HEP Phenomenology·hep-ph

Wed·Sep 30, 2026Wednesday·September 30, 2026

11 papers—6 primary·5 cross-listed

01
Constraining dark matter using 20-year INTEGRAL/IBIS observations II: Sub-GeV dark matter
Jordan Koechler · Pedro De la Torre Luque
We present new constraints on sub-GeV dark matter (DM) annihilation and decay using twenty years of diffuse hard X-ray observations from the INTEGRAL/IBIS telescope. By performing a joint analysis of the spectral and morphological information contained in the IBIS dataset, we simultaneously fit Galactic longitudinal profiles and energy spectra, exploiting their complementary signatures to disentangle potential DM signals from the dominant astrophysical backgrounds. We use physically motivated background models combining inverse-Compton (IC) emission from Galactic cosmic-ray electrons with thermal emission from unresolved accreting white dwarfs, and consistently include the secondary IC emission generated by DM-induced electron and positron populations propagated through the Galaxy. We conservatively derive 95% upper limits on the annihilation cross section $⟨ σ v ⟩$ and decay half-life $τ$ for the $e^{+} e^{-}$ , $μ^{+} μ^{-}$ , and $π^{+} π^{-}$ final states across the mass range 1 MeV to 5 GeV. Our constraints are in the range $1 0^{- 28}$ cm $^{3}$ /s $≲ ⟨ σ v ⟩ ≲ 1 0^{- 26}$ cm $^{3}$ /s for annihilation and $τ ≳ 1 0^{25}$ s for decay at DM masses of a few MeV, improving upon existing X-ray limits by up to two orders of magnitude over much of the mass range. Our bounds are translated into constraints on the kinetic mixing parameter $ϵ$ of a dark photon and the scalar-Higgs mixing angle $sin θ$ , and compared with existing indirect, direct and accelerator limits available, providing a comprehensive picture of the allowed parameter space for light portal DM.
hep-phastro-ph.COastro-ph.HE
02
Resummation of Next-to-Leading Non-Global Logarithms in Higgs Production
Thomas Becher · Rebecca von Kuk · Xinyu Qin · Nicolas Schalch
We analyze Higgs production at the LHC with a jet veto at central rapidities and present the first next-to-leading logarithmic resummation of non-global logarithms for this process. The resummation combines one-loop hard and soft matching functions with two-loop anomalous dimensions in the large- $N_{c}$ limit. To perform the resummation we numerically solve renormalization group equations via the parton-shower framework MARZILI. After matching to fixed order, we perform a detailed study of different sources of uncertainties. We find that the hard matching corrections dominate by far and are substantially larger than in Drell-Yan production. Together with earlier results for Drell-Yan, these are the first resummations of subleading non-global logarithms in hadron-collider cross sections, and they provide a benchmark for logarithmically accurate parton showers.
hep-ph
03
Higgs pseudo-observables in $e^{+} e^{-} \to hγ$
Fausto Boniotti · Gino Isidori · Christiane Mayer · Emanuelle Pinsard
We analyse the process $e^{+} e^{-} \to hγ$ in the Standard Model (SM) and in generic extensions with heavy new physics, using the framework of Higgs pseudo-observables. We decompose the one-loop amplitude into separately gauge-invariant photon-pole, $Z$ -pole, and non-pole contributions. For heavy new physics, we show that the leading deviations from the SM are necessarily encoded in the $hγ γ$ and $h Z γ$ on-shell effective couplings. Genuine $e^{+} e^{-} hγ$ contact interactions arise only at higher orders in a derivative expansion, both in SMEFT and HEFT. Although Higgs decays constrain the magnitudes of these pseudo-observables, they leave their relative sign undetermined. Measurements of $e^{+} e^{-} \to hγ$ at different FCC-ee energies can resolve this ambiguity. Deviations incompatible with this description would instead point towards relatively light new degrees of freedom, as illustrated by a simplified $Z^{'}$ model.
hep-ph
04
Infrared Subtraction with Artificial Intelligence
Wenjie He · Xiaohui Liu · Yandong Liu · Zhan Wang
We present AI-developed local infrared subtraction, building on projection to Born and EFT matching. The framework separates an integrable radiation term from a finite contribution at Born kinematics, referred to as the Born contact. The contact is determined using the EFT singular distribution in a resolution observable such as N-jettiness $τ_{N}$ . Under human physics guidance, an LLM develops two implementations. One uses a neural network for phase space projection and fits the contact by matching to EFT cumulants. The other uses an analytic construction that keeps the Born momenta fixed while integrating over radiation. It combines the EFT $δ (τ_{N})$ coefficient with finite 4-dimensional radiation integrals to calculate the contact term directly. This gives a local subtraction formula without a slicing parameter, while reusing existing lower-order radiation calculations and EFT singular predictions. As a demonstration, we reconstruct the full NLO correction for massless 3- and 4-jet production in electron-positron annihilation. The attempt to the NNLO dijet production is also made by recursively using the NLO P2B construction with the LLM designing machine-learning controls to reduce the variance of the contact integral. The tested predictions are in good agreement with EERAD3. The numerical calculation and projection-network training use a 2020 Apple M1 MacBook, without GPU acceleration, illustrating the feasibility of the construction with modest computing resources. The appendices develop an extension of the local subtraction to 3-jet NNLO, giving explicit radiation maps and a proposed contact formula. We also show how to integrate over NNLO radiation while keeping the Born momenta fixed, for any number of massless final-state jets. Our results demonstrate how AI can help higher-order calculations by constructing infrared subtraction and improving its numerical integration.
hep-phcs.AIhep-exnucl-ex+1
05
Electric Dipole Moments as Precision Probes of CP-Violating Top-Quark Interactions in SMEFT
Subhajit Kala · Soumitra Nandi · Sonakshi Saha
Electric dipole moments (EDMs) provide some of the most sensitive probes of CP-violating interactions beyond the Standard Model (SM). Within the Standard Model Effective Field Theory (SMEFT), we investigate constraints on CP-violating top-quark interactions using current and projected leptonic and hadronic EDM measurements. Our analysis incorporates the complete chain of relevant effects, including one- and two-loop matching, Barr-Zee contributions, Weinberg operator and heavy-quark threshold corrections, and renormalization-group induced operator mixing. We demonstrate the strong complementarity between leptonic and hadronic EDM observables and show that future proton EDM searches could significantly strengthen constraints on several CP-violating top-quark interactions.
hep-phhep-ex
06
High-energy logarithms and precision at the LHC
Jeppe R. Andersen · Sebastian Jaskiewicz · Andreas Maier · Jennifer M. Smillie
We address the breakdown of fixed-order perturbation theory due to logarithms in $s / p_{t}^{2}$ for processes involving two jets or more at the energies currently explored at the LHC. The problem manifests itself in various ways: an obvious breakdown of the perturbative series for some kinematic distributions, highly asymmetric scale variations in other distributions, and the need for an artificially large renormalisation scale to even achieve numerical stability. As we demonstrate, the problem is solved through the resummation of these high-energy logarithms. The customary choice of a large renormalisation scale of $m_{j_{1} j_{2}}$ offers no systematic resolution. This breakdown in fixed order predictions is illustrated for the production of $Z$ +dijets. We show that resummed predictions obtained using \HighEJ matched to fixed order obtain accurate predictions for all the relevant distributions investigated in a recent ATLAS measurement.
hep-phhep-ex
07
Low Frequency Gravitational Wave Detection with Gravito-Magnetism
Reza Ebadi · Surjeet Rajendran
The detection of gravitational waves in the low-frequency band (10 nHz to 1 micro-Hz) using inner solar system proof masses is severely limited by Newtonian gravity gradient noise (GGN) sourced by the asteroid belt. In this paper, we propose a novel detection concept that exploits the relativistic nature of gravitational waves to break the degeneracy between the signal and the asteroid GGN background. The non-relativistic motion of asteroids dominantly sources gravito-electric fields, with velocity suppressed gravito-magnetic components. Relativistic gravitational waves produce gravito-electric and gravito-magnetic components of equal magnitude. We propose detecting the gravito-magnetic component of low frequency gravitational waves using the Lorentz acceleration of test bodies. The measurement of this Lorentz acceleration is metrologically possible due to the fact that expected astrophysical sources of low frequency gravitational waves have considerably higher characteristic strains than the strains typically expected at higher frequencies. We show that this measurement allows for unambiguous extraction of the gravitational wave signal from the gravity gradient noise in a three satellite constellation. The gravito-magnetic measurement still requires a proof mass that is well isolated from non-gravitational noise. We propose the use of atom interferometers to serve as such a pristine inertial reference.
↳ gr-qcastro-ph.COastro-ph.IMhep-ph+2
08
Current and Future Constraints on the Primordial Power Spectrum
Zachary Cheslog · Emily Finson · Amanda MacInnis · Neelima Sehgal · Niayesh Afshordi · Simran K. Nerval · Renée Hložek
The primordial scalar power spectrum provides a powerful window onto early-universe physics, including a broad class of inflationary scenarios. These models often predict a characteristic scalar spectral index $(n_{s})$ , nonzero running $(α_{s})$ , or more general deviations from a pure power-law form. We find that freeing the number of light relic species $(N_{eff})$ and the sum of the neutrino masses $(\sum m_{ν})$ broadens the $n_{s}$ error contours enough that key early-Universe models are no longer excluded. In particular, while both Starobinsky inflation and the Bi-thermal Big Bang model are ruled out at about the 95% confidence level in the six-parameter $Λ$ CDM model, we find that in the nine-parameter $Λ CDM + α_{s} + N_{eff} + \sum m_{ν}$ model, CMB data from Planck, ACT, and SPT (CMB-PAS) combined with DESI DR2 give $n_{s} = 0.9758 \pm 0.0064$ and $α_{s} = 0.0080 \pm 0.0064$ , consistent with both models. Future CMB facilities will sharply improve constraints on $n_{s}$ , $α_{s}$ , and, more generally, the binned primordial power spectrum $P (k)$ . For example, CMB-PAS constrains $e^{- 2 τ} P (k = 0.2 Mpc^{- 1})$ to 0.5%, while SO-like and CMB-HD-like surveys would tighten this to 0.1%; CMB-HD would also extend this measurement to smaller, previously unprobed scales, constraining $e^{- 2 τ} P (k = 30 Mpc^{- 1})$ to within a factor of ten. We release our forecast code and update the public CMB-HD likelihood and Fisher codes to support CLASS in addition to CAMB.
↳ astro-ph.COhep-phhep-th
09
Helicity-Resolved Constructibility from Unified Ward Identities
Jaehoon Jeong
We show that the large- $z$ behavior of massive higher-spin particles under all-line transverse shifts is controlled by the helicity magnitude rather than the total spin. The apparent additional $z$ growth of nonextremal higher-spin wavefunctions is removed by unified Ward identities acting independently on each vector index. To expose this structure, we embed a four-dimensional massive momentum and its mass into an auxiliary null five-vector, whose fifth-current components characterize the breaking and restoration of the massless Ward identities. These identities determine the fixed-helicity large- $z$ scaling and yield a helicity-resolved constructibility criterion valid for arbitrary spin. Provided the stripped kinematic tensor remains finite in the massless limit, increasing the total spin does not by itself worsen constructibility, and amplitudes with nonnegative coupling dimension are constructible for all helicity configurations at five points and beyond.
↳ hep-thhep-ph
10
Enhanced density fluctuations: consequences for stellar dynamics and dark matter substructure
Wenzer Qin · David E. Kaplan · Neal Weiner
Enhanced density fluctuations form early dark matter halos, which serve as early gravitational potential wells for baryons. These baryons can then condense to form stars and black holes at high redshifts, $1 + z ≳ 100$ . Larger density fluctuations result in denser halos with higher virial temperatures; hence, a halo at a mass that is below the threshold for forming stars under standard astrophysical expectations may form astrophysical objects if its initial density is higher than expected, although the exact threshold for compact object formation is subject to large astrophysical uncertainties. We outline the conditions under which enhanced density fluctuations form dark (star-less) halos, early galaxies, or even star clusters. Using toy model enhancements to the primordial power spectrum that have been shown to explain the abundances of ``little red dots", along with our fiducial set of astrophysical parameters, we show that the number of clusters initially captured by the Milky Way is highly sensitive to the shape of the enhancement, with the narrowly peaked enhancement resulting in $50$ clusters and the step-function enhancement resulting in $\sim 4.1 \times 1 0^{5}$ . The initial stellar masses of the clusters is also $O (100) M_{⊙}$ , although this range is also dependent on the shape of the enhancement. In addition, the abundance of dark matter subhalos with masses greater than $1 0^{7} M_{⊙}$ can be enhanced by as much as a factor of $\sim 6.5$ and is denser than in $Λ$ CDM, which will increase their detectability in future stellar stream surveys such as the Via Project.
↳ astro-ph.COastro-ph.GAhep-ph
11
A parameter independent analysis of the QCD chiral phase transition and its universal critical behaviour
Jishnu Goswami · Frithjof Karsch · Sabarnya Mitra · Christian Schmidt
We make use of unique properties of scaling functions to estimate the chiral phase transition temperature and corresponding universal critical parameters of this phase transition directly from (2+1)-flavor QCD simulations with highly improved staggered fermions on lattices with temporal extent $N_{τ} = 8$ . Working with an improved chiral order parameter for quantifying chiral symmetry breaking, we analyze the finite-volume dependence of this observable for a wide range of lattice volumes and light quark masses, and quantitatively estimate the deviations from the expected universal scaling behaviour as a function of the light-to-strange quark mass ratio.
↳ hep-lathep-phhep-thnucl-ex+1