43203688
Remark on charm quark fragmentation to D** mesons.
The observed [ital D][sup **] mesons have [ital c[bar q]] flavor quantum numbers and a spin-parity of the light degrees of freedom [ital s][sub [ital l]][sup [pi]][sub [ital l]]=3/2[sup +]. In the [ital m][sub [ital c]][r arrow][infinity] limit the spin of the charm quark is conserved and the [ital c][r arrow][ital D][sup **] fragmentation process is characterized by the probability for the charm quark to fragment to a [ital D][sup **] meson with a given helicity for the light degrees of freedom. We consider the calculated [ital b][r arrow][ital B][sub [ital c]][sup **] fragmentation functions in the limit [ital m][sub [ital c]]/[ital m][sub [ital b]][r arrow]0 as a qualitative model for the [ital c][r arrow][ital D][sup **] fragmentation functions. We find that in this model charm quark fragmentation to [ital s][sub [ital l]][sup [pi]][sub [ital l]]=3/2[sup +] light degrees of freedom with helicities [plus minus]1/2 is favored over fragmentation to [ital s][sub [ital l]][sup [pi]][sub [ital l]]=3/2[sup +] light degrees of freedom with helicities [plus minus]3/2.
9063079
The Physics of the B Factories
This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.
124674675
EXPERIMENTAL STUDY OF J/PSI RADIATIVE DECAY TO PI 0PI 0
119107781
QCD corrections to single slepton production at hadron colliders
We evaluate the cross section for single slepton production at hadron colliders in supersymmetric theories with R-parity violating interactions to the next-to-leading order in QCD. We obtain fully differential cross section by using the phase space slicing lethod. We also perform soft-gluon resummation to all order in alpha(s) of leading logarithm to obtain a complete transverse momentum spectrum of the slepton. We find that the full transverse momentum spectrum is peaked at a few GeV, consistent with the early results for Drell-Yan production of lepton pairs. We also consider the contribution from gluon fusion via quark-triangle loop diagrams dominated by the b-quark loop. The cross section of this process is significantly smaller than that of the tree-level process induced by the initial b (b) over bar annihilation.
120782930
On the reparameterization invariance in heavy quark effective theory
Abstract The reparameterization invariance in Heavy Quark Effective Theory is reconsidered. Starting from an effective Lagrangian derived from QCD full theory, a consistent transformation law for the heavy quark effective field under the variation of the parameter v is obtained and the reparameterization invariance in the effective Lagrangian is shown.
120909739
Relativistic corrections to heavy quark fragmentation to S-wave heavy mesons
The relativistic corrections of order v{sup 2} to the fragmentation functions for the heavy quark to S-wave heavy quarkonia are calculated in the framework of the nonrelativistic quantum chromodynamics factorization formula. We derive the fragmentation functions by using the Collins-Soper definition in both the Feynman gauge and the axial gauge. We also extract them through the process Z{sup 0}{yields}Hqq in the limit M{sub Z}/m{yields}{infinity}. We find that all results obtained by these two different methods and in different gauges are the same. We estimate the relative size of the relativistic corrections to the fragmentation functions.
18727634
Mott transition in an anyon gas.
We introduce and analyze a lattice model of anyons in a periodic potential and an external magnetic field, which exhibits a transition from a Mott insulator to a quantum Hall fluid. The transition is characterized by the anyon statistics [alpha], which can vary between fermions, [alpha]=0, and bosons, [alpha]=1. For bosons the transition is in the universality class of the classical three-dimensional [ital XY] model. Near the fermion limit, the transition is described by a massless 2+1 Dirac theory coupled to a Chern-Simons gauge field. Analytic calculations perturbative in [alpha], and also a large-[ital N] expansion, show that due to gauge fluctuations, the critical properties of the transition are dependent on the anyon statistics. Comparison with previous calculations at and near the boson limit, strongly suggest that our lattice model exhibits a fixed line of critical points, with universal critical properties that vary continuously and monotonically as one passes from fermions to bosons. Possible relevance to experiments on the transitions between plateaus in the fractional quantum Hall effect and the magnetic-field-tuned superconductor-insulator transition are briefly discussed.
22668459
Chiral-symmetry breaking in two-dimensional SU(2) QCD with fermions.
We have studied the chiral symmetry of SU(2) Yang-Mills theory coupled to an unflavored fermion on a two-dimensional lattice using a hybrid algorithm based on the projector hamiltonian Monte-Carlo method. We found chiral symmetry breaking in the continuum limit. The theory is predicted to reside in only one phase in which chiral symmetry is broken.
42992975
Study of the strong coupling constant using W+jet processes.
The ratio of the number of W + 1 jet to W + 0 jet events is measured with the D0 detector using data from, the 1992--93 Tevatron Collider run. For the W {yields} e{nu} channel with a minimum jet E{sub T} cutoff of 25 GeV, the experimental ratio is 0.065 {+-} 0.003(stat) {+-} 0.007(sys). Next-to-Leading order QCD predictions for various parton distributions agree well with each other and are all over one standard deviation below the measurement. Varying the strong coupling constant {alpha}{sub s} in both the parton distributions and the partonic cross sections simultaneously does not remove this discrepancy.
28164273
General theory of quantum statistics with internal degrees of freedom in two dimensions.
The general theory of θ statistics with internal degrees of freedom is presented. The intrinsic parts of wave functions are expressed by means of the irreducible representations of the quantum group SU(2,q) with q=e −iθ . We show that the violation of P or T reflection symmetry is involved in two kinds of coproduct for constructing these representations
43756291
Top quark search with the D0 1992-1993 data sample.
We present results on the search for the top quark in {ital p{bar p}} collisions at {radical}{ital s} =1.8 TeV with an integrated luminosity of 13.5{plus_minus}1.6 pb{sup {minus}1}. We have considered {ital t{bar t}} production in the standard model using electron and muon dilepton decay channels ({ital t{bar t}}{r_arrow}{ital e}{mu}+jets, {ital ee}+jets, and {mu}{mu}+jets) and single-lepton decay channels ({ital t{bar t}}{r_arrow}{ital e}+jets and {mu}+jets) with and without tagging of {ital b} quark jets. An analysis of these data optimized for top quark masses below 140 GeV/{ital c}{sup 2} gives a lower top quark mass limit of 128 GeV/{ital c}{sup 2}. An analysis optimized for higher top quark masses yields 9 events with an expected background of 3.8{plus_minus}0.9. If we assume that the excess is due to {ital t{bar t}} production, and assuming a top quark mass of 180 GeV/{ital c}{sup 2}, we obtain a cross section of 8.2{plus_minus}5.1 pb.