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Theoretical studies in high energy nuclear physics. Progress report

Description: This paper is a progress report for the period 1-1-93 to 6-30-95 on a project primarily directed at the application of high energy physics techniques to nuclear structure studies, and the ability to study hadron dynamics through interactions with nuclear targets. This work has included the first legitimate QCD calculations of hard coherent diffractive processes off nucleon (nuclear) targets which established novel features of color transparency phenomenon not anticipated in the previous intuitive or QCD inspired model calculations and predicted the fast increase of the cross section for electroproduction of {rho}-mesons with increase of the energy, which was confirmed very recently by the first HERA data on this reaction. First theoretical demonstration that color transparency phenomenon for the hard diffractive processes follow from QCD in the kinematics when both x{yields}0 and Q{sup 2}{yields}{infinity}. Establishing the pattern of color (cross section) fluctuations in hadrons. Confirmed by the FNAL inelastic diffraction data. Finding that in realistic quark, skyrmion models of a hadron large momentum transfer elastic lepton-hadron scattering occurs through formation of small spatial size configurations. Discovering a novel class of color transparency sensitive double interaction processes which is complementary to quasielastic reactions originally suggested by S. Brodsky and A. Mueller. Adopting ideas suggested elsewhere for hadron initiated reactions they developed a method for taking into account nuclear correlations in (e,e{prime}p) reactions. Such an approach gives practical possibility to overcome ambiguities of optical model approximation used before and to reliably interpret color transparency effects at intermediate Q{sup 2}.
Date: August 1, 1995
Partner: UNT Libraries Government Documents Department

Review of {alpha}{sub s} measurements

Description: Determinations of {alpha}{sub s} are reviewed. Current results are limited to a precision of around 3--20%, largely by theoretical uncertainties. All measurements are consistent with a world average value of 0.118 {+-} 0.005 and there is no evidence of any discrepancy between low-Q{sup 2} and high-Q{sup 2} results. 71 refs., 1 fig., 1 tab.
Date: October 1, 1996
Creator: Burrows, P.N.
Partner: UNT Libraries Government Documents Department

Pole term and gauge invariance in deep inelastic scattering

Description: In this paper the authors reconcile two contradictory statements about deep inelastic scattering (DIS) in manifestly covariant theories: (1) the scattering must be gauge invariant, even in the deep inelastic limit, and (2) the pole term (which is not gauge invariant in a covariant theory) dominates the scattering amplitude in the deep inelastic limit. An ``intermediate'' answer is found to be true. They show that, at all energies, the gauge dependent part of the pole term cancels the gauge dependent part of the rescattering term, so that both the pole and rescattering terms can be separately redefined in a gauge invariant fashion. The resulting, redefined pole term is then shown to dominate the scattering in the deep inelastic limit. Details are worked out for a simple example in 1+1 dimensions.
Date: March 1, 1998
Creator: Batiz, Zoltan & Gross, Franz
Partner: UNT Libraries Government Documents Department

Compton scattering and nonforward parton distributions

Description: The hard exclusive electroproduction processes provide new information about hadronic structure accumulated in nonforward parton distributions. The NFPD's are universal hybrid functions having the properties of parton densities, hadronic form factors and distribution amplitudes. They give a unified description of various hard exclusive and inclusive reactions. The basic supplier of information about nonforward parton distributions is deeply virtual Compton scattering which offers a remarkable example of Bjorken scaling phenomena in exclusive processes. Wide-angle real Compton scattering is an ideal tool to test angle-dependent scaling laws characteristic for soft overlap mechanism. Hard meson electroproduction is the best candidate to see pQCD hard gluon exchange in exclusive reactions.
Date: November 1, 1998
Creator: Radyushkin, A.V.
Partner: UNT Libraries Government Documents Department

The parton distribution functions in the limit x{sub BJ} {yields} 1

Description: We review both the counting rule and the influence of the evolution in Q{sub 2} for the large {chi}{sub Bj} behavior of the valance quark distribution functions. Based on a factorization procedure we present a more general perturbative treatment to compute this behavior. A complete analysis is performed in the scalar {phi}{sub [6]}{sup 3}-theory for the parton distribution function of the ``meson,`` which shows that logarithmical corrections arise from the distribution amplitude and that the reference momentum square Q{sub 0}{sup 2} is fixed by {chi}{sub Bj}.
Date: May 1, 1994
Creator: Mueller, D.
Partner: UNT Libraries Government Documents Department

Consequences of unitarity and analyticity for weak interactions

Description: One considers the implications of the fact that weak two body scattering amplitudes, when calculated to all orders in any renormalizable model, should exhibit unitary, analytic, ''Mandelstam'' behavior. One discusses from this point of view, the existence of neutral currents, the suppression of $nu$/sub $mu$/e elastic scattering, and the possibility of lepton hadron resonances. A brief review is given of the predictions for lepton--lepton scattering of two models in which Mandelstam behavior is explicitly realized. (auth)
Date: January 1975
Creator: Dicus, D. A. & Teplitz, V. L.
Partner: UNT Libraries Government Documents Department

Same-Sign Dilepton Production by Neutrinos

Description: There has been considerable experimental work on same-sign dilepton production in neutrino interactions over the past 10 years. However, the situation is still unclear. Most experiments do have evidence for an excess of candidates but there is a lack of independent statistically significant results. Present experiments at the Tevatron may provide important new information. However the recent revision of older results and the lower rates from recent experiments indicate that real progress will be difficult. Furthermore, the problems encountered with ..pi../K background subtractions argue for a multi-target experiment. Also, given the conflict with present c anti c calculations, a high statistics bubble chamber experiment would be useful to establish the presence/absence of c anti c events at the presently measured production rates. 13 refs., 6 figs., 2 tabs.
Date: November 7, 1985
Creator: Murtagh, Michael J.
Partner: UNT Libraries Government Documents Department

Theoretical Aspects of Lepton-Hadron Scattering

Description: In this paper, I will emphasize two points on Theoretical Aspects of Lepton-Hadron Scattering: (1) The crucial importance of testing the ``exact`` sum rules as tests of the local current algebra. Discrepancies, if found, between experiment and theory cannot be ``interpreted away`` in terms of more complex parton wave functions for the hadronic ground state. The three sum rules of interest are those of Adler, Bjorken, and Gross and Llewellyn-Smith. (2) An understanding of the corrections to scaling in QCD and what they teach us.
Date: January 1992
Creator: Drell, Sidney D.
Partner: UNT Libraries Government Documents Department

Progress report of a research program in experimental and theoretical high energy physics, 1 January 1992--31 May 1992

Description: This report discusses research at Brown University in experimental and theoretical high energy physics. Some of the research programs conducted are: interactions of leptons and hadrons form accelerator and astrophysical sources; hadron interactions with hydrogen and heavier nuclei; large volume detector at the Gran Sasso Laboratory; GEM collaboration at SSC; and hadron colliders and neutrino physics. (LSP)
Date: June 1, 1992
Creator: Brandenberger, R.; Cutts, D.; Fried, H. M.; Guralnik, G.; Jevicki, A.; King, K. et al.
Partner: UNT Libraries Government Documents Department

Data acquisition for FNAL E665

Description: The data acquisition system for FNAL E665, an experiment to study deep inelastic muon scattering from nucleons and nuclei, is described. The system is built with the FNAL VAXONLINE and RSX DA building blocks. The structure, capabilities and limitations for data flow, control and monitoring are discussed. 20 refs., 1 fig.
Date: January 1, 1989
Creator: Geesaman, D.F.; Green, M.C.; Kaufman, S.; Tentindo-Repond, S.; Bartlett, J.F.; Melanson, H.L. et al.
Partner: UNT Libraries Government Documents Department

On defining the un-definable: JETS

Description: A brief summary is presented of the current status of jet studies in hadron-hadron collisions. The primary focus is on those issues that would benefit from comparisons of jet samples obtained from hadron-hadron collisions, from e{sup +}e{sup {minus}} annihilation events at LEP and from deep inelastic collisions at HERA. The important point is that, to perform this comparison properly, the jet various samples must be obtained using the same jet definition.
Date: January 1, 1990
Creator: Ellis, S.D.
Partner: UNT Libraries Government Documents Department

Determination of sin/sup 2/THETA/sub w/ and rho in deep inelastic neutrino-nucleon scattering

Description: We have determined the electroweak parameters sin/sup 2/THETA/sub w/ and rho by a measurement of deep inelastic neutrino-nucleon scattering using a fine grained neutrino detector exposed to a narrow band neutrino beam at Fermilab. The unique sampling properties of our detector have permitted neutral current and charged current events to be unambiguously identified over a wide kinematic range, thereby allowing a determination of sin/sup 2/THETA/sub w/ and rho to be made with good statistics and small systematic errors. We have found sin/sup 2/THETA/sub w/ = 0.246 +- 0.012 +- 0.013 in a single parameter fit. The details of the experimental and theoretical systematic errors are given. 17 refs., 2 figs., 2 tabs.
Date: June 1, 1985
Creator: Bogert, D.; Burnstein, R.; Fisk, R.; Fuess, S.; Morfin, J.; Ohska, T. et al.
Partner: UNT Libraries Government Documents Department

Impact of the e-p option on Isabelle experimental areas

Description: There have been many suggestions for the expansion of existing or planned storage rings to include high energy e-p collisions. We will not discuss the physics potential here, but there is a general concensus that a facility with protons colliding with electrons and positrons of selectible helicity would provide great insight into weak interactions, nucleon structure, etc., in a way not duplicated at e/sup +/e/sup -/, pp, nor anti pp machines. In this report, some aspects of the addition of a 10 to 20 GeV electron ring to Isabelle are discussed.
Date: January 1, 1981
Creator: Foley, K.J.; Kantardjian, G.; Lanou, R.; Paar, H. & Stevens, A.
Partner: UNT Libraries Government Documents Department

Impact of the e-p option on ISABELLE experimental areas

Description: There have been many suggestions for the expansion of existing or planned storage rings to include high energy e-p collisions. There is a general concensus that a facility with protons colliding with electrons and positrons of selectible helicity would provide great insight into weak interactions, nucleon structure, etc., in a way not duplicated at e/sup +/e/sup -/, pp nor anti pp machines. Some aspects of the addition of a 10 to 20 GeV electron ring to Isabelle are discussed.
Date: January 1, 1981
Creator: Foley, K.J.; Kantardjian, G.; Lanou, R.; Paar, H & Stevens, A.
Partner: UNT Libraries Government Documents Department

Twist-four effects in deep inelastic neutrino scattering and sinStheta/sub w/

Description: In addition to the standard perturbative QCD corrections to deep inelastic scattering, there are nonperturbative twist-four corrections which behave like 1/QS relative to the lnQS leading log corrections. We have calculated the twist-four, spin-one and spin-two corrections to sigma/sub NC/, sigma/sub CC/, R/sub nu/ and R/sub anti nu/ using the following procedure: The bilocal product of the weak currents is expanded into local operators using the Wilson operator product expansion. The coefficient functions obey the renormalization group equations and, neglecting the anomalous dimensions of the operators, were calculated using perturbative techniques. The nucleon matrix elements of the local operators can then be evaluated assuming some quark confinement model. We found that twist-four, spin-two corrections to the neutral current neutrino scattering decreases sinStheta/sub w/ by about 1%. Taking into account the twist-four, spin-two corrections for the charged current cross section, we found that they give a dominant contribution to the ratio R/sub nu/ and increased sinStheta/sub w/ by about 0.5%. We also have studied the model dependence of our results, and we have found that the twist-four, spin-two corrections to sinStheta/sub w/ are quite model dependent. The twist-four, spin-one corrections to the neutrino scattering were also calculated. These corrections come from two-quark, one-gluon operators and even at low QS their contribution was found to be considerably smaller than the twist-four, spin-two corrections.
Date: July 1, 1985
Creator: Fajfer, S. & Oakes, R.J.
Partner: UNT Libraries Government Documents Department

Azimuthal energy flow in deep inelastic neutrino scattering

Description: Gluon emission and the transverse momentum (p/sub t/) of partons confined in nucleons were studied using deep-inelastic charged-current neutrino-nucleon interactions. For this analysis we use the flow of hadronic energy in the azimuthal direction around the momentum transfer referenced from the neutrino-muon scattering plane. A five standard deviation asymmetry was found. Analysis of this asymmetry indicates a (p/sub t/) of 0.35 +- 0.12 GeV/c if QCD corrections are included, and 0.56 +- 0.05 GeV/c if they are excluded. Some evidence was also observed for x dependence in p/sub t/. Data were taken at Fermilab in 1982 using a 200 ton (fiducial mass) fine grained calorimeter and a dichromatic neutrino beam.
Date: June 12, 1986
Creator: Mukherjee, A.; Bofill, J.; Busza, W.; Eldridge, T.F.; Friedman, J.I.; Fuess, S. et al.
Partner: UNT Libraries Government Documents Department

Heavy quark production in ep collisions at HERA. [None]

Description: There are substantial production rates of heavy quarks from ep collisions at HERA. The center of mass energy of about 300 GeV is well above any b-quark threshold effects, and for b/bar b/ production, the cross section is estimated to be 3.3 nb per event, leading to rates approaching 10/sup 6/ b mesons per year. The rates for c/bar c/ production are about two orders of magnitude greater. Two major detectors are under construction and a program of heavy quark physics will start in 1990. 3 refs., 4 figs.
Date: December 22, 1987
Creator: Derrick, M.
Partner: UNT Libraries Government Documents Department