In earlier work, $\mathcal{N}=(1,1)$ super Yang-Mills theory in two dimensions was found to have several interesting properties, though these properties could not be investigated in any detail. In this paper we analyze several of these properties. We investigate the spectrum of the theory, and we calculate the masses of the low-lying states using supersymmetric discrete light-cone quantization (SDLCQ) and obtain their continuum values. The spectrum exhibits an interesting pattern of masses, which we discuss along with a toy model for this pattern which might allow an understanding of the entire spectrum. We confirm an earlier speculation that the mass gap in this theory goes to zero at infinite resolution. We also discuss how the average number of partons in the bound states grows with increasing resolution. As a significant step toward a proof that SDLCQ must be supersymmetric, we determine the numbers of fermions and bosons in the $\mathcal{N}=(1,1)$ and $\mathcal{N}=(2,2)$ theories in each symmetry sector, as functions of the resolution, and show that these numbers are equal.

We present a new method for determining the renormalization of Green functions to all orders in perturbation theory, which we call the displacement operator formalism, or the $D$ formalism, in short. This formalism exploits the fact that the renormalized Green functions may be calculated by displacing by an infinite amount the renormalized fields and parameters of the theory with respect to the unrenormalized ones. With the help of this formalism, we are able to obtain the precise form of the deformations induced to the Nielsen identities after renormalization, and thus derive the exact dependence of the renormalized Green functions on the renormalized gauge-fixing parameter to all orders. As a particular nontrivial example, we calculate the gauge dependence of $\tan \beta$ at two loops in the framework of an Abelian-Higgs model, using a gauge-fixing scheme that preserves the Higgs-boson low-energy theorem for off-shell Green functions. Various possible applications and future directions are briefly discussed.

We have studied the cosmological evolution of domain wall networks in two, three, and four spatial dimensions using high-resolution field theory simulations. The dynamical range and number of our simulations is larger than in previous works, but does not allow us to exclude previous hints of deviations to the naively expected scale-invariant evolution. These results therefore suggest that the approach of domain wall networks to linear scaling is a much slower process than that of cosmic strings, which has been previously characterized in detail.

We investigate a possible asymmetry in the statistical properties of the cosmic microwave background temperature field and to do so we construct an estimator aiming at detecting a dipolar modulation. Such a modulation is found to induce correlations between multipoles with $\Delta \ell =1$. We proceed in two steps. First, assuming that the only possible contaminant comes from our galaxy, we build an estimator using an azimuthally symmetric galactic mask for which analytical construction is possible. Applying this estimator to the V and W bands of the Wilkinson Microwave Anisotropy Probe (WMAP) data, we found an apparent detection in the V band. Further investigation of the foregrounds and the use of the kp0 mask provided by the WMAP team shows that, when the main extragalactic sources are properly removed, no significant detection remains.

We propose an alternative cosmological model in which our observable Universe is an island in a cosmological constant sea. Initially the Universe is filled with cosmological constant of the currently observed value but is otherwise empty. In this eternal or semieternal de Sitter spacetime, we show that local quantum fluctuations (upheavals) can violate the null energy condition and create islands of matter. The perturbation spectra of quantum fields other than that responsible for the upheaval, are shown to be scale invariant. With further cosmic evolution the island disappears and the local Universe returns to its initial cosmological constant dominated state.

To systematically analyze the dynamical implications of the matter content in cosmology, we generalize earlier dynamical systems approaches so that perfect fluids with a general barotropic equation of state can be treated. We focus on locally rotationally symmetric Bianchi type IX and Kantowski-Sachs orthogonal perfect fluid models, since such models exhibit a particularly rich dynamical structure and also illustrate typical features of more general cases. For these models, we recast Einstein’s field equations into a regular system on a compact state space, which is the basis for our analysis. We prove that models expand from a singularity and recollapse to a singularity when the perfect fluid satisfies the strong energy condition. When the matter source admits Einstein’s static model, we present a comprehensive dynamical description, which includes the qualitative asymptotic behavior, of models in the neighborhood of the Einstein model; the results refute earlier claims about “homoclinic phenomena and chaos.” We also discuss aspects of the global dynamics of models; in particular, we give criteria for the collapse to a singularity, and we describe when models expand forever to a state of infinite dilution; possible initial and final states are analyzed. Numerical investigations complement the analytical results.

In this paper, a braneworld black hole is studied as a gravitational lens, using the strong field limit to obtain the positions and magnifications of the relativistic images. Standard lensing and retrolensing situations are analyzed in a unified setting, and the results are compared with those corresponding to the Schwarzschild black hole lens. The possibility of observing the strong field images is discussed.

We discuss full-sky convolution of the instrumental beam with the CMB sky signal in CMB single-dish and interferometry experiments using the method [A. Challinor et al., Phys. Rev. D 62, 123002 (2000); B. D. Wandelt and K. M. Górski, Phys. Rev. D 63, 123002 (2001).] that the measured temperature and polarization anisotropies are defined globally on the group manifold of the three-dimensional rotation by means of Wigner $D$ functions. We rederive the anisotropy and polarization correlation functions incorporated with asymmetric window functions, which are then explicitly calculated for a single-dish elliptical Gaussian beam and an interferometric Gaussian beam.

Modelling of the weak lensing of the CMB will be crucial to obtain correct cosmological parameter constraints from forthcoming precision CMB anisotropy observations. The lensing affects the power spectrum as well as inducing non-Gaussianities. We discuss the simulation of full-sky CMB maps in the weak lensing approximation and describe a fast numerical code. The series expansion in the deflection angle cannot be used to simulate accurate CMB maps, so a pixel remapping must be used. For parameter estimation accounting for the change in the power spectrum but assuming Gaussianity is sufficient to obtain accurate results up to Planck sensitivity using current tools. A fuller analysis may be required to obtain accurate error estimates and for more sensitive observations. We demonstrate a simple full-sky simulation and subsequent parameter estimation at Planck-like sensitivity. The lensed CMB simulation and parameter estimation codes are publicly available.

The interaction of the charmonium resonances $J/\psi$ and ${\psi }^{\prime }$ with nucleons at low energies is considered using the multipole expansion and low-energy theorems in QCD. A lower bound is established for the relevant gluonic operator average over the nucleon. As a result we find the discussed interaction to be significantly stronger than previously estimated in the literature. In particular we conclude that the cross section of the $J/\psi$ - nucleon elastic scattering at the threshold is very likely to exceed 17 mb and that existence of bound states of the $J/\psi$ in light nuclei is possible. For the ${\psi }^{\prime }$ resonance we estimate even larger elastic scattering cross section and also a very large cross section of the process ${\psi }^{\prime }+N\to \psi +N$ giving rise to the decay width of tens of MeV for the ${\psi }^{\prime }$ resonance in heavy nuclei.

The role of intrinsic $\mathit{k}{}_{\perp }$ in inclusive and semi-inclusive Deep Inelastic Scattering processes ($\ell p\to \ell hX$) is studied with exact kinematics within QCD parton model at leading order; the dependence of the unpolarized cross section on the azimuthal angle between the leptonic and the hadron production planes (Cahn effect) is compared with data and used to estimate the average values of $k_{\perp }$ both in quark distribution and fragmentation functions. The resulting picture is applied to the description of the weighted single spin asymmetry $A_{UT}^{\sin ({\varphi }_{\pi }-{\varphi }_S)}$ recently measured by the HERMES collaboration at DESY; this allows to extract some simple models for the quark Sivers functions. These are compared with the Sivers functions which succeed in describing the data on transverse single spin asymmetries in $p^{\uparrow }p\to \pi X$ processes; the two sets of functions are not inconsistent. The extracted Sivers functions give predictions for the COMPASS measurement of $A_{UT}^{\sin ({\varphi }_{\pi }-{\varphi }_S)}$ in agreement with recent preliminary data, while their contribution to HERMES $A_{UL}^{\sin {\varphi }_{\pi }}$ is computed and found to be small. Predictions for $A_{UT}^{\sin ({\varphi }_K-{\varphi }_S)}$ for kaon production at HERMES are also given.

If the recently discovered charmoniumlike state $X(3872)$ is a loosely bound $S$-wave molecule of the charm mesons $D^0{\overline{D}}^{*0}$ or $D^{*0}{\overline{D}}^0$, it can be produced through the weak decay of the $B$ meson into $D^0{\overline{D}}^{*0}K$ or $D^{*0}{\overline{D}}^{0}K$ followed by the coalescence of the charm mesons at a long-distance scale set by the scattering length of the charm mesons. The long-distance factors in the amplitude for the decay $B\to XK$ are determined by the binding energy of $X$, while the short-distance factors are essentially determined by the amplitudes for $B\to D^0{\overline{D}}^{*0}K$ and $B\to D^{*0}{\overline{D}}^{0}K$ near the thresholds for the charm mesons. We obtain a crude determination of the short-distance amplitudes by analyzing data from the BABAR Collaboration on the branching fractions for $B\to {\overline{D}}^{(*)}{D}^{(*)}K$ using a factorization assumption, heavy-quark symmetry, and isospin symmetry. The resulting order-of-magnitude estimate of the branching fraction for $B^{+}\to X{K}^{+}$ is compatible with observations provided that $J/\psi {\pi }^{+}{\pi }^{-}$ is a major decay mode of the $X$. The branching fraction for $B^0\to X{K}^0$ is predicted to be suppressed by more than an order of magnitude compared to that for $B^{+}\to X{K}^{+}$.

We consider the top-anti-top invariant mass distributions for production of unpolarized and polarized top quark pairs at LHC, in the theoretical framework of the MSSM. Assuming a “moderately” light SUSY scenario, we derive the leading logarithmic electroweak contributions at one loop in a region of large invariant mass, $M_{t\overline{t}}\simeq 1\mathrm{TeV}$, for the unpolarized differential cross section $d\sigma /d{M}_{t\overline{t}}$ and for the differential longitudinal top polarization asymmetry $A_t(M_{t\overline{t}})$. We perform a realistic evaluation of the expected uncertainties of the two quantities, both from a theoretical and from an experimental point of view, and discuss the possibility of obtaining, from accurate measurements of the two mass distributions, stringent consistency tests of the model, in particular identifications of large $\tan \beta$ effects.

Numerical simulations show that a long-range scalar interaction in a single species of massive dark matter particles causes voids between the concentrations of large galaxies to be more nearly empty, suppresses accretion of intergalactic matter onto galaxies at low redshift, and produces an early generation of dense dark matter halos. These three effects, in moderation, seem to be improvements over the $\Lambda$CDM model predictions for cosmic structure formation. Because the scalar interaction in this model has negligible effect on laboratory physics and the classical cosmological tests, it offers an observationally attractive example of cosmology with complicated physics in the dark sector, notably a large violation of the weak equivalence principle.

Recent work suggests that the cosmic-ray spectrum may be dominated by Galactic sources up to $\sim {10}^{17.5}$ eV, and by an extra-Galactic component beyond, provided this latter cuts off below the transition energy. Here it is shown that this cut-off could be interpreted in this framework as a signature of extra-galactic magnetic fields with equivalent average strength $B$ and coherence length $l_{\mathrm{c}}$ such that $B\sqrt{l_{\mathrm{c}}}\sim 2-3·{10}^{-10}\mathrm{G}·{\mathrm{Mpc}}^{1/2}$, assuming $l_{\mathrm{c}}<r_{\mathrm{L}}$ (Larmor radius at $\lesssim {10}^{17}$ eV) and continuously emitting sources with density ${10}^{-5}{\mathrm{Mpc}}^{-3}$. The extra-Galactic flux is suppressed below $\sim {10}^{17}$ eV as the diffusive propagation time from the source to the detector becomes larger than the age of the Universe.

In this work we extend our previously developed formalism of Newtonian multifluid hydrodynamics to allow for coupling between the fluids and the electromagnetic and gravitational field. This is achieved within the convective variational principle by using a standard minimal coupling prescription. In addition to the conservation of total energy and momentum, we derive the conservation of canonical vorticity and helicity, which generalize the corresponding conserved quantities of uncharged fluids. We discuss the application of this formalism to electrically conducting systems, magnetohydrodynamics and superconductivity. The equations of electric conductors derived here are more general than those found in the standard description of such systems, in which the effect of entrainment is overlooked, despite the fact that it will generally be present in any conducting multiconstituent system.

We study the deconfining phase transition in $SU(N)$ gauge theories at nonzero temperature using a matrix model of Polyakov loops. The most general effective action, including all terms up to two spatial derivatives, is presented. At large $N$, the action is dominated by the loop potential: following Aharony et al., we show how the Gross-Witten model represents an ultracritical point in this potential. Although masses vanish at the Gross-Witten point, the transition is of first order, as the fundamental loop jumps only halfway to its perturbative value. Comparing numerical analysis of the $N=3$ matrix model to lattice simulations, for three colors the deconfining transition appears to be near the Gross-Witten point. To see if this persists for $N\ge 4$, we suggest measuring within a window $\sim 1/N^2$ of the transition temperature.

We present a measurement of the cross section for $Z$ production times the branching fraction to $\tau$ leptons, $\sigma ·\mathrm{Br}(Z\to {\tau }^{+}{\tau }^{-})$, in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ in the channel in which one $\tau$ decays into $\mu {\nu }_{\mu }{\nu }_{\tau }$, and the other into $\mathrm{hadrons}+{\nu }_{\tau }$ or $e{\nu }_e{\nu }_{\tau }$. The data sample corresponds to an integrated luminosity of $226{\mathrm{pb}}^{-1}$ collected with the D0 detector at the Fermilab Tevatron collider. The final sample contains 2008 candidate events with an estimated background of 55%. From this we obtain $\sigma ·\mathrm{Br}(Z\to {\tau }^{+}{\tau }^{-})=237\pm 15(\mathrm{\text{stat}})\pm 18(\mathrm{\text{sys}})\pm 15(\mathrm{\text{lum}})\mathrm{pb}$, in agreement with the standard model prediction.

The Universe might experience many cycles with different vacua. The slow-roll inflation may be preceded by kinetic-dominated contraction occurring in “adjacent” vacua during some cycles. In this report we briefly show this phenomenon may lead to a cutoff of primordial power spectrum, which is mildly preferred by WMAP data. Thus in some sense the cosmic microwave background at large angular scale might encode the information of other vacua.