→kπ道中d0d0混合以及b→jψd0π和b0→jψd0道的实验测量

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1、优秀毕业论文假定DO系统CP破缺可忽略，我们得到95％置信度的界限z尼<0．72×10_3和-9．9X10_3

2、％置信度下的衰变分支比上限8(Bo_J／妒西”)<2．O×10—5和13(B+一j／移-万“7r+)<2．5×10～。此结果排除了用B介子中存在原初粲夸克对的假设来解释B介予单举衰变中J／妒动量谱低端增强现象的可能。同时，我们还给出了相应非共振态衰变道的分支比。关键词：Do一万。混合，错误符号，固有时问，Belie，Bo，B一，原初粲夸克精品参考文献资料优秀毕业论文AbstractWereporttheresultsofasem'chforDu．Domixingbasedon400ib一1ofdataa

3、ccumulatedbytheBdiedetectorattileKEKBasymmetric—energye+e—collider．ThepaxametersthatdescribeDo—Domixing，z7andY7，aremeastlredbystudyingaproper：timeevolutionofthewrong—signdecayprocessDo_K+w一．Intheanalysis．Doareselectedfromcontinuumceevents．WbreconstructDo

4、fromthedecaychain+D¨_7寸Do，Do一Ⅳ+7r一．Thechargeoftilesoftpion71sisusedtotagtheflavoroftheneutralDatproduction．Theright．signdecayD”_Ⅳ一7r+isalsoreconstructedforRwsmeasurementanda8areferencechannel，whereRWsisthefateofwrong—sigtttoright—signdecay．W．eobtaintheDo

5、decayandproductionverticesby、tlu'eedimensionalvertexfit、tocalculatethepropertimeanditsuncgrtainty．weusehugeamountsofbackgroundMonteCarlo(MC)tostudybackgroundsources．Thebackgroundcanbecategorizedintorandomslow7r+，D“≥3body，D之、andcombinatorial．Themassandtim

6、edistributioncharacteristicsofthesefourtypesofbackgrohndsarewel】understood．Besides，theirtwodimensionalmassdistributionsagecm'efullyparameterized．Twodimensionalfitstotheright—signattdwrong-signdistributionsyield1073993士1108Du_Ⅳ一丁r+and4024士88Du_K+7r—signal

7、events，whichresultinRws=(0．375土o．008)％．Tileratioofwrong—signsignaltobackgroundisimprovedtobe1．1．duetotheoptimizedselectioncriteria．Byusingtheinformationofdataeventsoutsidesignalregion，theselectioncriteriaareobtainedtomaximumthefigureofnlerit．aswhichcallm

8、inimizethestatistica．1mlcertaintyofnlixingparaaneters．Antnll)innedmaximumlikelihoodmethodisusedintheliretimefitwithevent—by-eventresolutionfunctions．TheprobabilitydensityfLlnctionfPDFlisconstructedflomthetimedis—tributions