3,588 research outputs found
Recent QCD results from the Tevatron
Recent QCD related results from the CDF and the D0 experiments are presented
based on proton anti-proton collision data at sqrt(s)=1.96 TeV, taken in Run II
of the Fermilab Tevatron Collider. Measured observables include inclusive
photon and diphoton production, vector boson plus jets production, event shape
variables, and inclusive multijet production. The measurement results are
compared to QCD theory calculations in different approximations. A
determination of the strong coupling constant from jet data is presented.Comment: 12 pages with 14 figures, to appear in the proceedings of the
"Ringberg Workshop: New Trends in HERA Physics 2011", Ringberg Castle,
Germany, 25-28 September, 201
Background dependence of dimuon asymmetry in interactions at TeV
The D0 Collaboration has reported an anomalous charge asymmetry in the
production of same-sign muon pairs at the Fermilab Tevatron. The magnitude of
this effect depends on the subtraction of several backgrounds, the most notable
of which is due to kaons being misidentified as muons either through decays in
flight or punch-through. The present authors suggested a check on such
backgrounds consisting of a tight restriction on the muon impact parameter ,
to confirm that this excess was indeed due to meson decays. The D0
Collaboration has performed a related check applying transverse impact
parameter (IP) restrictions, whose implications are discussed. We study
background asymmetry predictions for events involving two muons with IP bounds
which are complementary to each other. These predictions may be used in future
measurements of the net charge asymmetry from decays.Comment: To be published in Physics Letters
Next-to-next-to-next-to-leading-order soft-gluon corrections in hard-scattering processes near threshold
I present a unified calculation of soft-gluon corrections to hard-scattering
cross sections through next-to-next-to-next-to-leading order (NNNLO). Master
formulas are derived, from a threshold resummation formalism, that can be
applied to total and differential cross sections for hard-scattering processes
in hadron colliders. I also present numerical results for charged Higgs
production at the LHC where these corrections are large, and for top quark
production at the Tevatron where these corrections greatly reduce the scale
dependence of the cross section.Comment: 22 pages, 3 figure
CP parameters of the B systems from Tevatron
Recent results on CP parameters of the B systems obtained by the CDF and D0
collaborations using the data samples collected at the Tevatron Collider in the
period 2002 - 2007 were presented at the QCD 2008 conference (Montpellier,
France). These results include measurements of the mixing phase, decay width
difference, and CP violation parameters in the Bs and Bu decays.Comment: Presented at the QCD 2008 Conference (Montpellier, France); added
references; corrected RCP+ paramete
The like-sign dimuon charge asymmetry in SUSY models
We study the new physics (NP) implications of the recently reported 3.2 sigma
Standard Model (SM) deviation in the like-sign dimuon asymmetry at the
Tevatron. Assuming that new physics only enters the B(s) mixing amplitude we
explore the implications for generic new physics, general supersymmetric (SUSY)
models and also SUSY SU(5). In the case of SUSY SU(5) we exploit the GUT scale
relationship between slepton and squark soft masses to predict rates for lepton
flavour violation (LFV). The predicted rates for tau --> mu + gamma are found
to be detectable at future Super-B factories.Comment: 4 pages, 4 eps figures, version accepted for publicatio
W/Z + jet production at the Tevatron
Vector boson plus jet production is interesting for Higgs search, beyond the
Standard Model physics and provides standard candles for calibration. This is
complementary to inclusive jet production measurements which provide precision
tests of perturbative QCD. A multitude of W/Z plus heavy and light flavour jet
measurements in ppbar collisions at a centre of mass energy of sqrt{s}=1.96TeV
is discussed. Next-to-Leading order perturbative QCD predictions and various
models are compared to the measurements.Comment: 4 pages, 1 figur
Independent measurement of the top quark mass and the light- and bottom-jet energy scales at hadron colliders
A method for the simultaneous determination of the energy scales for b-quark
jets and light jets, the jet energy resolution, and the top quark mass at
hadron colliders is presented. The method exploits the unique kinematics of
events with top-antitop pair production, where one of the top quarks involves a
leptonic and one a hadronic W boson decay. The paper shows a feasibility study
of how this simultaneous measurement can be performed at the upcoming LHC
experiments ATLAS and CMS.Comment: 10 pages, 5 figure
Angular distribution of Drell-Yan process at hadron colliders to NLO-QCD in models of TeV scale gravity
In TeV scale gravity models, for dilepton production at hadron colliders, we
present the NLO-QCD corrections for the double differential cross section in
the invariant mass and scattering angle. For both ADD and RS models, the
quantitative impact of QCD corrections for extra dimension searches at LHC and
Tevatron are investigated. We present the K-factors for both ADD and RS models
at LHC and Tevatron. Inclusion of QCD corrections to NLO stabilises the cross
section with respect to scale variations.Comment: 35 pages, 12 figures, version to appear in NP
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