HEP Phenomenology·hep-ph

Mon·Aug 10, 2026Monday·August 10, 2026

23 papers—13 primary·10 cross-listed

01
Generative Amplification with Surrogate Monte Carlo
Henning Bahl🇩🇪 · Tilman Plehn🇩🇪 · Rebecca Revelli🇩🇪
Amplitude surrogates for LHC simulations build on generative amplification, the fact that a surrogate trained on an expensive and small training dataset describes the smooth amplitude more precisely than the training data does. Applying techniques developed for generative networks, we quantify this amplification for gluon-associated $Z$ production. Significant amplification appears in sparsely populated kinematic tails, where it matters most. Our results show how generative amplification from surrogate Monte Carlo far outperforms the density estimation in current generative networks.
hep-ph1 citation
02
Logarithmic Wavelets for Dark Matter--Phonon Scattering
Xu-Xiang Li🇺🇸 · Zhengkang Zhang🇺🇸
Phonon excitations in crystals are a promising detection channel for sub-GeV dark matter (DM), and anisotropic targets add directional sensitivity through the daily modulation of the rate. Exploiting these capabilities requires evaluating six-dimensional rate integrals across DM models, target materials, detector orientations, and times of day. The vector space integration method factorizes the calculation into projections of the DM velocity distribution and of the material response -- each computed once and reused -- contracted with an analytic kinematic matrix, reducing such scans to fast matrix algebra. In the phonon channel, however, the relevant momentum transfers span six orders of magnitude, and the linearly spaced Haar wavelet basis of existing implementations falls short: light mediator models demand an impractically large basis, and a single projection reused across DM masses loses its effective resolution for light DM. We introduce a logarithmic Haar wavelet basis that resolves both obstacles, and present a package VectorPhonoDark that implements the approach. On an Al $_{2}$ O $_{3}$ daily modulation benchmark, it reproduces results from PhonoDark's direct numerical integration while reducing the computational cost by orders of magnitude. Though developed here for phonons, the logarithmic wavelet basis generalizes to any DM detection channel spanning a wide range of momentum transfers, enabling efficient scans over DM models and detection strategies.
hep-ph0 citations
03
Oscillating Neutrinos vs. Oscillating Scalars: Constraining Scalar Dark Matter-Induced Neutrino Mass
Kierthika Chathirathas🇩🇪 · Sabya Sachi Chatterjee🇩🇪 · Thomas Schwetz🇩🇪
We consider the hypothesis that neutrino masses are generated by a coupling to an ultra-light (pseudo-)scalar field, which provides the dark matter in the universe. This leads to time-varying neutrino masses with a frequency set by the dark matter mass, with implications for neutrino oscillation data. We use that dark matter is in a virialised state in the galaxy and provide a detailed discussion of the relevant time scales. Using data from the T2K, RENO and JUNO experiments, we show that for dark matter masses smaller than about $3 \times 1 0^{- 8}$ eV down to the smallest allowed dark matter mass of about $1 0^{- 21}$ eV only a fraction of between 9\% to 54\% of the total neutrino mass can arise from the coupling to the background scalar, depending on the value of the scalar mass. Future data from JUNO may improve these limits down to 1\% in certain regions of scalar masses. We focus on a real scalar field, but most of our results hold also for a complex scalar.
hep-phhep-ex1 citation
04
Quantum Computers will constrain the Equation of State of Neutron Stars
Adrián Castaño-García · Nahia J. Dios-Bilbao · J. J. Gálvez-Viruet🇪🇸 · Felipe J. Llanes-Estrada🇪🇸 · Marío Logrosán-Álvarez · Nicolás M. Arenaza🇪🇸 · María Gómez-Rocha🇪🇸
The Equation of State (EoS) of Nuclear Matter at high densities, and particularly that of neutron stars, resists $ab$ $initio$ Quantum Chromodynamics (QCD) computations due to the notorious sign problem of Lattice Gauge Theory at finite chemical potential. A quantum computer deploying QCD in canonical quantization should be able to make substantial progress. We set some basic goals for a future quantum computer to predict the EoS, and thus the basic static observables of the star (mass, radius and Tidal deformability, for example). We then develop the basic theory to address the canonical Hamiltonian in Weyl (time-axial) gauge expressed in normal modes, together with the squared Gauss operator $G^{2}$ necessary to execute energy minimization algorithms restricted to the physical Fock subspace. Finally, we deploy our particle-quantum register encoding of a generic field theory to demonstrate QCD at finite chemical potential for a few (three-four) particles with a modest number of momentum modes, by simulating the quantum computer on a classical cluster. This opens the possibility for effective quantum computers to constrain the microscopic physics of neutron stars simultaneously to the operation of third--generation gravitational wave detectors such as the Einstein Telescope, providing more detailed predictions than has been possible until now.
hep-phnucl-thquant-ph0 citations
05
$q q ˉ$ scattering phase shift in the $π^{0}$ channel and $π^{0}$ meson spectral function under external magnetic field and finite meson momentum
Min Zhou🇨🇳 · Zhiyang Liu🇨🇳 · Yvming Tian🇨🇳 · Chonglong Xie🇨🇳 · Guoyun Shao🇨🇳 · Shijun Mao🇨🇳
$q q ˉ$ scattering phase shift in the $π^{0}$ channel $Φ_{π^{0}} (ω^{2}, k_{⊥}^{2}, k_{3}^{2})$ and $π^{0}$ meson spectral function $ρ_{π^{0}} (ω^{2}, k_{⊥}^{2}, k_{3}^{2})$ under external magnetic field $e B$ and finite meson momentum $k_{⊥}^{2}, k_{3}^{2}$ are studied in the framework of a two-flavor Nambu-Jona-Lasinio (NJL) model. The $q q ˉ$ scattering phase shift in the $π^{0}$ channel $Φ_{π^{0}}$ is closely related to $π^{0}$ spectral function $ρ_{π^{0}}$ . We consider three situations, chiral broken phase ( $T = μ = 0$ ), chiral restoration phase ( $T > T_{p c}, μ = 0$ ) and chiral restoration phase ( $T = 0, μ > μ_{p c}$ ). For $T = μ = 0$ and $T > T_{p c}, μ = 0$ cases, $π^{0}$ meson spectral function $ρ_{π^{0}}$ shows a delta peak, several Breit-Wigner peaks and several non-Breit-Wigner peaks. The delta peak indicates the bound state of $π^{0}$ meson, and the Breit-Wigner peak means the resonant state of $π^{0}$ meson. For $T = 0, μ > μ_{p c}$ case, Pauli blocking effect plays a role, which changes the inner structure of these Breit-Wigner peaks and non-Breit-Wigner peaks. Such multiple peak structure is caused by the external magnetic field. The $q q ˉ$ scattering phase shift in the $π^{0}$ channel $Φ_{π^{0}}$ shows a jump from $0$ to $π$ when $π^{0}$ meson is in bound state. When $π^{0}$ meson is in resonant state, $Φ_{π^{0}}$ has the value $π /2$ and changes continuously. In large $ω$ region, at the starting and end points of wide peaks of spectral function, $Φ_{π^{0}}$ jumps abruptly (from $π$ to finite value or from finite value to $0$ ), and such jumps are caused by the external magnetic field. Finite momentum $k_{⊥}^{2}$ or $k_{3}^{2}$ modifies the spectral function $ρ_{π^{0}}$ and scattering phase shift $Φ_{π^{0}}$ , which demonstrates the anisotropy in the system induced by external magnetic field.
hep-phnucl-th1 citation
06
A Compatibility Check: Low-Scale Chiral $U (1)_{X}$ Theories Vs. $(g - 2)_{e}$ Anomaly
Bibhabasu De🇮🇳
Chiral Abelian extensions of the Standard Model (SM) gauge group may offer significant new possibilities for explaining various Beyond the Standard Model (BSM) phenomena within a common framework. The models being less explored in the literature only a few experimental constraints have been reported to date, leaving a major portion of the parameter space available for the New Physics (NP) phenomenology. The present paper considers three anomaly-free chiral Abelian extensions and examines the compatibility of the corresponding low-scale parameter spaces with the observed $(g - 2)_{e}$ anomaly. The analysis results in stringent exclusion limits, completely ruling out the considered chiral models when used in complementarity with the existing experimental bounds.
hep-ph0 citations
07
Probing dark matter through charged Higgs pair production at future multi-TeV muon colliders: A machine-learning analysis
Khiem Hong Phan🇩🇰 · Quang Hoang-Minh Pham🇻🇳
Probing dark matter (DM) via charged Higgs pair production at future multi-TeV muon colliders is investigated within the Inert Doublet Model (IDM). The viable parameter space of the IDM is first updated by incorporating theoretical constraints and current experimental data. Based on the allowed parameter space, we evaluate DM relic density and compare the results with the latest constraints from direct DM detection experiments. The resulting parameter points consistent with all DM constraints are subsequently employed to study charged Higgs pair production at future multi-TeV muon colliders, including the subsequent decays of the charged Higgs bosons into Standard Model (SM) particles in association with DM candidate. In particular, we study the following production processes: $μ^{-} μ^{+} \to ν_{μ} ν ˉ_{μ} H^{\pm} H^{\mp} \to ℓ^{+} ℓ^{-} + ν_{μ} ν ˉ_{μ} ν_{ℓ} ν ˉ_{ℓ} H H$ , $μ^{-} μ^{+} \to ν_{μ} ν ˉ_{μ} H^{\pm} H^{\mp} \to ℓ^{\pm} + 2 jets + ν_{μ} ν ˉ_{μ} ν_{ℓ} H H$ and $μ^{-} μ^{+} \to ν_{μ} ν ˉ_{μ} H^{\pm} H^{\mp} \to 4 jets + ν_{μ} ν ˉ_{μ} H H$ for $ℓ = e, μ$ . The signal significance is evaluated against the corresponding SM backgrounds using both cut-based and machine-learning (ML) approaches. We find that ML framework substantially enhances the sensitivity to the signal processes compared with the conventional cut-based analysis. Furthermore, our results indicate that the DM signals through charged Higgs pair production can be indirectly probed with a statistical significance exceeding $5 σ$ for several viable benchmark points at future multi-TeV muon colliders.
hep-ph0 citations
08
Leptogenesis via Resonant Sequential Dominance and TBC3 Mixing in a Type-I Seesaw Model
Michael Fodroci🇯🇵 · Teruyuki Kitabayashi🇯🇵
We demonstrate how phenomenological model construction assuming Sequential Dominance can be extended to cases with degenerate right-handed neutrino masses. Because this framework accommodates resonant leptogenesis, we designate it as Resonant Sequential Dominance. We then investigate Dirac mass matrix textures compatible with current neutrino data within Resonant Sequential Dominance, utilizing a novel neutrino mixing matrix ansatz termed TBC3, proposed in this work. Additionally, we present an $A_{4} \times (Z_{3})^{4} \times (Z_{2})^{2}$ -symmetric Lagrangian that is consistent with neutrino oscillation data and successfully drives resonant leptogenesis. Lastly, we find that accounting for the observed baryon asymmetry of the Universe requires the lightest right-handed neutrino mass to lie in the range $0.13 TeV \leq m_{N_{1}} \leq 230 TeV$ .
hep-ph0 citations
09
Extraction of Pion Unpolarized Quark and Gluon Generalized Parton Distributions using Deep Neural-Networks
Satyajit Puhan🇹🇼 · Shubham Sharma🇷🇺 · Narinder Kumar🇮🇳
We present a deep neural-network (DNN) extraction of the pion unpolarized quark and gluon generalized parton distributions (GPDs) using the corresponding parton distribution functions (PDFs) from the JAM21 and xFitter analysis, together with experimental measurements of the pion electromagnetic form factor (EMFF) and lattice quantum chromodynamics (QCD) results. The GPDs are parameterized using a physics-informed neural-network (PINN) that incorporates the known PDF behavior, an exponential momentum-transfer dependence, and a trainable neural network (NN) component. The network parameters are determined by minimizing a $χ^{2}$ -based loss function. For the valence-quark GPDs, the loss function includes contributions from the EMFF, squared EMFF, charge-normalization constraints, and regularization terms. For the gluon GPDs, it incorporates constraints from the gluon gravitational form factors together with regularization. This framework enables a flexible, nonparametric extraction while preserving the essential theoretical and phenomenological constraints. By employing the full ensemble of available PDF replicas, we quantify the uncertainties of the extracted GPDs over a broad kinematic range in the longitudinal momentum fraction and momentum transfer, with the uncertainty bands corresponding to the $1 σ$ confidence interval. The extracted valence-quark GPDs are found to be in good agreement with available lattice-QCD calculations. Our study demonstrates that DNN-based methods provide a flexible and robust framework for extracting pion GPDs and probing the multidimensional internal structure of the pion, offering a promising avenue for future investigations of hadron tomography.
hep-ph0 citations
10
Axion Dark Matter Modulated Spin Wave Interferometry
Jiayi Liu🇨🇳 · Chen-Hui Xie🇨🇳 · Runyu Lei🇨🇳 · Sichun Sun🇨🇳 · Yu Gao🇨🇳 · Jinxing Zhang🇨🇳
We propose a novel asymmetric spin wave interferometer to detect ultralight axion dark matter. The axion modulates spin-wave properties via a weak effective magnetic field in ferromagnets. The interferometer splits a spin-wave source into two paths of different lengths and sets them to interfere destructively. The system then converts the axion-induced phase shift into a measurable magnetization oscillation that can radiate electromagnetic waves and generate electrical signals via Faraday induction. The signal-to-noise ratios have been evaluated for three detection schemes: the linear amplifier, the single-photon detector, and the electrical signal detection approach, accounting for both magnetization fluctuation and thermal noise. The accessible axion mass range is approximately $1 0^{- 8}$ eV to $1 0^{- 6}$ eV, set by the spin wave propagation length and the relaxation time.
hep-phhep-ex0 citations
11
Enlightening dark moments of neutrino with superradiance
Indra Kumar Banerjee🇮🇳 · Ujjal Kumar Dey🇮🇳 · Anna John🇮🇳
Neutrinos can acquire electromagnetic moments either within the Standard Model through higher order radiative corrections or within the domain of new physics. In this study we focus on probing these beyond the standard model neutrino moments through quenched superradiance of black holes where fermionic pairs can be produced from the superradiant bosonic cloud. We consider the production of dark photons from black hole superradiance and quenching occurs through the production of neutrino-antineutrino pairs from the dark photons. The efficiency of the pair production depends on the effective coupling between the dark photons and neutrinos, i.e., the dark electromagnetic moments. We also discuss bounds on primordial black hole abundance from neutrino background arising from this quenched superradiance mechanism.
hep-phastro-ph.HEgr-qc0 citations
12
Chiral Doubling of Heavy-Light Hadrons and the New Beauty--Strange $B_{s 0}^{*} (5700)^{0}$ Candidate
Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸
The recent observation by the LHCb Collaboration of a new beauty--strange meson $B_{s 0}^{*} (5700)^{0}$ ~\cite{LHCb:2026Bs0star}, under the conditional assignment $J^{P} = 0^{+}$ provides an important new test of the chiral organization of heavy-light hadrons. More than three decades ago it was proposed that the coexistence of heavy-quark spin symmetry and spontaneously broken chiral symmetry implies that every heavy-light spin multiplet should possess an opposite-parity partner separated by a nearly universal mass gap determined primarily by the dynamics of the light degrees of freedom~\cite{Nowak:1993vc,Bardeen:1993ae}. This chiral doubling scenario was later developed into a quantitative heavy-hadron effective theory and extended to the complete charm and beauty spectra. In particular, the strange beauty sector was predicted to exhibit a parity splitting closely related to that of the strange charm sector, with only small $1/ m_{Q}$ corrections. We briefly review the symmetry origin of chiral doubling, derive the universal parity splitting through the heavy-hadron chiral effective theory, and discuss the new LHCb observation in the context of the original theoretical predictions. Taken together with the established charm spectrum, if the new beauty-strange state is confirmed to have $J^{P} = 0^{+}$ , its mass is consistent with its interpretation as the chiral partner of the ground state $B_{s}^{0}$ . Finally, we stress that the above confirmation of the spin and parity imposes in the chiral doubling scenario an existence of yet unobserved, very narrow beauty-strange meson with assignment $1^{+}$ at 5747 $\pm$ 2 MeV. This work is dedicated to the memory of our friend and collaborator Mannque Rho (1936--2026).
hep-phhep-exhep-thnucl-th0 citations
13
Optimal Calibration-Free Observable for the Nucleon-Coupling Ratio in a Dual-Alkali Comagnetometer for Dark Matter Searches
Yossi Rosenzweig🇮🇱 · Yevgeny Kats🇮🇱 · Eli Sarid🇮🇱 · Menachem Givon🇮🇱 · Yonathan Japha🇮🇱 · Ron Folman🇮🇱
A dual-alkali single-cell $^{87}$ Rb- $^{39}$ K- $^{3}$ He comagnetometer can read an axionlike dark matter signal through two optical-rotation channels, encoding the ratio $R = ξ_{n} / ξ_{p}$ of the field's neutron and proton spin couplings in their relative response. The inter-species phase difference $Δ φ$ has been proposed as a calibration-free readout that is sensitive to $R$ . Treating the extraction of $R$ as a statistical estimation problem, we show that the optimal observable is the complex inter-channel ratio, which splits into $Δ φ$ and an amplitude ratio, of which only $Δ φ$ is insensitive to the relative gain and hence calibration-free. For our choice of comagnetometer parameters, above $\sim 100$ Hz the phase difference alone captures most of the coupling-ratio information. At lower frequencies $Δ φ$ is not near-sufficient: there the amplitude ratio would improve the precision on $R$ by a factor of $≳ 2$ below $\sim 40$ Hz. Recovering that information, however, requires the relative gain to be known sufficiently accurately, so $Δ φ$ stays the robust observable even where it is not the optimal one.
hep-phphysics.atom-ph0 citations
14
Reconstructability and directed flow of short-lived resonances in Au+Au collisions at 19.6 and 200 GeV
Junyi Han🇨🇳 · Xialei Jiang🇨🇳 · Hongcan Li🇨🇳 · Yaping Wang🇨🇳
We present a systematic study of the reconstructability and directed flow of hadronic resonances in Au+Au collisions within the UrQMD transport model. The main objective of this work is to investigate how the hadronic stage influences both resonance reconstructability and the final-state directed flow. A set of short-lived hadronic resonances, including $ρ^{0}$ , $K^{* 0}$ , and $Λ (1520)$ , is investigated to quantify their yields and reconstructable fractions as a function of charged-particle multiplicity, characterized by $(d N_{c h} / d η)^{1/3}$ . We compare results at $s_{N N} = 19.6$ and $200 GeV$ to investigate possible energy-dependent differences in the reconstructability. Such differences reflect variations in the properties of the hadronic medium. The results are further examined as a function of resonance lifetime, revealing a clear ordering of reconstructability among different resonances. Overall, the reconstructability is found to be primarily governed by resonance lifetime. The directed-flow analysis reveals clear differences between resonances and their corresponding stable hadrons in mid-central collisions, while these differences become significantly weaker in peripheral collisions, highlighting the important role of hadronic evolution in shaping the final-state directed flow. These studies provide a unified picture of how the hadronic stage influences both resonance reconstructability and directed flow, offering new insights into resonance observables in relativistic heavy-ion collisions.
↳ nucl-thhep-phnucl-ex0 citations
15
Quasi-steady flavor configuration of multi-energy neutrino ensembles
Manuel Goimil-García🇩🇰 · Irene Tamborra🇩🇰
Neutrino flavor conversion profoundly impacts the explosion mechanism and multi-messenger emissions of core-collapse supernovae. Yet, state-of-the-art hydrodynamic simulations of neutrino-dense astrophysical environments cannot account for neutrino quantum kinetics, necessitating subgrid schemes to model the impact of neutrino self-interaction on the quasi-steady-state flavor configuration. We present semi-analytical approximations for the outcomes of both slow and fast flavor conversions in quasi-homogeneous systems with periodic boundary conditions. Independent of the mass ordering, our ansatz demonstrates excellent agreement with multi-angle and multi-energy solutions of the neutrino kinetic equations across a wide range of representative (anti)neutrino distributions.
↳ astro-ph.HEhep-ph1 citation
16
Cosmic birefringence from a joint analysis of ACT and Planck
Johannes R. Eskilt🇳🇴
Dark matter and dark energy could be ultra-light pseudoscalar fields that couple to electromagnetism through a Chern-Simons term. This would cause a parity-breaking rotation of the plane of linearly polarized light from the cosmic microwave background, known as cosmic birefringence, which is not predicted by $Λ$ CDM. Recent hints of a non-zero cosmic birefringence angle have been found in both the Planck Data Release 4 and ACT Data Release 6 datasets independently. This work jointly analyzes the polarized maps of both, leveraging the cross-power spectra between the two telescopes. Taking the reported instrumental priors at face value, the joint analysis yields $β = 0.27 7^{\circ} \pm 0.05 7^{\circ}$ , which is non-zero with a statistical significance of $4.8 σ$ . A robustness test mitigating contamination from dust emission excludes $β = 0^{\circ}$ at $3.5 σ$ , and retrieving $β = 0^{\circ}$ would require both the dust $E B$ modeling and instrumental priors to fail simultaneously. However, unresolved systematics in the data must be understood before we can draw strong cosmological conclusions.
↳ astro-ph.COgr-qchep-phhep-thPRD(2026)·1 citation
17
Estimating the sensitivity of the IceCube Upgrade to probe the interior of the Earth using atmospheric neutrino oscillations
The IceCube Collaboration: R. Abbasi🇺🇸 · M. Ackermann🇩🇪 · J. Adams🇳🇿 · S. K. Agarwalla🇮🇳 · J. A. Aguilar🇧🇪 · M. Ahlers🇩🇰 · J.M. Alameddine🇩🇪 · S. Ali🇺🇸 · N. M. Amin🇺🇸 · K. Andeen🇺🇸 · C. Argüelles🇺🇸 · S. Athanasiadou🇩🇪 and 411 other authors
The IceCube Upgrade is a densely instrumented central region of the IceCube Neutrino Observatory, deployed during the 2025-26 polar season. It will reduce the detector's energy threshold and improve overall reconstruction capabilities for multi-GeV atmospheric neutrinos, which in turn enhance their sensitivity to Earth matter effects as they traverse through the deep Earth. In this study, we describe the potential of the IceCube Upgrade to observe Earth matter effects on atmospheric neutrinos and estimate the detector's sensitivity to probe key features of the Preliminary Reference Earth Model by utilizing these observations. We highlight the IceCube Upgrade's capability to estimate the mass of the Earth and verify the non-homogeneous distribution of matter density within the Earth. We also estimate the IceCube Upgrade sensitivity to measure the correlated densities of the Earth layers while incorporating constraints from the mass and moment of inertia of the Earth. Neutrino-based results would be independent and complementary to the seismic and gravitational measurements.
↳ hep-exastro-ph.EPhep-phphysics.geo-ph1 citation
18
Laboratory-frame $T$ -matrix and heavy quark drag in the quark-gluon plasma
Anurag Tiwari🇨🇳 · Min He🇨🇳
Non-perturbative scattering $T$ -matrix is a core input for the evaluation of transport phenomena in a strongly-coupled medium. Existing in-medium $T$ -matrix calculations are typically formulated in the two-particle center-of-mass frame, where the scattering equation can be reduced to a lower-dimensional problem. However, a medium explicitly breaks Lorentz invariance and defines a preferred reference frame, entailing that physical observables be constructed from scattering amplitudes evaluated in the medium rest (laboratory) frame. In this work, by exploiting the rotational symmetry about the scattering-pair-momentum axis, we develop a practical framework for solving the in-medium two-body $T$ -matrix directly in the laboratory frame while retaining the full dependence on the total pair-momentum and scattering geometry. We demonstrate that the resulting amplitudes differ significantly from conventional center-of-mass-frame results and, when applied to heavy-light quark scattering in the quark-gluon plasma (QGP), lead to 25-40% corrections to heavy-quark drag coefficients at low momenta, thereby removing a significant source of theoretical uncertainty in extracting the QGP transport properties with heavy-quark probes.
↳ nucl-thhep-phnucl-ex0 citations
19
Magnetic Catalysis and Fermion Mass Generation in de Sitter Spacetime
Kohei Fujikura🇯🇵 · Toshifumi Noumi🇯🇵 · Shintetsu Yamazaki🇯🇵
We consider the dynamics of a charged fermion in de Sitter space in the presence of a uniform background magnetic field, and discuss magnetic catalysis of chiral symmetry breaking using the Nambu--Jona-Lasinio (NJL) model. We evaluate the mode functions of the charged fermion field in this background by imposing the Bunch--Davies vacuum condition. The gap equation is solved in the mean-field approximation. We derive analytic expressions for the gap in several limiting regimes, such as the large-magnetic-field and large-curvature limits. We find that the curvature effect restores chiral symmetry, whereas the magnetic field enhances chiral symmetry breaking through the conventional mechanism of magnetic catalysis. The phase structure associated with chiral symmetry breaking is revealed by numerical calculations.
↳ hep-thastro-ph.COgr-qchep-ph0 citations
20
Critical dynamics of a scalar field near four spatial dimensions
Laura Batini🇨🇭 · Eduardo Grossi🇮🇹
The critical dynamics of a non-conserved order parameter is generally expected to become overdamped at long distances, even when propagating modes occur at microscopic or intermediate scales. We investigate the critical dynamics of a scalar field theory in thermal equilibrium which, in addition to local friction and noise, also contains a time-dependent second-order kinetic term. We show how to build a supersymmetric field-theory formulation. Using a two-loop expansion about four spatial dimensions, we show that the propagating and strictly overdamped limits share the same static Gaussian and Wilson-Fisher fixed points but realize distinct dynamical scaling regimes. The overdamped limit reproduces Model A. On the surface where local friction and noise vanish, the theory instead supports an interacting propagating fixed point whose dynamic exponent receives corrections at two loops. We demonstrate that coarse-graining does not generate a local dissipative operator on this surface, which therefore remains invariant under the RG flow. Local dissipation is nevertheless relevant at the propagating fixed point: an arbitrarily small equilibrium friction-noise perturbation drives the flow away from propagating scaling. Propagating critical dynamics thus defines a consistent but fine-tuned regime that is unstable to local equilibrium dissipation.
↳ hep-thcond-mat.stat-mechhep-phnucl-th0 citations
21
Inflation with Nieh-Yan-like terms in metric-affine gravity
Ilaria Andrei🇪🇪 · Christian Dioguardi🇪🇪 · Damianos Iosifidis🇮🇹 · Laur Järv🇪🇪 · Antonio Racioppi🇪🇪 · Margus Saal🇪🇪
We study single-field slow-roll inflation in metric-affine gravity with a scalar field non-minimally coupled to the non-Riemannian Ricci scalar and to the divergences of the torsion and nonmetricity vectors, a structure that generalizes the well-known Nieh-Yan term. By imposing projective coherence of the matter sector and solving the connection field equations, we integrate out torsion and nonmetricity and obtain an equivalent Einstein-frame formulation in which the metric-affine couplings are encoded in a modified kinetic function and potential. For the choice of coupling functions $A (ϕ) = M_{P}^{2} + ξ ϕ^{2}$ to the non-Riemannian Ricci scalar, $C_{i} (ϕ) = ξ_{i} ϕ$ to the Nieh-Yan-like terms and a monomial Jordan-frame potential $V \propto ϕ^{k}$ , we show that in the limit of a large positive effective Nieh-Yan-like coupling $ξ ˉ$ the canonical field satisfies $χ \sim ϕ^{2}$ , the Jordan-frame field values during inflation become sub-Planckian, and the Einstein-frame potential reduces to $U \sim χ^{k /2}$ . We compute the slow-roll predictions numerically for quartic and quadratic Jordan-frame potentials and compare them with the current CMB constraints from Planck, BICEP/Keck, ACT, and SPT. We find that intermediate values of $ξ ˉ$ can restore the compatibility of non-minimally coupled Palatini inflation with observations: in the quartic case, the model predicts a tensor-to-scalar ratio within reach of next-generation CMB experiments for $ξ ˉ ≲ 1 0^{4}$ , while in the quadratic case the coupling cures the $η$ -problem arising for $ξ ≳ 1 0^{- 2}$ and yields viable predictions for $1 0^{- 2} ≲ ξ ˉ ≲ 1 0^{2}$ . In the negative $ξ ˉ$ regime, the model does not improve upon standard Palatini inflation, though it can still produce distinct, testable predictions.
↳ gr-qcastro-ph.COhep-ph1 citation
22
Sensitivity of Next-Generation CMB Surveys to Neutrinos and Other Light Relics
Cynthia Trendafilova🇺🇸 · Srinivasan Raghunathan🇺🇸 · Benjamin Wallisch🇸🇪 · Joel Meyers🇺🇸 · Kevork N. Abazajian🇺🇸 · Edoardo Altamura🇬🇧 · Carlo Baccigalupi🇮🇹 · Kimberly K. Boddy🇺🇸 · Thejs Brinckmann🇩🇰 · Yuji Chinone🇯🇵 · Gabriele Coppi🇮🇹 · Francis-Yan Cyr-Racine🇺🇸 and 24 other authors
Neutrinos and other light relics leave characteristic imprints in the cosmic microwave background anisotropies, making their observation a sensitive probe of the particle content and thermal history of the early universe. The energy density in these relativistic species is parameterized by their effective number $N_{eff}$ . Measuring this parameter at the percent level, which is a long-standing science goal of CMB-S4 and other experiments, would test a wide range of well-motivated physics within and beyond the Standard Model of particle physics. In this paper, we present Fisher-matrix forecasts of the projected sensitivity to $N_{eff}$ of several CMB-S4 survey configurations considered during its extensive design phase. The conceptual design reaches $σ (N_{eff}) < 0.03$ over its seven-year observing period, while the revised configuration achieves the same precision over a longer timescale. We complement these results with a cosmic-variance-limited survey over the same multipole range to quantify the room for improvement accessible with additional instrumental, observational, and theoretical efforts. Finally, we discuss the broad implications of precise $N_{eff}$ measurements for the radiation sector, big bang nucleosynthesis, light thermal relics, and other early-universe physics. The forecasts presented in this work are performed with the publicly released DRAFT (Dark Radiation Anisotropy Flowdown Team) tool. It provides an end-to-end pipeline from simulated foreground maps and component separation to delensing and projected sensitivities for any cosmological parameter, and it can be directly applied to other cosmic microwave background survey designs.
↳ astro-ph.COastro-ph.IMhep-phhep-th1 citation
23
Quantum de Sitter and Analytically Continued Chern Simons Theory
Stephon Alexander🇺🇸 · Kenneth Blakey
We give a Lefschetz thimble definition of the Chern--Simons--Kodama wavefunctional in Lorentzian self-dual gravity with positive cosmological constant. By complexifying the connection and choosing the Lefschetz thimble attached to the self-dual de~Sitter saddle, Witten's analytic continuation of Chern--Simons theory replaces the real contour, on which the defining integral is at best conditionally convergent, by an absolutely convergent integration cycle and yields a controlled semiclassical expansion. The relevant integrand is the full holomorphic exponential $e^{I}$ , with $I = κ Y_{CS} + (source)$ , and the steepest descent flow is governed by the Morse function $h = Re I$ . In the homogeneous isotropic de Sitter reduction, the construction reproduces the Hartle--Hawking Airy wavefunction. In the Bianchi~IX truncation, we take the Lefschetz thimble attached to the expanding de~Sitter saddle (the contracting branch defines a conjugate Lefschetz thimble); within this sector, the symmetric configuration is the only critical point for $Λ > 0$ . The corresponding Lefschetz thimble contains one trace direction with the FRW Airy structure and two anisotropic shear directions that are real-Gaussian damped at leading quadratic order. This gives a finite Bianchi~IX wavefunction which, to leading order, is the FRW Airy factor multiplied by a real anisotropy Gaussian. Thus, the Airy behavior is not an artifact of the one-dimensional minisuperspace reduction, but the leading form of the wavefunction on the Lefschetz thimble. We also discuss how the Lefschetz thimble prescription interfaces with Lorentzian reality conditions.
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