Elliptic flow of ϕ mesons at intermediate pT : Influence of mass versus quark number

Abstract

We have studied elliptic flow ($v_{2}$) of $\phi$-mesons in the framework of a multi phase transport (AMPT) model at LHC energy. In the realms of AMPT model we observe $\phi$-mesons at intermediate transverse momentum ($p_{T}$) deviate from the previously observed (at RHIC) particle type grouping of $v_{2}$ according to the number of quark content i.e, baryons and mesons. Recent results from the ALICE Collaboration have shown that $\phi$-meson and proton $v_{2}$ has a similar trend, possibly indicating that particle type grouping might be due to the mass of the particles and not the quark content. A stronger radial boost at LHC compared to RHIC seems to offer a consistent explanation to such observation. However, recalling that $\phi$-mesons decouple from the hadronic medium before additional radial flow is build-up in the hadronic phase, similar pattern in $\phi$-meson and proton $v_{2}$ may not be due to radial flow alone. Our study reveals that models incorporating $\phi$-meson production from $K\bar{K}$ fusion in the hadronic rescattering phase also predict a comparable magnitude of $\phi$-meson and proton $v_{2}$ particularly in the intermediate region of $p_{T}$. Whereas, $v_{2}$ of $\phi$-mesons created in the partonic phase is in agreement with quark-coalescence motivated baryon-meson grouping of hadron $v_{2}$. This observation seems to provide a plausible alternative interpretation for the apparent mass-like behaviour of $\phi$-meson $v_{2}$. We have also observed a violation of hydrodynamical mass ordering between proton and $\phi$-meson $v_{2}$ further supporting that $\phi$-mesons are negligibly affected by the collective radial flow in the hadronic phase due to the small in-medium hadronic interaction cross sections.