Search for a feebly interacting particle X in the decay K+ -> pi X+

Abstract

A search for the K+ -> pi X+ decay, where X is a long-lived feebly interacting particle, is performed through an interpretation of the K+ -> pi+nu nu analysis of data collected in 2017 by the NA62 experiment at CERN. Two ranges of X masses, 0-110 MeV/c(2) and 154-260 MeV/c(2), and lifetimes above 100 ps are considered.

The limits set on the branching ratio, BR(K+ -> pi X+), are competitive with previously reported searches in the first mass range, and improve on current limits in the second mass range by more than an order of magnitude.

Keywords

• Beyond Standard Model
• Exotics
• Fixed target experiments