Determination of the angular and energy dependence of hard constituent scattering from π0 pair events at the CERN intersecting storage rings

A. L.S. Angelis, H. J. Besch, B. J. Blumenfeld, L. Camilleri, T. J. Chapin, R. L. Cool, C. del Papa, L. Di Lella, Z. Dimčovski, R. J. Hollebeek, L. M. Lederman, D. A. Levinthal, J. T. Linnemann, C. B. Newman, N. Phinney, B. G. Pope, S. H. Pordes, A. F. Rothenberg, R. W. Rusack, A. M. SegarJ. Singh-Sidhu, A. M. Smith, M. J. Tannenbaum, R. A. Vidal, J. S. Wallace-Hadrill, J. M. Yelton, K. K. Young

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

We present data on proton-proton collisions, obtained at the CERN Intersecting Storage Rings, in which two roughly back-to-back π0's of high transverse momentum (pT) were produced. The angular distribution of the dipion axis relative to the collision axis is found to be independent of both the effective mass m of the dipion system and the centre-of-mass energy √s of the proton-proton collision. The cross-sections dσ dm at the values of √s satisfy a scaling law of the form dσ dm = G(x) mn, where x = m(π0, π0)//trs and n = 6.5 ± 0.5. We show from our data that the leading π0 carries most of the momentum of the scattered parton. Given this fact, the axis of the dipion system follows closely the direction of the scattered constituents, and we exploit this to determine the angular dependence of the hard-scattering subprocess. We also compare our data with the lowest order QCD predictions using structure functions as determined in deep-inelastic scattering and fragmentation functions from electron-positron annihilation.

Original languageEnglish (US)
Pages (from-to)284-300
Number of pages17
JournalNuclear Physics, Section B
Volume209
Issue number2
DOIs
StatePublished - Dec 27 1982

Bibliographical note

Funding Information:
We present data on proton-proton colhslons, obtained at the CERN Intersecting Storage Pangs, m which two roughly back-to-back ¢r° 's of high transverse momentum (P-r) were produced The angular distribution of the d:plon axis relative to the colhslon axis is found to be independent of both the effective mass m of the d~plon system and the centre-of-mass energy ~/s of the proton-proton colhslon The cross-sections do/dm at the two values of ~/s satisfy a scaling law of the form do/din = G(x)/m", where x = m(~r °, ~r°)/~/s and n = 6 5 _+ 0 5 We show from our data that the leading ~r° carries most of the momentum of the scattered parton Given th~s fact, the axis of the dlpion system follows closely the &rectlon of the scattered conshtuents, and we exploit this to determine the angular dependence of the hard-scattering subprocess We also compare our data with the lowest order QCD pre&ctlons using structure funchons as determined in deep-inelastic scattering and fragmentation functions from electron-positron anmhllahon * Present address Physics Dept, Johns Hopkins Umverslty, Bait:more, Md, USA ** Present address INFN, Sezione dl Bologna, Italy *** Present address Umverslty of Skopje, Macedonia. Yugoslavia t Present address. SLAC, Stanford, Calaf, USA *t Present address Fermdab, Batavia, Ill, USA t*t Present address Physics Dept. Pnnceton Umverslty, Princeton, N J, USA + Present address Physics Dept, Umverslty of Manchester, UK + + Present address Brookhaven National Laboratory, Upton, NY, USA +++ Permanent address Physxcs Dept, University of Washington, Seattle, Wash, USA × Research supported m part by the National Science Foundation × × Research supported m part by the US Department of Energy ××× Present address Rockefeller Umverslty, New York, NY, USA

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