We study the impact of the recently computed mixed QCD-electroweak corrections to the production of $W$ and $Z$ bosons at the LHC on the value of the $W$ mass extracted from the transverse momentum distribution of charged leptons from $W$ decays. Using the average lepton transverse momenta in $W$ and $Z$ decays as simplified observables for the determination of the $W$ mass, we estimate that mixed QCD-electroweak corrections can shift the extracted value of the $W$ mass by up to $\mathcal{O}(20)\mathrm{MeV}$, depending on the kinematic cuts employed to define fiducial cross sections for $Z$ and $W$ production. Since the target precision of the $W$-mass measurement at the LHC is $\mathcal{O}(10)\mathrm{MeV}$, our results emphasize the need for fully differential computations of mixed QCD-electroweak corrections and a careful analysis of their potential impact on the determination of the $W$ mass.

A search is performed for the electroweak pair production of charginos and associated production of a chargino and neutralino, each of which decays through an $R$-parity-violating coupling into a lepton and a $W$, $Z$, or Higgs boson. The trilepton invariant-mass spectrum is constructed from events with three or more leptons, targeting chargino decays that include an electron or muon and a leptonically decaying $Z$ boson. The analyzed dataset corresponds to an integrated luminosity of $139{\mathrm{fb}}^{-1}$ of proton-proton collision data produced by the Large Hadron Collider at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ and collected by the ATLAS experiment between 2015 and 2018. The data are found to be consistent with predictions from the Standard Model. The results are interpreted as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model. Limits are also set on the production of charginos and neutralinos for a minimal supersymmetric Standard Model with an approximate $B-L$ symmetry. Charginos and neutralinos with masses between 100 and 1100 GeV are excluded depending on the assumed decay branching fractions into a lepton (electron, muon, or $\tau$ lepton) plus a boson ($W$, $Z$, or Higgs).

We brute-force evaluate the vacuum character for $\mathcal{N}=2$ vertex operator algebras labeled by crystallographic complex reflection groups $G(k,1,1)={\mathbb{Z}}_k$, $k=3$, 4, 6, and $G(3,1,2)$. For ${\mathbb{Z}}_{3,4}$ and $G(3,1,2)$ these vacuum characters have been conjectured to respectively reproduce the Macdonald limit of the superconformal index for rank one and rank two S-fold $\mathcal{N}=3$ theories in four dimensions. For the ${\mathbb{Z}}_3$ case, and in the limit where the Macdonald index reduces to the Schur index, we find agreement with predictions from the literature.

Values of the Hubble constant between the direct measurements from various independent local observations and that inferred from the cosmic microwave background with the $\mathrm{\Lambda }$-cold-dark-matter model are in tension with persistent significance. We propose a late-time inhomogeneous resolution suggesting that a chameleon field coupled to a local overdensity of matter could be trapped at a higher potential energy density as an effective cosmological constant driving the local expansion rate faster than that of the background with lower matter density. We illustrate this mechanism in a toy model in which a region with only 20% overdensity of matter is sufficient to resolve the Hubble tension, and the Hubble constant measured by the local distance ladders could be accommodated by the chameleon coupled to the observed overdensities from the large-scale structure surveys.

Proto-neutron stars forming a few seconds after core-collapse supernovae are hot and dense environments where hyperons can be efficiently produced by weak processes. By making use of various state-of-the-art supernova simulations combined with the proper extensions of the equations of state including $\mathrm{\Lambda }$ hyperons, we calculate the cooling of the star induced by the emission of dark particles $X^0$ through the decay $\mathrm{\Lambda }\to n{X}^0$. Comparing this novel energy-loss process to the neutrino cooling of SN 1987A allows us to set a stringent upper limit on the branching fraction, $\mathrm{BR}(\mathrm{\Lambda }\to n{X}^0)\le 8\times {10}^{-9}$, that we apply to massless dark photons and axions with flavor-violating couplings to quarks. We find that the new supernova bound can be orders of magnitude stronger than other limits in dark-sector models.

It was recently demonstrated that $\mathcal{N}=1$, 2, 3, 4 super-Schwarzian derivatives can be constructed by applying the method of nonlinear realizations to finite-dimensional superconformal groups $OSp(1|2)$, $SU(1,1|1)$, $OSp(3|2)$, $SU(1,1|2)$, respectively, thus avoiding the use of superconformal field theory techniques. In this work, a similar construction is applied to the exceptional supergroup $D(2,1;a)$, which describes the most general $\mathcal{N}=4$ supersymmetric extension of $SL(2,R)$, with the aim to study possible candidates for a $D(2,1;a)$ super-Schwarzian derivative.

In the presence of the fluid helicity $\mathit{v}·\mathit{\omega }$, the magnetic field induces an electric current of the form $\mathit{j}=C_{\mathrm{HME}}(\mathit{v}·\mathit{\omega })\mathit{B}$. This is the helical magnetic effect (HME). We show that for massless Dirac fermions with charge $e=1$, the transport coefficient $C_{\mathrm{HME}}$ is fixed by the chiral anomaly coefficient $C=1/(2{\pi }^2)$ as $C_{\mathrm{HME}}=C/2$ independently of interactions. We show the conjecture that the coefficient of the magnetovorticity coupling for the local vector charge, $n=C_{B\omega }\mathit{B}·\mathit{\omega }$, is related to the chiral anomaly coefficient as $C_{B\omega }=C/2$. We also discuss the condition for the emergence of the helical plasma instability that originates from the HME.

The detection of gravitational-wave signals from coalescing eccentric binary black holes would yield unprecedented information about the formation and evolution of compact binaries in specific scenarios, such as dynamical formation in dense stellar clusters and three-body interactions. The gravitational-wave searches by the ground-based interferometers, LIGO and Virgo, rely on analytical waveform models for binaries on quasi-circular orbits. Eccentric merger waveform models are less developed, and only a few numerical simulations of eccentric mergers are publicly available, but several eccentric inspiral models have been developed from the post-Newtonian expansion. Here we present a novel method to convert the dominant quadrupolar mode of any circular analytical binary-black-hole model into an eccentric model. First, using numerical simulations, we examine the additional amplitude and frequency modulations of eccentric signals that are not present in their circular counterparts. Subsequently, we identify suitable analytical descriptions of those modulations and inter-polate key parameters from twelve numerical simulations designated as our training dataset. This allows us to reconstruct the modulated amplitude and phase of any waveform up to mass ratio 3 and eccentricity 0.2. We find that the minimum overlap of the new model with numerical simulations is around 0.98 over all of our test dataset that are scaled to a $50M_{\odot }$ black-hole binary starting at 35 Hz with aLIGO $\mathrm{A}+$ design sensitivity. A python package pyrex easily carries out the computation of this method.

Although the idea that there is a maximum force in nature seems untenable, we explore whether this concept can make sense in the restricted context of black holes. We discuss uniformly accelerated and cosmological black holes and we find that, although a maximum force acting on these black holes can in principle be introduced, this concept is rather tautological.

We present stationary solutions of geometrically thick discs (or tori) endowed with a self-consistent toroidal magnetic field distribution surrounding a nonrotating black hole in an analytical, static, spherically-symmetric $f(R)$-gravity background. These $f(R)$-gravity models introduce a Yukawa-like modification to the Newtonian potential, encoded in a single parameter $\delta$ which controls the strength of the modified potential and whose specific values affect the disc configurations when compared to the general relativistic case. Our models span different magnetic field strengths, from purely hydrodynamical discs to highly magnetized tori. The characteristics of the solutions are identified by analyzing the central density, mass, geometrical size, angular size, and the black hole metric deviations from the Schwarzschild space-time. In the general relativistic limit ($\delta =0$) our models reproduce previous results for a Schwarzschild black hole. For small values of the $\delta$ parameter, corresponding to $\sim 10\%$ deviations from general relativity, we find variations of $\sim 2\%$ in the event horizon size, a $\sim 5\%$ shift in the location of the inner edge and center of the disc, while the outer edge increases by $\sim 10\%$. Our analysis for $|\delta |>0.1$, however, reveals notable changes in the black hole space-time solution which have a major impact in the morphological and thermodynamical properties of the discs. The comparison with general relativity is further investigated by computing the size of the photon ring produced by a source located at infinity. This allows us to place constraints on the parameters of the $f(R)$-gravity model based on the Event Horizon Telescope observations of the size of the light ring in M87 and $\mathrm{Sgr}{\mathrm{A}}^{*}$.

We determine the upper limit on the mass of the lightest neutrino from the most robust recent cosmological and terrestrial data. Marginalizing over possible effective relativistic degrees of freedom at early times ($N_{\mathrm{eff}}$) and assuming normal mass ordering, the mass of the lightest neutrino is less than 0.037 eV at 95% confidence; with inverted ordering, the bound is 0.042 eV. These results improve upon the strength and robustness of other recent limits and constrain the mass of the lightest neutrino to be barely larger than the largest mass splitting. We show the impacts of realistic mass models and different sources of $N_{\mathrm{eff}}$.

Light new vector bosons can be produced gravitationally through quantum fluctuations during inflation; if these particles are feebly coupled and cosmologically metastable, they can account for the observed dark matter abundance. However, in minimal anomaly-free $U(1)$ extensions to the Standard Model, these vectors generically decay to neutrinos if at least one neutrino mass eigenstate is sufficiently light. If these decays occur between neutrino decoupling and cosmic microwave background (CMB) freeze-out, the resulting radiation energy density can contribute to $\mathrm{\Delta }{N}_{\mathrm{eff}}$ at levels that can ameliorate the Hubble tension and be discovered with future CMB and relic neutrino detection experiments. Since the additional neutrinos are produced from vector decays after Big Bang Nucleosynthesis (BBN), this scenario predicts $\mathrm{\Delta }{N}_{\mathrm{eff}}>0$ at recombination, but $\mathrm{\Delta }{N}_{\mathrm{eff}}=0$ during BBN. Furthermore, due to a fortuitous cancellation, the contribution to $\mathrm{\Delta }{N}_{\mathrm{eff}}$ is approximately mass independent.

In scale-invariant models of fundamental physics, mass scales are generated by spontaneous symmetry breaking. In this work, we study inflation in scale-invariant $R^2$ gravity, in which the Planck mass is generated by a scalar field, which is responsible for spontaneous breaking of scale symmetry. If the self-interactions of the scalar field are nonzero, a cosmological constant is generated, which can be potentially quite large. To avoid fine-tuning at late times, we introduce another scalar field which drives the classical cosmological constant to zero during inflation. Working in the Einstein frame, we find that due to a conserved Noether current, the corresponding three-field inflationary model (consisting of the two scalar fields plus the scalaron) becomes effectively a two-field model. The prize to be paid for introducing the field which cancels the classical cosmological constant at the end of inflation is that the running of the spectral index and the running of the running can be quite large due to entropy perturbations during inflation, making the model testable with future cosmological experiments.

Scalar field theories with particular $U(1)$-symmetric potentials contain nontopological soliton solutions called Q-balls. Promoting the $U(1)$ to a gauge symmetry leads to the more complicated situation of gauged Q-balls. The soliton solutions to the resulting set of nonlinear differential equations have markedly different properties, such as a maximal possible size and charge. Despite these differences, we discover a relation that allows one to extract the properties of gauged Q-balls (such as the radius, charge, and energy) from the more easily obtained properties of global Q-balls. These results provide a new guide to understanding gauged Q-balls as well as providing simple and accurate analytical characterization of the Q-ball properties.

We use a dispersion representation based on unitarity and analyticity to study the low energy ${\gamma }^{*}N\to \pi N$ process in the $S_{11}$ channel. Final state interactions among the $\pi N$ system are critical to this analysis. The left-hand part of the partial wave amplitude is imported from $\mathcal{O}(p^2)$ chiral perturbation theory result. On the right-hand part, the final state interaction is calculated through Omnès formula in $S$ wave. It is found that a good numerical fit can be achieved with only one subtraction parameter, and the eletroproduction experimental data of multipole amplitudes $E_{0+},S_{0+}$ in the energy region below $\mathrm{\Delta }(1232)$ are well described when the photon virtuality $Q^2\le 0.1{\mathrm{GeV}}^2$.

The $P$-wave charmonium decays $h_c\to \gamma {\eta }^{(\prime )}$ are revisited by taking into account relativistic corrections. The decay amplitudes are derived in the Bethe-Salpeter formalism, in which the involved one-loop integrals are evaluated analytically. Intriguingly, from both the quark-antiquark content and the gluonic content of ${\eta }^{(\prime )}$, the relativistic corrections make significant contributions to the decay rates of $h_c\to \gamma {\eta }^{(\prime )}$. By comparison with the leading-order contributions from the quark-antiquark content (one-loop level), the ones from the gluonic content (tree level) are also important, which is compatible with the conclusion obtained without relativistic corrections. Usually, for the $\eta$ production processes, the predicted branching ratios are sensitive to the angle of $\eta -{\eta }^{\prime }$ mixing. As an illustration, using the Feldmann-Kroll-Stech result about the mixing angle $\varphi =39.3°\pm 1.0°$ as input, we find that the predicted ratio $R_{h_c}=\mathcal{B}(h_c\to \gamma \eta )/\mathcal{B}(h_c\to \gamma {\eta }^{\prime })$ is much smaller than the experiment measurement, while, with $\varphi =33.5°\pm 0.9°$ extracted from the asymptotic limit of the ${\gamma }^{*}\gamma -{\eta }^{\prime }$ transition form factor, we obtain $R_{h_c}=30.3\%$, consistent with $R_{h_c}^{\exp }=(30.7\pm 11.3\pm 8.7)\%$. As a cross-check, the mixing angle $\varphi =33.8°\pm 2.5°$ is extracted by employing the ratio $R_{h_c}$, and a brief discussion on the difference in the determinations of $\varphi$ is given.

Correlations between the strange quark mass, strange quark condensate $⟨\overline{s}s⟩$, and the kaon partially conserved axial current (PCAC) relation are developed. The key dimensionless and renormalization-group invariant quantities in these correlations are the ratio of the strange to nonstrange quark mass $r_m=m_s/m_q$, the condensate ratio $r_c=⟨\overline{s}s⟩/⟨\overline{q}q⟩$, and the kaon PCAC deviation parameter $r_p=-m_s⟨\overline{s}s+\overline{q}q⟩/2f_K^2{m}_K^2$. The correlations define a self-consistent trajectory in the $\{r_m,r_c,r_p\}$ parameter space constraining strange quark parameters that can be used to assess the compatibility of different predictions of these parameters. Combining the constraint with Particle Data Group (PDG) values of $r_m$ results in $\{r_c,r_p\}$ constraint trajectories that are used to assess the self-consistency of various theoretical determinations of $\{r_c,r_p\}$. The most precise determinations of $r_c$ and $r_p$ are shown to be mutually consistent with the constraint trajectories and provide improved bounds on $r_p$. In general, the constraint trajectories combined with $r_c$ determinations tend to provide more accurate bounds on $r_p$ than direct determinations. The $\{r_c,r_p\}$ correlations provide a natural identification of a self-consistent set of strange quark mass and strange quark condensate parameters.

In this article, we introduce a new effective model for the Kantowski-Sachs spacetime in the context of loop quantum gravity, and we use it to evaluate departures from general relativity in the case of Schwarzschild black hole interior. The model is based on an effective Hamiltonian constructed via the regularized Thiemann identities in the $\overline{\mu }$-scheme. We show that, in contrast with the ${\mu }_o$-scheme studied in [Assanioussi et al., Phys. Rev. D 101, 026002 (2020)], the classical limit imposes certain alterations of Thiemann identities as well as restrictions on the choice of regulators. Once we define the Hamiltonian, we derive the equations of motion for the relevant variables and proceed with the solving using numerical methods, focusing on a specific choice of $\overline{\mu }$. We establish that for a Schwarzschild black hole interior, the effective dynamics leads to a resolution of the classical singularity and the emergence of an antitrapped region bounded by a second Killing horizon. We then perform a comparison of the dynamical trajectories and their properties obtained in the new model and some models present in the literature. We finally conclude with few comments on other choices of the regulators and their consequences.

We present a scalar-tensor theory of gravity on a torsion-free and metric compatible Lyra manifold. This is obtained by generalizing the concept of physical reference frame by considering a scale function defined over the manifold. The choice of a specific frame induces a local base, naturally nonholonomic, whose structure constants give rise to extra terms in the expression of the connection coefficients and in the expression for the covariant derivative. In the Lyra manifold, transformations between reference frames involving both coordinates and scale change the transformation law of tensor fields, when compared to those of the Riemann manifold. From a direct generalization of the Einstein-Hilbert minimal action coupled with a matter term, it was possible to build a Lyra invariant action, which gives rise to the associated Lyra scalar-tensor theory of gravity (LyST), with field equations for $g_{\mu \nu }$ and $\varphi$. These equations have a well-defined Newtonian limit, from which it can be seen that both metric and scale play a role in the description gravitational interaction. We present a spherically symmetric solution for the LyST gravity field equations. It dependent on two parameters $m$ and $r_L$, whose physical meaning is carefully investigated. We highlight the properties of LyST spherically symmetric line element and compare it to Schwarzchild solution.