Recent results from PHENIX on double helicity asymmetry ($A_{LL}$) measurement at center of mass energy of $\sqrt{s}$ = 510 GeV

29 Apr 2015, 14:00
25m
BALLROOM EAST ()

BALLROOM EAST

WG6 Spin Physics WG6 Spin Physics

Speaker

Hari Guragain (PHENIX Collaboration)

Description

One of the major objectives of the RHIC spin program at BNL is the measurement of the gluon helicity contribution, $\Delta G$, to the proton spin via measuring the double longitudinal spin asymmetry ($A_{LL}$) in various channels. In PHENIX (Pioneering High Energy Nuclear Interaction eXperiment) the $A_{LL}$ in $\pi^{0}$, $\eta$, $J/\psi$ etc. are measured in wide rapidity range. In this talk, $A_{LL}$ in $\pi^{0}$ production in central rapidity and $J/\psi$ production in forward rapidity will be discussed. The $\pi^{0}$ is reconstructed through its diphoton decay channel within the rapidity range of $\left| \eta \right|$ $<$ 0.35 and azimuthal angle of $180\,^{\circ}$. Similarly, $J/\psi$ is reconstructed via dimuon decay channel within the rapidity range of 1.2 $<$ $\left| \eta \right|$ $<$ 2.2. Preliminary results for $A_{LL}$ in $\pi^{0}$ and $J/\psi$ production from the data collected in the year 2013 at center of mass energy ($\sqrt{s}$) = 510 GeV will be presented. Also, their impact on $\Delta G$ constraint will be discussed. In year 2013, the total integrated luminosity was 150 $pb^{-1}$ which is almost ten times the total luminosity recorded in the year 2009 at $\sqrt{s}$ = 200 GeV. Due to increase in the center of mass energy and integrated luminosity, the new measurements can cover the Bjorken x range down to 0.01 for $\pi^{0}$ and 0.002 for $J/\psi$.

Primary author

Hari Guragain (PHENIX Collaboration)

Presentation Materials