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Appel, J A

Publications and source records attributed to Appel, J A.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Search for a heavy vector boson decaying to two gluons in pp̄ collisions at √s=1.96 TeV

We present a search for a new heavy vector boson Z' that decays to gluons. Decays to on-shell gluons are suppressed, leading to a dominant decay mode of Z'→g*g. We study the case where the off-shell gluon g* converts to a pair of top quarks, leading to a final state of tt¯g. In a sample of events with exactly one charged lepton, large missing transverse momentum and at least five jets, corresponding to an integrated luminosity of 8.7 fb⁻¹ collected by the CDF II detector, we find the data to be consistent with the standard model. We set upper limits on the production cross section times branching ratio of this chromophilic Z' at 95% confidence level from 300 to 40 fb for Z' masses ranging from 400 to 1000 GeV/c², respectively.

Aaltonen, T.↗
DOE OSTI2012

Search for the standard model Higgs boson produced in association with a W ± boson with 7.5 fb⁻¹ integrated luminosity at CDF

We present a search for the standard model Higgs boson produced in association with a W ± boson. This search uses data corresponding to an integrated luminosity of 7.5 fb⁻¹ collected by the CDF detector at the Tevatron. We select WH→lνbb¯ candidate events with two jets, large missing transverse energy, and exactly one charged lepton. We further require that at least one jet be identified to originate from a bottom quark. Discrimination between the signal and the large background is achieved through the use of a Bayesian artificial neural network. The number of tagged events and their distributions are consistent with the standard model expectations. We observe no evidence for a Higgs boson signal and set 95% C.L. upper limits on the WH production cross section times the branching ratio to decay to bb¯ pairs, σ(pp¯→W ± H)×B(H→bb¯), relative to the rate predicted by the standard model. For the Higgs boson mass range of 100 to 150 GeV/c² we set observed (expected) upper limits from 1.34 (1.83) to 38.8 (23.4). For 115 GeV/c² the upper limit is 3.64 (2.78). The combination of the present search with an independent analysis that selects events with three jets yields more stringent limits ranging from 1.12 (1.79) to 34.4 (21.6) in the same mass range. For 115 and 125 GeV/c² the upper limits are 2.65 (2.60) and 4.36 (3.69), respectively.

Aaltonen, T.↗
DOE OSTI2012

Transverse momentum cross section of $e^+e^-$ pairs in the $Z$-boson region from $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV

The transverse momentum cross section of e{sup +}e{sup -} pairs in the Z-boson mass region of 66-116 GeV/c{sup 2} is precisely measured using Run II data corresponding to 2.1 fb{sup -1} of integrated luminosity recorded by the Collider Detector at Fermilab. The cross section is compared with quantum chromodynamic calculations. One is a fixed-order perturbative calculation at O({alpha}{sub s}{sup 2}), and the other combines perturbative predictions at high transverse momentum with the gluon resummation formalism at low transverse momentum. Comparisons of the measurement with calculations show reasonable agreement. The measurement is of sufficient precision to allow refinements in the understanding of the transverse momentum distribution.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗