We investigate the Crewther relation at high loop order in a variety of renormalization schemes and gauges. By examining the properties of the relation in schemes other than modified minimal subtraction ($\overline{\mathrm{MS}}$) at the fixed points of quantum chromodynamics we propose a generalization of the Crewther relation that extends the $\overline{\mathrm{MS}}$ construction of Broadhurst and Kataev. A derivation based on the properties of the renormalization group equation is provided for the generalization which is tested in various scenarios.

We study the fermion pair creation phenomenon due to the time dependence of curves, where boundary conditions are imposed on a Dirac field in $2+1$ dimensions. These conditions, which lead to nontrivial relations for the normal component of the fermionic current, depend on the value of a dimensionless parameter. We show that the pair creation effect is maximized for bag boundary conditions, obtained for a particular value of that parameter. The effect is studied in terms of the effective action to extract information on the probability of vacuum decay, using an expansion in powers of the deformation of the curves with respect to straight lines. We demonstrate that the first nontrivial contributions to this process can be obtained from the electromagnetic vacuum polarization tensor for a Dirac field coupled to static boundaries.

We formulate the first-order dissipative anisotropic hydrodynamical theory for a relativistic conformal uncharged fluid, which generalizes the Bemfica-Disconzi-Noronha-Kovtun first-order viscous fluid framework. Our approach maintains causal behavior in the nonlinear regime with or without general relativity coupling, and we derive and analyze the constraints on transport coefficients imposed by causality. We demonstrate the causal and stable behavior of our theory in specific cases, including the discussion of nonlinear causality as well as stability for linearized perturbations. We apply our newly developed first-order anisotropic theory to the Bjorken flow and show how causality and stability impose constraints on the behavior of the early-time attractor.

While the main goal of the J-PARC KOTO experiment is to measure the rare decay $K_L\to {\pi }^0\nu \overline{\nu }$, the unique setup of KOTO raises the possibility to search for physics beyond the Standard Model, in an attempt to probe parts of the parameter space which are not covered by other experiments. In this paper, we test the possibility of using KOTO to search for heavy QCD axions, or axionlike particles, a well-motivated extension of the Standard Model emerging in a variety of models. In particular, we estimate the sensitivity of the current KOTO setup as well as KOTO Step 2 for various benchmark scenarios of axion coupling to the Standard Model. We find that KOTO Step 2 can probe new regions in the parameter space, while KOTO with its current form can only reaffirm the existing bounds. The obtained axion datasets are available as an update of the public code of the alpinist framework, including implementation of KOTO setups in the simulation, allowing for interpretation of various analyses as searches for axions in custom models.

We study the prospect of measuring the electroweak quantum numbers of beyond the Standard Model color sextet particles that decay into same-sign top-quark pairs. Among these particles, the color sextet scalars give rise to top quarks with the same chirality, while the top quarks coming from the color sextet vector would have opposite chirality. This difference gets encoded in the angular distributions of the bottom quarks and leptons originating from the decays of the top quarks. We utilize this feature and the energy distributions of the final-state jets and leptons to distinguish among the three possible color sextet resonances, taking into account various SM background processes at the 13 TeV LHC.

Significant effort has been devoted to searching for new fundamental forces of nature. At short length scales (below approximately 10 nm), the strongest experimental constraints come from neutron scattering from individual nuclei in gases. The leading experiments at longer length scales instead measure forces between macroscopic test masses. We propose a hybrid of these two approaches: scattering neutrons off of a target that has spatial structure at nanoscopic length scales. Such structures will give a coherent enhancement to small-angle scattering, where the new force is most significant. This can considerably improve the sensitivity of neutron scattering experiments for new forces in the 0.1–100 nm range. We discuss the backgrounds due to Standard Model interactions and a variety of potential target structures that could be used, estimating the resulting sensitivities. We show that, using only one day of beam time at a modern neutron scattering facility, our proposal has the potential to detect new forces as much as 2 orders of magnitude beyond current laboratory constraints at the appropriate length scales.

We present a numerical solution of the revised version [J. High Energy Phys. 07 (2022) 095] of the small-$x$ helicity evolution equations from [J. High Energy Phys. 01 (2016) 072, Phys. Rev. D 99, 054032 (2019)] at large $N_c$ and $N_f$. (Here $N_c$ and $N_f$ are the numbers of quark colors and flavors, respectively.) The evolution equations are double-logarithmic in the Bjorken $x$ variable, resumming powers of ${\alpha }_s{\ln }^2(1/x)$ with ${\alpha }_s$ the strong coupling constant. The large-$N_c\&N_f$ evolution we consider includes contributions of small-$x$ quark emissions and is thus more realistic than the large-$N_c$ one, which only involves gluon emissons. The evolution equations [J. High Energy Phys. 07 (2022) 095, J. High Energy Phys. 01 (2016) 072, Phys. Rev. D 99, 054032 (2019)] are written for the so-called “polarized dipole amplitudes,” which are related to the helicity distribution functions and the $g_1$ structure function. Unlike the previously reported solution [J. High Energy Phys. 08 (2020) 014] of the earlier version of helicity evolution equations at large $N_c\&N_f$ [J. High Energy Phys. 01 (2016) 072, Phys. Rev. D 99, 054032 (2019)], our solution does not exhibit periodic oscillations in $\ln (1/x)$ for $N_f<2N_c$, while only showing occasional sign reversals. For $N_f=2N_c$, we report oscillations with $\ln (1/x)$, similar to those found earlier in [J. High Energy Phys. 08 (2020) 014]. We determine the intercept of our evolution for $N_f<2N_c$ as well as the parameters of the oscillatory behavior for $N_f=2N_c$. We compare our results to the existing resummation [Z. Phys. C 72, 627 (1996)] and finite-order calculations for helicity-dependent quantities in the literature.

We search for a $B$ decay mode where one can find a peak for a $D\overline{D}$ bound state predicted in effective theories and in lattice QCD calculations, which has also been claimed from some reactions that show an accumulated strength in $D\overline{D}$ production at threshold. We find a good candidate in the $B^{+}\to K^{+}\eta \eta$ reaction, by looking at the $\eta \eta$ mass distribution. The reaction proceeds via a first step in which one has the $B^{+}\to D_s^{*+}{\overline{D}}^0$ reaction followed by $D_s^{*+}$ decay to $D^0{K}^{+}$ and a posterior fusion of $D^0{\overline{D}}^0$ to $\eta \eta$, implemented through a triangle diagram that allows the $D^0{\overline{D}}^0$ to be virtual and to produce the bound state. The choice of $\eta \eta$ to see the peak is based on results of calculations that find the $\eta \eta$ among the light pseudoscalar channels with stronger coupling to the $D\overline{D}$ bound state. We find a neat peak around the predicted mass of that state in the $\eta \eta$ mass distribution, with an integrated branching ratio for $B^{+}\to K^{+}$ ($D\overline{D}$, bound); ($D\overline{D}$, bound) $\to \eta \eta$ of the order of $1.5\times {10}^{-4}$, a large number for hadronic $B$ decays, which should motivate its experimental search.

We present a new perspective on bulk reconstruction using Berry phases in the boundary conformal field theory (CFT). Our parallel transport of modular Hamiltonians is associated to a trajectory in the space of states, which we obtain from the insertion of a source in the Euclidean path integral. Using a modular version of the extrapolate dictionary and the equivalence between modular flow in the boundary and the bulk, we show that the expectation value of the modular Berry curvature on the boundary agrees with an appropriately defined bulk symplectic form associated to the entanglement wedge. In addition, we derive a quantum information metric on the space of density matrices from the Berry curvature, which is related to the canonical energy in the bulk. We also explore the case where a state change reduces to a shape change, uncovering the coadjoint orbit structure of kinematic space in higher dimensions.

GW190521 is a short-duration, low-frequency gravitational-wave signal in the LIGO-Virgo catalogue. The signal is consistent with the ringdown and possibly some of the inspiral-merger of an intermediate-mass binary black-hole coalescence. We find that previous models of the quasinormal mode spectrum in the ringdown of GW190521 give remnant mass and spin estimates which are not fully consistent with those of many inspiral-merger-ringdown waveforms. In our own analysis, we find that ringdown models which include both the angular $l=2$, $m=1$ and $l=m=2$ fundamental quasinormal modes are in full agreement with most inspiral-merger-ringdown waveforms, and in particular with the numerical relativity surrogate NRSur7dq4. We also find some support for including the $l=3$, $m=2$ fundamental quasinormal mode in our fits, building on Capano et al.’s findings regarding a higher-frequency subdominant mode. We propose an interpretation of our GW190521 ringdown model that links precession to the excitation of $l\ne m$ quasinormal modes, but we do not rule out eccentricity or other interpretations.

Numerical simulation of strange quark stars (QSs) is challenging due to the strong density discontinuity at the stellar surface. In this paper, we report successful simulations of rapidly rotating QSs and study their oscillation modes in full general relativity. Building on top of the numerical relativity code einstein toolkit, we implement a positivity-preserving Riemann solver and a dustlike atmosphere to handle the density discontinuity at the surface. The robustness of our numerical method is demonstrated by performing stable evolutions of rotating QSs close to the Keplerian limit and extracting their oscillation modes. We focus on the quadrupolar $l=|m|=2$ $f$-mode and study whether they can still satisfy the universal relations recently proposed for rotating neutron stars (NSs). We find that two of the three proposed relations can still be satisfied by rotating QSs. For the remaining broken relation, we propose a new relation to unify the NS and QS data by invoking the dimensionless spin parameter $j$. The onsets of secular instabilities for rotating QSs are also studied by analyzing the $f$-mode frequencies. Same as the result found previously for NSs, we find that QSs become unstable to the Chandrasekhar-Friedman-Schutz instability when the angular velocity of the star $\mathrm{\Omega }\approx 3.4{\sigma }_0$ for sequences of constant central energy density, where ${\sigma }_0$ is the mode frequency of the corresponding nonrotating configurations. For the viscosity-driven instability, we find that QSs become unstable when $j\approx 0.881$ for both sequences of constant central energy density and constant baryon mass. Such a high value of $j$ cannot be achieved by realistic uniformly rotating NSs before reaching the Keplerian limit. The critical value for the ratio between the rotational kinetic energy and gravitational potential energy of rotating QSs for the onset of the instability, when considering sequences of constant baryon mass, is found to agree with an approximate value obtained for homogeneous incompressible bodies in general relativity to within 4%.

Constant-curvature solutions lie at the very core of gravitational physics, with Schwarzschild and (anti-)de Sitter being two of the most paradigmatic examples. Although such a kind of solutions are very well-known in general relativity, that is not the case for theories of gravity beyond the Einsteinian paradigm. In this article, we provide a systematic overview on $f(R)$ models allowing for constant-curvature solutions, as well as of the constant-curvature solutions themselves. We conclude that the vast majority of these $f(R)$ models suffer, in general, from several shortcomings rendering their viability extremely limited, when not ruled out by physical evidence. Among these deficiencies are instabilities (including previously unforeseen strong-coupling problems) and issues limiting the predictive power of the models. Furthermore, we will also show that most $f(R)$-exclusive constant-curvature solutions also exhibit a variety of unphysical properties.

Large High Altitude Air Shower Observatory (LHAASO) opens the window of ultra-high-energy (UHE) photon detection, broadens the path of testing basic physical concepts such as Lorentz symmetry, and brings the possibility of potential high-energy physical phenomenon research such as photon decay and electron decay. Currently, the UHE photons from LHAASO observation set strict constraints on photon and electron Lorentz symmetry violation (LV) effects. To obtain a global impression of the photon-electron LV parameter plane, we make a detailed analysis for photon decay and electron decay. Our discussion gives the corresponding decay thresholds and energy-momentum distributions in different LV parameter configurations. We get corresponding constraints on the photon LV parameter, electron LV parameter and the photon-electron LV parameter plane from LHAASO observation. For the space allowed for LV effect, that is beyond relativity, we also provide corresponding boundaries from LHAASO observation.

Scalar ultralight dark matter (ULDM) interacting with neutrinos can induce, under certain conditions, time dependent modifications to neutrino oscillation probabilities. The limit in which the ULDM perturbation can be treated as constant throughout the neutrino propagation time has been addressed by several previous works. We complement these by systematically analyzing the opposite limit—accounting for the temporal variations of the ULDM field by solving time dependent Schrödinger equations. In particular, we study a novel two-generations-like $CP$ violating (CPV) signature unique to rapidly oscillating ULDM. We derive the leading order, time dependent corrections to the oscillation probabilities, for both $CP$ conserving and CPV couplings, and explain how they can be measured in current and future experiments.

This work presents the first lattice-QCD calculation of the twist-3 axialquark generalized parton distributions (GPDs) for the proton using the large-momentum effective theory approach. We calculate matrix elements with momentum-boosted proton states and a nonlocal axial operator. The calculation is performed using one ensemble of two degenerate light, a strange and a charm quark ($N_f=2+1+1$) of maximally twisted mass fermions with a clover term. The ensemble has a volume ${32}^3\times 64$ and lattice spacing 0.0934 fm and corresponds to a pion mass of 260 MeV. The matrix elements are calculated for three values of the proton momentum, namely 0.83, 1.25, and 1.67 GeV. The light-cone GPDs are defined in the symmetric frame, which we implement here with a (negative) 4-momentum transfer squared of 0.69, 1.38, and $2.76{\mathrm{GeV}}^2$, all at zero skewness. We also conduct several consistency checks, including assessing the local limit of the twist-3 GPDs and examining the Burkhardt-Cottingham-type as well as Efremov-Teryaev-Leader-type sum rules.

We present the first full analytic results of next-to-next-to-leading order (NNLO) QCD corrections to the top-quark decay width $\mathrm{\Gamma }(t\to Wb)$ by calculating the imaginary part of three-loop top-quark self-energy diagrams. The results are all expressed in terms of harmonic polylogarithms and valid in the whole region $0\le m_W^2\le m_t^2$. The expansions in the $m_W^2\to 0$ and $m_W^2\to m_t^2$ limits coincide with previous studies. Our results can also be taken as the exact prediction for the lepton invariant mass spectrum in semileptonic $b\to u$ decays. We also analytically compute the decay width including the off shell $W$ boson effect up to NNLO in QCD for the first time. Combining these contributions with electroweak corrections and the finite $b$-quark mass effect, we determine the most precise top-quark width to be 1.331 GeV for $m_t=172.69\mathrm{GeV}$. The total theoretical uncertainties including those from renormalization scale choice, top-quark mass renormalization scheme, input parameters, and missing higher-order corrections are scrutinized and found to be less than 1%.

We study radiative corrections to low-energy charged-current processes involving nucleons, such as neutron beta decay and (anti)neutrino-nucleon scattering within a top-down effective-field-theory approach. We first match the Standard Model to the low-energy effective theory valid below the weak scale and, using renormalization group equations with anomalous dimensions of $\mathcal{O}(\alpha ,\alpha {\alpha }_s,{\alpha }^2)$, evolve the resulting effective coupling down to the hadronic scale. Here, we first match to heavy-baryon chiral perturbation theory and subsequently, below the pion-mass scale, to a pionless effective theory, evolving the effective vector coupling with anomalous dimensions of $\mathcal{O}(\alpha ,{\alpha }^2)$ all the way down to the scale of the electron mass, relevant for beta decays. We thus provide a new evaluation of the “inner” radiative corrections to the vector coupling constant and to the neutron decay rate, discussing differences with the previous literature. Using our new result for the radiative corrections, we update the extraction of the Cabibbo-Kobayashi-Maskawa matrix element $V_{ud}$ from the neutron decay.

We report on a flux-integrated multidifferential measurement of charged-current muon neutrino scattering on argon with one muon and one proton in the final state using the Booster Neutrino Beam and MicroBooNE detector at Fermi National Accelerator Laboratory. The data are studied as a function of various kinematic imbalance variables and of a neutrino energy estimator, and are compared to a number of event generator predictions. We find that the measured cross sections in different phase-space regions are sensitive to nuclear effects. Our results provide precision data to test and improve the neutrino-nucleus interaction models needed to perform high-accuracy oscillation analyses. Specific regions of phase space are identified where further model refinements are most needed.

We present novel constraints on boosted light dark matter particles (denoted as “$\chi$”) from evaporating primordial black holes (PBHs) using $205.4\mathrm{kg}·\mathrm{day}$ data from the China Jinping Underground Laboratory’s CDEX-10 p-type point contact germanium detector with a 160 eVee analysis threshold. $\chi$ from PBHs with masses ranging from $1\times {10}^{15}\mathrm{g}$ to $7\times {10}^{16}\mathrm{g}$ are searched in this work. In the presence of PBH abundance compatible with present bounds, our result excludes the $\chi$-nucleon elastic-scattering cross section region from $3.4\times {10}^{-32}{\mathrm{cm}}^2$ to $2.3\times {10}^{-29}{\mathrm{cm}}^2$ for $\chi$ of 1 keV to 24 MeV from PBHs with masses of $5\times {10}^{15}\mathrm{g}$, as well as from $1.1\times {10}^{-28}{\mathrm{cm}}^2$ to $7.6\times {10}^{-28}{\mathrm{cm}}^2$ for $\chi$ of 1 keV to 0.6 MeV from PBHs with masses of $7\times {10}^{16}\mathrm{g}$. If the $\chi$-nucleon elastic-scattering cross section can be determined in the future, the abundance of PBHs may be severely constrained by $\chi$ evaporation. With the lower threshold (160 eVee) of the CDEX-10 experiment compared to the previously used experiments, this work allows for a better reach at soft spectra produced by heavier PBHs, which demonstrates the vast potential of such a technical route to pursue $\chi$ from larger PBHs with a low threshold.

A measurement of charm mixing and $CP$-violating parameters is reported, using $\overline{B}\to D^0(\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}){\mu }^{-}{\overline{\nu }}_{\mu }X$ decays reconstructed in proton-proton collisions collected by the LHCb experiment during the years 2016 to 2018, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$. The measured mixing and $CP$-violating parameters are $x_{CP}=[4.29\pm 1.48(\mathrm{stat})\pm 0.26(\mathrm{syst})]\times {10}^{-3}$, $y_{CP}=[12.61\pm 3.12(\mathrm{stat})\pm 0.83(\mathrm{syst})]\times {10}^{-3}$, $\mathrm{\Delta }x=[-0.77\pm 0.93(\mathrm{stat})\pm 0.28(\mathrm{syst})]\times {10}^{-3}$, $\mathrm{\Delta }y=[3.01\pm 1.92(\mathrm{stat})\pm 0.26(\mathrm{syst})]\times {10}^{-3}$. The results are complementary to and consistent with previous measurements. A combination with the recent LHCb analysis of $D^{*+}\to D^0(\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}){\pi }^{+}$ decays is reported.