936612
Strong–weak coupling duality in anisotropic current interactions
Abstract The recently proposed all orders β function for current interactions in two dimensions is further investigated. By using a strong–weak coupling duality of the β function, and some added topology of the space of couplings we are able to extend the flows to arbitrarily large or small scales. Using a nontrivial RG invariant we are able to identify sine-Gordon, sinh-Gordon and Kosterlitz–Thouless phases. We also find an additional phase with cyclic or roaming RG trajectories.
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.
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.
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.
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.
15095539
Search for a dark photon in e(+)e(-) collisions at BABAR.
Dark sectors charged under a new Abelian interaction have recently received much attention in the context of dark matter models. These models introduce a light new mediator, the so-called dark photon (A^{'}), connecting the dark sector to the standard model. We present a search for a dark photon in the reaction e^{+}e^{-}→γA^{'}, A^{'}→e^{+}e^{-}, μ^{+}μ^{-} using 514  fb^{-1} of data collected with the BABAR detector. We observe no statistically significant deviations from the standard model predictions, and we set 90% confidence level upper limits on the mixing strength between the photon and dark photon at the level of 10^{-4}-10^{-3} for dark photon masses in the range 0.02-10.2  GeV. We further constrain the range of the parameter space favored by interpretations of the discrepancy between the calculated and measured anomalous magnetic moment of the muon.
59451840
TPC in gamma-ray astronomy above pair-creation threshold
We examine the performance of a TPC as a -ray telescope above the pair-creation threshold. The contributions to the photon angular resolution are studied and their dependence on energy is obtained. The e ective area per detector unit mass for such a thin detector is the conversion mass attenuation coe cient. The di erential sensitivity for the detection of a point-like source is then derived. Finally, the measurement of track momentum from deflections due to multiple scattering is optimized. These analytical results are exemplified numerically for a few sets of detector parameters. TPCs show an impressive improvement in sensitivity with respect to existing pair-creation-based telescopes in the (MeV - GeV) energy range, even with the modest detector parameters of this study. In addition, gas TPCs allow an improvement in angular resolution of about one order of magnitude. High-energy astrophysics focuses on the study of com- plex objects such as active galactic nuclei (AGN), pulsars and gamma-ray bursts (GRB), the spectral energy distributions (SEDs) of which comprise contributions from a number of pro- cesses (1), including synchrotron emission, synchrotron self- Compton scattering (SSC), the inverse scattering of external thermal photons from the accretion disk (ESC), and 0 decays. These studies su er from the existence of gaps in the sensitivity of the available instruments, such as that between the Compton- scattering-based telescopes, that are mostly sensitive below 1 MeV, and the pair-based telescopes, that are mostly sensitive above 100 MeV. Pair-based telescopes also su er from a poor angular resolution at low energy, making the analysis of dense regions of the sky di cult. In this paper we present a characterization of the use of a thin detector as an active target for cosmic -ray detection in the pair-conversion regime, with the aim of improving the angular resolution and the sensitivity at low energy. The past missions and the presently operated Fermi/LAT and AGILE use thick de- tectors for which the photon conversion probability is close to unity and the e ective area A e is the product of the geomet- rical area of the detector A and of the reconstruction e ciency r: A e = A r. In a thin detector for which the conversion probability is small, the e ective area becomes proportional to the pair conversion mass attenuation coe cient H and to the detector mass M, A e = H M r. In a thick detector, the optimization of the aspect ratio height/surface is therefore criti- cal, while for a thin detector it does not a ect the e ective area to first order. Note that in a thick detector, the various pos- sible conversion processes are in competition with each other, and Compton scattering prior to- or in place of- pair conversion
9729647
Rates, polarizations, and asymmetries in charmless vector-vector B meson decays.
With a sample of approximately 89 x 10(6) B(-)B pairs collected with the BABAR detector, we perform a search for B meson decays into pairs of charmless vector mesons (phi, rho, and K*). We measure the branching fractions, determine the degree of longitudinal polarization, and search for CP violation asymmetries in the processes B+-->phiK(*+), B0-->phiK(*0), B+-->rho(0)K(*+), and B+-->rho(0)rho(+). We also set an upper limit on the branching fraction for the decay B0-->rho(0)rho(0).
140119641
Search for dimuon decays of a light scalar boson in radiative transitions Upsilon-->gammaA0.
We search for evidence of a light scalar boson in the radiative decays of the Upsilon(2S) and Upsilon(3S) resonances: Upsilon(2S,3S)-->gammaA0, A0-->mu+mu-. Such a particle appears in extensions of the standard model, where a light CP-odd Higgs boson naturally couples strongly to b quarks. We find no evidence for such processes in the mass range 0.212 < or = mA0 < or = 9.3 GeV in the samples of 99 x 10(6) Upsilon(2S) and 122 x 10(6) Upsilon(3S) decays collected by the BABAR detector at the SLAC PEP-II B factory and set stringent upper limits on the effective coupling of the b quark to the A0. We also limit the dimuon branching fraction of the etab meson: B(etab-->mu+mu-)<0.9% at 90% confidence level.
125934668
Study of CP violating asymmetries in $B \to \pi^\pm \pi^\mp$, $K^\pm \pi^\mp$ decays