Axisymmetric numerical simulations of rotating stellar core collapse to a neutron star are performed in the framework of full general relativity. The so-called Cartoon method, in which the Einstein field equations are solved in Cartesian coordinates and the axisymmetric condition is imposed around the $y=0\mathrm{}$ plane, is adopted. The hydrodynamic equations are solved in cylindrical coordinates (on the $y=0\mathrm{}$ plane in Cartesian coordinates) using a high-resolution shock-capturing scheme with maximum grid size $\mathrm{}(2500,2500).$ A parametric equation of state is adopted to model collapsing stellar cores and neutron stars following Dimmelmeier, Font, and Müller. It is found that the evolution of the central density during the collapse, bounce, and formation of protoneutron stars agrees well with that in the work of Dimmelmeier, Font, and Müller in which an approximate general relativistic formulation is adopted. This indicates that such an approximation is appropriate for following axisymmetric stellar core collapses and the subsequent formation of protoneutron stars. Gravitational waves are computed using a quadrupole formula. It is found that the waveforms are qualitatively in good agreement with those by Dimmelmeier, Font, and Müller. However, quantitatively, two waveforms do not agree well. The possible reasons for the disagreement are discussed.

We cross-correlate the cosmic microwave background temperature anisotropies observed by the Wilkinson Microwave Anisotropy Probe (WMAP) with the projected distribution of extended sources in the Two Micron All Sky Survey (2MASS). By modeling the theoretical expectation for this signal, we extract the signatures of dark energy [integrated Sachs-Wolfe effect (ISW)], hot gas [thermal Sunyaev-Zeldovich (SZ) effect], and microwave point sources in the cross-correlation. Our strongest signal is the thermal SZ, at the $3.1–3.7\sigma$ level, which is consistent with the theoretical prediction based on observations of x-ray clusters. We also see the ISW signal at the $2.5\sigma$ level, which is consistent with the expected value for the concordance $\Lambda \mathrm{CDM}$ cosmology, and is an independent signature of the presence of dark energy in the Universe. Finally, we see the signature of microwave point sources at the $2.7\sigma$ level.

The hybrid model with a scalar “inflaton” field coupled to a “Higgs” field with a broken symmetry potential is one of the promising models for inflation and (p)reheating after inflation. We consider the nonequilibrium evolution of the quantum fields of this model with quantum back reaction in the Hartree approximation, in particular the transition of the Higgs field from the metastable “false vacuum” to the broken symmetry phase. We have performed the renormalization of the equations of motion, of the gap equations, and of the energy density, using dimensional regularization. We study the influence of the back reaction on the evolution of the classical fields and of the quantum fluctuations. We observe that back reaction plays an important role over a wide range of parameters. Some implications of our investigation for the preheating stage after cosmic inflation are presented.

We formalize the Hubble slow-roll formalism for inflationary dynamics in Randall-Sundrum type II braneworld cosmologies, defining Hubble slow-roll parameters which can be used along with the Hamilton-Jacobi formalism. Focusing on the high-energy limit, we use these to calculate the exact power spectrum for power-law inflation, and then perturb around this solution to derive the higher-order expression for the density perturbations (sometimes called the Stewart-Lyth correction) of slow-roll braneworld models. Finally we apply our result to specific examples of potentials to calculate the correction to the amplitude of the power spectrum, and compare it with the standard cosmology. We find that the amplitude is not changed significantly by the higher-order correction.

Although well motivated from theoretical arguments, the cosmological constant barrier, i.e., the imposition that the equation-of-state parameter of dark energy $({\omega }_x\equiv p_x/{\rho }_x)$ is $>~-1,$ seems to introduce bias in the parameter determination from statistical analyses of observational data. In this regard, phantom dark energy or superquintessence has been proposed in which the usual imposition $\omega >~-1$ is relaxed. Here, we study possible observational limits to the phantom behavior of the dark energy from recent distance estimates of galaxy clusters obtained from interferometric measurements of the Sunyaev-Zel’dovich effect and x-ray observations, type Ia supernova data, and cosmic microwave background measurements. We find that there is much acceptable parameter space beyond the $\Lambda$ barrier, which opens, from a purely observational point of view, the possibility of the existence of more exotic forms of energy in the Universe.

A toy model is defined and solved perturbatively with the aim of examining some claimed “resonant” enhancements of certain reaction rates that enter popular models of leptogenesis. We find (a) that such enhancements are absent, and (b) that the perturbative solution, as done correctly using finite-temperature field theory, is well defined without the “resumming” procedures found in the literature. The pathologies that led to the perceived need for these procedures are an artifact of uncritical use of weighted vacuum cross sections in the determination of rates, without adequate attention to the effects of the medium upon the single particle states within it.

The perturbative three-loop result for the thermodynamic potential of QCD at finite temperature and chemical potential as obtained in the framework of dimensional reduction is compared with the exact result in the limit of large flavor number. The apparent convergence of the former as well as possibilities for optimization are investigated. The corresponding optimized results for full QCD are given for the case of two massless quark flavors.

We propose a new method of computing real emission contributions to hard QCD processes. Our approach uses sector decomposition of the exclusive final-state phase space to enable extraction of all singularities of the real emission matrix elements before integration over any kinematic variable. The exact kinematics of the real emission process are preserved in all regions of phase space. Traditional approaches to extracting singularities from real emission matrix elements, such as phase space slicing and dipole subtraction, require both the determination of counterterms for double real emission amplitudes in singular kinematic limits and the integration of these contributions analytically to cancel the resulting singularities against virtual corrections. Our method addresses both of these issues. The implementation of constraints on the final-state phase space, including various jet algorithms, is simple using our approach. We illustrate our method using $e^{+}{e}^{-}\to$ jets at $O\left({\alpha }_S^2\right)$ as an example.

In the Randall-Sundrum model, radion-Higgs mixing is weakly suppressed by the effective electroweak scale. One of its novel features is a sizable three-point vertex among the Kaluza-Klein (KK) graviton, Higgs boson, and radion. We explore the potential of the Fermilab Tevatron and the CERN LHC in probing radion-Higgs mixing via the associated production of the radion with the Higgs boson. The observation of the rare decay of the KK gravitons into the radion and Higgs boson is then the direct and exclusive signal of radion-Higgs mixing. We also study all the partial decay widths of the KK gravitons in the presence of radion-Higgs mixing and find that if the mixing parameter is of the order of 1, the decay rate into a radion and a Higgs boson becomes as large as that into a Higgs boson pair, with the branching ratio of the order of ${10}^{-3}.$

We compute the rates for pp annihilation into chargino pairs via the Drell-Yan process taking into account the effects of supersymmetric soft phases, at a proton-proton collider. In particular, the phase of the μ parameter gains direct accessibility via the production of dissimilar charginos. The phases of the trilinear soft masses do not have a significant effect on the cross sections.

The infrared features of Landau gauge QCD are studied by lattice simulation of $\beta {=6.0,16\mathrm{}}^4{,24\mathrm{}}^4{,32\mathrm{}}^4$ and $\beta {=6.4,32\mathrm{}}^4{,48\mathrm{}}^4.$ We adopt two definitions of the gauge field, (1) U linear and (2) $\log U,$ and measured the gluon propagator and ghost propagator. The infrared singularity of the gluon propagator is less than that of the tree level result, but the gluon propagator at 0 momentum remains finite. The infrared singularity of the ghost propagator is stronger than the tree level. The QCD running coupling measured by using the gluon propagator and the ghost propagator has a maximum ${\alpha }_s\mathrm{}\left(p\right)\mathrm{}\simeq 1$ at around $p=0.5\mathrm{}$ GeV and decreases as p approaches 0. The data are analyzed with use of the formula of the principle of minimal sensitivity and the effective charge method, and by the contour-improved perturbation method, which suggest the necessity of the resummation of the perturbation series in the infrared region together with the existence of the infrared fixed point. The Kugo-Ojima parameter is about $-0.8$ in contrast with the theoretically expected value of $-1.$ The color off-diagonal part of the ghost propagator in the Landau gauge is consistent with zero, and its fluctuation can be parametrized as a $\mathrm{constant}{/\left(\mathrm{qa}\right)\mathrm{}}^4.$

The status of exotic baryons is analyzed in the limit of a large number of colors $N_c.$ Several toy models reproducing the main features of the large-$N_c$ QCD are studied in order to clarify the recent controversy concerning the consistency of various approaches to the ${1/N}_c$ expansion for exotic baryons. The analysis reveals a number of contradictions between the systematic ${1/N}_c$ expansion and the rigid-rotator approximation, including the problems of this approximation in the description of exotic baryons.

The domain model for the QCD vacuum has previously been developed and shown to exhibit confinement of quarks, a strong correlation of the local chirality of quark modes, and a duality of the background domainlike gluon field. Quark fluctuations satisfy a chirality violating boundary condition parametrized by a random chiral angle ${\alpha }_j$ on the jth domain. The free energy of an ensemble of $\overrightarrow{N}\infty$ domains depends on $\{{\alpha }_j,j=1,\dots ,N\}$ through the logarithm of the quark determinant. Its parity odd part is given by the axial anomaly. The anomaly contribution to the free energy suppresses continuous axial $U\left(1\right)\mathrm{}$ degeneracy in the ground state, leaving only a residual axial $Z\left(2\right)\mathrm{}$ symmetry. This discrete symmetry and the flavor ${SU(N}_f{)}_L\times {SU(N}_f{)}_R$ chiral symmetry in turn are spontaneously broken with a quark condensate arising due to the asymmetry of the spectrum of the Dirac operator. In order to illustrate the splitting between the ${\eta }^{\prime }$ from octet pseudoscalar mesons realized in the domain model, we estimate the masses of the light pseudoscalar and vector mesons.

We perform a next to leading order QCD global analysis of nuclear deep inelastic scattering and Drell-Yan data using the convolution approach to parametrize nuclear parton densities. We find both a significant improvement in the agreement with data compared to previous extractions, and substantial differences in the scale dependence of nuclear effects compared to leading order analyses.

The supersymmetric standard model with right-handed neutrino supermultiplets generically contains a soft supersymmetry breaking mass term: $\delta {L=B}_{\nu }M{\tilde{\nu }}_R{\tilde{\nu }}_R/2.\mathrm{}$ We call this operator the “neutrino B term.” We show that the neutrino B term can give the dominant effects from the neutrino sector to lepton-flavor-violating processes and to lepton electric dipole moments.

We report on new results in Witten’s cubic string field theory for the off-shell factor in the 4-tachyon amplitude that was not fully obtained explicitly before. This is achieved by completing the derivation of the Veneziano formula in the Moyal star formulation of Witten’s string field theory (MSFT). We also demonstrate a detailed agreement of MSFT with a number of on-shell and off-shell computations in other approaches to Witten’s string field theory. We extend the techniques of computation in MSFT, and show that the $j=0\mathrm{}$ representation of $\mathrm{SL}\mathrm{}(2,R)\mathrm{}$ generated by the Virasoro operators $L_0{,L}_{\pm 1}$ is a key structure in practical computations for generating numbers. We provide more insight into the Moyal structure that simplifies string field theory, and develop techniques that could be applied more generally, including nonperturbative processes.

We perform a one-loop test of the holographic interpretation of the Karch-Randall model, whereby a massive graviton appears on an ${\mathrm{AdS}}_4$ brane in an ${\mathrm{AdS}}_5$ bulk. Within the AdS/CFT framework, we examine the quantum corrections to the graviton propagator on the brane, and demonstrate that they induce a graviton mass in exact agreement with the Karch-Randall result. Interestingly enough, at one loop order, the spin-0, spin-1/2, and spin-1 loops contribute to the dynamically generated $(\mathrm{mass}{)}^2$ in the same $1:3:12$ ratio as enter the Weyl anomaly and the ${1/r}^3$ corrections to the Newtonian gravitational potential.

With nonequilibrium applications in mind we present in this paper (the first in a series of three) a self-contained calculation of the hydrostatic pressure of the $O\left(N\right)\mathrm{}\lambda {\phi }^4$ theory at finite temperature. By combining the Keldysh-Schwinger closed-time path formalism with thermal Dyson-Schwinger equations we compute in the large N limit the hydrostatic pressure in a fully resumed form. We also calculate the high-temperature expansion for the pressure (in $D=4)$ using the Mellin transform technique. The result obtained extends the results found by Drummond et al. [Nucl. Phys. B524, 579 (1998)] and Amelino-Camelia and Pi [Phys. Rev. D 47, 2356 (1993)]. The latter are reproduced in the limits $m_r\mathrm{}\left(0\right)\mathrm{}\to 0,$ $\overrightarrow{T}\infty ,$ and $\overrightarrow{T}\infty ,$ respectively. Important issues of renormalizibility of composite operators at finite temperature are addressed and the improved energy-momentum tensor is constructed. The utility of the hydrostatic pressure in the nonequilibrium quantum systems is discussed.

We analyze the asymptotic structure of general gravitational and electromagnetic fields near an anti–de Sitter–like conformal infinity. The dependence of the radiative component of the fields on a null direction along which the infinity is approached is obtained. The directional pattern of outgoing and ingoing radiation, which supplements standard peeling property, is determined by the algebraic (Petrov) type of the fields and also by the orientation of the principal null directions with respect to timelike infinity. The dependence on the orientation is a new feature if compared to spacelike infinity.