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Evidence of rescattering effect in Pb-Pb collisions at the LHC through production of $\rm{K}^{*}(892)^{0}$ and $\phi(1020)$ mesons

The collaboration
Phys.Lett. B802 (2020) 135225, 2020

Abstract
Measurements of K∗ (892) 0 and φ(1020)resonance production in Pb–Pb and pp collisions at √ sNN = 5.02 TeV with the ALICE detector at the Large Hadron Collider are reported. The resonances are measured at midrapidity (|y| < 0.5) via their hadronic decay channels and the transverse momentum (pT) distributions are obtained for various collision centrality classes up to pT = 20 GeV/c. The pT-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 pT-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 √ sNN = 5.02 TeV. These ratios show that the rescattering effect is predominantly a low-pT phenomenon.

• #### Table 1

Data from Figure 1 (left panel).

10.17182/hepdata.93150.v1/t1

$p_{\rm T}$-distributions of $\rm{K}^{*0}$ (average of particle and anti-particle) meson measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 2

Data from Figure 1 (left panel).

10.17182/hepdata.93150.v1/t2

$p_{\rm T}$-distributions of $\rm{K}^{*0}$ (average of particle and anti-particle) meson measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.

• #### Table 3

Data from Figure 1 (right panel).

10.17182/hepdata.93150.v1/t3

$p_{\rm T}$-distributions of $\phi$ meson measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 4

Data from Figure 1 (right panel).

10.17182/hepdata.93150.v1/t4

$p_{\rm T}$-distributions of $\phi$ meson measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.

• #### Table 5

Data from Figure 2.

10.17182/hepdata.93150.v1/t5

$p_{\rm T}$-integrated yield ratio of $\rm{K}^{*0}$ (average of particle and anti-particle) to K (average of particle and anti-particle) measured in...

• #### Table 6

Data from Figure 2.

10.17182/hepdata.93150.v1/t6

$p_{\rm T}$-integrated yield ratio of $\rm{K}^{*0}$ (average of particle and anti-particle) to K (average of particle and anti-particle) measured in...

• #### Table 7

Data from Figure 2.

10.17182/hepdata.93150.v1/t7

$p_{\rm T}$-integrated yield ratio of $\phi$ to K (average of particle and anti-particle) measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ =...

• #### Table 8

Data from Figure 2.

10.17182/hepdata.93150.v1/t8

$p_{\rm T}$-integrated yield ratio of $\phi$ to K (average of particle and anti-particle) measured in pp collisions at $\sqrt{s}$ =...

• #### Table 9

Data from Figure 4 (left panel).

10.17182/hepdata.93150.v1/t9

$p_{\rm T}$ differential ratio $(\rm{K}^{*0} + \bar{\rm{K}}^{*0}) / (\rm{K}^{+}+\rm{K}^{-})$ measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 10

Data from Figure 4 (left panel).

10.17182/hepdata.93150.v1/t10

$p_{\rm T}$ differential ratio $(\rm{K}^{*0} + \bar{\rm{K}}^{*0}) / (\rm{K}^{+}+\rm{K}^{-})$ measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.

• #### Table 11

Data from Figure 4 (right panel).

10.17182/hepdata.93150.v1/t11

$p_{\rm T}$ differential ratio $(2\phi) / (\rm{K}^{+}+\rm{K}^{-})$ measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 12

Data from Figure 4 (right panel).

10.17182/hepdata.93150.v1/t12

$p_{\rm T}$ differential ratio $(2\phi) / (\rm{K}^{+}+\rm{K}^{-})$ measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.

• #### Table 13

Data from Figure 5 (left panel).

10.17182/hepdata.93150.v1/t13

$p_{\rm T}$ differential ratio $(\rm{K}^{*0} + \bar{\rm{K}}^{*0}) / (\pi^{+}+\pi^{-})$ measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 14

Data from Figure 5 (left panel).

10.17182/hepdata.93150.v1/t14

$p_{\rm T}$ differential ratio $(\rm{K}^{*0} + \bar{\rm{K}}^{*0}) / (\pi^{+}+\pi^{-})$ measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.

• #### Table 15

Data from Figure 5 (right panel).

10.17182/hepdata.93150.v1/t15

$p_{\rm T}$ differential ratio $(2\phi) / (\pi^{+}+\pi^{-})$ measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 16

Data from Figure 5 (right panel).

10.17182/hepdata.93150.v1/t16

$p_{\rm T}$ differential ratio $(2\phi) / (\pi^{+}+\pi^{-})$ measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.

• #### Table 17

Data from Figure 6 (left panel).

10.17182/hepdata.93150.v1/t17

$p_{\rm T}$ differential ratio $(\rm{p} + \bar{\rm p}) / (\rm{K}^{*0} + \bar{\rm{K}}^{*0})$ measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02...

• #### Table 18

Data from Figure 6 (left panel).

10.17182/hepdata.93150.v1/t18

$p_{\rm T}$ differential ratio $(\rm{p} + \bar{\rm p}) / (\rm{K}^{*0} + \bar{\rm{K}}^{*0})$ measured in pp collisions at $\sqrt{s}$ = 5.02...

• #### Table 19

Data from Figure 6 (right panel).

10.17182/hepdata.93150.v1/t19

$p_{\rm T}$ differential ratio $(\rm{p} + \bar{\rm p}) / (2\phi)$ measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.

• #### Table 20

Data from Figure 6 (right panel).

10.17182/hepdata.93150.v1/t20

$p_{\rm T}$ differential ratio $(\rm{p} + \bar{\rm p}) / (2\phi)$ measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.