3003646
Heavy quark production in deep-inelastic scattering at HERA.
We discuss two topics in the production of heavy quarks in deep-inelastic scattering: the next-to-leading order Monte-Carlo HVQDIS and the next-to-leading logarithmic resummation of soft gluon effects, including estimates of next-to-next-to-leading order corrections therefrom.
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.
119810153
Comparison of trimuon production mechanisms
We compare the predictions of six models for neutrino (and antineutrino) production of trimuon events. In particular, results are given for models based on heavy-charged-lepton decays, heavy-neutral- lepton decays together with heavy-quark decays, diffractive production and decay of heavy-quark pairs, heavy-quark cascade decays, the decays of Higgs mesons, and the radiative production of muon pairs. Our comparison should help to unravel the sources of the trimuon events detected at Fermilab and CERN. We also examine the probability of explaining the so-called superevents in which the muons are extremely energetic.
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.
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.
123858028
Radiative corrections to the invariant-mass spectrum of a dalitz pair
120150178
Measurement of anomalous muon pair production in electron-positron annihilations
We have observed 16 events of the type ..mu../sup +/..mu../sup -/ + (missing energy and momentum) from e/sup +/e/sup -/ annihilations at center-of-mass energies between 6.4 and 7.4 GeV. Taking into account QED backgrounds, we find an excess of 11 anomalous dimuon events. If these are attributed to the production and subsequent decay of a pair of heavy leptons L/sup + -/, we obtain the muonic braching ratio B ((L/sup +/ ..-->.. ..mu../sup +/..nu../sub ..mu../nu-bar/sub L/)/ (L/sup +/ ..-->.. all)) = 0.22/sup +0.07//sub -0.08/.
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.)
119482861
Chiral solitons in nuclei: Electromagnetic form factors
We calculate the electromagnetic form factors of a bound proton. The chiral quark-soliton model provides the quark and antiquark substructure of the proton, which is embedded in nuclear matter. This procedure yields significant modifications of the form factors in the nuclear environment. The sea quarks are almost completely unaffected, and serve to mitigate the valence quark effect. In particular, the ratio of the isoscalar electric to the isovector magnetic form factor decreases by 20% at Q{sup 2}=1 GeV{sup 2} at nuclear density, and we do not see a strong enhancement of the magnetic moment.
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.
94362727
Studies of radiation damage to CAMEX64 preamplifiers exposed to gamma -rays at the Cornell High Energy Synchrotron Source
CAMEX64 preamplifiers, developed for use in the readout of silicon strip detectors, have been exposed to well-measured doses of monochromatic gamma -rays from the Cornell High Energy Synchrotron Source (CHESS), and measurements of the resulting radiation damage have been made. Silicon strip detectors with their associated CAMEXes will be installed close to the interaction region in the CLEO experiment at Cornell University, where they will be exposed to both charged particle and photon fluences. Powered and unpowered CAMEXes were irradiated and after each exposure measurements of pedestals, gains, and coherent and incoherent noise were made until the devices could no longer be read out. Results are presented for noise and gain degradation as a function of dose. Using well-controlled and calibrated 20 keV synchrotron radiation, failure begins at 20 krad in powered CAMEXes and between 60 and 120 krad in unpowered CAMEXes. These failure levels are considerably larger than the projected radiation dose.<<ETX>>