In this paper, we aim to address several important issues about the recently developed lattice Boltzmann (LB) model for relativistic hydrodynamics [M. Mendoza, B. Boghosian, H. Herrmann, and S. Succi, Phys. Rev. Lett. 105, 014502 (2010); Phys. Rev. D 82, 105008 (2010)]. First, we study the conservation law of the particle number in the relativistic LB model. Through the Chapman-Enskog analysis, it is shown that in the relativistic LB model the conservation equation of the particle number is a convection-diffusion equation rather than a continuity equation, which makes the evolution of the particle number dependent on the relaxation time. Furthermore, we investigate the origin of the discontinuities that appeared in the relativistic problems with high viscosities, which were reported in a recent study [D. Hupp, M. Mendoza, I. Bouras, S. Succi, and H. Herrmann, Phys. Rev. D 84, 125015 (2011)]. A multiple-relaxation-time relativistic LB model is presented to examine the influences of different relaxation times on the discontinuities. Numerical experiments show the discontinuities can be eliminated by setting the relaxation time ${\tau }_e$ (related to the bulk viscosity) to be sufficiently smaller than the relaxation time ${\tau }_{\nu }$ (related to the shear viscosity). Meanwhile, it is found that the relaxation time ${\tau }_{\epsilon }$, which has no effect on the conservation equations at the Navier-Stokes level, will affect the numerical accuracy of the relativistic LB model. Moreover, the accuracy of the relativistic LB model for simulating moderately relativistic problems is also investigated.

We classify the half-supersymmetric “domain walls,” i.e., branes of codimension one, in toroidally compactified IIA/IIB string theory and show to which gauged supergravity theory each of these domain walls belong. We use as input the requirement of supersymmetric Wess-Zumino terms, the properties of the $E_{11}$ Kac-Moody algebra and the embedding tensor formalism. We show that the number of half-supersymmetric domain walls is a multiple of the number of corresponding central charges in the supersymmetry algebra, where the multiplicity is related to the degeneracy of the Bogomolnyi-Prasad-Sommerfield conditions.

This is the first of two papers on computing the self-force in a radiation gauge for a particle of mass $\mathfrak{m}$ moving in circular, equatorial orbit about a Kerr black hole. In the extreme-mass-ratio inspiral (EMRI) framework, with mode-sum renormalization, we compute the renormalized value of the quantity $H≔\frac{1}{2}{h}_{\alpha \beta }{u}^{\alpha }{u}^{\beta }$, gauge-invariant under gauge transformations generated by a helically symmetric gauge vector; here, $h_{\alpha \beta }$ is the metric perturbation, $u^{\alpha }$ the particle’s 4-velocity. We find the related order $\mathfrak{m}$ correction to the particle’s angular velocity at fixed renormalized redshift (and to its redshift at fixed angular velocity), each of which can be written in terms of $H$. The radiative part of the metric perturbation is constructed from a Hertz potential that is extracted from the Weyl scalar by an algebraic inversion T. S. Keidl et al., Phys. Rev. D 82, 124012 (2010). We then write the spin-weighted spheroidal harmonics as a sum over spin-weighted spherical harmonics ${}_{s}Y_{\ell m}$ and use mode-sum renormalization to find the renormalization coefficients by matching a series in $L=\ell +1/2$ to the large-$L$ behavior of the expression for $H$. The nonradiative parts of the perturbed metric associated with changes in mass and angular momentum are calculated in the Kerr gauge.

We construct a rank-3 finite temperature logarithmic conformal field theory starting from a higher-derivative scalar field model in the Banñados-Teitelboim-Zanelli black hole background. Its zero temperature limit reduces to a rank-3 logarithmic conformal field theory in the ${\mathrm{AdS}}_3$ background. For a tricritical generalized massive gravity, we read off the log-square quasinormal frequencies of graviton from the poles of the retarded Green’s function in the momentum space. After using the truncation process, we find quasinormal frequencies from a unitary conformal field theory. Finally, employing the retarded Green’s functions on the boundary, we compute the absorption cross sections of Banñados-Teitelboim-Zanelli black hole which show feature of higher-order differential equations for scalars.

It has recently been shown that it is not possible to impose the Lorentz gauge condition in a cosmological space-time using the Gupta-Bleuler method of quantization. It was also shown that it is possible to add ${\nabla }_{\mu }{A}^{\mu }$ as a new degree of freedom to the electromagnetic field and that this new degree of freedom might be the dark energy which is producing the accelerated expansion of the Universe. In this paper, I show that the Lorentz gauge condition can be imposed using Dirac’s method of quantizing constrained dynamical systems. I also compute the vacuum expectation value of the energy-momentum tensor and show that it vanishes. Thus, in Dirac’s approach, the electromagnetic field does not make a contribution to the dark energy.

In this paper we constructed a semirealistic cosmological model in a dynamic domain wall framework. Our universe is considered to be a ($3+1$) dimensional dynamic domain wall in a higher dimensional Einstein-Maxwell-Born-Infeld background. One of our interesting outcomes from the effective Hubble equation for the domain wall dynamics is that it contains an additional component of “dark matter” which is induced from the charge of the bulk Born-Infeld gauge field. In this background spacetime we have studied the cosmological dynamics of the domain wall. In addition to the Born-Infeld gauge field if we consider additional pure gauge field, a nonsingular bounce happens at the early stage with a smooth transition between the contracting and the expanding phase.

We present the first orbit-integrated self force effects on the gravitational waveform for an intermediate (extreme) mass ratio inspiral source. We consider the quasi-circular motion of a particle in the spacetime of a Schwarzschild black hole and study the dependence of the dephasing of the corresponding gravitational waveforms due to ignoring the conservative piece of the self force. We calculate the cumulative dephasing of the waveforms and their overlap integral, and discuss the importance of the conservative piece of the self force in detection and parameter estimation. For long templates the inclusion of the conservative piece is crucial for gravitational-wave astronomy, yet may be ignored for short templates with little effect on detection rate. We then discuss the effect of the mass ratio and the start point of the motion on the dephasing.

Initial data for numerical evolutions of binary-black holes have been dominated by “conformally flat” (CF) data (i.e., initial data where the conformal background metric is chosen to be flat) because they are easy to construct. However, CF initial data cannot simulate nearly extremal spins, while more complicated “conformally curved” initial data (i.e., initial data in which the background metric is not explicitly chosen to be flat), such as initial data where the spatial metric is chosen to be proportional to a weighted superposition of two Kerr-Schild black holes can. Here we establish the consistency between the astrophysical results of these two initial data schemes for nonspinning binary systems. We evolve the inspiral, merger, and ringdown of two equal-mass, nonspinning black holes using superposed Kerr-Schild initial data and compare with an analogous simulation using CF initial data. We find that the resultant gravitational-waveform phases agree to within $\delta \varphi \lesssim {10}^{-2}$ radians and the amplitudes agree to within $\delta A/A\lesssim 5\times {10}^{-3}$, which are within the numerical errors of the simulations. Furthermore, we find that the final mass and spin of the remnant black hole agree to one part in ${10}^5$.

We examine a deformed quantum mechanics in which the commutator between coordinates and momenta is a function of momenta. The Jacobi identity constraint on a two-parameter class of such modified commutation relations (MCR’s) shows that they encode an intrinsic maximum momentum; a subclass of which also implies a minimum position uncertainty. Maximum momentum causes the bound state spectrum of the one-dimensional harmonic oscillator to terminate at finite energy, whereby classical characteristics are observed for the studied cases. We then use a semiclassical analysis to discuss general concave potentials in one dimension and isotropic power-law potentials in higher dimensions. Among other conclusions, we find that in a subset of the studied MCR’s, the leading order energy shifts of bound states are of opposite sign compared to those obtained using string-theory motivated MCR’s, and thus these two cases are more easily distinguishable in potential experiments.

The CoGeNT and CRESST WIMP direct detection experiments have recently observed excesses of nuclear recoil events, while the DAMA/LIBRA experiment has a long-standing annual modulation signal. It has been suggested that these excesses may be due to light masses of $m_{\chi }\sim 5–10\mathrm{GeV}$, weakly interacting massive particles (WIMPs). The Earth’s motion with respect to the Galactic rest frame leads to a directional dependence in the WIMP scattering rate, providing a powerful signal of the Galactic origin of any recoil excess. We investigate whether direct detection experiments with directional sensitivity have the potential to observe this anisotropic scattering rate with the elastically scattering light WIMPs proposed to explain the observed excesses. We find that the number of recoils required to detect an anisotropic signal from light WIMPs at $5\sigma$ significance varies from 7 to more than 190 over the set of target nuclei and energy thresholds expected for directional detectors. Smaller numbers arise from configurations where the detector is only sensitive to recoils from the highest-speed, and hence most anisotropic, WIMPs. However, the event rate above the threshold is very small in these cases, leading to the need for large experimental exposures to accumulate even a small number of events. To account for this sensitivity to the tail of the WIMP velocity distribution, whose shape is not well known, we consider two exemplar halo models spanning the range of possibilities. We also note that for an accurate calculation, the Earth’s orbital speed must be averaged over. We find that the exposures required to detect 10 GeV WIMPs at a WIMP-proton cross section of ${10}^{-4}\mathrm{pb}$ are of order ${10}^3\mathrm{kg}\mathrm{day}$ for a 20 keV energy threshold, within reach of planned directional detectors. Lower WIMP masses require higher exposures and/or lower energy thresholds for detection.

Scalar decay into gravitinos is studied in the presence of $D$-term supersymmetry (SUSY) breaking. The gravitinos produced by the decay of coherent oscillations of scalar fields, such as moduli and inflatons, cause cosmological problems. We show the general formula for the partial decay rate of the scalar into two gravitinos. Applying it to a concrete model of $D$-term SUSY breaking, we find that $D$-term SUSY breaking can suppress gravitino production.

The high-mass end of the halo mass function is a sensitive probe of primordial non-Gaussianity (NG). In a recent study [9], we have computed the NG halo mass function in the context of the excursion set theory and shown that the primordial NG imprint is coupled to that induced by the nonlinear collapse of dark matter halos. We also found an excellent agreement with N-body simulation results. Here, we perform a more accurate computation which accounts for the interval validity of the bispectrum expansion to next-to-leading order and extend the calculation to the case of a nonvanishing primordial trispectrum.

The Higgs-top model is studied by a nonperturbative variational extension of the Gaussian effective potential that incorporates fermions. In the limit of a very strong Yukawa coupling the one-loop result is shown to follow a single-parameter scaling while the Gaussian fluctuations give rise to important deviations from scaling and to a reduction of the vacuum expectation value and of the top mass. A good general agreement is found with lattice data when a comparison can be made. The vacuum is shown to be stable for any choice of the Yukawa coupling, at variance with renormalized perturbation theory. Analytical results are provided for a few observables like the renormalized mass of the Higgs boson and its wave function renormalization constant. Extensions to gauge theories like QCD are briefly discussed.

We discuss the role that Higgs coupling measurements can play in differentiating supersymmetric extensions of the Standard Model. Fitting current LHC data to the Higgs couplings, we find that the likelihood fit shows a preference in the direction of suppressed (enhanced) bottom (top) quark couplings. In the minimal supersymmetric Standard Model, we demonstrate that for $\tan \beta >1$, there is tension in achieving such fermion couplings due to the structure of the Higgs quartic couplings. In anticipation of interpreting supersymmetric models with future data, we determine a single straightforward condition required to access the region of coupling space preferred by current data.

The contribution of the $R$-parity violating minimal supersymmetric standard model to the neutron beta decay at the one-loop level is investigated. It is found that the baryon number and $R$-parity violating interactions contribute to the $D$ correlation through one-loop corrections, while the tree-level prediction is vanishing. The Fierz interference term is also investigated at the one-loop level by considering the lepton number and $R$-parity violating interactions. We show that future experimental progress can provide us with better constraints on some of the combinations of $R$-parity violating couplings.

Different methods for extracting resonance parameters from Euclidean lattice field theory are tested. Monte Carlo simulations of the $O(4)$ nonlinear sigma model are used to generate energy spectra in a range of different volumes both below and above the inelastic threshold. The applicability of the analysis methods in the elastic region is compared. Problems which arise in the inelastic region are also emphasized.

We analyze the relation between Faddeev-Popov eigenmodes and gluon-momentum components in the Coulomb gauge using SU(3) lattice QCD. In the Coulomb gauge, the color-Coulomb energy is largely enhanced by near-zero Faddeev-Popov eigenmodes, which would lead to the confining potential. By the ultraviolet-momentum gluon cut, the color-Coulomb energy and the Faddeev-Popov spectrum are almost unchanged. In contrast to the ultraviolet insensitivity, the color-Coulomb energy and the Faddeev-Popov eigenmodes drastically change by infrared-momentum gluon cut. Without infrared gluons, the color-Coulomb energy tends to become nonconfining, and near-zero Faddeev-Popov eigenmodes vanish. We also investigate the full Faddeev-Popov eigenmodes, and find that infrared gluons widely influence both high and low Faddeev-Popov eigenmodes.

The charmonium transitions from the ${\chi }_{cJ}$ states to ${\eta }_c$ with emission of one or two pions are considered. It is shown that the only processes of such type arising in the leading order in the QCD multipole expansion are the decays ${\chi }_{c1}\to {\eta }_c{\pi }^{+}{\pi }^{-}$ and ${\chi }_{c0}\to {\eta }_c{\pi }^0$. The absolute rate of the latter decay, in spite of being isotopically suppressed, is by about an order of magnitude larger than that of the former, so that the branching fractions for the two processes are approximately equal, and are expected to be significantly below the recent upper bound reported by BESIII. The rates of both decays are also related to that of another similar transition $h_c\to J/\psi {\pi }^0$.

The much debated issue of the transverse single spin asymmetry $A_N$ observed in the inclusive large $P_T$ production of a single hadron in $pp$ interactions, $p^{\uparrow }p\to \pi X$, is considered in a transverse momentum dependent factorization scheme. A previous result [M. Anselmino et al., Phys. Rev. D 71, 014002 (2005), M. Anselmino et al., Phys. Rev. D 73, 014020 (2006)] stating that the maximum contribution of the Collins effect is strongly suppressed, is revisited, correcting a numerical error. New estimates are given, adopting the Collins functions recently extracted from semi-inclusive deep inelastic scattering and $e^{+}{e}^{-}$ data, and phenomenological consequences are discussed.