MEASUREMENT OF THE DIRECT PHOTON SPECTRUM FROM UPSILON(1S) DECAYS

被引：18

作者：

BIZZETI, A

机构：

[1] INFN, University of Florence

[2] Deutsches Elektronen Synchrotron DESY

[3] Department of Physics, HEPL, Stanford Linear Accelerator Center, Stanford

[4] University 5f Nijmegen and NIKHEF, NL-6525 ED Nijmegen, The Netherlands12 12 Supported by Stichting voor Fundamenteel Onderzoek der Materie, Nederlandse Organisatie voor Zuiver-Wetenschappelijk Onderzoek (FOM-ZWO)

[5] Cracow Institute of Nuclear Physics

来源：

PHYSICS LETTERS B | 1991年 / 267卷 / 02期

关键词：

D O I：

10.1016/0370-2693(91)91262-T

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Using the Crystal Ball detector at the e+e- storage ring DORIS II, we have measured the energy spectrum of direct photons from UPSILON(1S) decays. According to QCD, these photons result from the decays of the UPSILON(1S) resonance into one photon and two gluons, UPSILON(1S) --> gamma-gg --> gamma + hadrons. The shape of our spectrum does not agree with that calculated in lowest order QCD, but can be described well by a prediction incorporating gluon self-interaction. Using this fit, the ratio R-gamma = GAMMA(UPSILON --> gamma-gg)/GAMMA(UPSILON --> ggg) is determined to be (2.7 +/- 0.2 +/- 0.4)%. From this ratio we deduce the strong coupling constant in the MSBAR scheme at Q2 = 2.2 GeV2 and find alpha-s = 0.25 +/- 0.02 +/- 0.04.

引用

页码：286 / 292

页数：7

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