Angular decay coefficients of J/ψ mesons at forward rapidity from p+p collisions at s=510 GeV

Le résumé fourni par la source

We report the first measurement of the full angular distribution for inclusive $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decays in $p+p$ collisions at $\sqrt{s}=510\text{ }\text{ }\mathrm{GeV}$. The measurements are made for $J/\ensuremath{\psi}$ transverse momentum $2<{p}_{T}<10\text{ }\text{ }\mathrm{GeV}/c$ and rapidity $1.2<y<2.2$ in the Helicity, Collins-Soper, and Gottfried-Jackson reference frames. In all frames the polar coefficient ${\ensuremath{\lambda}}_{\ensuremath{\theta}}$ is strongly negative at low ${p}_{T}$ and becomes close to zero at high ${p}_{T}$, while the azimuthal coefficient ${\ensuremath{\lambda}}_{\ensuremath{\phi}}$ is close to zero at low ${p}_{T}$, and becomes slightly negative at higher ${p}_{T}$. The frame-independent coefficient $\stackrel{\texttildelow{}}{\ensuremath{\lambda}}$ is strongly negative at all ${p}_{T}$ in all frames. The data are compared to the theoretical predictions provided by nonrelativistic quantum chromodynamics models.

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