Observation of (Formula presented) Hyperon Local Polarization in (Formula presented)-Pb Collisions at (Formula presented)


Hayrapetyan A., Tumasyan A., Adam W., Andrejkovic J., Benato L., Bergauer T., ...Daha Fazla

Physical Review Letters, cilt.135, sa.13, 2025 (SCI-Expanded, Scopus) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 135 Sayı: 13
  • Basım Tarihi: 2025
  • Doi Numarası: 10.1103/6ywq-gm61
  • Dergi Adı: Physical Review Letters
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC, MathSciNet, zbMATH, DIALNET, Nature Index
  • Erzincan Binali Yıldırım Üniversitesi Adresli: Evet

Özet

The polarization of the (Formula presented) and (Formula presented) hyperons along the beam direction has been measured in proton-lead ((Formula presented)) collisions at a center-of-mass energy per nucleon pair of 8.16 TeV. The data were obtained with the CMS detector at the LHC and correspond to an integrated luminosity of (Formula presented). A significant azimuthal dependence of the hyperon polarization, characterized by the second-order Fourier sine coefficient (Formula presented), is observed. The (Formula presented) values decrease as a function of charged particle multiplicity, but increase with transverse momentum. A hydrodynamic model that describes the observed (Formula presented) values in nucleus-nucleus collisions by introducing vorticity effects does not reproduce either the sign or the magnitude of the (Formula presented) results. These observations pose a challenge to the current theoretical implementation of spin polarization in heavy ion collisions and offer new insights into the origin of spin polarization in hadronic collisions at LHC energies.