K*(892)± resonance production in Pb-Pb collisions at sNN =5.02 TeV

Abstract

The production of K * ( 892 ) ± meson resonance is measured at midrapidity ( | y | 0.5 ) in Pb − Pb collisions at s N N = 5.02 TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel K * ( 892 ) ± → K S 0 π ± . The transverse momentum distributions are obtained for various centrality intervals in the p T range of 0.4 − 16 GeV / c . Measurements of integrated yields, mean transverse momenta, and particle yield ratios are reported and found to be consistent with previous ALICE measurements for K * ( 892 ) 0 within uncertainties. The p T -integrated yield ratio 2 K * ( 892 ) ± / ( K + + K − ) in central Pb − Pb collisions shows a significant suppression at a level of 9.3 σ relative to p p collisions. Thermal model calculations result in an overprediction of the particle yield ratio. Although both hadron resonance gas in partial chemical equilibrium (HRG-PCE) and + simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas + simulations tend to overpredict the particle yield ratio. These observations, along with the kinetic freeze-out temperatures extracted from the yields measured for light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which decreases with increasing collision centrality percentile. The p T -differential yield ratios 2 K * ( 892 ) ± / ( K + + K − ) and 2 K * ( 892 ) ± / ( π + + π − ) are presented and compared with measurements in pp collisions at s = 5.02 TeV. Both particle ratios are found to be suppressed by up to a factor of five at p T 2.0 GeV / c in central Pb − Pb collisions and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor ( R AA ) shows a smooth evolution with centrality and is found to be below unity at p T > 8 GeV / c , consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium. ©2024 CERN, for the ALICE Collaboration 2024 CERN