New physics searches at the BESIII experiment

Abstract

The standard model (SM) of particle physics, comprised of the unified electroweak and quantum chromodynamic theories, accurately explains almost all experimental results related to the micro-world, and has made a number of predictions for previously unseen particles, most notably the Higgs scalar boson, that were subsequently discovered. As a result, the SM is currently universally accepted as the theory of the fundamental particles and their interactions. However, in spite of its numerous successes, the SM has a number of apparent shortcomings, including: many free parameters that must be supplied by experimental measurements; no mechanism to produce the dominance of matter over antimatter in the universe; and no explanations for gravity, the dark matter in the universe, neutrino masses, the number of particle generations, etc. Because of these shortcomings, there is considerable incentive to search for evidence for new, non-SM physics phenomena that might provide important clues about what a new, beyond the SM theory (BSM) might look like. Although the center-of-mass energies that BESIII can access are far below the energy frontier, searches for new, BSM physics are an important component of its research program. This report reviews some of the highlights from BESIII’s searches for signs of new, BSM physics by: measuring rates for processes that the SM predicts to be forbidden or very rare; searching for non-SM particles such as dark photons; performing precision tests of SM predictions; and looking for violations of the discrete symmetries C and CP in processes for which the SM expectations are immeasurably small.

New physics searches at kaon and hyperon factories

“…It has accumulated world's largest datasets of 1.0 × 10 9 J/ψ events (corresponding to 3.1 fb −1 integrated luminosity) [7], 3 × 10 9 ψ(3686) events, and 2.9 fb −1 integrated luminosity at ψ(3773), all of which are produced directly from the e + e − collisions. A number of searches for rare decays and physics beyond the SM have been performed by BESIII, utilizing the clean experimental environment [369,370].…”

CP symmetry tests in hyperon weak decays at BESIII

“…The polarization of the daughter baryon, , depends on , , and the , and parameters as illustrated in Fig. 1 [8]. Only two of these three parameters are independent.…”

Search for an axion-like particle in radiative J/ψ decays

“…Via the weak interaction, the J/ψ can potentially decay into a single charm meson via such as D accompanied by some non-charm mesons. Searching for the J/ψ weak decays can provide an experimental test of the Standard Model (SM) [8], which predicts the branching fractions of J/ψ decays containing a D meson up to an order of about 10 −8 [9]. Furthermore, this search may offer a unique opportunity to probe new physics beyond the SM, including the top-color model [10], the minimal supersymmetric SM with or without R-parity violation [11], and the two-Higgs doublet model [12], in which these branching fractions could be enhanced to be as large as 10 −5 [8,13].…”