Search for large extra dimensions in final states containing one photon or jet and large missing transverse energy produced in p anti-p collisions at s**(1/2) = 1.96-TeV

The authors present the results of searches for large extra dimensions in samples of events with large missing transverse energy E{sub T} and either a photon or a jet produced in p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector. For {gamma} + E{sub T} and jet + E{sub T} candidate samples corresponding to 2.0 fb{sup -1} and 1.1 fb{sup -1} of integrated luminosity respectively, they observe good agreement with standard model expectations and obtain a combined lower limit on the fundamental parameter of the large extra dimensions model, M{sub D}, as a function of the number of extra dimensions in the model

Search for Standard Model Higgs Boson Production in Association with a W Boson at CDF

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (p{bar p} {yields} W{sup {+-}}H {yields} {ell}{nu}b{bar b}) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 1 fb{sup -1}. We select events consistent with a signature of a single lepton (e{sup {+-}}/{mu}{sup {+-}}), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a neural network filter technique. The observed number of events and the dijet mass distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio ranging from 3.9 to 1.3 pb for Higgs boson masses from 110 to 150 GeV/c{sup 2}, respectively

Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging

We present a measurement of the electric charge of the top quark using p{bar p} collisions corresponding to an integrated luminosity of 2.7 fb{sup -1} at the CDF II detector. We reconstruct t{bar t} events in the lepton+jets final state and use kinematic information to determine which b-jet is associated with the leptonically- or hadronically-decaying t-quark. Soft lepton taggers are used to determine the b-jet flavor. Along with the charge of the W boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with 2.4 {+-} 0.8 expected background events, 29 are reconstructed as tt with the standard model +2/3 charge, whereas 16 are reconstructed as t{bar t} with an exotic -4/3 charge. This is consistent with the standard model and excludes the exotic scenario at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose

Search for Standard Model Higgs Boson Production in Association with a W Boson using a Neural Network

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (p{bar p} {yields} W{sup {+-}}H {yields} {ell}{nu}b{bar b}) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector that correspond to an integrated luminosity of approximately 1.9 fb{sup -1}. We select events consistent with a signature of a single charged lepton (e{sup {+-}}/{mu}{sup {+-}}), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method, a jet probability tagging method, and a neural network filter. We use kinematic information in an artificial neural network to improve discrimination between signal and background compared to previous analyses. The observed number of events and the neural network output distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching fraction ranging from 1.2 to 1.1 pb or 7.5 to 102 times the standard model expectation for Higgs boson masses from 110 to 150 GeV/c{sup 2}, respectively

Cross Section Measurements of High-p(T) Dilepton Final-State Processes Using a Global Fitting Method

The authors present a new method for studying high-p{sub T} dilepton events (e{sup {+-}}e{sup {-+}}, {mu}{sup {+-}}{mu}{sup {-+}}, e{sup {+-}}{mu}{sup {-+}}) and simultaneously extracting the production cross sections of p{bar p} {yields} t{bar t}, p{bar p} {yields} W{sup +}W{sup -}, and p{bar p} {yields} Z{sup 0} {yields} {tau}{sup +}{tau}{sup -} at a center-of-mass energy of {radical}s = 1.96 TeV. They perform a likelihood fit to the dilepton data in a parameter space defined by the missing transverse energy and the number of jets in the event. The results, which use 360 pb{sup -1} of data recorded with the CDF II detector at the Fermilab Tevatron Collider, are {sigma}(t{bar t}) = 8.5{sub -2.2}{sup +2.7} pb, {sigma}(W{sup +}W{sup -}) = 16.3{sub -4.4}{sup +5.2} pb, and {sigma}(Z{sup 0} {yields} {tau}{sup +}{tau}{sup -}) = 291{sub -46}{sup +50} pb

SUSY Les Houches Accord 2

The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first SLHA to include various generalizations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavor, as well as the simplest next-to-minimal model

Analysis of the quantum numbers J**PC of the X(3872)

The authors present an analysis of angular distributions and correlations of the X(3872) in the exclusive decay mode X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -} with J/{psi} {yields} {mu}{sup +}{mu}{sup -}. They use 780 pb{sup -1} of data from p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. They derive constraints on spin, parity, and charge conjugation parity of the X(3872) by comparing measured angular distributions of the decay products with predictions for different J{sup PC} hypotheses. The assignments J{sup PC} = 1{sup ++} and 2{sup -+} are the only ones consistent with the data

Search for the Higgs Boson and Technicolor Particles in p anti-p Colisions at sqrt(s) = 1.8 TeV

In the Standard Model (SM) of the elementary particles, the interactions among the known fundamental fermions (leptons and quarks) are mediated through gauge bosons which obey the symmetry: SU(3) {circle_times} SU(2) {circle_times} U(1). More precisely, the electroweak interaction [4-6] is described by a gauge symmetry SU(2) {circle_times} U(1) which is broken spontaneously. The electroweak symmetry breaking is implemented by the introduction of a complex scalar Higgs field which has a non-zero vacuum expectation value (vev). This way, the lagrangian of the theory remains invariant under SU(2) transformations, but quantization of the fields must start from a ground state which does not exhibit this symmetry, and therefore the full symmetry of the lagrangian is not manifest. Invariance of the theory under local SU(2) transformations implies the presence of vectorial gauge fields which mediate the electroweak interactions. The so called spontaneous symmetry breaking allows the quanta of these gauge fields, the W and Z bosons, to acquire a finite mass. The photon, the particle which mediates the electromagnetic interaction, remains massless. The Higgs boson is one of only two particles in the SM which have not yet been directly observed (the other is the {nu}{sub {tau}}, although there is indirect evidence of its existence). Although the SM does not predict the Higgs mass, a lower limit {approx} 100 GeV/c{sup 2} is set by LEPII data, and theoretical considerations prefer Higgs masses not higher than a few hundred GeV/c{sup 2}. At the Tevatron, a search for the Higgs boson is hard due to the small production cross section and the huge backgrounds that do not allow to see the signal clearly. It is still interesting, however, to perform sensitivity studies at the Tevatron. The easiest production channel to observe at the Tevatron is the associated production of Higgs with weak (W or Z) bosons. The Higgs boson coupling to the fermions increases with fermion mass, so the most likely decay in the mass range they are interested, M(H{sup 0}) {approx} 100 GeV/c{sup 2}, in is H {yields} b{bar b}. There are different possible final states depending on the decay of the associated vector boson: two jets plus lepton plus missing transverse energy (leptonic channel) and four jets (hadronic channel). In the former, the presence of a highly energetic, isolated lepton makes it relatively easy to reduce the background, while the latter has a larger production cross section times branching fraction, but it also has a huge amount of irreducible QCD background. CDF has searched for the Higgs boson in both final states, setting upper limits on the production cross sections