Quark Polarization in Relativistic Heavy Ion Collisions

Presentation on theme: "Quark Polarization in Relativistic Heavy Ion Collisions"— Presentation transcript:

1 Quark Polarization in Relativistic Heavy Ion Collisions
山东大学博士论文答辩 高能重离子碰撞中的夸克极化现象研究 Quark Polarization in Relativistic Heavy Ion Collisions 答辩人: 高建华 导 师 : 梁作堂 王新年 山东大学物理学院 2008年11月28日 2019/2/22 山东大学物理学院 高建华

2 Outline Introduction Longitudinal momentum flow
Global polarization of light quark Global polarization of heavy quark Polarization induced by jets in QGP Summary and outlook 2019/2/22 山东大学物理学院 高建华

3 Introduction 2019/2/22 山东大学物理学院 高建华

4 Hyperon polarization in unpolarized p+p/A H+X
Spin effects usually provide us with useful information on reaction mechanism and often surprises. p p/A production plane 2019/2/22 山东大学物理学院 高建华

5 Non-central A+A collisions
py px x z x y py Reaction plane : px 2019/2/22 山东大学物理学院 高建华

6 Orbital angular momentum in non-central A+A
Y Hard sphere Z. T. Liang & X. N. Wang, Phys. Rev. Lett. 94, (2005) 2019/2/22 山东大学物理学院 高建华

7 Global polarization in non-central A+A
Static potential model ( Debye mass) “Small angle approximation ( )” A New Picture of QGP in A+A Z. T. Liang & X. N. Wang, PRL 94, (2005); PLB629, 20 (2005) 2019/2/22 山东大学物理学院 高建华

8 Contents of My Thesis Longitudinal momentum flow distribution
Woods saxon + Landau fireball Hard sphere + Landau fireball Bjorken scaling scenario Calculation of global polarization Static potential model QCD in finite temperature Another interesting application Polarization induced by jets in QGP 2019/2/22 山东大学物理学院 高建华

9 Longitudinal flow distribution
2019/2/22 山东大学物理学院 高建华

10 Huge orbital angular momentum in non-central A+A
Nuclear distribution function : Hard Sphere Woods Saxon 2019/2/22 山东大学物理学院 高建华

11 Landau fireball VS Bjorken scaling
Two limit scenarios Landau fireball Bjorken scaling z x z x is the same for fixed x is the same for fixed x 2019/2/22 山东大学物理学院 高建华

12 Longitudinal momentum flow in Landau fireball model
longitudinal momentum per produced parton c(s): number of partons per NN collision 2019/2/22 山东大学物理学院 高建华

13 Local orbital angular momentum in Landau fireball model
2019/2/22 山东大学物理学院 高建华

14 Rapidity shear in Bjorken scaling model
z x All results from HIJING 2019/2/22 山东大学物理学院 高建华

15 Conclusions for different scenarios
Woods Saxon distribution lead to almost the same local angular momentum distribution as Hard sphere. Bjorken scaling scenario can also lead to local angular momentum distribution, but is much small than Landau fireball scenario. 2019/2/22 山东大学物理学院 高建华

16 Global polarization of light quark
2019/2/22 山东大学物理学院 高建华

17 Quark scattering with fixed impact parameter
Scattering amplitude in momentum space Fourier transformation from to Differential cross section w.r.t. the impact parameter average over the preferred directions z x y Quantization direction could be different for initial and final states Quark polarization : 2019/2/22 山东大学物理学院 高建华

18 Calculation with HTL Gluon Propagator
Scattering amplitude Cross section in impact parameter space Where : In CM frame Nonperturbative magnetic mass: Debye screening mass: 2019/2/22 山东大学物理学院 高建华

19 HTL vs Static Potential Model
z x y For light quark where p >> m HTL at small angle approximation Static potential model at small angle approximation 2019/2/22 山东大学物理学院 高建华

20 Analytic result for light quark polarization
where :CM energy 2019/2/22 山东大学物理学院 高建华

21 Analytic result for light quark polarization
In the limit In the limit In the weak coupling limit: Drop the magnetic contribution: 2019/2/22 山东大学物理学院 高建华

22 Numerical results for polarization of light quark
LHC The temperature of heat bath RHIC The CM energy of scattering quark RHIC : Landau fireball model LHC : Bjorken scaling scenario RHIC : 2019/2/22 山东大学物理学院 高建华

23 Electric and Magnetic contribution
full HTL HTL with only electric contribution The temperature of heat bath The CM energy of scattering quarks Magnetic screening mass 2019/2/22 山东大学物理学院 高建华

24 Global polarization of light quark
full HTL HTL with small angle approximation Static potential model with small angle approximation 2019/2/22 山东大学物理学院 高建华

25 How to measure such polarization?
Hyperon polarization quark polarization hadron polarization Vector meson spin alignment (Z. T. Liang & X. N. Wang, PRL 94, (2005); PLB629, 20 (2005)) Hyperon weak decay HB+M Vector meson strong decay VM1+M2 spin density matrix: 2019/2/22 山东大学物理学院 高建华

26 Experimental results : hyperon polarization
By STAR Collaboration Phys.Rev.C76:024915,2007 2019/2/22 山东大学物理学院 高建华

27 Experimental results : vector meson spin alignment
STAR Collaboration Phys.Rev.C77:061902,2008 2019/2/22 山东大学物理学院 高建华

28 Global polarization of heavy quark
2019/2/22 山东大学物理学院 高建华

29 Calculation for heavy quark polarization
For heavy quark where m>>p (heavy quark) (light quark) HTL at small angle approximation Static potential model 2019/2/22 山东大学物理学院 高建华

30 Analytic results for heavy quark polarization
2019/2/22 山东大学物理学院 高建华

31 Numerical results for heavy quark polarization
Static potential model :The mass of heavy quark : The temperature of heat bath :The CM momentum of scattering quarks 2019/2/22 山东大学物理学院 高建华

32 Polarization induced by jets
2019/2/22 山东大学物理学院 高建华

33 Polarization induced by jets in QGP
Polarization direction of thermal quark relative to jet axis 2019/2/22 山东大学物理学院 高建华

34 Polarization induced by jets in QGP
Reaction rate in momentum space Reaction rate in impact parameter space : fermionic or bosonic distribution function 2019/2/22 山东大学物理学院 高建华

35 Polarization induced by jets in QGP
The energy of jet The temperature of heat bath 2019/2/22 山东大学物理学院 高建华

36 Summary In non-central AA collisions, there exists local orbital angular momentum, which can lead to quark polarization. In Landau fireball model, quark polarization at RHIC is very small, but can be up to 25% at LHC. The polarization in Bjorken scaling scenario is much less than that in Landau fireball model. Heavy quark’s polarization is dependent of quark’s mass, and decrease with increasing mass of heavy quark. In QGP, jet can induce thermal quark’s polarization around it. Such polarization approaches to a constant in high energy limit. 2019/2/22 山东大学物理学院 高建华

37 Outlook Only single collision is considered, it will be interesting to calculate the effects from multiple collisions. Only the simplest flow distribution is considered. More realistic distribution should be taken into account further. The final hadron interaction is not taken into account yet , Such effect should and could be considered. This work is underway. Improve the formalism of differential cross section at fixed impact parameter , especially in low energy. 2019/2/22 山东大学物理学院 高建华

38 Thanks a lot 2019/2/22 山东大学物理学院 高建华