10,959 research outputs found
Studies of Higher Twist and Higher Order Effects in NLO and NNLO QCD Analysis of Lepton-Nucleon Scattering Data on F_2 and R =sigma_L/sigma_T
We report on the extraction of the higher twist contributions to F_2 and R =
sigma_L/sigma_T from the global NLO and NNLO QCD fits to lepton nucleon
scattering data over a wide range of Q^2. The NLO fits require both target mass
and higher twist contributions at low Q^2. However, in the NNLO analysis, the
data are described by the NNLO QCD predictions (with target mass corrections)
without the need for any significant contributions from higher twist effects.
An estimate of the difference between NLO and NNLO parton distribution
functions is obtained.Comment: 5 pages, 6 figures, submitted to Eur. Phys.
Electroweak precision measurements with the CMS detector
We report on a precision measurement of the effective weak mixing angle using
the forward-backward asymmetry of Drell-Yan ( and ) events in pp
collisions at at CMS. The data sample corresponds to
an integrated luminosity of and
for muon and electron channels, respectively. The sample consists of 8.2
million dimuon and 4.9 million dielectron events. With new analysis techniques
and large samples the statistical and systematic uncertainties are reduced by a
factor of two compared to previous measurements at the LHC. The extracted value
of the effective weak mixing angle from the combined and data
samples is or .Comment: 6 pages 2 figures. To be published in Proceeding of EPS 2017, Lido,
Ital
Standard Model Precision Electroweak Measurements at HL-LHC and Future Hadron Colliders
We investigate the uncertainties for current and future measurements of
electroweak (EW) parameters at hadron colliders. These include the measurement
of the mass of the top quark (), the direct measurement of the mass of the
W boson (), the measurement of the effective EW mixing angle
(M), and the measurement of the on-shell
EW mixing angle which is equivalent to an
indirect measurement of the W mass (). Reduction of a factor of
2 to 3 in the measurement errors is expected in the future.Comment: Talk presented CIPANP2015. 13 pages, LaTeX, 5 pdf figures,, 3 Table
Resolving the Axial Mass Anomaly in neutrino Scattering
We present a parametrization of the observed enhancement in the transverse
electron quasielastic (QE) response function for nucleons bound in carbon as a
function of the square of the four momentum transfer (Q2) in terms of a
correction to the magnetic form factors of bound nucleons. The parametrization
should also be applicable to the transverse cross section in neutrino
scattering. If the transverse enhancement originates from meson exchange
currents (MEC), then it is theoretically expected that any enhancement in the
longitudinal or axial contributions is small. We present the predictions of the
"Transverse Enhancement" model (which is based on electron scattering data
only) for the neutrino and anti-neutrino differential and total QE cross
sections for nucleons bound in carbon. The 2Q2 dependence of the transverse
enhancement is observed to resolve much of the long standing discrepancy
("Axial Mass Anomaly}) in the QE total cross sections and differential
distributions between low energy and high energy neutrino experiments on
nuclear targets.Comment: 3 pages, 3 Figures, Presented by Arie Bodek at the 19th Particles and
Nuclei International Conference, PANIC 2011, MIT, Cambridge, MA July 201
- …
