We construct perturbative frameworks for studying nonequilibrium spin-polarized quark matter. We employ the closed-time-path formalism and use the gradient approximation in derivative expansion. After constructing self-energy-part resummed quark and gluon propagators, we formulate two kinds of mutually equivalent perturbative frameworks: The first one is formulated on the basis of the initial-particle distribution function, and the second one is formulated on the basis of a “physical” particle distribution function. In the course of the construction of the second framework, the generalized Boltzmann equations and their relatives directly come out, which describe the evolution of the system. The frameworks are relevant to the study of a magnetic character of quark matter, e.g., possible quark stars.

Superfield realizations of Lorentz-violating extensions of the Wess-Zumino model are presented. These models retain supersymmetry but include terms that explicitly break the Lorentz symmetry. The models can be understood as arising from superspace transformations that are modifications of the familiar one in the Lorentz-symmetric case.

In the context of the littlest Higgs (LH) model, we consider the Higgsstrahlung process $e^{+}{e}^{-}\to \mathrm{ZH}.\mathrm{}$ We find that the correction effects on this process mainly come from the heavy photon $B^{\prime }.$ If we take the mixing angle parameter c in the range of 0.75–1, the contributions of the heavy gauge boson $W_3^{\prime }$ are larger than 6%. In most of the parameter space, the deviation of the total production cross section ${\sigma }^{\mathrm{tot}}$ from its SM value is larger than 5%, which may be detected in future high energy $e^{+}{e}^{-}$ collider (LC) experiments. The future LC experiments could test the LH model by measuring the cross section of the process $e^{+}{e}^{-}\to \mathrm{ZH}.\mathrm{}$

In the framework of the top-color-assisted-technicolor (TC2) model, we study a flavor-changing neutral top-pion production process $\gamma \overrightarrow{\gamma }t\overline{c}{\Pi }_t^0.$ The study shows that there exists a resonance effect which can enhance the cross section up to a few fb and even tens of fb. For a yearly luminosity $100{\mathrm{fb}}^{-1}$ at future linear colliders, there might be hundreds or even thousands of events produced. On the other hand, the background of such a flavor-changing process is very clean due to the Glashow-Iliopoulos-Maiani mechanism in the standard model. With such sufficient events and a clean background, a neutral top-pion could be detected at future linear colliders with a high center of energy and luminosity. Our study provides a possible way to test the TC2 model.

The $p_T$ spectra for direct $J/\psi$ and ${\psi }^{\prime }$ hadroproduction at Fermilab Tevatron energy are calculated within the framework of the NRQCD formalism and the fragmentation model in the collinear parton model as well as in the $k_T$-factorization approach. We describe the Collider Detector at Fermilab data and obtain a good agreement between the predictions of the parton model and the $k_T$-factorization approach. We perform the calculations using the relevant leading order in ${\alpha }_s$ hard amplitudes and taking equal values of the long-distance matrix elements for both models.

This article brings attention to what is knowable from perturbative QCD theory on two-parton distribution functions in the light of recent CDF measurements [Phys. Rev. D 56, 3811 (1997)] of the inclusive cross section for double parton scattering. It is shown that the solution of generalized Lipatov-Altarelli-Parisi-Dokshitzer equations for the two-parton distributions is not at all the product of two single-parton distributions, which is usually applied to the current analysis as an ansatz.

In the framework of heavy quark effective theory we use QCD sum rules to calculate the masses of the $\overline{c}{s(0\mathrm{}}^{+}{,1\mathrm{}}^{+})$ and ${(1\mathrm{}}^{+}{,2\mathrm{}}^{+})$ excited states. The results are consistent with the states $D_{\mathrm{sJ}}\mathrm{}\left(2317\right)\mathrm{}$ and $D_{\mathrm{sJ}}\mathrm{}\left(2460\right)\mathrm{}$ observed by BABAR and CLEO being the $0^{+}$ and $1^{+}$ states in the $j_l={\frac{1}{2}}^{+}$ doublet.

We investigate the analytic structure of the Borel-summed perturbative QCD amplitudes in the complex plane of the coupling constant. Using the method of inverse Mellin transform, we show that the prescription dependent Borel-Laplace integral can be cast, under some conditions, into the form of a dispersion relation in the a plane. We also discuss some recent works relating resummation prescriptions, renormalons and nonperturbative effects, and show that a method proposed recently for obtaining QCD nonperturbative condensates from perturbation theory is based on special assumptions about the analytic structure in the coupling plane that are not valid in QCD.

We prove a factorization theorem in QCD for the color suppressed decays $B^0\to D^0{M}^0$ and $B^0\to D^{*0}{M}^0$ where M is a light meson. Both the color-suppressed and W-exchange or annihilation amplitudes contribute at lowest order in ${\Lambda }_{\mathrm{QCD}}/Q$ where $Q=\{m_b{,m}_c{,E}_{\pi }\},$ so no power suppression of annihilation contributions is found. A new mechanism is given for generating nonperturbative strong phases in the factorization framework. Model-independent predictions that follow from our results include the equality of the $B^0\to D^0{M}^0$ and $B^0\to D^{*0}{M}^0$ rates and the equality of nonperturbative strong phases between isospin amplitudes, ${\delta }^{\mathrm{}\left(\mathrm{DM}\right)\mathrm{}}={\delta }^{{(D}^{*}M)}.$ Relations between amplitudes and phases for $M=\pi ,\rho$ are also derived. These results do not follow from large $N_c$ factorization with heavy quark symmetry.

A deficit of atmospheric ${\nu }_{\mu }$ events, consistent with the hypothesis of neutrino oscillations, is observed in the 5.90 kiloton-year fiducial exposure of the Soudan 2 detector. An unbinned maximum likelihood analysis of the neutrino $L/E$ distribution has been carried out using the Feldman-Cousins prescription. The probability of the no oscillation hypothesis is $5.8\times {10}^{-4}.$ The 90% confidence allowed region in the ${\sin }^{2}2\theta ,\Delta m^2$ plane is presented. The region includes the 90% confidence allowed region of the Super-K experiment.

We study the effect of the thermal width of $\pi$ on the spectral function of $\sigma$ applying a resummation technique called the optimized perturbation theory at finite temperature (T) to the $O\left(4\right)\mathrm{}$ linear sigma model. In order to take into account a finite thermal width of $\pi ,$ we replace the internal pion mass in the self-energy of $\sigma$ with that of the complex pole found in a previous paper. The obtained spectral function for $T\gtrsim 100\mathrm{MeV}$ turns out to possess two broad peaks. Although a sharp peak at $\overrightarrow{\sigma }\pi \pi$ threshold was observed in the one-loop calculation without the pion thermal width, the peak is shown to be smeared out. We also search for the poles of the $\sigma$ propagator and analyze the behavior of the spectral function with these poles.

We show that shape moduli in submillimeter extra dimensional scenarios, addressing the gauge hierarchy problem, can dominate the energy density of the Universe today. In our scenario, the volume of the extra dimensions is stabilized at a sufficiently high scale to avoid conflicts with nucleosynthesis and solar-system precision gravity experiments, while the shape moduli remain light but couple extremely weakly to brane-localized matter and easily avoid these bounds. Nonlocal effects in the bulk of the extra dimensions generate a potential for the shape moduli. The potential has the right form and order of magnitude to account for the present day cosmic acceleration, in a way analogous to models of quintessence as a pseudo Nambu-Goldstone boson.

Space-based experiments offer sensitivity to numerous unmeasured effects involving Lorentz and $\mathrm{CPT}$ violation. We provide a classification of clock sensitivities and present explicit expressions for time variations arising in such experiments from nonzero coefficients in the Lorentz- and $\mathrm{CPT}$-violating Standard-Model Extension.

We calculate the spectrum of the linearized supergravity around the maximally supersymmetric pp-wave background in eleven dimensions. The resulting spectrum agrees with that of zero-mode Hamiltonian of a supermembrane theory on the pp-wave background. We also discuss the connection with the Kaluza-Klein zero modes of an ${\mathrm{AdS}}_4\times {\mathrm{S}}^7$ background.

We propose a technique, using interferometry of Bose-Einstein condensed alkali atoms, for the detection of submicron-range forces. It may extend present searches at 1 micron by 6 to 9 orders of magnitude, deep into the theoretically interesting regime of 1000 times gravity. We give several examples of both four-dimensional particles (moduli), as well as higher-dimensional particles—vectors and scalars in a large bulk—that could mediate forces accessible by this technique.

In this paper we obtain a space-time generated by a timelike current-carrying superconducting screwed cosmic string (TCSCS). This gravitational field is obtained in a modified scalar-tensor theory in the sense that torsion is taken into account. We show that this solution is compatible with a torsion field generated by the scalar field $\phi .$ The analysis of the gravitational effects of a TCSCS shows up that the torsion effects that appear in the physical frame of Jordan-Fierz type can be described in a geometric form given by contorsion term plus a symmetric part which contains the scalar gradient. As an important application of this solution, we consider the linear perturbation method developed by Zel’dovich, investigate the accretion of cold dark matter due to the formation of wakes when a TCSCS moves with speed $v,$ and discuss the role played by torsion. Our results are compared with those obtained for cosmic strings in the framework of scalar-tensor theories without taking torsion into account.

We give a detailed description of the constant mean curvature foliations in Schwarzschild spacetime, show that the lapse collapses exponentially, and compute the exponent.

A hypothetical violation of Lorentz invariance in the electrons’ equation of motion (expressed within the Lorentz-violating extension of the standard model) leads to a change in the geometry of crystals and thus shifts the resonance frequency of an electromagnetic cavity. This allows experimental tests of Lorentz invariance of the electron sector of the standard model. The material dependence of the effect allows us to separate it from an additional shift caused by Lorentz violation in electrodynamics, and to place independent limits on both effects. From present experiments, upper limits on Lorentz violation in the electrons’ kinetic energy term are deduced.

We evaluate the differential cross section for the electroproduction of lepton pairs off a polarized nucleon target in the generalized Bjorken region to leading power accuracy in hard momentum. We discuss the importance of this process for phenomenology of generalized parton distributions. Special attention is given to the sensitivity of physical observables, i.e., diverse asymmetries, to their dependence on scaling variables that allows us to map directly the functional two-dimensional surface of generalized parton distributions.