33607009
Direct measurement of the Ds branching fraction to phi pi.
The Beijing Spectrometer (BES) Collaboration has observed exclusive pair production of {ital D}{sub {ital s}} mesons at the Beijing Electron-Positron Collider (BEPC) at a center-of-mass energy of 4.03 GeV. The {ital D}{sub {ital s}} mesons are detected in the {phi}{pi}{sup +}, {ital {bar K}} {sup *0}{ital K}{sup +}, and {ital {bar K}} {sup 0}{ital K}{sup +} decay modes; two fully reconstructed events yield the value (3.9{sub {minus}1.9{minus}1.1}{sup +5.1+1.8})% for the {ital D}{sub {ital s}} branching fraction to {phi}{pi}. This is the first direct, model-independent measurement of this quantity.
123329692
Measurement of the B0 anti-B0 oscillation frequency in hadronic B0 decays.
B{sup 0}{bar B}{sup 0} flavor oscillations have been studied in 20.7 fb{sup -1} of e{sup +}e{sup -} annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the {Upsilon}(4S) resonance. The event sample consists of one B{sup 0} meson fully reconstructed in a hadronic decay mode, while the flavor of the recoiling B{sup 0} in the event is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. By fitting the time development of the observed mixed and unmixed final states, the B{sup 0}{bar B}{sup 0} oscillation frequency, {Delta}m{sub d}, is determined to be 0.519 {+-} 0.020 {+-} 0.016 {Dirac_h} ps{sup -1}.
125105616
Determination of the B ---> D* l nu decay width and |V(cb)|
119400985
R measurement at BES
By using the upgraded Beijing Spectrometer (BESII), the total cross section for e(+)e(-) annihilation into hadronic final states at center-of-mass energies between 2 to 5 GeV are measured. Values of R at 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV are determined, preliminary results for part of the successive points are also presented.
125934668
Study of CP violating asymmetries in $B \to \pi^\pm \pi^\mp$, $K^\pm \pi^\mp$ decays
126259018
Search for the decay $B^0 \to \gamma \gamma$
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.
2423491
Comparative study of the hadronic production of Bc mesons.
A comparative study of the full {alpha}{sup 4}{sub {ital s}} perturbative QCD calculation of the hadronic production of the {ital B}{sub {ital c}} and {ital B}{sub {ital c}}{sup {asterisk}} mesons and the fragmentation approximation is presented. We examined the various subprocesses in detail and the distribution {ital C}({ital z}), where {ital z} is twice the fraction of the {ital B}{sub {ital c}} or {ital B}{sub {ital c}}{sup {asterisk}} meson energy in the center of mass of the subprocess, which proved insightful and revealed the importance of certain nonfragmentation contributions. We concluded that the condition for the applicability of the fragmentation approximation in hadronic collisions is that the transverse momentum {ital P}{sub {ital T}} of the produced {ital B}{sub {ital c}} and {ital B}{sub {ital c}}{sup {asterisk}} be much larger than the mass of the {ital B}{sub {ital c}} meson: i.e., {ital P}{sub {ital T}}{gt}{ital M}{sub {ital B}{sub {ital c}}}. Numerical results for the cross sections at the Fermilab Tevatron are also presented using updated parton distribution functions with various kinematic cuts. {copyright} {ital 1996 The American Physical Society.}
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.
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.
46325047
Helicity decomposition for inclusive J/ psi production.
We present a general method for calculating inclusive cross sections for the production of heavy quarkonium states with definite polarization within the NRQCD factorization approach. Cross sections for polarized production can involve additional matrix elements that do not contribute to cross sections for unpolarized production. They can also include interference terms between parton processes that produce {ital Q{bar Q}} pairs with different total angular momentum. The interference terms cancel upon summing over polarizations. Our method can be generalized to {ital N} dimensions and is, therefore, compatible with the use of dimensional regularization to calculate radiative corrections. We illustrate the method by applying it to the production of {ital J}/{psi} via the parton processes {ital q{bar q}}{r_arrow}{ital c{bar c}} and {ital gg}{r_arrow}{ital c{bar c}}. {copyright} {ital 1996 The American Physical Society.}