Professor Chris Hays

Abstract:

We report a measurement of the difference (ΔACP) between time-integrated CP-violating asymmetries in D0→K+K- and D0→π+π- decays reconstructed in the full data set of proton-antiproton collisions collected by the Collider Detector at Fermilab, corresponding to 9.7fb-1 of integrated luminosity. The strong decay D*+→D0π+ is used to identify the charm meson at production as D0 or D̄0. We measure ΔACP=[-0.62±0.21(stat)±0.10(syst)]%, which differs from zero by 2.7 Gaussian standard deviations. This result supports similar evidence for CP violation in charm-quark decays obtained in proton-proton collisions. © 2012 American Physical Society.

Abstract:

We present a search for the standard model Higgs boson produced in association with a W boson in √s=1.96TeV pp̄ collision data collected with the CDFA II detector at the Tevatron corresponding to an integrated luminosity of 9.45fb-1. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H→bb̄ branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125GeV/c2, we observe (expect) a limit of 4.9 (2.8) times the standard model value. © 2012 American Physical Society.

Abstract:

We present a search for the standard model Higgs boson produced in association with a Z boson in data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45fb-1. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electron or muon pairs, we set 95% credibility level upper limits on the ZH production cross section times the H→bb̄ branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125GeV/c2, we observe (expect) a limit of 7.1 (3.9) times the standard model value. © 2012 American Physical Society.

Abstract:

We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at √s=1.96TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45fb-1. We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a b quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction for several mass hypotheses between 90 and 150GeV/c2. For a Higgs boson mass of 125GeV/c2, the observed (expected) limit is 6.7 (3.6) times the standard model prediction. © 2012 American Physical Society.

Abstract:

We combine the results of searches for the standard model Higgs boson based on the full CDF Run II data set obtained from √s = 1.96 TeV pp¯ collisions at the Fermilab Tevatron corresponding to an integrated luminosity of 9.45 fb−1. The searches are conducted for Higgs bosons that are produced in association with a W or Z boson, have masses in the range 90–150 GeV/c2, and decay into b¯b pairs. An excess of data is present that is inconsistent with the background prediction at the level of 2.5 standard deviations (the most significant local excess is 2.7 standard deviations).