Study of the ρ and ω meson decays into a pseudoscalar meson and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math> pair with the CMD-2 detector

Based on a sample of ð225.3 AE 2.8Þ × 10 6 J=ψ events collected with the BESIII detector, the electromagnetic Dalitz decays of J=ψ → Pe þ e − ðP ¼ η 0 =η=π 0 Þ are studied. By reconstructing the pseudoscalar mesons in various decay modes, the decays J=ψ → η 0 e þ e − , J=ψ → ηe þ e − , and J=ψ → π 0 e þ e − are observed for the first time. The branching fractions are determined to be BðJ=ψ → η 0 e þ e − Þ ¼ ð5.81 AE 0.16 AE 0.31Þ × 10 −5 , BðJ=ψ → ηe þ e − Þ ¼ ð1.16 AE 0.07 AE 0.06Þ × 10 −5 , and BðJ=ψ → π 0 e þ e − Þ ¼ ð7.56 AE 1.32 AE 0.50Þ × 10 −7 , where the first errors are statistical and the second ones systematic.

Section: Introductionmentioning

confidence: 73%

Observation of electromagnetic Dalitz decaysJ/ψ→Pe+e−

Ablikim¹,

Ачасов

Ai³

et al. 2014

“…0 þ À . It would certainly be helpful, especially in light of a theoretical analysis of contributions to light-by-light scattering, if precision data for additional channels could be obtained [36].…”

Section: Discussionmentioning

confidence: 99%

ω→π0γandϕ→π0γtransition form factors in dispersion

Schneider¹,

Kubis²,

Niecknig³

2012

125

168

We calculate the ! ! 0 Ã and ! 0 Ã electromagnetic transition form factors based on dispersion theory, relying solely on a previous dispersive analysis of the corresponding three-pion decays and the pion vector form factor. We compare our findings to recent measurements of the ! ! 0 þ À decay spectrum by the NA60 collaboration, and strongly encourage experimental investigation of the OkuboZweig-Iizuka forbidden ! 0 ' þ ' À decays in order to understand the strong deviations from vectormeson dominance found in these transition form factors.

“…The Dalitz decay, also known as the leptonic conversion decay, provides additional information about the meson structure owing to the virtual photon kinematics. Though widely observed in the light meson sector, such as φ → π 0 e + e − [8], φ → ηe + e − [9,10], and ω → π 0 e + e − [11,12], only a few such decays have been detected in the heavy sector. The observed Dalitz decays of quarkonium are decays to a light meson plus a lepton pair, such as J/ψ → ηe + e − , J/ψ → η e + e − [13], and ψ(3686) → η e + e − [14].…”

Section: Introductionmentioning

confidence: 99%

Frame dependence of transition form factors in light-front dynamics

Maris

et al. 2019

We study the radiative transitions between vector and pseudoscalar quarkonia in the light-front Hamiltonian approach, and investigate the effects of using different current component and different reference frames. In practical calculations with truncated Fock spaces, transition form factors may acquire current component dependence and frame dependence, and such dependences could serve as a measure for the Lorentz symmetry violation. We suggest using the transverse current with m j = 0 state of the vector meson, since this procedure employs the dominant spin components of the light-front wavefunctions and is more robust in practical calculations. We calculate the transition form factor between vector and pseudoscalar quarkonia and investigate the frame dependence with light-front wavefunctions calculated from the valence Fock sector. We suggest using frames with minimal longitudinal momentum transfer for calculations in the valence Fock sector, namely the Drell-Yan frame for the space-like region and a specific longitudinal frame for the timelike region; at q 2 = 0 these two frames give the same result.