Normalizing the recent LHCb measurement of ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c\tau \overline{\nu }$ to the standard model (SM) prediction for the ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c\mu \overline{\nu }$ rate, instead of a LEP measurement, provides a more consistent comparison with the SM prediction for the lepton flavor universality ratio $R({\mathrm{\Lambda }}_c)$. This modestly increases $R({\mathrm{\Lambda }}_c)$ compared to the quoted LHCb result, such that it no longer hints at a suppression compared to the SM, which would be hard to accommodate in new physics scenarios that enhance $R(D^{(*)})$. We point out that the fraction of excited states in inclusive semileptonic ${\mathrm{\Lambda }}_b$ decay may be significantly greater than the corresponding fraction in $B$ decays. Possible implications are speculated upon.

The inspiral-merger-ringdown (IMR) consistency test checks the consistency of the final mass and final spin of a binary black hole merger remnant, independently inferred via the inspiral and merger-ringdown parts of the waveform. As binaries are expected to be nearly circularized when entering the frequency band of ground-based detectors, tests of general relativity (GR) currently employ quasicircular waveforms. We quantify the effect of residual orbital eccentricity on the IMR consistency test. We find that eccentricity causes a significant systematic bias in the inferred final mass and spin of the remnant black hole at an orbital eccentricity (defined at 10 Hz) of $e_0\gtrsim 0.1$ in the LIGO band (for a total binary mass in the range $65–200M_{\odot }$). For binary black holes observed by Cosmic Explorer (CE), the systematic bias becomes significant for $e_0\gtrsim 0.015$ (for $200–600M_{\odot }$ systems). This eccentricity-induced bias on the final mass and spin leads to an apparent inconsistency in the IMR consistency test, manifesting as a false violation of GR. Hence, eccentric corrections to waveform models are important for constructing a robust test of GR, especially for third-generation detectors. We also estimate the eccentric corrections to the relationship between the inspiral parameters and the final mass and final spin; they are shown to be quite small.

Anomalies are a powerful way to gain insight into possible lattice regularizations of a quantum field theory. In this work, we argue that the continuum anomaly for a given symmetry can be matched by a manifestly symmetric, local, lattice regularization in the same spacetime dimensionality only if (i) the symmetry action is offsite, or (ii) if the continuum anomaly is reproduced exactly on the lattice. We consider lattice regularizations of a class of prototype models of QCD: the ($1+1$)-dimensional asymptotically free Grassmannian nonlinear sigma model ($\mathrm{NL}\sigma \mathrm{Ms}$) with a $\theta$ term. Using the Grassmannian $\mathrm{NL}\sigma \mathrm{Ms}$ as a case study, we provide examples of lattice regularizations in which both possibilities are realized. For possibility (i), we argue that Grassmannian $\mathrm{NL}\sigma \mathrm{Ms}$ can be obtained from $\mathrm{SU}(N)$ antiferromagnets with a well-defined continuum limit, reproducing both the infrared physics of $\theta$ vacua and the ultraviolet physics of asymptotic freedom. These results enable the application of new classical algorithms to lattice Monte Carlo studies of these quantum field theories, and provide a viable realization suited for their quantum simulation. On the other hand, we show that, perhaps surprisingly, the conventional lattice regularization of $\theta$ vacua due to Berg and Lüscher reproduces the anomaly exactly on the lattice, providing a realization of the second possibility.

We map the distribution of unpolarized quarks inside a unpolarized pion as a function of the quark’s transverse momentum, encoded in unpolarized transverse momentum distributions (TMDs). We extract the pion TMDs from available data of unpolarized pion-nucleus Drell–Yan processes, where the cross section is differential in the lepton-pair transverse momentum. In the cross section, pion TMDs are convoluted with nucleon TMDs that we consistently take from our previous studies. We obtain a fairly good agreement with data. We present also predictions for pion-nucleus scattering that is being measured by the COMPASS Collaboration.

Processes with precisely known cross sections, like neutrino-electron elastic scattering ($\nu e^{-}\to \nu e^{-}$) and inverse muon decay (${\nu }_{\mu }{e}^{-}\to {\mu }^{-}{\nu }_e$) have been used by $\mathrm{M}\mathrm{I}\mathrm{N}\mathrm{E}\mathrm{R}\nu \mathrm{A}$ to constrain the uncertainty on the neutrinos at the main injector (NuMI) neutrino beam flux. This work presents a new measurement of neutrino elastic scattering with electrons using the medium energy ${\overline{\nu }}_{\mu }$-enhanced NuMI beam. A sample of 578 events after background subtraction is used in combination with the previous measurement on the ${\nu }_{\mu }$ beam and the inverse muon decay measurement to reduce the uncertainty on the ${\nu }_{\mu }$ flux in the ${\nu }_{\mu }$-enhanced beam from 7.6% to 3.3% and the ${\overline{\nu }}_{\mu }$ flux in the ${\overline{\nu }}_{\mu }$-enhanced beam from 7.8% to 4.7%.

We propose to search for $CP$ violation through the twofold angular distributions in the four-body decays of bottom and charmed hadrons. The two polar angles in the twofold angular distributions are correlated, to which the interferences of intermediate resonances are one important origin. These interferences will leave tracks in the twofold angular distributions, with which the $CP$ violation can be studied. Special attention is paid to the case when all the intermediate resonances are different, which is unique to four-body decays. It is suggested to look for $CP$ violation in four-body decays such as ${\mathrm{\Lambda }}_b^0\to p{\pi }^{-}{\pi }^{+}{\pi }^{-}$ through the analysis of the twofold angular distributions. The method proposed in this paper is also widely applicable to other four-body decays processes.

The method of nonlinear realizations is a convenient tool for building dynamical realizations of a Lie group, which relies solely upon structure relations of the corresponding Lie algebra. The goal of this work is to discuss advantages and limitations of the method, which is here applied to construct perfect fluid equations with conformal symmetry. Four cases are studied in detail, which include the Schrödinger group, the $\ell$-conformal Galilei group, the Lifshitz group, and the relativistic conformal group.

Operators with integer scaling dimensions in even-dimensional conformal field theories exhibit well-known type-B Weyl anomalies. In general, these anomalies depend nontrivially on exactly marginal couplings. We study the corresponding fully covariantized anomaly functional on conformal manifolds in several examples. We show that a natural consequence of the Wess-Zumino consistency condition is that the anomalies are covariantly constant with respect to the exactly marginal couplings. The argument is general and applies even when the conformal symmetry is spontaneously broken on moduli spaces of vacua.

We study numerically the 6D (2,0) superconformal bootstrap using the soft-actor-critic (SAC) algorithm as a stochastic optimizer. We focus on the four-point functions of scalar superconformal primaries in the energy-momentum multiplet. Starting from the supergravity limit, we perform searches for adiabatically varied central charges and derive two curves for a collection of 80 conformal field theory (CFT) data (70 of these data correspond to unprotected long multiplets and 10 to protected short multiplets). We conjecture that the two curves capture the $A$- and $D$-series (2,0) theories. Our results are competitive when compared to the existing bounds coming from standard numerical bootstrap methods, and data obtained using the OPE inversion formula. With this paper we are also releasing our python implementation of the SAC algorithm, bootstop. The paper discusses the main functionality features of this package.

We examine the relationship between three approaches (Hadamard, DeWitt-Schwinger, and adiabatic) to the renormalization of expectation values of field operators acting on a charged quantum scalar field. First, we demonstrate that the DeWitt-Schwinger representation of the Feynman Green’s function is a particular case of the Hadamard representation. Next, we restrict attention to a spatially flat Friedmann-Lemaître-Robertson-Walker universe with time-dependent, purely electric, background electromagnetic field, considering two-, three-, and four-dimensional space-times. Working to the order required for the renormalization of the stress-energy tensor, we find the adiabatic and DeWitt-Schwinger expansions of the Green’s function when the space-time points are spatially separated. In two and four dimensions, the resulting DeWitt-Schwinger and adiabatic expansions are identical. In three dimensions, the DeWitt-Schwinger expansion contains terms of adiabatic order 4 that are not necessary for the renormalization of the stress-energy tensor and hence absent in the adiabatic expansion. The equivalence of the DeWitt-Schwinger and adiabatic approaches to renormalization in the scenario considered is thereby demonstrated in even dimensions. In odd dimensions the situation is less clear and further investigation is required in order to determine whether adiabatic renormalization is a locally covariant renormalization prescription.

The lightlike limit of boosted black hole solutions with one angular momentum is considered for $D\ge 4$ dimensions. The boost is performed parallel to the angular momentum and the lightlike limit is done by means of perturbative expansions. We show that for $D=4$ and $D>5$ the lightlike limit cannot be extended inside the ring singularity. Then, for $D=5$ we discuss the arising of trapped surfaces in the head-on collision. We find that, inside the validity of the performed perturbative analysis, a trapped surface with topology $\mathbb{R}\times {\mathbb{S}}_1\times {\mathbb{S}}_1$ seems to appear over the past light cone of the collision below a critical value of the Kerr parameter.

Noncanonical cosmology with an uplifted Higgs vacuum expectation value (Higgs-VEV) in the early universe is believed to provide the solution for existing tensions within the $\mathrm{\Lambda }$-cold-dark-matter ($\mathrm{\Lambda }\mathrm{CDM}$) regime. We recently proposed a theoretical model called axion-Higgs to explore this framework. The axion-Higgs model features an ultralight axion with mass $m_a\sim {10}^{-29}\mathrm{eV}$, which couples to the Higgs field such that the Higgs-VEV is driven by the axion background evolution. Phenomenologically, the axion-Higgs model is equivalent to $\mathrm{\Lambda }\mathrm{CDM}+m_e+{\omega }_a$ which is defined as $\mathrm{\Lambda }\mathrm{CDM}$ with electron mass variation and the presence of an ultralight axion. In this paper, we perform Markov chain Monte Carlo analyses to investigate the parameter space of axion-Higgs and compare it with $\mathrm{\Lambda }\mathrm{CDM}$, $\mathrm{\Lambda }\mathrm{CDM}+m_e$ where only electron mass variation is allowed, and $\mathrm{\Lambda }\mathrm{CDM}+{\omega }_a$ where only an ultralight axion is present. Combining observational data from Cosmic Microwave Background, Baryon Acoustic Oscillations, weak-lensing cosmic shear survey we found $H_0=69.4\pm 1.3\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$, which reduces the Hubble tension to approximately $2.4\sigma$. Including data from supernovae Type IA and local Hubble measurement from SH0ES we found $H_0=71.34\pm 0.96\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$. The presence of this Higgs-VEV-driving axion may be tested by atomic clock and quasar spectral measurements in the near future.

We provide the first rigorous numerical analysis of the longitudinal-transverse double-spin asymmetry $A_{LT}$ in electron-nucleon and proton-proton collisions for the case where only a single pion, jet, or photon is detected in the final state. Given recent extractions of certain, previously unknown, nonperturbative functions, we are able to compute contributions from all terms relevant for $A_{LT}$ and make realistic predictions for the observable at Jefferson Lab (JLab) 12 GeV, COMPASS, the future Electron-Ion Collider, and the Relativistic Heavy Ion Collider. We also compare our results to a JLab 6 GeV measurement, which are the only data available for this type of reaction. The twist-3 nature of $A_{LT}$ makes it a potentially fruitful avenue to probe quark-gluon-quark correlations in hadrons as well as provide insights into dynamical quark mass generation in QCD.

Measurements by the CMS experiment [S. Chatrchyan et al. (CMS Collaboration), J. High Energy Phys. 04 (2014) 103; A. M. Sirunyan et al. (CMS Collaboration), J. High Energy Phys. 11 (2020) 001] reveal a deficit of charged particle tracks in events with higher $\mathrm{\Upsilon }(\mathrm{nS})$ states. This observation is suggested to be a manifestation of the excited bottomonia suppression in $pp$ interactions. Transverse mass ($m_{\mathrm{T}}$) scaling can be implied to check this assumption in an independent way. The scaling has been observed for a wide range of particle species in proton-proton collisions at various energies from the SPS to RHIC and the LHC. The observed scaling is known to be different for baryons and mesons, and this work presents a comprehensive study of the $m_{\mathrm{T}}$-scaling of mesons at LHC energies with a focus on heavier mesons. The study demonstrates patterns in the scaling properties of mesons, which are related to the particle quark content. In particular, light species and ground-state quarkonia obey the same scaling, whereas open-flavor particles deviate from it because their spectra are significantly harder. The magnitude of deviation depends on the flavor of the heaviest quark in the meson. By extending the $m_{\mathrm{T}}$-scaling assumption to the excited bottomonia states, it is observed that the measured cross sections of $\mathrm{\Upsilon }(2\mathrm{S})$ and $\mathrm{\Upsilon }(3\mathrm{S})$ are reduced by factors of 1.6 and 2.4 compared to the expectation from the scaling. This observation is consistent with recently observed differences between the event-activity dependence of different $\mathrm{\Upsilon }(\mathrm{nS})$ meson states.

Information on the phase structure of strongly interacting matter at high baryon densities can be gained from observations of neutron stars and their detailed analysis. In the present work Bayesian inference methods are used to set constraints on the speed of sound in the interior of neutron stars, based on recent multimessenger data in combination with limiting conditions from nuclear physics at low densities. Two general parametric representations are introduced for the sound speed $c_s$ in order to examine the independence with respect to choices for the parametrization of priors. Credible regions for neutron star properties are analyzed, in particular with reference to the quest for possible phase transitions in cold dense matter. The evaluation of Bayes factors implies extreme evidence for a violation of the conformal bound, $c_s^2\le 1/3$, inside neutron stars. Given the presently existing data base, it can be concluded that the occurrence of a first-order phase transition in the core of even a two-solar-mass neutron star is unlikely, while a continuous crossover cannot be ruled out. At the same time it is pointed out that the discovery of a superheavy neutron star with a mass $M\sim 2.3–2.4M_{\odot }$ would strengthen evidence for a phase change in the deep interior of the star.

The $\nu \mathrm{BDX}\text{−}\mathrm{DRIFT}$ Collaboration seeks to detect low-energy nuclear recoils from $\mathrm{CE}\nu \mathrm{NS}$ or BSM interactions at FNAL. Backgrounds due to rock neutrons are an important concern. We present a genie and geant4 based model to estimate backgrounds from rock neutrons produced in neutrino-nucleus interactions within the rock walls surrounding the underground halls. This model was bench-marked against the 2009 COUPP experiment performed in the MINOS hall in the NuMI neutrino beam, and agreement is found between experimental results and the modeled result to within 30%. Working from this validated model, a similar two-stage simulation was performed to estimate recoil backgrounds in the $\nu \mathrm{BDX}\text{−}\mathrm{DRIFT}$ detector across several beamlines. In the first stage utilizing geant4, neutrons were tallied exiting the walls of a rectangular underground hall utilizing four different neutrino beam configurations. These results are presented for use by other underground experiments requiring estimations of their rock neutron backgrounds. For $\nu \mathrm{BDX}\text{−}\mathrm{DRIFT}$, the second stage propagated neutrons from the walls and recorded energy deposited within a scintillator veto surrounding the detector and nuclear recoils within the detector’s fiducial volume. The directional signal from the $\nu \mathrm{BDX}\text{−}\mathrm{DRIFT}$ detector allows additional background subtraction. A sample calculation of a $10{\mathrm{m}}^3·\mathrm{yr}$ exposure to the NuMI low-energy beam configuration shows a $\mathrm{CE}\nu \mathrm{NS}$ signal-to-noise ratio of $\sim 2.5$.

The nonforward eikonal scattering matrix for dipole-proton scattering at high-energy obtains an imaginary part due to a $C$-odd three gluon exchange. We present numerical estimates for the perturbative odderon amplitude as a function of dipole size, impact parameter, their relative azimuthal angle, and light-cone momentum cutoff $x$. The proton is approximated as ${\psi }_{\mathrm{qqq}}|qqq⟩+{\psi }_{\mathrm{qqqg}}|qqqg⟩$, where ${\psi }_{\mathrm{qqq}}$ is a nonperturbative three-quark model wave function while the gluon emission is computed in light-cone perturbation theory. We find that the odderon amplitude increases as $x$ decreases from 0.1 to 0.01. At yet lower $x$, the reversal of this energy dependence would reflect the onset of universal small-$x$ renormalization group evolution.

Gravitational wave bursts are transient signals distinct from compact binary mergers that arise from a wide variety of astrophysical phenomena. Because most of these phenomena are poorly modeled, the use of traditional search methods such as matched filtering is excluded. Bursts include short ($<10\mathrm{s}$) and long (from 10 s to a few hundred seconds) duration signals for which the detection is constrained by environmental and instrumental transient noises called glitches. Glitches contaminate burst searches, reducing the amount of useful data and limiting the sensitivity of current algorithms. It is therefore of primordial importance to locate and distinguish them from potential burst signals. We propose training a convolutional neural network to detect glitches in the time-frequency space of the cross-correlated LIGO noise. We show that our network is retrieving more than 95% of the glitches while being trained on only a subset of the existing glitch classes, thus highlighting the sensitivity of the network to completely new glitch classes.

The measurement of multipole moments of astrophysical objects through gravitational wave (GW) observations provides a novel way to distinguish black holes from other astrophysical objects. This paper studies the gravitational wave radiation from an extreme mass ratio inspiral (EMRI) system consisting of a supermassive Kerr black hole (the primary object) and a spinning stellar-mass compact object (the secondary object). The quadrupolar deformation induced by the spin of the secondary is different for different astrophysical objects. We compute the effect of the quadrupolar deformation on the GW phase and provide an order of magnitude estimate of whether LISA can distinguish different astrophysical objects through GW phase measurement. We find that although LISA cannot distinguish between a black hole and a neutron star, it can distinguish black holes from a large variety of highly spinning astrophysical objects like superspinars and highly deformable exotic compact objects like boson stars for EMRI systems with relatively large mass ratio ($q\sim {10}^{-4}$). Furthermore, we show that the effect of spin-induced quadrupolar deformation on the GW phase for white dwarf and brown dwarf-EMRI systems can be quite significant even for small values of mass ratio ($q\lesssim {10}^{-6}$).

We investigate the out-of-equilibrium dynamics of viscous fluids in a spatially flat Friedmann-Lemaître-Robertson-Walker cosmology using the most general causal and stable viscous energy-momentum tensor defined at first order in spacetime derivatives. In this new framework a pressureless viscous fluid having equilibrium energy density $\rho$ can evolve to an asymptotic future solution in which the Hubble parameter approaches a constant while $\rho \to 0$, even in the absence of a cosmological constant (i.e., $\mathrm{\Lambda }=0$). Thus, while viscous effects in this model drive an accelerated expansion of the universe, the equilibrium energy density itself vanishes, leaving behind only the acceleration. This behavior emerges as a consequence of causality in first-order theories of relativistic fluid dynamics and it is fully consistent with Einstein’s equations.