122638824
QCD Corrections to Heavy Quark Production in p anti-p Collisions
We investigate QCD corrections to the cross section and differential distributions for $p+\overline{p}\ensuremath{\rightarrow}Q+\overline{Q}+X$, where $Q$ and $\overline{Q}$ are heavy quarks. We calculate the order-${\ensuremath{\alpha}}_{s}$ corrections to the parton reaction $g+g\ensuremath{\rightarrow}Q+\overline{Q}$. At the quark level this involves the computation of the virtualgluon contributions to the reactions $g+g\ensuremath{\rightarrow}Q+\overline{Q}$, and the soft and hard contributions from the reaction $g+g\ensuremath{\rightarrow}Q+\overline{Q}+g$. Results are given for the cross section and differential distributions for the range of $p\overline{p}$ collision energies available at CERN and Fermilab. A comparison is made with the recent data from the UA1 Collaboration.
18918927
Two loop operator matrix elements calculated up to finite terms for polarized deep inelastic lepton - hadron scattering
We present the two-loop corrected operator matrix elements contributing to the scale evolution of the longitudinal spin structure function $g_1(x,Q^2)$ calculated up to finite terms which survive in the limit $\epsilon = N - 4 \to 0$. These terms are needed to renormalize the local operators up to third order in the strong coupling constant $\alpha_s$. Further the expressions for the two-loop corrected operator matrix elements can be inserted into one loop graphs to obtain a part of the third order contributions to these matrix elements. This work is a first step in obtaining the third order anomalous dimensions so that a complete next-to-next-to-leading order (NNLO) analysis of the above mentioned structure function can be carried out. In our calculation particular attention is paid to the renormalization constant which is needed to restore the Ward-identities violated by the HVBM prescription for the $\gamma_5$-matrix in $N$-dimensional regularization.
123015361
Electromagnetic production of trimuons in muon scattering: Bethe-Heitler reactions with muon and heavy-lepton pairs
We analyze the Bethe-Heitler production of muon and heavy-lepton pairs using high-energy muon beams on a variety of targets. We give results for coherent production from a nucleus, for incoherent production from individual protons and neutrons, and for deep-inelastic production. Differential distributions are presented for the final leptons and the effects of experimental cuts are considered. This work complements our previous study of trimuon production via muon radiation, Compton radiation, and hadronic final-state interactions.
2742768
The Heavy-Flavour Contribution to Proton Structure
We present theoretical and experimental considerations pertaining to deeply inelastic heavyflavour production at HERA. The various theoretical uncertainties in the cross section calculation are discussed. Cuts are imposed to determine the fraction of charm production accessible to the detectors. The production of charm at asymptotic Q 2 and bottom production are also covered. Experimental aspects include current charm production data analysis and prospects for future analyses including anticipated high precision and distinguishing photon-gluon fusion charm events from excitation from the charm parton density. The feasibility of measuring
120632854
Evaluation of a test for the tau neutrino in the zero-muon channel
Abstract Extending previous work, we assess the feasibility of using the visible energy distribution for zero-muon events in a beam dump experiment as a possible means of observing the tau neutrino. The method would require an extremely precise knowledge of various neutrino fluxes and corresponding background reactions, and hence is not as reliable as the muon-trigger test proposed earlier.
123858028
Radiative corrections to the invariant-mass spectrum of a dalitz pair
16011903
First observation of five charmless hadronic B decays
There has been much progress in measurements of charmless hadronic B decays during 1997. Building on the previous indications from CLEO and LEP, CLEO now has clear signals in five exclusive final states: K^+\pi^, K^0\pi^+, etapr K^+, etapr K^0, and omega K^+. The branching fractions for the etapr K modes are several times larger than the others. A similar strikingly large signal has been seen in the inclusive decay, B->etapr X_S. All of these signals would appear to be dominated by hadronic penguin processes. (Invited talk presented at the Seventh International Symposium On Heavy Flavor Physics, Santa Barbara, CA, July 7-11, 1997.)
118854850
Polarized quark distributions in nuclear matter
We compute the polarized quark distribution function of a bound nucleon. The chiral quark-soliton model provides the quark and antiquark substructure of the nucleon embedded in nuclear matter. Nuclear effects cause significant modifications to the polarized distributions, including an enhancement of the axial coupling constant.
121273996
A study of double tagged two-photon reactions at spear☆
Abstract We have identified 262 doubly tagged two-photon events. A subset of the data shows an enhancement of 21 events in the inclusive two-photon mass squared distribution between 0.8 and 2.2 GeV 2 . If these events result from spin 2 resonance production then Γ γγ = 9.5 ± 3.9 ± 2.4 keV (statistical and systematic). From another subset of 58 events in which the final state could be classified we determine the two-photon hadron to muon cross section ratio R γγ = 1.1 ± 0.3 ± 0.3.
16140569
Determination of the phase of V(ub) from charmless hadronic B decay rates
We perform a model dependent fit to recent data on charmless hadronic B decays and determine $\gamma$, the phase of $V^*_{ub}$. We find $\gamma = 114^{+25}_{-21}$ degrees, which disfavors the often quoted $\gamma \sim 60^\circ$ at the two standard deviation level. We also fit for the form factors $F_0^{B\pi}$ and $A_0^{B\rho}$, and the strange-quark mass. They are consistent with theoretical expectations, although $m_s$ is somewhat low. Such agreement and the good $\chi^2$ for the fit may be interpreted as a confirmation of the adequacy of our model assumptions.
119443667
Return of the EMC effect: Finite nuclei
A light front formalism for deep inelastic lepton scattering from finite nuclei is developed. In particular, the nucleon plus momentum distribution and a finite system analog of the Hugenholtz-van Hove theorem are presented. Using a relativistic mean field model, numerical results for the plus momentum distribution and ratio of bound to free nucleon structure functions for Oxygen, Calcium and Lead are given. We show that we can incorporate light front physics with excellent accuracy while using easily computed equal time wavefunctions. Assuming nucleon structure is not modified in-medium we find that the calculations are not consistent with the binding effect apparent in the data not only in the magnitude of the effect, but in the dependence on the number of nucleons.