Speaker
Description
Currently, there is no experimental evidences of the violation of the spatial parity (P) conservation in strong interactions. However, the in the QCD theory, the P-breaking term (so-called $\theta$-term) can be included, with tight limits on the $\theta$ parameter value. However, in the medium with high temperature and at large topological fluctuations [1] of QCD fields, expected in collisions of the heavy ions at high energy, the effects of the local violation of P-symmetry can appear. The contribution to the QCD Lagrangian of the topological charge can play role of an effective $\theta$-term [2]. As a consequence, some hadrons would decay in channels that forbidden by the global parity conservation.
In particular, search for decays of a charged a0 meson into charged pion and photon has been proposed [3] as a signature of the local parity breaking in the strong interactions. However the expected electromagnetic cross section of the decay $a_0^\pm \rightarrow \pi^\pm+\gamma$ is rather low making the experimental searches quite challenger [4]. In this work we investigate the hadronc analogue of such process, namely, decay of a charged a0 meson into three charged pions. Both the direct threeparticle decay and a resonance one, with intermediate $\rho^0$ meson ( $a_0^\pm \rightarrow \rho^0 + \pi^\pm \rightarrow \pi^\pm+ \pi^\mp + \pi^\pm$ ) are considered. We study an invariant-mass spectrum of three charged mesons using PYTHIA Monte Carlo generator with enabled required decay channels. To distinguish the peak of mentioned decay from the background the mixed-event substracting, kinematic cuts and Dalitz plots analysis were used. As a result we have estimated minimal number of pp collision events for significant signal of the P-breaking decay.
The study was funded by the Russian Science Foundation grant No. 22-22-00493,
https://rscf.ru/en/project/22-22-00493/
References:
[1] D. Kharzeev, Annals of Physics, 325, 1. 205 – 218 (2010).
[2] A.Andrianov, D.Espriu and X.Planells, Eur. Phys. J. C73 (2013) no.1, 2294
[3] A. Andrianov et al, EPJ Web of Conferences 158, 03012 (2017).
[4] V. Petrov, V. Kovalenko, The possibility of finding the P-symmetry breaking decay of the charged a0 meson, ICPPA-2022, https://indico.particle.mephi.ru/event/275/contributions/3360/
