Polarized deep-inelastic scattering data on longitudinally polarized hydrogen and deuterium targets have been used to determine double-spin asymmetries of cross sections. Inclusive and semi-inclusive asymmetries for the production of positive and negative pions from hydrogen were obtained in a reanalysis of previously published data. Inclusive and semi-inclusive asymmetries for the production of negative and positive pions and kaons were measured on a polarized deuterium target. The separate helicity densities for the up and down quarks and the anti-up, anti-down, and strange sea quarks were computed from these asymmetries in a “leading order” QCD analysis. The polarization of the up-quark is positive and that of the down-quark is negative. All extracted sea quark polarizations are consistent with zero, and the light quark sea helicity densities are flavor symmetric within the experimental uncertainties. First and second moments of the extracted quark helicity densities in the measured range are consistent with fits of inclusive data.

We report on measurements of event-by-event charge fluctuations in ${\pi }^{+}\mathrm{p}$ and ${\mathrm{K}}^{+}\mathrm{p}$ collisions at $250\mathrm{G}\mathrm{e}\mathrm{V}/c$. The dependence of these fluctuations on the size of the rapidity windows are presented for the first time in the full phase-space domain. The corrections for the influence of global charge conservation and leading-particle stopping are tested by the data. The discrepancy due to incomplete correction given by STAR and PHENIX are estimated. The dependence of the fluctuations on the position of the rapidity bin and on the multiplicity at different rapidity windows are also presented.

We construct the first $D=4$ Minkowski string theory vacua of flux compactification which are (i) chiral, (ii) free of NSNS and RR tadpoles, and (iii) $\mathcal{N}=1$ or $\mathcal{N}=0$ supersymmetric. In the latter case SUSY is softly broken by the fluxes, with soft terms being generated in the gauge and chiral sectors of the theory. In addition, the low energy spectrum of the theory is MSSM-like with three generations of chiral matter, the dilaton/complex structure moduli are stabilized and the supergravity background involves a warped metric.

We explore a new mechanism for detection of neutrino-induced showers via surface waves at radio frequencies. Air-dielectric surface waves exist on a plane boundaries that have attenuation lengths 2.82 that of the dielectric, and their amplitudes fall only by the inverse square root of propagation distance. Allowing for substantial coupling uncertainties, surface waves may provide a useful mechanism for neutrino detection in polar ice, promoting the development of neutrino telescopes in the energy regime above ${10}^{15}$ eV.

Regarding long-life particle produced during preheating after inflation as dark matter, we find that its backreaction on the field $\phi$ can lock $\phi$ in a false vacuum up to today under certain conditions. This false vacuum can drive the accelerated expansion of universe at late time and play the role of dark energy. When the number density of dark matter particle is diluted to some value, the field $\phi$ will become tachyonic and roll to its true minimum rapidly, and the acceleration of universe ceases. We discuss the constraints on the parameters of model from the observations.

The Lee model was introduced in the 1950s as an elementary quantum field theory in which mass, wave function, and charge renormalization could be carried out exactly. In early studies of this model it was found that there is a critical value of $g^2$, the square of the renormalized coupling constant, above which $g_0^2$, the square of the unrenormalized coupling constant, is negative. Thus, for $g^2$ larger than this critical value, the Hamiltonian of the Lee model becomes non-Hermitian. It was also discovered that in this non-Hermitian regime a new state appears whose norm is negative. This state is called a ghost state. It has always been assumed that in this ghost regime the Lee model is an unacceptable quantum theory because unitarity appears to be violated. However, in this regime while the Hamiltonian is not Hermitian, it does possess $\mathcal{P}\mathcal{T}$ symmetry. It has recently been discovered that a non-Hermitian Hamiltonian having $\mathcal{P}\mathcal{T}$ symmetry may define a quantum theory that is unitary. The proof of unitarity requires the construction of a new time-independent operator called $\mathcal{C}$. In terms of $\mathcal{C}$ one can define a new inner product with respect to which the norms of the states in the Hilbert space are positive. Furthermore, it has been shown that time evolution in such a theory is unitary. In this paper the $\mathcal{C}$ operator for the Lee model in the ghost regime is constructed in the $V/N\theta$ sector. It is then shown that the ghost state has a positive norm and that the Lee model is an acceptable unitary quantum field theory for all values of $g^2$.

We present new supersymmetric solutions of five-dimensional minimal supergravity that describe concentric black rings with an optional black hole at the common center. Configurations of two black rings are found which have the same conserved charges as a single rotating black hole; these black rings can have a total horizon area less than, equal to, or greater than the black hole with the same charges. A numerical investigation of these particular black-ring solutions suggests that they do not have closed timelike curves.

Codimension two branes play an interesting role in attacking the cosmological constant problem. Recently, in order to handle some problems in codimension two branes in Einstein gravity, Bostock et al. proposed using six-dimensional Einstein-Gauss-Bonnet (EGB) gravity instead of six-dimensional Einstein gravity. In this paper, we present the solutions of codimension two branes in six-dimensional EGB gravity. We show that Einstein's equations take a factorizable form for a factorized metric tensor ansatz even in the presence of the higher-derivative Gauss-Bonnet term. Especially, a new feature of the solution is that the deficit angle depends on the brane geometry. We discuss the implication of the solution to the cosmological constant problem. We also comment on a possible problem of inflation model building on codimension two branes.

I discuss scalar brane world cosmological perturbations for a 3-brane world in a maximally symmetric 5D bulk. I show that Mukoyama’s master equations lead, for adiabatic perturbations of a perfect fluid on the brane and for scalar field matter on the brane, to a well-posed problem despite the nonlocal aspect of the boundary condition on the brane. I discuss in relation to the well-posedness the way to specify initial data in the bulk.

We propose a novel scenario to explain the observed cosmological asymmetry between matter and antimatter, based on nonperturbative QCD physics. This scenario relies on a mechanism of separation of quarks and antiquarks in two coexisting phases at the end of the cosmological QCD phase transition: ordinary hadrons (and antihadrons), along with massive lumps (and antilumps) of novel color superconducting phase. The latter would serve as the cosmological cold dark matter. In certain conditions the separation of charge is $C$ and $CP$ asymmetric and can leave a net excess of hadrons over antihadrons in the conventional phase, even if the visible universe is globally baryon symmetric $B=0$. In this case an equal, but negative, overall baryon charge must be hidden in the lumps of novel phase. Because of the small volume occupied by these dense lumps/antilumps of color superconducting phase and the specific features of their interaction with normal matter in hadronic phase, this scenario does not contradict the current phenomenological constrains on presence of antimatter in the visible universe. Moreover, in this scenario the observed cosmological ratio ${\Omega }_{\mathrm{D}\mathrm{M}}\sim {\Omega }_B$ within an order of magnitude finds a natural explanation, as both contributions to $\Omega$ originated from the same physics during the QCD phase transition. The baryon to entropy ratio $n_B/n_{\gamma }\sim {10}^{-10}$ would also be a natural outcome, fixed by the temperature $T_f\lesssim T_{\mathrm{Q}\mathrm{C}\mathrm{D}}$ at which the separation of phases is completed.

Without assuming any specific flavor symmetry and/or any specific mass-matrix forms, it is demonstrated that if an unbroken flavor symmetry exists, we cannot obtain the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix $V$ and the Maki-Nakagawa-Sakata (MNS) lepton mixing matrix $U$ except for those between two families for the case with the completely undegenerated fermion masses, so that we can never give the observed CKM and MNS mixings. Only in the limit of $m_{\nu 1}=m_{\nu 2}$ ($m_d=m_s$), we can obtain three family mixing with an interesting constraint $U_{e3}=0$ ($V_{ub}=0$).

We calculate the photoproduction of heavy quarks in proton-proton collisions at RHIC, Tevatron, and CERN LHC energies, where the photon reaches energies larger than those accessible at DESY-HERA. The integrated cross section and the rapidity distributions for open charm and bottom production are computed employing sound high energy QCD formalisms. For the linear perturbative QCD approaches we consider both the usual collinear factorization and the $k_{\perp }$-factorization formalisms, whereas for the nonlinear QCD (saturation) calculations one considers the Golec-Biernat-Wüsthoff and the Iancu-Itakura-Munier parametrizations for the dipole cross section within the color dipole picture.

The linear $k_{\perp }$ factorization is part and parcel of the perturbative QCD description of high-energy hard processes off free nucleons. In the case of heavy nuclear targets the very concept of nuclear parton density becomes ill-defined as exemplified by the recent derivation [N. N. Nikolaev, W. Schäfer, B. G. Zakharov, and V. R. Zoller, J. Exp. Theor. Phys. 97, 441 (2003).] of nonlinear nuclear $k_{\perp }$ factorization for forward dijet production in deep inelastic scattering off nuclei. Here we report a derivation of the related breaking of $k_{\perp }$ factorization for single-jet processes. We present a general formalism and apply it to several cases of practical interest: open-charm and quark and gluon-jet production in the central to beam fragmentation region of ${\gamma }^{*}p$, ${\gamma }^{*}A$, $pp$, and $pA$ collisions. We show how the pattern of $k_{\perp }$ factorization breaking and the nature and number of exchanged nuclear pomerons do change within the phase space of produced quark and gluon jets. As an application of the nonlinear $k_{\perp }$ factorization we discuss the Cronin effect. Our results are also applicable to the $p_{\perp }$ dependence of the Landau-Pomeranchuk-Migdal effect for, and nuclear quenching of, jets produced in the proton hemisphere of $pA$ collisions.

The approximate stress-energy tensor of the conformally invariant massless spin-$1/2$ field in the Hartle-Hawking state in the Schwarzschild spacetime is constructed. It is shown that by solving the conservation equation in conformal space and utilizing the regularity conditions in a physical metric one obtains the stress-energy tensor that is in good agreement with the numerical calculations. The backreaction of the quantized field upon the spacetime metric is briefly discussed.

The landscape of string/M theory is surveyed over a large class of type IIB flux compactification vacua. We derive a simple formula for the average size of the gauge group rank on the landscape under assumptions that we clearly state. We also compute the rank under the restriction of small cosmological constant, and find a slight increase. We discuss how this calculation could impact proton stability by computing the suppression factor for the number of vacua with additional gauge group rank that could be used to protect the proton. Finally, we present our views on the utility and limitations of landscape averages, especially in the context of this analysis.

In this paper we examine $\Phi$-derivable approximations in QED. General theorems tell us that the gauge dependence of the $n$-loop $\Phi$-derivable approximation shows up at order $g^{2n}$ where $g$ is the coupling constant. We consider the gauge dependence of the two-loop $\Phi$-derivable approximation to the Debye mass and show that it is of order $e^4$ as expected. We solve the three-loop $\Phi$-derivable approximation in QED by expanding sum-integrals in powers of $e^2$ and $m/T$, where $m$ is the Debye mass which satisfies a variational gap equation. The results for the pressure and the Debye mass are accurate to order $e^5$.

Renormalization group in the internal space consists of the gradual change of the coupling constants. Functional evolution equations corresponding to the change of the mass or the coupling constant are presented in the framework of a scalar model. The evolution in the mass which yields the functional generalization of the Callan-Symanzik equation for the one-particle irreducible effective action is given in its renormalized, cutoff-independent form. The evolution of the coupling constant generates an evolution equation for the two-particle irreducible effective action.

In supersymmetric gluodynamics ($\mathcal{N}=1$ super-Yang-Mills theory), we show that the spectral functions induced by the nonchiral operator $\mathrm{T}\mathrm{r}(G_{\alpha \beta }{\overline{\lambda }}^2)$ are fully degenerate in the $J^{PC}=1^{\pm -}$ channels. The above operator is related to $\mathcal{N}=1/2$ generalization of SUSY. Using the planar equivalence, this translates into the statement of degeneracy between the mesons produced from the vacuum by the operators $(\overline{\Psi }\overrightarrow{E}\Psi +i\overline{\Psi }\overrightarrow{B}{\gamma }^5\Psi )$ and $(\overline{\Psi }\overrightarrow{B}\Psi -i\overline{\Psi }\overrightarrow{E}{\gamma }^5\Psi )$ in one-flavor QCD, up to $1/N$ corrections. Here $\Psi$ is the quark field, and $\overrightarrow{E},\overrightarrow{B}$ are chromoelectric/chromomagnetic fields, respectively.

A choice of first-order variables for the characteristic problem of the linearized Einstein equations is found which casts the system into manifestly well-posed form. The concept of well-posedness for characteristic problems invoked is that there exists an a priori estimate of the solution of the characteristic problem in terms of the data. The notion of manifest well-posedness consists of an algebraic criterion sufficient for the existence of the estimates, and is to characteristic problems as symmetric hyperbolicity is to Cauchy problems. Both notions have been made precise elsewhere.

A method is presented to construct initial data for Einstein's equations as a superposition of a gravitational wave perturbation on an arbitrary stationary background spacetime. The method combines the conformal thin sandwich formalism with linear gravitational waves, and allows detailed control over characteristics of the superposed gravitational wave like shape, location and propagation direction. It is furthermore fully covariant with respect to spatial coordinate changes and allows for very large amplitude of the gravitational wave.