Study of η′ → π+π−l+l− decays at BESIII
Yükleniyor...
Tarih
2024
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Springer science and bsiness media deutschland GmbH
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
With a sample of (10087 +/- 44) x 10(6)J/psi events accumulated with the BESIII detector, we analyze the decays eta ' -> pi(+)pi(-)l(+)l(-)(l = e, mu) via the process J/psi -> gamma eta '. The branching fractions are measured to be B(eta ' -> pi(+)pi(-)e(+)e(-)) = (2.45 +/- 0.02(stat.) +/- 0.08(syst.)) x 10(-3) and B(eta ' -> pi(+)pi(-)mu(+)mu(-)) = (2.16 +/- 0.12(stat.) +/- 0.06(syst.)) x 10(-5), and the ratio is B(eta '->pi(+)pi(-)e(+)e(-))/B(eta '->pi(+)pi(-)mu(+)mu(-)) =113.4 +/- 0.9(stat.) +/- 3.7(syst.). In addition, by combining the eta ' -> pi(+)pi(-)e(+)e(-) and eta ' -> pi(+)pi(-)mu(+)mu(-) decays, the slope parameter of the electromagnetic transition form factor is measured to be b(eta ')=1.30 +/- 0.19 (GeV/c(2))(-2), which is consistent with previous measurements from BESIII and theoretical predictions from the VMD model. The asymmetry in the angle between the pi(+)pi(-) and l(+)l(-) decay planes, which has the potential to reveal the CP-violation originating from an unconventional electric dipole transition, is also investigated. The asymmetry parameters are determined to be A(CP)(eta '->pi(+)pi(-)e(+)e(-)) = (-0.21 +/- 0.73(stat.) +/- 0.01(syst.))% and A(CP)(eta '->pi(+)pi(-)mu(+)mu(-)) = (0.62 +/- 4.71(stat.) +/- 0.08(syst.))%, implying that no evidence of CP-violation is observed at the present statistics. Finally, an axion-like particle is searched for via the decay eta ' -> pi(+)pi(-)a, a -> e(+)e(-), and upper limits of the branching fractions are presented for the mass assumptions of the axion-like particle in the range of 0 - 500 MeV/c(2).
Açıklama
Anahtar Kelimeler
CP Violation, Dark Matter, e+-e− Experiments, QCD
Kaynak
Journal of high energy physics
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
Sayı
7
Künye
Ablikim, M., Achasov, M. N., Adlarson, P., Afedulidis, O., Ai, X. C., Aliberti, R., ... & Hölzken, F. (2024). Study of η′→ π+ π− l+ l− decays at BESIII. Journal of High Energy Physics, 2024(7), 1-27.
