Measurement of the double-spin asymmetry ALL for inclusive multi-γ pair production with 200 GeV/c polarized proton beam and polarized proton target

D. L. Adams, N. Akchurin, N. I. Belikov, A. Bravar, J. Bystricky, P. Chaumette, M. D. Corcoran, J. D. Cossairt, J. Cranshaw, J. Deregel, A. A. Derevschikov, G. Durand, H. En'yo, J. Fabre, K. Fukuda, H. Funahashi, Y. Goto, O. A. Grachov, D. P. Grosnick, D. A. HillT. Iijima, K. Imai, Y. Itow, K. Iwatani, T. Kasprzyk, K. W. Krueger, K. Kuroda, M. Laghai, F. Lehar, A. de Lesquen, D. Lopiano, F. C. Luehring, T. Maki, S. Makino, A. Masaike, Yu A. Matulenko, A. P. Meschanin, A. Michalowicz, D. H. Miller, K. Miyake, T. Nagamine, F. Nessi-Tedaldi, M. Nessi, C. Nguyen, S. B. Nurushev, Y. Ohashi, Y. Onel, D. I. Patalakha, G. Pauletta, A. Penzo, A. L. Read, J. B. Roberts, L. van Rossum, V. L. Rykov, N. Saito, G. Salvato, P. Schiavon, J. Shepard, J. Skeens, V. L. Solovyanov, H. Spinka, R. Takashima, F. Takeutchi, N. Tamura, N. Tanaka, D. G. Underwood, A. N. Vasiliev, A. Villari, J. L. White, S. Yamashita, A. Yokosawa, T. Yoshida, A. Zanetti

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Abstract

The invariant double-differential cross section, E1E2d6σ / dp31dp32, and the double-spin asymmetry, A LL, for inclusive multi-γ pair production in which γ-rays came from neutral mesons were measured with a 200 GeV/c longitudinally-polarized proton beam and a longitudinally-polarized proton target. Most of the multi-γ pairs comes from two-jet type events which are sensitive to partonic interaction. The ALL values were found to be consistent with zero. The invariant double-differential cross section for inclusive π0π0 production was also measured. These measured cross sections are consistent with LUND Monte Carlo simulations. Using the LUND Monte Carlo simulation package with the Carlitz-Kaur model of spin dependent distribution functions of valence quarks, the ALL values have been compared with theoretical predictions of gluon polarization, ΔG/G. The results put restrictions on the size of ΔG/G in the region of 0.05 {less-than or approximate} x {less-than or approximate} 0.35.

Original languageEnglish
Pages (from-to)269-274
Number of pages6
JournalPhysics Letters B
Volume336
Issue number2
DOIs
StatePublished - Sep 22 1994

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