by
Hiroshi Yokoya(Korea Institute of Advanced Study)
→
Europe/Berlin
313 (MPI Meeting rooms)
313
MPI Meeting rooms
Description
We study $gg \rightarrow \gamma \gamma$ amplitudes by including $t \bar{t}$ bound-state effects near their mass threshold.
In terms of the non-relativistic expansion of the amplitude, the LO contribution is an energy-independent term in the one-loop amplitude,
and a part of the NLO contribution is described by the non-relativistic Green function.
We find that due to the interference of these terms, the diphoton mass spectrum shows a characteristic dip-and-bump shape near the threshold.
In addition, the position of the dip and the bump is determined by the \textit{1S-mass} of the $t \bar{t}$ resonance which is well predicted in terms of the short-distance mass of top-quark in \textbf{NRQCD}.
Thanks to the simple and clean nature in its experimental measurement, it can give a superior method to determine the top-quark short-distance mass at hadron colliders.
