A first measurement of the Lambda(Lambda)over-bar and Lambda Lambda ((Lambda)over-bar(Lambda)over-bar) spin compositions in hadronic Z(0) decays

被引：35

作者：

Alexander, G

Allison, J

Altekamp, N

Ametewee, K

Anderson, KJ

Anderson, S

Arcelli, S

Asai, S

Axen, D

Azuelos, G

Ball, AH

Barberio, E

Barlow, RJ

Bartoldus, R

Batley, JR

Beaudoin, G

Bechtluft, J

Beeston, C

Behnke, T

Bell, AN

Bell, KW

Bella, G

Bentvelsen, S

Berlich, P

Bethke, S

Biebel, O

Blobel, V

Bloodworth, IJ

Bloomer, JE

Bock, P

Bosch, HM

Boutemeur, M

Bouwens, BT

Braibant, S

Brown, RM

Burckhart, HJ

Burgard, C

Burgin, R

Capiluppi, P

Carnegie, RK

Carter, AA

Carter, JR

Chang, CY

Charlesworth, C

Charlton, DG

Chrisman, D

Chu, SL

Clarke, PEL

Cohen, I

Conboy, JE

机构：

[1] School of Physics and Space Research, University of Birmingham

[2] Dipartimento di Fisica dell' Università di Bologna and INFN

[3] Physikalisches Institut, Universität Bonn

[4] Department of Physics, University of California

[5] Cavendish Laboratory

[6] Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, Ottawa

[7] Centre for Research in Particle Physics, Carleton University, Ottawa

[8] CERN, European Organisation for Particle Physics

[9] Enrico Fermi Institute and Department of Physics, University of Chicago

[10] Fakultätflir Physik, Albert Ludwigs Universität

[11] Physikalisches Institut, Universität Heidelberg

[12] Indiana University, Department of Physics, Swain Hall West 117

[13] Queen Mary and Westfield College, University of London

[14] Technische Hochschule Aachen, III Physikalisches Institut, Sommerfeldstrasse 26-28

[15] University College London

[16] Department of Physics, Schuster Laboratory, The University

[17] Department of Physics, University of Maryland, College Park

[18] Laboratoire de Physique Nucléaire, Université de Montreal, Montreal

[19] University of Oregon, Department of Physics

[20] Rutherford Appleton Laboratory, Chilton, Didcot

[21] CEA, DAPNIA/SPP, CE-Saclay

[22] Department of Physics, Technion-Israel Institute of Technology

[23] Department of Physics and Astronomy, Tel Aviv University

[24] International Centre for Elementary Particle Physics and Department of Physics, University of Tokyo

[25] Kobe University

[26] Brunei University, Uxbridge

[27] Particle Physics Department, Weizmann Institute of Science

[28] Universität Hamburg/DESY, II Institut für Experimental Physik, Notkestrasse 85

[29] University of Victoria, Department of Physics, P O Box 3055

[30] University of British Columbia, Department of Physics

[31] University of Alberta, Department of Physics

[32] Duke University, Department of Physics, Durham

[33] Research Institute for Particle and Nuclear Physics, PO Box 49

[34] Institute of Nuclear Research, PO Box 51

[35] TRIUMF, Vancouver

[36] Institute of Nuclear Research, Debrecen

[37] Department of Experimental Physics, Lajos Kossuth University, Debrecen

[38] Ludwig-Maximilians-Universität, München

来源：

PHYSICS LETTERS B | 1996年 / 384卷 / 1-4期

基金：

美国国家科学基金会;

关键词：

D O I：

10.1016/0370-2693(96)00860-X

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The spin composition of <Lambda(Lambda)over bar>, Lambda Lambda and <(Lambda)over bar><(Lambda)over bar> pairs at low invariant mass values has been measured for the first time in multihadronic Z(0) decays with the OPAL detector at LEP. No single spin state has been observed in the <Lambda(Lambda)over bar> sample, verifying that the low mass enhancement in this sample, attributed to local baryon number compensation, is not a resonance state. The fraction of the spin 1 contribution to the <Lambda(Lambda)over bar> pairs was found to be consistent with the value 0.75, as expected from a statistical spin mixture. This may be the net effect of many different QCD processes which contribute to the hyperon anti-hyperon pair production. The spin composition of the identical Lambda Lambda and <(Lambda)over bar(Lambda)over bar> pairs, well above threshold, is found to be similar to that of the <Lambda(Lambda)over bar> sample. A Lambda Lambda emitter dimension is estimated from the data assuming the onset of the Pauli exclusion principle near threshold.

引用

页码：377 / 387

页数：11

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