MEASUREMENT OF LAMBDA-POLARIZATION FROM Z-DECAYS

Authors
BUSKULIC D DEBONIS I DECAMP D GHEZ P GOY C LEES JP LUCOTTE A MINARD MN ODIER P PIETRZYK B CHMEISSANI M CRESPO JM DELFINO M EFTHYMIOPOULOS I FERNANDEZ E FERNANDEZBOSMAN M GARRIDO L JUSTE A MARTINEZ M ORTEU S PACHECO A PADILLA C PALLA F PASCUAL A PERLAS JA RIU I SANCHEZ F TEUBERT F COLALEO A GELAO G GIRONE M IASELLI G MAGGI G NUZZO S RANIER A RASO G ROMANO F RUGGIERI E SELVAGGI G SILVESTRIS L TEMPESTA P ZITO G HUANG X LIN J OUYANG Q WANG T XIE Y XU R XUE S ZHANG J ZHANG L ZHAO W ALEMANY R BAZARKO AO BONVICINI G CATTANEO M COMAS P COYLE P DREVERMANN H FORTY RW FRANK M HAGELBERG R HARVEY J JACOBSEN R JANO P JOST B KNERINGER E KNOBLOCH J LEHRAUS I MARTIN EB MATO P MINTEN A MIQUEL R MIR LM MONETA L OEST T PALAZZI P PATER JR PUSZTASZERI JF RANJARD F RENSING P ROLANDI L SCHLATTER D SCHMELLING M SCHNEIDER O TEJESSY W TOMALIN IR VENTURI A WACHSMUTH H WAGNER A WILDISH T WITZELING W WOTSCHACK J AJALTOUNI Z BARRES A BOYER C FALVARD A GAY P GUICHENEY C HENRARD P JOUSSET J MICHEL B MONTEIL S MONTRET JC PALLIN D PERRET P PODLYSKI F PRORIOL J ROSSIGNOL JM FEARNLEY T HANSEN JB HANSEN JD HANSEN JR HANSEN PH NILSSON BS WAANANEN A KYRIAKIS A MARKOU C SIMOPOULOU E SIOTIS I VAYAKI A ZACHARIADOU K BLONDEL A BONNEAUD G BRIENT JC BOURDON P ROUGE A RUMPF M TANAKA R VALASSI A VERDERI M VIDEAU H CANDLIN DJ PARSONS MI FOCARDI E PARRINI G CORDEN M GEORGIOPOULOS C JAFFE DE ANTONELLI A BENCIVENNI G BOLOGNA G BOSSI F CAMPANA F CAPON G CASPER D CHIARELLA V FELICI G LAURELLI P MANNOCCHI G MURTAS F MURTAS GP PASSALACQUA L PEPEALTARELLI M CURTIS L DORRIS SJ HALLEY AW KNOWLES IG LYNCH JG OSHEA V RAINE C REEVES P SCARR JM SMITH K THOMPSON AS THOMAS F THORN S TURNBULL RM BECKER U GEWENIGER C GRAEFE G HANKE P HANSPER G HEPP V KLUGE EE PUTZER A RENSCH B SCHMIDT M SOMMER J STENZEL H TITTEL K WERNER S WUNSCH M ABBANEO D BEUSELINCK R BINNIE DM CAMERON W DORNAN PJ MOUTOUSSI A NASH J SEDGBEER JK STACEY AM WILLIAMS MD DISSERTORI G GIRTLER P KUHN D RUDOLPH G BOWDERY CK BRODBECK TJ COLRAIN P CRAWFORD G FINCH AJ FOSTER F HUGHES G SLOAN T WHELAN EP WILLIAMS MI GALLA A GREENE AM KLEINKNECHT K QUAST G RENK B ROHNE E SANDER HG VANGEMMEREN P ZEITNITZ C AUBERT JJ BENCHEIKH AM BENCHOUK C BONISSENT A BUJOSA G CALVET D CARR J DIACONU C ETIENNE E KONSTANTINIDIS N NICOD D PAYRE P ROUSSEAU D TALBY M SADOUKI A THULASIDAS M TRABELSI K ABT I ASSMANN R BAUER C BLUM W DIETL H DYDAK F GANIS G GOTZHEIN C JAKOBS K KROHA H LUTJENS G LUTZ G MANNER W MOSER HG RICHTER R ROSADOSCHLOSSER A SCHAEL S SETTLES R SEYWERD H STDENIS R WIEDENMANN W WOLF G BOUCROT J CALLOT O CORDIER A DAVIER M DUFLOT L GRIVAZ JF HEUSSE P JACQUET M KIMFN DW LEDIBERDER F LEFRANCOIS J LUTZ AM NIKOLIC I PARK HJ PARK IC SCHUNE MH SIMION S VEILLET JJ VIDEAU I AZZURRI P BAGLIESI G BATIGNANI G BETTARINI S BOZZI C CALDERINI G CARPINELLI M CIOCCI MA CIULLI V DELLORSO R FANTECHI R FERRANTE I FOA L FORTI F GIASSI A GIORGI MA GREGORIO A LIGABUE F LUSIANI A MARROCCHESI PS MESSINEO A RIZZO G SANGUINETTI G SCIABA A SPAGNOLO P STEINBERGER J TENCHINI R TONELLI G VANNINI C VERDINI PG WALSH J BETTERIDGE AP BLAIR GA BRYANT LM CERUTTI F CHAMBERS JT GAO Y GREEN MG JOHNSON DL MEDCALF T PERRODO P STRONG JA VONWIMMERSPERGTOELLER JH BOTTERILL DR CLIFFT RW EDGECOCK TR HAYWOOD S MALEY P NORTON PR THOMPSON JC WRIGHT AE BLOCHDEVAUX B COLAS P EMERY S KOZANECKI W LANCON E LEMAIRE MC LOCCI E MARX B PEREZ P RANDER J RENARDY JF ROUSSARIE A SCHULLER JP SCHWINDLING J TRABELSI A VALLAGE B JOHNSON RP KIM HY LITKE AM MCNEIL MA TAYLOR G BEDDALL A BOOTH CN BOSWELL R BREW CAJ CARTWRIGHT S COMBLEY F KOKSAL A LETHO M NEWTON WM RANKIN C REEVE J THOMPSON LF BOHRER A BRANDT S BUSCHER V COWAN G GRUPEN C LUTTERS G MINGUETRODRIGUEZ J RIVERA F SARAIVA P SMOLIK L STEPHAN F ALEPPO M APOLLONIO M BOSISIO L DELLAMARINA R GIANNINI G GOBBO B MUSOLINO G RAGUSA F ROTHBERG J WASSERBAECH S ARMSTRONG SR BELLANTONI L ELMER P FENG Z FERGUSON DPS GAO YS GONZALEZ S GRAHL J GREENING TC HARTON JL HAYES OJ HU H MCNAMARA PA NACHTMANA JM OREJUDOS W PAN YB SAADI Y SCHMITT M SCOTT IJ SHARMA V TURK JD WALSH AM WU SL WU X YAMARTINO JM ZHENG M ZOBERNIG G
Citation
D. Buskulic et al., MEASUREMENT OF LAMBDA-POLARIZATION FROM Z-DECAYS, Physics letters. Section B, 374(4), 1996, pp. 319-330
Citations number
29
Categorie Soggetti
Physics
Journal title
Physics letters. Section B → ACNP
ISSN journal
03702693
Volume
374
Issue
4
Year of publication
1996
Pages
319 - 330
Database
ISI
SICI code
0370-2693(1996)374:4<319:MOLFZ>2.0.ZU;2-3
Abstract
The polarization of Lambda baryons from Z decays is studied with the A LEPH apparatus. Evidence of longitudinal polarization of s quarks from Z decay is observed for the first time. The measured longitudinal Lam bda polarization is P-L(Lambda) = -0.32 +/- 0.07 for z = p/pbeam > 0.3 . This agrees with the prediction of -0.39 +/- 0.08 from the standard model and the constituent quark model, where the error is due to uncer tainties in the mechanism for Lambda production. The observed Lambda p olarization is diluted with respect to the primary s quark polarizatio n by Lambda baryons without a primary s quark. Measurements of the Lam bda forward-backward asymmetry and of the correlation between back-to- back Lambda<(Lambda)over bar> pairs are used to check this dilution. I n addition the transverse Lambda polarization is measured. An indicati on of transverse polarization, more than two standard deviations away from zero, is found along the normal to the plane defined by the thrus t axis and the Lambda direction.