Moduli spaces—finite-dimensional, collective coordinate manifolds—for kinks and antikinks in ${\varphi }^4$ theory and sine-Gordon theory are reconsidered. The field theory Lagrangian restricted to moduli space defines a reduced Lagrangian, combining a potential with a kinetic term that can be interpreted as a Riemannian metric on moduli space. Moduli spaces should be metrically complete, or have an infinite potential on their boundary. Examples are constructed for both kink-antikink and kink-antikink-kink configurations. The naive position coordinates of the kinks and antikinks sometimes need to be extended from real to imaginary values, although the field remains real. The previously discussed null-vector problem for the shape modes of ${\varphi }^4$ kinks is resolved by a better coordinate choice. In sine-Gordon theory, moduli spaces can be constructed using exact solutions at the critical energy separating scattering and breather (or wobble) solutions; here, energy conservation relates the metric and potential. The reduced dynamics on these moduli spaces accurately reproduces properties of the exact solutions over a range of energies.

We study quantum fields on spacetimes having a bifurcate Killing horizon by allowing the possibility that left and right (ingoing and outgoing) modes have different temperatures. An example of such a state is the Unruh vacuum in a black hole background, in which ingoing modes are in the zero temperature state, while the outgoing ones are at the Hawking temperature. We construct the corresponding Wightman functions and study their properties with arbitrary and different temperatures for both types of movers. We consider, in particular, the Rindler for both massless and massive fields, the static de Sitter, and Schwarzschild black hole backgrounds for massive fields. We find that in all three cases, when any of the temperatures are different from the canonical one (Unruh, Hawking, and Gibbons-Hawking, correspondingly) the correlation functions have extra singularities at the horizon.

We find the electric field of a point charge in the presence of a higher-dimensional black hole. As the charge is lowered to the horizon, all higher multipole moments go to zero, and only the Coulomb field remains.

Astrophysical black holes are ideal laboratories for testing Einstein’s theory of general relativity in the strong field regime. In this manuscript, we present an analysis of $Suzaku$ and $NuSTAR$ spectra of the black hole binary Cygnus X-1 using relxill_nk. Unlike our previous study on Cygnus X-1 with $NuSTAR$ data, here we are able to constrain the Johannsen deformation parameter ${\alpha }_{13}$. However, despite the high energy resolution near the iron line provided by $Suzaku$, our constraints on the Kerr metric from Cygnus X-1 are not very stringent in comparison with those that have been obtained from other sources, confirming that Cygnus X-1 is quite a complicated source.

The most statistically significant hints for new physics in the flavor sector are discrepancies between theory and experiment in $B$ decays to lepton pairs ($b\to s{\ell }^{+}{\ell }^{-}$) and a deficit in the unitarity constraints to the 1st row of the Cabibbo-Kobayashi-Maskawa matrix (the Cabibbo angle anomaly). We propose that these anomalies can be reconciled by a simplified model with massive gauge bosons transforming in the adjoint representation of $SU(2{)}_L$. After calculating the impact of this model on $B$ decays, observables testing charged current lepton flavor universality (LFU), electro-weak precision observables and LHC searches we perform a global fit to all available data. We find that our model can provide a consistent common explanation of both anomalies and that the fit to the data is more than $7\sigma$ better than the fit of the Standard Model. The model also predicts interesting correlations between LFU violation in the charged current and $b\to s{\ell }^{+}{\ell }^{-}$ data which can be tested experimentally in the near future.

We propose a theory of chiral fermion dark matter (DM) with an isospin-$3/2$ fermion of a dark sector $SU(2{)}_D$ gauge symmetry, which is arguably the simplest chiral theory. An isospin-3 scalar breaks $SU(2{)}_D$ down to a discrete non-Abelian group $T^{\prime }$ and generates the DM mass. The $SU(2{)}_D$ gauge symmetry protects the DM mass and guarantees its stability. We derive consistency conditions for the theory and study its DM phenomenology. In some regions of parameters of the theory a two-component DM scenario is realized, consisting of a fermion and a boson, with the boson being the lightest $T^{\prime }$ nonsinglet field. In the case of single-component fermionic DM, we find that internal consistency of the theory, perturbativity arguments, and the observed relic abundance limit the DM mass to be less than 280 GeV, except when $s$-channel resonance regions are open for annihilation. For a significant part of the parameter space, the theory can be tested in DM direct-detection signals at the LZ and XENONnT experiments.

Electromagnetic form factors of hyperons ($\mathrm{\Lambda }$, $\mathrm{\Sigma }$, $\mathrm{\Xi }$) in the timelike region, accessible in the reaction $e^{+}{e}^{-}\to \overline{Y}Y$, are studied. The focus is on energies close to the reaction thresholds, where the properties of these form factors are significantly influenced by the interaction in the final $\overline{Y}Y$ system. This interaction is taken into account in the calculation, utilizing $\overline{Y}Y$ potential models that have been constructed by the Jülich group for the analysis of data from the reaction $\overline{p}p\to \overline{Y}Y$ in the past. The enhancement of the effective form factor for energies close to the threshold, seen in experiments of $e^{+}{e}^{-}\to \overline{\mathrm{\Lambda }}\mathrm{\Lambda }$ and $e^{+}{e}^{-}\to {\overline{\mathrm{\Sigma }}}^0\mathrm{\Lambda }$, is reproduced. With regard to the reactions $e^{+}{e}^{-}\to {\overline{\mathrm{\Sigma }}}^{-}{\mathrm{\Sigma }}^{+}$, ${\overline{\mathrm{\Sigma }}}^0{\mathrm{\Sigma }}^0$, ${\overline{\mathrm{\Sigma }}}^{+}{\mathrm{\Sigma }}^{-}$ a delicate interplay between the three channels is observed in the results at low energies, caused by the $\overline{\mathrm{\Sigma }}\mathrm{\Sigma }$ interaction. Predictions for the electromagnetic form factors $G_M$ and $G_E$ in the timelike region are presented for the $\mathrm{\Lambda }$, $\mathrm{\Sigma }$, and $\mathrm{\Xi }$ hyperons.

We study the ${\tau }^{-}\to {\nu }_{\tau }{\pi }^{-}{\pi }^0{\ell }^{+}{\ell }^{-}$ ($\ell =e$, $\mu$) decays, which are $O({\alpha }^2)$ suppressed with respect to the dominant di-pion tau decay channel. Both the inner bremsstrahlung and the structure- (and model-) dependent contributions are considered. In the $\ell =e$ case, structure-dependent effects are $\mathcal{O}(1\%)$ in the decay rate, yielding a clean prediction of its branching ratio, $2.3\times {10}^{-5}$, measurable with BABAR or Belle(-II) data. For $\ell =\mu$, both contributions have a similar magnitude, and we get a branching fraction of $(1.6\pm 0.3)\times {10}^{-7}$, reachable by the end of Belle-II operation. These decays allow one to study the dynamics of strong interactions with simultaneous weak and electromagnetic probes; their knowledge will contribute to reducing backgrounds in lepton flavor and lepton number violating searches.

We study systematically the topological charge density and the chiral density correlations in the early stage of high energy nuclear collisions: the initial condition is given by the McLerran-Venugopalan model and the evolution of the gluon fields is studied via the Classical Yang-Mills equations up to proper time $\tau \approx 1\mathrm{fm}/\mathrm{c}$ for an SU(2) evolving Glasma. Topological charge is related to the gauge invariant $\mathit{E}·\mathit{B}$ where $\mathit{E}$ and $\mathit{B}$ denote the color-electric and color-magnetic fields, while the chiral density is produced via the chiral anomaly of Quantum Chromodynamics. We study how the correlation lengths are related to the collision energy, and how the correlated domains grow up with proper time in the transverse plane for a boost invariant longitudinal expansion. We estimate the correlation lengths of both quantities, that after a short transient results of the order of the typical energy scale of the model, namely the inverse of the saturation scale. We estimate the proper time for the formation of a steady state in which the production of the chiral density in the transverse plane per unit rapidity slows down, as well as the amount of chiral density that would be present at the switch time between the Classical Yang-Mills evolution and the relativistic transport or hydro for the quark-gluon plasma phase.

The full set of solutions of $f(T)$ gravity with the Minkowski metric is considered in this note. At the fourth order in perturbations around the trivial tetrad solution, a new mode is found explicitly. Its presence signals a strong coupling problem that transcends the Minkowski background and also suggests the ill-defined nature of cosmological solutions.

Recently it was discovered that null hypersurfaces can develop caustics outside the event horizon of super-entropic Kerr-AdS black holes, in contrast to the usual Kerr-AdS case. In this work we explore a few more examples of black hole spacetimes in which such exterior caustics can develop. If a closed null curve is present, e.g., in the case of Taub-NUT and the “transunital” Kerr-AdS spacetimes, then it coincides with a null hypersurface caustic (NHC) of a minimal separation parameter. Thus a spacetime on the verge of forming closed timelike curves could develop a caustic. Known examples of super-entropic black holes also have exterior NHC, although such spacetimes are free of closed null/timelike curves. Nevertheless the relationship between closed causal curves, NHC, and super entropy is not straightforward. This is best illustrated with the Bañados-Teitelboim-Zanelli (BTZ) black string, which for some choices of the warp factor in the extra dimension and the value of the charge, can be super-entropic. However, even those that are not super-entropic can admit NHC outside the horizon.

The method of topological renormalization in anti–de Sitter (AdS) gravity consists in adding to the action a topological term which renders it finite, defining at the same time a well-posed variational problem. Here, we use this prescription to work out the thermodynamics of asymptotically locally anti–de Sitter (AlAdS) spacetimes, focusing on the physical properties of the Misner strings of both the Taub-NUT-AdS and Taub-Bolt-AdS solutions. We compute the contribution of the Misner string to the entropy by treating on the same footing the AdS and AlAdS sectors. As topological renormalization is found to correctly account for the physical quantities in the parity-preserving sector of the theory, we then investigate the holographic consequences of adding also the Chern-Pontryagin topological invariant to the bulk action; in particular, we discuss the emergence of the parity-odd contribution in the boundary stress tensor.

We consider redshift drift in a general space-time as expressed in terms of physically interpretable multipole series. An important realization from the derived results is that redshift drift cannot in general be thought of as a direct probe of the average expansion rate of the Universe due to the presence of structure along the light beams from the astrophysical sources to the observer. We also predict the general presence of a dipolar and a quadrupolar offset in the detection of redshift drift for observers placed in locally anisotropic environments.

The relationship between the matrix element of a local operator and the Fourier transform of the associated form factor fails for systems such as the nucleon where its intrinsic size is of order its Compton wavelength. Although one can conceive of an intrinsic charge density distribution in the proton, there does not seem to be an unambiguous way to define, compute, or measure it precisely.

We perform an analysis within the Standard Model of $B^{0,+}\to K^{*0,+}{\mu }^{+}{\mu }^{-}$ decays in light of the recent measurements from the LHCb experiment, showing that new data strengthen the need for sizable hadronic contributions and correlations among them. We then extend our analysis to new physics via the Standard Model effective theory, and carry out a state-of-the-art fit of available $b\to s{\ell }^{+}{\ell }^{-}$ data, including possible hadronic contributions. We find the case of a fully left-handed operator standing out as the simplest scenario with a significance of almost $6\sigma$.

We compute mixed QCD-electroweak corrections to the fully differential production of an on-shell $W$ boson. Decays of $W$ bosons to lepton pairs are included in the leading order approximation. The required two-loop virtual corrections are computed analytically for arbitrary values of the electroweak gauge boson masses. Analytic results for integrated subtraction terms are obtained within a soft-collinear subtraction scheme optimized to accommodate the structural simplicity of infrared singularities of mixed QCD-electroweak contributions. Numerical results for mixed corrections to the fiducial cross section of $pp\to W^{+}\to l^{+}\nu$ and selected kinematic distributions in this process are presented.

For scalar perturbations of an extreme Reissner-Nordström black hole we show numerically that the Ori prefactor equals the Aretakis conserved charge. For a family of scalar or gravitational perturbations of an extreme Kerr black hole, whose members vary only in the radial location of the center of the initial packet, we demonstrate a linear relation of a generalized Ori prefactor—a certain expression obtained from the late-time expansion or the perturbation field at finite distances—and the Aretakis conserved charge. We infer that it can be established that there is an Aretakis conserved charge for scalar or gravitational perturbations of extreme Kerr black holes. This conclusion, in addition to the calculation of the Aretakis charge, can be made from measurements at a finite distance: Extreme Kerr black holes have gravitational hair that can be measured at finite distances and violates the uniqueness theorems. This gravitational hair can in principle be detected by gravitational-wave detectors.

We report measurements by the T2K experiment of the parameters ${\theta }_{23}$ and $\mathrm{\Delta }{m}_{32}^2$, which govern the disappearance of muon neutrinos and antineutrinos in the three-flavor PMNS neutrino oscillation model at T2K’s neutrino energy and propagation distance. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, muon-like events from each beam mode are used to measure these parameters separately for neutrino and antineutrino oscillations. Data taken from $1.49\times {10}^{21}$ protons on target (POT) in neutrino mode and $1.64\times {10}^{21}$ POT in antineutrino mode are used. The best-fit values obtained by T2K were ${\sin }^2({\theta }_{23})={0.51}_{-0.07}^{+0.06}({0.43}_{-0.05}^{+0.21})$ and $\mathrm{\Delta }{m}_{32}^2={2.47}_{-0.09}^{+0.08}({2.50}_{-0.13}^{+0.18})\times {10}^{-3}{\mathrm{eV}}^2/c^4$ for neutrinos (antineutrinos). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed. An analysis using an effective two-flavor neutrino oscillation model where the sine of the mixing angle is allowed to take nonphysical values larger than 1 is also performed to check the consistency of our data with the three-flavor model. Our data were found to be consistent with a physical value for the mixing angle.