Measurement of the average polarization of b baryons in hadronic Z0 decays

被引：39

作者：

Abbiendi, G ^{[1
]}

Ackerstaff, K

Alexander, G

Allison, J

Altekamp, N

Anderson, KJ

Anderson, S

Arcelli, S

Asai, S

Ashby, SF

Axen, D

Azuelos, G

Ball, AH

Barberio, E

Barlow, RJ

Bartoldus, R

Batley, JR

Baumann, S

Bechtluft, J

Behnke, T

Bell, KW

Bella, G

Bellerive, A

Bentvelsen, S

Bethke, S

Betts, S

Biebel, O

Biguzzi, A

Bird, SD

Blobel, V

Bloodworth, IJ

Bobinski, M

Bock, P

Böhme, J

Bonacorsi, D

Boutemeur, M

Braibant, S

Bright-Thomas, P

Brigliadori, L

Brown, RM

Burckhart, HJ

Burgard, C

Bürgin, R

Capiluppi, P

Carnegie, RK

Carter, AA

Carter, JR

Chang, CY

Charlton, DG

Chrisman, D

机构：

[1] Univ Bologna, Dipartimento Fis, I-40126 Bologna, Italy

[2] Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England

[3] Univ Bonn, Inst Phys, D-53115 Bonn, Germany

[4] Univ Calif Riverside, Dept Phys, Riverside, CA 92521 USA

[5] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England

[6] Carleton Univ, Dept Phys, Ottawa Carleton Inst Phys, Ottawa, ON K1S 5B6, Canada

[7] Carleton Univ, Ctr Res Particle Phys, Ottawa, ON K1S 5B6, Canada

[8] CERN, European Org Particle Phys, CH-1211 Geneva 23, Switzerland

[9] Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA

[10] Univ Chicago, Dept Phys, Chicago, IL 60637 USA

[11] Univ Freiburg, Fak Phys, D-79104 Freiburg, Germany

[12] Heidelberg Univ, Inst Phys, D-69120 Heidelberg, Germany

[13] Indiana Univ, Dept Phys, Bloomington, IN 47405 USA

[14] Queen Mary Univ London, London E1 4NS, England

[15] Tech Hsch Aachen, Inst Phys 3, D-52056 Aachen, Germany

[16] UCL, London WC1E 6BT, England

[17] Univ Manchester, Dept Phys, Schuster Lab, Manchester M13 9PL, Lancs, England

[18] Univ Maryland, Dept Phys, College Pk, MD 20742 USA

[19] Univ Montreal, Phys Nucl Lab, Montreal, PQ H3C 3J7, Canada

[20] Univ Oregon, Dept Phys, Eugene, OR 97403 USA

[21] Rutherford Appleton Lab, CLRC, Didcot OX11 0QX, Oxon, England

[22] Technion Israel Inst Technol, Dept Phys, IL-32000 Haifa, Israel

[23] Tel Aviv Univ, Dept Phys & Astron, IL-69978 Tel Aviv, Israel

[24] Univ Tokyo, Int Ctr Elementary Particle Phys, Tokyo 113, Japan

[25] Univ Tokyo, Dept Phys, Tokyo 113, Japan

[26] Kobe Univ, Kobe, Hyogo 657, Japan

[27] Brunel Univ, Inst Phys & Environm Sci, Uxbridge UB8 3PH, Middx, England

[28] Weizmann Inst Sci, Particle Phys Dept, IL-76100 Rehovot, Israel

[29] Univ Hamburg, DESY, Inst Expt Phys 2, D-22607 Hamburg, Germany

[30] Univ Victoria, Dept Phys, Victoria, BC V8W 3P6, Canada

[31] Univ British Columbia, Dept Phys, Vancouver, BC V6T 1Z1, Canada

[32] Univ Alberta, Dept Phys, Edmonton, AB T6G 2J1, Canada

[33] Duke Univ, Dept Phys, Durham, NC 27708 USA

[34] Res Inst Particle & Nucl Phys, H-1525 Budapest, Hungary

[35] Inst Nucl Res, H-4001 Debrecen, Hungary

[36] Univ Munich, Sekt Phys, D-85748 Garching, Germany

[37] TRIUMF, Vancouver, BC V6T 2A3, Canada

[38] Lajos Kossuth Univ, Dept Expt Phys, Debrecen, Hungary

来源：

PHYSICS LETTERS B | 1998年 / 444卷 / 3-4期

基金：

以色列科学基金会; 美国国家科学基金会; 加拿大自然科学与工程研究理事会;

关键词：

D O I：

10.1016/S0370-2693(98)01387-2

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

In the Standard Model, b quarks produced in e(+)e(-) annihilation at the Z(0) peak have a large average longitudinal polarization of -0.94. Some fraction of this polarization is expected to be transferred to b-flavored baryons during hadronization. The average longitudinal polarization of weakly decaying b baryons, [P-L(Lambda b)], is measured in approximately 4.3 million hadronic Z(0) decays collected with the OPAL detector between 1990 and 1995 at LEP. Those b baryons that decay semileptonically and produce a Lambda baryon are identified through the correlation of the baryon number of the Lambda and the electric charge of the lepton. In this semileptonic decay, the ratio of the neutrino energy to the lepton energy is a sensitive polarization observable. The neutrino energy is estimated using missing energy measurements. From a fit to the distribution of this ratio, the value [p(L)(Lambda b)] = -0.56(-0.13)(+0.20) +/- 0.09 is obtained, where the first error is statistical and the second systematic. (C) 1998 Elsevier Science B.V. All rights reserved.

引用

页码：539 / 554

页数：16

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