First results on a search for light pseudoscalar sgoldstino in K- decays

TL;DR

This study conducted a search for light pseudoscalar sgoldstino particles in K- decays using the ISTRA+ detector, setting new upper limits on their production, especially at higher masses, with no signal detected.

Contribution

First experimental search for pseudoscalar sgoldstino in K- decays at higher masses, improving existing upper limits and providing new constraints.

Findings

No signal observed for sgoldstino production.

Established upper limits on branching ratios between 2.0×10^-5 and 0.5×10^-5.

Results extend constraints to higher mass range up to 190 MeV.

Abstract

A search for the light pseudoscalar sgoldstino production in three-body K- decay K- --> pi-pi0 P has been performed with the ISTRA+ detector exposed to the 25 GeV negative secondary of the U-70 proton synchrotron. No signal is seen. Upper limits for the branching ratio at 90% confidence level vary between 2.0 10**-5 and 0.5 10**-5 in the effective mass m(P) range from 0 up to 190 MeV. Our results improve the limits published by the E787 Collaboration in the mass interval between 0 and 120 MeV and are the first ones at higher masses.