Elliptic flow of $\varphi$-meson at intermediate $p_T$: Influence of mass versus quark number

Abstract

We have studied elliptic flow ($v_2$) of $\varphi$-mesons in the framework of a multi phase transport (AMPT) model at LHC energy. In the realms of AMPT model we observe $\varphi$-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 $\varphi$-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 $\varphi$-mesons decouple from the hadronic medium before additional radial flow is build-up in the hadronic phase, similar pattern in $\varphi$-meson and proton $v_2$ may not be due to radial flow alone. Our study reveals that models incorporating $\varphi$-meson production from $K\bar{K}$ fusion in the hadronic rescattering phase also predict a comparable magnitude of $\varphi$-meson and proton $v_2$ particularly in the intermediate region of $p_T$. Whereas, $v_2$ of $\varphi$-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 $\varphi$-meson $v_2$. We have also observed a violation of hydrodynamical mass ordering between proton and $\varphi$-meson $v_2$ further supporting that $\varphi$-mesons are negligibly affected by the collective radial flow in the hadronic phase due to the small in-medium hadronic interaction cross sections.

Comments: 6 pages, 6 figures