Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

New Physics Searches at BESIII

Vindhyawasini Prasad

TL;DR

This work surveys BESIII results targeting new physics in the low- to mid-GeV range, focusing on dark-sector portals such as dark photons, light Higgs bosons, ALPs, and muon-philic bosons, as well as invisible final-state signatures and baryon-number violation. It employs radiative $J/psi$ decays, double-tag techniques, and large tau–charm data samples to derive stringent upper limits on branching fractions and couplings across multiple channels, with no significant signals observed. Key contributions include leading constraints on massless dark photons in charm decays, sub-GeV invisible particles, a dark baryon, muon-philic bosons, and invisible $K_S^0$ decays, plus improved bounds on $\Lambda-\bar{\Lambda}$ oscillation parameters. The results tightly constrain hidden-sector models in the MeV–GeV regime and complement high-energy collider searches, with future data at the $\psi(3770)$ energy expected to further improve sensitivity.

Abstract

This report highlights the recent BESIII results related to the new physics searches motivated by the shortcomings of Standard Model, such as the exclusion of dark matter (DM). DM has so far been inferred only through astrophysical observations and accounts for a large fraction of matter density of the universe. DM may couple to SM particles via various portals. These portals give rise to several possible new particles beyond the SM, such as light Higgs bosons, dark photons, axion-like particles, or spin-1/2 fermions. Furthermore, the origin of DM and the observed asymmetry between visible matter and antimatter may be connected through the introduction of a dark baryon. The signature of these new physics particles could be accessible by the BESIII if their masses lie in the few-GeV range.

New Physics Searches at BESIII

TL;DR

This work surveys BESIII results targeting new physics in the low- to mid-GeV range, focusing on dark-sector portals such as dark photons, light Higgs bosons, ALPs, and muon-philic bosons, as well as invisible final-state signatures and baryon-number violation. It employs radiative decays, double-tag techniques, and large tau–charm data samples to derive stringent upper limits on branching fractions and couplings across multiple channels, with no significant signals observed. Key contributions include leading constraints on massless dark photons in charm decays, sub-GeV invisible particles, a dark baryon, muon-philic bosons, and invisible decays, plus improved bounds on oscillation parameters. The results tightly constrain hidden-sector models in the MeV–GeV regime and complement high-energy collider searches, with future data at the energy expected to further improve sensitivity.

Abstract

This report highlights the recent BESIII results related to the new physics searches motivated by the shortcomings of Standard Model, such as the exclusion of dark matter (DM). DM has so far been inferred only through astrophysical observations and accounts for a large fraction of matter density of the universe. DM may couple to SM particles via various portals. These portals give rise to several possible new particles beyond the SM, such as light Higgs bosons, dark photons, axion-like particles, or spin-1/2 fermions. Furthermore, the origin of DM and the observed asymmetry between visible matter and antimatter may be connected through the introduction of a dark baryon. The signature of these new physics particles could be accessible by the BESIII if their masses lie in the few-GeV range.
Paper Structure (10 sections, 2 equations, 3 figures)

This paper contains 10 sections, 2 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Search for light gauge boson via radiative $J/\psi$ decay
  3. New physics signature with invisible final state
  4. Search for massless dark photon via $D^0 \to \omega \gamma'$ and $D^0 \to \gamma \gamma'$
  5. Search for sub-GeV invisible particle in $J/\psi \to \phi X$
  6. Search for a dark baryon in the $\Xi^- \to \pi^- + {\rm invisible}$ decay
  7. Search for muon-philic scalar or vector particle in $J/\psi \to \mu^+\mu^- {\rm invisible}$
  8. Invisible $K_S^0$ decays
  9. Search for $\Lambda-\bar{\Lambda}$ osicallation
  10. Summary

Figures (3)

  • Figure 1: (Left) $90\%$ CL upper limits on the mixing angle $\sin^2\theta_{A^0}$ as a function of the $A^0$ mass. (Right) $95\%$ CL upper limits on the axion–photon coupling $g_{a\gamma\gamma}$ as a function of the ALP mass $m_a$.
  • Figure 2: (Left) The $90\%$ CL upper limits on the effective coupling operator $|C|^2 + |C_5|^2$ obtained from the explored decay mode in massless dark photon searches. (Right) The $90\%$ CL upper limits on $\mathcal{B}(J/\psi \to \phi +X)$ as a function of sub-GeV invisible particle $X$ mass.
  • Figure 3: (Left) The $95\%$ CL upper limits on the expected and observed branching fractions of $\Xi^- \to \pi^- +{\rm invisible}$ as a function of dark baryon mass. (Right) The $95\%$ CL upper limits on the Wilson coefficients $C_{us,s}^L$ and $C_{us,s}^{R}$ derived from the results under different mass hypotheses, together with those from LHC searches.