Thu·Nov 27, 2025Thursday·November 27, 2025

1. 01*

   Discovery prospects for photophobic axion-like particles in the $WWjj$ final state at the High-Luminosity LHC

   Jiaojiao Feng🇨🇳 · Ying-nan Mao🇨🇳 · Kechen Wang🇨🇳

   We evaluate discovery prospects for photophobic axion-like particles (ALPs) in the $WWjj$ final state at the High-Luminosity LHC (HL-LHC; $\sqrt{s}=14$ TeV, $L=3$ ab${}^{-1}$). In the photophobic limit ($g_{a\gamma \gamma }=0$), ALPs couple to electroweak gauge bosons and are produced in association with two jets ($pp\to jja$) via both $s$-channel electroweak exchange and vector-boson-fusion (VBF)-like topologies, followed by $a\to W^{+}{W}^{-}$ decay. We target the different-flavour dilepton mode $W^{+}{W}^{-}\to e^{\pm }{\mu }^{\mp }\nu \bar{\nu }$ with two jets and moderate missing transverse momentum. The analysis employs a two-step strategy: an initial preselection that defines the signal-like final state, followed by a multivariate analysis (MVA) trained on dijet and dileptonic-$WW$ kinematics from both the $s$-channel and VBF-like production mechanisms to separate signal from background; the MVA threshold is optimized independently at each $m_a$. We present $2\sigma$ and $5\sigma$ discovery sensitivities for the ALP-$W$ coupling $g_{aWW}$ across the $170$--$4000$ GeV mass range. For $260$ GeV $\le m_a\le 1500$ GeV, the $2\sigma$ ($5\sigma$) sensitivity is approximately flat around 0.61 (0.76) TeV${}^{-1}$. We also report model-independent discovery thresholds for the fiducial quantity $\sigma (pp\to jja)\mathrm{Br}(a\to W^{+}{W}^{-})$ over the same mass range to enable reinterpretation for other models. These results indicate that the $WWjj$ topology offers competitive and complementary sensitivity to heavy photophobic ALPs at the HL-LHC.

   hep-phhep-exCPC(2026)·5 citations
2. 02*

   Exotic-interaction searches on small scales via near-threshold enhancement

   Runqi Kang🇨🇳 · Xing Rong🇨🇳

   Exotic interactions between fermions mediated by new bosons beyond the Standard Model may hold the key to several fundamental conundrums on the frontier of physics.However, laboratory searching for exotic interactions on small length scales is fundamentally held back by the short force range.Here we propose that the force range of exotic interactions tends to infinity when the oscillation frequency of exotic interactions approaches the mass of the new bosons, i.e., the new bosons become nearly on-shell. This is named as the near-threshold enhancement. Through the near-threshold enhancement, even fermions at distances larger than the original force range can make considerable contributions to exotic interactions. Therefore, the size of the experimental apparatus can break the limitation of the force range, and thus both the signal of exotic interactions and the sensitivity of sensors can be greatly enhanced. We also propose a method to search for the exotic interactions in the mass range between 80 $\mu$eV and 800 $\mu$eV taking advantage of the near-threshold enhancement. For the coupling $g_{\mathrm{A}}^{\mathrm{e}}{g}_{\mathrm{A}}^{\mathrm{e}}$, we expect an improvement on its upper bounds of 10 orders of magnitude at 800 $\mu$eV. This method can be further extended to enhance the search for other types of exotic interactions and boost the study of new physics beyond the Standard Model.

   hep-phhep-exPRD(2025)·2 citations
3. 03*

   Neutral Magnetic Monopole in the Standard Model

   Y.M. Cho🇰🇷

   The standard model has the electroweak monopole which has the magnetic charge $4\pi /e$, as a hybrid between the Dirac and 'tHooft-Polyakov monopoles. We argue that it may have new type of monopoles, in particular the neutral monopole (``the Z monopole") which is electromagnetically neutral but has the neutral magnetic charge $4\pi /\text{be}$, where $\text{be}$ is the neutral charge. The mass of the new monopole could be less than the Cho-Maison monopole, around 3.28 TeV. We show how to construct the neutral monopole and clarify the origin of the topology of the new monopole. We discuss the implications of the new monopoles in physics.

   hep-phhep-th2 citations
4. 04*

   Exploring muonphilic dark matter with the $Z_2$-even mediator at muon colliders

   Wanyun Chen🇨🇳 · Haoqi Li🇨🇳 · Chih-Ting Lu🇨🇳 · Qiulei Wang🇨🇳

   The Galactic Center GeV Excess (GCE) remains a compelling but enigmatic signal from the inner region of our galaxy. Muonphilic dark matter (DM), which couples exclusively to muons via a new mediator, provides a viable explanation for the GCE and relic density while naturally evading constraints from direct detection, collider searches and other multi-messenger observations. Based on the viable non-resonant parameter space identified in previous global fits, we perform a comprehensive study exploring the prospects for discovering such muonphilic DM in the context of a future $3$ TeV muon collider, focusing on simplified models with a $Z_2$-even mediator. Four distinct search strategies are investigated: visible on-shell mediator decays (${\mu }^{+}{\mu }^{-}\gamma$ final state), invisible on-shell mediator decays (mono-photon plus missing energy), mono-photon production via off-shell mediators, and vector boson fusion production.Through a detailed signal-background analysis using cut-and-count methods, we project the exclusion limits at $95\%$ confidence level for seven representative models across a wide range of mediator masses. Our results demonstrate that the projected limits cover a significant portion of the viable parameter space that explains the GCE, establishing a muon collider as a decisive machine for testing the muonphilic DM hypothesis.

   hep-phhep-exCPC(2026)·2 citations
5. 05*

   Effective LFV couplings at the electron-proton collider

   Hrishabh Bharadwaj🇮🇳 · Sukanta Dutta🇮🇳

   We estimate the accuracy with which the coefficient of the lepton flavour-violating dimension-six operators can be measured at the proposed electron-proton collider. Cuts-based analysis is performed to compute the signal significance at the centre of mass energy of 1.3 TeV, with a total integrated luminosity upto $\sim$ab${}^{-1}$. Using the optimal observables method for the kinematic distributions, we study the sensitivity of the effective couplings. We also study the impact of the initial electron beam polarisation.

   hep-phPoS(2025)·0 citations
6. 06*

   Production of excited ${\Lambda }_c^{+}$ baryons through ${\Lambda }_b$ hadronic weak decays

   Kai-Lei Wang🇨🇳 · Ya-Mei Cao🇨🇳 · Hui-Xiao Duan🇨🇳 · Xian-Hui Zhong🇨🇳

   In this work, to establish a more abundant ${\Lambda }_c$ baryon spectrum, we discuss the production potentials of the excited ${\Lambda }_c$ baryons through ${\Lambda }_b$ hadronic weak decays within a constituent quark model. Based on our successful explanations of the existing experimental data for the ${\Lambda }_b\to {\Lambda }_c({\pi }^{-},K^{-},D^{-},D_s^{-},D_s^{\ast -})$ processes, we further calculate the decay rates of the ${\Lambda }_b$ baryon into the $1P$-, $1D$-, $2S$-, $3S$-, $2P$-, $1F$-, and $2D$-wave ${\Lambda }_c$ excited states. It is found that these ${\Lambda }_c$ excitations have a large production rate in the ${\Lambda }_b$ hadronic weak decay process associated ${\pi }^{-}$ meson emitting, i.e., ${\Lambda }_b\to {\Lambda }_c^{\ast }{\pi }^{-}$, their branching fractions can reach up to $\mathcal{O}(10^{-3})$. To search for the higher $3S$-, $2P$-, $1F$-, and $2D$-wave ${\Lambda }_c$ states, the ${\Lambda }_b\to {\Lambda }_c(3S){\pi }^{-}\to D^{\ast 0}p{\pi }^{-}$, and ${\Lambda }_b\to {\Lambda }_c(2P,2D,1F){\pi }^{-}\to D^{(\ast )0}p{\pi }^{-}$ decays are worth observing in future experiments.

   hep-phPRD(2026)·2 citations
7. 07*

   Bayesian analysis of the complex singlet model with phase transition gravitational waves

   Qingyuan Liang🇨🇳 · Ligong Bian🇨🇳 · Huai-Ke Guo🇨🇳 · Yongcheng Wu🇨🇳

   We explore the prospects of probing the complex singlet extension of the Standard Model (CxSM) with gravitational waves from the electroweak phase transition. The study establishes a connection of the scalar potential parameters, the thermodynamic properties of the phase transition, with the directly measured stochastic gravitational-wave background in the presence of astrophysical background and foreground. Considering the space-based gravitational-wave detector Taiji, we construct a frequency-domain likelihood that incorporates instrumental and astrophysical noises, and we perform both Fisher-matrix forecasts and Bayesian nested sampling analysis. The comparison of these two approaches demonstrates consistent parameter recovery and highlights the sensitivity of Taiji to millihertz gravitational-wave signals. We further propagate the inferred constraints on the gravitational-wave spectrum back to the underlying CxSM parameters, obtaining meaningful limits on the Higgs self-couplings. The results emphasize the complementarity between gravitational-wave observations and collider measurements, showing that future missions such as Taiji can serve as a powerful probe of electroweak-scale new physics and the dynamical origin of the Higgs sector.

   hep-phastro-ph.HEgr-qcPRD(2026)·4 citations
8. 08*

   Freeze-in at Low Reheating and Direct Detection of Fermion Dark Matter

   Amir Amiri🇮🇷 · Bastian Diaz Saez🇨🇱 · Kilian Möhling🇩🇪

   We investigate a low-reheating-temperature freeze-in scenario within a minimal model of fermionic dark matter interacting through a pseudoscalar mediator. In this setup, dark matter is produced via the decay of the pseudoscalar, which remains in thermal equilibrium with the Standard Model bath. We derive the thermalization and non-thermalization conditions for the new fields and obtain the corresponding direct-detection constraints and projections on the model based on LZ and DARWIN experiments, respectively.

   hep-ph3 citations
9. 09*

   Cosmological Probes of Lepton Parity Freeze-in Dark Matter: $\Delta N_{\mathrm{eff}}$ & Gravitational Waves

   Ernest Ma🇺🇸 · Partha Kumar Paul🇮🇳 · Narendra Sahu🇮🇳

   In the canonical type-I seesaw mechanism for neutrino masses, a residual symmetry known as lepton parity: $(-1{)}^L$, remains preserved. Introducing a Majorana fermion $S$ with even lepton parity renders it naturally stable, making it a viable dark matter (DM) candidate. The addition of a lepton parity odd singlet scalar $\sigma$ allows for the coupling $NS\sigma$, where $N$ is the right-handed neutrino. If $S$ is not thermalized, then DM relic can be produced in two distinct ways: (i) for reheating temperature, $T_{\mathrm{rh}}>m_N$, dominantly through the decay of $N$ ($N\to S\sigma$), and (ii) for $T_{\mathrm{EW}}<T_{\mathrm{rh}}\ll m_N$, via standard model Higgs ($h$) decay ($h\to SS$ at one loop). If the $\sigma -h$ quartic coupling is large, then it can lead to a strong first-order electroweak phase transition even if $⟨\sigma ⟩=0$. Alternatively, if $\sigma -h$ coupling is small, then $\sigma$ can freeze out with a larger abundance, and hence its decay ($\sigma \to S\nu$) at late epochs can give rise to additional relativistic degrees of freedom ($\Delta N_{\mathrm{eff}}$). Thus, the framework gives a viable DM with mass range varying from MeV to TeV and leaves observable imprints, via gravitational waves and $\Delta N_{\mathrm{eff}}$, which offer complementary probes, potentially detectable in future gravitational wave and CMB experiments.

   hep-phastro-ph.CONPB(2026)·2 citations
10. 10*

    Updated bounds on the (1,2) neutrino oscillation parameters after first JUNO results

    Francesco Capozzi🇮🇹 · Eligio Lisi🇮🇹 · Francesco Marcone🇮🇹 · Antonio Marrone🇮🇹 · Antonio Palazzo🇮🇹

    Within the standard $3\nu$ framework, we discuss updated bounds on the leading oscillation parameters related to the $({\nu }_1,{\nu }_2)$ states, namely, the squared mass difference $\delta m^2=m_2^2-m_1^2$ and the mixing parameter ${\sin }^2{\theta }_{12}$. A previous global analysis of 2024 oscillation data estimated $\delta m^2$ and ${\sin }^2{\theta }_{12}$ with fractional $1\sigma$ errors of about $2.3\%$ and $4.5\%$, respectively. First we update the analysis by applying the latest SNO+ constraints, that slightly shift the $(\delta m^2,{\sin }^2{\theta }_{12})$ best fits. Then we apply the constraints placed by the first JUNO results, that significantly reduce the uncertainties of both parameters. Our updated global bounds (as of 2025) can be summarized as: $\delta m^2/10^{-5}{\mathrm{eV}}^2=7.48\pm 0.10$ and ${\sin }^2{\theta }_{12}=0.3085\pm 0.0073$ (with correlation $\rho =-0.20$), corresponding to $1\sigma$ uncertainties as small as $1.3\%$ and $2.4\%$, respectively. We also comment on minor physical and statistical effects that, in the future, may contribute to lift the current mass-ordering degeneracy of $(\delta m^2,{\theta }_{12})$ estimates.

    hep-phhep-exnucl-exPRD(2026)·24 citations
11. 11*

    Nuclear Detonations as Probes of Hidden Superluminal Sectors

    Karl Svozil🇦🇹

    We propose a highly speculative phenomenological framework in which nuclear detonations and high-energy collisions serve as probes for hidden sectors with effective superluminal propagation. Motivated by analogies between acoustic and electromagnetic phenomena, we stratify the physical description into three layers: a fundamental ``substrate'' layer, hidden-sector fields with extended causal cones, and the emergent Standard Model. We posit that the extreme, macroscopic stress-energy gradients generated by nuclear explosions might excite substrate or hidden modes that remain kinematically inaccessible to standard laboratory probes. This work unifies various exotic proposals -- including extra-dimensional shortcuts and trans-metric shockwaves -- into a single formalism, discussing the constraints imposed by causality and observation while outlining how such distinct high-energy regimes could complement one another in searching for physics beyond the emergent metric.

    hep-ph0 citations
12. 12*

    A Comprehensive Study of WIMP Models Explaining the Fermi-LAT Galactic Center Excess

    Chuiyang Kong🇺🇸 · Mattia Di Mauro🇮🇹

    The Galactic Center excess (GCE) of GeV $\gamma$ rays may hint at dark matter (DM), yet its origin remains debated. Motivated by this, we survey weakly interacting massive particle (WIMP) models that can fit the GCE while satisfying relic-density, direct-detection (DD), and indirect-detection (ID) bounds. We group candidates into hadronic (Higgs portals; simplified scalar/vector mediators), leptonic ($U(1{)}_{L_i-L_j}$), and mixed ($U(1{)}_{B-L}$, $Z$-portal) classes. Across all cases, present DD and dwarf-spheroidal $\gamma$-ray limits exclude wide regions, leaving mainly narrow resonant funnels with $m_{\mathrm{DM}}\simeq m_{\mathrm{med}}/2$ and portal couplings $\ll 1$. In hadronic setups, scalar and vector Higgs portals survive only in a thin strip near $m_h/2\simeq 62.5$ GeV with portal couplings $\sim 10^{-4}$, while the Dirac Higgs and $Z$ portals are essentially excluded. The UV-complete vector Higgs portal retains resonant bands whose viable portal strength depends on the mixing angle. Simplified scalars allow small windows for complex-scalar or vector DM; Dirac DM is strongly disfavored, whereas a pseudoscalar with Dirac DM remains viable over a broader parameter range. For a simplified $Z^{\prime }$ mediator, a pure vector coupling leaves only a marginal region, while pure axial is excluded by DD/ID bounds. In leptonic scenarios, inverse-Compton emission is essential: $L_{\mu }-L_e$ (and, to a lesser extent, $B-L$) fits the GCE with near-thermal cross sections, while $L_{\mu }-L_{\tau }$ is disfavored. Overall, viable WIMP explanations are constrained to finely tuned resonant regime, with leptophilic vectors and pseudoscalar portals emerging as the most robust options.

    hep-phastro-ph.HEPRD(2026)·9 citations
13. 13*

    $B\to K+invisible$ in a model with axion-like particles

    Xiyuan Gao🇩🇪

    The localized excess of $B\to K+\text{invisible}$ events reported by Belle-II is commonly interpreted as a signal for $B\to Ka$, where $a$ is an axion-like particle (ALP). In these proceedings, we summarize two theoretical updates regarding the $b\to sa$ decay amplitude within a minimal UV-complete model for invisible ALPs, namely the DFSZ model. (i) Contributions from certain two-loop diagrams can dominate the one-loop ones and are thus relevant for phenomenology. (ii) Although not unique, a rare feature -- which we refer to as apparent non-decoupling -- emerges in the light effective theory. The renormalizable ALP interactions fail to capture this behavior and therefore are incomplete as low-energy effective descriptions.

    hep-phPoS(2026)·0 citations
14. 14*

    Towards six W-boson amplitude at two loops

    A.V. Belitsky🇺🇸

    We construct the planar integrand of the six-leg amplitude of massive W-bosons on the special Coulomb branch of the maximally supersymmetric Yang-Mills theory to two-loop order. We use the six-dimensional supersymmetric spinor-helicity formalism and the generalized unitarity-cut sewing technique to perform this analysis. The thus-found expression corresponds in the massless limit to the six-gluon maximally helicity-violating amplitude. The upshot of the current consideration is that the former is just an uplift of the latter from four to six dimensions. This repeats the pattern found earlier for four- and five-leg amplitudes of massive W-bosons.

    ↳ hep-thhep-ph5 citations
15. 15*

    Is there a retrograde accretion disk around 4U 1626$-$67? Tracking torque reversals with a state-space model

    Joseph O'Leary🇦🇺 · Andrew Melatos🇦🇺 · Tom Kimpson🇦🇺 · Dimitris M. Christodoulou🇺🇸 · Nicholas J. O'Neill🇦🇺 · Patrick M. Meyers🇺🇸 · Sayantan Bhattacharya🇺🇸 · Silas G.T. Laycock🇺🇸

    X-ray timing studies of the persistent, Galactic, accretion-powered pulsar 4U 1626$-$67 reveal torque reversals, during which the pulse frequency $\nu (t)$ alternates between multiyear episodes of secular acceleration and deceleration, separated by transitions lasting $\lesssim 150\mathrm{days}$. Here an unscented Kalman filter is applied to track the $\nu (t)$ fluctuations observed in 22.7 years (3340 samples) of publicly available Compton Gamma-Ray Observatory and Fermi Gamma-Ray Space Telescope data to test the canonical picture of magnetocentrifugal accretion for consistency with prograde-prograde and retrograde-prograde accretion disk configurations on either side of the 2008 torque reversal. It is found that the retrograde-prograde model is preferred, with a log Bayes factor equal to 0.44 and maximum a posteriori log likelihood ratio equal to 2.5. The mass accretion rate $Q(t)$ and magnetocentrifugal fastness $\omega (t)$ transition smoothly between episodes of deceleration and acceleration; $Q(t)$ shifts by $\le 0.34\mathrm{dex}$ across the reversal, and one measures $\omega (t)\approx 0.25$ and $\omega (t)\approx 0.30$ during deceleration and acceleration, respectively. The angular acceleration $\dot{\Omega }(t)$ satisfies $-9\lesssim \dot{\Omega }(t)/(10^{-12}\mathrm{rad}{\mathrm{s}}^{-2})\lesssim -5$ and $2\lesssim \dot{\Omega }(t)/(10^{-12}\mathrm{rad}{\mathrm{s}}^{-2})\lesssim 9$ before and after the 2008 reversal, respectively, compared to $\dot{\Omega }\approx -3.0\times 10^{-12}\mathrm{rad}{\mathrm{s}}^{-2}$ before reversal and $\dot{\Omega }\approx 2.5\times 10^{-12}\mathrm{rad}{\mathrm{s}}^{-2}$ after reversal, as inferred from previous long-term X-ray timing and spectral analysis of 4U 1626$-$67.

    ↳ astro-ph.HEhep-phApJ(2026)·1 citation
16. 16*

    Oscillations of dark matter halos in galaxies and their effects on motion of stars

    V. V. Flambaum🇦🇺 · I. B. Samsonov🇦🇺

    Matter and dark matter in galaxies represent two main components linked by the gravitational interaction. Collisions of galaxies may create an offset between the centers of mass of these components. Ignoring internal dynamics of particles in the dark matter halo and Keplerian rotations of matter in the galaxy, we focus on possible relative oscillations of the matter in the dark matter halo. This two-fluid model is somewhat similar to the ``giant dipole resonances'' in nuclei. We estimate possible amplitude and frequency of such oscillations assuming that the offset of the centers of mass is small as compared with the size of the galaxy. Such oscillations, if exist, should manifest themselves in anomalies of velocities of stars in the galaxy, such as the density waves and runaway stars which have orbit periods in resonance with oscillations.

    ↳ astro-ph.GAastro-ph.COhep-phMNRAS(2026)·0 citations
17. 17*

    The phases of QCD reached in terrestrial and cosmic colliders

    Sourendu Gupta🇮🇳

    We review the current state of knowledge of the phase diagram of QCD through lattice, effective field theories, and chiral models. Several sections through the three dimensional phase diagram are known for $N_f=2+1$ with good precision. Due to technical advances in lattice techniques over the last decade or so, new aspects of the phase diagram can now be explored. We review current lattice results. The newly acquired knowledge can be used to reconstruct the full phase diagram for physical QCD, \ie, $N_f=1+1+1$. We remark on the computations which would help understand this better, and what the current constraints are on matter in neutron star cores. We also remark on the physics of the chiral transition and neutron stars in the 't Hooft large $N_c$ limit.

    ↳ hep-latastro-ph.HEhep-phnucl-th0 citations
18. 18*

    Deuteron yields near the QCD phase transition

    Sheng-nan Han🇨🇳 · Jing Wu🇨🇳 · Yong-rui Chen🇩🇪 · Yi-zhen Huang🇨🇳 · Feng Li🇨🇳 · Wei-jie Fu🇨🇳

    We investigate the influence of QCD phase transition and critical fluctuations of the critical end point (CEP) on the deuteron yield within the functional renormalization group (fRG) approach, by using the nucleon coalescence model and a low energy effective field theory of quarks and mesons. It is found that the two-point baryon density correlation function is enhanced in a narrow region radiated from the CEP along the phase boundary. The deuteron yield arising from the two-point baryon correlation is small compared to the leading-order contribution, which is attributed to the fact that in the regime of low collision energy, i.e., the region of large baryon chemical potential, the freeze-out curves deviate from the critical region, resulting in that the enhancement of the deuteron yield stemming from the critical fluctuations near the CEP is mild.

    ↳ nucl-thhep-phPRD(2026)·1 citation
19. 19*

    A Bottom-Up EFT Approach To Superdense Baryonic Matter

    Mannque Rho🇫🇷

    How to arrive at the densest matter in massive compact stars starting from Walecka's linear $\omega$-$\sigma$ mean-field model is described in a series of arguments anchored on hidden local symmetry, hidden scale symmetry and emergent parity-doublet symmetry. I follow the bottom-up approach from chiral symmetry with pions, coupled to hidden local and scale symmetry degrees of freedom. Exploiting the renormalization-group treatment à la Shankar and Polchinski of the fermionic interactions on the Fermi sphere, leading to Landau-Migdal Fermi-liquid, one obtains a sort of generalized ``Density Functional" that allows via a topology change hadrons transform to quarks without phase changes at the center of massive stars. The highly dense matter is ``pseudo-conformal" with the sound velocity $v_{pcs}^2/c^2\approx 1/3$ but the trace of the energy-momentum tensor is not equal to zero, hence the matter is non-conformal.

    ↳ nucl-thastro-ph.HEastro-ph.SRhep-ph1 citation
20. 20*

    Weak gravity at micron scales from dark bubble cosmology and its cosmological consequences

    Ulf Danielsson🇸🇪 · Suvendu Giri🇸🇪

    The dark bubble model makes a positive cosmological constant natural in string theory, and predicts several new physical phenomena within reach in the near future. In this paper we study the experimental consequences of the model for the strength of gravity at scales of order $10^{-5}$m. Contrary to other models of gravity involving extra dimensions, the dark bubble model predicts gravity to become weaker rather than stronger at small scales, compared to Newtonian gravity. In particular, we provide explicit predictions of measurable deviations using table top experiments. We also show how the same effect reduces the effective force of gravity at high energy densities in cosmology, leading to a period of early inflation without the need for anything beyond radiation. We also discuss the quantum origin of the universe with a 5D black hole acting as a catalyst for the nucleation of the dark bubble and how it accounts for the present matter content in the universe. This leads to a prediction of ${\Omega }_c\approx 5\times 10^{-4}$ for a positive curvature of the universe, suggesting an explanation of the why-now-problem of the cosmological constant. We end by speculating on how to incorporate AdS black shells as black hole mimickers within the dark bubble model.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2026)·2 citations
21. 21*

    Friction in Stochastic Inflation

    Baptiste Blachier🇧🇪 · Christophe Ringeval🇧🇪

    We solve time-reversed stochastic inflation in the semi-infinite flat potential with a constant drift term and derive an exact expression for the probability distribution of the curvature fluctuations. It exhibits exponential decaying tails which contrast to the Levy-like power law behaviour encountered without friction. Such a non-vanishing drift acts as a regulator for the conventional ``forward'' stochastic $\delta N$-formalism, which is otherwise ill-defined in the unbounded and flat potentials typical of plateau models of inflation. This setup therefore allows us to compare the curvature distribution derived from both approaches, reverse and forward in time. Up to similar exponential tails, we find quantitative differences. In particular, in the classical-like limit of very large drift, the tails become Gaussian but only in the time-reversed picture. As a toy model of eternal inflation, we finally discuss the case of negative drift in which inflation never ends for many field trajectories. The forward approach becomes pathological whereas the reverse formalism gives back a finite curvature distribution with always exponential tails. All these differences end up being related to the very definition of the background which is ambiguous when a classical trajectory does not exist.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2026)·5 citations
22. 22*

    Notes on Fourier transform and its application to three-point momentum-space integrals

    Xuhang Jiang🇨🇳

    The Fourier transform of two-point momentum-space Feynman integrals with massless propagators and two off-shell legs can be used to prove identities between their periods, exemplified by the glue-and-cut identity. We generalize this framework to massless momentum-space Feynman integrals with three off-shell legs and obtain a similar family of identities that can be used to calculate these integrals, especially for a non-planar subset of them, which naturally arise in the off-shell Sudakov form factors.

    ↳ hep-thhep-phPRD(2026)·2 citations
23. 23*

    Gauge theories from scattering amplitudes with minimal assumptions

    Renato M. Fonseca🇪🇸 · Clara Hernandez-Garcia🇪🇸 · Javier M. Lizana🇪🇸 · Manuel Perez-Victoria🇪🇸

    We revisit the emergence of a Yang-Mills symmetry in theories with massless spin 1 particles from fundamental physical properties of scattering amplitudes. In the standard proofs, some symmetry and reality properties of the coupling constants in three-point amplitudes are assumed. These properties cannot be justified using only three-point amplitudes but we show that they arise as consequences of the consistent factorization of four-particle amplitudes, for particular choices of the particle basis. This applies to self-interactions of massless spin 1 particles and also to their interactions with spin 0 and 1/2 particles. CP invariance is a derived property, not an additional assumption. The situation for gravity interactions is analogous and it is dealt with in the same fashion.

    ↳ hep-thhep-phJHEP(2026)·4 citations
24. 24*

    Axion Constraints from White Dwarf Cooling in 47 Tucanae

    Leesa Fleury🇨🇦 · Alysa Obertas🇨🇦 · Harvey Richer🇨🇦 · Jeremy Heyl🇨🇦

    We analyse the cooling of white dwarfs in the globular cluster 47 Tucanae to look for evidence of axion emission affecting the rate of white dwarf cooling. If axions exist and couple to electrons, then axions could be produced at an appreciable rate in the electron-degenerate core of a white dwarf through axion bremsstrahlung from electrons. The emission of these axions would provide an additional cooling mechanism for white dwarfs that would affect the cooling rate, and hints of axions have been suggested based on observations of anomalous cooling reported for white dwarfs in the Galactic disc and halo. We performed stellar evolution simulations of white dwarf cooling that accounted for the additional energy loss due to axion bremsstrahlung from electrons, producing a suite of white dwarf cooling models for different values of the axion-electron coupling constant, as well as the white dwarf mass and envelope thickness. These cooling models are compared to observations of white dwarfs in 47 Tucanae from the Hubble Space Telescope through an unbinned likelihood analysis. The optimal model found by this analysis corresponds to the case of no axion emission with a thick white dwarf envelope, and we find a new bound on the axion-electron coupling of $g_{aee}\le 0.81\times 10^{-13}$ at 95% confidence level, conditional on the adopted white dwarf cooling models and priors. This bound improves upon the previous white dwarf cooling bound for this coupling and excludes the range of values favoured by the axion hints from the anomalous cooling of Galactic white dwarfs.

    ↳ astro-ph.SRastro-ph.GAhep-ph7 citations
25. 25*

    Probing Exotic Astrophysical Dark objects through Astrometric Microlensing from Gaia

    Lalit Singh Bhandari🇮🇳 · Vikram Rentala🇮🇳 · Arun M. Thalapillil🇮🇳 · Himanshu Verma🇺🇸

    We present the first comprehensive study of astrometric microlensing by exotic astrophysical dark objects, focusing on two theoretically motivated models -- Q-ball and boson star. We demonstrate that these extended objects generate distinctive signatures that depart markedly from point-mass lenses like primordial black holes. The smoking-gun signature for these exotic objects is the emergence of caustics, which form when the lens radius is below a critical threshold. Crossing these caustics induces discontinuous jumps in the images-centroid trajectory, a distinctive feature of these extended dark objects. We show these patterns are sensitive to the internal mass profile, with boson stars generating larger, more prominent caustic structures than Q-balls -- enabling the models to be distinguished. Using the Gaia DR3 stellar catalogue, we forecast a high-yield discovery potential, up to $\sim 6000$ detectable astrometric microlensing events for a 10-year mission, peaking for $M\sim 1-10M_{\odot }$ and $R\lesssim 10\text{AU}$. In the absence of anomalous detections, Gaia can set powerful 90% confidence level constraints on the fractional abundance of these exotic objects, reaching $f_{\mathrm{DM}}\le 10^{-3}$ in the peak region which covers masses from $10^{-1}-10^7{M}_{\odot }$ and radii $R<10^6\text{AU}$. Crucially, these projected astrometric microlensing constraints are significantly stronger than existing photometric microlensing limits in the $1-10M_{\odot }$ mass range. This work establishes astrometric microlensing with Gaia as a powerful, complementary, and near-future probe with the potential to discover exotic astrophysical dark objects.

    ↳ astro-ph.GAastro-ph.COgr-qchep-ph2 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.