In this paper we present an Abelian Higgs model in which the scalar field is nonminimally coupled with the Maxwell field. This model gives rise to the Bopp-Podolsky theory in the following way: for certain values of the coupling constants, when the $U(1)$ symmetry is kept explicit, the resulting theory is the usual Maxwell theory for electromagnetism. On the other hand, in the hidden symmetry phase, the emerging theory for the electromagnetism is the Bopp-Podolsky theory.

We study the application of SU(3) gauge field smoothing methods to $Z(3)$-projected center-vortex gauge fields. Due to the proportionality of the vortex links to the identity, naive applications of these methods are either ineffectual or limited in scope, containing subtle issues that are not obviously manifest. To overcome these issues, we introduce centrifuge preconditioning, a novel method applied prior to smoothing that rotates the links away from the center while preserving the fundamental structure of the vortex field. Additionally, the concept of vortex-preserved annealed smoothing is formulated to ensure the smoothing procedure maintains the underlying vortex structure. The application of these new methods in the context of annealed smoothing applied to vortex fields is shown to successfully achieve the desired smoothness condition required for the study of more advanced operators.

The properties of QED-vacuum polarization, caused by the supercritical external Coulomb source with charge $Z$ and size $R$, are explored in an essentially nonperturbative approach with emphasis on the vacuum energy ${\mathcal{E}}_{\mathrm{VP}}$ (where VP stands for vacuum polarization.) It is shown that in the supercritical region ${\mathcal{E}}_{\mathrm{VP}}$ turns out to be a decreasing function of the Coulomb charge, resulting in decay into the negative range as $\sim -Z^4/R$. Moreover, it is indeed the decline of ${\mathcal{E}}_{\mathrm{VP}}$, which provides the required energy for (presumably possible) positron emission. Found this way, properties of the resonance decay are in agreement with those achieved by other methods. The additional problems of spontaneous emission, caused by lepton number, are also discussed.

Recently, many geometric aspects of $\mathcal{N}$-extended anti–de Sitter supergravity in chiral variables have been encountered and clarified. In particular, if the theory is supposed to be invariant under supersymmetry transformations also on boundaries, the boundary term has to be the action of an $\mathrm{OSp}(\mathcal{N}|2{)}_{\mathbb{C}}$ super Chern-Simons theory, and particular boundary conditions must be met. Based on this, we propose a way to calculate an entropy $S$ for surfaces, presumably including black hole horizons, in the supersymmetric version of loop quantum gravity for the minimal case $\mathcal{N}=1$. It proceeds in analogy to the nonsupersymmetric theory, by calculating dimensions of quantum state spaces of the super Chern-Simons theory with punctures, for a fixed quantum (super) area of the surface. We find $S=a_H/4$ for large areas and determine the subleading correction. Because of the noncompactness of $\mathrm{OSp}(1|2{)}_{\mathbb{C}}$ and the corresponding difficulties with the Chern-Simons quantum theory, we use analytic continuation from the Verlinde formula for a compact real form, $\mathrm{UOSp}(1|2)$, in analogy to work by Noui et al. This also entails studying some properties of $\mathrm{OSp}(1|2{)}_{\mathbb{C}}$ representations that we have not found elsewhere in the literature.

The near horizon aspects (and beyond) of a black hole metric, which belongs to a large class of static spherically symmetric black holes, is considered here. It has been realized recently that an atom falling into a black hole leads to the generation of acceleration radiation through virtual transitions. In recent studies it has been argued that this acceleration radiation can be understood from the near horizon physics of the black hole. The near horizon approximation leads to conformal symmetry in the problem. We go beyond the near horizon approximation in our analysis. This breaks the conformal symmetry associated with the near horizon physics of the black hole geometry. We observe that even without the consideration of the conformal symmetry, the modified equivalence relation holds. Further, our analysis reveals that the probability of virtual transition retains its Planck-like form with the amplitude getting modified due to the beyond near horizon approximation. For the next part of our analysis, we have observed the horizon brightened acceleration radiation entropy (HBAR) for a Garfinkle-Horowitz-Strominger black hole. We observe that the HBAR entropy misses out on quantum gravitylike corrections while considering the conformal case. However, such corrections emerge when the conformal symmetry gets broken in the beyond near horizon analysis.

We establish the correspondence between the classical and quantum butterfly effects in nonlinear vector mechanics with the broken $O(N)$ symmetry. On one hand, we analytically calculate the out-of-time-ordered correlation functions and the quantum Lyapunov exponent using the augmented Schwinger-Keldysh technique in the large-$N$ limit. On the other hand, we numerically estimate the classical Lyapunov exponent in the high-temperature limit, where the classical chaotic behavior emerges. In both cases, Lyapunov exponents approximately coincide and scale as $\kappa \approx 1.3\sqrt[4]{\lambda T}/N$ with temperature $T$, number of degrees of freedom $N$, and coupling constant $\lambda$.

The gravitational wave signal from a binary neutron star merger carries the imprint of the deformability properties of the coalescing bodies, and then of the equation of state of neutron stars. In current models of the waveforms emitted in these events, the contribution of tidal deformation is encoded in a set of parameters, the tidal Love numbers. More refined models include tidal-rotation couplings, described by an additional set of parameters, the rotational tidal Love numbers, which appear in the waveform at 6.5 post-Newtonian order. For neutron stars with spins as large as $\sim 0.1$, we show that neglecting tidal-rotation couplings may lead to a significant error in the parameter estimation by third-generation gravitational wave detectors. By performing a Fisher matrix analysis we assess the measurability of rotational tidal Love numbers, showing that their contribution in the waveform could be measured by third-generation detectors. Our results suggest that current models of tidal deformation in late inspiral should be improved in order to avoid waveform systematics and extract reliable information from gravitational wave signals observed by next generation detectors.

Chameleon $f(R)$ gravity is equivalent to a class of scalar-tensor theories of gravity with the chameleon screening mechanism allowing the theory to satisfy local tests of gravity. Within the framework of chameleon $f(R)$, we study the impact of the chameleon mechanism on the orbital evolution of binary pulsars, and calculate in detail the post-Keplerian (PK) effects (periastron advance, Einstein delay, Shapiro delay, orbital period decay and eccentricity decay) of binary orbit. The differences in PK effects between general relativity (GR) and chameleon $f(R)$ are elegantly quantified by a combination of star’s compactness and theory parameter. We use the mass-radius relation to break the degeneracy between these two parameters, thus allowing us to constrain the theory. We simulate the temporal evolution of the orbital period and eccentricity of neutron star (NS)-white dwarf (WD) binaries, and the results indicate that the orbital evolution is typically faster than in GR due to the emission of dipole radiation in chameleon $f(R)$. We use the observables of PK parameters from the three NS-WD binary pulsars to place constraints on chameleon $f(R)$ and possible deviations from GR by performing Monte-Carlo simulations. We find that PSR $\mathrm{J}1738+0333$ is the most constraining test of chameleon $f(R)$ in these systems. Our results show no solid evidence of the existence of helicity-0 or helicity-1 polarization states inducing dipole radiation, exclude significant strong-field deviations and confirm that GR is still valid for strong-field asymmetric systems.

The dynamics of both the preinflationary and the preheating epochs for a model consisting of a Higgs inflaton plus an additional auxiliary field are studied in full General Relativity. The minimally coupled auxiliary field allows for parametric-type resonances that successfully transfer energy from the inflaton condensate to particle excitations in both fields. Depending on the interaction strengths of the fields, the broad resonance periods lead to structure formation consisting of large under/overdensities, and possibly the formation of compact objects. Moreover, when confronting the same model to multifield inhomogeneous preinflation, the onset of inflation is shown to be a robust outcome. At relatively large Higgs values, the nonminimal coupling acts as a stabilizer, protecting the dynamics of the inflaton, and significantly reducing the impact of perturbations in other fields and matter sectors. These investigations further confirm the robustness of Higgs inflation to multifield inhomogeneous initial conditions, while putting in evidence the formation of complex structures during the reheating.

Seconds-long numerical-relativity simulations for black hole–neutron star mergers are performed for the first time to obtain a self-consistent picture of the merger and post-merger evolution processes. To investigate the case that tidal disruption takes place, we choose the initial mass of the black hole to be $5.4M_{\odot }$ or $8.1M_{\odot }$ with a dimensionless spin of 0.75. The neutron-star mass is fixed to be $1.35M_{\odot }$. We find that after the tidal disruption, dynamical mass ejection takes place over $\lesssim 10\mathrm{ms}$, together with the formation of a massive accretion disk. Subsequently, the magnetic field in the disk is amplified by the magnetic winding and magnetorotational instability, establishing a turbulent state and inducing angular momentum transport. The post-merger mass ejection by the magnetically induced viscous effect sets in at $\sim 300–500\mathrm{ms}$ after the tidal disruption, at which the neutrino luminosity drops below $\sim {10}^{51.5}\mathrm{erg}/\mathrm{s}$, and continues for several hundred ms. A magnetosphere near the rotational axis of the black hole is developed after the matter and magnetic flux fall into the black hole from the accretion disk, and high-intensity Poynting flux generation sets in at a few hundred ms after the tidal disruption. The intensity of the Poynting flux becomes low after the significant post-merger mass ejection, because the opening angle of the magnetosphere increases. The lifetime of the stage with the strong Poynting flux is 1–2 s, which agrees with the typical duration of short-hard gamma-ray bursts.

We investigate the dynamical spin polarization of a massless electron probing an electron plasma in locally thermal equilibrium via the Moller scattering from the quantum kinetic theory. We derive an axial kinetic equation delineating the dynamical spin evolution in the presence of the collision term with quantum corrections up to $\mathcal{O}(\hslash )$ and the leading-logarithmic order in coupling by using the hard-thermal-loop approximation, from which we extract the spin-polarization rate induced by the spacetime gradients of the medium. When the electron probe approaches local equilibrium, we further simplify the collision term into a relaxation-time expression. Our kinetic equation may be implemented in the future numerical simulations for dynamical spin polarization.

We propose a novel model for lepton flavor and dark matter based on the $SU(2{)}_D$ gauge symmetry and vectorlike leptons in its fundamental representations. We introduce a dark $SU(2{)}_D$ Higgs doublet and a Higgs bidoublet for the mass mixing between the vectorlike lepton and the lepton. As a result, the seesaw lepton masses are generated and there are sizable one-loop contributions to the muon $g-2$ via the $SU(2{)}_D$ gauge bosons and the relatively heavy vectorlike lepton, as indicated in Fermilab E989. The tree-level mass mixing between the $Z$ boson and the isospin-neutral gauge boson of $SU(2{)}_D$ in our model accounts for the shift in the $W$ boson mass, being consistent with Tevatron CDFII. Finally, we show that the isospin charged gauge boson of $SU(2{)}_D$ becomes a plausible candidate for dark matter with a small mass splitting tied up to the modified $W$ boson mass, and there is a viable parameter space where the favored corrections to the muon $g-2$ and the $W$ boson mass and the dark matter constraints are simultaneously fulfilled.

We propose a novel way of probing high-scale Dirac leptogenesis, a viable alternative to the canonical leptogenesis scenario where the total lepton number is conserved, keeping light standard model neutrinos purely Dirac. The simplest possible seesaw mechanism for generating light Dirac neutrinos involves heavy singlet Dirac fermions and a singlet scalar. In addition to unbroken global lepton number, a discrete $Z_2$ symmetry is imposed to forbid direct coupling between right and left chiral parts of light Dirac neutrinos. Generating light Dirac neutrino mass requires the singlet scalar to acquire a vacuum expectation value (VEV) that also breaks the $Z_2$ symmetry, leading to the formation of domain walls in the early Universe. These walls, if made unstable by introducing a soft $Z_2$-breaking term, generate gravitational waves (GWs) with a spectrum characterized by the wall tension or the singlet VEV, and the soft symmetry breaking scale. The scale of leptogenesis depends on the $Z_2$-breaking singlet VEV, which is also responsible for the tension of the domain wall, affecting the amplitude of GWs produced from the collapsing walls. We find that most of the near-future GW observatories will be able to probe Dirac leptogenesis scales all the way up to ${10}^{11}\mathrm{GeV}$.

We present a lattice calculation of the charged/neutral pion mass difference $M_{{\pi }^{+}}-M_{{\pi }^0}$ at order $\mathcal{O}({\alpha }_{\mathrm{em}})$ using the gauge configurations produced by the Extended Twisted Mass Collaboration with $N_f=2+1+1$ dynamical quark flavors at three values of the lattice spacing ($a\simeq 0.062,0.082,0.089\mathrm{fm}$) and pion masses in the range $M_{\pi }\simeq 250–500\mathrm{MeV}$. We employ the RM123 method and expand the path integral around the isospin symmetric point at leading order in the electromagnetic coupling ${\alpha }_{\mathrm{em}}$. Making use of the recently proposed rotated twisted-mass scheme, we evaluate the full $\mathcal{O}({\alpha }_{\mathrm{em}})$ contribution, with the inclusion of the disconnected diagram. At the physical point, after performing the continuum and infinite volume extrapolation, we obtain the value $M_{{\pi }^{+}}-M_{{\pi }^0}=4.622(95)\mathrm{MeV}$ which is in good agreement with the experimental result $[M_{{\pi }^{+}}-M_{{\pi }^0}{]}^{\exp }=4.5936(5)\mathrm{MeV}$.

We propose UV complete (partially) composite Higgs models with compositeness scale up to the Planck scale assisted by a novel mechanism. This mechanism is based on softly breaking a global ${\mathbb{Z}}_2$ symmetry by technically natural small vacuum misalignment, dynamically triggering the electroweak symmetry breaking and Standard Model fermion mass generation. This mechanism can be present in various models based on vacuum misalignment. For concreteness, we demonstrate it in a minimal partially composite two-Higgs boson scheme, where the Higgs boson is a mixture of a composite and an elementary state, transforming odd under a ${\mathbb{Z}}_2$ symmetry. For this concrete model example, all dimensionful fundamental parameters are approximately $\mathcal{O}({10}^{18})\mathrm{GeV}$. We study the vacuum stability of this model by investigating the renormalization group running of the quartic coupling of the Higgs boson. Furthermore, the parameter space can already be searched by gravitational waves from a confinement-induced phase transition. Finally, the mass and mixing of the neutrinos may be naturally generated via loops of a second Higgs doublet transforming even under the ${\mathbb{Z}}_2$ symmetry, which may be challenged by lattice calculations and a more accurate measurement of the top mass.

We search for a new gauge boson $Z^{\prime }$ that couples only to heavy leptons and their corresponding neutrinos in the process $e^{+}{e}^{-}\to Z^{\prime }(\to {\mu }^{+}{\mu }^{-}){\mu }^{+}{\mu }^{-}$, using a $643{\mathrm{fb}}^{-1}$ data sample collected by the Belle experiment at or near the $\mathrm{\Upsilon }(1S,2S,3S,4S,5S)$ resonances at the KEKB collider. While previous searches for $Z^{\prime }$ performed a data-based estimation of the initial state radiation effect, our search for the $Z^{\prime }$ is the first to include effects due to initial state radiation in the signal simulated samples that were used in estimating the detection efficiency. No signal is observed in the $Z^{\prime }$ mass range of $0.212–10\mathrm{GeV}/c^2$, and we set an upper limit on the coupling strength, $g^{\prime }$, constraining the possible $Z^{\prime }$ contribution to the anomalous magnetic dipole moment of the muon.

In this work, we explore the effects of a quantum quench on the entanglement measures of a two-body coupled oscillator system having quartic interaction. We use the invariant operator method, under a perturbative framework, for computing the ground state of this system. We give the analytical expressions for the total and reduced density matrix of the system having non-Gaussian, quartic interaction terms. Using this reduced density matrix, we show the analytical calculation of two entanglement measures viz., Von Neumann entanglement entropy using replica trick and Renyi entanglement entropy. Further, we give a numerical estimate of these entanglement measures with respect to the dimensionless parameter $(t/\delta t)$ and show its behavior in the three regimes, i.e., late time behavior, around the quench point and the early time behavior. We comment on the variation of these entanglement measures for different orders of coupling strength. The variation of Renyi entropy of different orders has also been discussed.

We present a reanalysis of GW151226, the second binary black hole merger discovered by the LIGO–Virgo Collaboration. Previous analysis showed that the best-fit waveform for this event corresponded to the merger of a $\sim 14M_{\odot }$ black hole with a $\sim 7.5M_{\odot }$ companion, and the posterior distribution in mass ratio ($q\le 1$) is rather flat. In this work, we perform parameter estimation using a waveform model that includes the effects of orbital precession and higher-order radiative multipole modes, and we find that the source parameters of GW151226 shift toward the low $q$ and high effective spin (${\chi }_{\mathrm{eff}}$) region and that $q$ is better measured. The new solution has a log likelihood roughly two points higher than when either higher multipoles or orbital precession is neglected and can alter the astrophysical interpretation of GW151226. Additionally, we find it useful to use a flat-in-${\chi }_{\mathrm{eff}}$ prior, which does not penalize the large $|{\chi }_{\mathrm{eff}}|$ region, in order to uncover the higher likelihood region for GW151226. Our solution has several interesting properties: (a) the secondary black hole mass is close to the upper limit of the hypothesized lower mass gap of astrophysical black hole population; and (b) orbital precession is driven by the primary black hole spin, which has a dimensionless magnitude as large as $\sim 0.85$ and is tilted away from the orbital angular momentum at an angle of $\sim 57°$. Since GW151226 is a relatively weak signal, an unambiguous claim of the detection of these effects in the signal cannot be made.

We formulate axion-electrodynamics and magnetohydrodynamics (MHD) in the cosmological context assuming weak gravity. The two formulations are made for a general scalar field with general $f(\varphi )$-coupling, and an axion as a massive scalar field with ${\varphi }^2$-coupling, with the helical electromagnetic field. The $\alpha$-dynamo term appears naturally from the helical coupling in the MHD formulation. In the presence of the electromagnetic coupling, however, the Schrödinger and hydrodynamic formulations of the coherently oscillating axion are not available for the conventional $\varphi$ coupling; instead, ${\varphi }^2$ coupling allows successful formulations preserving the dark matter nature of the axion to nonlinear order. In the MHD formulation, direct couplings between the scalar and electromagnetic fields appear only for nonideal MHD. We study gravitational and magnetic instabilities of the scalar field and axion MHDs.