A new class of vacuum black holes for the most general gravity theory leading to second order field equations in the metric in even dimensions is presented. These space-times are locally anti-de Sitter in the asymptotic region, and are characterized by a continuous parameter that does not enter in the conserve charges, nor it can be reabsorbed by a coordinate transformation: it is therefore a purely gravitational hair. The black holes are constructed as a warped product of a two-dimensional space-time, which resembles the $r–t$ plane of the Bañados-Teitelboim-Zanelli black hole, times a warp factor multiplying the metric of a $D-2$-dimensional Euclidean base manifold, which is restricted by a scalar equation. It is shown that all the Noether charges vanish. Furthermore, this is consistent with the Euclidean action approach: even though the black hole has a finite temperature, both the entropy and the mass vanish. Interesting examples of base manifolds are given in eight dimensions which are products of Thurston geometries, giving then a nontrivial topology to the black hole horizon. The possibility of introducing a torsional hair for these solutions is also discussed.

Many models of inflation predict oscillatory features in the bispectrum of primordial fluctuations. Since it has been shown that primordial non-Gaussianity can lead to a scale-dependent halo bias, we investigate the effect of oscillations in the three-point function on the clustering of dark-matter halos. Interestingly, we find that features in the inflaton potential such as oscillations or sharp steps get imprinted in the mass dependence of the non-Gaussian halo bias. In this paper, we focus on models displaying a sharp feature in the inflaton potential as well as resonant non-Gaussianity. In both cases, we find a strong scale dependence for the non-Gaussian halo bias with a slope similar to that of the local model. In the resonant case, we find that the non-Gaussian bias oscillates with halo mass, a novel feature that is unique to this type of models. In the case of a sharp feature in the inflaton potential, we find that the clustering of halos is enhanced at the mass scale corresponding to the Fourier mode that exited the horizon when the inflaton was crossing the feature in the potential. Both of these are new effects that open the possibility of characterizing the inflationary potential with large-scale-structure surveys. We briefly discuss the prospects for detecting these non-Gaussian effects.

For very general scalar-field theories in which the equations of motion are at second order, we evaluate the three-point correlation function of primordial scalar perturbations generated during inflation. We show that the shape of non-Gaussianities is well approximated by the equilateral type. The equilateral nonlinear parameter $f_{\mathrm{NL}}^{\mathrm{equil}}$ is derived on the quasi-de Sitter background, where the slow-variation parameters are much smaller than unity. We apply our formula for $f_{\mathrm{NL}}^{\mathrm{equil}}$ to a number of single-field models of inflation—such as k-inflation, k-inflation with Galileon terms, potential-driven Galileon inflation, nonminimal coupling models (including field-derivative coupling models), and Gauss-Bonnet gravity.

Observation of some low-energy processes in the flavor physics regime may require the existence of supersymmetry with two relatively large $R$-parity-violating couplings of the ${\lambda }^{\prime }$-type, together with reasonably light superparticles. At the LHC, such interactions would be expected to give rise to clear signals with convenient leptonic triggers, including some multileptons of the same sign. We undertake a detailed investigation of these signals taking care to correlate with low-energy requirements and taking proper account of the standard model backgrounds as well as the $R$-parity-conserving sector of the supersymmetric model. We find clear indications that $R$-parity violation as envisaged in this scenario can be detected at the LHC—even, perhaps, in the early runs.

In the scenario of cold electroweak baryogenesis, oscillations of the Higgs field lead to metastable domains of unbroken phase where the Higgs field nearly vanishes. Those domains have also been identified with the $W-t-\overline{t}$ bags, a nontopological solitons made of large number ($\sim 1000$) of gauge quanta and heavy (top and antitop) quarks. As real-time numerical studies had shown, sphalerons (topological transition events violating the baryon number) occur only inside those bags. In this work we estimate the amount of $CP$ violation in this scenario coming from the standard model, via the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix, resulting in top-minus-antitop difference of the population in the bags. Since these tops/antitops are recycled by sphalerons, this population difference leads directly to the baryonic asymmetry of the Universe. We look at the effect appearing in the 4th order in weak $W$ diagrams describing interference of different quark flavor contributions. We found that there are multiple cancellations of diagrams and clearly sign-definite effect appears only in the 6th-order expansion over flavor-dependent phases. We then estimate contributions to these diagrams in which weak interaction occurs (i) inside, (ii) near and (iii) far from the $W-t-\overline{t}$ b-bags, optimizing the contributions in each of them. We conclude that the second (near) scenario is the dominant one, producing $CP$ violation of the order of ${10}^{-10}$, in our crude estimates. Together with the baryon violation rate of about ${10}^{-2}$, previously demonstrated for this scenario, it puts the resulting asymmetry close to what is needed to explain the observed baryonic asymmetry in the Universe. Our answer also has a definite sign, which apparently seems to be the correct one.

Dirac’s idea of taking the square root of constraints is applied to the case of extended objects concentrating on membranes in $D=4$ space-time dimensions. The resulting equation is Lorentz invariant and predicts an infinite hierarchy of positive and negative masses (tension). There are no tachyonic solutions.

We argue that the electron star and the anti–de Sitter (AdS) Dirac hair solution are two limits of the free charged Fermi gas in AdS. Spectral functions of holographic duals to probe fermions in the background of electron stars have a free parameter that quantifies the number of constituent fermions that make up the charge and energy density characterizing the electron star solution. The strict electron star limit takes this number to be infinite. The Dirac hair solution is the limit where this number is unity. This is evident in the behavior of the distribution of holographically dual Fermi surfaces. As we decrease the number of constituents in a fixed electron star background the number of Fermi surfaces also decreases. An improved holographic Fermi ground state should be a configuration that shares the qualitative properties of both limits.

An action principle for the generalized harmonic formulation of general relativity is presented. The action is a functional of the spacetime metric and the gauge source vector. An action principle for the Z4 formulation of general relativity has been proposed recently by Bona, Bona-Casas, and Palenzuela. The relationship between the generalized harmonic action and the Bona, Bona-Casas, and Palenzuela action is discussed in detail.

We study the conditions of a possible static equilibrium between spherically symmetric, electrically charged or neutral black holes and ambient matter. The following kinds of matter are considered: (1) neutral and charged matter with a linear equation of state $p_r=w\rho$ (for neutral matter the results of our previous work are reproduced), (2) neutral and charged matter with $p_r\sim {\rho }^m$, $m>1$, and (3) the possible presence of a “vacuum fluid” (the cosmological constant or, more generally, anything that satisfies the equality $T_0^0=T_1^1$ at least at the horizon). We find a number of new cases of such an equilibrium, including those generalizing the well-known Majumdar-Papapetrou conditions for charged dust. It turns out, in particular, that ultraextremal black holes cannot be in equilibrium with any matter in the absence of a vacuum fluid; meanwhile, matter with $w>0$, if it is properly charged, can surround an extremal charged black hole.

We discuss a new ringdown frequency mode for vacuum perturbations of the Kerr black hole. We evolve initial data for the vacuum radial Teukolsky equation using a near horizon approximation and find a frequency mode analogous to that found in a recent study of radiation generated by a plunging particle close to the Kerr horizon. We discuss our results in the context of that study. We also explore the utility of this mode by fitting a numerical waveform with a combination of the usual quasinormal modes and the new oscillation frequency.

We present the first experimental test of Lorentz invariance using the frequency difference between counter-propagating modes in an asymmetric odd-parity optical resonator. This type of test is $\sim {10}^4$ more sensitive to odd-parity and isotropic (scalar) violations of Lorentz invariance than equivalent conventional even-parity experiments due to the asymmetry of the optical resonator. The disadvantages of odd-parity resonators have been negated by the use of counter-propagating modes, delivering a high level of immunity to environmental fluctuations. With a nonrotating experiment our result limits the isotropic Lorentz violating parameter ${\tilde{\kappa }}_{\mathrm{tr}}$ to $3.4\pm 6.2\times {10}^{-9}$, the best reported constraint from direct measurements. Using this technique the bounds on odd-parity and scalar violations of Lorentz invariance can be improved by many orders of magnitude.

Color superconductivity in high-density QCD exhibits the color-flavor-locked phase. To explore zero modes in the color-flavor-locked phase in the presence of a non-Abelian vortex with an SU(2) symmetry in the vortex core, we apply the index theorem to the Bogoliubov-de Gennes (BdG) Hamiltonian. From the calculation of the topological index, we find that triplet, doublet and singlet sectors of SU(2) have certain number of chiral Majorana zero modes in the limit of vanishing chemical potential. We also solve the BdG equation by the use of the series expansion to show that the number of zero modes and their chirality match the result of the index theorem. From particle-hole symmetry of the BdG Hamiltonian, we conclude that if and only if the index of a given sector is odd, one zero mode survives generically for a finite chemical potential. We argue that this result should hold nonperturbatively even in the high-density limit.

The production of one hard jet in association with missing transverse energy is a major LHC search channel motivated by many scenarios for physics beyond the standard model. In scenarios with a weakly interacting dark matter candidate, like supersymmetry, it arises from the associated production of a quark partner with the dark matter agent. We present the next-to-leading-order cross section calculation as the first application of the fully automized MadGolem package. We find moderate corrections to the production rate with a strongly reduced theory uncertainty.

The chiral condensate and dressed Polyakov loop at finite temperature and density have been investigated in the framework of the $N_f=2+1$ Nambu-Jona-Lasinio (NJL) model with two degenerate $u$, $d$ quarks and one strange quark. In the case of explicit chiral symmetry breaking with physical quark masses, it is found that the phase transitions for light $u$, $d$, and $s$ quark are sequentially happened, and the separation between the transition lines for different flavors becomes wider and wider with the increase of baryon density. For each flavor, the pseudocritical temperatures for chiral condensate and dressed Polyakov loop differ in a narrow transition range in the lower baryon density region, and the two transitions coincide in the higher baryon density region.

We report the first observation of the radiative decay $B^0\to \varphi K^0\gamma$ using a data sample of $772\times {10}^6$ $B\overline{B}$ pairs collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We observe a signal of $37\pm 8$ events with a significance of 5.4 standard deviations including systematic uncertainties. The measured branching fraction is $\mathcal{B}(B^0\to \varphi K^0\gamma )=(2.74\pm 0.60\pm 0.32)\times {10}^{-6}$, where the uncertainties are statistical and systematic, respectively. We also report the first measurements of time-dependent $CP$-violation parameters: ${\mathcal{S}}_{\varphi K_S^0\gamma }=+{0.74}_{-1.05}^{+0.72}(\mathrm{stat}{)}_{-0.24}^{+0.10}(\mathrm{syst})$ and ${\mathcal{A}}_{\varphi K_S^0\gamma }=+0.35\pm 0.58(\mathrm{stat}{)}_{-0.10}^{+0.23}(\mathrm{syst})$. Furthermore, we measure $\mathcal{B}(B^{+}\to \varphi K^{+}\gamma )=(2.48\pm 0.30\pm 0.24)\times {10}^{-6}$, ${\mathcal{A}}_{CP}=-0.03\pm 0.11\pm 0.08$, and find that the signal is concentrated in the $M_{\varphi K}$ mass region near threshold.

A variety of neutrino flavor conversion phenomena occur in core-collapse supernova, due to the large neutrino density close to the neutrinosphere, and the importance of the neutrino-neutrino interaction. Three different regimes have been identified so far, usually called the synchronization, the bipolar oscillations, and the spectral split. Using the formalism of polarization vectors, within two flavors, we focus on the spectral split phenomenon and we show for the first time that the physical mechanism underlying the neutrino spectral split is a magnetic resonance phenomenon. In particular, we show that the precession frequencies fulfill the magnetic resonance conditions. Our numerical calculations show that the neutrino energies and the location at which the resonance takes place in the supernova coincide well with the neutrino energies at which a spectral swap occurs. The corresponding adiabaticity parameters present spikes at the resonance location.

We revisit the Bogomol’nyi-Prasad-Sommerfeld (BPS) monopoles spectrum of the supersymmetric $CP(N-1)$ two-dimensional model with ${\mathcal{Z}}_N$-symmetric twisted masses $m_l$ ($l=0,1,\dots ,N-1$). A related issue we address is that of the curves of marginal stability (CMS) in this theory. Previous analyses were incomplete. We close the gap by exploiting a number of consistency conditions. In particular, we amend the Dorey formula for the BPS spectrum. Our analysis is based on the exact Veneziano—Yankielowicz-type superpotential and on the strong-coupling spectrum of the theory found from the mirror representation at small masses, $|m_l|\ll \Lambda$. We show that at weak coupling the spectrum, with necessity, must include $N-1$ BPS towers of states, instead of just one, as was thought before. Only one of the towers is seen in the quasiclassical limit. We find the corresponding CMS for these towers, and argue that in the large-$N$ limit they become circles, filling out a band on the plane of a single mass parameter of the model at hand. Inside the CMS, $N-1$ towers collapse into $N$ stable states.

We study the particle motion in the space-time of a Kehagias-Sfetsos black hole which is a static spherically symmetric solution of a Hořava-Lifshitz gravity model. This model reduces to general relativity in the infrared limit and deviates slightly from detailed balance. Taking the viewpoint that the model is essentially a ($3+1$)-dimensional modification of general relativity we use the geodesic equation to determine the motion of massive and massless particles. We solve the geodesic equation exactly by using numerical techniques. We find that neither massless nor massive particles with nonvanishing angular momentum can reach the singularity at $r=0$. Next to bound and escape orbits that are also present in the Schwarzschild space-time we find that new types of orbits exist: manyworld bound orbits as well as two-world escape orbits. We also discuss observables such as the perihelion shift and the light deflection.

We propose a deepening of the relativity principle according to which the invariant arena for nonquantum physics is a phase space rather than spacetime. Descriptions of particles propagating and interacting in spacetimes are constructed by observers, but different observers, separated from each other by translations, construct different spacetime projections from the invariant phase space. Nonetheless, all observers agree that interactions are local in the spacetime coordinates constructed by observers local to them. This framework, in which absolute locality is replaced by relative locality, results from deforming energy-momentum space, just as the passage from absolute to relative simultaneity results from deforming the linear addition of velocities. Different aspects of energy-momentum space geometry, such as its curvature, torsion and nonmetricity, are reflected in different kinds of deformations of the energy-momentum conservation laws. These are in principle all measurable by appropriate experiments. We also discuss a natural set of physical hypotheses which singles out the cases of energy-momentum space with a metric compatible connection and constant curvature.