王伟 上海交通大学 2015 怀柔 强子物理与核物理前沿研讨会

Presentation on theme: "王伟 上海交通大学 2015 怀柔 强子物理与核物理前沿研讨会"— Presentation transcript:

1 王伟 上海交通大学 2015 怀柔 强子物理与核物理前沿研讨会
Production of Heavy Meson Molecules at LHC  王伟 上海交通大学 2015 怀柔 强子物理与核物理前沿研讨会

2 Content Motivation for Hadron Exotics Heavy Meson Molecule
Production at the LHC Summary

3 Many Excellent Talks in this workshop!
强子是由什么构成？ 经典强子： 介子：夸克和反夸克 重子：三个夸克 超出夸克模型的强子是否存在？ Many Excellent Talks in this workshop!

4

5 Zc+= Zc(3900) is Exotic! ZcJ/ψp Zc state contains a cc quark pair
_ ZcJ/ψp Zc state contains a cc quark pair charge = ± 1  Zc must contain additional light quarks “minimal” quark configuration : Four-quark states! Zc+=

6 Zc(3900) is not alone Y(3940) Z(4430) X(3872) Yb(10890) Zc(3900)
Zb(10610) Zb(10650) Zc(4020) Y(4260) X(3940) X(4360) Y(4660) Y(4350) Ds(2460) Ds(2137)

7 What is the nature?

8 重介子分子态候选者 奇异粒子 组分 X(3872) DD* Xb BB* Zc(3900) Zc(4020) D*D* Zb(10610)
Ds(2317) DK JPC 质量(GeV) 1++ ? 1+- 3.8887 4.0239 0+ 2.3177 PDG:CPC38, (2014)

9 How to study exotics? Effective field theory is an approximation to an underlying physical theory. EFT includes the appropriate degrees of freedom to describe physical phenomena occurring at a chosen length scale or energy scale: scale separation

10 At Low Energy, Quark-hadron duality:
QCD degrees of freedom are equivalent to hadron degrees of freedom. Chiral perturbation theory!

11 ChiPT limited to low energies

12 mQ →∞时， Q →0 ，重轻夸克之间的自旋相互作用是压低的 轻夸克对于SQ不敏感，不依赖于SQz=1/2或者SQz= –1/2
重夸克对称性 mQ →∞时， Q →0 ，重轻夸克之间的自旋相互作用是压低的 轻夸克对于SQ不敏感，不依赖于SQz=1/2或者SQz= –1/2 轻夸克在与以下四种重夸克态组成的强子中是一样的： b(↑), b(↓); c(↑), c(↓) 如果轻夸克系统的角动量是Jl，与重夸克组成的强子角动量是 J=|Jl±1/2| 构造一个重强子有效理论

13 Heavy Meson Chiral Perturbation Theory
Heavy Meson: DD*, BB* Heavy Meson+a Pseudo-Scalar: DK

14 Mass pole corresponds to a resonance structure
什么是Hadron Molecule? Summing All order contributions: 1-GV＝0 s=s0 Mass pole corresponds to a resonance structure  Hadron Molecule

15 电子对撞机和强子对撞机 电子对撞机 强子对撞机 背景干净 末态包含很多强子 能量较低(<11GeV) 不能产生大质量粒子 能量高
可以产生较大质量的粒子 产生矢量粒子1— 其它粒子需要从1—衰变末态产生 可以产生任意量子数的粒子

16 Γ+ ΓGV + ΓGVGV+…. = Γ /(1-GV) Γ is tree-level amplitude.
Production at LHC Γ+ ΓGV + ΓGVGV+…. = Γ /(1-GV) Γ is tree-level amplitude. 1-GV＝0

17 Monte Carlo Event Generators
Herwig/Pythia: simulate production rates of constituents, Γ For charmonium/bottomonium-like states, heavy quarks move together, and a third parton is requested. 2->3 process: use Madgraph Use Rivet to analyze hadronic events

18 F.K. Guo, U.G. Meissner, WW, Z.Yang 1403.4032
X(3872): EFT vs data F.K. Guo, U.G. Meissner, WW, Z.Yang Histograms: MC event generators Curves: fit according to EFT.

19 Counterpart of X(3872): JPC=1++; BB* molecule state
Xb Counterpart of X(3872): JPC=1++; BB* molecule state Very heavy (11 GeV): difficult to directly produce at electron-positron collider Belle Phys.Rev.Lett.113(2014)142001 CMS made an attempt: Phys.Lett. B727 (2013) 57-76 ATLAS:Phys.Lett.B740(2015)199

20 Xb decays into Υπ+π- violates isospin  tiny BR.
F.K. Guo U.G. Meissner WW Xb decays into Υπ+π- violates isospin  tiny BR. One may look at Υγ, Υπ+π-π0,χbπ+π-. Radiative decays width are about 1 keV G.Li WW

21 Thank you for your attention!
Summary Hadron Exotic is a fast-developing branch. EFT can be used to explore hadron molecules. We have studied the production of exotic states at the LHC: a) X-sections; b) decay modes More:Heavy Ion Collision? HZF? CEPC? Thank you for your attention!