Vertex operators and fusion rules in the free field realizations of WZNW models
We study the representation of chiral vertex operators for sl(N) WZNW models in the free field formalism. Exploiting the underlying quantum group structure of the free field resolution, we reduce the problem of constructing the infinite number of components of a chiral vertex to that of finding a single vector in a finite dimensional irreducible representation of U q ( sl (N)) . In particular this provides a new, purely algebraic, characterization of the fusion rules. We briefly summarize the analogous construction for finite dimensional algebras and use it as a guide. Our discussion is illustrated by explicit examples of vertices in sl(2) and sl(3) WZNW models.

title: Free Field Approach to 2-Dimensional Conformal Field Theories

title: Theoretical problems in nonsymmetric gravitational theory.
abstract: It has recenty been noted that the nonsymmetric metric model of gravity faces severe observational constraints. We show here that it is also subject to physically unacceptable formal difficulties even as an effective field theory: When expanded about a Riemannian background, the model exhibits curvature-coupled negative-energy (ghost) modes and unacceptable asymptotic behavior.

title: Seiberg--Witten Monopoles in Three Dimensions
abstract: Dimensional reduction of the Seiberg--Witten equations leads to the equations of motion of a U(1) Chern--Simons theory coupled to a massless spinorial field. A topological quantum field theory is constructed for the moduli space of gauge equivalence classes of solutions of these equations. The Euler characteristic of the moduli space is obtained as the partition function which yields an analogue of Casson's invariant.A mathematically rigorous definition of the invariant isdeveloped for homology spheres using the theory of spectral flow ofself-adjoint Fredholm operators.

title: N=2 minimal models on Riemann surfaces
abstract: We give a general formalism for the computation of conformal blocks for N =2 minimal models on arbitrary Riemann surfaces. We exploit the factorization of N =2 minimal models as (parafermion) × ( c =1 rational boson), obtaining the parafermion contribution by truncating thez SU(2) k WZNW models discussed in one of our previous papers. We conclude by giving the two-loop characters.

title: On the W-Gravity Spectrum and Its G-Structure
abstract: We present results for the BRST cohomology of W[g] minimal models coupled to W[g] gravity, as well as scalar fields coupled to W[g] gravity. In the latter case we explore an intricate relation to the (twisted) g cohomology of a product of two twisted Fock modules.

title: First measurement of the CP-violating phase in $B_s^0 \to \phi \phi$ decays
abstract: A first flavour-tagged measurement of the time-dependent CP-violating asymmetry in $B_s^0 \to \phi\phi$ decays is presented. In this decay channel, the CP-violating weak phase arises due to CP violation in the interference between $B_s^0$-$\bar{B}_s^0$ mixing and the $b \to s \bar{s} s $ gluonic penguin decay amplitude. Using a sample of $pp$ collision data corresponding to an integrated luminosity of $1.0\; fb^{-1}$ and collected at a centre-of-mass energy of $7 \rm TeV$ with the LHCb detector, $880\ \B_s^0 \to \phi\phi$ signal decays are obtained. The CP-violating phase is measured to be in the interval [-2.46, -0.76] \rm rad$ at 68% confidence level. The p-value of the Standard Model prediction is 16%.

title: A study of lithium deuteride as a material for a polarized target
abstract: Experiment E155 at the Stanford Linear Accelerator Center (SLAC) measured the spin-dependent structure of the proton and neutron, using for the first time 6 LiD as the polarized deuteron target material in a high-energy electron beam. This compound provides a significantly higher dilution factor than any other solid deuteron target material currently used in high-energy physics experiments. Results of the polarization behavior of the 6 LiD target material before and after exposure to the 50 GeV/ c electron beam used in E155 are presented.

title: Model calculation of nucleon structure functions
abstract: Deep inelastic polarized and unpolarized structure functions for a free nucleon are obtained in a modified center-of-mass bag model, which includes the symmetry-breaking effects from spin-dependent interactions. The quark distribution functions, calculated at [ital Q][sub 0][sup 2][congruent](0.9 GeV/[ital c])[sup 2], are evolved to a higher [ital Q][sup 2] region and compared with the data and other models. The model gives a reasonable description for the valence part of the structure functions at [ital x][gt]0.3. For the small-[ital x] region, the contributions from the sea are necessary. The spin-dependent effects are important in describing the existing data.

title: Depolarization of dynamically polarized solid targets due to beam heating effects
abstract: The behavior of dynamically polarized targets in the presence of a high intensity electron beam was studied. The nuclear polarization seen by the incident electron beam is lower than the overall measured target polarization by NMR due to beam heating and subsequent depolarization. A correction for this beam-induced depolarization is developed here to correct the measured target polarization for these effects. Furthermore, a model has also been developed to calculate the target depolarization in beam, and optimization of running conditions for future experiments of this nature are discussed based on this model.

title: Negative pion capture on 4He with emission of neutron-proton, neutron-deuteron and neutron-triton pairs
abstract: The energies and opening angles for neutron-proton, and neutron-deuteron pairs emitted after π− capture in 4He have been measured. The data are compared to available theoretical calculations. Both energetic protons and deuterons are strongly correlated in direction with an energetic neutron, being emitted at approximately 180° to each other. A strong enhancement at the high-energy end of the deuteron spectrum is attributed to a strong final state interaction between the remaining two neutrons.