Search forCPandPviolating pseudoscalar decays intoππ

Abstract

Using a sample of (225.2±2.8)×10 6 J/ψ events collected with the Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider, CP and P violating decays of η, η ′ and η c into π + π − and π 0 π 0 are searched for in J/ψ radiative decays. No significant η, η ′ or η c signal is observed, and 90% confidence level upper limits of

LHCb searches for the strong CP-violating decays η → ππ and η′ → ππ

“…The current best limit for the η → π + π − decay mode, B (η → π + π − ) < 1.3 × 10 −5 at 90% confidence level (CL), is obtained from the KLOE experiment [6], which looked for η → π + π − in the decay φ(1020) → ηγ. The limit for η , B (η → π + π − ) < 5.5 × 10 −5 at 90% CL, is from the BESIII experiment [7], based on searches for η → π + π − in radiative J/ψ → η γ decays. In the study presented here, a new method is introduced to search for the decays η → π + π − and η → π + π − , exploiting the large sample of charm mesons collected by LHCb; any contribution would show as narrow peaks, consistent with mass resolution, in the inclusive π + π − mass spectra.…”

Search for intermediate resonances and dark gauge bosons in J/ψ→γπ0η′

“…Using a sample of 225 million J=ψ events, BESIII reports the results of the search for η c → π þ π − and η c → π 0 π 0 and upper limits on the branching fractions are presented at the 90% confidence level (C.L.) [4]. In this paper, we present the first experimental search for η c → π 0 η 0 .…”

Recent results from BESIII

“…This program of BESIII resulted so far in a variety of papers that can be found in Refs. [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. The bulk of the activities below the open-charm threshold focuses on precision measurements of the properties of charmonium states, such as their masses, total widths, line shapes, and partial decay rates.…”