A Study of the Inclusive Reaction γp → π^– + (Anything) with Polarized Photons at 2.8, 4.7, and 9.3 GeV

Technical Report · Wed Dec 01 04:00:00 EST 1971

DOI:https://doi.org/10.2172/1441436· OSTI ID:1441436

Moffeit, K. C. ^[1]

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1. Stanford University, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)

We study the inclusive spectra of π^- mesons from the events obtained in three exposures of the SLAC 82” HBC to a nearly monochromatic polarized photon beam of mean energies 2.8, 4.7, and 9.3 GeV. The data are presented in terms of transverse momentum p_⟂ and three suggested choices for the other independent variable, i. e., the longitudinal momentum p_∥ in the laboratory system, the rapidity variable y = 1/2 ln [(E+ p_∥)/(E - p_∥)], and the variable suggested by Feynman x = p$$^{*}_{∥}$$/p$$^{*}_{max}$$ in the c .m. s. The 4π geometry of the bubble chamber allows us to cover the entire kinematically allowed range of these variables. We show that exact limiting fragmentation does not occur at our energies, but the data are compatible with an approach to a limiting distribution as A + Bs^-1/2. The qualitative features of the structure function f(x, p$$^{2}_{⟂}$$) in terms of Feynman’s x-variable are similar at the three energies. Quantitatively, we find 5-10% differences between the 4.7 and 9.3 GeV data near x=0. We find f(x, p$$^{2}_{⟂}$$) is not factorizable into independent functions of x and p$$^{2}_{⟂}$$. For our data the mean π¯ multiplicity is described well by < n^–> = c^– ln s + d^–, where c^– = 0.44 % 0.04 and d^– =0.07 ± 0.08.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: US Atomic Energy Commission (AEC)
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 1441436
• Report Number(s): SLAC-PUB--1004
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS