First results of $K^{*}(892)^{\pm}$ production in $pp$ collisions at $\sqrt{s} = 13$ TeV with ALICE at LHC.

Garg K. per la Collaborazione ALICE
  Giovedì 14/09   09:00 - 11:30   Aula A208   I - Fisica nucleare e subnucleare
The study of hadronic resonances plays an important role both in $pp$ and in heavy-ion collisions as it provides information about strangeness production and the hadronic phase of the system. Since the lifetimes of short-lived resonances are comparable with the lifetime of the fireball formed in heavy-ion collisions, regeneration and rescattering effects can modify the measured yield especially at low transverse momentum. The ratio of the yields of the resonances to that of longer-lived particles can therefore be used to estimate the time interval between the chemical and kinetic freeze-out. Measurements in $pp$ collisions constitute a baseline for studies in heavy-ion collisions and provide constraints for tuning QCD-inspired event generators. In particular, the resonance $K^{*}(892)^{\pm}$ is important because of its very short lifetime ($\sim 4$ fm/$c$). In this contribution, we will report the first results at LHC energies for $K^{*}(892)^{\pm}$ resonance in $pp$ collisions at $\sqrt{s_{NN}} = 13$ TeV. $K^{*}(892)^{\pm}$ has been measured at mid-rapidity via its hadronic decay channel $K^{*}(892)^{\pm}\rightarrow {K}^{0}_{S} + \pi^{\pm}$, with the ALICE detector. In particular, the transverse momentum ($p_{T}$) spectrum, integrated yields and $\langle p_{T}\rangle$ will be presented and compared with model predictions. $K^{*}(892)^{\pm}$ results will also be compared to $K^{*}(892)^{0}$ obtained by ALICE at the same collision energy.