格點QCD測定強子結構及弱衰變(1/3)

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Project title/計畫英文名

Project Number/計畫編號

93-2112-M-002-016-

Translated Name/計畫中文名

格點QCD測定強子結構及弱衰變(1/3)

Project Principal Investigator/計畫主持人

TING-WAI CHIU

Funding Organization

Ministry of Science and Technology

Start date/計畫起

01-08-2004

Expected Completion/計畫迄

31-07-2005

摘要：在標準模型中，CKM 矩陣的酉一性 (unitarity) 給出了三角關係式。所以，任何實驗結果顯示這酉一性的違反均有可能被詮釋為"新物理"的跡象。目前已有許多實驗與理論上的努力來嘗試決定(或限定) CKM 矩陣元的值。然而，在可測量的物理量以及 CKM 矩陣元素之間的關係式中，牽涉到重夸克的部分，都深受其強作用在理論上的不確定性影響，例如在以及系統中的質量差與。目前，由第一原理出發以決定這些相關物理量的唯一可行方法就是格點量子色動力學。本研究計畫的其中一個主要目的就是使用具精確手則對稱的格點量子色動力學，來計算出 , ,以及B參數和之理論值。
近來，有些高能實驗已宣佈發現了奇異的強子態，這些強子也許可以視為5個或4個夸克態，例如及。值得注意的是，這些奇異強子的能譜寬度與它們的質量相較都很窄。這些新發現顯示了量子色動力學中有關強子的動力學方面，我們仍需要有更深入的了解。因此，以具精確手則對稱的格點量子色動力學為第一原理出發的計算，來決定這些奇異強子態是否真正存在於量子色動力學的能譜中，是相當重要的。此外，我們還要測定它們的衰變常數及其他相關物理量。這也是本研究計畫
Abstract: In the Standard Model, the unitarity of the CKM matrix gives the triangle relation. Thus any deviation from unitarity is interpreted as a signature of “new physics”. So far, there have been a lot of experimental and theoretical efforts devoted to determine (over-constrain) the elements of CKM matrix. However, relations between measurable quantities and CKM matrix elements involving heavy quarks are usually afficted with large hadronic uncertainties, such as mass difference and in the and systems. At present, the only viable way to determine the relevant quantities from the first principles is lattice QCD. One of the objectives of this project is to compute , , and the B-parameters and in the framework of lattice QCD with exact chiral symmetry.

Recently, several experimental groups announced the discoveries of exotic hadrons which may be regarded as 5- and 4-quark states, namely, and respectively. The remarkable feature of these exotic hadrons is their exceptionally narrow widths comparing with their masses. These new discoveries calls for a deeper understanding of the dynamics of QCD pertaining to the hadron physics. Thus it is important to see whether these hadronic states indeed exist in the spectrum of QCD, from the first principles calculations via lattice QCD with exact chiral symmetry. Further, we would like to determine their decay constants as well as other physical quantities. This is also one of the main objectives of this project.

Keyword(s)

格點量子色動力學
強子質量
衰變常數
CKM 矩陣元素
Lattice QCD
Hadron mass
Decay constants
CKM matrix elements

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格點QCD測定強子結構及弱衰變(1/3)

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