139 research outputs found
Measurement of direct photon production at Tevatron fixed target energies
Measurements of the production of high transverse momentum direct photons by
a 515 GeV/c piminus beam and 530 and 800 GeV/c proton beams in interactions
with beryllium and hydrogen targets are presented. The data span the kinematic
ranges of 3.5 < p_T < 12 GeV/c in transverse momentum and 1.5 units in
rapidity. The inclusive direct-photon cross sections are compared with
next-to-leading-order perturbative QCD calculations and expectations based on a
phenomenological parton-k_T model.Comment: RevTeX4, 23 pages, 32 figures, submitted to Phys. Rev.
Increased maternal and fetal cholesterol efflux capacity and placental cyp27a1 expression in pre-eclampsia
Preeclampsia is a pregnancy-specific condition that leads to increased cardiovascular risk in later life. A decrease in cholesterol efflux capacity is linked to CVD. We hypothesized that in preeclampsia there would be a disruption of maternal/fetal plasma to efflux cholesterol, as well as differences in the concentrations of both placental sterol 27-hydroxylase (CYP27A1) and apoA1 binding protein (AIBP). Total, HDL-, and ABCA1-mediated cholesterol effluxes were performed with maternal and fetal plasma from women with preeclampsia and normotensive controls (both n = 17). apoA1 and apoE were quantified by chemiluminescence, and 27-hydroxycholesterol (27-OHC) by GC-MS. Immunohistochemistry was used to determine placental expression/localization of CYP27A1, AIBP, apoA1, apoE, and SRB1. Maternal and fetal total and HDL-mediated cholesterol efflux capacities were increased in preeclampsia (by 10â20%), but ABCA1-mediated efflux was decreased (by 20â35%; P < 0.05). Maternal and fetal apoE concentrations were higher in preeclampsia. Fetal plasma 27-OHC levels were decreased in preeclamptic samples (P < 0.05). Placental protein expression of both CYP27A1 and AIBP were localized around fetal vessels and significantly increased in preeclampsia (P = 0.04). Placental 27-OHC concentrations were also raised in preeclampsia (P < 0.05). Increased HDL-mediated cholesterol efflux capacity and placental CYP27A1/27-OHC could be a rescue mechanism in preeclampsia, to remove cholesterol from cells to limit lipid peroxidation and increase placental angiogenesis
Evidence for Parton kT Effects in High pT Particle Production
Inclusive pizero and direct-photon cross sections in the kinematic range 3.5
< pT < 12 GeV/c with central rapidities are presented for 530 and 800 GeV/c
proton beams and a 515 GeV/c pi- beam incident on beryllium targets. Current
Next-to-Leading-Order perturbative QCD calculations fail to adequately describe
the data for conventional choices of scales. Kinematic distributions from these
hard scattering events provide evidence that the interacting partons carry
significant initial-state parton transverse momentum (kT). Incorporating these
kT effects phenomenologically greatly improves the agreement between
calculations and the measured cross sections.Comment: 11 pages including 6 pages of figures with caption
Production of pizero and eta mesons at large transverse momenta in pi-p and pi-Be interactions at 515 GeV/c
We present results on the production of high transverse momentum pizero and
eta mesons in pi-p and pi-Be interactions at 515 GeV/c. The data span the
kinematic ranges 1 < p_T < 11 GeV/c in transverse momentum and -0.75 < y < 0.75
in rapidity. The inclusive pizero cross sections are compared with
next-to-leading order QCD calculations and to expectations based on a
phenomenological parton-k_T model.Comment: RevTeX4, 15 pages, 15 figures, to be submitted to Phys. Rev.
Inclusive jet cross section in collisions at TeV
The inclusive jet differential cross section has been measured for jet
transverse energies, , from 15 to 440 GeV, in the pseudorapidity region
0.10.7. The results are based on 19.5 pb of data
collected by the CDF collaboration at the Fermilab Tevatron collider. The data
are compared with QCD predictions for various sets of parton distribution
functions. The cross section for jets with GeV is significantly
higher than current predictions based on O() perturbative QCD
calculations. Various possible explanations for the high- excess are
discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review
Letter
Search for charged Higgs decays of the top quark using hadronic tau decays
We present the result of a search for charged Higgs decays of the top quark,
produced in collisions at 1.8 TeV. When the charged
Higgs is heavy and decays to a tau lepton, which subsequently decays
hadronically, the resulting events have a unique signature: large missing
transverse energy and the low-charged-multiplicity tau. Data collected in the
period 1992-1993 at the Collider Detector at Fermilab, corresponding to
18.70.7~pb, exclude new regions of combined top quark and charged
Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp;
submitted to Phys. Rev.
Measurement of Dijet Angular Distributions at CDF
We have used 106 pb^-1 of data collected in proton-antiproton collisions at
sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular
distributions in events with two jets in the final state. The angular
distributions agree with next to leading order (NLO) predictions of Quantum
Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at
95% confidence level (CL) a model of quark substructure in which only up and
down quarks are composite and the contact interaction scale is Lambda_ud(+) <
1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are
composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6
TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to
Physical Review Letters on September 17, 1996. Postscript file of full paper
available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p
Search for New Particles Decaying to Dijets at CDF
We have used 106 pb^-1 of data collected with the Collider Detector at
Fermilab to search for new particles decaying to dijets. We exclude at the 95%
confidence level models containing the following new particles: axigluons and
flavor universal colorons with mass between 200 and 980 GeV/c, excited quarks
with mass between 80 and 570 GeV/c^2 and between 580 and 760 GeV/c^2, color
octet technirhos with mass between 260 and 480 GeV/c^2, W' bosons with mass
between 300 and 420 GeV/c^2, and E_6 diquarks with mass between 290 and 420
GeV/c^2.Comment: 18 pages, 4 figures, 1 table. Submitted to Physical Review D Rapid
Communications. Postscript file of paper is also available at
http://www-cdf.fnal.gov/physics/pub97/cdf3276_dijet_search_prd_rc.p
Hadroproduction of Ïc states in 530 GeV/c Ïâ interactions with nuclear targets
We are studying production of Ïc states in 530 GeV/c Ïâ interactions with several targets. Ïc mesons are observed in the mode (ÏâJ/Ï+Îł). Only photons that converted to e+eâ pairs are used in the reconstruction of the Ïc mesons. Preliminary analysis shows that the fraction of observed J/Ïs coming from Ïc radiative decays is 0.44±0.09±0.08, and that the relative production rate of Ïc1 to Ïc2 is 1.3±0.6.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87707/2/1062_1.pd
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