43 research outputs found
Search for lepton flavor violating decays of a heavy neutral particle in p-pbar collisions at root(s)=1.8 TeV
We report on a search for a high mass, narrow width particle that decays
directly to e+mu, e+tau, or mu+tau. We use approximately 110 pb^-1 of data
collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence
of lepton flavor violating decays is found. Limits are set on the production
and decay of sneutrinos with R-parity violating interactions.Comment: Figure 2 fixed. Reference 4 fixed. Minor changes to tex
Polarizations of J/psi and psi(2S) Mesons Produced in ppbar Collisions at 1.96 TeV
We have measured the polarizations of \jpsi and \psiprime mesons as
functions of their transverse momentum \pt when they are produced promptly in
the rapidity range with \pt \geq 5 \pgev. The analysis is performed
using a data sample with an integrated luminosity of about 800 \ipb collected
by the CDF II detector. For both vector mesons, we find that the polarizations
become increasingly longitudinal as \pt increases from 5 to 30 \pgev. These
results are compared to the predictions of nonrelativistic quantum
chromodynamics and other contemporary models. The effective polarizations of
\jpsi and \psiprime mesons from -hadron decays are also reported.Comment: 8 pages, 7 figures, published in Physical Review Letter
Measurement of ϒ production in pp collisions at √s = 2.76 TeV
The production of ϒ(1S), ϒ(2S) and ϒ(3S)
mesons decaying into the dimuon final state is studied with
the LHCb detector using a data sample corresponding to an
integrated luminosity of 3.3 pb−1 collected in proton–proton
collisions at a centre-of-mass energy of √s = 2.76 TeV. The
differential production cross-sections times dimuon branching
fractions are measured as functions of the ϒ transverse
momentum and rapidity, over the ranges pT < 15 GeV/c
and 2.0 < y < 4.5. The total cross-sections in this kinematic
region, assuming unpolarised production, are measured to be
σ (pp → ϒ(1S)X) × B
ϒ(1S)→μ+μ−
= 1.111 ± 0.043 ± 0.044 nb,
σ (pp → ϒ(2S)X) × B
ϒ(2S)→μ+μ−
= 0.264 ± 0.023 ± 0.011 nb,
σ (pp → ϒ(3S)X) × B
ϒ(3S)→μ+μ−
= 0.159 ± 0.020 ± 0.007 nb,
where the first uncertainty is statistical and the second systematic
Momentum distribution of charged particles in jets in dijet events in p(p)over-bar collisions at root s=1.8 TeV and comparisons to perturbative QCD predictions
Inclusive momentum distributions of charged particles in restricted cones around jet axes were measured in dijet events with invariant dijet masses in the range 80 to 600 GeV/c(2). Events were produced at the Fermilab Tevatron in p (p) over bar collisions with a center of mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The results were compared to perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton-hadron duality. It was shown that the data follow theoretical predictions quite well over the whole range of the jet energies included in this analysis. We extracted the MLLA cutoff scale Q(eff) and found a value of 230+/-40 MeV. The theoretical prediction of E(jet)sin theta(c) scaling, where theta(c) is the cone opening angle, was experimentally observed for the first time. From the MLLA fits to the data, two more parameters were extracted: the ratio of parton multiplicities in gluon and quark jets, r=N-partons(g-jet)/N-partons(q-jet)=1.9+/-0.5, and the ratio of the number of charged hadrons to the number of predicted partons in a jet, K-LPHD(charged)=N-hadrons(charged)/N-partons=0.56+/-0.10
Near and far- infrared absorption and electronic structure of Ge-SiGe Multi Quantum Wells
Search for a W(') boson decaying to a top and bottom quark pair in 1.8 TeV p(p)over-bar collisions
We report the results of a search for a W(') boson produced in p (p)
over bar collisions at a center-of-mass energy of 1.8 TeV using a 106
pb(-1) data sample recorded by the Collider Detector at Fermilab. We
observe no significant excess of events above background for a W(')
boson decaying to a top and bottom quark pair. In a model where this
boson would mediate interactions involving a massive right-handed
neutrino (nu(R)) and have standard model strength couplings, we use
these data to exclude a W(') boson with mass between 225 and 536
GeV/c(2) at 95\% confidence level for M(W)(')>M(nuR) and between 225 and
566 GeV/c(2) at 95\% confidence level for M(W)(')<M(nuR)
Search for the supersymmetric partner of the top quark in dilepton events from p(p)over-bar collisions at root s=1.8 TeV
We have searched for the supersymmetric partner of the top quark (stop) in
107 pb^{-1} of p-pbar collisions at \sqrt{s}= 1.8 TeV collected by the Collider
Detector at Fermilab (CDF). Within the framework of the Minimal Supersymmetric
extension of the Standard Model (MSSM) each of the pair-produced stops is
assumed to decay into a lepton, bottom quark and supersymmetric neutrino. Such
a scenario would give rise to events with two leptons, two hadronic jets, and a
substantial imbalance of transverse energy. No evidence of such a stop signal
has been found. We calculate a 95% confidence level (C.L.) upper limit on the
stop production cross section, which excludes stop masses in the region
(80<m_{\stop}<135 GeV/c^2) in the mass plane of stop versus sneutrino.Comment: 7 pages, 5 figures. Submitted to Physical Review Letter
Search for associated production of Upsilon and vector boson in p(p)over-bar collisions at root(s)over-bar=1.8 TeV
We present a search for associated production of the Y(1S) and a vector boson in 83 pb(-1) of p (p) over bar collisions at roots=1.8 TeV collected by the CDF experiment in 1994-1995. We find no evidence of the searched signal in the data, and set upper limits to the production cross sections