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　論文類型：學(xué)位論文

【摘要】：重味物理是檢驗標(biāo)準(zhǔn)模型、探索CP破壞起源和尋找新物理的重要場所。LHC的運行,預(yù)計每年將產(chǎn)生5×1010 Bc事例數(shù)。同時,在Belle和BaBar已經(jīng)收集了超過108 T介子的實驗數(shù)據(jù)；而在LHCb上,每.f6-1積分亮度下預(yù)計會產(chǎn)生1011巧事例數(shù)；即將運行的SuperKEKB上也將會產(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所。在本文中我們將采用QCD因子化方法來對Bc介子和T介子的一些弱衰變過程進行研究和分析。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等。其次,我們介紹了幾種常用的計算強子矩陣元的方法,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B→PP, PV的兩體非輕無粲過程進行分析。在標(biāo)準(zhǔn)模型下,這一類衰變過程是純湮滅過程,且只有流-流算符有貢獻,使得這類衰變過程成為研究重介子湮滅衰變的一個很好的場所。在本文中,我們將采用兩種方案來處理湮滅圖計算中的端點發(fā)散問題：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的衰變過程,在這里我們用于研究Bc介子的衰變過程。在計算中,我們采用了三種不同形式的Bc介子波函數(shù)進行比較。結(jié)果表明：在方案Ⅰ下,該類衰變過程的分支比結(jié)果很小,較難在實驗上被探測到。在方案Ⅱ下,當(dāng)采用紅外有限的膠子傳播子時,湮滅圖的貢獻相對于方案Ⅰ來說得到了增強,但依然小于pQCD給出的計算結(jié)果。在我們的計算中,Bc-→π-ω過程有著最大的衰變分支比Br(Bc-→π-ω)=12.8×10-8,這個衰變過程很可能在LHC或即將運行的SuperKEKB上被探測到。接著,我們在QCD因子化方案下研究了T(nS)→BcM的衰變過程,并用非相對論波函數(shù)來計算T到介子的躍遷形狀因子。唯象上,T(nS)→BcM的弱衰變過程僅有流-流算符的貢獻,并且是被CKM矩陣元vd,增強的,因此這類衰變過程在T介子的弱衰變中有著相對較大的分支比。結(jié)果表明：在T(nS)→BcM這類衰變中(M=π,ρ,K和K*),T(nS)→Bcp的衰變過程有著相對較大的分支比結(jié)果,大約在O(10-10),應(yīng)該最先在實驗上被探測到。
[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：1444239