Search for Z' --> e+ e- using dielectron mass and angular distribution.
Phys Rev Lett 96:21 (2006) 211801
Abstract:
We search for Z' bosons in dielectron events produced in pp collisions at square root of s = 1.96 TeV, using 0.45 fb(-1) of data accumulated with the Collider Detector at Fermilab II detector at the Fermilab Tevatron. To identify the Z' --> e+ e- signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z' mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z', as well as on the contact-interaction mass scales for different helicity structure scenarios.Search for high-mass resonances decaying to emu in pp collisions at square root = 1.69 TeV.
Phys Rev Lett 96:21 (2006) 211802
Abstract:
We describe a general search for resonances decaying to a neutral emu final state in pp collisions at a center-of-mass energy of 1.96 TeV. Using a data sample representing 344 pb(-1) of integrated luminosity recorded by the Collider Detector at Fermilab II experiment, we compare standard model predictions with the number of observed events for invariant masses between 50 and 800 GeV/c2. Finding no significant excess (5 events observed vs 7.7 +/- 0.8 expected for M(emu) > 100 GeV/c2 ), we set limits on sneutrino and Z' masses as functions of lepton family number violating couplings.Measurement of bottom-quark hadron masses in exclusive J/psi decays with the CDF detector.
Phys Rev Lett 96:20 (2006) 202001
Abstract:
We measure the masses of b hadrons in exclusively reconstructed final states containing a J/psi --> mu-mu+ decay using 220 pb(-1) of data collected by the CDF II experiment. We find: m(B+) = 5279.10 +/- 0.41(stat.) +/- 0.36(sys.) MeV/c2, m(B0) = 5279.63 +/- 0.53(stat.) +/- 0.33(sys.) MeV/c2, m(B(s)0) = 5366.01 +/- 0.73(stat.) +/- 0.33(sys.) MeV/c2, m(lambda(b)0) = 5619.7 +/- 1.2(stat.) +/- 1.2(sys.) MeV/c2. m(B+) - m(B0) = -0.53 +/- 0.67(stat.) +/- 0.14(sys.) MeV/c2, m(B(s)0) - m(B0) = 86.38 +/- 0.90(stat.) +/- 0.06(sys.) MeV/c2, m(lambda(b)0) - m(B0) = 339.2 +/- 1.4(stat.) +/- 0.1(sys.) MeV/c2. The measurements of the B(s)0, lambda(b)0 mass, m(B(s)0) - m(B0) and m(lambda(b)0) - m(B0) mass difference are of better precision than the current world averages.Measurement of the top quark mass with the dynamical likelihood method using lepton plus jets events with b-tags in pp̄ collisions at s=1.96TeV
Physical Review D Particles Fields Gravitation and Cosmology 73:9 (2006)
Abstract:
This paper describes a measurement of the top quark mass, Mtop, with the dynamical likelihood method (DLM) using the CDF II detector at the Fermilab Tevatron. The Tevatron produces top/antitop (tt̄) pairs in pp̄ collisions at a center-of-mass energy of 1.96 TeV. The data sample used in this analysis was accumulated from March 2002 through August 2004, which corresponds to an integrated luminosity of 318pb-1. We use the tt̄ candidates in the "lepton+jets" decay channel, requiring at least one jet identified as a b quark by finding a displaced secondary vertex. The DLM defines a likelihood for each event based on the differential cross section as a function of Mtop per unit phase space volume of the final partons, multiplied by the transfer functions from jet to parton energies. The method takes into account all possible jet combinations in an event, and the likelihood is multiplied event by event to derive the top quark mass by the maximum likelihood method. Using 63 tt̄ candidates observed in the data, with 9.2 events expected from background, we measure the top quark mass to be 173.2+2.6-2.4(stat.)±3. 2(syst.)GeV/c2, or 173.2+4.1-4.0GeV/c2. © 2006 The American Physical Society.Top-quark mass measurement from dilepton events at CDF II.
Phys Rev Lett 96:15 (2006) 152002