Analytic two-loop form factors for chi_{Q,J} production and decay are presented, including a new NRQCD singularity that couples P-wave states to the 3S1[8] configuration.
No Landau-Yang in QCD
1 Pith paper cite this work. Polarity classification is still indexing.
1
Pith paper citing it
abstract
The Landau-Yang theorem, forbidding transition amplitudes between a massive spin-1 particle and two photons, is widely assumed to apply to other massless spin-1 particles. We show that this is not true in Standard-Model QCD, so that for instance antisymmetric colour-octet spin-1 quarkonia can be formed by two on-shell gluons in second-order perturbative QCD.
citation-role summary
background 1
citation-polarity summary
fields
hep-ph 1years
2025 1verdicts
CONDITIONAL 1roles
background 1polarities
unclear 1representative citing papers
citing papers explorer
-
Two-loop form factors for $P$-wave quarkonium production and decay
Analytic two-loop form factors for chi_{Q,J} production and decay are presented, including a new NRQCD singularity that couples P-wave states to the 3S1[8] configuration.