We obtain rotating solutions of regular black holes which are constructed of de Sitter spacetime with the axisymmetric stationary perturbation within the timelike charged thin shell and the Kerr-Newman geometry with sufficiently small rotation outside the shell. To treat the slowly rotating thin shell, we employ the method developed by de la Cruz and Israel. The thin shell is assumed to be composed of a dust in the zero-rotation limit and located inside the inner horizon of the black hole solution. We expand the perturbation in powers of the rotation parameter of the Kerr-Newman metric up to the second order. It is found that with the present treatment, the stress tensor of the thin shell in general has anisotropic pressure, i.e., the thin shell cannot be composed of a dust if the rotational effects are taken into account. However, the thin shell can be composed of a perfect fluid with isotropic pressure if the degrees of freedom appearing in the physically acceptable matching of the two distinct spacetimes are suitably used. We numerically investigate the rotational effects on the spherically symmetric charged regular black hole obtained by Uchikata, Yoshida, and Futamase in detail.

We drop the complexification procedure from the Newman-Janis algorithm and introduce more physical arguments and symmetry properties, and we show how one can generate regular and singular rotating black hole and non-black-hole solutions in Boyer-Lindquist coordinates. We focus on generic rotating regular black holes and show that they are regular on the Kerr-like ring, but physical entities are undefined there. We show that rotating regular black holes have much smaller electric charges, and, with increasing charge, they turn into regular non-black-hole solutions well before their Kerr-Newman counterparts become naked singularities. No causality violations occur in the region inside a rotating regular black hole. The separability of the Hamilton-Jacobi equation for neutral particles is also carried out in the generic case, and the innermost boundaries of circular orbits for particles are briefly discussed. Other, but special, properties pertaining to the rotating regular counterpart of the Ayón-Beato–García regular static black hole are also investigated.

$n$-DBI gravity explicitly breaks Lorentz invariance by the introduction of a unit timelike vector field, thereby giving rise to an extra (scalar) degree of freedom. We look for observational consequences of this mode in two setups. First, we compute the parametrized post-Newtonian (PPN) expansion of the metric to first post-Newtonian order. Surprisingly, we find that the PPN parameters are exactly the same as in general relativity (GR), and no preferred-frame effects are produced. In particular this means that $n$-DBI gravity is consistent with all GR solar system experimental tests. We discuss the origin of such degeneracy between $n$-DBI gravity and GR and suggest it may also hold in higher post-Newtonian order. Second, we study gravitational scalar perturbations of a Friedmann-Robertson-Walker space-time with a cosmological constant $\mathrm{\Lambda }\ge 0$. In the case of de Sitter space, we show that the scalar mode grows as the Universe expands and, in contrast with a canonical scalar field coupled to GR, it does not freeze on superhorizon scales.

We examine the accretion process onto the black hole with a string cloud background, where the horizon of the black hole has an enlarged radius $r_H=2M/(1-\alpha )$, due to the string cloud parameter $\alpha$ ($0\le \alpha <1$). The problem of stationary, spherically symmetric accretion of a polytropic fluid is analyzed to obtain an analytic solution for such a perturbation. Generalized expressions for the accretion rate $\dot{M}$, critical radius $r_s$, and other flow parameters are found. The accretion rate $\dot{M}$ is an explicit function of the black hole mass $M$, as well as the gas boundary conditions and the string cloud parameter $\alpha$. We also find the gas compression ratios and temperature profiles below the accretion radius and at the event horizon. It is shown that the mass accretion rate, for both the relativistic and the nonrelativistic fluid by a black hole in the string cloud model, increases with increase in $\alpha$.

Toward a test of parity violation in a gravity theory, possible effects of Chern-Simons (CS) gravity on an interferometer have been recently discussed. Continuing work initiated in an earlier publication [H. Okawara, K. Yamada, and H. Asada, Phys. Rev. Lett. 109, 231101 (2012)], we study possible altitudinal and directional dependence of relativistic Sagnac effect in CS modified gravity. We compare the CS effects on Sagnac interferometers with the general relativistic Lense-Thirring (LT) effects. Numerical calculations show that the eastbound Sagnac interferometer might be preferred for testing CS separately, because LT effects on this interferometer cancel out. The size of the phase shift induced in the CS model might have an oscillatory dependence also on the altitude of the interferometer through the CS mass parameter $m_{\mathrm{CS}}$. Therefore, the international space station site as well as a ground-based experiment is also discussed.

A refined version of a recently introduced method for analyzing the dynamics of an inhomogeneous irrotational dust universe is presented. A fully nonperturbative numerical computation of the time dependence of volume in this framework leads to the following results. If the initial state of the universe is Einstein–de Sitter with small Gaussian perturbations, then there is no acceleration even though the inhomogeneities strongly affect the evolution. A universe with a positive background curvature can exhibit acceleration, but not in conjunction with reasonable values for the Hubble rate. Thus the correct values for both quantities can be achieved only by introducing a positive cosmological constant. Possible loopholes to this conclusion are discussed; in particular, acceleration as an illusion created by peculiarities of light propagation in an inhomogeneous universe is still possible. Independently of the cosmological constant question, the present formalism should provide an important tool for precision cosmology.

Lepton flavor asymmetries generated at the onset of the oscillations of sterile neutrinos with masses above the electroweak scale can be large enough to partly survive washout and to explain the baryon asymmetry of the Universe. This opens up new regions of parameter space, where leptogenesis is viable within the type-I seesaw framework. In particular, we find it possible that the sterile neutrino masses are substantially below ${10}^9\mathrm{GeV}$, while not being degenerate. However, the required reheat temperature that is determined by the beginning of the oscillations lies some orders of magnitude above the sterile neutrino mass scale.

We analyze a model of hybrid natural inflation based on the smallest non-Abelian discrete group $S_3$. Leading invariant terms in the scalar potential have an accidental global symmetry that is spontaneously broken, providing a pseudo-Goldstone boson that is identified as the inflaton. The $S_3$ symmetry restricts both the form of the inflaton potential and the couplings of the inflaton field to the waterfall fields responsible for the end of inflation. We identify viable points in the model parameter space. Although the power in tensor modes is small in most of the parameter space of the model, we identify parameter choices that yield potentially observable values of $r$ without super-Planckian initial values of the inflaton field.

Black holes are said to have no hair because all of their multipole moments can be expressed in terms of just their mass, charge and spin angular momentum. The recent discovery of approximately equation-of-state-independent relations among certain multipole moments in neutron stars suggests that they are also approximately bald. We here explore the yet unknown origin for this universality. First, we investigate which region of the neutron star’s interior and of the equation of state is most responsible for the universality. We find that the universal relation between the moment of inertia and the quadrupole moment is dominated by the star’s outer core, a shell of width 50%–95% of the total radius, which corresponds to the density range ${10}^{14}\text{–}{10}^{15}\mathrm{g}/{\mathrm{cm}}^3$. In this range, realistic neutron star equations of state are not sufficiently similar to each other to explain the universality observed. Second, we study the impact on the universality of approximating stellar isodensity contours as self-similar ellipsoids. An analytical calculation in the nonrelativistic limit reveals that the shape of the ellipsoids per se does not affect the universal relations much, but relaxing the self-similarity assumption can completely destroy it. Third, we investigate the eccentricity profiles of rotating relativistic stars and find that the stellar eccentricity is roughly constant, with variations of roughly 20%–30% in the region that matters to the universal relations. Fourth, we repeat the above analysis for differentially rotating, noncompact, regular stars and find that this time the eccentricity is not constant, with variations that easily exceed 100%, and moreover universality is lost. These findings suggest that universality arises as an emergent approximate symmetry: as one flows in the stellar-structure phase space from noncompact star region to the relativistic star region, the eccentricity variation inside stars decreases, leading to approximate self-similarity in their isodensity contours, which then leads to the universal behavior observed in their exterior multipole moments.

We show that a particular class of postrecombination phase transitions in the vacuum can lead to localized overdense regions on relatively small scales, roughly ${10}^6$ to ${10}^{10}{M}_{\odot }$, potentially interesting for the origin of large black hole seeds and for dwarf galaxy evolution. Our study suggests that this mechanism could operate over a range of conditions which are consistent with current cosmological and laboratory bounds. One byproduct of phase transition bubble-wall decay may be extra radiation energy density. This could provide an avenue for constraint, but it could also help reconcile the discordant values of the present Hubble parameter ($H_0$) and ${\sigma }_8$ obtained by cosmic microwave background (CMB) fits and direct observational estimates. We also suggest ways in which future probes, including CMB considerations (e.g., early dark energy limits), 21-cm observations, and gravitational radiation limits, could provide more stringent constraints on this mechanism and the sub-eV scale beyond-standard-model physics, perhaps in the neutrino sector, on which it could be based. Late phase transitions associated with sterile neutrino mass and mixing may provide a way to reconcile cosmological limits and laboratory data, should a future disagreement arise.

Scenarios in which the Higgs vacuum arises radiatively and is separated from the origin by a potential barrier at zero temperature are known to be attainable in models with extra singlet scalars, which in the limit of zero barrier height give rise to Coleman-Weinberg realizations of electroweak-symmetry breaking. However, this requires large values of Higgs-portal couplings or a large number $N$ of singlets. This is quantified in detail by considering, for varying $N$, the full two-loop effective potential at zero temperature, as well as finite-temperature effects including the dominant two-loop corrections due to the singlets. Despite the large couplings, two-loop effects near the electroweak scale are under control, and actually better behaved in models with larger couplings yet fewer singlets. Strong first-order phase transitions are guaranteed even in the Coleman-Weinberg scenarios. Cubic Higgs couplings and Higgs associated-production cross sections exhibit deviations from the standard model predictions which could be probed at a linear collider.

Hadronic matrix elements that depend on momentum are required for numerous phenomenological applications. Probing the low-momentum regime is often problematic for lattice QCD computations on account of the restriction to periodic momentum modes. Recently a novel method has been proposed to compute matrix elements at zero momentum, for which straightforward evaluation of the matrix elements would otherwise yield a vanishing result. We clarify an assumption underlying this method, and thereby establish the theoretical framework required to address the associated finite volume effects. Using the pion electromagnetic form factor as an example, we show how the charge radius and two higher moments can be calculated at zero-momentum transfer and determine the corresponding finite volume effects. These computations are performed using chiral perturbation theory to account for modified infrared physics and can be generalized to ascertain finite volume effects for other hadronic matrix elements extracted at zero momentum.

We present a lattice QCD calculation of the polarizability of the neutron and other neutral hadrons that includes the effects of the background field on the sea quarks. This is done by perturbatively reweighting the charges of the sea quarks to couple them to the background field. The main challenge in such a calculation is stochastic estimation of the weight factors, and we discuss the difficulties in this estimation. Here we use an extremely aggressive dilution scheme to reduce the stochastic noise to a manageable level. The pion mass in our calculation is 300 MeV and the lattice size is 3 fm. For the neutron, we find that ${\alpha }_E=2.70(55)\times 10^{-4}{\mathrm{fm}}^3$, which is the most precise lattice QCD determination of the polarizability to date that includes sea effects.

The Higgs discovery has given us the Higgs–gauge sector as a new handle to search for physics beyond the standard model. This includes physics scenarios originally linked to massive gauge boson scattering at high energies. We investigate how one can separately probe the Higgs couplings to the longitudinal and transverse parts of the massive gauge bosons away from this high-energy limit. Deviations from the standard model could originate from higher-dimensional operators, compositeness, or even more fundamentally from a violation of gauge invariance. The signature we propose is the tagging jet kinematics in weak boson scattering for scattering energies close to the Higgs resonance. During the upcoming LHC run at 13 TeV we will be able to test these couplings at the 20% level.

The asymmetry in the forward region production cross section of $D^{\pm }$ is calculated using the heavy quark recombination mechanism for $pp$ collisions at 7 TeV. By suitable choices of four nonperturbative parameters, our calculated results can reproduce those obtained at LHCb. We find $A_p\sim -1\%$ when integrated over $2.0\mathrm{GeV}<p_T<18\mathrm{GeV}$ and $2.2<\eta <4.75$, which agrees with $A_p=-0.96\pm 0.26\pm 0.18\%$ as measured by LHCb. Furthermore, the calculated distributions in $\eta$ and $p_T$ agree reasonably well with those obtained at LHCb.

A measurement of the $B_s^0\to J/\psi \varphi$ decay parameters, updated to include flavor tagging is reported using $4.9{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the ATLAS detector from $\sqrt{s}=7\mathrm{TeV}$ $pp$ collisions recorded in 2011 at the LHC. The values measured for the physical parameters are $$\begin{gathered} {\varphi }_s=0.12\pm 0.25(\text{stat})\pm 0.05(\text{syst})\text{rad} \\ \mathrm{\Delta }{\mathrm{\Gamma }}_s=0.053\pm 0.021(\text{stat})\pm 0.010(\text{syst}){\mathrm{ps}}^{-1} \\ {\mathrm{\Gamma }}_s=0.677\pm 0.007(\text{stat})\pm 0.004(\text{syst}){\mathrm{ps}}^{-1} \\ |A_{\parallel }(0){|}^2=0.220\pm 0.008(\text{stat})\pm 0.009(\text{syst}) \\ |A_0(0){|}^2=0.529\pm 0.006(\text{stat})\pm 0.012(\text{syst}) \\ {\delta }_{\perp }=3.89\pm 0.47(\text{stat})\pm 0.11(\text{syst})\text{rad} \end{gathered}$$where the parameter $\mathrm{\Delta }{\mathrm{\Gamma }}_s$ is constrained to be positive. The $S$-wave contribution was measured and found to be compatible with zero. Results for ${\varphi }_s$ and $\mathrm{\Delta }{\mathrm{\Gamma }}_s$ are also presented as 68% and 95% likelihood contours, which show agreement with the Standard Model expectations.

We present a search for low-mass ($\le 20\mathrm{GeV}/c^2$) weakly interacting massive particles (WIMPs), strong candidates of dark matter particles, using the low-background CsI(Tl) detector array of the Korea Invisible Mass Search experiment. With a total data exposure of 24,524.3 kg days, we search for WIMP interaction signals produced by nuclei recoiling from WIMP-nuclear elastic scattering with visible energies between 2 and 4 keVee (electron-equivalent energy). The observed energy distribution of candidate events is consistent with null signals, and upper limits of the WIMP-proton spin-independent interaction are set with a 90% confidence level. The observed limit covers most of the low-mass region of parameter space favored by the DAMA annual modulation signal assuming the standard halo model.

The BICEP-2 team has recently reported the positive detection of cosmic microwave background $B$-mode polarization. Although uncertainties due to galactic dust foregrounds remain, it is a constructive exercise to work out the implications of presuming some part of the detected $B$-mode signal to be due to primordial gravitational waves. Were a positive detection of a tensor-to-scalar ratio larger than $r\gtrsim \mathcal{O}({10}^{-2})$ confirmed, detecting a tilt in the tensor spectrum comparable to that observed for the scalar power spectrum becomes in principle possible. We wish to explore in this brief paper the possibility of there being a blue tilt to the primordial gravitational-wave spectrum. Such a tilt would be incompatible with standard inflationary models, although it was predicted some years ago in the context of a mechanism that thermally generates the primordial perturbations through a Hagedorn phase of string cosmology. By scrutinizing the data with priors informed by a model that is immediately falsifiable, but which predicts features that may be favored by the data—namely a blue tensor tilt with an induced and complementary red tilt to the scalar spectrum, with a naturally large tensor-to-scalar ratio that relates to both—we offer a useful straw model against which to test the predictions of single-field inflation.

It is shown that the inhomogeneous chiral condensate in the Gross-Neveu (GN) model takes the chiral spiral form, even though the thermodynamic functional depends only on the chiral scalar density. It is the inhomogeneity of the chiral scalar condensate that drives the spatial modulations of the pseudoscalar one. The result has broader implications once we start to think of fundamental theories behind the effective models. In particular, some effective interactions—which may be omitted for descriptions of the homogeneous phases—can be dynamically enhanced due to the spatial modulations of the large mean fields. Implications for the four-dimensional counterparts of the GN model are discussed. In a quark matter context, proper forms of the effective models for the inhomogeneous phases are speculated, through considerations on the Fermi-Dirac sea coupling.

We study the frequency dependence of all the chiral vortical and magnetic conductivities for a relativistic gas of free chiral fermions and for a strongly coupled conformal field theory with holographic dual in four dimensions. Both systems have gauge and gravitational anomalies, and we compute their contribution to the conductivities. The chiral vortical conductivities and the chiral magnetic conductivity in the energy current show a frequency dependence in the form of a delta centered at zero frequency. This highly discontinuous behavior is a natural consequence of the Ward identities that include the energy momentum tensor. We discuss the physical interpretation of this result and its possible implications for the quark gluon plasma as created in heavy ion collisions. In the Appendix we discuss why the chiral magnetic effect seems to vanish in the consistent current for a particular implementation of the axial chemical potential.