119018357
On Root Multiplicities of Some Hyperbolic Kac–Moody Algebras
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.
18392219
AFFINE SOLITONS: A RELATION BETWEEN TAU FUNCTIONS, DRESSING AND BÄCKLUND TRANSFORMATIONS
We reconsider the construction of solitons by dressing transformations in the sine-Gordon model. We show that the N-soliton solutions are in the orbit of the vacuum, and we identify the elements in the dressing group which allow us to build the N-soliton solutions from the vacuum solution. The dressed τ functions can be computed in two different ways: either using adjoint actions in the affine Lie algebra , and this gives the relation with the Backlund transformations, or using the level-one representations of the affine Lie algebra , and this directly gives the formulae for the τ functions in terms of vertex operators.
120400467
An Introduction to Yangian Symmetries
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.
2671755
Logarithmic Yangians in WZW Models
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.
17641456
Spin-Charge Separation and the Spin Quantum Hall Effect
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.
15502559
Anomalous scaling in the N-point functions of a passive scalar.
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.
209868526
Measurements of the Semileptonic Decays anti-B ---> D l anti-nu and anti-B ---> D* l anti-nu Using a Global Fit to D X l anti-nu Final States
125425400
Measurement of the branching ratio Gamma(D($s$)*+ $\to D_s + \pi^0$ ) / Gamma(D($s$)*+ $\to D_s + \gamma^{)}$
123828218
Measurement of the $B^0 \to \pi^{-} \ell^{+} \nu$ and $B^{+} \to \pi^0 \ell^{+} \nu$ branching fractions and determination of $|V_{ub}|$ in $\upsilon_{4S} \to B \bar{B}$ events tagged by a fully reconstructed $B$ meson
The authors report preliminary measurements of the charmless exclusive semileptonic branching fractions of the B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu} and B{sup +} {yields} {pi}{sup 0}{ell}{sup +}{nu} decays, based on 211 fb{sup -1} of data collected at the {Upsilon}(4S) resonance by the BABAR detector. In events in which the decay of one B meson to a hadronic final state is fully reconstructed, the semileptonic decay of the second B meson is identified by the detection of a charged lepton and a pion. They measure the partial branching fractions for B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu} and B{sup +} {yields} {pi}{sup 0}{ell}{sup +}{nu} in three regions of the invariant mass squared of the lepton pair, and they obtain the total branching fractions {Beta}(B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu}) = (1.14 {+-} 0.27{sub stat} {+-} 0.17{sub syst}) x 10{sup -4} and {Beta}(B{sup +} {yields} {pi}{sup 0}{ell}{sup +}{nu}) = (0.86 {+-} 0.22{sub stat} {+-} 0.11{sub syst}) x 10{sup -4}. Using isospin symmetry, they measure the combined total branching fraction {Beta}(B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu}) = (1.28 {+-} 0.23{sub stat} {+-} 0.16{sub syst}) x 10{sup -4}. Theoretical predictions of the form-factor are used to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |V{submore » ub}| = (3.7 {+-} 0.3{sub stat} {+-} 0.2{sub syst{sub -0.5FF}{sup +0.8}}) x 10{sup -3}, where the last uncertainty is due to the form-factor normalization.« less
199681180
A Measurement of the B0 - anti-B0 oscillation frequency and determination of flavor tagging efficiency using semileptonic and hadronic B0 decays
120104270
Operation of the Cherenkov detector DIRC of BABAR at high luminosity
The DIRC (acronym for Detection of Internally Reflected Cherenkov (light)) is the ring imaging Cherenkov detector of the BABAR detector at the PEP-II ring of SLAC. It provides the identification of pions, kaons and protons for momenta up to 4 GeV/c with high efficiency. This is needed to reconstruct CP-violating B-decay final states and to provide B-meson flavour tagging for time dependent asymmetry measurements. The DIRC radiators consists of long rectangular bars made of synthetic fused silica and the photon detector is a water tank equipped with an array of 10.752 conventional photomultipliers. At the end of the year 2000 BABAR has recorded about 22 million B~B pairs reaching the design luminosity of L=3/spl middot/10/sup 33//cm/sup 2/s. The ability to keep the beam background level low at highest collision rates and the long term reliability of the DIRC components during continuous data taking are requirements of BABAR to accomplish its physics program.