We perform a set of 36 nonprecessing black-hole binary simulations with spins either aligned or counteraligned with the orbital angular momentum in order to model the final mass, spin, and recoil of the merged black hole as a function of the individual black-hole spin magnitudes and the mass ratio of the progenitors. We find that the maximum recoil for these configurations is $V_{\max }=526\pm 23\mathrm{km}{\mathrm{s}}^{-1}$, which occurs when the progenitor spins are maximal, the mass ratio is $q_{\max }=m_1/m_2=0.623\pm 0.038$, the smaller black-hole spin is aligned with the orbital angular momentum, and the larger black-hole spin is counteraligned (${\alpha }_1=-{\alpha }_2=1$). This maximum recoil is about $80\mathrm{km}{\mathrm{s}}^{-1}$ larger than previous estimates, but most importantly, because the maximum occurs for smaller mass ratios, the probability for a merging binary to recoil faster than $400\mathrm{km}{\mathrm{s}}^{-1}$ can be as large as 17%, while the probability for recoils faster than $250\mathrm{km}{\mathrm{s}}^{-1}$ can be as large as 45% when the spins are aligned or counteraligned by accretion. We provide explicit phenomenological formulas for the final mass, spin, and recoil as a function of the individual black-hole spins and the mass difference between the two black holes. Here we include terms up through fourth order in the initial spins and mass difference and find excellent agreement (within a few percent) with independent results available in the literature. The maximum radiated energy is $E_{\text{rad}}/m\approx 11.3\%$ and final spin ${\alpha }_{\text{rem}}^{\max }\approx 0.952$ for equal-mass, aligned, maximally spinning binaries.

We study the quantum dynamics of a supersymmetric squashed three-sphere by dimensionally reducing (to one timelike dimension) the action of $D=4$ simple supergravity for a $SU(2)$-homogeneous (Bianchi IX) cosmological model. The quantization of the homogeneous gravitino field leads to a 64-dimensional fermionic Hilbert space. After imposition of the diffeomorphism constraints, the wave function of the Universe becomes a 64-component spinor of spin(8,4) depending on the three squashing parameters, which satisfies Dirac-like, and Klein-Gordon-like, wave equations describing the propagation of a “quantum spinning particle” reflecting off spin-dependent potential walls. The algebra of the supersymmetry constraints and of the Hamiltonian one is found to close. One finds that the quantum Hamiltonian is built from operators that generate a 64-dimensional representation of the (infinite-dimensional) maximally compact subalgebra of the rank-3 hyperbolic Kac-Moody algebra $A{E}_3$. The (quartic-in-fermions) squared-mass term ${\widehat{\mu }}^2$ entering the Klein-Gordon-like equation has several remarkable properties: (i) it commutes with all the other (Kac-Moody-related) building blocks of the Hamiltonian; (ii) it is a quadratic function of the fermion number $N_F$; and (iii) it is negative in most of the Hilbert space. The latter property leads to a possible quantum avoidance of the singularity (“cosmological bounce”), and suggests imposing the boundary condition that the wave function of the Universe vanish when the volume of space tends to zero (a type of boundary condition which looks like a final-state condition when considering the big crunch inside a black hole). The space of solutions is a mixture of “discrete-spectrum states” (parametrized by a few constant parameters, and known in explicit form) and of continuous-spectrum states (parametrized by arbitrary functions entering some initial-value problem). The predominantly negative values of the squared-mass term lead to a “bottle effect” between small-volume universes and large-volume ones, and to a possible reduction of the continuous spectrum to a discrete spectrum of quantum states looking like excited versions of the Planckian-size universes described by the discrete states at fermionic levels $N_F=0$ and 1.

Recent discoveries of optical signatures of black holes in dwarf galaxies indicates that low-mass galaxies can indeed host intermediate massive black holes. This motivates the assessment of the resulting effect on the host dark matter density profile, and the consequences for the constraints on the plane of the dark matter annihilation cross section versus mass, stemming from the nonobservation of gamma rays from local dwarf spheroidals with the Fermi Large Area Telescope. We compute the density profile using three different prescriptions for the black hole mass associated with a given spheroidal galaxy, and taking into account the cutoff to the density from dark matter pair-annihilation. We find that the limits on the dark matter annihilation rate from observations of individual dwarfs are enhanced by factors of a few up to $10^6$, depending on the specific galaxy, on the black hole mass prescription, and on the dark matter particle mass. We estimate limits from combined observations of a sample of 15 dwarfs, for a variety of assumptions on the dwarf black hole mass and on the dark matter density profile prior to adiabatic contraction. We find that if black holes are indeed present in local dwarf spheroidals, then, independent of assumptions, (i) the dark matter interpretation of the Galactic center gamma-ray excess would be conclusively ruled out, (ii) wino dark matter would be excluded up to masses of about 3 TeV, and (iii) vanilla thermal relic weakly interacting massive particles must be heavier than 100 GeV.

In the framework of a nonuniversal $U(1{)}^{\prime }$ extension of the standard model, we propose a scalar candidate for cold dark matter which exhibits interactions with ordinary matter through Higgs and gauge bosons. Using limits from low energy observables, we find constraints on the new physics parameters of the model associated to the extra Abelian symmetry, especially the mass of the additional neutral gauge boson $Z^{\prime }$ and the new gauge coupling constant. We find that for the lower experimental limit $M_{Z^{\prime }}=3\mathrm{TeV}$ constrained by direct research at LHC, the ratio between the $U(1{)}^{\prime }$ and $SU(2{)}_L$ gauge coupling constants is around 0.4. Taking into account this limit and the observable relic density of the Universe, we search for new constraints on the mass of the dark matter particle of the model. We find that for a Higgsphobic model, the mass of the scalar dark matter must be $M_{\sigma }=70\mathrm{GeV}$. We also find different kinematical threshold and resonances that enhance the dispersion of dark matter into ordinary matter for different regions of the space of parameters of the model, obtaining masses as low as 1.3 GeV and as large as 125 GeV without allowed intermediate regions due to resonances.

We compute nonperturbative gluon spectral functions at finite temperature in quenched QCD with the maximum entropy method. We also provide a closed loop equation for the spectral function of the energy-momentum tensor in terms of the gluon spectral function. This setup is then used for computing the shear viscosity over entropy ratio $\eta /s$ in a temperature range from about $0.4T_c$ to $4.5T_c$. The ratio $\eta /s$ has a minimum at about $1.25T_c$ with the value of about 0.115. We also discuss extensions of the present results to QCD.

Recently, we studied perturbations in the Lemaître-Tolman-Bondi cosmological model by applying the second-order perturbation theory in the dust Friedmann-Lemaître-Robertson-Walker universe model. Before this work, the same subject was studied in some papers by analyzing linear perturbations in the Lemaître-Tolman-Bondi cosmological model under the assumption proposed by Clarkson, Clifton, and February, in which two perturbation variables are negligible. However, it is a nontrivial issue in what situation the Clarkson-Clifton-February assumption is valid. In this paper, we investigate differences between these two approaches. It is shown that, in general, these two approaches are not compatible with each other. That is, in our perturbative procedure, the Clarkson-Clifton-February assumption is not valid at the order of our interest.

Scattering equations for tree-level amplitudes are viewed in the context of string theory. To this end we are led to define a new dual model whose amplitudes coincide with string theory in both the small and large ${\alpha }^{\prime }$ limit, computed algebraically on the surface of solutions to the scattering equations. Because it has support only on the scattering equations, it can be solved exactly, yielding a simple resummed model for ${\alpha }^{\prime }$ corrections to all orders. We use the same idea to generalize scattering equations to amplitudes with fermions and any mixture of scalars, gluons, and fermions. In all cases checked we find exact agreement with known results.

The baryon spectrum in the Sakai-Sugimoto model in the D4 background with smeared D0 charges is studied. We follow the instanton description of baryons by Hata et al. [Prog. Theor. Phys. 117, 1157 (2007)]. The background corresponds to an excited state with nonzero glue condensate $⟨\text{tr}(F_{\mu \nu }{\tilde{F}}^{\mu \nu })⟩$ which is proportional to the D0 charge density. The baryon size shrinks when we turn on small D0 charge density. But for larger D0 charge density where massive modes in the gauge theory may also take effect, the size of baryons will grow. The difference between baryon masses will become smaller when D0 charge density increases. There may also be indications that the baryon will become unstable and cannot exist for sufficiently large D0 density.

We examine the unitarity of a class of generalized Maxwell U(1) gauge theories in ($2+1$) dimensions containing the pseudodifferential operator ${\square }^{1-\alpha }$, for $\alpha \in [0,1)$. We show that only ${\mathrm{QED}}_3$ and its generalization known as pseudo-QED, for which $\alpha =0$ and $\alpha =1/2$, respectively, satisfy unitarity. The latter plays an important role in the description of the electromagnetic interactions of charged particles confined to a plane, such as in graphene or in heterojunctions displaying the quantum Hall effect. Possible implications of our results on the role of unitarity in the framework of the AdS/CFT correspondence are briefly pointed out at the end.

Two of the most attractive realizations of inflation in supergravity are based upon the presence of a constant Fayet-Iliopoulos (FI) term. In D-term hybrid inflation, it is the FI term itself which sets the energy scale of inflation. Alternatively, the breaking of a $U(1)$ symmetry induced by the FI term can dynamically generate the quadratic potential of chaotic inflation. The purpose of this note is to study the possible UV embedding of these schemes in terms of the “field-dependent FI term” related to a string modulus field which is stabilized by a nonperturbative superpotential. We find that in settings where the FI term drives inflation, gauge invariance prevents a decoupling of the modulus from the inflationary dynamics. The resulting inflation models generically contain additional dynamical degrees of freedom compared to D-term hybrid inflation. However, the dynamical realization of chaotic inflation can be obtained in complete analogy to the case of a constant FI term. We present a simple string-inspired toy model of this type.

We study the process of primordial black hole (PBH) formation at the beginning of the radiation era for the cosmological scenario in which the inflaton is a pseudo-Nambu-Goldstone boson (axion) and there is a coupling of the inflaton with some gauge field. In this model inflation is accompanied by the gauge quanta production, and a strong rise of the curvature power spectrum amplitude at small scales (along with non-Gaussianity) is predicted. We show that data on PBH searches can be used for a derivation of essential constraints on the model parameters in such an axion inflation scenario. We compare our numerical results with the similar results published earlier, in the work [A. Linde, S. Mooij, and E. Pajer, Phys. Rev. D 87, 103506 (2013)].

We measure the direct $CP$ violation asymmetry, $A_{CP}$, in $B\to X_s\gamma$ and the isospin difference of the asymmetry, $\mathrm{\Delta }{A}_{CP}$, using $429{\mathrm{fb}}^{-1}$ of data collected at $\mathrm{\Upsilon }(4S)$ resonance with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage rings operating at the SLAC National Accelerator Laboratory. $B$ mesons are reconstructed from ten charged $B$ final states and six neutral $B$ final states. We find $A_{CP}=+(1.7\pm 1.9\pm 1.0)\%$, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between $A_{CP}$ for charged and neutral decay modes, $\mathrm{\Delta }{A}_{CP}=+(5.0\pm 3.9\pm 1.5)\%$. Using the value of $\mathrm{\Delta }{A}_{CP}$, we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of the Wilson coefficients corresponding to the chromomagnetic dipole and the electromagnetic dipole transitions.

Four-dimensional scalar-tensor theory is considered within two conformal frames, the Jordan frame (JF) and the Einstein frame (EF). The actions for the theory are equivalent and equations of motion can be obtained from each action. It is found that the JF equations of motion, expressed in terms of EF variables, translate directly into and agree with the EF equations of motion obtained from the EF action, provided that certain simple consistency conditions are satisfied, which is always the case. The implication is that a solution set obtained in one conformal frame can be reliably translated into a solution set for the other frame, and therefore the two frames are, at least, mathematically equivalent.

We introduce bosonic ($p-1$)-form fields that couple to the spin connection of the Einstein-Cartan theory of gravity, thus becoming a nontrivial source of spacetime torsion. We analyze all the general features of both the matter and the gravitational sectors of the theory. Finally, we briefly consider the implications of the existence of such fields in different physical settings.

We argue that a unitary description of the formation and evaporation of a black hole implies that the Bekenstein–Hawking entropy is the “entropy of a vacuum”: the logarithm of the number of possible independent ways in which quantum field theory on a fixed classical spacetime background can emerge in a full quantum theory of gravity. In many cases, the covariant entropy counts this entropy—the degeneracy of emergent quantum field theories in full quantum gravity—with the entropy of particle excitations in each quantum field theory giving only a tiny perturbation. In the Rindler description of a (black hole) horizon, the relevant vacuum degrees of freedom manifest themselves as an extra hidden quantum number carried by the states representing the second exterior region; this quantum number is invisible in the emergent quantum field theory. In a distant picture, these states arise as exponentially degenerate ground and excited states of the intrinsically quantum gravitational degrees of freedom on the stretched horizon. The formation and evaporation of a black hole involve processes in which the entropy of collapsing matter is transformed into that of a vacuum and then to that of final-state Hawking radiation. In the intermediate stage of this evolution, entanglement between the vacuum and (early) Hawking radiation develops, which is transferred to the entanglement among final-state Hawking quanta through the evaporation process. The horizon is kept smooth throughout the evolution; in particular, no firewall develops. Similar considerations also apply for cosmological horizons, for example for the horizon of a metastable de Sitter space.

We reexamine the screening mechanism in $f(R)$ gravity using N-body simulations. By explicitly examining the relation between the extrascalar field $\delta f_R$ and the gravitational potential $\varphi$ in the perturbed Universe, we find that the relation between these two fields plays an important role in understanding the screening mechanism. We show that the screening mechanism in $f(R)$ gravity depends mainly on the depth of the potential well and find a useful condition for identifying unscreened haloes in simulations. We also discuss the potential application of our results to real galaxy surveys.

We determine the baryon octet and decuplet masses as well as their wave functions in a covariant three-body Faddeev approach. We work in an approximation where irreducible three-body forces are neglected. In the two-body interactions we take into account a well-explored rainbow-ladder kernel as well as flavor dependent meson-exchange terms motivated from the underlying quark-gluon interaction. Without flavor dependent forces we find agreement with the experimental spectrum on the 5–10 percent level. Including the flavor dependent terms on an exploratory level delivers a $\mathrm{\Sigma }-\mathrm{\Lambda }$ splitting with the correct sign although the magnitude is still too small.

The doubly charged Higgs bosons $H_{1,2}^{\pm \pm }$ would undoubtedly be clear messengers of the new physics. We discuss their mass spectrum and show how experimental data and relations between scalar masses put limits on it. In particular, both the masses of the particles $H_1^0$, $A_1^0$ that play a crucial role in flavor changing neutral current effects and the masses of the additional gauge bosons $W_2$, $Z_2$ are notably important. For instance, if $M_{H_1^0,A_1^0}\simeq 15\mathrm{TeV}$ and $M_{W_2}\simeq 3.76\mathrm{TeV}$, then the lowest mass of $H_1^{\pm \pm }$ is 465 GeV. In contrast, because of the freedom in the parameter space of the full scalar potential, there is no lowest limit on the mass of $H_2^{\pm \pm }$. It is shown to which signals at hadron colliders such relatively light doubly charged scalars might correspond. LHC working at $\sqrt{s}=14\mathrm{TeV}$ will enter into the region where the existence of such particles with minimal masses can be thoroughly explored for a much wider parameter space of the minimal and manifest version of the left-right symmetric model (MLRSM). Taking into account our considerations and present ATLAS and CMS exclusion limits on $M_{H^{\pm \pm }}$, there exist already first partial bounds on some of the MLRSM scalar potential parameters.

We present results for the equation of state in ($2+1$)-flavor QCD using the highly improved staggered quark action and lattices with temporal extent $N_{\tau }=6$, 8, 10, and 12. We show that these data can be reliably extrapolated to the continuum limit and obtain a number of thermodynamic quantities and the speed of sound in the temperature range 130–400 MeV. We compare our results with previous calculations and provide an analytic parameterization of the pressure, from which other thermodynamic quantities can be calculated, for use in phenomenology. We show that the energy density in the crossover region, $145\mathrm{MeV}\le T\le 163\mathrm{MeV}$, defined by the chiral transition, is ${\epsilon }_c=(0.18–0.5)\mathrm{GeV}/{\mathrm{fm}}^3$, i.e., $(1.2–3.1){\epsilon }_{\text{nuclear}}$. At high temperatures, we compare our results with resummed and dimensionally reduced perturbation theory calculations. As a byproduct of our analyses, we obtain the values of the scale parameters $r_0$ from the static quark potential and $w_0$ from the gradient flow.

An interesting possibility to ease the tension between various determinations of $|V_{ub}|$ is to allow a small right-handed contribution to the standard model weak current. The present bounds on such a contribution are fairly weak. We propose new ways to search for such a beyond standard model contribution in semileptonic $B\to \rho \ell \overline{\nu }$ decay. Generalized asymmetries in one, two, or three angular variables are introduced as discriminators, which do not require an unbinned analysis of the fully differential distribution, and a detailed study of the corresponding theoretical uncertainties is performed. A discussion on how binned measurements can access all the angular information follows, which may be useful in both $B\to \rho \ell \overline{\nu }$ and $B\to K^{*}{\ell }^{+}{\ell }^{-}$, and possibly essential in the former decay due to backgrounds. The achievable sensitivity from the available BABAR and Belle data sets is explored, as well as from the anticipated $50{\text{ab}}^{-1}$ Belle II data.