On the Wess-Zumino-Witten models on Riemann surfaces☆
We give a formulation of the Wess-Zumino-Witten models on Riemann surfaces of arbitrary genus in which the Ward identities for the current algebras become complete. It requires twisting the models in a non-abelian way by Lie group elements. The Ward identities are written in terms of twisted Poincare series for Schottky groups and the zero modes of the currents are defined by a Lie derivation acting on the twists. Furthermore, we identify the denominator of the chiral partition function and we argue that both the numerator and the denominator of the partition function satisfy a heat equation on the moduli space.

title: On Root Multiplicities of Some Hyperbolic Kac–Moody Algebras
abstract: Using the coset construction, we compute the root multiplicities at level-3 for some hyperbolic Kac–Moody algebras including the basic hyperbolic extension of A11 and E10.

title: Anomalous scaling in the N-point functions of a passive scalar.
abstract: A recent analysis of the 4-point correlation function of the passive scalar advected by a time-decorrelated random flow is extended to the N-point case. It is shown that all stationary-state inertial-range correlations are dominated by homogeneous zero modes of singular operators describing their evolution. We compute analytically the zero modes governing the N-point structure functions and the anomalous dimensions corresponding to them to the linear order in the scaling exponent of the 2-point function of the advecting velocity field. The implications of these calculations for the dissipation correlations are discussed.

title: Logarithmic Yangians in WZW Models
abstract: A new action of the Yangians in the WZW models is displayed. Its structure is generic and level-independent. This Yangian is the natural extension at the conformal point of the one unraveled in massive theories with current algebras. Hopefully, this new symmetry of WZW models will lead to a deeper understanding of the integrable structure of conformal field theories and their deformations.

title: An Introduction to Yangian Symmetries
abstract: We review some aspects of the quantum Yangians as symmetry algebras of two-dimensional quantum field theories. The plan of these notes is the following: 
 
1 
 
The classical Heisenberg model: 
 
 
 
 
 
 
 
 
 
Non-Abelian symmetries; 
 
 
The generators of the symmetries and the semi-classical Yangians; 
 
 
An alternative presentation of the semi-classical Yangians; 
 
 
Digression on Poisson-Lie groups. 
 
 
Non-Abelian symmetries and the quantum Yangians; 
 
 
The transfer matrix and an alternative presentation of the Yangians; 
 
 
Digression on the double Yangians. 
 
 
 
 
 
2 
 
The quantum Heisenberg chain: 
 
 
 
 
 
 
 
 
 
Non-Abelian symmetries and the quantum Yangians; 
 
 
The transfer matrix and an alternative presentation of the Yangians; 
 
 
Digression on the double Yangians.

title: Spin-Charge Separation and the Spin Quantum Hall Effect
abstract: We use quantum field theory methods to study the network model for the spin quantum hall transition. When the couplings are fine tuned in a certain way, the spin and charge degrees of freedom, corresponding to the su-percurrent algebras su(2) 0 and osp(2|2) −2 respectively, completely decouple. This simpler theory is exactly solvable and some critical exponents are computed and shown to agree with the recent predictions based on percolation. The general network model is shown to be in a different universality class by identifying the attractive direction of the renormalization group flow.

title: Status of the DIRC Detector at Babar: Early Operational Experience
abstract: A novel type of Cherenkov ring imaging particle identification system (DIRC) based on the detection of ring images produced in long, fused silica radiator bars is being used to provide hadronic particle identification in the BABAR detector at PEP-II. The DIRC concept, design, fabrication, and initial performance will be briefly described. The DIRC is now fully commissioned, and has been operating in the BABAR detector on beam line at the PEP-II B Factory since late Spring 1999.

title: On triple focusing dipole magnets
abstract: We present a general, paraxial study of triple focusing (i.e., stigmatic and non-dispersive) index-free dipole magnets. The transcendental equations which describe such magnets lead to a second-degree polynomial equation which we solve analytically. The two solutions of this equation correspond to magnets having either one or no intermediate focal points in the vertical direction. The first-order optical properties of the physical solutions are studied.

title: Search for the decay $B^0 \to \gamma \gamma$

title: Measurement of the branching fractions and CP asymmetries of $B^{-} \to D_{CP} 0 K^{-}$ decays with the BABAR detector
abstract: We present a study of B--> D0(CP)K- decays, where D0(CP) is reconstructed in non-CP (K-pi+), CP-even (K-K+,pi-pi+) and CP-odd (KS0 pi0) eigenstates, based on a sample of about 214 million Y(4S) -> BBbar decays collected with the BABAR detector at the PEP-II e+e- storage ring. We measure the ratios of branching fractions R+ = [Br(B- ->D0_CP+ K-)+Br(B+ ->D0_CP+ K+)]/[Br(B- ->D0 K-)] = 0.87 +/- 0.14(stat) +/- 0.06(syst), R- = [Br(B- ->D0_CP- K-)+Br(B+ ->D0_CP- K+)]/[Br(B- ->D0 K-)] = 0.80 +/- 0.14(stat) +/- 0.08(syst), and the CP asymmetries A_CP+ = 0.40 +/- 0.15 (stat) +/- 0.08 (syst) and A_CP- = 0.21 +/- 0.17 (stat) +/- 0.07 (syst) All results are preliminary.

title: Pseudorapidity distribution of charged particles in diffraction dissociation events at the CERN SPS collider
abstract: The reaction p p → p X was studied as a function of the mass M of the system X at the centre-of-mass energy s = 546 GeV in the kinematical region where diffraction dissociation dominates. The pseudorapidity distribution of charged tracks, produced in the fragmentation of the system X, is well described within the limits of cylindrical phase space. The fragments of the X-system behave very similarly to the products of non-diffractive inelastic collisions at s = M .