Measurement of the top-quark mass with dilepton events selected using neuroevolution at CDF.
Phys Rev Lett 102:15 (2009) 152001
Abstract:
We report a measurement of the top-quark mass M_{t} in the dilepton decay channel tt[over ] --> bl;{'+} nu_{l};{'}b[over ]l;{-}nu[over ]_{l}. Events are selected with a neural network which has been directly optimized for statistical precision in top-quark mass using neuroevolution, a technique modeled on biological evolution. The top-quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0 fb;{-1} of pp[over ] collisions collected with the CDF II detector, yielding a measurement of M_{t} = 171.2 +/- 2.7(stat) +/- 2.9(syst) GeV / c;{2}.Search for top-quark production via flavor-changing neutral currents in W+1 jet events at CDF.
Phys Rev Lett 102:15 (2009) 151801
Abstract:
We report on a search for the non-standard-model process u(c) + g --> t using pp[over ] collision data collected by the Collider Detector at Fermilab II detector corresponding to 2.2 fb;{-1}. The candidate events are classified as signal-like or backgroundlike by an artificial neural network. The observed discriminant distribution yields no evidence for flavor-changing neutral current top-quark production, resulting in an upper limit on the production cross section sigma(u(c) + g --> t) < 1.8 pb at the 95% C.L. Using theoretical predictions we convert the cross section limit to upper limits on flavor-changing neutral current branching ratios: B(t --> u + g) < 3.9 x 10;{-4} and B(t --> c + g) < 5.7 x 10;{-3}.Measurement of the top-quark mass with dilepton events selected using neuroevolution at CDF
Physical Review Letters 102:15 (2009)
Abstract:
We report a measurement of the top-quark mass Mt in the dilepton decay channel tt̄→bl′+νl′b̄l-ν̄l. Events are selected with a neural network which has been directly optimized for statistical precision in top-quark mass using neuroevolution, a technique modeled on biological evolution. The top-quark mass is extracted from per-event probability densities that are formed by the convolution of leading order matrix elements and detector resolution functions. The joint probability is the product of the probability densities from 344 candidate events in 2.0fb-1 of pp̄ collisions collected with the CDF II detector, yielding a measurement of Mt=171.2±2.7(stat)±2.9(syst)GeV/c2. © 2009 The American Physical Society.Dalitz plot analysis of Ds+→K+K-π+
Physical Review D - Particles, Fields, Gravitation and Cosmology 79:7 (2009)
Abstract:
We perform a Dalitz plot analysis of the decay Ds+→K+K-π+ with the CLEO-c data set of 586pb-1 of e+e- collisions accumulated at s=4.17GeV. This corresponds to about 0.57×106 Ds±Ds* pairs from which we select 14400 candidates with a background of roughly 15%. In contrast to previous measurements we find good agreement with our data only by including an additional f0(1370)π+ contribution. We measure the magnitude, phase, and fit fraction of K*(892)0K+, (1020)π+, K0*(1430)K+, f0(980)π+, f0(1710)π+, and f0(1370)π+ contributions and limit the possible contributions of other KK and Kπ resonances that could appear in this decay. © 2009 The American Physical Society.Measurement of the top quark mass at CDF using the "neutrino ø weighting" template method on a lepton plus isolated track sample
Physical Review D - Particles, Fields, Gravitation and Cosmology 79:7 (2009)