χ c2 tensor meson transition form factors in the light front approach

Autor: Izabela Babiarz, Roman Pasechnik, Wolfgang Schäfer, Antoni Szczurek
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Journal of High Energy Physics, Vol 2024, Iss 6, Pp 1-21 (2024)
Druh dokumentu: article
ISSN: 1029-8479
DOI: 10.1007/JHEP06(2024)159
Popis: Abstract We continue our work on the light-front formulation of quarkonium γ ∗ γ transition form factors, extending the formalism to J PC = 2++ tensor meson states. We present an analysis of γ ∗ γ → χ c2 transition amplitude and the pertinent helicity form factors. Our relativistic formalism is based on the light-front quark-antiquark wave function of the quarkonium. We calculate the two-photon decay width as well as three independent γ ∗ γ transition form factors for J z = 0, 1, 2 as a function of photon virtuality Q 2. We compare our results for the two-photon decay width to the recently measured ones by the Belle and BES III collaborations. Even when including relativistic corrections, a very small Γ(λ = 0)/Γ(λ = 2) ~ 10 −3 ratio is found which is beyond present experimental precision. We also present the form factors as a function of photon virtuality and compare them to the sparse experimental data on the so-called off-shell width. The formalism presented here can be used for other 2++ mesons, excited charmonia or bottomonia or even light q q ¯ $$ q\overline{q} $$ -mesons.
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