本文關(guān)鍵詞： QCD因子化 B_c介子 γ介子 非輕衰變　出處：《華中師范大學(xué)》2016年博士論文　論文類(lèi)型：學(xué)位論文

【摘要】：重味物理是檢驗(yàn)標(biāo)準(zhǔn)模型、探索CP破壞起源和尋找新物理的重要場(chǎng)所。LHC的運(yùn)行,預(yù)計(jì)每年將產(chǎn)生5×1010 Bc事例數(shù)。同時(shí),在Belle和BaBar已經(jīng)收集了超過(guò)108 T介子的實(shí)驗(yàn)數(shù)據(jù)；而在LHCb上,每.f6-1積分亮度下預(yù)計(jì)會(huì)產(chǎn)生1011巧事例數(shù)；即將運(yùn)行的SuperKEKB上也將會(huì)產(chǎn)生大量的T事例數(shù)。如此充足的數(shù)據(jù)量,使得B。介子和T介子成為重味物理研究的重要的場(chǎng)所。在本文中我們將采用QCD因子化方法來(lái)對(duì)Bc介子和T介子的一些弱衰變過(guò)程進(jìn)行研究和分析。首先,我們介紹了一些基本理論,包括標(biāo)準(zhǔn)模型,CKM矩陣以及重整化群和算符乘積展開(kāi)等。其次,我們介紹了幾種常用的計(jì)算強(qiáng)子矩陣元的方法,并著重介紹了QCD因子化方法。最后,我們給出論文的主題部分,主要由以下兩部分組成：首先,在QCD因子化框架下,對(duì)B→PP, PV的兩體非輕無(wú)粲過(guò)程進(jìn)行分析。在標(biāo)準(zhǔn)模型下,這一類(lèi)衰變過(guò)程是純湮滅過(guò)程,且只有流-流算符有貢獻(xiàn),使得這類(lèi)衰變過(guò)程成為研究重介子湮滅衰變的一個(gè)很好的場(chǎng)所。在本文中,我們將采用兩種方案來(lái)處理湮滅圖計(jì)算中的端點(diǎn)發(fā)散問(wèn)題：方案Ⅰ是通常的QCD因子化方法；方案Ⅱ是采用紅外有限的膠子傳播子和耦合常數(shù)。這兩種不同的方案已經(jīng)被用于處理玩,d,s的衰變過(guò)程,在這里我們用于研究Bc介子的衰變過(guò)程。在計(jì)算中,我們采用了三種不同形式的Bc介子波函數(shù)進(jìn)行比較。結(jié)果表明：在方案Ⅰ下,該類(lèi)衰變過(guò)程的分支比結(jié)果很小,較難在實(shí)驗(yàn)上被探測(cè)到。在方案Ⅱ下,當(dāng)采用紅外有限的膠子傳播子時(shí),湮滅圖的貢獻(xiàn)相對(duì)于方案Ⅰ來(lái)說(shuō)得到了增強(qiáng),但依然小于pQCD給出的計(jì)算結(jié)果。在我們的計(jì)算中,Bc-→π-ω過(guò)程有著最大的衰變分支比Br(Bc-→π-ω)=12.8×10-8,這個(gè)衰變過(guò)程很可能在LHC或即將運(yùn)行的SuperKEKB上被探測(cè)到。接著,我們?cè)赒CD因子化方案下研究了T(nS)→BcM的衰變過(guò)程,并用非相對(duì)論波函數(shù)來(lái)計(jì)算T到介子的躍遷形狀因子。唯象上,T(nS)→BcM的弱衰變過(guò)程僅有流-流算符的貢獻(xiàn),并且是被CKM矩陣元vd,增強(qiáng)的,因此這類(lèi)衰變過(guò)程在T介子的弱衰變中有著相對(duì)較大的分支比。結(jié)果表明：在T(nS)→BcM這類(lèi)衰變中(M=π,ρ,K和K*),T(nS)→Bcp的衰變過(guò)程有著相對(duì)較大的分支比結(jié)果,大約在O(10-10),應(yīng)該最先在實(shí)驗(yàn)上被探測(cè)到。
[Abstract]:Heavy taste physics is a standard model for testing, exploring the origin of CP destruction and the operation of LHC, which is an important site for finding new physics. It is estimated that 5 脳 1010Bc cases will be produced every year. At the same time. More than 108T meson experimental data have been collected at Belle and BaBar; On LHCb, 1011 coincidences are expected to occur per f6-1 integral brightness; A large number of T cases will also be generated on the upcoming SuperKEKB. Such a large amount of data. In this paper, we will use QCD factorization method to study and analyze some weak decay processes of Bc mesons and T mesons. . We introduce some basic theories, including the canonical model CKM matrix, renormalization group and operator product expansion. Secondly, we introduce several common methods for calculating Hadron matrix elements. Finally, we give the theme part of the paper, which is composed of the following two parts: first, under the framework of QCD factorization, B. 鈫捍n the standard model, this kind of decay process is pure annihilation process, and only the current-current operator contributes. It makes this kind of decay process a good place to study the decay of heavy meson annihilation. We will adopt two schemes to deal with the endpoint divergence in annihilation graph calculation: scheme I is a common QCD factorization method; Scheme II uses infrared finite gluon propagators and coupling constants. These two different schemes have been used to deal with the decay process of playing with dcs. In this paper, we study the decay process of Bc mesons. In the calculation, we use three different forms of Bc meson wave functions to compare. The results show that: 1. The branch ratio of this kind of decay process is very small, which is difficult to detect experimentally. In scheme II, the contribution of annihilation diagram is enhanced compared with scheme I when the infrared finite gluon propagator is used. But still less than the results given by pQCD. 鈫捪，

本文編號(hào)：1444239