46 research outputs found
Global QCD Analysis and the CTEQ Parton Distributions
The CTEQ program for the determination of parton distributions through a
global QCD analysis of data for various hard scattering processes is fully
described. A new set of distributions, CTEQ3, incorporating several new types
of data is reported and compared to the two previous sets of CTEQ
distributions. Comparison with current data is discussed in some detail. The
remaining uncertainties in the parton distributions and methods to further
reduce them are assessed. Comparisons with the results of other global analyses
are also presented.Comment: (Change in Latex style only: 2up style removed since many don't have
it.) 35 pages, 23 figures separately submitted as uuencoded compressed
ps-file; Michigan State Report # MSU-HEP/41024 and CTEQ 40
Cichlid biogeography: comment and review
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72313/1/j.1467-2979.2004.00148.x.pd
Measurement of the ratio of the +-jet cross section to the inclusive +jets cross section
We present a measurement of the fraction of inclusive +jets events
produced with net charm quantum number , denoted +-jet, in
collisions at TeV using approximately 1~fb of
data collected by the D0 detector at the Fermilab Tevatron Collider. We
identify the +jets events via the leptonic boson decays. Candidate
+-jet events are selected by requiring a jet containing a muon in
association with a reconstructed boson and exploiting the charge
correlation between this muon and boson decay lepton to perform a nearly
model-independent background subtraction. We measure the fraction of
+-jet events in the inclusive +jets sample for jet GeV and
pseudorapidity to be
0.074(stat.)(syst.), in agreement with
theoretical predictions. The probability that background fluctuations could
produce the observed fraction of +-jet events is estimated to be
, which corresponds to a 3.5 statistical
significance.Comment: submitted to Physics Letters
FIRST SEARCHES FOR OPTICAL COUNTERPARTS TO GRAVITATIONAL-WAVE CANDIDATE EVENTS
During the LIGO and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type