Spin alignment measurement of vector mesons produced in high energy collisions

doi:10.1142/S0217732321300263

	Spin alignment measurement of vector mesons produced in high energy collisions
	Mohanty, Bedangadas 1; Kundu, Sourav 2; Singha, Subhash 3; Singh, Ranbir 1
刊名	MODERN PHYSICS LETTERS A
	2021-12-21
卷号	36 期号:39 页码:23
关键词	Spin alignment vector meson rho(00) heavy-ion
ISSN号	0217-7323
DOI	10.1142/S0217732321300263
通讯作者	Mohanty, Bedangadas(bedanga@niser.ac.in)
英文摘要	This paper covers the recent experimental development on spin alignment measurements of K(0) and phi vector mesons in heavy-ion and pp collisions at RHIC and LHC energies. Measurements in e(+)e(-) collisions at LEP energies are also discussed. Spin alignment of vector mesons is studied by measuring the second diagonal element rho(00) of spin density matrix. The spin density matrix element rho(00) is obtained by measuring the angular distribution of vector meson decay daughter with respect to the quantization axis in vector meson rest frame. Measured rho(00) values for vector mesons are found to be larger than 1/3 at high momentum in e(+)e(-) collisions at LEP energies, suggesting the preferential production of vector meson with helicity zero state from the fragmentation process. The rho(00) values are found to be smaller than 1/3 (rho(00) = 1/3 implies no spin alignment) for K(0) and phi vector mesons at low transverse momentum in Pb{Pb collisions at root s(NN) = 2:76 TeV. These observations are qualitatively consistent with the expectation from models which attribute the spin alignment effect due to polarization of quarks in the presence of large initial angular momentum in noncentral heavy-ion collisions and its subsequent hadronization by the process of recombination. No significant spin alignment effect is observed for K-S(0) (spin = 0) in mid-central Pb-Pb collisions and for vector mesons in pp collisions. However, the preliminary results of rho(00) for phi mesons are larger than 1/3 at intermediate p(T) in Au-Au collisions at RHIC energies and can be attributed to the presence of phi meson field. Although there is evidence of spin alignment effect of vector mesons in heavy-ion collisions but the measured effect is surprisingly larger in context of hyperon polarization. Therefore, these results will trigger further theoretical study.
资助项目	J C Bose Fellowship from Department of Science of Technology, Government of India ; Research in Basic Sciences project from Department of Atomic Energy, Government of India ; Strategic Priority Research Program of Chinese Academy of Sciences[XDB34000000]
WOS关键词	GLOBAL POLARIZATION ; QUARK FRAGMENTATION ; DENSITY-MATRIX ; HADRONS ; LAMBDA
WOS研究方向	Astronomy & Astrophysics ; Physics
语种	英语
出版者	WORLD SCIENTIFIC PUBL CO PTE LTD
WOS记录号	WOS:000739878000004
资助机构	J C Bose Fellowship from Department of Science of Technology, Government of India ; Research in Basic Sciences project from Department of Atomic Energy, Government of India ; Strategic Priority Research Program of Chinese Academy of Sciences
内容类型	期刊论文
源URL	[http://119.78.100.186/handle/113462/142471]
专题	中国科学院近代物理研究所
通讯作者	Mohanty, Bedangadas
作者单位	1.Natl Inst Sci Educ & Res, Sch Phys Sci, HBNI, Jatni 752050, India 2.CERN, Expt Phys Dept, CH-1211 Geneva 23, Switzerland 3.Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Gansu, Peoples R China
推荐引用方式 GB/T 7714	Mohanty, Bedangadas,Kundu, Sourav,Singha, Subhash,et al. Spin alignment measurement of vector mesons produced in high energy collisions[J]. MODERN PHYSICS LETTERS A,2021,36(39):23.
APA	Mohanty, Bedangadas,Kundu, Sourav,Singha, Subhash,&Singh, Ranbir.(2021).Spin alignment measurement of vector mesons produced in high energy collisions.MODERN PHYSICS LETTERS A,36(39),23.
MLA	Mohanty, Bedangadas,et al."Spin alignment measurement of vector mesons produced in high energy collisions".MODERN PHYSICS LETTERS A 36.39(2021):23.