HEP Phenomenology·hep-ph

Tue·Oct 22, 2024Tuesday·October 22, 2024

46 papers—32 primary·14 cross-listed·reconstructed*

01*
Axion effects on gamma-ray spectral irregularities. II: Implications of EBL absorption
Hai-Jun Li🇨🇳 · Wei Chao🇨🇳 · Xiu-Hui Tan🇨🇳 · Yu-Feng Zhou🇨🇳
The extragalactic background light (EBL) plays a crucial role in the propagation of high-energy particles throughout the Universe. In this work, we explore the impact of the EBL absorption effect on photon to axionlike particle (ALP) conversions from the very-high-energy gamma-ray spectral irregularities. For our purpose, we select four BL Lac blazars: Markarian 501, 1ES 0229+200, PKS 0301-243, and PKS 0447-439 for analysis. Their redshifts range from approximately 0.03 to 0.34. We first discuss the EBL absorption effect on the gamma-ray spectral energy distributions (SEDs) using three common EBL spectral models: Finke-10, Franceschini-17, and Saldana-Lopez-21. Then we consider the photon-ALP conversions in astrophysical magnetic fields. The best-fit chi-square distributions of these EBL models under the ALP assumption in the ALP parameter ${m_{a}, g_{aγ}}$ plane are provided, showing similar distributions. For comparison, we define a new delta chi-square, $χ_{d}^{2}$ , to quantify the difference in chi-square values. The distributions of $χ_{d}^{2}$ and the gamma-ray SEDs corresponding to the maximum delta chi-square, $χ_{d, max}^{2}$ , are also presented for comparison. Our results indicate that the influence of these different EBL models is non-dominant at the low-redshift gamma-ray axionscope. In these cases, choosing the latest model, Saldana-Lopez-21, is sufficient. However, as the redshift of the sources increases, this influence becomes more significant.
hep-phastro-ph.HEPLB(2025)·3 citations
02*
Type-II Seesaw Higgs triplet productions and decays at the LHC
Otilia A. Ducu (1)🇷🇴 · Ana E. Dumitriu (1)🇷🇴 · Adam Jinaru (1)🇷🇴 · Romain Kukla🇫🇷 · Emmanuel Monnier (2)🇫🇷 · Gilbert Moultaka (3)🇫🇷 · Alexandra Tudorache (1)🇷🇴 · Hanlin Xu (4) ((1) IFIN-HH Bucharest, Romania, (2) CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France, (3) Laboratoire Univers & Particules de Montpellier (LUPM), Université de Montpellier, CNRS, Montpellier, France, (4) Department of Modern Physics and State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei, China)🇨🇳
The Type-II Seesaw Model provides an attractive scenario to account for Majorana-neutrino masses. Its extended Higgs sector, if sufficiently light, can have a rich and distinctive phenomenology at the LHC while yielding automatically an essentially Standard-Model-Higgs-like state. Several phenomenological studies have been devoted to the scalar sector of this model, as well as experimental searches focusing mostly on the (doubly-)charged states. In this paper we present an exhaustive study of the main production and decay channels of all the non-standard scalar states originating from the $S U (2)_{L}$ doublet and a complex triplet of the model. We stick to scenarios where lepton-number-violating decays are suppressed, for which present experimental limits are still weak, highlighting theoretical parameter sensitivities that were not previously emphasized in the literature and the uncertainties they can induce for the experimental searches at the LHC. A comprehensive classification of the various cascade decays and corresponding Standard Model particle multiplicities is provided. As an illustration, a detailed prospective search study at the LHC with an ATLAS-like detector is carried out on some benchmark points, for charged, doubly-charged, and, for the first time, neutral state productions
hep-phJHEP(2025)·8 citations
03*
A systematical study of the nucleon form factors with the pion cloud effect
Jiaqi Wang🇨🇳 · Dongyan Fu🇨🇳 · Yubing Dong🇨🇳
The electromagnetic and gravitational form factors of the nucleon are studied simultaneously using a covariant quark-diquark approach, and the pion cloud effect on the form factors is explicitly discussed. In this study, the electromagnetic form factors are calculated to determine the parameters of our approach. Then, the gravitational form factors of the nucleon are evaluated with the same parameters. The electromagnetic and mechanical properties, such as charge radii, magnetic moments, and mass radii are presented. Moreover, the D-term, which is believed to be connected with the internal force inside the nucleon, is also discussed in this paper. Our results are in reasonable agreement with the experimental and lattice results, and it is suggested that the pion cloud contribution plays an indispensable role, especially for the magnetic moments and the sign of D-term.
hep-phEPJC(2025)·10 citations
04*
Beauty hadron production in high energy proton-proton and heavy-ion collisions in the EPOS4HQ framework
J. Zhao🇩🇪 · J. Aichelin🇫🇷 · P.B. Gossiaux🇫🇷 · K. Werner🇫🇷
Charmed hadron observables from the RHIC to LHC energies have been very successfully described with the recently advanced EPOS4HQ event generator. Here we extend this investigation to the production of beauty hadrons in proton-proton (pp) and heavy ion (HI) collisions
hep-phnucl-thPoS(2025)·1 citation
05*
Pushing the Heavy Quark Expansion for $b \to c l ν ˉ$ to Higher Order in $1/ m_{b}$
Ilija S. Milutin🇩🇪 · Thomas Mannel🇩🇪 · K. Keri Vos🇳🇱
The Heavy Quark Expansion (HQE) is the major tool to perform calculations for inclusive semileptonic $B \to X_{c} l ν ˉ$ and, consequently, for precision determinations of the CKM matrix element $V_{c b}$ . To further improve precision, we pushed the expansion to $1/ m_{b}^{5}$ to include even higher order terms in the HQE. Notably, at $1/ m_{b}^{5}$ , ``intrinsic charm'' (IC) contributions proportional to $1/ (m_{b}^{3} m_{c}^{2})$ occur, which are numerically expected to be sizeable. We will therefore firstly discuss the determination of a reduced set of HQE parameters at $1/ m_{b}^{5}$ , employing Reparametrisation Invariance (RPI) to this end. Consequently, we will show how the IC and ``genuine" $1/ m_{b}^{5}$ contribute to the different kinematical moments of $B \to X_{c} l ν ˉ$ , focusing in this work on the lepton energy $E_{l}$ moments. Using the ``lowest-lying state saturation ansatz'' (LLSA), we estimate the size of these contributions and observe a partial cancellation between the IC and ``genuine'' $1/ m_{b}^{5}$ contributions, leading to an overall small contribution.
hep-phPoS(2025)·2 citations
06*
Spectroscopic Properties of Double-Strangeness Molecular Tetraquarks
Fu-Lai Wang🇨🇳 · Si-Qiang Luo🇨🇳 · Ri-Qing Qian🇨🇳 · Xiang Liu🇨🇳
Inspired by recent advances in the study of the $K^{(*)} K ˉ^{(*)}$ molecular tetraquarks and the $H$ -dibaryon, we focus on the spectroscopic properties of the $K ˉ^{(*)} K ˉ^{(*)}$ systems, which exhibit exotic flavor quantum number of $ss q ˉ q ˉ$ . A dynamical analysis is performed using the one-boson-exchange model to describe the effective interactions for these systems, accounting for both $S$ - $D$ wave mixing and coupled-channel effects. By solving the coupled-channel Schr $o ¨$ dinger equation, we identify the $I (J^{P}) = 0 (1^{+})$ $K ˉ K ˉ^{*}$ and $I (J^{P}) = 0 (1^{+})$ $K ˉ^{*} K ˉ^{*}$ states as the most likely candidates for double-strangeness molecular tetraquarks. Furthermore, we estimate their strong decay behaviors based on the effective Lagrangian approach, with several channels exhibiting considerable decay widths. Meanwhile, we investigate their magnetic moments and M1 radiative decay widths, shedding light on their inner structures, within the constituent quark model. Finally, we encourage experimentalists to focus on these predicted double-strangeness molecular tetraquark candidates, particularly in $B$ meson decays. Such efforts could pave the way for establishing the molecular tetraquark states in the light-quark sector.
hep-phhep-exhep-latPRD(2024)·9 citations
07*
Chromopolarizability of charm-beauty quarkonium from $B_{c} (2 S) \to B_{c} π π$ transition
Yun-Hua Chen🇨🇳 · Zi-Wei Li🇨🇳
The chromopolarizability of a charm-beauty quarkonium characterizes its interaction with soft gluonic fields and can be probed through heavy quarkonium decays. Using the dispersion theory which considers the $π π$ final state interaction model-independently, we analyze the transition $B_{c} (2 S) \to B_{c} π^{+} π^{-}$ and determine the chromopolarizability $α_{B_{c} (2 S) B_{c}} = (0.66 \pm 0.25)$ GeV $^{- 3}$ and the parameter $κ = - 0.02 \pm 0.13$ . Our results indicate that the transitional chromopolarizability of the $c b ˉ$ state lies between the transitional chromopolarizabilities of the $c c ˉ$ and $b b ˉ$ states. These findings provide valuable insights into the interactions of charm-beauty quarkonium with light hadrons.
hep-phCommun.Theor.Phys.(2025)·0 citations
08*
Three-loop ladder diagrams with two off-shell legs
Ming-Ming Long🇩🇪
We present an analytic calculation of three-loop four-point Feynman integrals with two off-shell legs of equal mass. We provide solutions to the canonical differential equations of two integral families in both Euclidean and physical regions. They are validated numerically against independent computations. A total of 170 master integrals are expressed in terms of multiple polylogarithms up to weight six. Most of them are computed for the first time. Our results are essential ingredients of the scattering amplitudes for equal-mass diboson production at next-to-next-to-next-to-leading-order QCD at the LHC.
hep-phJHEP(2025)·10 citations
09*
Flavor-changing phenomenology in a $U (1)$ model
N. T. Duy🇻🇳 · D. T. Huong🇻🇳 · Duong Van Loi🇻🇳 · Phung Van Dong🇻🇳
We investigate a family-nonuniversal Abelian extension of hypercharge, which significantly alters the phenomenological features of the standard model. Anomaly cancellation requires that the third quark family transforms differently from the first two quark families. Additionally, it acquires that three right-handed neutrinos are presented. This model generates naturally small neutrino masses and a $W$ -boson mass deviation appropriate to recent measurements. Additionally, the model introduces flavor-changing neutral currents (FCNCs) of quarks coupled to the new gauge boson $Z^{'}$ and new Higgs fields. These FCNCs significantly modify the neutral-meson mixing amplitudes and rare meson decays, which are studied in detail. We also address flavor changing processes in the charged lepton sector.
hep-phEPJC(2025)·4 citations
10*
Probing the onset of hydrodynamization in peripheral p-Pb collisions at $s_{N N} =$ 5.02 TeV
Nikhil Hatwar🇮🇳 · Sadhana Dash🇮🇳 · Basanta Kumar Nandi🇮🇳
An attempt has been made to estimate the minimum size of the de-confined matter of Quark-Gluon Plasma (QGP) in small systems like p-Pb system that could be satisfactorily modeled with low-order hydrodynamics. The variation of second order transport coefficient of second order relativistic viscous hydrodynamics, the shear relaxation time has been utilized to study the sensitivity of experimental observables like elliptic flow coefficient. A representative system of p-Pb collisions at $s_{N N} =$ 5.02 TeV, simulated with the state-of-art framework of JETSCAPE event generator was used to study the variation of elliptic flow coefficient for peripheral collisions. The soft sector dynamics was simulated using an initial condition, a pre-equilibrium stage, hydrodynamics and a hadron afterburner. The transverse momentum spectra and rapidity distribution was obtained for light flavored hadrons and compared with the experimental data. The increase in elliptic flow fluctuations indicate breakdown of fluid behavior at $d N / d y \approx 14$ for p-Pb collision at $s_{N N} =$ 5.02 TeV.
hep-phnucl-th1 citation
11*
Lyman- $α$ limit on axion-like cold dark matter
Zixuan Xu🇨🇳 · Sibo Zheng🇨🇳
Using low redshift data on astrophysical reionization, we report new Lyman- $α$ limit on axion-like particle (ALP) as cold dark matter in ALP mass range of $m_{a} \sim 30 - 1000$ eV. Compared to the Leo T and soft-X ray bound, this limit is so far the most stringent in the ALP mass range of $m_{a} \sim 375 - 425$ eV and complementary in the ALP mass range otherwise. Combing these limits, we show new exclusion limits on $m_{a}$ for the ALP DM from either misalignment or freeze-in mechanism.
hep-phastro-ph.COPRD(2025)·5 citations
12*
Kaons and antikaons in isospin asymmetric dense resonance matter at finite temperature
Manpreet Kaur🇮🇳 · Arvind Kumar🇮🇳
We study the in-medium properties of kaons and antikaons in isospin asymmetric hot and dense resonance matter within the chiral SU(3) hadronic mean field model. Along with nucleons and hyperons, the interactions of $K$ and $K ˉ$ mesons with all decuplet baryons ( $Δ^{++, +, 0, -}, Σ^{*\pm, 0}, Ξ^{* 0, -}, Ω^{-}$ ) are explicitly considered in the dispersion relations. The properties of mesons in the chiral SU(3) model are modified at finite density and temperature of asymmetric resonance matter through the exchange of scalar fields $σ, ζ$ and $δ$ and the vector fields $ω, ρ$ and $ϕ$ . The presence of resonance baryons in the medium at finite temperature is observed to modify significantly the effective masses of $K$ and $K ˉ$ mesons. We also calculated the optical potentials of kaons and antikaons as a function of momentum in resonance matter. The present study of in-medium masses and optical potentials of kaons and antikaons will be important for understanding the experimental observables from the heavy-ion collision experiments where hot and dense matter may be produced. Our results indicate that when resonance baryons are present within the medium at finite baryonic density, the mass reduction of kaons and antikaons becomes more pronounced as the temperature of the medium increases from zero to 100 and 150 MeV. The study of the optical potentials of kaons and antikaons reveals a stronger correlation with strangeness fraction compared to isospin asymmetry.
hep-phnucl-thPRD(2024)·9 citations
13*
Non-thermal production of Higgsino dark matter by late-decaying scalar fields
Hajime Fukuda🇯🇵 · Qiang Li🇯🇵 · Takeo Moroi🇯🇵 · Atsuya Niki🇯🇵
We study the non-thermal production of the Higgsino dark matter (DM). Assuming that the lightest neutral Higgsino is the lightest supersymmetric particle (LSP) in minimal supersymmetric standard model, we calculate the relic abundance of the Higgsino LSP produced by the decay of late-decaying scalar field. In the calculation of the relic abundance, we have properly included the effects of coannihilation as well as the non-perturbative effect (known as the Sommerfeld effect). Contrary to the case of the thermal-relic scenario, in which the observed DM abundance is realized with the Higgsino mass of ~ 1.2 TeV, Higgsino DM is possible with lighter Higgsino mass as the reheating temperature becomes lower than the Higgsino mass. The reheating temperature relevant for realizing the correct DM density is presented as a funciton of the Higgsino mass.
hep-phJHEP(2025)·6 citations
14*
Analysis of beyond the Standard Model resonances with effective approaches and oblique parameters
Ignasi Rosell🇪🇸 · Antonio Pich🇪🇸 · Juan Jose Sanz-Cillero🇪🇸
Experiments have confirmed the presence of a mass gap between the Standard Model and potential New Physics. Consequently, the exploration of effective field theories to detect signals indicative of Physics Beyond the Standard Model is of great interest. In this study, we examine a non-linear realization of the electroweak symmetry breaking, wherein the Higgs is a singlet with independent couplings, and Standard Model fields are additionally coupled to heavy bosonic resonances. We present a next-to-leading-order determination of the oblique $S$ and $T$ parameters. Comparing our predictions with experimental values allows us to impose constraints on resonance masses, requiring them to exceed the TeV scale ( $M_{R} > 2$ TeV). This finding aligns with our earlier analysis, employing a less generalized approach and the experimental bounds of that time, where we computed these observables.
hep-phPoS(2025)·0 citations
15*
Virtual corrections to top-pair production from new physics
Simone Tentori🇧🇪
New physics and SM parameters can be studied and constrained by looking at the modifications to top-pair differential kinematical distributions due to off-shell effects. I present here three case studies: the determination of the Higgs couplings to the top-quark, a search for generic BSM scalar and pseudoscalar states, and a search for Axion Like Particles (ALP). The corresponding models have been implemented in the $UFO$ format to allow automatic computations within MadGraph5_aMC@NLO.
hep-phhep-exPoS(2025)·0 citations
16*
Verifying the Resonance Schemes of Unstable Particles at Lepton Colliders
Shao-Feng Ge🇨🇳 · Ui Min🇨🇳 · Zhuoni Qian🇨🇳
We propose practical ways of differentiating the various (Breit-Wigner, theoretical, and energy-dependent) resonance schemes of unstable particles at lepton colliders. First, the energy-dependent scheme can be distinguished from the other two by fitting the $Z$ lineshape scan and forward-backward asymmetries at LEP and future lepton colliders with the $Z$ mass $m_{Z}$ , decay width $Γ_{Z}$ , and coupling strength as fitting parameters. Although the Breit-Wigner and theoretical schemes work equally well, the scheme conversion requires the decay width $Γ_{Z}$ to scale inversely with $m_{Z}$ rather than the usual linear dependence from theoretical calculation. These contradicting behaviors can be used to distinguish the Breit-Wigner and theoretical schemes by the precision $Z$ measurements with single parameter ( $m_{Z}$ ) fit at future lepton colliders. For the $W W$ threshold scan, its combination with the precise Fermi constant provides another way of distinguishing the Breit-Wigner and theoretical schemes.
hep-phhep-exPLB(2025)·1 citation
17*
Exploring multi-step electroweak phase transitions in the 2HDM+ $a$
Zong-guo Si🇨🇳 · Hong-xin Wang🇨🇳 · Lei Wang🇨🇳 · Yang Zhang🇨🇳
Multiple electroweak phase transitions occurring sequentially in the early universe can give rise to intriguing phenomenology, compared to the typical single-step electroweak phase transition. In this work, we investigate this scenario within the framework of the two-Higgs-doublet model with a pseudoscalar, utilizing the complete one-loop finite-temperature effective potential. After considering relevant experimental and theoretical constraints, we identify four distinct types of phase transitions. In the first case, only the configuration of the CP-even Higgs acquires a non-zero value via a first-order or a cross-over electroweak phase transition, leading to electroweak symmetry breaking. In the remaining three cases, the pseudoscalar fields can obtain vacuum expectation values at different phases of the multi-step phase transition process, leading to spontaneous breaking of the CP symmetry. As the temperature decreases, the phase shifts to the vacuum observed today via first-order electroweak phase transition, at this point, the vacuum expectation value of the pseudoscalar field returns to zero, restoring the CP symmetry. Finally, we compare the transition strength and the stochastic gravitational wave background generated in the four situations along with the projected detection limits.
hep-phEPJC(2025)·7 citations
18*
Constraints on new physics couplings from $B ˉ \to D^{*} (D π) ℓ ν ˉ_{ℓ}$ angular analysis
Nicola Losacco🇮🇹
The Belle Collaboration has measured the complete set of angular coefficient functions for the decays $B ˉ \to D^{*} (D π) ℓ ν ˉ_{ℓ}$ , where $ℓ = e, μ$ , in four bins of the variable $w = \frac{m _{B}^{2} + m _{D^{*}}^{2} - q ^{2}}{2 m _{B} m _{D^{*}}}$ , with $q$ the momentum of the lepton pair. In SM this measurement is instrumental in determining the hadronic form factors in the $B \to D^{*}$ matrix elements of the SM weak current, thereby refining the measurement of $∣ V_{c b} ∣$ . On the other hand, it can be used to assess the impact of possible new physics contributions. I consider an extension of the SM effective Hamiltonian that governs this mode, incorporating the complete set of Lorentz invariant $d = 6$ operators compatible with the gauge symmetry of the theory. The measured angular coefficient functions play a pivotal role in constraining the couplings in the generalized effective Hamiltonian.
hep-phPoS(2025)·0 citations
19*
The $Λ_{c}^{+} \to η π^{+} Λ$ reaction and the $Λ a_{0}^{+} (980)$ and $π^{+} Λ (1670)$ contributions
Man-Yu Duan🇨🇳 · Wen-Tao Lyu🇨🇳 · Chu-Wen Xiao🇨🇳 · En Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Dian-Yong Chen🇨🇳 · Eulogio Oset🇪🇸
We study from the theoretical point of view the $Λ_{c}^{+} \to π^{+} η Λ$ reaction, recently measured by the Belle and BESIII Collaborations, where clear signals are observed for $a_{0} (980)$ , $Λ (1670)$ , and $Σ (1385)$ excitation. By considering the $a_{0} (980)$ and $Λ (1670)$ as dynamically generated resonances from the meson meson and meson baryon interaction, respectively, we are able to determine their relative production strength in the reaction, which is also tied to the strength of the $π^{+} η Λ$ tree level contribution. We observe that this latter strength is very big and there are large destructive interferences between the tree level and the rescattering terms where the $a_{0} (980)$ and $Λ (1670)$ are generated. The $Σ (1385)$ contribution is included by means of a free parameter, the only one of the theory, up to a global normalization, when one considers only external emission, and we observe that the spin flip part of this term, usually ignored in theoretical and experimental works, plays an important role determining the shape of the mass distributions. Internal emission is also considered and it is found to play a minor role.
hep-phhep-exPRD(2025)·17 citations
20*
Maximally entangled gluons for any $x$
Yoshitaka Hatta🇺🇸 · Jake Montgomery🇺🇸
Individual quarks and gluons at small- $x$ inside an unpolarized hadron can be regarded as Bell states in which qubits in the spin and orbital angular momentum spaces are maximally entangled. Using the machinery of quantum information science, we generalize this observation to all values $0 < x < 1$ and describe gluons (but not quarks) as maximally entangled states between a qubit and a qudit. We introduce the conditional probability distribution $P (l^{z} ∣ s^{z})$ of a gluon's orbital angular momentum $l^{z}$ given its helicity $s^{z}$ . Restricting to the three states $l^{z} = 0, \pm 1$ , which constitute a qutrit, we explicitly compute $P$ as a function of $x$
hep-phquant-phPRD(2025)·20 citations
21*
Reconciling the kinematical constraint with the JIMWLK evolution equation: correlation functions non-local in rapidity
Piotr Korcyl🇵🇱 · Leszek Motyka🇵🇱 · Tomasz Stebel🇵🇱
In the high-energy limit of DIS experiments the effective degrees of freedom of QCD are Wilson line operators. Their evolution in the rapidity variable is predicted by the set of Balitsky-JIMWLK evolution equations. We analyze a new class of two-point correlation functions of Wilson line operators where the Wilson lines are taken at different values of the rapidity variable. Such correlation functions can appear in the discussion of the kinematical constraint. We find that in the Langevin formulation of the JIMWLK equation, such correlation functions are affected by an infrared divergence. We discuss a possible regularization of this divergence and its consequences for the implementation of the kinematical constraint for the JIMWLK equation.
hep-phPoS(2025)·2 citations
22*
Physics case for an $e^{+} e^{-}$ collider at 500 GeV and above
Philip Bechtle🇩🇪 · Sven Heinemeyer🇪🇸 · Jenny List🇩🇪 · Gudrid Moortgat-Pick🇩🇪 · Georg Weiglein🇩🇪
Some highlights of the physics case for running an $e^{+} e^{-}$ collider at 500 GeV and above are discussed with a particular emphasis on the experimental access to the Higgs potential via di-Higgs and (at sufficiently high energy) triple Higgs production. The information obtainable from Higgs pair production at about 500 GeV is compared with the prospects for the HL-LHC and with the indirect information that can be obtained from a Higgs factory running at lower energies.
hep-phEPJ Web Conf.(2024)·6 citations
23*
Recasting scalar-tensor theories of gravity for colliders
Andrei Lazanu🇬🇧 · Peter Millington🇬🇧 · Sergio Sevillano Muñoz🇬🇧
Diagrammatic approaches to perturbation theory transformed the practicability of calculations in particle physics. In the case of extended theories of gravity, however, obtaining the relevant diagrammatic rules is non-trivial: we must expand in metric perturbations and around (local) minima of the scalar field potentials, make multiple field redefinitions, and diagonalize kinetic and mass mixings. In this note, we will motivate these theories, introduce the package FeynMG -- a Mathematica extension of FeynRules that automates the process described above -- and highlight an application to a model with unique collider phenomenology.
hep-phgr-qcPoS(2025)·0 citations
24*
Locating the QCD critical point through contours of constant entropy density
Hitansh Shah🇺🇸 · Mauricio Hippert🇧🇷 · Jorge Noronha🇺🇸 · Claudia Ratti🇺🇸 · Volodymyr Vovchenko🇺🇸
We propose a new method to investigate the existence and location of the conjectured high-temperature critical point of strongly interacting matter via contours of constant entropy density. By approximating these lines as a power series in the baryon chemical potential $μ_{B}$ , one can extrapolate them from first-principle results at zero net-baryon density, and use them to locate the QCD critical point, including the associated first-order and spinodal lines. As a proof of principle, we employ currently available continuum-extrapolated first-principle results from the Wuppertal--Budapest collaboration to find a critical point at a temperature and a baryon chemical potential of $T_{c} = 114.3 \pm 6.9$ MeV and $μ_{B, c} = 602.1 \pm 62.1$ MeV, respectively. We advocate for a more precise determination of the required expansion coefficients via lattice QCD simulations as a means of pinpointing the location of the critical endpoint in the phase diagram of strongly interacting matter.
hep-phhep-latnucl-exnucl-thPRC(2026)·55 citations
25*
Hyperparameter Optimisation in Deep Learning from Ensemble Methods: Applications to Proton Structure
Juan Cruz-Martinez🇨🇭 · Aaron Jansen🇳🇱 · Gijs van Oord🇳🇱 · Tanjona R. Rabemananjara🇳🇱 · Carlos M. R. Rocha🇳🇱 · Juan Rojo🇳🇱 · Roy Stegeman🇬🇧
Deep learning models are defined in terms of a large number of hyperparameters, such as network architectures and optimiser settings. These hyperparameters must be determined separately from the model parameters such as network weights, and are often fixed by ad-hoc methods or by manual inspection of the results. An algorithmic, objective determination of hyperparameters demands the introduction of dedicated target metrics, different from those adopted for the model training. Here we present a new approach to the automated determination of hyperparameters in deep learning models based on statistical estimators constructed from an ensemble of models sampling the underlying probability distribution in model space. This strategy requires the simultaneous parallel training of up to several hundreds of models and can be effectively implemented by deploying hardware accelerators such as GPUs. As a proof-of-concept, we apply this method to the determination of the partonic substructure of the proton within the NNPDF framework and demonstrate the robustness of the resultant model uncertainty estimates. The new GPU-optimised NNPDF code results in a speed-up of up to two orders of magnitude, a stabilisation of the memory requirements, and a reduction in energy consumption of up to 90% as compared to sequential CPU-based model training. While focusing on proton structure, our method is fully general and is applicable to any deep learning problem relying on hyperparameter optimisation for an ensemble of models.
hep-phhep-exphysics.comp-phMach.Learn.Sci.Tech.(2025)·9 citations
26*
Multiparticle scalar dark matter with $Z_{N}$ symmetry
Subhaditya Bhattacharya🇮🇳 · Lipika Kolay🇮🇳 · Dipankar Pradhan🇮🇳
More than one dark sector particle transforming under the same symmetry provides one stable dark matter (DM) component which undergoes co-annihilation with the heavier particle(s) decaying to DM. Specific assumptions on the kinematics and on the coupling parameters may render the heavier component(s) stable and contribute as DM. The choices of the charges of the dark sector fields under transformation play a crucial role in the resultant phenomenology. In this paper, we systematically address the possibility of obtaining two scalar DM components under $Z_{N}$ symmetry. We consider both the possibilities of DM being weakly interacting massive particle (WIMP) or pseudofeebly interacting massive particle (pFIMP). We elaborate upon $Z_{3}$ symmetric model, confronting the relic density allowed parameter space with recent most direct and indirect search bounds and prospects. We also highlight the possible distinction of the allowed parameter space in single component and two component cases, as well as between WIMP-WIMP and WIMP-pFIMP scenarios.
hep-phhep-thPRD(2026)·10 citations
27*
SUSY at the FPF
Luis A. Anchordoqui🇺🇸 · Ignatios Antoniadis🇹🇭 · Karim Benakli🇫🇷 · Jules Cunat🇫🇷 · Dieter Lust🇩🇪
Experimental searches for supersymmetry (SUSY) are entering a new era. The failure to observe signals of sparticle production at the Large Hadron Collider (LHC) has eroded the central motivation for SUSY breaking at the weak scale. However, String Theory requires SUSY at the fundamental scale $M_{s}$ and hence SUSY could be broken at some high scale below $M_{s}$ . Actually, if this were the case, the lack of experimental evidence for low-energy SUSY could have been anticipated, because most stringy models with high-scale SUSY breaking predict that sparticles would start popping up above about 10 TeV, well beyond the reach of current LHC experiments. We show that using next generation LHC experiments currently envisioned for the Forward Physics Facility (FPF) we could search for signals of neutrino-modulino oscillations to probe models with string scale in the grand unification region and SUSY breaking driven by sequestered gravity in gauge mediation. This is possible because of the unprecedented flux of neutrinos to be produced as secondary products in LHC collisions during the high-luminosity era and the capability of FPF experiments to detect and identify their flavors.
hep-phEPJC(2025)·5 citations
28*
Beyond The Standard Model electrodynamics in the time domain
Fabrizio Corelli🇮🇹 · Enrico Cannizzaro🇵🇹 · Andrea Caputo🇨🇭 · Paolo Pani🇮🇹
Many motivated extensions of the standard model include new light bosons, such as axions and dark photons, which can mix with the ordinary photon. This latter, when in a dilute plasma, can be dressed by an effective plasma mass. If this is equal to the mass of the new degree of freedom, then a resonance takes place and the probability of transition between states is enhanced. This phenomenon of resonance conversion is at the very basis of multiple probes of dark matter, and it is typically studied within the so-called Landau-Zener approximation for level crossings. This latter is known to break down in a variety of scenarios, such as multiple level crossings or when the de Broglie wave length of the new boson is comparable to the scale over which the background plasma varies. We develop a flexible code adopting a 3+1 formalism in flat spacetime to perform non-linear simulations of systems with photons and new ultralight bosons in the presence of plasma. Our code currently allows to evolve one-dimensional systems, which are the ones of interest for this first study, but can be easily extended to treat three-dimensional spaces, and can be adapted to describe a plethora of realistic astrophysical and cosmological situations. Here we use it to study the breakdown of the Landau-Zener approximation in the case of multiple level crossings and when the slowly-varying plasma approximation ceases to be valid. In this first paper we detail our code and use it to study non-turbulent plasma, where small scale fluctuations can be neglected; their treatment will be considered in an upcoming publication.
hep-phPRD(2025)·1 citation
29*
A Rotating-Wave Comagnetometer Detector for Particle Physics
Itay M. Bloch🇺🇸 · Or Katz🇺🇸
Many extensions of the Standard Model propose the existence of new particles or forces, aiming to answer mysteries such as the identity of the elusive dark matter. Atomic-based detectors are at the forefront of technologies designed to search for these particles or forces through their couplings to fermions, enabling the testing of well-motivated models, such as axion-like particles, which could form dark matter. These detectors also probe new long-range interactions between the detectors and spin-polarized objects, as well as interactions mediated by light particles that break CP symmetry, introducing a coupling between the detector and an unpolarized object. However, the sensitivity of these detectors is often constrained by magnetic noise, limiting their effectiveness to a narrow region of parameter space. We propose and develop a technique, which we name the Rotating Wave comagnetometer (RoW comag), that can suppress magnetic noise at tunable frequencies while maintaining high sensitivity to target signals, significantly expanding the potential reach of these detectors. We analyze its operation for testing various extensions to the Standard Model and show how it could improve current sensitivities by several orders of magnitude. This work paves the way for a new class of tabletop experiments aimed at searching for new physics, including the exploration of well-motivated axion-like particle dark matter models at higher masses than previously attainable.
hep-phhep-exphysics.ins-detquant-ph5 citations
30*
New Angles on Energy Correlators
Samuel Alipour-fard🇺🇸 · Ankita Budhraja🇳🇱 · Jesse Thaler🇺🇸 · Wouter J. Waalewijn🇳🇱
Energy correlators have recently come to the forefront of jet substructure studies at colliders due to their remarkable properties: they naturally separate physics at different scales, are robust to contamination from soft radiation, and offer a direct connection with quantum field theory. The current parametrization used for energy correlators, however, is based on redundant pairwise angles with complex phase space restrictions. In this Letter, we introduce a new parametrization of energy correlators that features a simpler phase space structure and preserves information about the orientation of jet constituents. Further, our parametrization drastically reduces the computational cost to compute energy correlators on experimental data; whereas the time to compute a traditional projected $N$ -point energy correlator scales as $M^{N} / N!$ on a jet with $M$ particles, our new parametrization achieves a scaling of $M^{2} lo g M$ , remarkably independently of N. Even for N=3, this improved scaling is particularly important for studies of heavy ion collisions, and higher values of $N$ will enable new qualitative understanding of gauge theories. Theoretical calculations for our new energy correlators differ from those of traditional parametrizations only at next-to-next-to-leading logarithmic accuracy and beyond, and we expect that our simpler phase space structure will simplify those calculations. We also discuss how to extend our parametrization to resolved $N$ -point energy correlators that encode angular distances between greater numbers of particles, yielding intuitive visualizations of jet substructure that are qualitatively different for different jet samples. We propose two possible generalizations for probing multi-prong jets and testing jet scaling behavior.
hep-phhep-exnucl-exnucl-thPRL(2025)·21 citations
31*
Universality in the Near-Side Energy-Energy Correlator
Xiaohui Liu🇨🇳 · Werner Vogelsang🇩🇪 · Feng Yuan🇺🇸 · Hua Xing Zhu🇨🇳
We investigate the energy-energy correlator (EEC) of hadrons produced on the same side in $e^{+} e^{-}$ annihilation or in leading jets in $pp$ collisions. We observe a remarkable universality of the correlator. Using a non-perturbative transverse momentum dependent (TMD) fragmentation function to model the transition from the ``free-hadron" region to the perturbative collinear region, we are able to describe the near-side shapes and peaks over a wide range of energy for both the $e^{+} e^{-}$ annihilation and the $pp$ jet substructure measurements in terms of just two parameters. We present further predictions for the ratio of the projected three-point energy correlator to the EEC. The excellent agreement between our calculations and the experimental data may provide new insights into the role of non-perturbative physics for EECs, and suggests the possibility of exploring non-perturbative TMDs using theoretical tools developed for the energy correlators.
hep-phhep-exnucl-exnucl-thPRL(2025)·32 citations
32*
Is leptogenesis during gravitational reheating flavourful?
Basabendu Barman🇮🇳 · Arghyajit Datta🇰🇷 · Md Riajul Haque🇮🇳
We examine the impact of charged lepton Yukawa equilibration on leptogenesis during gravitational reheating. During the post-inflationary era, the inflaton field is assumed to oscillate around the minimum of a monomial potential, leading to the gravitational production of Standard Model (SM) particles, constituting the radiation bath. The heavy right-handed neutrinos (RHN), responsible for generating baryon asymmetry via leptogenesis, are also produced through graviton-mediated scattering of the homogeneous inflaton field and thermal bath, as well as from the the inverse decay of the bath particles. By considering both minimal and non-minimal gravitational contributions to SM, we demonstrate that flavour effects can be safely neglected in the minimal reheating scenario. However, with large non-minimal coupling, these effects may become important, depending on the choice of the RHN mass. We identify the corresponding viable parameter space that satisfies the observed baryon asymmetry in each case.
hep-phastro-ph.COJCAP(2025)·5 citations
33*
Dark matter searches at BESIII
Vindhyawasini Prasad🇨🇱
Dark matter (DM) is a new type of invisible matter introduced to explain various features of recent astrophysical observations, including galaxy rotation curves and other fundamental characteristics of our universe. DM may couple to ordinary matter via portals, which open up possibilities for new particles, such as axion-like particle, light Higgs boson, dark photon, and spin-1/2 fermions. If the masses of these particles lie in the MeV to GeV range, they can be explored by high-intensity electron-positron collider experiments, such as the BESIII experiment. BESIII has accumulated a huge amount of datasets at several energy points, including the $J / ψ$ , $ψ (3686)$ , and $ψ (3770)$ resonances. BESIII has recently explored the possibility for axion-like particle and light Higgs boson through radiative $J / ψ$ decays, dark photon via the initial-state radiation process, and a massless dark photon in $Λ_{c}$ decays. This report highlights the latest results from the BESIII experiment on these topics.
↳ hep-exhep-ph2 citations
34*
Searching for new physics in WW and single-W events
Jenny List🇩🇪 · Ulrich Einhaus🇩🇪 · Andre Filipe Silva🇩🇪 · Leonhard Reichenbach🇩🇪
Pair-production and single-production of $W$ bosons provide many opportunities to look for new physics via precision measurements, for instance via scrutinising the involved triple-gauge vertices or by measuring CKM matrix elements in an environment very complementary to $B$ hadron decays. This contribution presents the ongoing work based on full simulation of the ILD concept, exploiting the O( $1 0^{8}$ ) $W$ bosons produced during the $250$ \,GeV stage of the ILC, as well as the CLD concept proposed for the FCC-ee. The projections, which also contribute to two focus topics of the current ECFA study on future Higgs/Top/Electroweak factories, promise improvements of the measurement precision of TGCs and the CKM matrix, respectively, of one to two orders of magnitude with respects to LEP.
↳ hep-exhep-phEPJ Web Conf.(2024)·0 citations
35*
Pair momentum dependence of tilted source in heavy ion collisions
Yevheniia Khyzhniak🇺🇸 · Michael Annan Lisa🇺🇸
In non-central heavy-ion collisions, the particle-emitting source can be tilted away from the beam direction, an effect that becomes particularly significant at collision energies of a few GeV and lower. This phenomenon, manifest itself in many observables such as directed flow, polarization, and vorticity, is therefore important to investigate. In this paper, we study the consistency between the tilt extracted directly from the freeze-out distribution of pions and the tilt parameter obtained using the azimuthally sensitive femtoscopy (asHBT) method. Using the UrQMD model, we demonstrate a strong dependence of the tilt parameter extracted with asHBT on the momentum of the particle pair. Considering the experimental challenges in accessing low particle momenta - where the tilt parameter extracted with asHBT closely matches the tilt of the freeze-out distribution of pions - we propose an exponential extrapolation method to obtain the tilt of the entire freeze-out distribution. This approach aims to enhance the accuracy of experimental measurements of tilt in non-central heavy-ion collisions.
↳ nucl-thhep-phnucl-exPRC(2025)·5 citations
36*
Electron-hole pair production in graphene for two arbitrarily polarized electric fields with a time delay
R. Z. Jiang🇨🇳 · Z. L. Li🇨🇳 · Y. J. Li🇨🇳
The momentum distributions of electron-hole (EH) pair production in graphene for two arbitrarily polarized electric fields with a time delay are investigated employing a massless quantum kinetic equation and compared with the results obtained in electron-positron (EP) pair production from vacuum. For a single elliptically polarized electric field, the momentum distributions of created EH and EP pairs are similar in multiphoton absorption region. However, for two co-directional linearly polarized electric fields with a time delay and no field frequency, the momentum distribution of created EH pairs exhibits ring patterns, which is not present in EP pair production. For two circularly polarized fields with identical or opposite handedness, the momentum distributions of created EH pairs also show Ramsey interference and spiral structures, respectively. Different from EP pair production, the spiral structures are insensitive to the number of oscillation cycles in electric field pulses. For two elliptically polarized fields with same-sign or opposite-sign ellipticity, the momentum distributions of EH pairs are much more insensitive to ellipticity than those in EP pair production. These results provide further theoretical reference for simulating the EP pair production from vacuum in solid-state systems.
↳ cond-mat.mes-hallhep-phEur.Phys.J.Plus(2025)·0 citations
37*
Towards an update of the ILD ZHH analysis
Bryan Bliewert🇩🇪 · Jenny List🇩🇪 · Dimitris Ntounis🇺🇸 · Junping Tian🇯🇵 · Julie Munch Torndal🇩🇪 · Caterina Vernieri🇺🇸
The double Higgs-strahlungs process $e^{+} e^{-} \to Z H H$ allows to access the Higgs self-coupling at center-of-mass energies above $450$ GeV. Its cross-section exhibits a very different behavior as a function of the value of the self-coupling than fusion-type processes like gluon-gluon fusion at LHC (and future hadron colliders) and $W W$ / $Z Z$ fusion at higher energy lepton colliders. Therefore it adds unique information to the picture, in particular should the value of the Higgs self-coupling differ from its Standard Model prediction. The last full evaluation of the potential of the ILC to measure this process is more than ten years old, and since then many of the reconstruction tools have received very significant improvements. This contribution presents the ongoing work in the ILD collaboration to update the ZHH projections for the next European Particle Physics Strategy Update.
↳ hep-exhep-phEPJ Web Conf.(2024)·2 citations
38*
Test of $T$ -invariance in scattering of polarized protons on tensor-polarized deuterons at energies of the NICA SPD
Yu.N. Uzikov🇷🇺 · M.N. Platonova🇷🇺
The effect of violation of $T$ -invariance, provided that $P$ -parity is preserved, is given by the total cross section of the interaction of a vector-polarized particle with a tensor-polarized target. A formalism for calculating this effect developed previously and based on the spin-dependent Glauber theory of elastic $p d$ scattering is used here to calculate the effect under discussion in the range of collision energies corresponding to the invariant mass of the $pN$ system $s_{pN} = 5$ -- $30$ GeV. The spin-dependent amplitudes of elastic $pN$ scattering required for this calculation are taken from existing phenomenological models for $pN$ scattering in the energy region considered.
↳ nucl-thhep-exhep-phnucl-exPhys.Part.Nucl.(2025)·2 citations
39*
The Maximal Gravitational Wave Signal from Asteroid-Mass Primordial Black Hole Mergers At Resonant Microwave Cavities
Stefano Profumo🇺🇸 · Lucas Brown🇺🇸 · Christopher Ewasiuk🇺🇸 · Sean Ricarte🇺🇸 · Henry Su🇺🇸
Primordial black holes can be the entirety of the dark matter in a broad, approximately five-orders-of-magnitude-wide mass range, the ``asteroid mass range'', between $1 0^{- 16} M_{Sun}$ -- where constraints originate from evaporation -- and $1 0^{- 11} M_{Sun}$ -- from microlensing. A direct detection in this mass range is very challenging with any known observational or experimental methods. Here we update the calculation of the sight distance for narrow-band detectors such as resonant microwave cavities, and the resulting maximal event rate. We find that the largest detection rates are associated with binaries from non-monochromatic mass functions in early-formed three-body systems. Even in the most optimistic setup, these events are anticipated to be extremely rare.
↳ astro-ph.HEastro-ph.COgr-qchep-ph+1PRD(2025)·3 citations
40*
Quark mass effects in octet baryon magnetic polarisabilities via lattice QCD
Thomas Kabelitz🇦🇺 · Waseem Kamleh🇦🇺 · Derek Leinweber🇦🇺
The quark mass dependence of octet baryon magnetic polarisabilities is examined at the level of individual quark-sector contributions in the uniform background-field approach of lattice QCD. The aim is to understand the direct impact of increasing the mass of a quark flavour on the magnetic polarisability and indirect or environmental effects associated with changing the mass of spectator quarks, insensitive to the background magnetic field. Noting the need to set the electric charge of some quark flavours to zero, a fractionally charged baryon formalism is introduced. We find that increasing the mass of the charged quark flavour directly causes its contribution to the magnetic polarisability to decrease. However, increasing the mass of the spectator quark flavour indirectly acts to increase the magnetic polarisability. To gain a deeper understanding of these effects, we evaluate the predictions of the constituent quark model in this context. While the model provides a compelling explanation for the environmental effect of varying the spectator quark mass, an explanation of the direct mass dependence is more complicated as competing factors combine in the final result. The lattice results indicate the key factor is a reduction in the constituent quark magnetic moment with increasing quark mass, as it governs the strength of the magnetic transition to the nearby decuplet baryon.
↳ hep-lathep-phnucl-thPRD(2025)·1 citation
41*
Heavy Quarkonium-nuclear bound states within a generalized linear sigma model
Arpita Mondal🇮🇳 · Amruta Mishra🇮🇳
We estimate the binding energies of charmonium ( $J / ψ$ , $ψ (2 S)$ , $ψ (1 D)$ , $χ_{c 0}$ , $χ_{c 1}$ , $χ_{c 2}$ ) and bottomonium ( $Υ (1 S)$ , $Υ (2 S)$ , $Υ_{2} (1 D)$ , $χ_{b 0}$ , $χ_{b 1}$ , $χ_{b 2}$ ) states bound in various nuclei ( $^{4} He$ , $^{12} C$ , $^{16} O$ , $^{40} Ca$ , $^{90} Zr$ , and $^{208} Pb$ ) using the quarkonia-nuclei potentials obtained from their mass shifts in nuclear matter within the generalized linear sigma model. In the absence of light partons in heavy quarkonia, at the tree level, the medium modifications are driven by the gluon condensate, which is simulated within this model through a scalar dilaton field, $χ$ , by introducing broken scale invariance of QCD. Our study shows that charmonium states bind more deeply with the atomic nuclei as compared to bottomonium states, providing a better probe for nuclear medium effects. Such bound states' investigations are particularly interesting for the upcoming J-PARC-E29, $P ˉ ANDA$ @FAIR, and CEBAF@JLab experiments. The mass shifts of the heavy quarkonium states in hot isospin asymmetric nuclear matter are investigated and are observed to receive an appreciable medium modification. These medium effects are anticipated at FAIR@GSI, where such neutron-rich hot nuclear matter is expected to be produced.
↳ nucl-thhep-ph1 citation
42*
Energy-Momentum tensor correlators in $ϕ^{4}$ theory I: The spin-zero sector
Nikos Irges🇬🇷 · Leonidas Karageorgos🇬🇷
We revisit the construction of the renormalized trace $Θ$ of the Energy-Momentum tensor in the four-dimensional $λ ϕ^{4}$ theory,using dimensional regularization in $d = 4 - \ve$ dimensions. We first construct several basic correlators such as $⟨ ϕ^{2} ϕϕ ⟩$ , $⟨ ϕ^{4} ϕϕ ⟩$ to order $λ^{2}$ and from these the correlators $⟨ K_{I} ϕϕ ⟩$ and $⟨ K_{I} K_{J} ⟩$ with $K_{I}$ the basis of dimension $d$ operators. We then match the limit of their expressions on the Wilson-Fisher fixed point to the corresponding expressions obtained in Conformal Field Theory. Then, using the 3-point function $⟨ Θ ϕϕ ⟩$ , we construct the operator $Θ$ as a certain linear combination of the basis operators, using the requirements that $Θ$ should vanish on the fixed point and that it should have zero anomalous dimension. Finally, we compute the 2-point function $⟨ ΘΘ ⟩$ and we show that it obeys an eigenvalue equation that gives additional information about the internal structure of the Energy-Momentum tensor operator to what is already contained in its Callan-Symanzik equation.
↳ hep-thhep-phNPB(2025)·3 citations
43*
Searching for Axion-Like Particles with X-ray Observations of Alpha Centauri
Yu-Xuan Chen🇨🇳 · Lei Lei🇨🇳 · Zi-Qing Xia🇨🇳 · Ziwei Wang🇨🇳 · Yue-Lin Sming Tsai🇨🇳 · Yi-Zhong Fan🇨🇳
We investigate the production of axion-like particles (ALPs) in stellar cores, where they interact with electromagnetic fields and electrons, with typical masses between $O (0.1)$ and $O (10)$ keV. These low-energy ALPs are gravitationally trapped in the orbits of stars and subsequently decay into two photons that we detect as monochromatic X-ray lines. We propose to search for these gravitationally trapped ALPs in the Alpha Centauri binary system, our closest stellar neighbor, using sensitive X-ray detectors like Chandra and eROSITA. Our search for ALP decay signals in the energy range of $0.2$ keV to $10$ keV yielded null results, thus establishing the most stringent limits on ALP interactions to date. In the case of ALP-electron coupling $g_{a ee} \leq 1 0^{- 15}$ , we have improved the limits on the ALP-photon coupling $g_{aγ γ}$ in ALP mass range between $0.25 \keV$ and $5 \keV$ , compared to previous measurements, including those from GW170817, SN 2023ixf, and other sources, and specially the improvement reaches about 2 orders of magnitude at the mass of 2 keV. Even tighter constraints are set for larger $g_{a ee}$ .
↳ astro-ph.HEhep-phPRL(2025)·8 citations
44*
On priors and scale cuts in EFT-based full-shape analyses
Anton Chudaykin🇨🇭 · Mikhail M. Ivanov🇺🇸 · Takahiro Nishimichi🇯🇵
Parameter estimation from galaxy survey data from the full-shape method depends on scale cuts and priors on EFT parameters. The effects of priors, including the so-called ''prior volume'' phenomenon have been originally studied in Ivanov et al. (2019) and subsequent works. In this note, we repeat and extend these tests and also apply them to other priors used in the literature. We point out that in addition to the ''prior volume'' effect there is a more dangerous effect that is largely overlooked: a systematic bias on cosmological parameters due to overoptimistic scale cuts. Unlike the ''prior volume'' effect, this is a genuine systematic bias due to two-loop corrections that does not vanish with better priors or with larger data volumes. Our study is based on the high fidelity BOSS-like PT Challenge simulation data which offer many advantages over analyses based on synthetic data generated with fitting pipelines. We show that some analysis choices associated with the PyBird code, especially the scale cuts, significantly bias parameter recovery, overestimating $σ_{8}$ by over $5%$ (equivalent to $1 σ$ ). The bias on measured EFT parameters is even more significant. In contrast, the analysis choices associated with the CLASS-PT code lead to much smaller ( $≲ 1%$ ) shifts in cosmological parameters based on their best-fit values.
↳ astro-ph.COhep-phPRD(2026)·24 citations
45*
511 keV Galactic Photons from a Dark Matter Spike
Pedro De la Torre Luque🇪🇸 · Shyam Balaji🇬🇧 · Malcolm Fairbairn🇬🇧 · Filippo Sala🇮🇹 · Joseph Silk🇫🇷
We propose that a dark matter (DM) spike around the Galactic Center's (GC) supermassive black hole, Sgr A*, could account for most of the bulge's measured 511 keV line intensity while remaining cosmologically compatible. DM annihilation can be the primary source of the 511 keV line emission without violating constraints from disk emission observations and in-flight positron annihilation with the interstellar medium, provided the disk emission is dominated by an astrophysical source of low-energy positrons. We find that a DM mass up to approximately 20 MeV, either with a Gondolo-Silk spike or one softened by stellar heating, could explain the observed 511 keV bulge emission profile. Our proposal can be tested by future observations of the continuum diffuse emission close to the GC.
↳ astro-ph.HEhep-phJCAP(2025)·24 citations
46*
Towards a Complete Treatment of Scalar-induced Gravitational Waves with Early Matter Domination
Soubhik Kumar🇺🇸 · Hanwen Tai🇺🇸 · Lian-Tao Wang🇺🇸
Large curvature perturbations can source an observable amount of stochastic gravitational wave background (SGWB). We consider several scenarios where small-scale curvature perturbations are naturally enhanced due to the presence of additional spectator fields during inflation. The same spectator fields can lead to a period of early matter domination (EMD) after inflation. We compute the inflationary spectrum of curvature perturbation and determine its evolution at later times, taking into account both the onset and the end of the EMD epoch, and also the impact of relative velocity perturbation between matter and radiation. The feature that the same field is responsible for both enhanced perturbations and the EMD era, leads to a predictive framework within which the full frequency dependence of SGWB can be computed. The SGWB can be observed in several detectors, including those focused on the nano-Hz regime. Our numerical framework can also be used to study other non-standard cosmological histories.
↳ gr-qcastro-ph.COhep-phJCAP(2025)·19 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.