First measurement of the left-right cross section asymmetry in Z boson production by e+e- collisions.
First measurement of the left-right cross section asymmetry in Z boson production by e+e- collisions.
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首次测量电子碰撞产生 Z 玻色子时的左右横截面不对称性。
DOI：
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发表时间：
1993
影响因子：
8.6
通讯作者：
Cartwright
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文献类型：
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作者：
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. . F+表示左右截面的第一个测量值为！嗯！(ALR)2玻色子生产eSecollisions。在SL.AC直线对撞机上用SLD探测器在91.55 GeV的质心能量下进行测量，该探测器利用纵向极化电子束。平均光束偏振度为（22.4 ± 0.7）%。使用10，224 2十分之一的样品，测量值'~LR _ @为0. 00f0.044（统计）f0.004（系统）其确定有效的Lyeal混合角为sin 2 t9$ = 0.2378 f 0.0056（stat.）f 0.0005（qxt.）。提交给Physica。Revierv Letters +Th. IS部分由能源部合同支持：DE-FGO”-91 ER 40676（BU）、DEFG 03 - 92 ER 40701（CIT）、DE-FG 03 - 91 ER 40618（UCSB）、DE-FG 02 - 91 ER 40672（科罗拉多）。DEFG 02 - 91 ER 40677（伊利诺伊州）、DE-FG 02 - 91 ER 40661（印第安纳州）、DE-AC 03 - 76 SF 00098（LBL）、DEFG 02 - 92 ER 40715（马萨诸塞州）、DE-ACO？- 76ER03069（MIT）。DE-FGOG-85 ER 40224（俄勒冈州），-fijGAC $+ Z6 SF@515（SLAC），DE-FG 05 - 91 ER 40627（田纳西州），DE-ACOS-76 ER 00881（威斯康星州），DE-FG%-92 ERi 0704（耶鲁大学）;国家科学基金会赠款：PHY-91-13428（UCSC），PHI*-8921320（哥伦比亚），PHY-92-04239（C increase），PHY-88-17930（Rutgers），PHY-88-19316（\;anderbilt），PHY-92-03212（华盛顿）和意大利国家核财政研究所（Istituto Nazionale di Fisica Nucleare）。（博洛尼亚、费拉拉、弗拉斯卡蒂、比萨、帕多瓦和佩鲁贾）;日美高能物理合作研究计划（KEK、名古屋和东北）;加拿大自然科学和工程研究理事会（不列颠哥伦比亚省、维多利亚和TRIUMF）;以及联合王国科学和工程研究理事会（Brunel和RAL）。这封信介绍了第一次测量的左右截面不对称性（ALR）的生产2玻色子的e+碰撞。测量是在1992年由SLD合作组在SLAC直线对撞机（SLC）上进行的. T&左右对称定义为[l]，. . ALR =（a~ OR）/（~L +a~），（1）式中CTL和OR分别是Z玻色子（2极）与左手和右手电子的e ~+产生截面。标准模型预测，这个量取决于2玻色子与电子流的轴向矢量耦合和轴向矢量耦合。. ALR= 2 vdk = 2 [1 - 4sin“t1 $] v$ + a：1+ [1 -4sin”t1$]”（2）其中有效电弱混合参数被定义为sin”t1 $; F（1ve/ae）/4。注意，ALR具有以下性质：它是-sin 2b $的敏感函数，预期它很大（0.10 -0.15），并且它不依赖于2到其最终状态的耦合。我们通过对电子B&am的两个纵向极化态中的每一个的t，he 2玻色子的强子和T+Tdeca，ys计数来测量ALR。这种测量需要了解溶质光束的偏振，但不需要了解绝对光度、探测器的a. ceptance或效率[3]。_ -T&iLc. ~最近升级为生产a.ccelera.te和碰撞a.自旋极化电子束[4，5]。利用极化电子，电子是由砷化镓催化剂的光电子发射产生的[6，7]。螺旋度
. . F+present the first measurement of the left-right cross sect ion as!mmetr! (ALR) for 2 boson production by eSecollisions. The measurement was performed at a center-of-mass energy of 91.55 GeV with the SLD detector at the SL.AC Linear Collider which utilized a longitudinally polarized electron beam. The a\.erage beam polarization was (22.4f0.7)%. U sin g a sample of 10,224 2 deca\x, ne measure ‘~LR _ @be 0.~00f0.044(stat.)f0.004(syst.) which determines the effecti\-e Lyeal; mixing angle to be sin2 t9$ = 0.2378 f O.O056(stat.) f O.O005(qxt.). Submitted to Physica. Revierv Letters +Th. IS supported in part by Department of Energy contracts: DE-FGO”-91ER40676 (BU), DEFG03-92ER40701 (CIT), DE-FG03-91ER40618 (UCSB), DE-FG02-91ER40672 (Colorado). DEFG02-91ER40677 (Illinois), DE-FG02-91ER40661 (Indiana), DE-AC03-76SF00098 (LBL), DEFG02-92ER40715 (Massachusetts), DE-ACO?-76ER03069 (MIT). DE-FGOG-85ER40224 (Oregon), -fiIjGAC$+Z6SF@515 (SLAC), DE-FG05-91ER40627 (Tennessee), DE-ACOS-76ER00881 (Wisconsin), DE-FG%-92ERi0704 (Yale); National Science Foundation grants: PHY-91-13428 (UCSC), PHI*-8921320 (Columbia), PHY-92-04239 (C incinnati), PHY-88-17930 (Rutgers), PHY-88-19316 (\;anderbilt), PHY-92-03212 (Washington); and by the Istituto Nazionale di Fisica Nucleare of It.aly (Bologna, Ferrara, Frascati, Pisa, Padova, and Perugia); the Japan-US Cooperative Research Project on High Energ] Physics (KEK, Nagoya, and Tohoku); the Natural Sciences and Engineering Research Council of Canada (British Columbia, Victoria, and TRIUMF); and the Science and Engineering Research Council of the United Kingdom (Brunel and RAL). This letter presents the first measurement of the left-right cross section asymmetry (ALR) in the production of 2 bosons by e+ecollisions. The measurement was performed in 1992 by the SLD Collabora.tion at the SLAC Linear -Collider (SLC). T&left-rightasymmetry is defined as [l], . . ALR =(a~ OR)/(~L +a~), (1) where CTL and OR are the e+eproduction cross sections for Z bosons (at the 2 pole) with left-handed and right-handed electrons, respectiveI!.. To leading order, the Standard Model predicts that this quantity depends upon the \~ctor (of ) and axial-vector (a,) couplings of the 2 boson to the electron current. . ALR= 2vdk = 2 [l 4 sin” O$] v$ + a: 1+ [l-4sin’t1$]” (2) where the effective electroweak mixing parameter is defined’ as sin’ 0;; F (1 ve/ae)/4. Note that ALR has the following properties: it is a sensitive function of -_ sin2b$, it is expected to be large (O.lO-0.15), and it does not depend upon the couplings df the 2 to its final states. We measure ALR by counting hadronic and T+Tdeca,ys of t,he 2 boson for each of the two longitudinal polarization states of the electroll b&am. The measurement requires knowledge of the a.bsolute beam polarization, but does not require knowledge of the absolute luminosity, detector a.cceptance, or efficiency [3]. _ -T&iLc. ~ as recently been upgraded to produce, a.ccelera.te, and collide a. spin-polarized electron beam [4,5]. P u ses of longitudina.lly polarized elect,rons are 1 produced by photoemission from a gallium arsenide cat.hode [6,7]. The helicity