矢量粲偶素若干重子衰變道的測量.pdf

1、華中師范大學博士學位論文矢量粲偶素若干重子衰變道的測量姓名：徐新平申請學位級別：博士專業(yè)：粒子物理與原子核物理指導教師：劉峰苑長征20090401⑧博士學位論文DocTORALDISSERTATIONAbstractWith58millionJ／砂and14million移(2S)eventscollectedwiththeBESIIde—tectorattheBEPCbranchingfractionsorupperlimitsonb

2、ranchingfractionsforthebaryonicdecaysale—AXrro，al妒一AAr／，妒(2s)一人人丌o，妒(2s)一AA0，，／砂—∑∑一andJ／移—’三D三oaremeasuredIntheanalysisofJ／砂—人人7ro，wefoundthattheobserved7ruWasseriouslycontaminatedbythebackgroundsJ／妒—E07ro人ccandJ／砂—∑7r一

3、人CCConsideringthecontributionsofthesecrucialbackgrounds，WCfoundthatthebranchingfractionofJl砂decayingtoAATruissmallerthanpreviousmeasurementsIncontrasttothelargevalue((22士06)X10—4)ofbranchingfractionof‘，／砂—崢人人7ruiIlPDG200

4、6，wedetermined，atthe90％confidencelevel，B(JAb_AArto)64X10一Inthemeasurement3|啼_AAr／，weoptimizedtheeventselections，andobservedthesignalof77inthe“／7invariantmassforthefirsttimeThestatisticalsignificanceis48a，andthebranchingf

5、ractionismeasuredtobe，t3(al妒_AArl)=(26240604044)X10～，where血efirsterrorisstafisficalandthesecondsystematicComparingt11edistinctvaluesofthebranchingfractionof。s／由_AATr鼬and3|由_AAr／wefoundthatourresultsareinaccordwiththetheo

6、reticalpredictionsoftherelativelargebranchingfractionofstronginteractionThereforeourresultsindicatethatthereisnoabnormalphysicsin3|由_AS7r受andJ／O_AAr／decaysSimilarlywealsoanalyzed妒(2s)decayingintoA瓦rroandAAr／Nosignalswere

7、foundin砂(2S)decays，andL11eupperlimitsatthe90％confidencelevelaredeterminedtobe，t3(妒(2s)_AArro)4910～，t3(妒(gs)一人面)12X10～Furthermore，weobservedthebaryonpairprocessessic_∑∑一andsic三。量oforthefirsttime，andmeasuredthebranchingfra

8、ctionstObe，B(SlV；_∑寶一)=(1504o104022)X101，8(s／妒_：oeo)=(1204o12土021)10～，wherethefirstellorisstatisticalandthesecondsystematicTheseresultSarecon—sistentwiththebranchingfractionsoftheirisospinpartnerssic—Eo￡oandsic_三一言withex