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

Autori
Acharya, S. ; ... ; Antičić, Tome ; ... ; Erhardt, Filip ; ... ; Gotovac, Sven ; ... ; Jerčić, Marko ; ... ; Lončar, Petra ; ... ; Mudnić, Eugen ; ... ; Planinić, Mirko ; ... ; Poljak, Nikola ; ... ; Simatović, Goran ; ... ; Utrobičić, Antonija ; ... ; Vicković, Linda ; ... ; Zurlo, N.

Kolaboracija
ALICE Collaboration

Izvornik
Physical review letters (0031-9007) 125 (2020), 1; 012301, 12

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
spin-orbital angular momentum interactions ; heavy-ion collisions

Sažetak
The first evidence of spin alignment of vector mesons (K0 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 K0 and ϕ at a level of 3σ and 2σ, respectively. No significant spin alignment is observed for the K^0_S 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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA