Evidence of rescattering effect in Pb–Pb collisions at the LHC through production of K<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mmultiscripts><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>892</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow><mml:none/><mml:mrow><mml:mn>0</mml:mn></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mo>⁎</mml:mo></mml:mrow></mml:mmultiscripts></mml:math> and ϕ(1020) mesons

Measurements of K$^*$(892)$^0$ and ϕ(1020) resonance production in Pb–Pb and pp collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with the ALICE detector at the Large Hadron Collider are reported. The resonances are measured at midrapidity (|y| &lt; 0.5) via their hadronic decay channels and the transverse momentum ($p_{\rm T}$) distributions are obtained for various collision centrality classes up to $p_{\rm T}$ = 20 GeV/c . The $p_{\rm T}$-integrated yield ratio K$^*$(892)$^0$/K in Pb–Pb collisions shows significant suppression relative to pp collisions and decreases towards more central collisions. In contrast, the ϕ(1020)/K ratio does not show any suppression. Furthermore, the measured K$^*$(892)$^0$/K ratio in central Pb–Pb collisions is significantly suppressed with respect to the expectations based on a thermal model calculation, while the ϕ(1020)/K ratio agrees with the model prediction. These measurements are an experimental demonstration of rescattering of K$^*$(892)$^0$ decay products in the hadronic phase of the collisions. The K$^*$(892)$^0$/K yield ratios in Pb–Pb and pp collisions are used to estimate the time duration between chemical and kinetic freeze-out, which is found to be ∼ 4–7 fm/c for central collisions. The $p_{\rm T}$-differential ratios of K$^*$(892)$^0$/K, ϕ(1020)/K, K$^*$(892)$^0$/ π , ϕ(1020)/π , p/K$^*$(892)$^0$ and p/ϕ(1020) are also presented for Pb–Pb and pp collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. These ratios show that the rescattering effect is predominantly a low-$p_{\rm T}$ phenomenon.

Hali tarjima qilinmagan