arXane › Physics
Wednesday, 4 November 2026: 33 new papers, 11 cross-lists and 38 replacements in High Energy Physics - Phenomenology (hep-ph), in arXiv's order, with full abstracts. The same papers as arXiv's own listing, set as a newspaper; every title links to arXiv.
SecRed is a C++ program for the reduction of multi-loop Feynman integrals with integration-by-parts (IBP) identities. It reduces an integral family sector by sector for memory control and parallelism, and adds algorithms designed for that setting: an adaptive seed box with a corner cut, an optional seed truncation, a subsector level filter, and symmetry relations expanded only from the master integrals of a sector. A global stage assembles the retained equations and performs the finite-field reconstruction of the coefficients using FiniteFlow or FireFly, repeating the elimination over a sequence of primes. On the elimination side, a coefficient-free plan records the elimination order once and is replayed at each prime, so that only the arithmetic is repeated, and a head score orders the equations to reduce fill-in during the elimination. The program is demonstrated on a two-loop five-point non-planar family and on a four-loop cut family, where assembling the global equation system as a whole would exceed the memory of a single node.
We present a native transverse-momentum realization of the Collins/CSS2 leading-power transverse-momentum-dependent (TMD) factorization framework. The construction connects fixed-order distributional matching, origin contacts, unexpanded two-scale evolution, and a differentiable interface for hadronic structure. An endpoint-independent canonical scale with a specified infrared completion generates a Collins--Soper kernel on a common invariant domain. Complete canonical legs are bounded and admit constructive momentum-space evaluation through resolvent convolutions or elliptic solves. We give contact and finite-bin error bounds, parent-to-momentum-boundary translations, ordered flavor recurrences, and an all-order argument for the four exponent towers of $N^3\mathrm{LL}$ evolution. Localized joint-$(x,k_T)$ inputs, nonperturbative rapidity broadening, regulated moments and the full-spectrum subtraction are formulated as distinct parts of the prescription. The physical realization uses sourced four-loop beta/cusp and three-loop noncusp/Collins--Soper ingredients with strict-NLO hard/OPE boundaries. Non-Gaussian continuum tests and three-scale physical-PDF comparisons validate ordinary legs, contacts, individual insertions and analytic input derivatives. Including a declared bound on the continuation above a finite PDF table, physical bin discrepancies remain below $4.27\times10^{-5}$ of the peak reference bin. A qualified proton--proton Drell--Yan and neural-closure demonstration connects the method to inverse use. Higher-order boundary assembly and matched observables are specified without claiming an implemented $N^3\mathrm{LL}'$ spectrum or a completed global extraction.
We investigate the topological signatures of neutral-current Non-Standard Interactions (NSI) in long-baseline neutrino oscillations by extending the open-path Pancharatnam geometric phase framework. Incorporating off-diagonal vector couplings ($\varepsilon_{e\tau} = |\varepsilon_{e\tau}|e^{i\phi_{e\tau}}$) into the discrete-layer matter Hamiltonian across the DUNE baseline ($L = 1300\text{ km}$), we analyze the state evolution for both neutrino ($\nu_\mu \to \nu_e$) and antineutrino ($\bar{\nu}_\mu \to \bar{\nu}_e$) appearance channels over the broadband energy spectrum $E_\nu \in [0.5, 8.0]\text{ GeV}$. Our analysis demonstrates that complex NSI phases imprint distinct, energy-dependent spectral dispersions onto the open-path geometric holonomies $\Phi_g^{(n)}$ and their $\mathcal{CP}$-conjugate counterparts. By clarifying that these geometric phases manifest through gauge-invariant interference terms $\Delta\Gamma_{nm}$ rather than asymptotic single-channel measurements, we construct the $\mathcal{CP}$-violating geometric phase differences $\Delta\Phi_g^{\mathrm{CP}}$. We show that the interplay between these geometric dispersions and the matter-potential sign reversal under $\mathcal{CP}$-conjugation forces the neutrino and antineutrino degeneracy bands to intersect at non-parallel angles in the two-dimensional $(\delta_{\mathrm{CP}}, \phi_{e\tau})$ parameter space. This non-trivial topological intersection isolates a unique physical solution, providing a robust, independent diagnostic capable of breaking persistent parameter degeneracies even under realistic calorimetric energy smearing.
We present the first next-to-next-to-leading-order (NNLO) predictions for inclusive color-singlet toponium hadroproduction within NRQCD in the zero-width limit for the top quark. The central new result is the NNLO QCD correction to the short-distance coefficient for pseudoscalar toponium production. The predictions include electroweak and relativistic corrections, additional production channels, and perturbatively evaluated bound-state matrix elements. At the Large Hadron Collider proton-proton center-of-mass energy of $13\,\mathrm{TeV}$, we obtain a cross section of $4.87^{+0.63}_{-0.65}\,\mathrm{pb}$, with scale and parametric uncertainties combined. The NNLO corrections reduce the renormalization- and factorization-scale uncertainties by approximately a factor of four relative to NLO, to the few-percent level. The dominant remaining uncertainty arises from the Coulomb-scale dependence of the bound-state matrix elements.
In traditional approach to the doublet-triplet splitting problem in grand unified theories (GUTs) it is assumed that color-triplet partner of the Higgs doublet must be superheavy in order not to mediate proton decay. However, it has been proposed [1] that the splitting, instead of the mass sector, can occur among the Yukawa couplings. In this scenario the color-triplet emerges as a long-lived $T$-particle with the mass around the TeV scale. This framework provides a direct low-energy window into GUT physics. In the present paper, we study an explicit supersymmetric $SO(10)$ GUT which realizes this mechanism, including effects of gravity-mediated supersymmetry breaking. We show how the shift of the heavy fields, triggered by supersymmetry-breaking, generates a tiny coupling between the $T$-particle and the Standard Model fields and explore the resulting phenomenology. Depending on the order of gravitino mass in which the coupling emerges, the lifetime of the $T$-particle is either around a second or exceeds the age of the Universe. In our analysis, we validate some earlier constraints on (super)gravity vacua imposed by the $S$-matrix: based on the Goldstino Argument, we show that none of the GUT vacua have positive energy densities, whereas the Minkowski vacua are safe against tunneling. We also highlight the role of the species scale cutoff in sensitivity of the low energy observables towards the GUT physics.
Cosmic-ray antideuterons and antihelium-3 nuclei are promising probes of dark matter (DM). In light of potential detections of heavy antinuclei at AMS-02, we investigate a recently proposed scenario in which DM annihilates into color-singlet scalars carrying baryon and lepton number, which has been shown to enhance antideuteron and antihelium-3 fluxes relative to antiprotons. Accounting for Galactic propagation and detector sensitivities, we calculate the number of events predicted by our model for parameters that are compatible with the seven-year AMS-02 antiproton data. Broad regions of the DM-mediator mass plane result in observable antideuteron fluxes at AMS-02 and GAPS. While detecting antihelium-3 remains more challenging, potentially detectable fluxes can arise for light mediators and moderately light DM, and in general are enhanced relative to the standard WIMP predictions. Furthermore, we find antihelium-to-antideuteron event ratios of O(0.1), closer to those suggested by the reported AMS-02 candidate events than conventional WIMP predictions.
We argue that the squark simplified model commonly used in collider analyses fails to represent realistic low-energy supersymmetric models and significantly underestimates squark production rates at hadron colliders. This has important implications for extracting squark mass limits at the LHC and assessing the potential reach of HL-LHC or the FCC-hh. In particular, we find that the current LHC squark mass limit is realistically in the range of 2.6-3.0 TeV, rather than the 1.7-1.8 TeV range that is typically quoted based on the simplified model.
The years preceding a supernova (SN) can constrain new electrophilic bosons with MeV masses more than the explosion itself. Although cooler than SNe, the massive progenitors maintain consistently high temperatures much longer, injecting more particles whose decays to positrons contribute to the diffuse Galactic 511-keV emission. For dark photons, the increase is exacerbated by the lower plasma frequency compared to SNe, where MeV excitations are screened. We find preSNe bounds on dark photon couplings up to two orders of magnitude stronger than SNe for masses between 1 and 3~MeV, with similar improvements for other electrophilic species such as axion-like particles.
Feebly interacting particles (FIPs) arise generically in dark-sector extensions of the Standard Model (SM). Among the simplest and most theoretically motivated such candidates is a dark scalar that mixes with the SM Higgs boson, acting as a mediator between the dark sector and the SM. For sufficiently small mixing, such a dark scalar manifests at collider experiments as a long-lived particle with a macroscopic decay length---a signature to which conventional general-purpose detectors have limited sensitivity. The MoEDAL-MAPP experiment is a dedicated search facility at the Large Hadron Collider (LHC) targeting long-lived FIPs as avatars of physics beyond the SM. We present $95\%$ confidence-level background-free sensitivity projections for the MAPP-1 and MAPP-2 detectors at the High-Luminosity LHC to Higgs-portal dark scalars produced via rare $B$-meson decays and exotic Higgs boson decays. Our results establish the proposed MAPP-2 detector as a complementary probe of feebly-coupled dark scalars, with sensitivity to lifetimes beyond the reach of existing collider searches.
We re-assess effects of Axion Electrodynamics in the presence of non-homogeneous background magnetic fields. The Primakoff effect, which is an ALP-photon mixing induced by a background magnetic field, is generalized to the case of non-homogeneous backgrounds. The production of ALPs from a magnetized plasma thermal medium is also computed. The Eddington's solar standard model is adopted as the phenomenological scenario for our settings, and new bounds on the Axion Electrodynamics parameter space are imposed by considering helioseismological and neutrino observational measurements.
We update an $SU(3)_F$ analysis of $D\to PP$ decays ($P\equiv \pi, K$) in which the dominant $SU(3)_F$-breaking effects are modeled through final-state interactions. The new fit improves the description relative to the previous parameter set, although significant global tension remains, mainly in charged-$D$ modes. Within the adopted rescattering model, the direct CP asymmetries in $D^0\to\pi^+\pi^-$, $K^+K^-$, $\pi^0\pi^0$, and $K_S^0 K_S^0$ depend on two additional reduced amplitudes. Using the $D^0\to\pi^+\pi^-$ and $D^0\to K^+K^-$ asymmetries as inputs, we derive conditional predictions for the two neutral modes. The OZI-motivated benchmark $\Delta_4=0$ is mildly disfavored by the charged-mode asymmetries and leads to substantially smaller asymmetries in the neutral modes, which can be tested with more precise $K_S^0K_S^0$ and $\pi^0\pi^0$ measurements.
We present a model for calculating the forward elastic analyzing power $A_\text{N}^{pA}(t)$ in proton-nucleus scattering, based on the Glauber approximation and incorporating soft-photon exchange corrections. The model is tested against 100 GeV HJET measurements for several nuclei, including Au, Ru, Zr, Al, O, C, and the deuteron. The calculations use Woods-Saxon parameters to describe the nuclear density distributions, as well as the proton-proton and proton-neutron hadronic spin-flip amplitudes, with the latter constrained by a Regge fit to HJET $pp$ data. Using the nominal input parameters, the calculations provide a reasonable description of the measured analyzing powers, although further refinement is needed to achieve a satisfactory fit. Allowing the input parameters to vary in the fits substantially improves the agreement with the data, yielding effective parametrizations of $A_\text{N}^{pA}(t)$ in terms of three or four parameters, depending on the nucleus. Notably, the nominal values of the imaginary part of the effective proton-nucleus spin-flip parameter $r_5^{pA}$ agree well with the fitted values for all nuclei considered. Subject to the limitations of the present model, this observation concerning $\operatorname{Im} r_5^{pA}$ is consistent with the proton-proton spin-flip amplitudes measured at HJET and supports the interpretation of a non-zero Pomeron spin-flip coupling. The results presented in this paper also motivate further investigation of the energy dependence of the proton-nucleon spin-flip amplitude using HJET measurements over a broad range of beam energies, with potential applications to proton-carbon and \(^3\)He polarimetry at the Electron-Ion Collider.
Holographic predictions for vector-meson spin alignment are difficult to compare between charmonium and light vector mesons, as the two sectors are typically treated in different rotating backgrounds and spectral prescriptions. Consequently, it remains unclear whether a single rotating medium can generate the opposite polarization preferences observed in data. We address this by placing \(J/\psi\) and \(\phi\) in one soft-wall model on the planar limit of a five-dimensional equal-spin Myers--Perry (MP) AdS black hole, computing spectral functions and spin alignment within the same current-correlator framework; the nonrotating results of Sheng et al. [Phys. Rev. D 110, 056047 (2024)] are recovered at \(a=0\). At \(T=0.15~\mathrm{GeV}\), \(J/\psi\) retains a clear resonance peak, whereas \(\phi\) shows no narrow peak and instead behaves as a broad distribution consistent with unstable \(s\bar{s}\) pairs. For \(J/\psi\) along \(z\), rotation enhances the positive deviation of \(\rho_{00}^{h}\) from \(1/3\) at low and intermediate momenta but suppresses it at high momenta; along \(x\), the effect is small. For \(\phi\), rotation enhances the negative deviation, more along \(z\) than along \(x\). The opposite helicity-frame signs and the opposing azimuthal and rapidity trends of the global alignment provide a reference for interpreting data: trends inconsistent with these would challenge the simplest single homogeneous rotating-medium interpretation. We distinguish model-dependent numerical details from qualitative features stable within this model class.
The memory-burden effect was recently proposed to take into account the information back-reaction in the evaporation of primordial black holes (PBHs). In this work, we systematically explore the axion-like particle (ALP) production via the evaporation of memory-burdened PBHs and the subsequent ALP-photon conversion in cosmic magnetic fields. The PBH evaporation progress is divided in the semiclassical phase of Hawking radiation and the quantum memory-burden phase. The time evolution of PBH mass and the gamma-ray flux after the conversion of PBH-emitted ALP are then evaluated by considering the memory-burden induced PBH entropy suppression. Furthermore, we investigate the detection prospects of this evaporation-conversion signal in next-generation satellite telescopes, including AMEGO, e-ASTROGAM and MAST. The detectable PBH mass range is extended down to masses much smaller than $10^{15}$ g. Applying the Fisher forecasting method, we derive the projected sensitivity for PBH fraction $f_{\rm PBH}$ and ALP-photon coupling $g_{a\gamma\gamma}$.
We focus on gravitational waves (GWs) observable in pulsar timing array and interferometric searches that are produced by the annihilation of cosmic string-wall networks in axion-like particle (ALP) models. We called this process "catastrogenesis." It produces GWs with a characteristic peaked spectrum. These GWs would not be observable if the ALPs were stable. We thus assume that ALPs decay into two photons before Big-Bang nucleosynthesis (BBN). The large ALP-photon coupling required could induce field dissipation and friction on cosmic walls through interactions with the radiation background. We study the conditions under which these effects are negligible and map the parameter regions yielding observable GW signals onto the usual ALP mass-coupling parameter space. We find that, in these regions, ALPs dominate the energy density of the Universe before they decay, leading to a period of intermediate matter domination, which would leave a clear imprint on the GW spectrum.
The simultaneous determination of Parton Distribution Functions (PDFs) and fundamental physical parameters, e.g. the strong coupling constant $\alpha_s$, the mass of the top quark $m_t$, or Wilson coefficients of an Effective Field Theory operators, is essential for the high-precision physics programme of the Large Hadron Collider. Yet, simultaneous global fits face significant methodological and computational challenges, rooted in the fundamental tension between estimating a finite-dimensional parameter and an infinite-dimensional function. In this paper, we address this problem by introducing a semiparametric estimation framework. The key advantage of our approach is that it avoids the need to refit the PDFs in the presence of either modified SM parameters or BSM contributions. Starting from standard, decoupled estimates of the PDFs and physics parameters, the method computes a bias correction a posteriori via the efficient influence function, yielding a debiased one-step estimator of the finite-dimensional parameter along with uncertainties with valid frequentist coverage. This correction rigorously accounts for the interplay between PDF and physics parameters without requiring a computationally expensive joint fit. As a proof of concept, we apply the method to two toy scenarios preparatory to a realistic global fit: the extraction of a dimension-six SMEFT Wilson coefficient from Deep Inelastic Scattering (DIS) pseudo-data based on BCDMS measurements, isolating the non-singlet PDF combination $T_3$, and to the determination of the proton total valence $V$ from combined HERA measurements. Our results demonstrate that the one-step estimator successfully removes the bias inherent in a preliminary, decoupled estimate and achieves confidence intervals with correct nominal coverage, offering a statistically rigorous and computationally efficient alternative to full simultaneous PDF fits.
We revisit the two-loop parity-odd photon polarization analyzed by Boyarsky, Ruchayskiy, and Shaposhnikov [Phys. Rev. Lett. 109, 111602 (2012)]. The original calculation neglected opposite- fermion-flow partner diagrams for the tadpole and exchange-bubble topologies alike. We quantify the impact of the properly restored exchange-bubble coefficients on the static magnetic response.
The formalism of non-equilibrium dynamics for the dipole-symmetric $U(N)$ model involving $N$-component charged scalar fields is studied on the Schwinger-Keldysh contour by a systematic $1/N$ expansion of two-particle-irreducible (2PI) effective action to the next-to-leading order (NLO). The differential equations describing non-equilibrium evolution equations of two-point functions and field expectation values related to the symmetry breaking in the dynamics are derived, which encompass scatterings between modes essential in the late-time evolution and thermalization beyond the scope of the mean field. At the late-time regime of the evolution, the leading-order (LO) gradient expansion is performed to construct the vertex-resummed kinetic theory by encoding non-perturbative effects in the vertex through the resummation, which is distinct from the standard kinetic theory written by the weak-coupling expansion.
Low-threshold neutrino and dark-matter experiments constrain light mediators through different momentum transfers, targets, and coupling combinations. We examine scalar and vector interactions in coherent neutrino--nucleus scattering, neutrino--electron scattering, and dark-matter direct detection. Three representative interaction models are used to compare recoil spectra and coupling degeneracies. For $^{73}\mathrm{Ge}$ and $^{131}\mathrm{Xe}$, the nuclear-charge response matrix has a condition number of approximately 115, so two different targets may still leave nearly parallel blind directions. An analytic profile-likelihood calculation shows how spectral overlap and uncertainties in neutrino interactions affect dark-matter discovery sensitivity in the neutrino fog. We discuss the implications of measurements from COHERENT, CONUS+, LZ, XENONnT, and PandaX-4T and specify which theoretical inputs, detector responses, and statistical correlations are needed to combine their constraints. keyword : coherent elastic neutrino-nucleus scattering; light mediators; neutrino--electron scattering; dark matter direct detection; non-standard interactions; solar neutrinos; complementarity
We study back-to-back dijet production in deep inelastic scattering (DIS) at next-to-eikonal accuracy within the Color Glass Condensate framework, focusing on the quark-background contributions. We compute the quark-gluon and quark-antiquark production cross sections through next-to-leading power in the correlation limit for longitudinally and transversely polarized photons. In the quark-gluon channel, we derive both the kinematic corrections to the hard parts accompanying the twist-two quark distribution and the genuine twist-three contributions involving three-body quark-gluon-quark correlators. In the quark-antiquark channel, the interference of the eikonal amplitude with the double $t$-channel quark-exchange amplitudes probes three-body correlators with a different transverse arrangement of the fields. We express the results in terms of transverse momentum dependent (TMD) correlators and provide the corresponding hard coefficients. Our analysis extends the operator-level connection between the next-to-eikonal CGC framework and quark TMDs beyond leading power in the correlation limit.
Recent studies show that in addition to the flat spacetime, Integration-by-parts (IBP) relations and differential equations can also provide a systematic approach to Feynman integrals in de Sitter spacetime. dSIBP is a Mathematica package for the automated construction of IBP systems and differential equations. For dS integral families with massive and massless propagators, it generates a complete set of IBP seeds, assembles linear systems for external reduction, and constructs differential equations for the reduced master integrals. The implementation combines equations of motion, remaining terms and parity constraints, and provides reliable checks. We describe the conventions and public interface through worked examples.
In this work, we investigate the \(pp \to K^+ K^+ \Lambda \Lambda\) reaction using an effective Lagrangian approach and the isobar model. The calculation includes the exchange of \(\pi\), \(\eta\), \(\sigma\), \(\rho\), \(\omega\), and \(K\) mesons, as well as contributions from eight nucleon resonances: \(N(1535)\), \(N(1650)\), \(N(1710)\), \(N(1720)\), \(N(1895)\), \(N(1900)\), \(N(2060)\) and \(N(2120)\). The double-resonance excitation mechanism (\(NN \to N^* N^*\)) is found to dominate this reaction over the entire energy range considered. Among the exchanged mesons, the \(\eta\) exchange provides the largest contribution at lower energies, whereas the \(K\) exchange dominates at higher energies. Near the threshold, \(N(1535)\) and \(N(1650)\) play the most important roles, while at higher energies \(N(1710)\) and \(N(1720)\) become dominant. Due to isospin conservation, this reaction is predominantly coupled to nucleon resonances, providing a relatively clean channel for \(N^*\) spectroscopy. Our results indicate the unique potential of this reaction for studying nucleon resonances and provide a theoretical reference for future experimental studies at HIAF.
In this paper, a multivariate analysis based approach for enhancing the extraction of the rare Standard Model (SM) process being studied - Higgs boson production in association with a single top quark (tH) - from the prevailing background processes is presented. The analysis was performed using a Monte Carlo generated dataset simulating the outcomes of proton-proton collisions at the Large Hadron Collider (LHC). A deep fully connected neural network was developed for signal-background discrimination, incorporating a masking mechanism designed to suppress the contribution of input variables associated with objects that were not reconstructed in a given event. The performance of the masked architecture was evaluated on independent Monte Carlo samples. The results of the proposed methodology are compared with a conventional cut-based approach in terms of the statistical significance of the tH production channel. The developed framework was tested using a simulated dataset corresponding approximately to the combined statistical samples of LHC Runs 1, 2, and 3.
We study new physics effects on the decays of the standard model-like Higgs boson ($h$) and the Higgs trilinear coupling including the full one-loop corrections in the real Higgs triplet model (RHTM). We adopt the on-shell renormalization scheme, in which the scalar mixing angles are renormalized in a gauge-independent way using the pinch technique. We found that sizable one-loop effects can arise in the decay rates through the Higgs wave-function (external-leg) corrections, while the tree-level effects are rather small due to the constraint on the vacuum expectation value of the triplet field from the electroweak precision measurements. In addition, the $h\to\gamma\gamma$ decay rate and the $hhh$ coupling are sensitive to loop contributions. The RHTM may be distinguishable from other extended Higgs models by studying the correlations among the $h\to\tau\tau$, $h\to ZZ^{*}$, and $h\to\gamma\gamma$ decay modes, and such characteristic predictions can be tested at the High-Luminosity LHC or future Higgs factories.
Baryon-to-meson enhancements are commonly compared across collision systems at equal multiplicity. Using published data only, we test whether the $p_T$ dependence of the CMS $\Lambda/K^0_S$ ratio in minimum-bias O-O collisions at $\sqrt{s_{NN}}=5.36$ TeV can be obtained from CMS multiplicity-differential p-Pb and Pb-Pb measurements weighted with the O-O multiplicity distribution. The prediction from p-Pb collisions of equal multiplicity is harder than the data, with a tilt of $+0.35\pm0.04$ in $\ln(\mathrm{prediction}/\mathrm{data})$ versus $\ln p_T$, whereas that from peripheral Pb-Pb collisions is consistent with the data. In a Glauber model calibrated on O-O data, O-O and peripheral Pb-Pb collisions of equal multiplicity have similar transverse densities $\rho=\langle(dN_{ch}/d\eta)/S_\perp\rangle$, about half of that in p-Pb. Matching the p-Pb reference in $\rho$ instead of multiplicity reduces the tilt by about 60%, to $+0.14\pm0.04$, with nucleons as sources; the tension is fully removed ($-0.02\pm0.04$) only when sub-nucleonic structure is included (three constituents per nucleon), so the conclusion depends on the modeled size of high-multiplicity p-Pb collisions. The published blast-wave velocities of p-Pb and Pb-Pb collisions, which differ at equal multiplicity, are close at equal $\rho$. Multiplicity alone thus does not determine the $\Lambda/K^0_S$ shape across systems; the data are consistent with a radial boost governed by the transverse density, as expected from hydrodynamics. The same pattern is found in EPOS4, which has a hydrodynamic core, but not in PYTHIA Angantyr. For Ne-Ne collisions, which have the transverse density of O-O at equal multiplicity, the minimum-bias ratio is predicted to agree with O-O within 3-5%, as EPOS4 also predicts.
The annual modulation reported by the DAMA/LIBRA collaboration remains in tension with the null results of other direct-detection experiments. We investigate the compatibility of DAMA/LIBRA with LZ, PICO-60 and CDMSlite within a generalized non-relativistic effective field theory (EFT) framework. In addition to the EFT operator expansion we investigate additional modifications to the standard WIMP picture, including inelastic scattering, variations in the NaI quenching factors, and a rescaling of the dark-matter velocity dispersion. We perform a Markov chain Monte Carlo analysis in this extended model space, using two alternative approaches to the likelihood function describing the DAMA/LIBRA data. Both approaches result in strong discrepancy between the data from DAMA/LIBRA and other experiments. We conclude that the extended model space considered here cannot accommodate the DAMA/LIBRA signal while remaining consistent with the non-observation of dark matter in other experiments.
We present the first complete next-to-leading-order (NLO) QCD calculation of the fully charm tetraquark radiative decays $T_{4c}(0^{++},2^{++})\to\gamma J/\psi$ and $T_{4c}(1^{+-})\to\gamma\eta_c$ at leading order in the relative velocity. The NLO widths are $2.3$--$3.1$ times the leading-order (LO) widths for the long-distance matrix element (LDME) inputs considered here, with $m_c=1.5$ GeV and $\mu_R=2m_c$. In the scalar channel, the NLO corrections change the relative contributions of the two color-spin components and their interference. For the tensor channel, the longitudinal fraction $f_L$ of the daughter $J/\psi$ changes from $0.11$ at LO to $0.18$ at strictly expanded NLO, with sensitivity to higher-order corrections. These NLO results provide valuable theoretical input for searches for states predicted below their respective lowest dicharmonium thresholds and for probing the spin and short-distance structure of observed tetraquark candidates.
Charge-Parity Violation (CPV) is expected in three-body charm decays. In particular, in the singly Cabibbo suppressed decay process $D^+ \to K^-K^+\pi^+$; in which an amplitude analysis is required to understand the dynamics of Final State Interactions (FSI) and the mechanism that can generate CPV. In this work, we show the prospects of analysing recent data from the Large Hadron Collider beauty (LHCb) experiment at CERN, with a precise theoretical model expected to reveal CPV mechanisms. Previous analyses of the $D^+ \to K^-K^+\pi^+$ decay were unable to satisfactorily describe the data using the Isobar Model. Currently, LHCb has a sample of charmed meson decays with around 100 million events for the $D^+ \to K^-K^+\pi^+$ decay, so a more robust phenomenological model is needed to describe such a large data set. The present model has allowed the inclusion of hadronic FSI and will, in prospect, introduce three-body effects, overcoming some limitations of the Isobar Model, and has all factors necessary to reveal the presence of CPV. To do so, it factorizes the weak vertex separated in leading topologies and relies on extensions of Resonant Chiral Perturbation Theory to describe FSI. As a proof-of-concept, a toy dataset of the S-wave of the most recent amplitude analysis of $D^+ \to K^-K^+\pi^+$, by the CLEO-c collaboration, was fitted with this model. From fits to model-independent parametrizations of scattering amplitudes, the parameters of the FSI amplitudes were fixed, and the production parameters of the weak vertex were then obtained from the fit to the toy dataset, yielding a good agreement between the data and our model.
Topological fluctuations in the quark-gluon plasma can generate local chiral imbalances whose spatial coherence remains difficult to access with conventional charge-separation measurements. We propose differential hyperon-pair spin correlations as a probe of both the strength and spatial organization of these fluctuations. Fluctuations of the axial chemical potential $\mu_5$ can induce pair correlations even when the mean helicity polarization vanishes. Using the AMPT model, we find that the magnitude of the hyperon spin correlation probes the magnitude and spatial coherence scale of $\mu_5$, while the ratio of short- and long-range correlations varies strongly with the spatial coherence scale, but only weakly with $\mu_{5}$ over the range of explored parameters. These observables provide an experimentally testable strategy for constraining the spatial structure of chiral-imbalance fluctuations.
We perform a NNLO perturbative QCD analysis for exclusive double charmonium production $e^+e^-\to J/\psi+\eta_c$ within the NRQCD factorization formalism using the Principle of Maximum Conformality (PMC). It is well known that this charmonium process suffers poor pQCD convergence, as well as large renormalization scale uncertainty. The PMC is used to remove conventional renormalization scale uncertainty. Based on two fundamental physical processes of charmonium, $J/\psi\rightarrow e^+e^-$ and $\eta_c\rightarrow\gamma\gamma$, and using the NNLO perturbative results together with experimental measurements, we extract the factorization-scale-dependent long-distance matrix elements for $J/\psi$ and $\eta_c$. Combining these two matrix elements with the factorization-scale-dependent short-distance coefficient, we obtain predictions that are independent of the factorization scale for the $e^+e^-\to J/\psi+\eta_c$ process. Our predictions agree with the measurement from the BaBar collaborations within errors. Remarkably, we provide a new way to eliminate conventional renormalization and factorization scale ambiguities for the $e^+e^-\to J/\psi+\eta_c$ process. We further demonstrate that the slow convergence of the pQCD series is an intrinsic property of this double-charmonium process.
Chiral anomalies offer a fundamental probe of the quantum structure of gauge theories and their underlying symmetries. In this paper, we introduce a framework to characterize the chiral anomaly in two dimensions directly at the diagrammatic level. To this end, we establish a consistent prescription for handling $\gamma^5$ in dimensional regularization at $d=2$. On this basis, we derive an expression for the fully generic chiral anomaly directly from the contributions of the bubble and triangle diagrams, either in the massless or massive case. Then, we show that the different forms of the anomaly can arise from appropriate choices of parameters directly at the level of this master expression. Overall, $d=2$ is shown to provide an excellent environment to investigate chiral anomalies at the amplitude level: Ward identities are demonstrated rigorously and to arbitrary order in the mass expansion without further approximation, resulting in an unprecedented degree of control on the anomaly.
Whether a sterile neutrino mixes with the three active ones remains an open question. Its mixing with the tau neutrino, $|U_{\tau 4}|^2$, is the least constrained, since terrestrial experiments probe it only indirectly and over limited ranges of sterile-neutrino mass. We show that TeV-PeV astrophysical neutrinos probe it differently. Their sources make almost no $\nu_\tau$, but oscillations over cosmological distances turn about one third of them into $\nu_\tau$ before they reach Earth. Mixing with a sterile neutrino would make these $\nu_\tau$ scarcer, lowering the $\nu_\tau$ fraction that neutrino telescopes measure, whatever the sterile-neutrino mass. In contrast, sterile mixing with $\nu_e$ or $\nu_\mu$ is nearly undetectable. Fitting the flavor composition measured by IceCube, with the composition at the sources left free, we find $|U_{\tau 4}|^2 < 0.88$ at 90% C.L. Combining IceCube with present and planned neutrino telescopes, including IceCube-Gen2 and HUNT, could lower this limit to 0.24-0.29 by 2040 and to 0.12-0.14 by 2050. By 2050, these limits would match some present terrestrial limits, though not the strongest.
We study cold, electrically neutral, beta-equilibrated quark matter with u, d, and s quarks described by a symmetry-preserving contact interaction whose parameters are fixed in vacuum. The vector repulsion is varied as a fraction 0 < eta < 3/2 of the scalar coupling, and results are given with and without the flavor dressing of the effective coupling. Pure quark matter is not self-bound in this model, and no value of eta produces a star that reaches two solar masses while satisfying the tidal constraint from GW170817; the heaviest configurations owe their mass to an envelope of constituent quarks. We then construct hybrid stars with a relativistic mean-field hadronic phase fitted to GM1 saturation properties, using both Maxwell and Gibbs constructions and a deconfinement bag shift. Tying deconfinement to chiral restoration and requiring a continuous pressure yields an upper bound on this shift. Within that bound, quark matter appears inside stable stars only for eta < 1/2, never below about 4 n0, and only in stars between 2.2 and 2.35Msun, over a stable mass window of at most 0.02Msun. The vector strength that pure quark stars need to become massive prevents deconfinement in hybrid stars. Radii and tidal deformabilities of intermediate-mass stars are therefore set by the hadronic EoS alone; with the softer SLy4 EoS the transition moves to the maximum-mass configuration itself.
An important physical quantity that is part of the Saha ionisation equation is the partition function of the neutral hydrogen atoms. An immense uncertainty is caused by the divergency of the neutral atom partition function arising due to the fast growing degeneracy factor of its excited n-state. We suggested a regularisation and renormalisation procedure for the partition function of the neutral hydrogen atoms. The renormalised partition function is well defined and allows to calculate the population of the energy levels and the ionisation state of the hydrogen plasma as a function of its temperature and pressure. In the low-temperature limit the behaviour of these functions smoothly transforms to the Saha equation, which is used in the description of the low-temperature plasma. At higher temperatures the renormalised ionisation equation describes the deviation from the Saha equation. The application of the renormalised ionisation equation to the solar core and atmosphere is considered.
In this paper, we investigate the classical properties of a non-linear electrodynamics that emerges from one loop effective action for fermions coupled to an antisymmetric background tensor, that breaks the Lorentz symmetry in the model. The conservation laws are obtained through the Belinfante-Rosenfeld energy-momentum tensor in the non-linear electrodynamics that provides the energy density, the Poynting vector, the linear momentum and the stress tensor. In particular, this Lorentz symmetry violation breaks the symmetric index of the energy-momentum tensor, but it preserves the gauge invariance, as we expect. We introduce the prescription of a magnetic background field, that we consider constant and uniform. For propagation effects, the model is linearized by the magnetic background. This prescription allows us investigations of the plane wave propagation in the presence of an external magnetic field. In this context, we obtain the constitutive relations of the material medium, that behaves like an bi-anisotropic medium. Thereby, we calculate the refractive index whose one of the solutions show the total absorption of the wave in the medium. Using the wave equation for linear polarization, we investigate the birefringence phenomenon when the linear wave polarization changes with the magnetic background direction. The birefringence is so related to one of the spatial component of the LSV tensor in which we estimate through the PVLS experiment. We use one of the dispersion relations to obtain the kinematic of the Compton effect in the presence of the LSV parameter.
Coherent elastic neutrino--nucleus scattering (CE$\nu$NS) offers a low-energy probe of the weak mixing angle, $\sin^2\theta_W$, and possible new physics in the neutrino sector. Its reliable interpretation, however, requires independent constraints on the neutron distributions of the target nuclei. We exploit correlations across nuclei within an extended Skyrme energy-density-functional framework to propagate constraints from the CREX and PREX-II parity-violating electron-scattering (PVES) measurements to CE$\nu$NS targets. This yields neutron form factors and radii, with relative radius uncertainties below $1\%$. Using these inferred neutron form factors, we jointly analyze the COHERENT CsI, Ge, and Ar data and obtain $\sin^2\theta_W=0.231^{+0.016}_{-0.015}$, consistent with the Standard Model prediction. These results provide the first electroweak-experimentally constrained benchmarks for nuclear-structure studies, neutrino-sector electroweak tests, and CE$\nu$NS signal predictions in dark-matter detectors.
The empirical success of non-extensive Tsallis statistics and multisource thermal models in describing transverse-momentum (pT ) spectra and rapidity distributions in high-energy relativistic collisions highlights a deep connection between expansion geometry, non-extensive thermodynamics, and QCD dynamics. In this work, we establish a theoretical framework showing that the thermofractal structure of QCD phase space provides a direct microscopic foundation for the multisource thermal model. By exploiting the Euler integral representation of non-extensive statistical factors, we demonstrate that a single thermofractal emission source generating q-exponential distributions is mathematically equivalent to a continuous superposition of local Boltzmann thermal sources whose temperature fluctuations follow an inverse-Gamma distribution. Furthermore, we prove that multi- component phenomenological fits with discrete source temperatures represent the exact, optimal Gauss-Laguerre quadrature discretisation of this underlying continuous thermofractal field. We show how this continuous field constrains the temperature parameter space in multisource formulations, matches pQCD hard-scattering power-law asymptotics, and provides a robust vacuum baseline for medium-induced jet quenching and nuclear modification factor (RAA ) calculations.
The Gaia mission has greatly improved our understanding of the stellar binary population. Beyond providing an extensive catalog of binary systems with two luminous stars, Gaia has also discovered several systems that appear to be star--black hole (BH) binaries. One of the leading candidate formation channels for these systems is dynamical exchange, in which one component of a star--star binary is ejected from the system and replaced by a BH. Exchange processes are very sensitive to the velocity distribution of the incoming objects, and become very efficient in the limit that perturbers are slow, so the exchanged binary population is a sensitive probe of slow-moving objects. A population of slow-moving, nonluminous objects is naturally produced in dissipative dark matter (DDM) scenarios, where a subcomponent of dark matter can cool to form a dark disk and dark compact objects (DCOs), including but not limited to BHs, with a small velocity dispersion. In this work, we evaluate the rate at which DCOs formed by DDM exchange into star--star binaries to form star--DCO binaries. We find that in a wide range of parameter space, even under conservative assumptions, the rate of exchange interactions is sufficient to produce the objects that Gaia has observed to date. In some portions of parameter space, the predicted exchange rate is well in excess of the rate estimated from observations. We point out the potential for competitive constraints on the DDM parameter space with current and future data, making the Gaia mission an important testbed for dark sector cooling.
The recent discoveries of high-redshift quasars at $z\sim6-10.1$ present a challenge to conventional supermassive black hole (SMBH) formation scenarios: their central SMBHs are too large to have grown from early stellar remnants, even under efficient super-Eddington accretion. An alternative approach is the direct collapse of primordial, dust- and metal-free gas clouds into black hole seeds as early as $z\sim20$. To prevent fragmentation from highly efficient molecular hydrogen cooling and allow such a collapse, a strong flux of UV photons is required to photodissociate molecular hydrogen, suppressing star formation. We investigate whether the decay or annihilation of dark matter with masses below $\sim200$ eV can produce sufficient UV radiation, both from the cosmological background and within early dark matter halos. Using thermal simulations of a one-zone primordial gas cloud model with the Grackle chemistry and cooling library, we map the resulting gas behavior across a range of dark matter lifetimes, cross sections, and masses. From this, we determine regions of parameter space where direct collapse into an SMBH is possible and the corresponding maximum halo mass required.
The ATOMKI anomalies motivate the possibility of a new particle, the X17, with a mass of 17 MeV and weak couplings to nuclei and electrons. Such a particle may be produced at the LHC, travel 480 m in the far-forward direction, and decay to $e^+e^-$ in FASER. In this paper, previous FASER searches for dark photons and axion-like particles (ALPs) are combined and interpreted as searches for a candidate X17 particle, the protophobic vector boson. The searches use data collected from $pp$ collisions at $\sqrt{s} = 13.6$ TeV in LHC Run 3 from 2022 for the dark photon search and from 2022-2023 for the ALP search. No excess events are found above the expected background, and the combined null results exclude a previously-unconstrained "low-coupling window" with electron coupling $6 \times 10^{-5} < \epsilon_e < 1.2 \times 10^{-4}$. A "high-coupling window" remains.
We derive the basic equations suitable for the coupled fluid--spacetime eigenvalue problem from the second-order action in full general relativity and accurately determine quasi-normal modes of a variety of rapidly rotating stars with outgoing-wave boundary conditions. For MIT-bag strange stars, the spectrum realizes Chandrasekhar's instability picture, with distinct Chandrasekhar--Friedman--Schutz and Jacobi-like neutral conditions and the transition to dynamical bar-mode growth. For neutron stars, we determine the $f$-, $r$-, and other inertial-mode spectra and their radiative damping or growth times. Interactions between $f$- and inertial modes reveal avoided crossings and exchanges for radiative damping or growth rates. We locate quasiradial collapse thresholds through a static stability analysis and independently verify them by tracking the fundamental $F$-mode frequency to zero, clarifying that the central density at the onset of the dynamical instability is always larger than that of the secular instability for uniform rotation. Our formalism and numerical implementation can also resolve highly damped $w$-modes.
We present a systematic study of the spin evolution of accreting black holes. Using the BHAC code for general relativistic magnetohydrodynamic simulations, we conduct a total of 500 high resolution simulations of magnetized accretion disks around Kerr BHs with spin parameters ranging from $\chi=0$ to $\chi = 0.99$. The baseline configuration follows the default Fishbone--Moncrief torus setup in BHAC. We further explore the effects of: I) introducing multiple poloidal magnetic loops, II) the initial position of the torus, III) magnetic field strength and IV) radial loop modulation. From each simulation we extract the mass flux and angular momentum flux through the horizon to compute the time-averaged spin evolution rate after the system becomes quasi-stationary. The equilibrium spin ranges from $\chi_{\rm eq}\simeq0.88$ in the fiducial model to $\chi_{\rm eq}\simeq0.98$ for weak-flux model. Applied to Sgr A$^*$, even an optimistic estimate for rapid spin evolution gives a timescale longer than $10^{13}$ yr, indicating an earlier growth or merger history. These trends are consistent with the picture that larger net magnetic flux threading the horizon enhances jet-torques and reduces the equilibrium spins, whereas weak net flux yields near-maximal spins. Our results provide a pathway to interpret the high spins reported for X-ray binaries and active galactic nuclei and they sharpen the astrophysical viability of near-horizon high-energy processes that rely on near-extremal black holes.
We study photon dispersion in the presence of a strong external magnetic field for propagation both perpendicular and parallel to the field, considering (i) the magnetized QED vacuum and (ii) a magnetized electron-positron medium at finite density (nonzero chemical potential). The analysis is performed in one-loop QED at finite temperature and density, and we extract polarization-dependent dispersion relations and phase velocities from the eigenmodes of the photon polarization operator. Using these phase velocities, we estimate propagation-induced time delays for photons emitted from neutron stars in the strong-field regime, adopting a simplified magnetosphere model with a toroidal magnetic field geometry and a radially varying chemical potential profile in the degenerate limit. We compare the predicted delays with observational timing constraints and discuss how strong-field QED and plasma corrections can generate measurable departures from the light cone, with potential signatures relevant for magnetars and modern polarimetric and timing observations. It should be noted that the time-delay estimates derived here are based on the phase velocity and serve as indicative order-of-magnitude predictions.
Recent light-ion collisions at the Large Hadron Collider provide an opportunity to investigate the system-size dependence of hydrodynamization and whether the structure of light nuclei can be extracted from collective flow data. Both objectives require an accurate understanding of how the collision dynamics converts initial-state geometry into final-state momentum anisotropies. To this end, and to assess the impact of the experimental results, we compare simulations of O+O and Ne+Ne collisions in hydrodynamic and kinetic theory simulations across opacities. In both ultracentral and peripheral collisions, Ne+Ne-to-O+O elliptic flow ratios are robust against changes in dynamical description, supporting interpretations of data based on nuclear-geometry-driven effects. Triangular-flow ratios instead show substantially stronger sensitivity to nonequilibrium dynamics.