117380915
QCD and Hadronic Interactions with Initial-State-Radiation at B-Factories
— The efforts to improve on the precision of the measurement and theoretical prediction of the anomalous magnetic moment of the muon aμ have turned into a test of our understanding of the hadronic contribution to vacuum polarisation. I describe how recent measurements of hadron production in e+e− interactions with initial-state radiation provide precision measurements of the hadron cross section, and have improved on the contribution to the prediction of the value of aμ that dominates the global uncertainty.
125343210
Measurement of the CKM matrix element $|V_{ub}|$ with $B \to \rho e \nu$ 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.
202048438
Branching fraction for $B^{+} \to \pi^0 \ell^{+} \nu$, measured in $\upsilon_{4S} \to B \bar{B}$ events tagged by $B^{-} \to D^0 \ell^{-}$ anti-v ($X$) decays
126404399
Measurements of branching fractions and CP-violating asymmetries in B-meson decays to the charmless two-body states K0 pi+, anti-K0 K+, and K0 anti-K0
160033287
Improved Measurement of CP Violation in Neutral B Decays to c cs
14232793
Multiple Schramm–Loewner Evolutions and Statistical Mechanics Martingales
A statistical mechanics argument relating partition functions to martingales is used to get a condition under which random geometric processes can describe interfaces in 2d statistical mechanics at criticality. Requiring multiple SLEs to satisfy this condition leads to some natural processes, which we study in this note. We give examples of such multiple SLEs and discuss how a choice of conformal block is related to geometric configuration of the interfaces and what is the physical meaning of mixed conformal blocks. We illustrate the general ideas on concrete computations, with applications to percolation and the Ising model
11085461
Spinons in conformal field theory
We study the su(2) conformal field theory in its spinon description, adapted to the yangian invariance. By evaluating the action of the yangian generators on the primary fields, we find a new connection between this conformal field theory and the Calogero-Sutherland model with su(2) spin. We use this connection to describe how the spinons are the quasi-particles spanning the irreducible yangian multiplet, and also to exhibit operators creating the N-spinon highest-weight vectors.
16159393
On symmetries of some massless 2D field theories
Abstract We describe a few aspects of the quantum symmetries of some massless two-dimensional field theories. We discuss their relations with recent proposals for the factorized scattering theories of the massless PCM 1 and O(3) ϑ = π sigma models. We use these symmetries to propose massless factorized S -matrices for the su(2) sigma models with topological terms at any level, alias the PCM k models, and for the su(2)-coset massless flows.
18013997
Yang-Baxter equation in spin chains with long range interactions
We consider the $ su(n) $ spin chains with long range interactions and the spin generalization of the Calogero-Sutherland models. We show that their properties derive from a transfer matrix obeying the Yang-Baxter equation. We obtain the expression of the conserved quantities and we diagonalize them.
119210548
Scrutinizing the Cosmological Constant Problem and a possible resolution
We suggest a new perspective on the Cosmological Constant Problem by scrutinizing its standard formulation. In classical and quantum mechanics without gravity, there is no definition of the zero point of energy. Furthermore, the Casimir effect only measures how the vacuum energy {\it changes} as one varies a geometric modulus. This leads us to propose that the physical vacuum energy in a Friedman-Lema\^itre-Robertson-Walker expanding universe only depends on the time variation of the scale factor $a(t)$. Equivalently, requiring that empty Minkowski space is gravitationally stable is a principle that fixes the ambiguity in the zero point energy. On the other hand, if there is a meaningful bare cosmological constant, this prescription should be viewed as a fine-tuning. 
We describe two different choices of vacuum, one of which is consistent with the current universe consisting only of matter and vacuum energy. The resulting vacuum energy density $\rhovac$ is constant in time and approximately $k_c^2 H_0^2$, where $k_c$ is a momentum cut-off and $H_0$ is the current Hubble constant; for a cut-off close to the Planck scale, values of $\rhovac$ in agreement with astrophysical measurements are obtained. Another choice of vacuum is more relevant to the early universe consisting of only radiation and vacuum energy, and we suggest it as a possible model of inflation.