奇特底夸克共振態之探尋

Search for bottomonium counterpart of X(3872) in Υ(1S)π+π− decay

陳柏勳(Po-Hsun Chen)

指導教授 ： 陳凱風

國立臺灣大學/理學院/物理研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.00814

摘要

本論文試圖於
Υ(1S)→μ+μ-π+π−衰變途徑中，尋找奇特魅夸克共振態X(3872)的底夸克對應共振態(Xb)。經由分析在質心能量8 TeV條件下，累計亮度20.65/fb的質子--質子對撞事件，在掃描的能量區間10-11 GeV/c^2內並未顯示出任何Xb的存在線索，對應的區域顯著性為2.6個標準差，全域顯著性為0.8個標準差。在95%信心水準下，可以給出在此特定衰變途徑下相對於Υ(2S)的散射截面比值上限為0.8--4.6%(隨Xb的靜止質量變動)。

關鍵字

奇特 ； 魅夸克共振態 ； 底夸克共振態

並列摘要

We report a search for a bottomonium counterpart of exotic charmonium state X(3872), denoted as Xb throughout this thesis. The target decay channel is Xb→Υ(1S)π+π−→μ+μ-π+π−. An integrated luminosity of 20.65/fb at proton-proton collision at sqrt{s}=8 TeV is analyzed. In the search phase space, |y_{Xb}| < 2.0, p_{T,Xb} > 13.5 GeV/c^2, and 10 < M_{Xb} < 11 GeV/c^2, the maximum local significance is 2.6 sigma, which equals to 0.8 sigma global significance. The upper limit at 95% confidence level is settled to be 0.8-4.6% (depend on the mass of Xb) as the cross section of Υ(1S)→Υ(1S)π+π−.

並列關鍵字

Quarkonium ； Charmonium ； Bottomonium ； X(3872) ； Upsilon(1S)

參考文獻

"Sjostrand, Torbjorn and Mrenna, Stephen and Skands, Peter Z.","PYTHIA 6.4 Physics and Manual","JHEP"

"Hoecker, Andreas and Speckmayer, Peter and Stelzer, Joerg and Therhaag, Jan and von Toerne, Eckhard and Voss, Helge","TMVA: Toolkit for Multivariate Data Analysis","PoS"

"Hou, Wei-Shu","Searching for the bottom counterparts of X(3872) and Y(4260) via pi+ pi- Upsilon","Phys.Rev. D"

"AlFiky, Mohammad T. and Gabbiani, Fabrizio and Petrov, Alexey A.","X(3872): Hadronic molecules in effective field theory","Phys.Lett. B"

"Ebert, D. and Faustov, R.N. and Galkin, V.O.","Masses of heavy tetraquarks in the relativistic quark model","Phys.Lett. B"