43 research outputs found
Drell-Yan diffraction: breakdown of QCD factorisation
We consider the diffractive Drell-Yan process in proton-(anti)proton
collisions at high energies in the color dipole approach. The calculations are
performed at forward rapidities of the leptonic pair. Effect of eikonalization
of the universal "bare"dipole-target elastic amplitude in the saturation regime
takes into account the principal part of the gap survival probability. We
present predictions for the total and differential cross sections of the single
diffractive lepton pair production at RHIC and LHC energies. We analyze
implications of the QCD factorisation breakdown in the diffractive Drell-Yan
process, which is caused by a specific interplay of the soft and hard
interactions, and resulting in rather unusual properties of the corresponding
observables.Comment: 19 pages, 7 figure
The fully differential single-top-quark cross section in next-to-leading order QCD
We present a new next-to-leading order calculation for fully differential
single-top-quark final states. The calculation is performed using phase space
slicing and dipole subtraction methods. The results of the methods are found to
be in agreement. The dipole subtraction method calculation retains the full
spin dependence of the final state particles. We show a few numerical results
to illustrate the utility and consistency of the resulting computer
implementations.Comment: 37 pages, latex, 2 ps figure
Heavy-quark mass dependence in global PDF analyses and 3- and 4-flavour parton distributions
We study the sensitivity of our recent MSTW 2008 NLO and NNLO PDF analyses to
the values of the charm- and bottom-quark masses, and we provide additional
public PDF sets for a wide range of these heavy-quark masses. We quantify the
impact of varying m_c and m_b on the cross sections for W, Z and Higgs
production at the Tevatron and the LHC. We generate 3- and 4-flavour versions
of the (5-flavour) MSTW 2008 PDFs by evolving the input PDFs and alpha_S
determined from fits in the 5-flavour scheme, including the eigenvector PDF
sets necessary for calculation of PDF uncertainties. As an example of their
use, we study the difference in the Z total cross sections at the Tevatron and
LHC in the 4- and 5-flavour schemes. Significant differences are found,
illustrating the need to resum large logarithms in Q^2/m_b^2 by using the
5-flavour scheme. The 4-flavour scheme is still necessary, however, if cuts are
imposed on associated (massive) b-quarks, as is the case for the experimental
measurement of Z b bbar production and similar processes.Comment: 40 pages, 11 figures. Grids can be found at
http://projects.hepforge.org/mstwpdf/ and in LHAPDF V5.8.4. v2: version
published in EPJ
Measurement of single pi0 production in neutral current neutrino interactions with water by a 1.3 GeV wide band muon neutrino beam
Neutral current single pi0 production induced by neutrinos with a mean energy
of 1.3 GeV is measured at a 1000 ton water Cherenkov detector as a near
detector of the K2K long baseline neutrino experiment. The cross section for
this process relative to the total charged current cross section is measured to
be 0.064 +- 0.001 (stat.) +- 0.007 (sys.). The momentum distribution of
produced pi0s is measured and is found to be in good agreement with an
expectation from the present knowledge of the neutrino cross sections.Comment: 6 pages, 4 figures, Submitted to Phys. Lett.
Photoproduction of mesons associated with a leading neutron
The photoproduction of mesons associated with a leading
neutron has been observed with the ZEUS detector in collisions at HERA
using an integrated luminosity of 80 pb. The neutron carries a large
fraction, {}, of the incoming proton beam energy and is detected at
very small production angles, { mrad}, an indication of
peripheral scattering. The meson is centrally produced with
pseudorapidity {
GeV}, which is large compared to the average transverse momentum of the neutron
of 0.22 GeV. The ratio of neutron-tagged to inclusive production is
in the photon-proton
center-of-mass energy range { GeV}. The data suggest that the
presence of a hard scale enhances the fraction of events with a leading neutron
in the final state.Comment: 28 pages, 4 figures, 2 table
Measurement of the Neutron Spin Structure Function with a Polarized ^3He Target
Results are reported from the HERMES experiment at HERA on a measurement of
the neutron spin structure function in deep inelastic scattering
using 27.5 GeV longitudinally polarized positrons incident on a polarized
He internal gas target. The data cover the kinematic range
and . The integral evaluated at a fixed of is . Assuming Regge behavior at low , the first
moment is .Comment: 4 pages TEX, text available at
http://www.krl.caltech.edu/preprints/OAP.htm
Measurement of the Isolated Photon Cross Section in p-pbar Collisions at sqrt{s}=1.96 TeV
The cross section for the inclusive production of isolated photons has been
measured in p anti-p collisions at sqrt{s}=1.96 TeV with the D0 detector at the
Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV
and have pseudorapidity |eta|<0.9. The cross section is compared with the
results from two next-to-leading order perturbative QCD calculations. The
theoretical predictions agree with the measurement within uncertainties.Comment: 7 pages, 5 figures, submitted to Phys.Lett.
US hegemony and the origins of Japanese nuclear power : the politics of consent
This paper deploys the Gramscian concepts of hegemony and consent in order to explore the process whereby nuclear power was brought to Japan. The core argument is that nuclear power was brought to Japan as a consequence of US hegemony. Rather than a simple manifestation of one state exerting material ‘power over' another, bringing nuclear power to Japan involved a series of compromises worked out within and between state and civil society in both Japan and the USA. Ideologies of nationalism, imperialism and modernity underpinned the process, coalescing in post-war debates about the future trajectory of Japanese society, Japan's Cold War alliance with the USA and the role of nuclear power in both. Consent to nuclear power was secured through the generation of a psychological state in the public mind combining the fear of nuclear attack and the hope of unlimited consumption in a nuclear-fuelled post-modern world
Love to win or hate to lose? Asymmetry of dopamine D2 receptor binding predicts sensitivity to reward vs. punishment
Humans show consistent differences in the extent to which their behavior reflects a bias towards appetitive approach-related behavior or avoidance of aversive stimuli (Elliot, 2008). We examined the hypothesis that in healthy subjects this motivational bias (assessed by self-report and by a probabilistic learning task that allows direct comparison of the relative sensitivity to reward and punishment) reflects lateralization of dopamine signaling. Using [F-18]fallypride to measure D2/D3 binding , we found that self-reported motivational bias was predicted by the asymmetry of frontal D2 binding. Similarly, striatal and frontal asymmetries in D2 dopamine receptor binding, rather than absolute binding levels, predicted individual differences in learning from reward vs. punishment. These results suggest that normal variation in asymmetry of dopamine signaling may, in part, underlie human personality and cognition