1,242 research outputs found
Search for a Technicolor omega_T Particle in Events with a Photon and a b-quark Jet at CDF
If the Technicolor omega_T particle exists, a likely decay mode is omega_T ->
gamma pi_T, followed by pi_T -> bb-bar, yielding the signature gamma bb-bar. We
have searched 85 pb^-1 of data collected by the CDF experiment at the Fermilab
Tevatron for events with a photon and two jets, where one of the jets must
contain a secondary vertex implying the presence of a b quark. We find no
excess of events above standard model expectations. We express the result of an
exclusion region in the M_omega_T - M_pi_T mass plane.Comment: 14 pages, 2 figures. Available from the CDF server (PS with figs):
http://www-cdf.fnal.gov/physics/pub98/cdf4674_omega_t_prl_4.ps
FERMILAB-PUB-98/321-
Measurement of the B0 anti-B0 oscillation frequency using l- D*+ pairs and lepton flavor tags
The oscillation frequency Delta-md of B0 anti-B0 mixing is measured using the
partially reconstructed semileptonic decay anti-B0 -> l- nubar D*+ X. The data
sample was collected with the CDF detector at the Fermilab Tevatron collider
during 1992 - 1995 by triggering on the existence of two lepton candidates in
an event, and corresponds to about 110 pb-1 of pbar p collisions at sqrt(s) =
1.8 TeV. We estimate the proper decay time of the anti-B0 meson from the
measured decay length and reconstructed momentum of the l- D*+ system. The
charge of the lepton in the final state identifies the flavor of the anti-B0
meson at its decay. The second lepton in the event is used to infer the flavor
of the anti-B0 meson at production. We measure the oscillation frequency to be
Delta-md = 0.516 +/- 0.099 +0.029 -0.035 ps-1, where the first uncertainty is
statistical and the second is systematic.Comment: 30 pages, 7 figures. Submitted to Physical Review
Measurement of the Dipion Mass Spectrum in X(3872) -> J/Psi Pi+ Pi- Decays
We measure the dipion mass spectrum in X(3872)--> J/Psi Pi+ Pi- decays using
360 pb-1 of pbar-p collisions at 1.96 TeV collected with the CDF II detector.
The spectrum is fit with predictions for odd C-parity (3S1, 1P1, and 3DJ)
charmonia decaying to J/Psi Pi+ Pi-, as well as even C-parity states in which
the pions are from Rho0 decay. The latter case also encompasses exotic
interpretations, such as a D0-D*0Bar molecule. Only the 3S1 and J/Psi Rho
hypotheses are compatible with our data. Since 3S1 is untenable on other
grounds, decay via J/Psi Rho is favored, which implies C=+1 for the X(3872).
Models for different J/Psi-Rho angular momenta L are considered. Flexibility in
the models, especially the introduction of Rho-Omega interference, enable good
descriptions of our data for both L=0 and 1.Comment: 7 pages, 4 figures -- Submitted to Phys. Rev. Let
Search for New Particles Decaying to top-antitop in proton-antiproton collisions at squareroot(s)=1.8 TeV
We use 106 \ipb of data collected with the Collider Detector at Fermilab to
search for narrow-width, vector particles decaying to a top and an anti-top
quark. Model independent upper limits on the cross section for narrow, vector
resonances decaying to \ttbar are presented. At the 95% confidence level, we
exclude the existence of a leptophobic \zpr boson in a model of
topcolor-assisted technicolor with mass M_{\zpr} 480 \gev for natural
width = 0.012 M_{\zpr}, and M_{\zpr} 780 \gev for =
0.04 M_{\zpr}.Comment: The CDF Collaboration, submitted to PRL 25-Feb-200
A Measurement of the Differential Dijet Mass Cross Section in p-pbar Collisions at sqrt{s}=1.8 TeV
We present a measurement of the cross section for production of two or more
jets as a function of dijet mass, based on an integrated luminosity of 86 pb^-1
collected with the Collider Detector at Fermilab. Our dijet mass spectrum is
described within errors by next-to-leading order QCD predictions using CTEQ4HJ
parton distributions, and is in good agreement with a similar measurement from
the D0 experiment.Comment: 18 pages including 2 figures and 3 tables. Submitted to Phys. Rev. D
Rapid Communication
Search for Higgs Boson Decaying to b-bbar and Produced in Association with W Bosons in p-pbar Collisions at sqrt{s}=1.96 TeV
We present a search for Higgs bosons decaying into b-bbar and produced in
association with W bosons in p-pbar collisions at sqrt{s}=1.96 TeV. This search
uses 320 pb-1 of the dataset accumulated by the upgraded Collider Detector at
Fermilab. Events are selected that have a high-transverse momentum electron or
muon, missing transverse energy, and two jets, one of which is consistent with
a hadronization of a b quark. Both the number of events and the dijet mass
distribution are consistent with standard model background expectations, and we
set 95% confidence level upper limits on the production cross section times
branching ratio for the Higgs boson or any new particle with similar decay
kinematics. These upper limits range from 10 pb for mH=110 GeV/c2 to 3 pb for
mH=150 GeV/c2.Comment: 7 pages, 3 figures; updated title to published versio
Search for Second-Generation Scalar Leptoquarks in Collisions at =1.96 TeV
Results on a search for pair production of second generation scalar
leptoquark in collisions at =1.96 TeV are reported. The
data analyzed were collected by the CDF detector during the 2002-2003 Tevatron
Run II and correspond to an integrated luminosity of 198 pb. Leptoquarks
(LQ) are sought through their decay into (charged) leptons and quarks, with
final state signatures represented by two muons and jets and one muon, large
transverse missing energy and jets. We observe no evidence for production
and derive 95% C.L. upper limits on the production cross sections as well
as lower limits on their mass as a function of , where is the
branching fraction for .Comment: 9 pages (3 author list) 5 figure
Measurement of the Inclusive Jet Cross Section using the Kt algorithm in pp-bar Collisions at sqrt(s) = 1.96 TeV
We report on a measurement of the inclusive jet production cross section in
pp-bar collisions at sqrt{s} = 1.96 TeV using data collected with the upgraded
Collider Detector at Fermilab in Run II (CDF II) corresponding to an integrated
luminosity of 385 pb^-1. Jets are reconstructed using the kt algorithm. The
measurement is carried out for jets with rapidity 0.1 < | yjet | < 0.7 and
transverse momentum in the range 54 < ptjet < 700 GeV/c. The measured cross
section is in good agreement with next-to-leading order perturbative QCD
predictions after the necessary non-perturbative parton-to-hadron corrections
are included.Comment: Submitted to Phys. Rev. Let
Search for anomalous semileptonic decay of heavy flavor hadrons produced in association with a W boson at CDF II
We present a search for anomalous semileptonic decays of heavy flavor hadrons
produced in association with a boson, in proton-antiproton collisions at
sqrt{s}=1.96 TeV. We use 162 pb-1 of data collected with the CDF II detector at
the Fermilab Tevatron Collider. We select events with one W boson and at least
one jet with an identified secondary vertex. In the jets with a secondary
vertex we look for a semileptonic decay to a muon. We compare the number of
jets with both a secondary vertex and a semileptonic decay, and the kinematic
properties of these jets, with the standard model expectation of W plus heavy
flavor production and decay. No discrepancy is seen between the observation and
the expectation, and we set limits on the production cross section of a B-like
hadron with an anomalously high semileptonic branching ratio.Comment: 8 pages, 2 figures, submitted to PRD-RC; replaced to adjust the page
forma
Osteochondral transplantation using autografts from the upper tibio-fibular joint for the treatment of knee cartilage lesions
Purpose Treatment of large cartilage lesions of the knee
in weight-bearing areas is still a controversy and challenging topic. Autologous osteochondral mosaicplasty has
proven to be a valid option for treatment but donor site
morbidity with most frequently used autografts remains a
source of concern. This study aims to assess clinical results
and safety profile of autologous osteochondral graft from
the upper tibio-fibular joint applied to reconstruct symptomatic osteochondral lesions of the knee.
Methods Thirty-one patients (22 men and 9 women) with
grade 4 cartilage lesions in the knee were operated by
mosaicplasty technique using autologous osteochondral
graft from the upper tibio-fibular joint, between 1998 and
2006. Clinical assessment included visual analog scale
(VAS) for pain and Lysholm score. All patients were
evaluated by MRI pre- and post-operatively regarding joint
congruency as good, fair (inferior to 1 mm incongruence),
and poor (incongruence higher than 1 mm registered in any
frame). Donor zone status was evaluated according to
specific protocol considering upper tibio-fibular joint
instability, pain, neurological complications, lateral collateral ligament insufficiency, or ankle complaints.
Results Mean age at surgery was 30.1 years (SD 12.2). In
respect to lesion sites, 22 were located in weight-bearing
area of medial femoral condyle, 7 in lateral femoral condyle, 1 in trochlea, and 1 in patella. Mean follow-up was
110.1 months (SD 23.2). Mean area of lesion was 3.3 cm
2
(SD 1.7), and a variable number of cylinders were used,
mean 2.5 (SD 1.3). Mean VAS score improved from 47.1
(SD 10.1) to 20.0 (SD 11.5); p = 0.00. Similarly, mean
Lysholm score increased from 45.7 (SD 4.5) to 85.3
(SD 7.0); p = 0.00. The level of patient satisfaction was
evaluated, and 28 patients declared to be satisfied/very
satisfied and would do surgery again, while 3 declared as
unsatisfied with the procedure and would not submit to
surgery again. These three patients had lower clinical scores
and kept complaints related to the original problem but
unrelated to donor zone. MRI score significantly improved
at 18–24 months comparing with pre-operative (p = 0.004).
No radiographic or clinical complications related to donor
zone with implication in activity were registered.
Conclusions This work corroborates that mosaicplasty
technique using autologous osteochondral graft from the
upper tibio-fibular joint is effective to treat osteochondral
defects in the knee joint. No relevant complications related
to donor zone were registered
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