A DIRECT MEASUREMENT OF THE INVISIBLE WIDTH OF THE Z FROM SINGLE-PHOTON COUNTING

被引：48

作者：

BUSKULIC, D

DEBONIS, I

DECAMP, D

GHEZ, P

GOY, C

LEES, JP

MINARD, MN

PIETRZYK, B

ARIZTIZABAL, F

COMAS, P

CRESPO, JM

DELFINO, M

EFTHYMIOPOULOS, I

FERNANDEZ, E

FERNANDEZBOSMAN, M

GAITAN, V

GARRIDO, L

MATTISON, T

PACHECO, A

PADILLA, C

PASCUAL, A

CREANZA, D

DEPALMA, M

FARILLA, A

IASELLI, G

MAGGI, G

NATALI, S

NUZZO, S

QUATTROMINI, M

RANIERI, A

RASO, G

ROMANO, F

RUGGIERI, F

SELVAGGI, G

SILVESTRIS, L

TEMPESTA, P

ZITO, G

CHAI, Y

HU, H

HUANG, D

HUANG, X

LIN, J

WANG, T

XIE, Y

XU, D

XU, R

ZHANG, J

ZHANG, L

ZHAO, W

BLUCHER, E

机构：

[1] UNIV AUTONOMA BARCELONA, INST FIS ALTES ENERGIES, E-08193 BARCELONA, SPAIN

[2] INFN, SEZ BARI, I-70126 BARI, ITALY

[3] UNIV BARI, DIPARTIMENTO FIS, I-70126 BARI, ITALY

[4] CHINESE ACAD SCI, INST HIGH ENERGY PHYS, BEIJING, PEOPLES R CHINA

[5] CERN, CH-1211 GENEVA 23, SWITZERLAND

[6] UNIV CLERMONT FERRAND, IN2P3, CNRS, PHYS CORPUSCULAIRE LAB, F-63177 CLERMONT FERRAND, FRANCE

[7] NIELS BOHR INST, DK-2100 COPENHAGEN, DENMARK

[8] DEMOKRITOS NATL CTR SCI RES, GR-15310 ATHENS, GREECE

[9] ECOLE POLYTECH, PHYS NUCL & HAUTES ENERGIES LAB, F-91128 PALAISEAU, FRANCE

[10] UNIV EDINBURGH, DEPT PHYS, EDINBURGH EH9 3JZ, MIDLOTHIAN, SCOTLAND

[11] UNIV FLORENCE, INFN, DIPARTIMENTO FIS, SEZ FIRENZE, I-50125 FLORENCE, ITALY

[12] FLORIDA STATE UNIV, SUPERCOMP COMPUTAT RES INST, TALLAHASSEE, FL 32306 USA

[13] FLORIDA STATE UNIV, DEPT PHYS, TALLAHASSEE, FL 32306 USA

[14] INFN, LAB NAZL FRASCATI, I-00044 FRASCATI, ITALY

[15] UNIV GLASGOW, DEPT PHYS & ASTRON, GLASGOW G12 8QQ, SCOTLAND

[16] UNIV HEIDELBERG, INST HECHENERGIEPHYS, W-6900 HEIDELBERG, GERMANY

[17] UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, DEPT PHYS, LONDON SW7 2BZ, ENGLAND

[18] UNIV INNSBRUCK, DEPT EXPTL PHYS, A-6020 INNSBRUCK, AUSTRIA

[19] UNIV LANCASTER, DEPT PHYS, LANCASTER LA1 4YB, ENGLAND

[20] UNIV MAINZ, INST PHYS, W-6500 MAINZ, GERMANY

[21] FAC SCI LUMINY, IN2P3, CNRS, CTR PHYS PARTICULES, F-13288 MARSEILLE 9, FRANCE

[22] MAX PLANCK INST PHYS & ASTROPHYS, WERNER HEISENBERG INST, W-8000 MUNICH, GERMANY

[23] UNIV PARIS 11, IN2P3, CNRS, ACCELERATEUR LINEAIRE LAB, F-91405 ORSAY, FRANCE

[24] UNIV PISA, INFN, SEZ PISA, I-56010 PISA, ITALY

[25] SCUOLA NORMALE SUPER PISA, I-56010 PISA, ITALY

[26] UNIV LONDON, ROYAL HOLLOWAY & BEDFORD NEW COLL, EGHAM TW20 0EX, SURREY, ENGLAND

[27] RUTHERFORD APPLETON LAB, DEPT PARTICLE PHYS, DIDCOT OX11 0QX, OXON, ENGLAND

[28] CE SACLAY, DAPNIA, SERV PHYS PARTICULES, F-91191 GIF SUR YVETTE, FRANCE

[29] UNIV CALIF SANTA CRUZ, INST PARTICLE PHYS, SANTA CRUZ, CA 95064 USA

[30] UNIV SHEFFIELD, DEPT PHYS, SHEFFIELD S3 7RH, S YORKSHIRE, ENGLAND

[31] UNIV GESAMTHSCH SIEGEN, FACHBEREICH PHYS, W-5900 SIEGEN 21, GERMANY

[32] UNIV TRIESTE, DIPARTIMENTO FIS, I-34127 TRIESTE, ITALY

[33] INFN, SEZ TRIESTE, I-34127 TRIESTE, ITALY

[34] UNIV WISCONSIN, DEPT PHYS, MADISON, WI 53706 USA

[35] UNIV WASHINGTON, SEATTLE, WA 98195 USA

[36] UNIV TURIN, IST FIS GEN, I-10124 TURIN, ITALY

[37] CNR, IST COSM GEOFIS, TURIN, ITALY

[38] CERN, DIV PPE, CH-1211 GENEVA 23, SWITZERLAND

[39] UNIV NAPLES, DIPARTIMENTO SCI FIS, I-80138 NAPLES, ITALY

[40] UNIV SASSARI, IST MATEMAT & FIS, I-07100 SASSARI, ITALY

来源：

PHYSICS LETTERS B | 1993年 / 313卷 / 3-4期

关键词：

D O I：

10.1016/0370-2693(93)90027-F

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The ALEPH detector at LEP is used to study single photon events in e+e- collisions at the Z resonance. In a total data sample of 15.7 pb-1 taken in 1990 and 1991 scanning the resonance, 400 events were recorded where each has a single deposition of more than 1.5 GeV measured in the polar angular region \costheta(gamma)\ < 0.74 of the electromagnetic calorimeter. It is shown that this number of events can be accounted for by known processes. After subtraction of background events, the invisible width of the Z is determined to be 450 +/- 34(stat.) +/- 34(syst.) MeV. Using Z resonance parameters derived by ALEPH, the corresponding number of light neutrino generations is found to be 2.68 +/- 0.20(stat.) +/- 0.20(syst.).

引用

页码：520 / 534

页数：15

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