Evidence of Spin-Orbital Angular Momentum Interactions in Relativistic Heavy-Ion Collisions

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Evidence of Spin-Orbital Angular Momentum Interactions in Relativistic Heavy-Ion Collisions. / ALICE Collaboration.

In: Physical Review Letters, Vol. 125, No. 1, 012301, 30.06.2020.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{f32d4cb847e64b0ba1223717a476896c,

title = "Evidence of Spin-Orbital Angular Momentum Interactions in Relativistic Heavy-Ion Collisions",

abstract = "The first evidence of spin alignment of vector mesons (K∗0 and φ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ00 is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a center-of-mass energy (sNN) of 2.76 TeV with the ALICE detector. ρ00 values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum (pT<2 GeV/c) for K∗0 and φ at a level of 3σ and 2σ, respectively. No significant spin alignment is observed for the KS0 meson (spin=0) in Pb-Pb collisions and for the vector mesons in pp collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination. ",

keywords = "GLOBAL POLARIZATION, ALIGNMENT, MESONS, LAMBDA, QCD",

author = "{ALICE Collaboration} and S. Acharya and D. Adamov{\'a} and A. Adler and J. Adolfsson and Aggarwal, {M. M.} and {Aglieri Rinella}, G. and M. Agnello and N. Agrawal and Z. Ahammed and S. Ahmad and Ahn, {S. U.} and A. Akindinov and M. Al-Turany and Alam, {S. N.} and Albuquerque, {D. S.D.} and D. Aleksandrov and B. Alessandro and Alfanda, {H. M.} and {Alfaro Molina}, R. and B. Ali and Y. Ali and A. Alici and A. Alkin and J. Alme and T. Alt and L. Altenkamper and I. Altsybeev and Anaam, {M. N.} and C. Andrei and D. Andreou and Andrews, {H. A.} and A. Andronic and M. Angeletti and V. Anguelov and C. Anson and T. Anti{\v c}i{\'c} and F. Antinori and P. Antonioli and R. Anwar and N. Apadula and L. Aphecetche and H. Appelsh{\"a}user and A. Erokhin and G. Feofilov and V. Kovalenko and T. Lazareva and D. Nesterov and V. Vechernin and A. Zarochentsev and V. Zherebchevskii",

note = "Publisher Copyright: {\textcopyright} 2020 CERN.",

year = "2020",

month = jun,

day = "30",

doi = "10.1103/PhysRevLett.125.012301",

language = "English",

volume = "125",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "1",

}

RIS

TY - JOUR

T1 - Evidence of Spin-Orbital Angular Momentum Interactions in Relativistic Heavy-Ion Collisions

AU - ALICE Collaboration

AU - Acharya, S.

AU - Adamová, D.

AU - Adler, A.

AU - Adolfsson, J.

AU - Aggarwal, M. M.

AU - Aglieri Rinella, G.

AU - Agnello, M.

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahmad, S.

AU - Ahn, S. U.

AU - Akindinov, A.

AU - Al-Turany, M.

AU - Alam, S. N.

AU - Albuquerque, D. S.D.

AU - Aleksandrov, D.

AU - Alessandro, B.

AU - Alfanda, H. M.

AU - Alfaro Molina, R.

AU - Ali, B.

AU - Ali, Y.

AU - Alici, A.

AU - Alkin, A.

AU - Alme, J.

AU - Alt, T.

AU - Altenkamper, L.

AU - Altsybeev, I.

AU - Anaam, M. N.

AU - Andrei, C.

AU - Andreou, D.

AU - Andrews, H. A.

AU - Andronic, A.

AU - Angeletti, M.

AU - Anguelov, V.

AU - Anson, C.

AU - Antičić, T.

AU - Antinori, F.

AU - Antonioli, P.

AU - Anwar, R.

AU - Apadula, N.

AU - Aphecetche, L.

AU - Appelshäuser, H.

AU - Erokhin, A.

AU - Feofilov, G.

AU - Kovalenko, V.

AU - Lazareva, T.

AU - Nesterov, D.

AU - Vechernin, V.

AU - Zarochentsev, A.

AU - Zherebchevskii, V.

PY - 2020/6/30

Y1 - 2020/6/30

N2 - The first evidence of spin alignment of vector mesons (K∗0 and φ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ00 is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a center-of-mass energy (sNN) of 2.76 TeV with the ALICE detector. ρ00 values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum (pT<2 GeV/c) for K∗0 and φ at a level of 3σ and 2σ, respectively. No significant spin alignment is observed for the KS0 meson (spin=0) in Pb-Pb collisions and for the vector mesons in pp collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination.

AB - The first evidence of spin alignment of vector mesons (K∗0 and φ) in heavy-ion collisions at the Large Hadron Collider (LHC) is reported. The spin density matrix element ρ00 is measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a center-of-mass energy (sNN) of 2.76 TeV with the ALICE detector. ρ00 values are found to be less than 1/3 (1/3 implies no spin alignment) at low transverse momentum (pT<2 GeV/c) for K∗0 and φ at a level of 3σ and 2σ, respectively. No significant spin alignment is observed for the KS0 meson (spin=0) in Pb-Pb collisions and for the vector mesons in pp collisions. The measured spin alignment is unexpectedly large but qualitatively consistent with the expectation from models which attribute it to a polarization of quarks in the presence of angular momentum in heavy-ion collisions and a subsequent hadronization by the process of recombination.

KW - GLOBAL POLARIZATION

KW - ALIGNMENT

KW - MESONS

KW - LAMBDA

KW - QCD

UR - http://www.scopus.com/inward/record.url?scp=85087940641&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.125.012301

DO - 10.1103/PhysRevLett.125.012301

M3 - Article

C2 - 32678650

AN - SCOPUS:85087940641

VL - 125

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 1

M1 - 012301

ER -

ID: 61994415