10101389
Symplectic structure of Yang-Mills theory in BRST formalism.
We construct a symplectic form for classical Yang-Mills theory, which is manifestly covariant and Becchi-Rouet-Stora-Tyutin invariant. This suggests an approach to eliminate the degeneracy that exists in the initially given two-form for the theory.
119850463
Charged Pion Photoproduction
We extracted the differential cross section for the γn→π−p process from a deuterium target using the CLAS detector at Jefferson Lab in Hall B for photon energies between 1.0 and 3.5 GeV and pion center‐of‐mass (c.m.) angles (θc.m.) between 50° and 115°. We confirm a previous indication of a broad enhancement around a c.m. energy (s) of 2.1 GeV at θc.m. = 90° in the scaled differential cross section, s7dσdt and a rapid fall‐off in a center‐of‐mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of this enhancement as the suggested scaling region is approached for θc.m. from 70° to 105°.
119207670
PHASE-RESOLVED SPECTRAL ANALYSIS OF 4U 1901+03 DURING ITS OUTBURST
The high-mass X-ray binary 4U 1901+03 is reported to have a pulse profile evolving with the X-ray luminosity and energy during its outburst in 2003 February-July: the pulse peak changed from double to single along with the decreasing luminosity. We have carried out a detailed analysis on the contemporary phase-resolved energy spectrum of 4U 1901+03 as observed by the Rossi X-ray Timing Explorer. We find that the spectra are phase dependent. At the beginning of the outburst, the maximum of the optical depth for Compton scattering is near the major phase peak. During the decay of the outburst, the optical depth has the maximum away from the main peak of the pulse profile. For each observation, Fe Kα emission line is detected in the phase-resolved spectra, and its flux is constant across the pulse phases. This suggests that the origin of the Fe emission is from the accretion disk, not the surface of the neutron star.
44727684
BRST quantization of topological field theory.
The canonical quantization of the topological field-theory model {Sigma}, proposed by Horowitz, is examined through the Becchi-Rouet-Stora-Tyutin approach. With this approach we have a manifestly covariant description of a certain class of topological quantum field theories. However, if {ital M} in the present model is any orientable four-dimensional manifold, one would end up with different theories when different polarizations are chosen. Therefore a restriction {ital M}={ital R}{sup 1}{times}{Sigma}, as pointed out by Horowitz, is required for consistency.
16855657
Critical statistical charge for anyonic superconductivity.
We examine a criterion for the anyonic superconductivity at zero temperature in Abelian matter-coupled Chern-Simons gauge-field theories in three dimensions. By solving the Dyson-Schwinger equations, we obtain a critical value of the statistical charge for the superconducting phase in a massless fermion-Chern-Simons model. {copyright} {ital 1996 The American Physical Society.}
28535306
Implications of a cosmological constant varying as R-2.
We advocate the possibility that the (effective) cosmological constant {Lambda} varies in time as {ital R}{sup {minus}2}, {ital R} being the scale factor of our expanding Universe. This behavior can be obtained under some simple and general assumptions in conformity with quantum cosmology. After pointing out several advantages worth noticing, we show that such a time-varying {Lambda} leads to no conflict with existing observations. However, it does change the predictions of the standard cosmology in the matter-dominated epoch and alleviates some problems in reconciling observations with the inflationary scenario. In particular, this medium'' time variation of {Lambda} leads to creation of matter with a rate at present which is comparable to that in the steady-state cosmology.
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.
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.
125927421
Measurement of the mass of the tau lepton.
Author(s): Bai, JZ; Bardon, O; Becker-Szendy, RA; Blum, I; Breakstone, A; Burnett, T; Chen, GP; Chen, HF | Abstract: A data-driven energy scan in the immediate vicinity of the τ pair production threshold has been performed using the Beijing Spectrometer at the Beijing Electron-Positron Collider. Approximately 5pb-1of data, distributed over 12 scan points, have been collected. A previous mass value for the τ lepton, obtained using only the eµ final state, has been published. In this paper, the final BES result on the mass measurement is presented. The analysis is based on the combined data from the ee, eµ, eh, µµ, µh, and hh final states, where h denotes a charged Π or K. A maximum likelihood fit to the τ pair production cross section data yields the value mT=1776.96-0.21-0.17+0.18+0.25. © 1995 The American Physical Society.
40500552
Measurement of the bottom-quark production cross section in 800 GeV/c proton-gold collisions.
Using a silicon-microstrip detector array to identify secondary vertices, we have observed {ital b}{r_arrow}{ital J}/{psi}{r_arrow}{mu}{sup +}{mu}{sup {minus}} decays in 800 GeV/{ital c} proton-gold interactions. The doubly differential cross section for {ital J}/{psi} mesons originating from {ital b}-quark decays, assuming linear dependence on nucleon number, is {ital d}{sup 2}{sigma}/{ital dx}{sub {ital Fdp}}{sup 2}{sub {ital T}}=107{plus_minus}28{plus_minus}19/nucleon at {ital x}{sub {ital F}}=0.05 and {ital p}{sub {ital T}}=1GeV/{ital c}. This measurement is compared to next-to-leading-order QCD predictions. The integrated {ital b}-quark production cross section, obtained by extrapolation over all {ital x}{sub {ital F}} and {ital p}{sub {ital T}}, is {sigma}({ital pN}{r_arrow}{ital bb}{ovr bar}+{ital X})=5.7{plus_minus}1.5{plus_minus}1.3 nb/nucleon.
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