Indications for a $\gamma$-ray line(s) signal toward the Galactic Center at an energy of about 130 GeV have been recently presented. While dark matter annihilations are a viable candidate for this signal, it is generally expected that such a flux would be correlated to a $\gamma$-ray component with continuum energy spectrum due to dark matter pair annihilating into other Standard Model particles. We use the $\gamma$-ray data from the inner $10°\times 10°$ window to derive limits for a variety of dark matter annihilation final states. Extending the window of observation, we discuss bounds on the morphological shape of a dark matter signal associated to the line, applying both standard templates for the dark matter profile, such as an Einasto or a Navarro-Frenk-White profile, and introducing a new more general parametrization.

In this work we propose an alternative scheme for an emergent universe scenario where the universe is initially in a static state supported by a scalar field located in a false vacuum. The universe begins to evolve when, by quantum tunneling, the scalar field decays into a state of true vacuum. The emergent universe models are interesting since they provide specific examples of nonsingular inflationary universes.

The kinetic decoupling of dark matter (DM) from the primordial plasma sets the size of the first and smallest DM halos. Studies of the DM kinetic decoupling have hitherto mostly neglected interactions between the DM and the quarks in the plasma. Here we illustrate their importance using two frameworks: a version of the minimal supersymmetric standard model and an effective field theory with effective DM-quark interaction operators. We connect particle physics and astrophysics obtaining bounds on the smallest DM halo size from collider data and from direct DM search experiments. In the Minimal Supersymmetric Standard Model framework, adding DM-quark interactions to DM-lepton interactions more than doubles the smallest DM halo mass in a wide range of the supersymmetric parameter space.

The ultrarelativistic shock layer around the triangle prism is numerically analyzed using the relativistic Boltzmann equation to investigate the dissipation process under two types of ultrarelativistic limits: namely, the Lorentz contraction limit, in which the uniform flow velocity approximates to the speed of light, and the thermally relativistic limit, in which the temperature of the uniform flow approximates to infinity. The relativistic Boltzmann equation is numerically solved using the direct simulation Monte Carlo method. We discuss dissipation process in the flow field by focusing on profiles of the dynamic pressure and heat flux along the stagnation streamline under the Lorentz contraction limit or the thermally relativistic limit. Our numerical results confirm that profiles of the dynamic pressure and heat flux along the stagnation streamline strongly depend on the Lorentz contraction and thermally relativistic effects under their ultrarelativistic limits, as predicted by Chapman-Enskog expansion on the basis of the generic Knudsen number.

In dark matter (DM) models, the production of a $\gamma$ line (or of a “box-shaped” $\gamma$-ray spectrum) from DM annihilation proceeds in general from a loop diagram involving a heavy charged particle. If the charged particle in the loop carries also a color charge, this leads inevitably to DM annihilation to gluons, with a naturally larger rate. We consider a scenario in which DM candidates annihilate dominantly into gluon pairs, and determine (as far as possible, model-independent) constraints from a variety of observables: (a) the dark matter relic density, (b) the production of antiprotons, (c) DM direct detection and (d) gluon-gluon fusion processes at LHC. Among other things, we show that this scenario together with the recent claim for a possible $\gamma$ line from the Galactic center in the Fermi-LAT data, leads to a relic abundance of DM that may be naturally close to the cosmological observations.

Models of inhomogeneous universes constructed with exact solutions of Einstein’s general relativity have been proposed in the literature with the aim of reproducing the cosmological data without any need for a dark energy component. Besides large scale inhomogeneity models spherically symmetric around the observer, Swiss-cheese models have also been studied. Among them, Swiss cheeses where the inhomogeneous patches are modeled by different particular Szekeres solutions have been used for reproducing the apparent dimming of the type Ia supernovae. However, the problem of fitting such models to the type Ia supernovae data is completely degenerate and we need other constraints to fully characterize them. One of the tests which is known to be able to discriminate between different cosmological models is the redshift drift. This drift has already been calculated by different authors for Lemaître-Tolman-Bondi models. We compute it here for one particular axially symmetric quasispherical Szekeres Swiss cheese which has previously been shown to reproduce to a good accuracy the type Ia supernovae data, and we compare the results to the drift in the $\Lambda \mathrm{CDM}$ model and in some Lemaître-Tolman-Bondi models that can be found in the literature. We show that it is a good discriminator between them. Then, we discuss our model’s remaining degrees of freedom and propose a recipe to fully constrain them.

We calculate the particle production rate in an expanding universe with a three-torus topology. We discuss also the complete evolution of the size of such a universe. The energy density of particles created through the nonzero modes is computed for selected masses. The unique contribution of the zero mode and its properties are also analyzed.

We study a ghost-free model of a massive vector curvaton proposed in the literature, where the quick decrease of the vector background expectation value is avoided by a suitable choice of kinetic and mass functions. The curvaton perturbations of this model have been so far computed assuming that these functions are external classical quantities, and it was found that some special time evolution of these functions leads to scale-invariant and statistically isotropic perturbations of the vector curvaton. However, external functions should be understood as originating from the expectation value of some additional field. Since these functions need to present a nontrivial evolution during inflation, the field cannot be trivially integrated out, and in particular, its perturbations need to be included in the computation. We do so in a minimal implementation of the mechanism, where the additional field is identified with the inflaton. We show that, except for a narrow window of model parameters, the interaction with this field generally causes the curvature perturbations to violate statistical isotropy beyond the observational limit.

In recent years several approaches to quantum gravity have found evidence for a scale dependent spectral dimension of space-time varying from four at large scales to two at small scales of order of the Planck length. The first evidence came from numerical results on four-dimensional causal dynamical triangulations (CDT) [Ambjørn et al., Phys. Rev. Lett. 95, 171301 (2005)]. Since then little progress has been made in analytically understanding the numerical results coming from the CDT approach and showing that they remain valid when taking the continuum limit. Here we argue that the spectral dimension can be determined from a model with fewer degrees of freedom obtained from the CDTs by radial reduction. In the resulting toy model we can take the continuum limit analytically and obtain a scale dependent spectral dimension varying from four to two with scale and having functional behavior exactly of the form which was conjectured on the basis of the numerical results.

We examine a supersymmetric explanation for the anomalously high forward-backward asymmetry in top pair production measured by CDF and D0. We suppose that it is due to the $t$-channel exchange of a right-handed sbottom which couples to $d_R$ and $t_R$, as is present in the $R$-parity violating minimal supersymmetric standard model. We show that all Tevatron and LHC experiments’ $t\overline{t}$ constraints may be respected for a sbottom mass between 300 and 1200 GeV, and a large Yukawa coupling $>2.2$, yielding $A_{\mathrm{FB}}$ up to 0.18. The non-Standard Model contribution to the LHC charge asymmetry parameter is $\Delta A_C^y=0.017–0.045$, small enough to be consistent with current measurements but nonzero and positive, allowing for LHC confirmation in the future within $20{\mathrm{fb}}^{-1}$. A small additional contribution to the LHC $t\overline{t}$ production cross section is also predicted, allowing a further test. We estimate that $10{\mathrm{fb}}^{-1}$ of LHC luminosity would be sufficient to rule out the proposal to 95% confidence level, if the measurements of the $t\overline{t}$ cross section turn out to be centered on the Standard Model prediction.

The recent discovery of a 125 GeV Higgs, as well as the lack of any positive findings in searches for supersymmetry, has renewed interest in both the supersymmetric Higgs sector and fine-tuning (FT). Here, we continue our study of the phenomenological minimal supersymmetric standard model (pMSSM), discussing the light Higgs and FT within the context of two sets of previously generated pMSSM models. We find an abundance of models with experimentally favored Higgs masses and couplings. We investigate the decay modes of the light Higgs in these models, finding strong correlations between many final states. We then examine the degree of FT, considering contributions from each of the pMSSM parameters at up to next-to-leading log order. In particular, we examine the FT implications for our model sets that arise from the discovery of a 125 GeV Higgs. Finally, we investigate a small subset of models with low FT and a light Higgs near 125 GeV, describing the common features of such models. We generically find a light stop and bottom with complex decay patterns into a set of light electroweak gauginos, which will make their discovery more challenging and may require novel search techniques.

We have revisited the prospects of supersymmetry searches at the LHC with 7 TeV energy along with the prediction of the discovery potential at 8 TeV energy assuming an integrated luminosity $5{\mathrm{fb}}^{-1}$ and $20{\mathrm{fb}}^{-1}$ with minimal supergravity/minimal supersymmetric standard model as a model framework. We discuss further optimization of our selection strategy, which is based on the hadronic event shape variables. Evaluating the standard model backgrounds and signal rates in detail, we predict the discovery reach in the $m_0-m_{1/2}$ plane for 7 TeV with $5{\mathrm{fb}}^{-1}$ luminosity. We also present the discovery reach for 8 TeV energy with an integrated luminosity $5{\mathrm{fb}}^{-1}$ and $20{\mathrm{fb}}^{-1}$. A comparison is made between our results and the exclusion plots obtained by CMS and ATLAS. Finally, discovery reach in the gluino and squark mass plane at the 7 TeV and 8 TeV energy is also presented.

Using precise lattice QCD computations of the baryon spectrum, we present the first direct evidence for the presence of contributions to the baryon masses which are nonanalytic in the light quark masses, contributions which are often denoted chiral logarithms. It is demonstrated that the $SU(3)$ flavor-singlet mass combination suffers the most severe convergence issues. The flavor-octet baryon mass splittings, which are corrected by chiral logarithms at next-to-leading order in $SU(3)$ chiral perturbation theory, yield baryon-pion axial coupling constants $D$, $F$, $C$ and $H$ consistent with QCD values, the first evidence of chiral logarithms in the baryon spectrum. The Gell-Mann–Okubo relation, a flavor-$\mathbf{27}$ baryon mass splitting, which is dominated by chiral corrections from light quark masses, provides further evidence for the presence of nonanalytic light quark mass dependence in the baryon spectrum; we simultaneously find the Gell-Mann–Okubo relation to be inconsistent with the first few terms in a Taylor expansion in $m_s-m_l$, which must be valid for small values of this $SU(3)$ breaking parameter. Additional, more definitive tests of $SU(3)$ chiral perturbation theory will become possible with future, more precise, lattice calculations.

The properties of the thermal Abelian color-magnetic monopoles in the maximally Abelian gauge are studied in the deconfinement phase of the lattice $SU(2)$ gluodynamics. To check universality of the monopole properties we employ the tadpole-improved Symanzik action. The simulated annealing algorithm combined with multiple gauge copies is applied for fixing the maximally Abelian gauge to avoid effects of Gribov copies. We compute the density, interaction parameters, thermal mass, and chemical potential of the thermal Abelian monopoles in the temperature range between $T_c$ and $3T_c$. In comparison with earlier findings our results for these quantities are improved either with respect to effects of Gribov copies or with respect to lattice artifacts.

We study the double charm decays of $B_c$ meson, by employing the perturbative QCD approach based on $k_T$ factorization. In this approach, we include the nonfactorizable emission diagrams and W annihilation diagrams, which are neglected in the previous naive factorization approach. The former are important in the color-suppressed modes, while the latter are important in most $B_c$ decay channels owing to the large Cabibbo-Kobayashi-Maskawa matrix elements. We make a comparison with those previous naive factorization results for the branching ratios and also give out the theoretical errors that were previously missed. We predict the transverse polarization fractions of $B_c\to D_{(s)}^{*+}{\overline{D}}^{*0}$, $D_{(s)}^{*+}{D}^{*0}$ decays for the first time. A large transverse polarization contribution that can reach 50%–60% is predicted in some of the $B_c$ meson decays.

We investigate the phase structure of the Nambu-Jona-Lasinio model at zero temperature, allowing for a two-dimensional spatial dependence of the chiral condensate. Applying the mean-field approximation, we consider various periodic structures with rectangular and hexagonal geometries, and minimize the corresponding free energy. We find that these two-dimensional chiral crystals are favored over homogeneous phases in a certain window in the region where the phase transition would take place when the analysis was restricted to homogeneous condensates. It turns out, however, that in this regime they are disfavored against a phase with a one-dimensional modulation of the chiral condensate. On the other hand, we find that square and hexagonal lattices eventually get favored at higher chemical potentials. Although stretching the limits of the model to some extent, this would support predictions from quarkyonic-matter studies.

We extend the Higgs triplet model so as to include dark matter candidates and a simple suppression mechanism for the vacuum expectation value ($v_{\Delta }$) of the triplet scalar field. The smallness of neutrino masses can be naturally explained with the suppressed value of $v_{\Delta }$ even when the triplet fields are at the TeV scale. The Higgs sector is extended by introducing $Z_2$-odd scalars (an $\mathrm{SU}(2{)}_L$ doublet $\eta$ and a real singlet $s_2^0$) in addition to a $Z_2$-even complex singlet scalar $s_1^0$ whose vacuum expectation value violates the lepton number conservation by a unit. In our model, $v_{\Delta }$ is generated by the one-loop diagram to which $Z_2$-odd particles contribute. The lightest $Z_2$-odd scalar boson can be a candidate for the dark matter. We briefly discuss a characteristic signal of our model at the LHC.

Using $586{\mathrm{pb}}^{-1}$ of $e^{+}{e}^{-}$ collision data acquired at $\sqrt{s}=4.170\mathrm{GeV}$ with the CLEO-c detector at the Cornell Electron Storage Ring, we report the first observation of $D_s^{*+}\to D_s^{+}{e}^{+}{e}^{-}$ with a significance of $5.3\sigma$. The ratio of branching fractions $\mathcal{B}(D_s^{*+}\to D_s^{+}{e}^{+}{e}^{-})/\mathcal{B}(D_s^{*+}\to D_s^{+}\gamma )$ is measured to be $[{0.72}_{-0.13}^{+0.15}(\mathrm{stat})\pm 0.10(\mathrm{syst})]\%$, which is consistent with theoretical expectations.

In this paper we give a simple proof that when the particle number is conserved, the Lagrangian of a barotropic perfect fluid is ${\mathcal{L}}_m=-\rho [c^2+\int P(\rho )/{\rho }^{2}d\rho ]$, where $\rho$ is the rest mass density and $P(\rho )$ is the pressure. To prove this result, neither additional fields nor Lagrange multipliers are needed. Besides, the result is applicable to a wide range of theories of gravitation. The only assumptions used in the derivation are: 1) the matter part of the Lagrangian does not depend on the derivatives of the metric, and 2) the particle number of the fluid is conserved (${\nabla }_{\sigma }(\rho u^{\sigma })=0$).

We derive boundary conditions for electromagnetic fields on a $\delta$-function plate. The optical properties of such a plate are shown to necessarily be anisotropic in that they only depend on the transverse properties of the plate. We unambiguously obtain the boundary conditions for a perfectly conducting $\delta$-function plate in the limit of infinite dielectric response. We show that a material does not “optically vanish” in the thin-plate limit. The thin-plate limit of a plasma slab of thickness $d$ with plasma frequency ${\omega }_p^2={\zeta }_p/d$ reduces to a $\delta$-function plate for frequencies ($\omega =i\zeta$) satisfying $\zeta d\ll \sqrt{{\zeta }_{p}d}\ll 1$. We show that the Casimir interaction energy between two parallel perfectly conducting $\delta$-function plates is the same as that for parallel perfectly conducting slabs. Similarly, we show that the interaction energy between an atom and a perfect electrically conducting $\delta$-function plate is the usual Casimir-Polder energy, which is verified by considering the thin-plate limit of dielectric slabs. The “thick” and “thin” boundary conditions considered by Bordag are found to be identical in the sense that they lead to the same electromagnetic fields.