Possible explanation of excess events in the search for jets, missing transverse momentum and a Z boson in pp collisions

TL;DR

This paper investigates whether supersymmetric extensions of the Standard Model, particularly within the NMSSM framework, can explain the excess of events observed in ATLAS data involving jets, missing transverse momentum, and a Z boson, while satisfying other experimental constraints.

Contribution

It proposes an alternative SUSY scenario with two massive neutralinos within the NMSSM that better fits the observed excess and distributions compared to GMSB-like models.

Findings

GMSB-like scenarios conflict with constraints and do not fit the data well.

A two-neutralino scenario within NMSSM improves fit to data and distributions.

The proposed model can explain the excess events observed by ATLAS.

Abstract

We study to which extent SUSY extensions of the Standard Model can describe the excess of events of 3.0 standard deviations observed by ATLAS in the on-Z signal region, respecting constraints by CMS on similar signal channels as well as constraints from searches for jets and E^{miss}_T. GMSB-like scenarios are typically in conflict with these constraints, and do not reproduce well the shape of the E^{miss}_T distribution of the data. An alternative scenario with two massive neutralinos can improve fits to the total number of events as well as to the H_T and E^{miss}_T distributions. Such a scenario can be realised within the NMSSM.