapse in self-interacting dark matter halos
Sambo Sarkar · Ujjal Kumar Dey
Self-interactions between dark matter (DM) particles facilitate the inter-particle redistribution of energy within the central region of DM halos. Recent studies of dark matter spikes around massive black holes, and the diversity in rotation curves of dark matter rich low-mass galaxies motivate the exploration of self-interaction cross-section $O (10) c m^{2} /gm$ . At such high scattering rates, DM can lead to the formation of supermassive black hole seeds, through the gravothermal collapse of halo cores, under certain cosmological conditions. Quasars near cosmic dawn are powerful probes for examining the formation scenario of high redshift supermassive black holes, and their connection to structure formation. In this work we point out the favorable initial cosmological conditions that are likely to provide the black hole seeds resulting in supermassive black holes, mediated by core-collapse in self-interacting dark matter halos. Employing a semi-analytic prescription of core formation, and realistic mass accretion and halo merger histories, we compare the existing observations of high-redshift supermassive black holes with those predicted for our core-collapse framework. We find the median values of velocity-dependent self-interacting dark matter parameter space $σ / m_{χ} \sim 56 c m^{2} /gm$ , and $ω = 101 km/s$ , assuming an Eddington accretion rate of unity. Sub-leading values are also presented for sub and super-Eddington accretion rates. We also report the derived self-interacting dark matter model parameters to account for the observed binned supermassive black hole mass functions at high-redshifts.
↳ astro-ph.GAastro-ph.COhep-ph
40
Particlelike solutions of the Einstein-Dirac-Higgs equations: ground, excited, and many-fermion states
Reinosuke Kusano · Keith Horne · Peter E. D. Leith · Miguel Yulo Asuncion · Chris A. Hooley
We present an extended study of the gravitationally localized soliton-like solutions to the minimally-coupled Einstein-Dirac-Higgs equations, embedded in asymptotically Minkowski spacetimes. The equations of motion describing these Yukawa-coupled Dirac stars are generalized to any even number of constituent fermions. We first expand the discussion of two-fermion ground-state solutions initially analyzed in Leith et al. [Phys. Rev. D. 107, 106020 (2023)]. Upon extending our analysis to excited states and many-fermion states, we find that both exhibit different behaviors to their two-fermion ground-state counterparts. In these excited states and many-fermion states, the Higgs field may exhibit stepwise increases and at times decrease within the soliton, which has not been seen for the two-fermion ground states. We also propose the potential cause of a significant degree of ADM-to-fermion mass disparity, which is present in states with strong Yukawa-coupling.
↳ gr-qchep-phhep-thmath-ph+2