Speaker
Zhiguo He
(Hamburg University)
Description
We analyze the first measurement of $\eta_c$
production, performed by the LHCb Collaboration, in
the nonrelativistic-QCD (NRQCD) factorization framework
at next-to-leading order (NLO) in the
strong-coupling constant $\alpha_s$ and the relative velocity v
of the bound quarks including the feeddown
from $h_c$ mesons. Converting the long-distance matrix elements (LDM
Es) extracted by various groups from $J/\psi$
yield and polarization data to the $\eta_c$
case using heavy-quark spin symmetry, we find that
the resulting NLO NRQCD predictions greatly overshoot the L
HCb data, while the color-singlet model provides an excellent description
Primary author
Zhiguo He
(Hamburg University)
