We consider the time evolution of two entropylike quantities, the holographic entanglement entropy and causal holographic information, in a model of holographic thermalization dual to the gravitational collapse of a thin planar shell. Unlike earlier calculations valid in different limits, we perform a full treatment of the dynamics of the system, varying both the shell’s equation of state and initial position. In all cases considered, we find that between an early period related to the acceleration of the shell and a late epoch of saturation towards the thermal limit, the entanglement entropy exhibits universal linear growth in time in accordance with the prediction of Liu and Suh. As intermediate steps of our analysis, we explicitly construct a coordinate system continuous at the location of an infinitely thin shell and derive matching conditions for geodesics and extremal surfaces traversing this region.

Robust gauge conditions are critically important to the stability and accuracy of numerical relativity (NR) simulations involving compact objects. Most of the NR community use the highly robust—though decade-old—moving-puncture (MP) gauge conditions for such simulations. It has been argued that in binary black hole evolutions adopting this gauge, noise generated near adaptive-mesh-refinement (AMR) boundaries does not converge away cleanly with increasing resolution, severely limiting gravitational waveform accuracy at computationally feasible resolutions. We link this noise to a sharp (short-wavelength), initial outgoing gauge wave crossing into progressively lower resolution AMR grids and present improvements to the standard MP gauge conditions that focus on stretching, smoothing, and more rapidly settling this outgoing wave. Our best gauge choice greatly reduces gravitational waveform noise during inspiral, yielding less fluctuation in convergence order and $\sim 40\%$ lower waveform phase and amplitude errors at typical resolutions. Noise in other physical quantities of interest is also reduced, and constraint violations drop by more than an order of magnitude. We expect these improvements will carry over to simulations of all types of compact binary systems, as well as other $N+1$ formulations of gravity for which MP-like gauge conditions can be chosen.

In this paper, we present a novel method of extracting the couplings of a heavy particle to the Standard Model states. Contrary to the usual discovery process which involves studying the on-shell production, we look at regions away from resonance to take advantage of the simple scaling of the cross-section with the couplings. We illustrate the procedure with the example of a heavy quark.

Coherent scattering of solar, atmospheric, and diffuse supernovae neutrinos creates an irreducible background for direct dark matter experiments with sensitivities to WIMP-nucleon spin-independent scattering cross sections of $10^{-46}–{10}^{-48}{\mathrm{cm}}^2$, depending on the WIMP mass. Even if one could eliminate all other backgrounds, this “neutrino floor” will limit future experiments with projected sensitivities to cross sections as small as ${10}^{-48}{\mathrm{cm}}^2$. Direction-sensitive detectors have the potential to study dark matter beyond the neutrino bound by fitting event distributions in multiple dimensions: recoil kinetic energy, recoil track angle with respect to the sun, and event time. This work quantitatively explores the impact of direction sensitivity on the neutrino bound in dark matter direct detection.

We investigate the di-Higgs events through $Z_H$-pair production at the CERN Large Hadron Collider including the pure next-to-leading order (NLO) QCD correction and the $gg$-fusion contribution in the framework of the littlest Higgs model with $T$ parity. We employ the diagram subtraction scheme in the QCD NLO calculations to avoid double counting and keep the convergence of the perturbative QCD description for the $Z_H$-pair production. We investigate the dependence of the leading order and QCD corrected integrated cross sections on the renormalization/factorization scale, and find that the total QCD corrections slightly reduce the scale uncertainty in the plotted range. By considering the subsequent decays of the intermediately produced $Z_H$ bosons and adopting the exclusive four-$b$-jet event selection criterion, the QCD correction provides considerable enhancement of the kinematic distributions for final decay products. We find that it is possible to select the signature of the $Z_H$-pair production from possible standard model background by taking proper kinematic cuts.

It is suggested that there is an underlying symmetry which relates the quark and lepton sectors. Namely, among the mixing matrix elements of Cabibbo-Kobayashi-Maskawa for quarks and Pontecorvo-Maki-Nakawaga-Sakata for leptons there exist complementarity relations at a high energy scale (such as the seesaw or even the grand unification theory scales). We assume that the relations would remain during the matrix elements running down to the electroweak scale. Observable breaking of the rational relation is attributed to the existence of sterile neutrinos that mix with the active neutrino to result in the observable Pontecorvo-Maki-Nakawaga-Sakata matrix. We show that involvement of a sterile in the ($3+1$) model induces that $|U_{e4}{|}^2=0.040$, $|U_{\mu 4}{|}^2=0.009$, and ${\sin }^{2}2\alpha =0.067$. We also find a new self-complementarity ${\vartheta }_{12}+{\vartheta }_{23}+{\vartheta }_{13}+\alpha \approx 90°$. The numbers are generally consistent with those obtained by fitting recent measurements, especially in this scenario, to the existence of a sterile neutrino that does not upset the LEP data; i.e., the number of neutrino types is very close to 3.

The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to dielectron or dimuon final states. Results are presented from an analysis of proton-proton ($pp$) collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$ in the dimuon channel. A narrow resonance with Standard Model $Z$ couplings to fermions is excluded at 95% confidence level for masses less than 2.79 TeV in the dielectron channel, 2.53 TeV in the dimuon channel, and 2.90 TeV in the two channels combined. Limits on other model interpretations are also presented, including a grand-unification model based on the $E_6$ gauge group, $Z^{*}$ bosons, minimal $Z\prime$ models, a spin-2 graviton excitation from Randall-Sundrum models, quantum black holes, and a minimal walking technicolor model with a composite Higgs boson.

The large branching ratios for pure annihilation ${\overline{B}}_s^0\to {\pi }^{+}{\pi }^{-}$ and ${\overline{B}}_d^0\to K^{+}{K}^{-}$ decays reported by CDF and LHCb collaborations recently and the so-called $\pi K$ and $\pi \pi$ puzzles indicate that spectator scattering and annihilation contributions are important to the penguin-dominated, color-suppressed tree dominated, and pure annihilation nonleptonic $B$ decays. Combining the available experimental data for $B_{u,d}\to \pi \pi$, $\pi K$ and $K\overline{K}$ decays, we do a global fit on the spectator scattering and annihilation parameters $X_H({\rho }_H,{\varphi }_H)$, $X_A^i({\rho }_A^i,{\varphi }_A^i)$ and $X_A^f({\rho }_A^f,{\varphi }_A^f)$, which are used to parametrize the end point singularity in amplitudes of spectator scattering, nonfactorizable and factorizable annihilation topologies within the QCD factorization framework, in three scenarios for different purpose. Numerically, in Scenario II, we get $({\rho }_A^i,{\varphi }_A^i{[}^{\circ }])=(2.88_{-1.30}^{+1.52},-103_{-40}^{+33})$ and $({\rho }_A^f,{\varphi }_A^f{[}^{\circ }])=(1.21_{-0.25}^{+0.22},-40_{-8}^{+12})$ at the 68% confidence level, which are mainly demanded by resolving the $\pi K$ puzzle and confirm the presupposition that $X_A^i\ne X_A^f$. In addition, correspondingly, the $B$-meson wave function parameter ${\lambda }_B$ is also fitted to be $0.18_{-0.08}^{+0.11}\mathrm{MeV}$, which plays an important role for resolving both $\pi K$ and $\pi \pi$ puzzles. With the fitted parameters, the QCD factorization results for observables of $B_{u,d}\to \pi \pi$, $\pi K$ and $K\overline{K}$ decays are in good agreement with experimental measurements. Many more experimental and theoretical efforts are expected to understand the underlying QCD dynamics of spectator scattering and annihilation contributions.

We develop an approach for solving the string equations of motion and Virasoro constraints in any background that has some (unfixed) number of commuting Killing vector fields. It is based on a specific ansatz for the string embedding. We apply the above-mentioned approach for strings moving in ${\mathrm{AdS}}_3\times S^3\times T^4$ with a 2-form NS-NS $B$-field. We succeeded to find solutions for a large class of string configurations on this background. In particular, we derive dyonic giant magnon solutions in the $R_t\times S^3$ subspace and obtain the leading finite-size correction to the dispersion relation.

We consider whether an external electric field may cause the pair production of open strings in a type IIA plane-wave background. The boundary states of D-branes with condensates are constructed in the Green-Schwarz formulation of superstring theory with the light-cone gauge. The cylinder diagrams are computed with massive theta functions. Although the value of the electric field is bounded by the upper value, there is no pole in the amplitudes and it indicates that no pair production occurs in the plane-wave background. This result would be universal for a class of plane-wave backgrounds.

We consider a scenario in which our $(3+1)$-dim universe is actually a dense stack of multiple parallel $(2+1)$-dim branes. For this purpose, we generalize the Dvali-Gabadadze-Porrati model to a multibrane case. We solve for the propagation of the scalar field and gravity in this setup. At short distances (high momenta) along the branes interactions follow the $(2+1)$-dim laws, while at large distances (low momenta) interactions follow the usual $(3+1)$-dim laws. This feature is inherited from the original Dvali-Gabadadze-Porrati model. In the direction perpendicular to the brane, we show that interactions become $(3+1)$-dim at low momenta which are unable to resolve the interbrane separation. Thus, this is one of the explicit constructs of the “vanishing dimensions” scenario where high energy physics appears to be lower dimensional rather than higher dimensional.

The gravitational properties of astrophysical objects depend sensitively on their internal structure. In Newtonian theory, the gravitational potential of a rotating star can be fully described by an infinite number of multipole moments of its mass distribution. Recently, this infinite number of moments for uniformly-rotating stars were shown semianalytically to be expressible in terms of just the first three: the mass, the spin, and the quadrupole moment of the star. The relations between the various lower multipole moments were additionally shown to depend weakly on the equation of state, when considering neutron stars and assuming single polytropic equations of state. Here we extend this result in two ways. First, we show that the universality also holds for realistic equations of state, thus relaxing the need to use single polytropes. Second, we derive purely analytical universal relations by perturbing the equations of structure about an $n=0$ polytrope that reproduce semianalytic results to $\mathcal{O}(1\%)$. We also find that the linear-order perturbation vanishes in some cases, which provides further evidence and a deeper understanding of the universality.

Inflation is the leading theory to describe elegantly the initial conditions that led to structure formation in our Universe. In this paper, we present a novel phenomenological fit to the Planck, WMAP polarization (WP) and the BICEP2 data sets using an alternative parametrization. Instead of starting from inflationary potentials and computing the inflationary observables, we use a phenomenological parametrization due to Mukhanov, describing inflation by an effective equation of state, in terms of the number of $e$-folds and two phenomenological parameters $\alpha$ and $\beta$. Within such a parametrization, which captures the different inflationary models in a model-independent way, the values of the scalar spectral index $n_s$, its running and the tensor-to-scalar ratio $r$ are predicted, given a set of parameters $(\alpha ,\beta )$. We perform a Markov Chain Monte Carlo analysis of these parameters, and we show that the combined analysis of Planck and WP data favors the Starobinsky and Higgs inflation scenarios. Assuming that the BICEP2 signal is not entirely due to foregrounds, the addition of this last data set prefers instead the ${\varphi }^2$ chaotic models. The constraint we get from Planck and WP data alone on the derived tensor-to-scalar ratio is $r<0.18$ at 95% C.L., value which is consistent with the one quoted from the BICEP2 Collaboration analysis, $r={0.16}_{-0.05}^{+0-06}$, after foreground subtraction. This is not necessarily at odds with the $2\sigma$ tension found between Planck and BICEP2 measurements when analyzing data in terms of the usual $n_s$ and $r$ parameters, given that the parametrization used here, for the preferred value $n_s\simeq 0.96$, allows only for a restricted parameter space in the usual $(n_s,r)$ plane.

We compare four different methods that can be used to analyze the type Ia supernovae (SnIa) data, ie to use piecewise-constant functions in terms of: the dark energy equation of state $w(z)$, the deceleration parameter $q(z)$, the Hubble parameter $H(z)$ and finally the luminosity distance $d_L$. These four quantities cover all aspects of the accelerating Universe, i.e. the phenomenological properties of dark energy, the expansion rate (first and second derivatives) of the Universe and the observations themselves. For the first two cases we also perform principal component analysis (PCA) so as to decorrelate the parameters, while for the last two cases we use novel analytic expressions to find the best-fit parameters. In order to test the methods we create mock SnIa data (2000 points, uniform in redshift $z\in [0,1.5]$) for three fiducial cosmologies: the cosmological constant model ($\mathrm{\Lambda }\mathrm{CDM}$), a linear expansion of the dark energy equation of state parameter $w(a)=w_0+w_a(1-a)$ and the Hu-Sawicki $f(R)$ model. We find that if we focus on the two mainstream approaches for the PCA, i.e. $w(z)$ and $q(z)$, then the best piecewise-constant scheme is always $w(z)$. Finally, to our knowledge the piecewise-constant method for $H(z)$ is new in the literature, while for the rest three methods we present several new analytic expressions.

We report the first lattice QCD calculation of the form factors for the standard model tree-level decay $B_s\to K\ell \nu$. In combination with future measurement, this calculation will provide an alternative exclusive semileptonic determination of $|V_{ub}|$. We compare our results with previous model calculations, make predictions for differential decay rates and branching fractions, and predict the ratio of differential branching fractions between $B_s\to K\tau \nu$ and $B_s\to K\mu \nu$. We also present standard model predictions for differential decay rate forward-backward asymmetries and polarization fractions and calculate potentially useful ratios of $B_s\to K$ form factors with those of the fictitious $B_s\to {\eta }_s$ decay. Our lattice simulations utilize nonrelativistic QCD $b$ and highly improved staggered light quarks on a subset of the MILC Collaboration $2+1$ asqtad gauge configurations, including two lattice spacings and a range of light quark masses.

The drag and diffusion coefficients of the ${\mathrm{\Lambda }}_c(2286\mathrm{MeV})$ have been evaluated in the hadronic medium which is expected to be formed in the later stages of the evolving fireball produced in heavy ion collisions at RHIC and LHC energies. The interactions between the ${\mathrm{\Lambda }}_c$ and the hadrons in the medium have been derived from an effective hadronic Lagrangian, as well as from the scattering lengths obtained in the framework of heavy baryon chiral perturbation theory ($\mathrm{HB}\chi \mathrm{PT}$). In both the approaches, the magnitude of the transport coefficients turn out to be significant. A larger value is obtained in the former approach with respect to the latter. Significant values of the coefficients indicate a substantial amount of interaction of the ${\mathrm{\Lambda }}_c$ with the hadronic thermal bath. Furthermore, the transport coefficients of the ${\mathrm{\Lambda }}_c$ are found to be different from the transport coefficients of the $D$ meson. The present study indicates that the hadronic medium has a significant impact on the ${\mathrm{\Lambda }}_c/D$ ratio in heavy ion collisions.

The holographic entanglement entropy of an infinite strip subsystem on the asymptotic anti–de Sitter (AdS) boundary is used as a probe to study the thermodynamic instabilities of planar $R$-charged black holes (or their dual field theories). We focus on the single-charge AdS black holes in $D=5$, which correspond to spinning $D3$-branes with one nonvanishing angular momentum. Our results show that the holographic entanglement entropy indeed exhibits the thermodynamic instability associated with the divergence of the specific heat. When the width of the strip is large enough, the finite part of the holographic entanglement entropy as a function of the temperature resembles the thermal entropy, as is expected. As the width becomes smaller, however, the two entropies behave differently. In particular, there exists a critical value for the width of the strip, below which the finite part of the holographic entanglement entropy as a function of the temperature develops a self-intersection. We also find similar behavior in the single-charge black holes in $D=4$ and 7.

Chiral magnetic effect and chiral vortical effect are parity odd transport phenomena originating from chiral anomaly, and have generalizations to all even dimensional space-time higher than four dimensions. We attempt to compute the associated P-odd retarded response functions in the weak coupling limit of chiral fermion theory in all even dimensions, using the diagrammatic technique of real-time perturbation theory. We also clarify the necessary Kubo formula relating the computed P-odd retarded correlation functions and the associated anomalous transport coefficients. We speculate on the 8-fold classification of topological phases.

One of the greatest impediments to extracting useful information from high luminosity hadron-collider data is radiation from secondary collisions (i.e. pileup) which can overlap with that of the primary interaction. In this paper we introduce a simple jet-substructure technique termed cleansing which can consistently correct for large amounts of pileup in an observable independent way. Cleansing works at the subjet level, combining tracker and calorimeter-based data to reconstruct the pileup-free primary interaction. The technique can be used on its own, with various degrees of sophistication, or in concert with jet grooming. We apply cleansing to both kinematic and jet shape reconstruction, finding in all cases a marked improvement over previous methods both in the correlation of the cleansed data with uncontaminated results and in measures like $S/\sqrt{B}$. Cleansing should improve the sensitivity of new-physics searches at high luminosity and could also aid in the comparison of precision QCD calculations to collider data.