Light Sgoldstino: Precision Measurements versus Collider Searches

TL;DR

This work investigates how low-energy, real sgoldstino states constrain the SUSY-breaking scale via a comprehensive set of processes. Using an effective Lagrangian that includes one- and two-sgoldstino couplings, the authors compute decay widths and production rates, mapping them to bounds on $\\sqrt{F}$ across mass ranges from sub-keV to several GeV. Astrophysical constraints (e.g., from Primakoff production, HB stars, SN1987A) typically set the strongest limits for very light sgoldstinos, while heavier states up to a few GeV are probed by flavor-conserving meson decays and, with large flavor violation, by kaon and lepton decays; flavor-violating processes can reach sensitivity to $\\sqrt{F}$ up to about $10^7$ GeV given current MSSM off-diagonal mass terms. The study also shows that two-sgoldstino processes, though rarer, provide complementary constraints that scale as $\\propto F^{-4}$ and can constrain $\\sqrt{F}$ at the TeV scale in tuned scenarios. Overall, precision, flavor-sensitive low-energy measurements can surpass collider searches in constraining SUSY-breaking scales for models with light sgoldstinos, highlighting the important role of astrophysical, laboratory, and flavor observables in probing SUSY-breaking dynamics.

Abstract

We study sensitivity of low-energy experiments to the scale of supersymmetry breaking $\sqrt{F}$ in models with light sgoldstinos --- superpartners of goldstino. The limits on $\sqrt{F}$ may be obtained from direct and indirect measurements of sgoldstino coupling to photons, leptons, mesons and nucleons. There are three sources of constraints: ($i$) astrophysics and cosmology; ($ii$) precision laboratory experiments at low energies; ($iii$) rare decays. We discuss only processes with real sgoldstinos. For sgoldstino lighter than a few MeV and superpartner masses of the order of electroweak scale, astrophysical and reactor bounds on $\sqrt{F}$ are significantly stronger than limits which may be reached at future colliders. In models with heavier sgoldstino (up to 5 GeV), constraints from flavor conserving decays of mesons are complementary to ones coming from collider experiments. The most sensitive probes of sgoldstinos are flavor violating processes, provided that flavor is violated in squark and/or slepton sector. It is shown that sgoldstino contributions into FCNC and lepton flavor violation are strong enough to probe the supersymmetry breaking scale up to $\sqrt{F}\sim10^7$ GeV, if off-diagonal entries in squark (slepton) mass matrices are close to the current limits in MSSM.

Figures (4)

• Figure 1: Branching ratios of scalar sgoldstino decays into photons (thick line), $e^+e^-$ (long dashed line), $\mu^+\mu^-$ (thin line) and $\pi^0\pi^0$ (short dashed line) in models with: a) $|A|=M_{\gamma\gamma}=M_3=100$ GeV; b) $M_{\gamma\gamma}=M_3=100$ GeV, $|A|=1$ TeV; c) $A=M_3=100$ GeV, $M_{\gamma\gamma}=1$ TeV; d) $|A|=M_{\gamma\gamma}=100$ GeV, $M_3=1$ TeV.
• Figure 2: Diagrams contributing to vector meson decay into sgoldstino and photon.
• Figure 3: a) The diagram illustrating $\pi^0$ decay into two sgoldstinos due to two-sgoldstino interaction; b) diagram of $\pi^0$ decay into two photons and sgoldstino due to one-sgoldstino interaction.
• Figure :