12688599
Anomalous dimension of the gluon operator in pure Yang-Mills theory.
We present new one loop calculations that confirm the theorems of Joglekar and Lee on the renormalization of composite operators. We do this by considering physical matrix elements with the operators inserted at [ital nonzero] momentum. The resulting IR singularities are regulated dimensionally. We show that the physical matrix element of the BRST exact gauge-variant operator which appears in the energy-momentum tensor is zero. We then show that the physical matrix elements of the classical energy-momentum tensor and the gauge-invariant twist-two gluon operator are independent of the gauge-fixing parameter. A Sudakov factor appears in the latter cases. The universality of this factor and the UV finiteness of the energy-momentum tensor provide another method of finding the anomalous dimension of the gluon operator. We conjecture that this method applies to higher loops and takes full advantage of the triangularity of the mixing matrix.
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.
123858028
Radiative corrections to the invariant-mass spectrum of a dalitz pair
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.
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.
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
35600922
Measurement of the branching fraction for D+-->K- pi + pi +
Using the CLEO-II detector at CESR we have measured the ratio of branching fractions, B(D+ → K−π+π+)/B(D0 → K−π+) = 2.35 ± 0.16 ± 0.16. Our recent measurement of B(D0 → K−π+) then gives B(D+ → K−π+π+) =
42871335
Search for exclusive b-->u semileptonic decays of B mesons.
Using a sample of 935000 BB pairs collected with the CLEO-II detector at the Cornell Storage Ring, we have obtained upper limits on the branching ratios for the b→ul - υ#58 processes B - →ωl - υ#58, B - →ρ 0 l - υ#58, and B 0 →ρ + l - υ#58. The combined result using the relationships among the widths for these three modes is B(B - →ρ 0 l - υ#58)<(1.6-2.7)×10 -4 at 90% C. L., where the range of value to model dependence of the detection efficiencies. These measurements yield the limits |V ub /V cb |<0.08-0.13
36064182
Tau decays with one charged particle plus multiple pi 0's.
With the CLEO-II detector at the Cornell Electron Storage Ring, we have measured branching fractions for tau lepton decay into one-prong final states with multiple [pi][sup 0]'s [ital B][sub [ital h][ital n][pi]][sup 0], normalized to the branching fraction for tau decay into one charged particle and a single [pi][sup 0]. We find [ital B][sub [ital h]2[pi]][sup 0]/[ital B][sub [ital h][pi]][sup 0]=0.345[plus minus]0.006[plus minus]0.016, [ital B][sub [ital h]3[pi]][sup 0]/[ital B][sub [ital h][pi]][sup 0]=0.041 [plus minus]0.003[plus minus]0.005, and [ital B][sub [ital h]4[pi]][sup 0]/[ital B][sub [ital h][pi]][sup 0]=0.006[plus minus]0.002[plus minus]0.002.
6390938
Inclusive chi (2P) production in Upsilon (3S) decay.
Using the CsI calorimeter of the CLEO II detector, the spin triplet {chi}{sub {ital b}}(2{ital P}) states are observed in {Upsilon}(3{ital S}) radiative decays with much higher statistics than seen in previous experiments. The observed mass splittings are not described well by theoretical models, while the relative branching ratios agree with predictions that include relativistic corrections to the radiative transition rates.
38939426
Observation of inclusive B decays to the charmed baryons Sigma c++ and Sigma c0.
Using data collected in the region of the [Upsilon](4[ital S]) resonance with the CLEO II detector operating at the Cornell Electron Storage Ring, we report on evidence for the production of [Sigma][sub [ital c]][sup ++] and [Sigma][sub [ital e]][sup 0] baryons in [ital B] decays, with [Sigma][sub [ital c]][r arrow][Lambda][sub [ital c]][sup +][pi]. This observation is based on 77[plus minus]19[Sigma][sub [ital c]][sup ++] and 76[plus minus]21[Sigma][sub [ital c]][sup 0] candidates from [ital B] decays. We find the product branching fractions [ital scrB]([ital [bar B]][r arrow][Sigma][sub [ital c]][ital X])[ital scrB]([Lambda][sub [ital c]][sup +][r arrow][ital pK][sup [minus]][pi][sup +]) for [Sigma][sub [ital c]]=[Sigma][sub [ital c]][sup ++], [Sigma][sub [ital c]][sup 0], and [Sigma][sub [ital c]][sup +] to be (2.1[plus minus]0.8[plus minus]0.7)[times]10[sup [minus]4], (2.3[plus minus]0.8[plus minus]0.7)[times]10[sup [minus]4], and less than 4.8[times]10[sup [minus]4] at 90% confidence level, respectively. A study of the [Sigma][sub [ital c]][sup ++] and [Sigma][sub [ital c]][sup 0] momentum spectra indicates that [ital B] decays to two-body final states with [Sigma][sub [ital c]] are suppressed.