Searching the Inclusive Lepton + Photon + Missing ET + b-quark Signature for Radiative Top Quark Decay and Non-Standard-Model Processes

TL;DR

This study searches for rare events involving leptons, photons, missing energy, and b-quarks to identify potential signs of new physics or non-standard-model processes, focusing on top quark production with an additional photon.

Contribution

It provides the first measurement of the ttg cross section in events with a lepton, photon, and b-jet, testing SM predictions and probing for new phenomena.

Findings

Observed 28 lepton+photon+MET+b events, consistent with SM expectations.

Identified an excess of ttbar+photon candidate events, estimating the cross section as 0.15 +- 0.08 pb.

Supports the SM prediction for top quark production with additional radiation.

Abstract

In a search for new phenomena in a signature suppressed in the standard model of elementary particles (SM), we compare the inclusive production of events containing a lepton, a photon, significant transverse momentum imbalance (MET), and a jet identified as containing a b-quark, to SM predictions. The search uses data produced in proton-antiproton collisions at 1.96 TeV corresponding to 1.9 fb-1 of integrated luminosity taken with the CDF detector at the Fermilab Tevatron. We find 28 lepton+photon+MET+b events versus an expectation of 31.0+4.1/-3.5 events. If we further require events to contain at least three jets and large total transverse energy, simulations predict that the largest SM source is top-quark pair production with an additional radiated photon, ttbar+photon. In the data we observe 16 ttbar+photon candidate events versus an expectation from SM sources of 11.2+2.3/-2.1. Assuming the difference between the observed number and the predicted non-top-quark total is due to SM top quark production, we estimate the ttg cross section to be 0.15 +- 0.08 pb.