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 (l), a photon
(gamma), significant transverse momentum imbalance (missing E(t)), and
a jet identified as containing a b-quark, to SM predictions. The search
uses data produced in proton-antiproton collisions at s**(1/2) ñ.96 TeV
corresponding to 1.9 fb-1 of integrated luminosity taken with the CDF
detector at the Fermilab Tevatron. We find 28 ell gamma_b missing E(t)
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, tt-bar + gamma. In the
data we observe 16 tt-bar gamma candidate events versus an expectation
from non-top-quark 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 tt-bar gamma cross section
to be 0.15 +/- 0.08 pb.
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Updated: Wednesday, 2009 August 19 11:12:36 CDT automatically from input from carol picciolo