Photon distribution amplitudes up to twist four are calculated within the nonlocal chiral quark model with a simple pole ansatz for momentum dependence of the constituent quark mass. Calculations are performed using a modified electromagnetic vector current in order to satisfy Ward identities. Quark condensate and magnetic susceptibility of the QCD vacuum entering definitions of the distribution amplitudes are computed and compared with existing phenomenological estimates. Both real and off-shell photons are considered and relevant form factors are calculated. Our results are analytical up to the numerical solution of certain algebraic equations.

In analogy with the recently proposed lepton mixing sum rules, we derive quark mixing sum rules for the case of hierarchical quark mass matrices with 1-3 texture zeros, in which the separate up and down-type 1-3 mixing angles are approximately zero, and $V_{ub}$ is generated from $V_{cb}$ as a result of 1-2 up-type quark mixing. Using the sum rules, we discuss the phenomenological viability of such textures, including up to four texture zeros, and show how the right-angled unitarity triangle, i.e., $\alpha \approx 90°$, can be accounted for by a remarkably simple scheme involving real mass matrices apart from a single element being purely imaginary. In the framework of grand unified theories, we show how the quark and lepton mixing sum rules may combine to yield an accurate prediction for the reactor angle.

We present measurements of the top quark mass using $m_{\mathrm{T}2}$, a variable related to the transverse mass in events with two missing particles. We use the template method applied to $t\overline{t}$ dilepton events produced in $p\overline{p}$ collisions at Fermilab’s Tevatron Collider and collected by the CDF detector. From a data sample corresponding to an integrated luminosity of $3.4{\mathrm{fb}}^{-1}$, we select 236 $t\overline{t}$ candidate events. Using the $m_{\mathrm{T}2}$ distribution, we measure the top quark mass to be ${\mathrm{M}}_{\mathrm{top}}={168.0}_{-4.0}^{+4.8}(\mathrm{stat})\pm 2.9(\mathrm{syst})\mathrm{GeV}/c^2$. By combining $m_{\mathrm{T}2}$ with the reconstructed top quark mass distributions based on a neutrino weighting method, we measure ${\mathrm{M}}_{\mathrm{top}}=169.3\pm 2.7(\mathrm{stat})\pm 3.2(\mathrm{syst})\mathrm{GeV}/c^2$. This is the first application of the $m_{\mathrm{T}2}$ variable in a mass measurement at a hadron collider.

We show that in four-dimensional gauge theories dual to five-dimensional Einstein gravity coupled to a single scalar field in the bulk, the derivative of the single heavy quark free energy in the deconfined phase is $d{F}_Q(T)/dT\sim -1/c_s^2(T)$, where $c_s(T)$ is the speed of sound. This general result provides a direct link between the softest point in the equation of state of strongly-coupled plasmas and the deconfinement phase transition described by the expectation value of the Polyakov loop. We give an explicit example of a gravity dual with black hole solutions that can reproduce the lattice results for the expectation value of the Polyakov loop and the thermodynamics of $SU(3)$ Yang-Mills theory in the (nonperturbative) temperature range between $T_c$ and $3T_c$.

We examine the separability of the Nambu-Goto equation for test strings in a shape of toroidal spiral in a five-dimensional Kerr-AdS black hole. In particular, for a “Hopf loop” string which is a special class of the toroidal spiral strings, we show the complete separation of variables occurs in two cases, Kerr background and Kerr-AdS background with equal angular momenta. We also obtain the dynamical solution for the Hopf loop around a black hole and for the general toroidal spiral in Minkowski background.

We investigate static non-Abelian black hole solutions of anti–de Sitter (AdS) Einstein-Yang-Mills-dilaton gravity, which is obtained as a consistent truncation of five-dimensional maximal gauged supergravity. If the dilaton is (consistently) set to zero, the remaining equations of motion, with a spherically-symmetric ansatz, may be derived from a superpotential. The associated first-order equations admit an explicit solution supported by a non-Abelian $SU(2)$ gauge potential, which has a logarithmically growing mass term. In an extremal limit the horizon geometry becomes ${\mathrm{AdS}}_2\times S^3$. If the dilaton is also excited, the equations of motion cannot easily be solved explicitly, but we obtain the asymptotic form of the more general non-Abelian black holes in this case. An alternative consistent truncation, in which the Yang-Mills fields are set to zero, also admits a description in terms of a superpotential. This allows us to construct explicit wormhole solutions (neutral spherically-symmetric domain walls). These solutions may be generalized to dimensions other than five.

Analytical solutions of Maxwell equations in background spacetime of a black hole in a braneworld immersed in an external uniform magnetic field have been found. The influence of both magnetic and brane parameters on the effective potential of the radial motion of a charged test particle around a slowly rotating black hole in a braneworld immersed in a uniform magnetic field has been investigated by using the Hamilton-Jacobi method. An exact analytical solution for dependence of the radius of the innermost stable circular orbits (ISCO) $r_{\mathrm{ISCO}}$ from the brane parameter for the motion of a test particle around a nonrotating isolated black hole in a braneworld has been derived. It has been shown that the radius $r_{\mathrm{ISCO}}$ is monotonically growing with the increase of the module of the brane tidal charge. A comparison of the predictions on $r_{\mathrm{ISCO}}$ of the braneworld model and of the observational results of ISCO from relativistic accretion disks around black holes provided the upper limit for the brane tidal charge $\lesssim {10}^9{\mathrm{cm}}^2$.

We show that in modified $f(R)$ type gravity models with nonminimal coupling between matter and geometry, both the matter Lagrangian and the energy-momentum tensor are completely and uniquely determined by the form of the coupling. This result is obtained by using the variational formulation for the derivation of the equations of motion in the modified gravity models with geometry-matter coupling, and the Newtonian limit for a fluid obeying a barotropic equation of state. The corresponding energy-momentum tensor of the matter in modified gravity models with nonminimal coupling is more general than the usual general-relativistic energy-momentum tensor for perfect fluids, and it contains a supplementary, equation of state dependent term, which could be related to the elastic stresses in the body, or to other forms of internal energy. Therefore, the extra force induced by the coupling between matter and geometry never vanishes as a consequence of the thermodynamic properties of the system, or for a specific choice of the matter Lagrangian, and it is nonzero in the case of a fluid of dust particles.

The complete analytical solutions of the geodesic equations in Kerr-de Sitter and Kerr-anti-de Sitter space-times are presented. They are expressed in terms of Weierstrass elliptic $\wp$, $\zeta$, and $\sigma$ functions as well as hyperelliptic Kleinian $\sigma$ functions restricted to the one-dimensional $\theta$ divisor. We analyze the dependency of timelike geodesics on the parameters of the space-time metric and the test-particle and compare the results with the situation in Kerr space-time with vanishing cosmological constant. Furthermore, we systematically can find all last stable spherical and circular orbits and derive the expressions of the deflection angle of flyby orbits, the orbital frequencies of bound orbits, the periastron shift, and the Lense-Thirring effect.

We investigate models of interacting dark matter and dark energy for the Universe in a spatially flat Friedmann-Robertson-Walker space-time. We find the “source equation” for the total energy density and determine the energy density of each dark component. We introduce an effective one-fluid description to evidence that interacting and unified models are related to each other, analyze the effective model, and obtain the attractor solutions. We study linear and nonlinear interactions, the former comprises a linear combination of the dark matter and dark energy densities, their first derivatives, the total energy density, its first and second derivatives, and a function of the scale factor. The latter is a possible generalization of the linear interaction consisting of an aggregate of the above linear combination and a significant nonlinear term built with a rational function of the dark matter and dark energy densities homogeneous of degree 1. We solve the evolution equations of the dark components for both interactions and examine exhaustively several examples. There exist cases where the effective one-fluid description produces different alternatives to the $\Lambda \mathrm{CDM}$ model and cases where the problem of coincidence is alleviated. In addition, we find that some nonlinear interactions yield an effective one-fluid model with a Chaplygin gas equation of state, whereas others generate cosmological models with de Sitter and power-law expansions. We show that a generic nonlinear interaction induces an effective equation of state which depends on the scale factor in the same way as the variable modified Chaplygin gas model, giving rise to the “relaxed Chaplygin gas model.”

In this paper the tachyonic resonance preheating generated from the bosonic trilinear $\varphi {\chi }^2$ interactions in an expanding universe is studied. In $\lambda {\varphi }^4/4$ inflationary model the trilinear interaction, in contrast to the four-legs ${\varphi }^2{\chi }^2$, breaks the conformal symmetry explicitly and the resonant source term becomes nonperiodic, making the Floquet theorem inapplicable. We find that the occupation number of the produced $\chi$ particles has a nonlinear exponential growth with exponent $\sim x^{3/2}$, where $x$ is the conformal time. This should be contrasted with preheating from a periodic resonant source arising, for example, from the four-legs ${\varphi }^2{\chi }^2$ interaction, where the occupation number has a linear exponential growth. We present an analytic method to compute the interference term coming from phases accumulated in nontachyonic scattering regions and show that the effects of the interference term cause ripples on $x^{3/2}$ curve, a result which is confirmed by numerical analysis. Studying the effects of backreaction of the $\chi$ particles, we show that tachyonic resonance preheating in our model can last long enough to transfer most of the energy from the background inflation field $\varphi$, providing an efficient model for preheating in the chaotic inflation models.

We reconsider the proposal of excited dark matter (DM) as an explanation for excess 511 keV gamma rays from positrons in the Galactic center. We quantitatively compute the cross section for DM annihilation to nearby excited states, mediated by exchange of a new light gauge boson with off-diagonal couplings to the DM states. In models where both excited states must be heavy enough to decay into $e^{+}{e}^{-}$ and the ground state, the predicted rate of positron production is never large enough to agree with observations, unless one makes extreme assumptions about the local circular velocity in the Milky Way, or alternatively if there exists a metastable population of DM states which can be excited through a mass gap of less than 650 keV, before decaying into electrons and positrons.

A new class of four-dimensional, hairy, stationary solutions of the Einstein-Maxwell-$\Lambda$ system with a conformally coupled scalar field is obtained. The metric belongs to the Plebański-Demiański family and hence its static limit has the form of the charged (A)dS $C$ metric. It is shown that, in the static case, a new family of hairy black holes arises. They turn out to be cohomogeneity-two, with horizons that are neither Einstein nor homogenous manifolds. The conical singularities in the $C$ metric can be removed due to the backreaction of the scalar field providing a new kind of regular, radiative spacetime. The scalar field carries a continuous parameter proportional to the usual acceleration present in the $C$ metric. In the zero-acceleration limit, the static solution reduces to the dyonic Bocharova-Bronnikov-Melnikov-Bekenstein solution or the dyonic extension of the Martínez-Troncoso-Zanelli black holes, depending on the value of the cosmological constant.

We present the calculations of the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the Kaluza-Klein (KK) graviton and photon associated production process $pp\to \gamma G_{\mathrm{KK}}+X$ in the large extra dimensions model at the LHC. We show that the NLO QCD corrections in general enhance the total cross sections and reduce the dependence of the total cross sections on the factorization and renormalization scales. When jet veto is considered, the NLO corrections reduce the total cross sections. We also calculate some important differential cross sections for this process at NLO: the missing transverse momentum distribution, the transverse momentum distribution, and the pseudorapidity distribution of photon.

The sneutrino is a viable candidate for the next-to-lightest supersymmetric particle (NLSP) in supersymmetry spectra with gravitino LSP. In this work we study the collider implications of this possibility. In particular, we investigate whether the LHC can distinguish it (at least, in some cases) from alternative spectra, such as those with a neutralino LSP. We show that there exists a complete family of experimentally allowed and theoretically motivated spectra with sneutrino NLSP, which exhibit very distinctive multilepton signals that are difficult to fake within the next-to-minimal supersymmetric standard model. We study these signals in detail, including the techniques necessary to find them. We demonstrate our analysis approach on simulations incorporating backgrounds.

We study the potential of the international linear collider (ILC) at $\sqrt{s}=500\mathrm{GeV}$ to probe new dark matter motivated scenario where the bottom squark (sbottom) is the next-to-lightest supersymmetric particle. For this scenario, which is virtually impossible for the LHC to test, the ILC has a potential to cover a large fraction of the parameter space. The challenge is due to a very low energy of jets, below 20–30 GeV, which pushes the jet clustering and flavor tagging algorithms to their limits. The process of sbottom pair production was studied within the SiD detector concept. We demonstrate that ILC offers a unique opportunity to test the supersymmetry parameter space motivated by the sbottom-neutralino coannihilation scenario in cases when the sbottom production is kinematically accessible. The study was done with the full SiD simulation and reconstruction chain including all standard model and beam backgrounds.

We report on calculations of the charmonium and bottomonium spectrum in lattice QCD. We use ensembles of gauge fields with three flavors of sea quarks, simulated with the asqtad improved action for staggered fermions. For the heavy quarks we employ the Fermilab interpretation of the clover action for Wilson fermions. These calculations provide a test of lattice QCD, including the theory of discretization errors for heavy quarks. We provide, therefore, a careful discussion of the results in light of the heavy-quark effective Lagrangian. By and large, we find that the computed results are in agreement with experiment, once parametric and discretization errors are taken into account.

It is well known that neutrinoless double decay is going to play a crucial role in settling the neutrino properties, which cannot be extracted from the neutrino oscillation data. It is, in particular, expected to settle the absolute scale of neutrino mass and determine whether the neutrinos are Majorana particles, i.e. they coincide with their own antiparticles. In order to extract the average neutrino mass from the data, one must be able to estimate the contribution of all possible high mass intermediate particles. The latter, which occur in practically all extensions of the standard model, can, in principle, be differentiated from the usual mass term, if data from various targets are available. One, however, must first be able to reliably calculate the corresponding nuclear matrix elements. Such calculations are extremely difficult since the effective transition operators are very short ranged. For such operators processes like pionic contributions, which are usually negligible, turn out to be dominant. We study such an effect in a nonrelativistic quark model for the pion and the nucleon.

We argue that already the first year LHC run at $\sqrt{s}=7\mathrm{TeV}$ will provide a quick and effective way to test the dynamics of the color dipole-gluon interactions and the small $x$ behavior of the gluon density in the proton by studying vector meson photoproduction in ultraperipheral proton-proton collisions.

We derive the equations of motion of an extended test body in the context of Einstein’s theory of gravitation. The equations of motion are obtained via a multipolar approximation method and are given up to the quadrupolar order. Special emphasis is put on the explicit construction of the so-called canonical form of the energy-momentum density. The set of gravitational multipolar moments and the corresponding equations of motion allow for a systematic comparison to competing multipolar approximation schemes.