The Bousso-Polchinski landscape is a proposal for solving the cosmological constant problem. The solution requires counting the states in a very thin shell in flux space. We find an exact formula for this counting problem which has two simple asymptotic regimes, one of them being the method of counting low $\Lambda$ states given originally by Bousso and Polchinski. We finally give some applications of the extended formula: a robust property of the landscape which can be identified with an effective occupation number, an estimator for the minimum cosmological constant, and a possible influence on the Kachru-Kallosh-Linde-Trivedi stabilization mechanism.

We show that a supersymmetric axion model naturally induces a hybrid inflation with the waterfall field identified as a Peccei-Quinn scalar. The Peccei-Quinn scale is predicted to be around ${10}^{15}\mathrm{GeV}$ for reproducing the large-scale density perturbation of the Universe. After the built-in late-time entropy-production process, the axion becomes a dark matter candidate. Several cosmological implications are discussed.

We calculate the relic density of stau at the big-bang nucleosynthesis era in the coannihilation scenario of the minimal supersymmetric standard model. In this scenario, stau can be long lived and have significance in the remediation of light elements abundances. The freeze-out of stau is corroborated by solving the Boltzmann equation numerically, and the parameter dependence of the relic density is investigated. The possibility of solving the ${}^7\mathrm{Li}$ problem is examined by taking account into the long-lived stau. By adopting an observational value of ${}^7\mathrm{Li}$ in [J. Meléndez and I. Ramírez, Astrophys. J. 615, L33 (2004).], we get minimal supersymmetric standard model parameter space in which abundances of both dark matter and all of the light elements are reproduced in accordance with observations. We also address the influence of intergenerational mixing on our calculation.

Many extensions of the standard model predict superweakly interacting particles, which typically have to decay before big bang nucleosynthesis. The entropy produced in the decays may help to reconcile thermal leptogenesis and big bang nucleosynthesis in scenarios with gravitino dark matter, which is usually difficult due to late decays of the next-to-lightest supersymmetric particle spoiling the predictions of big bang nucleosynthesis. We study this possibility for a general neutralino next-to-lightest supersymmetric particle. We elaborate general properties of the scenario and strong constraints on the entropy-producing particle. As an example, we consider the saxion from the axion multiplet and show that, while enabling a solution of the strong $CP$ problem, it can also produce a suitable amount of entropy.

The mass of the triply-heavy baryon ${\Omega }_{bbb}$ is calculated in lattice QCD with $2+1$ flavors of light sea quarks. The $b$ quark is implemented with improved lattice nonrelativistic QCD. Gauge field ensembles from both the RBC/UKQCD and MILC collaborations with lattice spacings in the range from 0.08 fm to 0.12 fm are used. The final result for the ${\Omega }_{bbb}$ mass, which includes an electrostatic correction, is $14.371\pm {0.004}_{\mathrm{stat}}\pm {0.011}_{\mathrm{syst}}\pm {0.001}_{\exp }\mathrm{GeV}$. The hyperfine splitting between the physical $J=3/2$ state and a fictitious $J=1/2$ state is also calculated.

We have investigated the fluctuations and the higher order susceptibilities of quark number, isospin number, electric charge, and strangeness at vanishing chemical potential for the $2+1$ flavor Polyakov loop extended Nambu–Jona-Lasinio model. The calculations are performed for the bound effective potential in the quark sector requiring up to eight quark interaction terms. These have been contrasted to the lattice results which currently have somewhat heavier quarks in the light flavor sector. The results show sufficient qualitative agreement. For comparison we also present the results obtained with the conventional effective potential containing up to six quark interaction terms.

We provide a comparative study of the Higgs boson mass measurements based on two approaches to the dileptonic decay of $W$ bosons produced by the Higgs boson decay, one using the kinematic variable $M_T^{\mathrm{true}}$ and the other using the $M_{T2}$-assisted on-shell reconstruction of the invisible neutrino momenta. We find that these two approaches can determine the Higgs boson mass with a similar accuracy for both of the two main production mechanisms of the SM Higgs boson at the LHC, i.e. the gluon-gluon fusion and the weak vector boson fusion. We also notice that the Higgs signal distribution for the gluon-gluon fusion becomes narrower under the $M_{T2}$ cut, while the corresponding background distribution becomes flatter, indicating that one might be able to reduce the systematic uncertainties of mass measurement with an appropriate $M_{T2}$ cut.

We report on the search for Lorentz-violating sidereal variations of the frequency difference of colocated spin species while the Earth and hence the laboratory reference frame rotates with respect to a relic background field. The comagnetometer used is based on the detection of freely precessing nuclear spins from polarized ${}^3\mathrm{He}$ and ${}^{129}\mathrm{Xe}$ gas samples using SQUIDs as low-noise magnetic flux detectors. As result we can determine the limit for the equatorial component of the background field interacting with the spin of the bound neutron to be ${\tilde{b}}_{\perp }^n<3.7·{10}^{-32}\mathrm{GeV}$ (95% C.L.).

We comment on Weinberg’s interesting analysis of asymptotically safe inflation [S. Weinberg, Phys. Rev. D 81, 083535 (2010).]. We find that even if the gravity theory exhibits an ultraviolet fixed point, the energy scale during inflation is way too low to drive the theory close to the fixed point value. We choose the specific renormalization group flow away from the fixed point towards the infrared region that reproduces the Newton’s constant and today’s cosmological constant. We follow this renormalization group flow path to scales below the Planck scale to study the stability of the inflationary scenario. Again, we find that some fine-tuning is necessary to get enough $e$ folds of inflation in the asymptotically safe inflationary scenario.

After the discovery of the $s$-wave and $p$-wave holographic superconductors, holographic models of the $d$-wave superconductor have also been constructed recently. We study analytically the perturbation of the dual gravity theory to calculate the superconducting coherence length $\xi$ of the $d$-wave holographic superconductor near the superconducting phase transition point. The superconducting coherence length $\xi$ diverges as $(1-T/T_c{)}^{-1/2}$ near the critical temperature $T_c$. We also obtain the magnetic penetration depth $\lambda \propto (T_c-T{)}^{-1/2}$ by adding a small external homogeneous magnetic field. The results agree with the $s$-wave and $p$-wave models, which are also the same as the Ginzburg-Landau theory.

We perform a systematic study of stationary sphaleron-antisphaleron systems of Weinberg-Salam theory at the physical value of the weak mixing angle. These systems include rotating sphaleron-antisphaleron pairs, chains, and vortex rings. We show that the angular momentum of these solutions is proportional to their electric charge. We study the dependence of their energy and magnetic moment on their angular momentum. We also investigate the influence of their angular momentum on their local properties, in particular, on their energy density and on the node structure of their Higgs field configuration. Furthermore, we discuss the equilibrium condition for these solutions.

We examine the toroidal oscillations on the slowly rotating relativistic stars in tensor-vector-scalar (TeVeS) theory with the Cowling approximation. As a result, we find that perturbation equations describing the toroidal oscillations are same equation form as in general relativity (GR). Although the frequencies of toroidal oscillations in TeVeS are not so different from those in GR, the momentum inertia depends strongly on the gravitational theory. Thus, observing the frequencies of toroidal oscillations and momentum inertia with high accuracy might reveal the gravitational theory in the strong-field regime.

We derive the cosmological big bounce scenario from the dipole approximation of loop quantum gravity. We show that a nonsingular evolution takes place for any matter field and that, by considering a massless scalar field as a relational clock for the dynamics, the semiclassical proprieties of a large class of initial states are preserved on the other side of the bounce. This model thus enhances the relation between loop quantum cosmology and the full theory.

We demonstrate the classical stability of the BTZ black hole within the context of topologically massive gravity. The linearized perturbation equations can be solved exactly in this case. By choosing standard boundary conditions appropriate to the stability problem, we demonstrate the absence of modes which grow in time, for all values of the Chern-Simons coupling.

Detection of high-energy ($\gtrsim 100\mathrm{MeV}$) $\gamma$ rays by the Fermi Large Area Telescope from a nova in the symbiotic binary system V407 Cygni has opened the possibility of high-energy neutrino detection from this type of source. A thermonuclear explosion on the white dwarf surface sets off a nova shell in motion that expands and slows down in a dense surrounding medium provided by the red giant companion. Particles are accelerated in the shocks of the shell and interact with the surrounding medium to produce observed $\gamma$ rays. We show that proton-proton interaction, which is most likely responsible for producing $\gamma$ rays via neutral pion decay, produces $\gtrsim 0.1\mathrm{GeV}$ neutrinos that can be detected by the current and future experiments at $\gtrsim 10\mathrm{GeV}$.

Tidal torques acting on a gaseous accretion disk around a binary black hole can create a gap in the disk near the orbital radius. At late times, when the binary inspiral time scale due to gravitational wave emission becomes shorter than the viscous time scale in the disk, the binary decouples from the disk and eventually merges. Prior to decoupling the balance between tidal and viscous torques drives the disk to a quasistationary equilibrium state, perturbed slightly by small amplitude, spiral density waves emanating from the edges of the gap. We consider a black hole binary with a companion of smaller mass and construct a simple Newtonian model for a geometrically thin, Keplerian disk in the orbital plane of the binary. We solve the disk evolution equations in the steady state to determine the quasistationary, (orbit-averaged) surface density profile prior to decoupling. We use our solution, which is analytic up to simple quadratures, to compute the electromagnetic flux and approximate radiation spectrum during this epoch. A single nondimensional parameter $\tilde{g}$, equal to the ratio of the tidal to viscous torque at the orbital radius, determines the disk structure, including the surface density profile, the extent of the gap, the existence of an inner disk, and the accretion rate. The solution reduces to the Shakura-Sunyaev profile for a stationary accretion disk around a single black hole in the limit of small $\tilde{g}$. Our solution may be useful for choosing physical parameters and setting up quasistationary disk initial data for detailed numerical simulations that begin prior to decoupling and track the subsequent evolution of a black hole binary-disk system.

In little Randall-Sundrum models, the bulk couplings of the radion to massless gauge fields can yield a greatly enhanced diphoton signal at hadron colliders. We examine the implications of the Tevatron data for the little radion and also show that the 7 TeV run at the Large Hadron Collider will have an impressive reach in this channel. The diphoton signal is crucial in the search for a light radion, or the dual dilaton, and can potentially probe the ultraviolet scale of the theory.

We present a high precision lattice calculation of the average up/down, strange, and charm quark masses performed with $N_f=2$ twisted-mass Wilson fermions. The analysis includes data at four values of the lattice spacing and pion masses as low as $\simeq 270\mathrm{MeV}$, allowing for accurate continuum limit and chiral extrapolation. The strange and charm masses are extracted by using several methods, based on different observables: the kaon and the ${\eta }_s$ meson for the strange quark and the $D$, $D_s$, and ${\eta }_c$ mesons for the charm. The quark mass renormalization is carried out nonperturbatively using the regularization independent momentum–subtraction renormalization (RI-MOM) method. The results for the quark masses in the modified minimal subtraction ($\overline{\mathrm{MS}}$) scheme read: ${\overline{m}}_{ud}(2\mathrm{GeV})=3.6(2)\mathrm{MeV}$, ${\overline{m}}_s(2\mathrm{GeV})=95(6)\mathrm{MeV}$, and ${\overline{m}}_c({\overline{m}}_c)=1.28(4)\mathrm{GeV}$. We also obtain the ratios $m_s/m_{ud}=27.3(9)$ and $m_c/m_s=12.0(3)$.

Recent evidence for a $CP$ violating asymmetry in the semileptonic decays of $B_s$ mesons cannot be accommodated within the standard model. Such an asymmetry can be explained by new physics contributions to $\Delta B=2$ components of either the mass matrix or the decay matrix. We show that mixing with a hidden pseudoscalar meson with a mass around 5 GeV can result in a new $CP$ violating contribution to the mixing and can resolve several anomalies in this system including the width difference, the average width and the charge asymmetry. We also discuss the effects of the hidden meson on other $b$ physics observables, and present viable decay modes for the hidden meson. We make predictions for new decay channels of $B$ hadrons, which can be tested at the Tevatron, the LHC and B-factories.

We have studied the one-meson radiative tau decays ${\tau }^{-}\to {\nu }_{\tau }{\pi }^{-}(K^{-})\gamma$, computing the structure-dependent contributions within a Lagrangian approach based on the large-$N_C$ limit of QCD that ensures the proper low-energy limit dictated by chiral symmetry. Upon imposing the short-distance QCD constraints to the form factors, we are able to predict the structure-dependent radiation without any free parameter and, therefore, the relevant observables for the decay ${\tau }^{-}\to {\nu }_{\tau }{\pi }^{-}\gamma$: the photon energy spectrum, the invariant mass spectrum of the meson-photon system, and the integrated decay rate. We also discuss the remaining uncertainties in these observables for the ${\tau }^{-}\to {\nu }_{\tau }{K}^{-}\gamma$ decay. According to our results, the present facilities could detect these rare decays for the first time in the near future, allowing for a stringent test of our predictions.