HEP Phenomenology·hep-ph

Wed·Jun 17, 2026Wednesday·June 17, 2026

30 papers—14 primary·16 cross-listed

01
Are neutrinos Majorana? Fixed-target and high-energy astrophysical searches decide
Gabriela Barenboim🇪🇸 · Mauricio Bustamante🇩🇰 · Qinrui Liu🇨🇦
Determining whether the neutrino is a Dirac or Majorana fermion remains a fundamental open question. Conventional searches rely on neutrinoless double beta decay, but this electron-only channel suffers from blind spots. We propose a new, complementary probe to overcome this limitation. A heavy neutral lepton (HNL) triggers a high-energy shift in how the active neutrino flavors ( $ν_{e}$ , $ν_{μ}$ , $ν_{τ}$ ) mix -- but only if the neutrinos are Majorana. For GeV-scale HNLs, the upcoming beam-dump experiment SHiP can discover the HNL and measure how it mixes with the active flavors. Separately, the scattering of TeV--PeV astrophysical neutrinos can resolve the HNL, revealing a shift in the proportions of each flavor arriving at Earth that could be detected by neutrino telescopes, regardless of the unknown flavor composition at the astrophysical neutrino sources. Because this flavor shift is most sensitive to the muon and tau sectors, it bypasses the blind spots of neutrinoless double beta decay. A correlated signal at SHiP and next-generation neutrino telescopes would prove that neutrinos are Majorana; its absence would point to them being Dirac.
hep-phastro-ph.HEhep-exhep-th+10 citations
02
Short-Range Correlations Between Partons in a Proton
Jen-Chieh Peng🇺🇸 · Krishna Rajagopal🇺🇸 · John Terry🇺🇸
A principal lesson from recreating droplets of quark-gluon plasma (QGP) in heavy ion collisions is that it is a strongly coupled liquid, not a plasma of partons. The energy density and pressure of quarks and gluons confined within a proton are comparable to those of QGP at or just above the QCD transition temperature. Given this similarity between protons and QGP, we propose that the investigation of correlations between nearby partons within a proton must be a central goal for the future Electron-Ion Collider (EIC). Here, we ask how EIC measurements can discern such short-range correlations (SRCs) of quark pairs. Doing so would characterize the strongly coupled interior of a proton, augmenting the one-parton-at-a-time understanding of protons via (generalized) parton distribution functions, and could at the same time yield a key ingredient for the microscopic understanding of the liquid nature of QGP. Motivated by the experiments that have been used to demonstrate the existence of SRCs between nucleon pairs within a nucleus, we propose using EIC observables involving measurements of a jet and a pion, together with the scattered electron, to seek and quantify the possible existence of SRCs between quark pairs within a nucleon. The pronounced isospin dependence observed in the dominance of $n p$ SRCs over $pp$ or $nn$ SRCs has played a central role in establishing the importance of SRCs among nucleons in nuclei. Analogously, the QCD attraction in the $u d$ diquark channel can make the $u d$ SRC stronger than the $uu$ and $dd$ SRCs, allowing a first observation of partonic SRCs.
hep-phnucl-exnucl-th0 citations
03
PineAPPLv1: fast and flexible theory predictions for present and future colliders
Tomáš Ježo🇩🇪 · Emanuele R. Nocera🇮🇹 · Tanjona R. Rabemananjara🇫🇷 · Christopher Schwan🇩🇪 · Tanishq Sharma🇮🇹 · Jan Wissmann🇩🇪
We present PineAPPLv1, a library designed to provide accurate and flexible interpolation tables of partonic cross sections that can be convolved with parton distribution functions (PDFs) and fragmentation functions (FFs) for the fast evaluation of high-energy physical observables. The core feature of the new release is the support of multiple convolutions involving initial- and final-state hadronic particles, with any polarisation, that are associated with PDFs and FFs. The library simultaneously supports polarised and unpolarised distributions that obey space-like or time-like evolution, and is developed for an arbitrary number of them, even if physical processes typically only require a few. Control of scale choices when more than one scale characterises a scattering process is also possible. We describe the technical details of the new representation of interpolation coefficients stored in the grid, and we demonstrate the capabilities of the library in a few phenomenological cases of interest. Specifically, we compute predictions for single-inclusive pion production in unpolarised and polarised proton-proton collisions and in semi-inclusive deep-inelastic scattering. We show how, in each case, PDF, FF, and scale uncertainties compare to each other and highlight the potential of PineAPPL as an essential ingredient for precision physics at current and future colliders.
hep-ph4 citations
04
$∣ V_{c b} ∣$ determinations from $B ˉ \to D^{(*)} ℓ ν ˉ$ decays within the SM and beyond
Wen-Sheng Fang🇨🇳 · Syuhei Iguro🇯🇵 · Xin-Qiang Li🇨🇳 · Ria Sain🇨🇳 · Ryoutaro Watanabe🇨🇳 · Ben-Liang Zhang🇨🇳
We investigate the $∣ V_{c b} ∣$ determinations from exclusive semi-leptonic $B ˉ \to D^{(*)} ℓ ν ˉ$ decays, together with comprehensive fit analyses of the $B ˉ \to D^{(*)}$ transition form-factors, by taking into account recent updates of experimental distribution data and theoretical evaluations. Several commonly adopted form-factor parameterizations, including BSZ, BGL and HQET, have been considered under different fit scenarios. We compare the fitted values and study how the $∣ V_{c b} ∣$ determinations depend on the form-factor parameterizations and on the treatment of the experimental inputs. In particular, we reproduce the official PDG average of $∣ V_{c b} ∣$ with the BGL parameterization, while the HQET parameterization tends to give a smaller value of $∣ V_{c b} ∣$ . We also consider new-physics effects that can contribute to $B ˉ \to D^{(*)} ℓ ν ˉ$ , and examine whether non-zero new-physics contributions are still allowed by the current data.
hep-ph1 citation
05
Freeze-in and ultra-relativistic freeze-out during general reheating scenarios
Kuldeep Deka🇦🇪
The dark-matter relic abundance can depend sensitively on the thermal history before radiation domination. We derive a general analytic framework for dark-matter production from the Standard Model bath during a non-instantaneous reheating era, unifying freeze-in, ultra-relativistic freeze-out and the approach to ordinary non-relativistic freeze-out. The reheating background is described by an effective equation-of-state parameter $ω$ and a cooling index $α$ , while the dark-matter interaction rate is parametrised by an effective scale $Λ$ and a leading temperature power $n$ . We show that the production history is organised by two critical temperature exponents: one controls whether a thermalised relativistic species decouples during reheating or after radiation domination begins, and the other controls whether post-decoupling production is infrared dominated, ultraviolet dominated or logarithmic. We derive analytic relic yields in the main regimes, including both the entropy-diluted freeze-out contribution and the post-freeze-out production term. These results explain the scaling of relic-density contours and are checked against numerical Boltzmann solutions. For matter-like reheating our framework reproduces the known IR/UV ultra-relativistic freeze-out structure, while more general reheating histories can shift the same microscopic interaction between freeze-in, ultra-relativistic freeze-out and ordinary freeze-out regimes.
hep-phastro-ph.CO1 citation
06
Scaling of the Surface Free Energy as a Probe of the QCD Critical Region
Joseph I. Kapusta🇺🇸 · Mayank Singh🇺🇸 · Shensong Wan🇺🇸
The QCD phase diagram is expected to have a critical point that separates the crossover and first-order transition lines. A realistic model that incorporates phase boundary effects is essential for heavy ion simulations to isolate the experimental signatures of a critical point. We discuss how to construct such an equation of state, and study its critical behavior. The effect of the coefficient of surface energy on the size of the critical region is investigated. We found that with this construction and with the chosen background equation of state, the temperature must be within one percent of its critical value to observe the critical exponents. This makes it doubtful that the critical exponents can be measured in heavy ion collisions, though it may still be feasible to observe signatures of a first-order phase transition. The method presented here is general and can be utilized with any given equation of state to test the viability of observing critical exponents in experiments.
hep-phnucl-th0 citations
07
Quantum decoherence of hyperon spin correlations in QCD hadronization
Feng Liu🇺🇸 · Zhoudunming Tu🇺🇸
Hadronization, the transition of quarks and gluons into hadrons, lies beyond the reach of perturbative quantum chromodynamics (QCD) and is commonly described by the semiclassical Lund string model. Yet this very success raises a fundamental question: where does the quantumness go during hadronization? In this Letter, we propose an approach inspired by quantum information science, in which (i) quark-antiquark pairs excited from the QCD vacuum inherit its quantum numbers, giving rise to spin entanglement at their creation, and (ii) subsequent string breaking generates environmental degrees of freedom that induce quantum decoherence of the spin state. This framework simultaneously describes the $Λ$ hyperon spin-correlation data measured at RHIC [Nature 650, 65-71 (2026)] and at the LHC, establishing a quantitative connection between the QCD vacuum, spin entanglement and decoherence, and hadronization.
hep-phhep-exnucl-exnucl-th3 citations
08
Fourier-Preconditioned Path Deformations for Multi-Field Vacuum Tunnelling
Suriyah R. Kannagi🇮🇳 · Aadarsh Singh🇮🇳 · Sudhir K Vempati🇮🇳
We present an endpoint-safe Fourier method for multi-field vacuum tunnelling. The field-space tunnelling path is written as a straight-line interpolation between the false and true vacua, plus sine-mode deformations that vanish at the endpoints. This gives a finite-dimensional path optimisation problem, which we implement using automatic differentiation in the JAX numerical framework. The method is studied both as a standalone variational ansatz for curved tunnelling paths and as a preconditioner for existing bounce solvers. On the OptiBounce benchmark potential for $N_{ϕ} = 3, \dots, 20$ and on a nested random-coefficient potential family up to $N_{ϕ} = 50$ , the Fourier result agrees with FindBounce, OptiBounce, and CosmoTransitions at the sub-percent level in the regular benchmark cases, while requiring only a modest number of modes. We also compare several endpoint-safe basis families and find that Fourier sine modes provide a robust default for smooth tunnelling paths. When used as an initialiser, the Fourier path supplies useful geometric information to existing solvers before the final bounce calculation is carried out. In the CosmoTransitions tests, this reduces the number of steps in subsequent path deformation, while in the FindBounce point-injection tests, it gives large runtime improvements in the high-dimensional cases up to 90 $%$ . These results suggest that endpoint-safe Fourier paths provide a useful bridge between simple analytic path ansätze and fully numerical multi-field bounce algorithms.
hep-phastro-ph.COgr-qchep-th0 citations
09
Search for a Time-Dependent Z' Resonance in the Dimuon Channel
Marlon P. Brade🇵🇭 · Jeremiah D. Juevesano🇵🇭 · Venus Abbegaile S. Carbonel · Karen E. Bustamante · Dennis C. Arogancia🇵🇭 · Jan Mickelle V. Maratas🇵🇭
We present a time-domain search strategy for resonances with periodically varying masses in high-energy collider data. Conventional resonance searches rely on time-integrated event samples and are therefore insensitive to signals whose properties evolve during data taking. To address this limitation, we develop a two-dimensional unbinned likelihood framework in invariant mass and time, allowing the reconstruction of signals that trace nontrivial trajectories in the $(m, t)$ plane rather than appearing as stationary resonances. As a benchmark scenario, we consider a $Z^{'}$ boson arising from a gauged $U (1)_{B - L}$ extension of the Standard Model and introduce a phenomenological model in which the mediator mass undergoes periodic temporal modulation. The resulting signal manifests as a resonance whose position changes with time, producing distinctive patterns that are inaccessible to conventional analyses based solely on invariant-mass information. The method is implemented using dimuon events from the CMS Open Data corresponding to the Run~G data-taking period at $s = 13 TeV$ , with an integrated luminosity of $7.54 fb^{- 1}$ . We derive upper limits on the gauge coupling $g^{'}$ as a function of the $Z^{'}$ mass for several choices of the modulation amplitude. The results demonstrate that incorporating temporal information can enhance sensitivity relative to standard time-integrated searches, particularly in regions with sufficient signal statistics.
hep-ph0 citations
10
Description of the process $e^{+} e^{-} \to π^{0} π^{0} γ$ in the extended NJL model
M.K. Volkov🇷🇺 · A.A. Pivovarov🇷🇺 · K. Nurlan🇷🇺
The cross section of the process $e^{+} e^{-} \to π^{0} π^{0} γ$ is calculated in the extended NJL quark model. The vector channel with the intermediate $ρ$ , $ω$ , $ρ^{'}$ and $ω^{'}$ mesons is considered. The main contribution is given by the intermediate radially excited $ρ^{'}$ meson. The role of the channel with the intermediate scalar meson is also discussed.
hep-ph0 citations
11
Semi-analytical results for $e^{+} e^{-} \to J / ψ + X_{non c c ˉ}$ up to $O (α_{s} v^{2})$ at B factories
Cong Li🇨🇳 · Hao-Yang Liu🇨🇳 · Xu-Dong Huang🇨🇳 · Wen-Long Sang🇨🇳
Within the NRQCD factorization framework, we investigate the color-singlet contribution to $e^{+} e^{-} \to J / ψ + X_{non c c ˉ}$ at B factories, computing the $O (α_{s})$ , $O (v^{2})$ , and $O (α_{s} v^{2})$ corrections to both the unpolarized cross section and the $J / ψ$ angular distribution. The $O (α_{s} v^{2})$ correction is obtained for the first time, and the validity of NRQCD factorization at this order is explicitly verified. Using the differential equation method, the short-distance coefficients are obtained as asymptotic expansions in $r = m_{c} / s$ up to $r^{40}$ , which reproduce exact results with high precision at B factory energies, achieving relative errors around $1 0^{- 14}$ for the cross section and around $1 0^{- 7}$ for the angular distribution. Notably, with the same input parameters, our $O (α_{s})$ and $O (v^{2})$ corrections are consistent with those reported in the literature. Phenomenologically, the $O (α_{s})$ correction (with $μ_{R} = s /2$ ) reaches about $50%$ of the leading-order cross section, while the $O (v^{2})$ and $O (α_{s} v^{2})$ corrections are accidentally small. After including feeddown contributions from $ψ (2 S)$ , the predicted cross section $0.53 0_{- 0.113}^{+ 0.122}$ pb agrees with the {\tt Belle} measurement within uncertainties. However, the predicted angular distribution parameter $0.12 0_{- 0.019}^{+ 0.027}$ deviates from the experimental value $5.71 \pm 2.51$ by more than $2 σ$ , calling for further experimental and theoretical investigations.
hep-phhep-ex2 citations
12
From target to projectile: CSS evolution of quark TMD in different light-cone gauges
Tolga Altinoluk🇵🇱 · Guillaume Beuf🇵🇱 · Jamal Jalilian-Marian🇺🇸 · Mirja Tevio🇫🇮
We calculate the one-loop corrections to the quark TMD in the projectile light-cone gauge using the background field formalism, with the Mandelstam-Leibbrandt (ML) prescription for the extra singularity present in the light-cone gauge propagator. We use the pure rapidity regulator for rapidity divergences. The Collins-Soper-Sterman (CSS) evolution equations are obtained after one-loop renormalization of the quark TMD in this gauge. We discuss how the structure of the rapidity divergences and the double-logarithmic contributions to the CSS resummation compares with the analogous calculation performed in the target light-cone gauge, and discuss the implications for the connection between the TMD factorization and Color Glass Condensate frameworks.
hep-ph0 citations
13
Ultra-High-Energy Cosmic Ray Boosted Relic Neutrinos
Jiajie Zhang🇨🇳 · Jiajun Liao🇨🇳
Ultra-high-energy cosmic rays (UHECRs) can boost relic neutrinos to high energies through Standard Model (SM) neutral-current interactions, providing an indirect probe of the cosmic neutrino background (C $ν$ B). In this work, we perform a systematic study of the diffuse UHECR-boosted C $ν$ B flux including elastic neutrino-nucleon scattering (ES), coherent elastic neutrino-nucleus scattering (COH), incoherent neutrino-nucleus scattering (INCOH), baryon-resonance production (RES), and deep inelastic scattering (DIS). For the UHECR flux, we use mixed-composition spectra obtained from the UHECR propagation code PriNCe and from the H3a and H4a implementations of the Hillas model, together with SFR, QSO and GRB source evolution models. We find a clear hierarchy of scattering channels in boosted neutrino energy. The coherent scattering dominates at low-energy neutrino flux for heavy nuclear component, while ES and INCOH become important once individual nucleons are resolved. The RES channel gives a non-negligible contribution in the high-energy region, and DIS appears only at the highest energies and is most visible for the H4a models. Using current IceCube and Pierre Auger Observatory data, we derive upper limits on the C $ν$ B overdensity. Our results show that reliable predictions of the UHECR-boosted C $ν$ B signal require a combined treatment of the relevant SM scattering channels, UHECR composition, source evolution and the neutrino mass spectrum.
hep-phastro-ph.HE0 citations
14
Twist-3 contributions to $γ γ \to π^{0} π^{0}, K_{S}^{0} K_{S}^{0}$ in $k_{T}$ factorization
Jun-Kang He🇨🇳 · Cong Wang🇨🇳
We compute the cross sections for the two-photon processes $γ γ \to π^{0} π^{0}$ and $γ γ \to K_{S}^{0} K_{S}^{0}$ in $k_{T}$ factorization, including the chirally enhanced two-parton twist-3 light-cone distribution amplitudes. For these charge-suppressed neutral channels the twist-3 cross sections exceed the twist-2 ones by close to an order of magnitude in the intermediate-energy region, bringing the predictions much closer to the Belle data, the residual underestimate being plausibly attributable to higher-order QCD corrections. The calculation reproduces the measured angular distributions and the energy dependence of the charged channels and the neutral pion, though not the steeper fall of the neutral kaon. The neutral-to-charged ratios are the most discriminating observables. They depend strongly on energy in the data, whereas our calculation, like other approaches in the literature, yields a nearly flat ratio. Finally, in a phenomenological discussion, we combine our contribution with the soft handbag contribution and largely reproduce the observed energy dependence, suggesting that the hard and soft contributions are comparably important in the few-GeV region.
hep-ph0 citations
15
Hidden-sectors search and probe of discrete symmetries at the REDTOP experiment
REDTOP COllaboration
The $η$ and $η^{'}$ mesons are nearly unique in the particle universe since they are nearly Goldstone bosons, and their decay dynamics are strongly constrained. While earlier experiments collected samples of order $\sim 1 0^{9}$ $η$ , the proposed REDTOP (Rare Eta Decays To Observe Physics Beyond the Standard Model) facility targets $O (1 0^{14})$ $η$ and $O (1 0^{12})$ $η^{'}$ , enabling broad searches for physics beyond the Standard Model. In this work, we present studies evaluating REDTOP sensitivity to processes that couple the Standard Model to New Physics through four portals: the Vector (dark photon), the Scalar (Higgs-mixing), the Axion-like, and the Heavy Lepton. In parallel, the proposed statistics allow precise tests of $C P$ and $T$ invariance and lepton universality and improve determinations of the $η / η^{'}$ transition form factors, which are crucial inputs to the hadronic light-by-light contribution to the muon anomalous magnetic moment $(g - 2)_{μ}$ .
↳ hep-exhep-ph1 citation
16
Galaxy-cluster-stacked Fermi-LAT, part IV: $\sim 70$ GeV WIMP annihilation lines
Uri Keshet🇮🇱
The strongest constraints on the velocity-dependent ( $p$ -wave) annihilation of weakly interacting massive particle (WIMP) dark matter were derived from the deep potential wells of galaxy clusters. Even weaker signals can be extracted from sufficient aggregated clusters, by cross-correlating $γ$ -rays with large-scale structure tracers or stacking over extensive cluster catalogs. Three independent such analyses show a similar triad of emission lines in Fermi-LAT data, around 70, 40, and 13 GeV, emerging from featureless spectra in each hemisphere upon cross-correlation with eROSITA maps, and in stacked MCXC, eROSITA, and DESI catalog clusters only once boosted to the cluster frame. These lines fit the anticipated $χχ \to γ γ$ , $γ Z$ , and $γ h$ annihilation channels of a $\sim 70$ GeV WIMP $χ$ , detected by composite matched filters at trial-corrected global $Z$ -scores reaching $5.6 σ$ (cross-correlations) and $2.3 σ$ (stacking), with intrinsic $\sim 1 0^{[- 20, - 19]}$ cm $^{3}$ s $^{- 1}$ channel cross-sections. High-resolution spectra establish six lines and an unresolved ( $2$ -- $3$ line) feature in total, naturally aligned with the anticipated nine channels of two cross-annihilating WIMPs of masses $67. 3_{- 0.1}^{+ 0.1}$ and $71. 4_{- 0.1}^{+ 0.2}$ GeV (profile-likelihood bounds; $_{- 5%}^{+ 3%}$ systematic; $5.3 σ$ ). The Galactic-center GeV excess is broadly consistent with the corresponding broad annihilation continuum.
↳ astro-ph.HEastro-ph.COhep-ph1 citation
17
Searching for axion dark matter conversion spectral lines in neutron star magnetospheres with FAST
Sinuo Gao🇨🇳 · Chen Wang🇨🇳 · Maoyuan Liu🇨🇳
The axion is a well-motivated dark matter candidate, which can convert into narrow radio spectral lines via the Primakoff effect in the strongly magnetized magnetospheres of neutron stars. This provides a novel astrophysical probe for axion searches that is complementary to laboratory experiments. Using FAST, the world's most sensitive single-dish radio telescope, we observed two X-ray dim isolated neutron stars (RXJ1605.3+3249 and RXJ1308.6+2127) within its sky coverage, which are predicted to yield the strongest axion-conversion spectral lines (ACL). Although no significant signal was detected at the 5 sigma confidence level, we establish new upper limits on the axion-photon coupling constant g_{a gamma gamma} less than or similar to 5 x 10^{-12} GeV^{-1} for axion masses ranging from 4.14 to 6.20 micro-eV corresponding to the 1.0-1.5 GHz observational band. This result constitutes the tightest constraint in this axion mass range among all existing studies employing the same ACL-based method.
↳ astro-ph.HEastro-ph.SRhep-ph1 citation
18
When Renormalisation Remembers: UV/IR Mixing as an Entanglement Bridge
Steven Abel🇬🇧
Renormalisation is traditionally understood to be a Wilsonian memoryless process in which ultraviolet (UV) degrees of freedom gradually decouple, leaving an autonomous infrared (IR) description. However this need not be the case: in UV/IR mixed theories correlations between widely separated scales can persist. In this work I recast UV/IR mixing as a Hilbert-space phenomenon, realised as correlations across renormalisation scales. This formulation is implemented using the Born-Reciprocal Tensor Network (BRTN), a new configuration of tensor network that is globally symmetric under phase-space reciprocity. On this network I prepare the vacuum and reproduce the expected radiative corrections. The resulting renormalisation geometry exhibits memory, with a bridge linking reciprocal representations of IR physics, whose cross-bridge entanglement provides a precise criterion for the viability of an effective description. I analyse when this criterion is met, and show that there is a large-volume limit, with the fundamental scale held fixed, in which the obstruction to a local description scales away: Wilsonian behaviour is restored and renormalisation forgets. The BRTN therefore provides a concrete and calculable platform for UV/IR mixing.
↳ hep-thhep-phquant-ph0 citations
19
Quantum Resources and Wigner Symmetry in Nucleon-Nucleon Scattering from Effective Field Theory
Ian Low🇺🇸 · Thomas R. Richardson🇺🇸 · Sokratis Trifinopoulos🇨🇭
We study quantum resources in the spin degrees of freedom, such as entanglement, stabilizer magic, and non-local magic, in low-energy nucleon-nucleon scattering through next-to-leading order in pionless effective field theory. Treating each nucleon spin as a qubit, we calculate the corresponding resource-generating powers of the scattering operator at generic center-of-mass momentum and scattering angle $Θ$ . The analysis retains $S$ - and $P$ -wave channels generated by two-derivative contact interactions. When the microscopic physics exhibits Wigner's $S U (4)$ spin-flavor symmetry, the neutron-proton amplitude becomes proportional to the spin-space identity operator and therefore generates no new resources after scattering, extending an observation previously made for leading-order $S$ -wave scattering. The same-nucleon channel remains resource-generating because constraints from identical particles project out part of the Hilbert space. These results show how enhanced symmetries, partial-wave structure, and resource generation are intertwined in low-energy two-body scattering.
↳ nucl-thhep-phquant-ph6 citations
20
Supersymmetric geometry in non-supersymmetric effective field theory
Nathaniel Craig🇺🇸 · Andrew Fee🇺🇸 · Yu-Tse Lee🇺🇸
We develop a geometric framework for non-supersymmetric effective gauge theories based on their nonlinear supersymmetrizations. We construct supersymmetric embeddings for most operators up to dimension six from constrained chiral and vector superfields, and formulate vector bundles using the superfields to systematically organize the operators under field redefinitions in the gauge sector. This formalism manifests a complex geometry underlying gauge operators and accommodates redefinitions across different spins.
↳ hep-thhep-ph1 citation
21
Tracing Ultra Light Axions in Post-reionization, Lyman- $α$ and CMB Missions
Debarun Paul🇮🇳 · Sourav Pal🇮🇳 · Amit Dutta Banik🇮🇳 · Supratik Pal🇮🇳
Ultra-light axions (ULAs) are dark matter candidates proposed to resolve the small scale anomalies of the standard cosmological model. Due to their inherent quantum pressure, ULAs result in a distinct, scale-dependent suppression on the matter power spectrum, which can leave imprints on the upcoming observations. We explore such possibilities by forecasting on the post-reionization large scale structure (LSS) surveys and next-generation cosmic microwave background (CMB) missions. By utilizing the cross-correlation between 21-cm intensity mapping (SKA1-MID and PUMA) and the Lyman- $α$ forest (DESI-like), we explore possible signatures of ULAs in post-reionization surveys while mitigating instrument-specific systematics. The Fisher matrix analysis projects uncertainties on the fractional ULA abundance across a wide ULA mass range of $1 0^{- 30} eV \leq m_{a} \leq 1 0^{- 20} eV$ , revealing an optimal detection sensitivity at intermediate masses around $m_{a} \sim 1 0^{- 25} eV$ . Furthermore, while next-generation CMB mission alone can yield small projected errors on the ULA fraction compared to future LSS missions, a joint analysis of the DESI-like and PUMA cross-spectrum alongside CMB-S4-like missions estimates an error on the ULA fraction to be $O (1 0^{- 4})$ for $m_{a} ≲ 1 0^{- 28}$ eV, highlighting a significant improvement over standalone LSS and CMB missions.
↳ astro-ph.COhep-ph0 citations
22
Effective-metric formulation of Casimir energies in nonlinear scalar and electromagnetic theories
C. A. Escobar🇲🇽
We study the Casimir effect in nonlinear field theories through the effective geometries that \mbox{govern} their linearized fluctuations. Previous analyses of Lorentz-violating scalar fields showed that a constant kinetic background modifies the parallel-plate Casimir energy by a rescaling of the plate separation and an overall determinant factor. We show that this structure is not merely a consequence of diagonalizing the reduced Green function. It follows from a common Schur-complement structure: after Fourier reduction parallel to the plates, the same reduced quadratic form controls the spectral denominator of the reduced Green function and the numerator generated by the energy-density insertion. This observation allows the Lorentz-violating scalar result to be used as an effective-metric prescription for regular fluctuation sectors arising from the linearization of nonlinear theories around constant backgrounds. In nonlinear scalar theories, the effective tensor is the Hessian of the Lagrangian evaluated on a constant-gradient background. In nonlinear electrodynamics $L (F)$ , a constant magnetic background splits the fluctuations into an ordinary Maxwell branch and an extraordinary optical branch. For this electromagnetic sector, we compute the parallel-plate Casimir energy both by direct mode summation and by applying the effective-metric formula branch by branch, finding exact agreement. The resulting energy depends on the orientation of the magnetic background relative to the plates, providing a concrete anisotropic Casimir response in a regular nonlinear electromagnetic sector.
↳ hep-thhep-phPRD(2026)·1 citation
23
Can a Slow and Strong Phase Transition in Neutron Stars Relieve Major Compact-Star Observation Tensions?
Chen Zhang🇨🇳
Recent anomalous compact-star observations challenge the conventional neutron-star interpretation in complementary ways: HESS J1731--347 and XTE J1814--338 favor unusually small radii at low mass, while the secondary component of GW190814 appears too massive for an ordinary neutron star under GW170817-based maximum-mass inferences. We examine whether neutron stars with a strong first-order hadron--quark phase transition can address these tensions via the extended stable hybrid branches that arise when the phase conversion is slow compared to radial oscillations, while remaining consistent with GW170817 and NICER constraints. Using a piecewise-polytropic (PP) benchmark, supplemented by an independent speed-of-sound (CS) parametrization comparison, we find two viable patterns in a general parameter scan over both the hadronic and hybrid branches. Scenario 1 realizes an all-at-once solution: the same EOS has a pure hadronic branch compatible with both the GW190814-scale mass and HESS J1731--347, while its slow stable hybrid branch reaches XTE J1814--338. Scenario 2 retains the GW190814-scale hadronic branch but reaches XTE J1814--338 and HESS J1731--347 on slow stable branches in different transition-strength regimes.
↳ astro-ph.HEgr-qchep-phnucl-th2 citations
24
Synergy between CSST and future gravitational-wave detectors: Probing primordial black holes by cross-correlating dark sirens with galaxies
Ya-Nan Du🇨🇳 · Ji-Yu Song🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳
Gravitational-wave (GW) events and galaxies both trace the cosmic matter distribution, but the mergers of astrophysical black holes and primordial black holes (PBHs) are expected to populate different environments and therefore to cluster with different biases. The GW clustering bias is thus a statistical observable that can separate the two populations. We assess how well this can be done by cross-correlating the photometric galaxy survey of the Chinese Space-station Survey Telescope (CSST) with mock GW catalogs from two future detector networks: the third-generation ET2CE network (the Einstein Telescope and two Cosmic Explorer detectors) and the multi-band BDET2CE network, which adds the space-based baseline Decihertz Interferometer Gravitational-Wave Observatory. We find that CSST combined with 10 years of ET2CE observations can reveal a PBH contribution once its fraction in the total merger rate exceeds about $40%$ , while the much sharper sky localization of BDET2CE lowers this threshold to about $20%$ . The improvement comes from recovering the small-scale clustering information that localization errors would otherwise erase. These results show that combining future GW detector networks with CSST galaxy clustering offers a promising and largely independent route to identifying PBHs statistically.
↳ astro-ph.COastro-ph.GAgr-qchep-ph1 citation
25
Hamiltonian formalism for Bose excitations in a plasma with a non-Abelian interaction: plasmon bremsstrahlung
Yu.A. Markov🇷🇺 · M.A. Markova🇳🇴 · N.Yu. Markov🇷🇺
The classical Hamiltonian wave theory describing plasmon bremsstrahlung radiation occurring upon collision of high-energy color-charged particles in a hot quark-gluon plasma is proposed. A generalization of the Lie-Poisson bracket to the case of a hot QCD medium, involving two independent components $a_{k}^{* (1) a}$ and $a_{k}^{* (2) a}$ of the bosonic normal field variable $a_{k}^{* a}$ and two non-Abelian color charges $Q_{1}^{a}$ and $Q_{2}^{a}$ is suggested. The canonical transformations including both bosonic degrees of freedom of the soft collective excitations of the hot quark-gluon plasma and degrees of freedom of two hard test particles related to their color charges are written out. The most general structure of the canonical transformations in the form of integro-power series in the components $c_{k}^{* (α) a}, α = 1, 2$ , of the new normal field variable $c_{k}^{a}$ and in the new color charges $Q_{α}^{a}$ up to the terms of sixth order is presented. To construct kinetic equations the multiple-time-scale perturbation theory is used. The notion of the plasmon number density $N_{k}^{(α, α^{'}) a a_{1}^{'}} (τ)$ , which is a nontrivial matrix both in the effective color space and in effective two-particle space, is introduced. The self-consistent system of four Boltzmann-type kinetic equations taking into account the time evolution of the averaged color charges of the hard particles is obtained. In the approximation of the fixed color charges of two interacting particles the exact solution of the system of kinetic equations defining the dynamics of the colorless $N_{k}^{(1)}$ , $W_{k}^{(1)}$ and color $N_{k}^{(2)}$ , $W_{k}^{(2)}$ components of the plasmon number density, is obtained.
↳ hep-thhep-ph0 citations
26
A Double--Scaling Large--$d$ Saddle of BFSS/BMN Matrix Quantum Mechanics
Badis Ydri🇩🇿
We study the large--$d$ dynamics of the mass--deformed bosonic $\mathrm{BFSS}_{d+1}$ matrix quantum mechanics using a Hubbard--Stratonovich localization of the Yang--Mills interaction. After integrating out the matrix coordinates, the theory reduces to a holonomy--dependent effective action for an auxiliary adjoint kernel. We introduce a commuting--symmetric saddle and its maximally symmetric specialization, in which the interaction is encoded in a single dynamically generated mass shift $k_0$. The resulting large--$d$ description is a gauged matrix harmonic oscillator with self--consistent frequency $s^2=m+k_0$, fixed by a gap equation. We analyze the low--temperature $X$-space physics, the holonomy effective action, the Yang--Mills observable, and the associated phase structure. We then identify a correlated double--scaling limit in which $d\to\infty$, $m\to\infty$, and $\kappa=m^{3/2}/d$ is held fixed. In this limit the Yang--Mills interaction and the explicit mass deformation remain parametrically balanced: the theory interpolates between the commutator--dominated BFSS regime and the mass--dominated Gaussian regime. The double--scaled theory exhibits two complementary large--$d$ regimes. At low temperature, the enhanced gap pushes the deconfinement scale upward and opens a parametrically large uniform--holonomy region, where the bulk dynamics behaves as weakly coupled $\mathrm{BFSS}_2$--type gauged harmonic--oscillator sectors. At the same time, the high--temperature branch reveals an overlap window in which the Gaussian description remains self--consistent while the commutator contribution per matrix pair is parametrically suppressed. The resulting dynamics is therefore $\mathrm{BFSS}_2$--like in its enlarged uniform--holonomy sector and IKKT--like in its almost--commuting matrix behavior.
↳ hep-thgr-qchep-lathep-ph+22 citations
27
Effective description of lensed gravitational waves diffracted by stellar fields
Miguel Zumalacárregui🇩🇪 · Xikai Shan🇨🇳
As natural telescopes, Gravitational lenses enable the observation of sources that would otherwise be too distant and faint. Stellar-mass objects, or microlenses, act as impurities in the lens, producing subtle distortions of the source. These effects are necessary to correctly interpret observations, and may in some cases be themselves evidence of gravitational magnification. Gravitational waves (GWs) observed by ground detectors and magnified by galaxies and clusters will undergo microlensing by fields of stars and remnants: describing these systems requires not only considering a large number of small-scale lenses (microlenses), but also including wave-optics effects, leading to frequency dependent modulations of the signal. Here we present novel models for Reduced-Order Stochastic Diffraction (ROSD), which overcome these challenges in the search for GW lensing signatures: an effective description is synthesized from numerical simulations of wave-optics lensing by stellar fields via a singular value decomposition. The procedure yields an optimized orthonormal basis to describe microlensing distortions and a probability density function for the coefficients, which can be used as priors or to verify the consistency with stellar-field lensing. We present SVD-stellar-I5-aLIGO as an example of this model category, discuss the role of truncation order and demonstrate how it can be applied to GW data via injection and recovery in Bayesian parameter estimation. ROSD can be tailored to account for detector sensitivity and the type of source under analysis, and extended to different microlens populations and external potentials. ROSD models open a new window to probe small-scale objects (stars, remnants and potentially dark matter) and facilitate the discovery of the most distant compact binary mergers.
↳ astro-ph.HEastro-ph.COastro-ph.GAgr-qc+16 citations
28
Constraints on the Sum of Neutrino Masses from ACT DR6 and DESI DR2 Considering Isocurvature Initial Conditions
Hongsheng Hou🇨🇳 · Sai Wang🇨🇳 · Zhi-Chao Zhao🇨🇳 · Xin Zhang🇨🇳
We present a robust assessment of cosmological constraints on the sum of neutrino masses ( $\sum m_{ν}$ ) when relaxing the standard assumption of purely adiabatic primordial initial conditions. Allowing for a neutrino density isocurvature (NDI) component alongside the adiabatic mode, we analyse the latest CMB-SPA combination (Planck 2018, ACT DR6, and SPT-3G), DESI DR2 baryon acoustic oscillation data, and the DES Year 5 supernova sample. Within the $Λ$ CDM model, the 95\% upper limit weakens only marginally from $\sum m_{ν} < 0.052$ eV (purely adiabatic) to $< 0.057$ eV (including NDI), with the NDI amplitude consistent with zero. In the CPL dynamical dark energy model, the adiabatic limit is $< 0.111$ eV, shifting to $< 0.115$ eV with NDI, yet the isocurvature mode remains undetected. While these limits are robust against the inclusion of isocurvature perturbations, they are highly sensitive to both the assumed dark energy equation of state and the prior lower bound on $\sum m_{ν}$ . Notably, the adiabatic $Λ$ CDM limit of $0.052$ eV lies below the minimum sum required by the normal neutrino mass hierarchy ( $0.05878$ eV), indicating that this bound is an artifact of the statistical prior extending to zero. Imposing a physically motivated hierarchy-informed prior raises the limit to $< 0.092$ eV. Our results demonstrate that current data show no evidence for NDI modes and that the inferred neutrino mass upper limit is robust against this extension, but a definitive, model-independent bound requires addressing prior dependencies and dark energy uncertainties. This work provides the first joint constraint on $\sum m_{ν}$ and NDI using the full CMB-SPA+DESI DR2+DES dataset.
↳ astro-ph.COgr-qchep-ph2 citations
29
Perturbative QCD as a quantitative tool in the years 1976-2000
R Keith Ellis🇬🇧
This paper traces the development of precision QCD in the years 1976-2000.This is after the discovery of asymptotic freedom, and after the exploration of the simplest processes based on the operator product expansion. The new theoretical tools of factorization, infra-red safety andresummation, needed to make predictions for the colliding beam machines of this era, are described. The role of computer algebra and modern spinor techniques for the calculation of amplitudes and cross sections are briefly reviewed. A selection of important processes calculated at next-to-leading order (or in limited cases beyond next-to-leading order) is presented.
↳ physics.hist-phhep-ph0 citations
30
Pushing the Primordial Frontier: Exact Linear Solutions in Multifield Inflation
Javier Huenupi🇺🇸 · Claudio Muñoz🇨🇱 · Gonzalo A. Palma🇨🇱 · Spyros Sypsas🇨🇱
We present exact analytic solutions for the linear dynamics of a two-field inflationary system in which the primordial curvature perturbation $ζ$ is coupled to an isocurvature perturbation $σ$ of entropy mass $μ$ . The solutions are valid for arbitrary values of $μ$ and the dimensionless interaction strength $λ$ , within a quasi-de Sitter background. They therefore provide analytic control over the strong mixing regime in which $ζ$ interacts with light isocurvature fields, commonly associated with rapid-turn inflation. As a first application, we derive the amplitude of the primordial power spectrum in closed form, obtaining an expression that interpolates between the weakly mixed, strongly mixed, light-field, and heavy-field regimes. These results open the way to analytic studies of multifield observables beyond the power spectrum, including non-Gaussianity, particle production, and loop corrections.
↳ astro-ph.COhep-phhep-th6 citations

Affiliations

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