A modified quantum kinetic equation which takes account of the noninertial features of rotating frame is proposed. The vector and axial-vector field components of the Wigner function for chiral fluids are worked out in a semiclassical scheme. It is demonstrated that the chiral currents and energy-momentum tensor computed by means of them are consistent with the hydrodynamical results. A new semiclassical covariant chiral transport equation is established by inspecting the equations satisfied by the chiral vector fields. It uniquely provides a new three-dimensional semiclassical chiral kinetic theory possessing a Coriolis force term. The particle number and current densities deduced from this transport equation satisfy the anomalous continuity equation and generate the magnetic and vortical effects correctly.

Consistency of trans-unification renormalization group (RG) evolution is used to discuss the domain of definition of the New Minimal Supersymmetric SO(10)GUT (NMSGUT). We define the 1-loop RGE $\beta$ functions, simplifying generic formulae using constraints of gauge invariance and superpotential structure. We also calculate the 2 loop contributions to the gauge coupling and gaugino mass and indicate how to get full 2 loop results for all couplings. Our method overcomes combinatorial barriers that frustrate computer algebra based attempts to calculate SO(10) $\beta$ functions involving large irreps. Use of the RGEs identifies a perturbative domain $Q<M_E$, where $M_E<M_{\text{Planck}}$ is the scale of emergence where the NMSGUT, with GUT compatible soft supersymmetry breaking terms emerges from the strong UV dynamics associated with the Landau poles in gauge and Yukawa couplings. Due to the strength of the RG flows the Landau poles for gauge and Yukawa couplings lie near a cutoff scale ${\mathrm{\Lambda }}_E$ for the perturbative dynamics of the NMSGUT which just above $M_E$. SO(10) RG flows into the IR are shown to facilitate small gaugino masses and generation of negative Non Universal Higgs masses squared needed by realistic NMSGUT fits of low energy data. Running the simple canonical theory emergent at $M_E$ through $M_X$ down to the electroweak scale enables tests of candidate scenarios such as supergravity based NMSGUT with canonical kinetic terms and NMSGUT based dynamical Yukawa unification.

We assess total-variation methods to denoise gravitational-wave signals in real noise conditions by injecting numerical-relativity waveforms from core-collapse supernovae and binary black hole mergers in data from the first observing run of Advanced LIGO. This work is an extension of our previous investigation in which only Gaussian noise was used. Since the quality of the results depends on the regularization parameter of the model, we perform a heuristic search for the value that produces the best results. We discuss various approaches for the selection of this parameter, based on the optimal, mean, or multiple values, and compare the results of the denoising upon these choices. Moreover, we also present a machine-learning-informed approach to obtain the Lagrange multiplier of the method through an automatic search. Our results provide further evidence that total-variation methods can be useful in the field of gravitational-wave astronomy as a tool to remove noise.

We perform dynamical and nonlinear numerical simulations to study critical phenomena in the gravitational collapse of massless scalar fields in the absence of spherical symmetry. We evolve axisymmetric sets of initial data and examine the effects of deviation from spherical symmetry. For small deviations we find values for the critical exponent and echoing period of the discretely self-similar critical solution that agree well with established values; moreover we find that such small deformations behave like damped oscillations whose damping coefficient and oscillation frequencies are consistent with those predicted in the linear perturbation calculations of Martín-García and Gundlach. However, we also find that the critical exponent and echoing period appear to decrease with increasing departure from sphericity and that, for sufficiently large departures from spherical symmetry, the deviations become unstable and grow, confirming earlier results by Choptuik et al. We find some evidence that these growing modes lead to a bifurcation, similar to those reported by Choptuik et al., with two centers of collapse forming on the symmetry axis above and below the origin. These findings suggest that nonlinear perturbations of the critical solution lead to changes in the effective values of the critical exponent, echoing period and damping coefficient and may even change the sign of the latter, so that perturbations that are stable in the linear regime can become unstable in the nonlinear regime.

Recently a new class of scalarized black holes in Einstein-Gauss-Bonnet (EGB) theories was discovered. What is special for these black hole solutions is that the scalarization is not due to the presence of matter, but it is induced by the curvature of spacetime itself. Moreover, more than one branch of scalarized solutions can bifurcate from the Schwarzschild branch, and these scalarized branches are characterized by the number of nodes of the scalar field. The next step is to consider the linear stability of these solutions, which is particularly important due to the fact that the Schwarzschild black holes lose stability at the first point of bifurcation. Therefore we here study in detail the radial perturbations of the scalarized EGB black holes. The results show that all branches with a nontrivial scalar field with one or more nodes are unstable. The stability of the solutions on the fundamental branch, whose scalar field has no radial nodes, depends on the particular choice of the coupling function between the scalar field and the Gauss-Bonnet invariant. We consider two particular cases based on the previous studies of the background solutions. If this coupling has the form used in [D. D. Doneva and S. S. Yazadjiev, Phys. Rev. Lett. 120, 131103 (2018)] the fundamental branch of solutions is stable, except for very small masses. In the case of a coupling function quadratic in the scalar field [H. O. Silva, J. Sakstein, L. Gualtieri, T. P. Sotiriou, and E. Berti, Phys. Rev. Lett. 120, 131104 (2018)], though, the whole fundamental branch is unstable.

We show that fragmentation of the inflaton into long-lived spatially localized oscillon configurations can lead to copious production of black holes. In simple inflation models primordial black holes of sublunar mass can form, and they can account for all of the dark matter. We also explore the possibility that solar-mass primordial black holes, particularly relevant for gravitational wave astronomy, are produced from the same mechanism.

Gravitational waves emitted by coalescing compact objects carry information about the spin of the individual bodies. However, with present detectors only the mass-weighted combination of the components of the spin along the orbital angular momentum can be measured accurately. This quantity, the effective spin ${\chi }_{\mathrm{eff}}$, is conserved up to at least the second post-Newtonian order. The measured distribution of ${\chi }_{\mathrm{eff}}$ values from a population of detected binaries, and in particular whether this distribution is symmetric about zero, encodes valuable information about the underlying compact-binary formation channels. In this paper we focus on two important complications of using the effective spin to study astrophysical population properties: (i) an astrophysical distribution for ${\chi }_{\mathrm{eff}}$ values which is symmetric does not necessarily lead to a symmetric distribution for the detected effective spin values, leading to a selection bias; and (ii) the posterior distribution of ${\chi }_{\mathrm{eff}}$ for individual events is asymmetric and it cannot usually be treated as a Gaussian. We find that the posterior distributions for ${\chi }_{\mathrm{eff}}$ systematically show fatter tails toward larger positive values, unless the total mass is large or the mass ratio $m_2/m_1$ is smaller than $\sim 1/2$. Finally we show that uncertainties in the measurement of ${\chi }_{\mathrm{eff}}$ are systematically larger when the true value is negative than when it is positive. All these factors can bias astrophysical inference about the population when we have more than $\sim 100$ events and should be taken into account when using gravitational-wave measurements to characterize astrophysical populations.

Astrophysical observations of spinning black holes, which span $5M_{\odot }\lesssim M_{\mathrm{BH}}\lesssim 5\times {10}^8{M}_{\odot }$, can be used to exclude the existence of certain massive bosons via the superradiance phenomenon. In this work, we explore for the first time how these measurements can be used to constrain properties of statistical distributions for the masses of multiple bosonic fields. Quite generally, our methodology excludes $N_{\mathrm{ax}}\gtrsim 30$ scalar fields with a range of mass distribution widths and central values spanning many orders of magnitude. We demonstrate this for the specific example of axions in string theory and M-theory, where the mass distributions in certain cases take universal forms. We place upper bounds on $N_{\mathrm{ax}}$ for certain scenarios of interest realized approximately as mass distributions in M-theory, including the QCD axion, grand unified theories, and fuzzy dark matter.

The dilepton production rate in a hot QCD medium is studied within an effective description of the medium in the presence of a magnetic field. This could be done by obtaining the one-loop self-energy of the photon due to the effective (quasi)quark loop at a finite temperature under an arbitrary external magnetic field while employing the real time formalism of thermal field theory. The effective quarks and gluons encode a hot QCD medium effective in terms of their respective effective fugacities. The magnetic field enters in the form of Landau level quantization, in the matter sector (quarks, antiquarks). The full Schwinger proper time propagator including all the Landau levels is considered for the quasiquarks while calculating the photon self-energy. The electromagnetic Debye screening (in terms of the self-energy) has been influenced by both the hot QCD medium effects and the magnetic field. Analogous results are also obtained from the semiclassical transport theory. The imaginary part of the photon self-energy function is obtained from the discontinuities of the self-energy across the unitary cuts that are also present at the zero magnetic field and the Landau cuts that are purely due to the magnetic field. The dilepton production rate is then obtained in terms of the product of electromagnetic spectral functions due to the quark loop and the lepton loop. The modifications of both the quarks/antiquarks as well as leptons in the presence of an arbitrary external magnetic field have been considered in the formalism. Significant enhancement of the low invariant mass dileptons due to the appearance of the Landau cuts in the electromagnetic spectral function at the finite external magnetic field has been observed. A substantial enhancement of the dilepton rate is also found when the equation of state effects are considered through the effective quarks/antiquraks.

We explore two-Higgs-doublet models with nonstandard flavor structures. In analogy to the four well-studied models with natural flavor conservation (type 1, type 2, lepton-specific, and flipped), we identify four models that preserve an approximate $U(2{)}^5$ flavor symmetry acting on the first two generations. In all four models, the couplings of the 125 GeV Higgs are modified in characteristic flavor nonuniversal ways. The heavy neutral and charged Higgs bosons show an interesting nonstandard phenomenology. We discuss their production and decay modes and identify the most sensitive search channels at the LHC. We study the effects on low energy flavor violating processes, finding relevant constraints from $B_d$ and $B_s$ meson oscillations and from the rare decay $B_s\to {\mu }^{+}{\mu }^{-}$. We also find that lepton flavor violating $B$ meson decays like $B_s\to \tau \mu$ and $B\to K^{(*)}\tau \mu$ might have branching ratios at an observable level.

We calculate the intrinsic quark spin contribution to the total proton spin using overlap valence quarks on three ensembles of $2+1$-flavor RBC/UKQCD domain-wall configurations with different lattice spacings. The lowest pion mass of the ensembles is around 171 MeV, which is close to the physical point. With overlap fermions and a topological charge derived from the overlap operator, we verify the anomalous Ward identity between nucleon states with momentum transfer. Both the connected and the disconnected insertions of the axial-vector current are calculated. For the disconnected-insertion part, the cluster-decomposition error reduction technique is utilized for the lattice with the largest volume and the error can be reduced by 10%–40%. Nonperturbative renormalization is carried out and the final results are all reported in the $\overline{\mathrm{MS}}$ scheme at 2 GeV. We determine the total quark spin contribution to the nucleon spin to be $\mathrm{\Delta }\mathrm{\Sigma }=0.405(25)(37)$, which is consistent with the recent global fitting result of experimental data. The isovector axial coupling we obtain in this study is $g_A^3=1.254(16)(30)$, which agrees well with the experimental value of 1.2723(23).

We study the realization of axion electrodynamics in QCD in the presence of a background magnetic field at temperatures high enough for the occurrence of topological charge transitions that are reflected in the presence of a $\theta$-vacuum term in the action. We show that in this system, the Maxwell equations contain two equal and opposite electric currents that are proportional to the time derivative of the axion field $\theta$. One of these currents comes directly from the Abelian chiral anomaly term in the action and can be interpreted as a polarization current due to the magnetoelectricity of the system with $CP$-broken symmetry. The other current is obtained from the regular tadpole diagrams and can be understood as produced by the medium chiral imbalance and the single spin projection of the quarks in the lowest Landau level. Since the two currents cancel out, the net electric charge separation along the magnetic field, a phenomenon known as the chiral magnetic effect, does not take place. Thus, if chirally imbalanced QCD is correctly represented by the model under consideration, then the chiral magnetic effect is absent. We discuss the similarities and differences with Weyl semimetals in a magnetic field.

We directly calculate spectral functions in the $O(N)$ model at finite temperature within the framework of the functional renormalization group. Special emphasis is put on a fully numerical framework involving four-dimensional regulators preserving Euclidean $O(4)$ and Minkowski Lorentz invariance, an important prerequisite for future applications. Pion and sigma meson spectral functions are calculated for a wide range of temperatures across the phase transition illustrating the applicability of the general framework for finite temperature applications. In addition, various aspects concerning the interplay between the Euclidean and real-time two-point function are discussed.

We derive equations of motion for the reduced density matrix of a heavy quarkonium in contact with a quark-gluon plasma in thermal equilibrium. These equations allow in particular a proper treatment of the regime when the temperature of the plasma is comparable to the binding energy of the quarkonium. These equations are used to study how the quarkonium approaches equilibrium with the plasma, and we discuss the corresponding entropy increase, or free energy decrease, depending on the temperature regime. The effect of collisions can be accounted for by the generalization of the imaginary potential introduced in previous studies, and from which collision rates are derived. An important outcome of the present analysis is that this imaginary potential has a sizable dependence on the energy of the relevant transitions.

The standard model does not provide an explanation of the observed alignment of quark flavors i.e. why are the up and down quarks approximately aligned in their weak interactions according to their masses? We suggest a resolution of this puzzle using a combination of left-right and Peccei-Quinn (PQ) symmetry. The quark mixings in this model vanish at the tree level and arise out of one loop radiative corrections which explain their smallness. The lepton mixings, on the other hand, appear at the tree level and are therefore larger. We show that all fermion masses and mixings can be fitted with a reasonable choice of parameters. The neutrino mass fit using seesaw mechanism requires the right-handed $W_R$ mass bigger than 18 TeV. Due to the presence of PQ symmetry, this model clearly provides a solution to the strong $CP$ problem.

We have searched for the lepton-flavor-violating decay $B^0\to K^{*0}{\mu }^{\pm }{e}^{\mp }$ using a data sample of $711{\mathrm{fb}}^{-1}$ that contains $772\times {10}^6$ $B\overline{B}$ pairs. The data were collected near the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. No signals were observed, and we set 90% confidence level upper limits on the branching fractions of $\mathcal{B}(B^0\to K^{*0}{\mu }^{+}{e}^{-})<1.2\times {10}^{-7}$, $\mathcal{B}(B^0\to K^{*0}{\mu }^{-}{e}^{+})<1.6\times {10}^{-7}$, and, for both decays combined, $\mathcal{B}(B^0\to K^{*0}{\mu }^{\pm }{e}^{\mp })<1.8\times {10}^{-7}$. These are the most stringent limits on these decays to date.

We discuss scattering in a conformal field theory (CFT) via the conformal partial-wave analysis and the Regge limit. The focus of this paper is on understanding an operator product expansion (OPE) with Minkowski conformal blocks. Starting with a t-channel OPE, it leads to an expansion for an s-channel scattering amplitude in terms of t-channel exchanges. By contrasting with Euclidean conformal blocks we see a precise relationship between conformal blocks in the two limits without preforming an explicit analytic continuation. We discuss a generic feature for a CFT correlation function having singular $F^{(M)}(u,v)\sim u^{-\delta }$, $\delta >0$, in the limit $u\to 0$ and $v\to 1$. Here, $\delta =({\ell }_{\mathrm{eff}}-1)/2$, with ${\ell }_{\mathrm{eff}}$ serving as an effective spin and it can be determined through an OPE. In particular, it is bounded from above, ${\ell }_{\mathrm{eff}}\le 2$, for all CFTs with a gravity dual, and it can be associated with string modes interpolating the graviton in AdS. This singularity is historically referred to as the Pomeron. This bound is nearly saturated by SYK-like effective $d=1$ CFT, and its stringy and thermal corrections have piqued current interests. Our analysis has been facilitated by dealing with Wightman functions. We provide a direct treatment in diagonalizing dynamical equations via harmonic analysis over physical scattering regions. As an example these methods are applied to the SYK model.

We contrast the dynamics of the Hořava theory with anisotropic Weyl symmetry with the case where this symmetry is explicitly broken, which is called the kinetic-conformal Hořava theory. To do so, we perform the canonical formulation of the anisotropic conformal theory at the classical level with a general conformal potential. Both theories have the generator of the anisotropic Weyl transformations as a constraint, but it changes from first to second class when the Weyl symmetry is broken. The FDiff-covariant vector $a_i={\partial }_i\ln N$ plays the role of gauge connection for the anisotropic Weyl transformations. A Lagrange multiplier also plays the role of gauge connection since it is the time component. The anisotropic conformal theory propagates the same number of degrees of freedom as the kinetic-conformal theory, which in turn are the same as general relativity. This similarity is due to the exchange of a second-class constraint in the kinetic-conformal case by a gauge symmetry in the anisotropic conformal case. An exception occurs if the conformal potential does not depend on the lapse function $N$, as is the case of the so-called $(\text{Cotton}{)}^2$ potential, in which one of the physical modes becomes odd. We develop in detail two explicit anisotropic conformal models. One of them depends on $N$, whereas the other one is the $(\text{Cotton}{)}^2$ model. We also study conformally flat solutions in the anisotropic conformal and kinetic-conformal theories, defining as conformally flat the spatial metric, but leaving for $N$ a form different from the one dictated by the anisotropic Weyl transformations. We find that in both theories, these configurations have vanishing canonical momentum, and they are critical points of the potential. In the kinetic-conformal theory, we explicitly find an exact, nontrivial, conformally flat solution.

To find the origin of chaos near the black hole horizon in string-theoretic $\mathrm{AdS}/\mathrm{CFT}$ correspondence, we perform a chaos analysis of a suspended string in AdS black hole backgrounds. It has a definite CFT interpretation: chaos of Wilson loops or, in other words, sensitive time evolution of a quark-antiquark force in thermal gauge theories. Our nonlinear numerical simulation of the suspended Nambu-Goto string shows chaos, which would be absent in a pure AdS background. The calculated Lyapunov exponent $\lambda$ satisfies the universal bound $\lambda \le 2\pi T_{\mathrm{H}}$ for the Hawking temperature $T_{\mathrm{H}}$. We also analyze a toy model of a rectangular string probing the horizon and show that it contains a universal saddle characterized by the surface gravity $2\pi T_{\mathrm{H}}$. Our work demonstrates that the black hole horizon is the origin of the chaos, and suggests a close interplay between chaos and quark deconfinement.

We explore the important fundamental question of how quantum information is localized in quantum gravity, in a perturbative approach. Familiar descriptions of localization of information, such as via tensor factorization of the Hilbert space or a net of commuting subalgebras of operators, conflict with basic gravitational properties—specifically gauge invariance—already at leading order in perturbation theory. However, previous work found that information can be classically localized in a region in a way such that measurements, including those of the gravitational field, outside the region are insensitive to that information and only measure total Poincaré charges. This paper shows that, working to leading order in the gravitational coupling, a similar quantum result holds, leading to a definition of a “gravitational splitting” on the Hilbert space for gravity. Such localization of information also argues against a role for “soft hair” in resolving the information problem for black holes. This basic mathematical structure plausibly plays a foundational role in the quantum description of gravity.