We show that Chern-Simons (CS) modified gravity with a prescribed CS scalar field admits rotating black hole/string solutions with cylindrical topology of the horizon, and we present two intriguing physical examples of such configurations. First, we show that the Banados-Teitelboim-Zanelli stationary black string, which is obtained by adding a spacelike flat dimension to the Banados-Teitelboim-Zanelli black hole metric of three-dimensional gravity, solves the field equations of CS modified gravity with a specific source term irrespective of the choice of CS scalar field. Next, we consider the Lemos solution for a rotating, straight black string in general relativity and show that, for the CS scalar field being a function of the radial coordinate alone, this solution persists in CS modified gravity. We also present a new nontrivial (non-general relativity) Gödel-type solution to the vacuum field equations of CS modified gravity.

In this paper we explore different aspects of three dimensional Born-Infeld as well as Born-Infeld-Chern-Simons gravity. We show that the models have anti–de Sitter and anti–de Sitter wave vacuum solutions. Moreover, we observe that although Born-Infeld-Chern-Simons gravity admits a logarithmic solution, Born-Infeld gravity does not, though it has a limiting logarithmic solution as we approach the critical point.

Kinematically forbidden processes may be allowed in the presence of external gravitational fields. These can be taken into account by introducing generalized particle momenta. The corresponding transition probabilities can then be calculated to all orders in the metric deviation from the field-free expressions by simply replacing the particle momenta with their generalized counterparts. The procedure applies to particles of any spin and to any gravitational fields. Transition probabilities, emission power, and spectra are, to leading order, linear in the metric deviation. It is also shown how a small dissipation term in the particle wave equations can trigger a strong backreaction that introduces resonances in the radiative process and deeply affects the resulting gravitational background.

We investigate test particle trajectories in warped spacetimes with a thick brane warp factor, a cosmological on-brane line element, and a time dependent extra dimension. The geodesic equations are reduced to a first order autonomous dynamical system. Using analytical methods, we arrive at some useful general conclusions regarding possible trajectories. Oscillatory motion, suggesting confinement about the location of the thick brane, arises for a growing warp factor. On the other hand, we find runaway trajectories (exponential-like) for a decaying warp factor. Variations of the extra dimensional scale factor yield certain quantitative differences. Results obtained from explicit numerical evaluations match well with the qualitative conclusions obtained from the dynamical systems analysis.

We perform a comprehensive study of the emission of massive scalar fields by a higher-dimensional, simply rotating black hole both in the bulk and on the brane. We derive approximate, analytic results as well as exact numerical ones for the absorption probability, and demonstrate that the two sets agree very well in the low and intermediate-energy regime for scalar fields with mass $m_{\Phi }\le 1\mathrm{TeV}$ in the bulk and $m_{\Phi }\le 0.5\mathrm{TeV}$ on the brane. The numerical values of the absorption probability are then used to derive the Hawking radiation power emission spectra in terms of the number of extra dimensions, angular-momentum of the black hole and mass of the emitted field. We compute the total emissivities in the bulk and on the brane, and demonstrate that, although the brane channel remains the dominant one, the bulk-over-brane energy ratio is considerably increased (up to 34%) when the mass of the emitted field is taken into account.

Recent N-body simulations indicate that a thick disc of dark matter, corotating with the stellar disc, forms in a galactic halo after a merger at a redshift $z<2$. The existence of such a dark disc component in the Milky Way could affect dramatically dark matter signals in direct and indirect detection. In this letter, we discuss the possible signal enhancement in connection with the characteristics of the local velocity distributions. We argue that the enhancement is rather mild, but some subtle effects may arise. In particular, the annual modulation observed by DAMA becomes less constrained by other direct detection experiments.

In a recent paper, four of the present authors proposed a class of dark matter models where generalized parity symmetry leads to equality of dark matter abundance with baryon asymmetry of the Universe and predicts dark matter mass to be around 5 GeV. In this paper, we explore how this model can be tested in direct search experiments. In particular, we point out that if the dark matter happens to be the mirror neutron, the direct detection cross section has the unique feature that it increases at low recoil energy unlike the case of conventional weakly interacting massive particles. It is also interesting to note that the predicted spin-dependent scattering could make significant contribution to the total direct detection rate, especially for light nucleus. With this scenario, one could explain recent DAMA and CoGeNT results.

Once the existence of the Higgs boson is established at the CERN Large Hadron Collider (LHC), the focus will be shifted toward understanding its couplings to other particles. A crucial aspect is the measurement of the bottom Yukawa coupling, which is challenging at the LHC. In this paper we study the use of forward jet tagging as a means to secure the observation and to significantly improve the purity of the Higgs boson signal in the $H\to b\overline{b}$ decay mode from deep inelastic electron-proton scattering at the LHC. We demonstrate that the requirement of forward jet tagging in charged current events strongly enhances the signal-to-background ratio. The impact of a veto on additional partons is also discussed. Excellent response to hadronic shower and $b$-tagging capabilities are pivotal detector performance aspects.

We study the scalar sector of the general $N$-Higgs-doublet model via geometric constructions in the space of gauge orbits. We give a detailed description of the shape of the orbit space both for general $N$ and, in more detail, for $N=3$. We also comment on remarkable analogies between the $N$-Higgs-doublet model and quantum information theory.

The strong and electromagnetic decays of $X(4350)$ with quantum numbers $J^P=0^{++}$ and $2^{++}$ have been studied by using the effective Lagrangian approach. The coupling constant between $X(4350)$ and $D_s^{*}{D}_{s0}^{*}$ is determined with the help of the compositeness condition which means that $X(4350)$ is a bound state of $D_s^{*}{D}_{s0}^{*}$. Other coupling constants applied in the calculation are determined phenomenologically. Our numerical results show that, using the present data, the possibility that $X(4350)$ is a $D_s^{*}{D}_{s0}^{*}$ molecule cannot be ruled out within the present model.

Finite-density systems can be explored with lattice QCD through the calculation of multihadron correlation functions. Recently, systems with up to 12 ${\pi }^{+}$’s or $K^{+}$’s have been studied to determine the 3-${\pi }^{+}$ and 3-$K^{+}$ interactions, and the corresponding chemical potentials have been determined as a function of density. We derive recursion relations between correlation functions that allow this work to be extended to systems of arbitrary numbers of mesons and to systems containing many different types of mesons, such as ${\pi }^{+}$’s, $K^{+}$’s, ${\overline{D}}^0$’s, and $B^{+}$’s. These relations allow for the study of finite-density systems in arbitrary volumes and for the study of high-density systems.

Recent theoretical investigations have unveiled a rich structure in the quantum chromodynamics phase diagram, which consists of quark-gluon plasma and the hadronic phases but also supports the existence of a crossover transition ending at a critical end point (CEP). We find a too large variation in the determination of the coordinates of the CEP in the temperature ($T$) baryon chemical potential (${\mu }_B$) plane; and, therefore, its identification in the current heavy-ion experiments becomes debatable. Here we use an equation of state for a deconfined quark-gluon plasma using a thermodynamically-consistent quasiparticle model involving noninteracting quarks and gluons having thermal masses. We further use a thermodynamically-consistent excluded-volume model for the hadron gas, which was recently proposed by us. Using these equations of state, a first-order deconfining phase transition is constructed using Gibbs’s criteria. This leads to an interesting finding that the phase transition line ends at a critical end point (CEP) beyond which a crossover region exists. Using our thermal hadron gas model, we obtain a chemical freeze out curve, and we find that the CEP lies in close proximity to this curve as proposed by some authors. The coordinates of CEP are found to lie within the reach of Relativistic heavy-ion collider experiment.

In high-density QCD the hadron production stems from decay of mini jets that have the transverse momenta of the order of the saturation scale. It is shown in this paper that this idea is able to describe in a unique fashion both the inclusive hadron production for $\sqrt{s}\ge 546\mathrm{GeV}$ including the first data from LHC and the deep inelastic scattering at HERA. Recently reported data from ALICE, CMS, and ATLAS including inclusive charged-hadron transverse momentum and multiplicity distribution in $pp$ collisions are well described in our approach. We provide predictions for the upcoming LHC measurements.

We present the bulk thermodynamic properties and phase diagram of strongly interacting matter in an extension of the 3-flavor Nambu–Jona-Lasinio (NJL) and Polyakov–Nambu–Jona-Lasinio (PNJL) models of QCD. Using a three-momentum cutoff scheme, we have extended the multiquark interaction terms up to eight order so that the stability of the vacuum is ensured in these models. We explore the effects of various combinations of the two eight-quark couplings $g_1$ and $g_2$ and present a comparative study between the NJL and PNJL models as well as lattice QCD data. The main effect of the eight-quark interaction term is to shift the critical end point in the $T-\mu$ phase diagram to a lower value of $\mu$ and a higher value of $T$, thus bringing them closer to lattice QCD results.

The radiative seesaw model with an inert doublet has been shown to be attractive from a viewpoint of both neutrino masses and cold dark matter. However, if we apply this model to the explanation of the positron excess in the cosmic ray observed by PAMELA, a huge boost factor is required although it can be automatically explained that no antiproton excess has been observed there. We consider an extension of the model to enhance the thermally averaged annihilation cross section without changing the features of the model favored by both the neutrino oscillation and the relic abundance of dark matter. It is shown that the data of PAMELA and Fermi-LAT can be well explained in this extended model. Constraints from gamma ray observations are also discussed.

We use dispersion relations to evaluate the $\gamma Z$ box contribution to parity-violating electron scattering in the forward limit arising from the axial-vector coupling at the electron vertex. The calculation makes full use of the critical constraints from recent JLab data on electroproduction in the resonance region as well as high-energy data from HERA. At the kinematics of the $Q_{\mathrm{weak}}$ experiment, this gives a correction of ${0.0047}_{-0.0004}^{+0.0011}$ to the standard model value 0.0713(8) of the proton weak charge. While the magnitude of the correction is highly significant, the uncertainty is within the anticipated experimental uncertainty of $\pm 0.003$.

It is recently claimed by Nekrasov and Shatashvili that the $\mathcal{N}=2$ gauge theories in the $\Omega$ background with ${ϵ}_1=\hslash$, ${ϵ}_2=0$ are related to the quantization of certain algebraic integrable systems. We study the special case of SU(2) pure gauge theory; the corresponding integrable model is the ${\mathrm{A}}_1$ Toda model, which reduces to the sine-Gordon quantum mechanics problem. The quantum effects can be expressed as the WKB series written analytically in terms of hypergeometric functions. We obtain the magnetic and dyonic expansions of the Nekrasov theory by studying the property of hypergeometric functions in the magnetic and dyonic regions on the moduli space. We also discuss the relation between the electric-magnetic duality of gauge theory and the action-action duality of the integrable system.

Results are presented from numerical simulations of the flat-space nonlinear Klein-Gordon equation with an asymmetric double-well potential in spherical symmetry. Exit criteria are defined for the simulations that are used to help understand the boundaries of the basins of attraction for Gaussian “bubble” initial data. The first exit criterion, based on the immediate collapse or expansion of bubble radius, is used to observe the departure of the scalar field from a static intermediate attractor solution. The boundary separating these two behaviors in parameter space is smooth and demonstrates a time-scaling law with an exponent that depends on the asymmetry of the potential. The second exit criterion differentiates between the creation of an expanding true-vacuum bubble and dispersion of the field leaving the false vacuum; the boundary separating these basins of attraction is shown to demonstrate fractal behavior. The basins are defined by the number of bounces that the field undergoes before inducing a phase transition. A third, hybrid exit criterion is used to determine the location of the boundary to arbitrary precision and to characterize the threshold behavior. The possible effects this behavior might have on cosmological phase transitions are briefly discussed.

The cosmic microwave background anisotropies provide a unique opportunity to constrain simultaneous variations of the fine-structure constant $\alpha$ and Newton’s gravitational constant $G$. Those correlated variations are possible in a wide class of theoretical models. In this brief paper we show that the current data, assuming that particle masses are constant, give no clear indication for such variations, but already prefer that any relative variations in $\alpha$ should be of the same sign of those of $G$ for variations of $\sim 1\%$. We also show that a cosmic complementarity is present with big bang nucleosynthesis and that a combination of current CMB and big bang nucleosynthesis data strongly constraints simultaneous variations in $\alpha$ and $G$. We finally discuss the future bounds achievable by the Planck satellite mission.

A precise determination of the local dark matter density and an accurate control over the corresponding uncertainties are of paramount importance for dark matter (DM) searches. Using very recent high-resolution numerical simulations of a Milky Way like object, we study the systematic uncertainties that affect the determination of the local dark matter density based on dynamical measurements in the Galaxy. In particular, extracting from the simulation with baryons the orientation of the Galactic stellar disk with respect to the DM distribution, we study the DM density for an observer located at $\sim 8\mathrm{kpc}$ from the Galactic center on the stellar disk, ${\rho }_0$. This quantity is found to be always larger than the average density in a spherical shell of the same radius ${\overline{\rho }}_0$, which is the quantity inferred from dynamical measurements in the Galaxy, and to vary in the range ${\rho }_0/{\overline{\rho }}_0=1.01–1.41$. This suggests that the actual dark matter density in the solar neighborhood is on average 21% larger than the value inferred from most dynamical measurements, and that the associated systematic errors are larger than the statistical errors recently discussed in the literature.