A search for a new $Z^{\prime }$ gauge boson predicted by $L_{\mu }-L_{\tau }$ models, based on charged-current Drell–Yan production, $pp\to W^{\pm (*)}\to Z^{\prime }{\mu }^{\pm }\nu \to {\mu }^{\pm }{\mu }^{\mp }{\mu }^{\pm }\nu$, is presented. The data sample used corresponds to an integrated luminosity of $140{\mathrm{fb}}^{-1}$ of proton–proton collisions at $\sqrt{s}=13\mathrm{TeV}$ recorded by the ATLAS detector at the Large Hadron Collider. The search examines a final state of $3\mu$ plus large missing transverse momentum. Upper limits are set on the $Z^{\prime }$ production cross section times branching ratio in the mass range of 5–81 GeV. After combining with the previous $Z^{\prime }$ search using the neutral-current Drell–Yan production with a $4\mu$ final state, the most stringent exclusion limits to date are achieved in the parameter space of the $Z^{\prime }$ coupling strength and mass.

We present a search for an eV-scale sterile neutrino using 7.5 years of data from the IceCube DeepCore detector. The analysis uses a sample of 21,914 events with energies between 5 and 150 GeV to search for sterile neutrinos through atmospheric muon neutrino disappearance. Improvements in event selection and treatment of systematic uncertainties provide greater statistical power compared to previous DeepCore sterile neutrino searches. Our results are compatible with the absence of mixing between active and sterile neutrino states, and we place constraints on the mixing matrix elements $|U_{\mu 4}{|}^2<0.0534$ and $|U_{\tau 4}{|}^2<0.0574$ at 90% CL under the assumption that $\mathrm{\Delta }{m}_{41}^2\ge 1{\mathrm{eV}}^2$. These null results add to the growing tension between anomalous appearance results and constraints from disappearance searches in the $3+1$ sterile neutrino landscape.

We consider the phase shift in the gravitational wave signal induced by fast oscillations of scalar dark matter surrounding binary systems, which could be probed by the future experiments LISA and DECIGO. This effect depends on the local matter density and the mass of the dark matter particle. We compare it to the phase shift due to a standard dynamical friction term, which should generically be present. We find that the effect associated with the oscillations only dominates over the dynamical friction for dark matter masses below ${10}^{-21}\mathrm{eV}$, with masses below ${10}^{-23}\mathrm{eV}$ implying cloud sizes that are too large to be realistic. Moreover, for masses of the order of ${10}^{-21}\mathrm{eV}$, LISA and DECIGO would only detect this effect for dark matter densities greater than that in the solar system by a factor ${10}^5$ or ${10}^4$ respectively. We conclude that this signal can be ignored for most dark matter scenarios unless very dense clouds of very light dark matter are created early in the Universe at a redshift $z\sim {10}^4$.

We derive analytical $\chi \ll 1$ approximations for spin-dependent quantum radiation reaction for locally constant and locally monochromatic fields. We show how to factor out fast spin oscillations and obtain the degree of polarization in the plane orthogonal to the magnetic field from the Frobenius norm of the Mueller matrix. We show that spin effects lead to a transseries in $\chi$, with powers ${\chi }^k$, logarithms $(\ln \chi {)}^k$, and oscillating terms, $\cos (\dots /\chi )$ and $\sin (\dots /\chi )$. In our approach we can obtain each moment, $⟨(kP{)}^m⟩$, of the light-front longitudinal momentum independently of the other moments and without considering the spectrum. We show how to obtain a low-energy expansion of the spectrum from the moments by treating $m$ as a continuous, complex parameter and performing an inverse Mellin transform. We also show how to obtain the spectrum, without making a low-energy approximation, from a handful of moments using the principle of maximum entropy.

The measurements of the lepton flavor universality (LFU) in $\mathcal{B}(\overline{B}\to D^{(*)}l\overline{\nu })$ indicate a significant deviation from the standard model prediction at a $3–4\sigma$ level, revealing a violation of the LFU ($R_{D^{(*)}}$ anomaly). It is known that the $R_{D^{(*)}}$ anomaly can be easily accommodated by an $SU(2{)}_L$-singlet vector leptoquark (LQ) coupled primarily to third-generation fermions, whose existence is further motivated by a partial gauge unification. In general, such a LQ naturally leads to additional $CP$-violating phases in the LQ interactions. In this paper, we point out that the current $R_{D^{(*)}}$ anomaly prefers the $CP$-violating interaction although $\mathcal{B}(\overline{B}\to D^{(*)}l\overline{\nu })$ are $CP$-conserving observables. The $CP$-violating LQ predicts a substantial size of the bottom-quark electric dipole moment (EDM), the chromo-EDM, and also the tau-lepton EDM. Eventually at low energy, the nucleon and electron EDMs are radiatively induced. Therefore, we conclude that the $R_{D^{(*)}}$ anomaly with the $SU(2{)}_L$-singlet vector LQ provides unique predictions: neutron and proton EDMs with opposite signs and a magnitude of $\mathcal{O}({10}^{-27})e\mathrm{cm}$, and suppressed electron EDM. Furthermore, we show that a similar EDM pattern is predicted in an $SU(2{)}_L$-doublet scalar LQ scenario that can accommodate the $R_{D^{(*)}}$ anomaly as well. These EDM signals could serve as crucial indicators in future experiments.

We perform the first lattice calculation on the semileptonic decay of $J/\psi$ using the ($2+1$)-flavor Wilson-clover gauge ensembles generated by CLQCD collaboration. Three gauge ensembles with different lattice spacings, from 0.0519 to 0.1053 fm, and pion masses, $m_{\pi }\sim 300\mathrm{MeV}$, are utilized. After a naive continuum extrapolation using three lattice spacings, we obtain $\mathrm{Br}(J/\psi \to D_{s}e{\nu }_e)=1.90(6)(5{)}_{V_{cs}}\times {10}^{-10}$ and $\mathrm{Br}(J/\psi \to De{\nu }_e)=1.21(6)(9{)}_{V_{cd}}\times {10}^{-11}$, where the first errors are statistical, and the second come from the uncertainties of Cabibbo-Kobayashi-Maskawa matrix element $V_{cs(d)}$. The ratios of the branching fractions between lepton $\mu$ and $e$ are also calculated as $R_{J/\psi }(D_s)=0.97002(8)$ and $R_{J/\psi }(D)=0.97423(15)$ after performing a continuum limit including only $a^2$ term. The ratios provide necessary theoretical support for the future experimental test of lepton flavor universality.

Spectral densities encode nonperturbative information that enters the calculation of a plethora of physical observables in strongly coupled field theories. Phenomenological applications encompass aspects of standard-model hadronic physics, observable at current colliders, as well as correlation functions characterizing new physics proposals, testable in future experiments. By making use of numerical data produced in a $Sp(4)$ lattice gauge theory with matter transforming in an admixture of fundamental and 2-index antisymmetric representations of the gauge group, we perform a systematic study to demonstrate the effectiveness of recent technological progress in the reconstruction of spectral densities.To this purpose, we write and test new software packages that use energy-smeared spectral densities to analyze the mass spectrum of mesons. We assess the effectiveness of different smearing kernels and optimize the smearing parameters to the characteristics of available lattice ensembles. For concreteness, we analyze the $Sp(4)$ lattice gauge theory with matter transforming in an admixture of fundamental and 2-index antisymmetric representations of the gauge group. We generate new ensembles for the theory in consideration, with lattices that have a longer extent in the time direction with respect to the spatial ones. We run our tests on these ensembles, obtaining new results about the spectrum of light mesons and their excitations. We make available our algorithm and software for the extraction of spectral densities, that can be applied to theories with other gauge groups, including the theory of strong interactions (QCD) governing hadronic physics in the standard model.

We present a first practical implementation of a recently proposed hadron structure oriented (HSO) approach to transverse momentum dependent (TMD) phenomenology applied to Drell-Yan-like processes, including lepton pair production at moderate $Q^2$ and $Z^0$ boson production. We compare and contrast general features of our methodology with other common practices and emphasize aspects that we view as improvements. Separately, we discuss the importance of treatments that preserve various theoretical properties of the nonperturbative parts of TMD parametrizations for future applications that have the extraction of hadron structure as a primary goal. These include the HSO’s preservation of a basic TMD parton-model-like framework even while accounting for full TMD factorization and evolution, explicit preservation of the integral relationship between TMD and collinear parton density functions, and the ability to meaningfully compare different theoretical models of nonperturbative TMD parton distributions. In our examples, we show that there is significant sensitivity at moderate $Q^2$ to both the form of the nonperturbative transverse momentum dependence and the parametrization of collinear parton densities. However, we also find that evolving to $Q^2=M_Z^2$, without fitting, results in a satisfactory postdiction of existing data for $Z^0$ production, nearly independently of the modeling of nonperturbative transverse momentum behavior. We argue that this demonstrates that moderate $Q$ measurements should be given greater weight than high $Q$ measurements in extractions of nonperturbative transverse momentum dependence. We also obtain new extractions of the nonperturbative Collins-Soper kernel within the HSO approach. We discuss its features and compare with some earlier extractions.

Neutrino oscillation experiments will be entering the precision era in the next decade with the advent of high statistics experiments like DUNE, HK, and JUNO. Correctly estimating the confidence intervals from data for the oscillation parameters requires very large Monte Carlo datasets involving calculating the oscillation probabilities in matter many, many times. In this paper, we leverage past work to present a new, fast, precise technique for calculating neutrino oscillation probabilities in matter optimized for long-baseline neutrino oscillations in the Earth’s crust including both accelerator and reactor experiments. For ease of use by theorists and experimentalists, we provide fast c++ and fortran codes NuFast.

This paper focuses on the search for a coherent and consistent formulation to describe quantum gravity corrections to quantum field theory. We implement two fundamental ingredients discussed in previous analyses: on one hand, the construction of the Wentzel-Kramer-Brillouin and Born-Oppenheimer picture for the Wheeler-DeWitt theory of gravity and matter by using a reference fluid as physical clock; on the other hand, we explicitly separate in the metric field its own purely classical contribution from the quantum graviton degrees of freedom. This allows to derive, by the expansion in a Planckian parameter, a unitary theory properly evaluating the quantum field theory modifications in the considered regime. More specifically, we recover at zero order the standard theory on curved space-time after averaging over the graviton sector. The physical corrections are induced at first order by (quantum) gravitons, thought as the slow-varying component of the system, as opposed to the fast quantum matter and reference fluid. The genuine contribution due to gravitons, nonfactorizable into an independent phase, provides a coherent quantum gravity modification on quantum field theory. We show this by determining the predicted inflationary spectrum during an exact de Sitter phase of the primordial Universe, finding a breaking of the scale invariant morphology even when the inflation potential is modeled by a cosmological constant term. Remarkably, the behavior of such non-scale-invariant spectrum overlaps predictions previously obtained in literature by neglecting nonunitary terms emerging in those formulations. In this respect, the present model provides a satisfactory regularization of such approaches by virtue of a more realistic construction of the physical clock for the total ($\mathrm{gravity}+\text{matter}$) quantum dynamics.

We point out an interesting connection between the mathematical framework of the Krylov basis, which is used to quantify quantum complexity, and the entanglement entropy in high energy QCD. In particular, we observe that the cascade equation of the dipole model is equivalent to the $SL(2,R)$ Schrödinger equation in the Krylov basis. Consequently, the Krylov complexity corresponds to the average distribution of partons and the Krylov entropy is the counterpart of the entanglement entropy computations of [D. E. Kharzeev and E. M. Levin, Phys. Rev. D 95, 114008 (2017).]. Our work not only brings new tools for exploring quantum information and complexity in QCD, but also gives hope for experimental tests of some of the recent, physical probes of quantum complexity.

A recently proposed pregeometric auxiliary vector mediated gauge theory is studied in its canonical domain, by performing the Legendre transform on a curved background and by considering its covariant phase space, with further application to duality. The constraints become differential equations, but the Dirac-Bergmann algorithm appears consistent with electromagnetic degrees of freedom, metric background permitting. Solving the consistency conditions provides a preferred direction in an intermediary form of spontaneous symmetry breaking. In parallel, the covariant phase space defines the symplectic structure, and establishes the conserved currents and quantum phenomenology with the generated background. The formalism immediately allows one to study the parent path integrals of dual theories, with quartic Proca to Kalb-Ramond inequivalence and Maxwell-Chern-Simons path integral consistency as practical applications, while the differential geometry gives a global description of the issue of Yang-Mills duality rotations. Properties of degenerate metric geometry are discussed throughout, and the viability of inherent backgrounds leads into the fundamental question of background independence in all physical theories.

We compute quasinormal mode frequencies for static limits of physical black holes—semiclassical black hole solutions to Einstein-Hilbert gravity characterized by the finite formation time of an apparent horizon and its weak regularity. These assumptions lead to a highly constrained yet nontrivial form of the metric and components of the energy-momentum tensor near the horizon, which contain as a special case many known models of black holes. Using a two-point M-fraction approximation to construct an interpolating metric which captures the essential near-horizon and asymptotic properties of black holes, we explore a large part of the parameter space that characterizes the near-horizon geometry. We cast the perturbation problem as a discretized homogeneous eigensystem and compute the low-lying quasinormal mode frequencies for perturbations of a massless scalar field. Working in spherical symmetry, we provide rough constraints on leading and subleading deviations from the Schwarzschild solution which arise in a semiclassical setting.

We analytically calculate the spectrum of stochastic gravitational waves (GWs) emitted by expanding string loops on domain walls in the scenario where domain walls decay by nucleation of string loops. By introducing macroscopic parameters characterizing the nucleation of the loops, the stochastic GW spectrum is derived in a way that is independent of the details of particle physics models. In contrast to GWs emitted from bubble collisions of the false vacuum decay, the string loops do radiate GWs even when they are perfectly circular before their collisions, resulting in that more and more contribution to the spectrum comes from the smaller and smaller loops compared to the typical size of the collided loops. Consequently, the spectrum is linearly proportional to the frequency at the high-frequency region, which is peculiar to this GW source. Furthermore, the results are compared with the recent nanohertz pulsar timing array signal, as well as the projected sensitivity curves of future gravitational wave observatories.

Ultrahigh-energy (UHE) cosmic neutrinos, with energies above 100 PeV, could be finally discovered in the near future. Measuring their flavor composition would reveal information about their production and propagation, but new techniques are needed for UHE neutrino telescopes to have the capabilities to do it. We address this by proposing a new way to measure the UHE neutrino flavor composition that does not rely on individual telescopes having flavor-identification capabilities. We manufacture flavor sensitivity from the joint detection by one telescope sensitive to all flavors—the radio array of IceCube-Gen2—and one mostly sensitive to ${\nu }_{\tau }$—GRAND. From this limited flavor sensitivity, predominantly to ${\nu }_{\tau }$, and even under conservative choices of neutrino flux and detector size, we extract important insight. For astrophysics, we forecast meaningful constraints on the neutrino production mechanism; for fundamental physics, vastly improved constraints on Lorentz-invariance violation. These are the first measurement forecasts of the UHE ${\nu }_{\tau }$ content.

High velocity neutron stars, observed as rapidly moving radio pulsars, are believed to gain high linear velocities—kicks in aspherical supernova explosions. The mechanism of the kick formation is probably connected with anisotropic neutrino flash, and/or anisotropic matter ejection. In this paper, we investigate a neutron star kick origin in a magnetorotational (MR) supernova explosion model. The simulations have been done for a series of core collapse supernova models with initial equatorially asymmetric magnetic fields. We have realized 2D magnetohydrodynamic simulations, considering the protoneutron star kick and explosion properties in three different asymmetric magnetic field configurations. The simulations show that in the MR supernova model protoneutron star kicks are formed with velocities up to $\sim 500\mathrm{km}/\mathrm{s}$, due to asymmetric matter ejection in jets. It may explain the observed kick velocities of some neutron stars, formed in the MR supernovae explosions.

Time-delay interferometry (TDI) is a data processing technique for space-based gravitational-wave detectors to create laser-noise-free equal-optical-path-length interferometers virtually on the ground. It relies on the interspacecraft signal propagation delays, which are delivered by intersatellite ranging monitors. Also, onboard signal propagation and processing delays have a non-negligible impact on the TDI combinations. However, these onboard delays were only partially considered in previous TDI-related research; onboard optical path lengths have been neglected. In this paper, we study onboard optical path lengths in TDI. We derive analytical models for their coupling to the second-generation TDI Michelson combinations and verify these models numerically. Furthermore, we derive a compensation scheme for onboard optical path lengths in TDI and validate its performance via numerical simulations.

Gravitational waves from subsolar mass primordial black holes could be detected in LIGO, Virgo, and KAGRA data. Here, we apply a method originally designed to look for rapidly spinning-down neutron stars, the generalized frequency-Hough transform, to search for planetary-mass primordial black holes using data from the first half of the third observing run of advanced LIGO. In this companion paper to Miller et al. [Phys. Rev. Lett. 133, 111401 (2024)], in which the main results of our search are presented, we delve into the details of the search methodology, the choices we have made regarding the parameter space to explore, the follow-up procedure we use to confirm or reject possible candidates returned in our search, and a comparison of our analytic procedure of generating upper limits to those obtained through injections.

In space-based gravitational wave detection, the gravitational force generated by the spacecraft itself at the location of the test masses, known as self-gravity, can disrupt the free-fall state of the test masses. The self-gravity effect is one of the main noise sources in gravitational wave detection. Currently, the only established method to estimate this effect before launch is the finite element calculation based on the precise spacecraft computer aided design model. In this paper, we propose a torsion pendulum experiment to measure the dominant gravitational multipole components of spacecraft to assess the self-gravity. This provides an important ground-validation approach for finite element calculations. The results of a proof-of-principle experiment show that the measurement resolution can reach $3.4\times {10}^{-11}\mathrm{m}{\mathrm{s}}^{-2}$ for differential linear acceleration, $1.6\times {10}^{-10}\mathrm{rad}{\mathrm{s}}^{-2}$ for angular acceleration, and $4.7\times {10}^{-9}{\mathrm{s}}^{-2}$ for linear gradients. These measurement resolutions are sufficient for estimating the self-gravity of Laser Interferometer Space Antenna or TianQin.