122935088
Minimal models on Riemann surfaces
Abstract We extend the Coulomb gas representation of minimal model correlation functions to higher genius Riemann surfaces. Specifically, we incorporate the “BRS” structure of this representation into the operator formalism. This allows traces over the spectrum of a minimal model to be computed from traces over Fock spaces of a free scalar field. This our results are obtained by standard sewing techniques. The formulation is general, but we present here in particular the two-loop characters of the Ising model.
13331529
Nonsymmetric gravity has unacceptable global asymptotics
We analyze the radiative aspects of nonsymmetric gravity theory to show that, in contrast to General Relativity, its nonstationary solutions cannot simultaneously exhibit acceptable asymptotic behavior at both future and past null infinity: good behavior at future null infinity is only possible through the use of advanced potentials with concomitant unphysical behavior at past null infinity.
2655982
Theoretical problems in nonsymmetric gravitational theory.
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.
120900374
Vertex operators and fusion rules in the free field realizations of WZNW models
Abstract 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.
120560048
Free Field Approach to 2-Dimensional Conformal Field Theories
11851007
Fusing the coordinates of quantum superspace
Abstract We introduce the notion of a fused quantum superplane by allowing for terms θθ ∼ x in the defining relations. We develop the differential calculus for a large class of fused quantum superplanes related to particular solutions of the Yang-Baxter equation.
17306575
First measurement of the charge asymmetry in beauty-quark pair production.
The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in bb pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(-1) collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the bb system. The results obtained are A(C)(bb))(40 105 GeV/c(2)) = 1.6 ± 1.7 ± 0.6%, where A(C)(bb)) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 < η < 4, E(T) >20 GeV, and have an opening angle in the transverse plane Δ ϕ > 2.6 rad. These measurements are consistent with the predictions of the standard model.
123077697
A New measurement of the spin dependent structure function g1(x) of the deuteron
Abstract We present a new measurement of the spin-dependent structure function g 1 d of the deuteron in deep inelastic scattering of 190 GeV polarised muons on polarised deuterons, in the kinematic range 0.003 x 2 Q 2 2 . This structure function is found to be negative at small x . The first moment Γ 1 d =∫ 0 1 g 1 d d x evaluated at Q 0 2 = 10 GeV 2 is 0.034 ± 0.009 (stat.) ± 0.006 (syst.). This value is below the Ellis-Jaffe sum rule prediction by three standard deviations. Using our earlier determination of Γ 1 p , we obtain Γ 1 p − Γ 1 n = 0.199 ± 0.038 which agrees with the Bjorken sum rule.
55565416
Luminosity lifetime in the Tevatron
Since the inauguration of colliding proton-antiproton operations in 1987, the Tevatron has exhibited luminosity lifetimes shorter than expected. During a typical colliding beam storage period, called a store, luminosity is calculated periodically by measuring the charge and emittances of each bunch. The growth of the transverse bunch emittances is the dominant cause of luminosity deterioration. Throughout, this period, the position spectrum of the bunches exhibited betatron signals larger than expected from Schottky noise. A model assuming externally driven betatron oscillations explains both the betatron signals and the emittance growth. A program is underway to improve the Tevatron luminosity lifetime. The abort kickers have been identified as sources of emittance growth, and some quadrupole power supplies are further candidates. Because the horizontal dispersion through the RF cavities is nonzero, RF phase noise has been investigated. Noise in the main dipole regulation circuit has also been studied. 13 refs., 4 figs.
109926172
Precision luminosity measurements at LHCb
Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy root s. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for root s = 2.76, 7 and 8TeV (proton-proton collisions) and for root s(NN) = 5TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at root s = 8TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determines the luminosity with a precision of 1.16%. This represents the most precise luminosity measurement achieved so far at a bunched-beam hadron collider.
17341590
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.