27 research outputs found
Aspects of four-jet production in polarized proton-proton collisions
We examine the intrinsic spin-dependence of the dominant subprocess contribution to four-jet production in polarized proton-proton
collisions using helicity amplitude techniques. We find that the partonic
level, longitudinal spin-spin asymmetry, , is intrinsically large
in the kinematic regions probed in experiments detecting four isolated jets.
Such events may provide another qualitative or semi-quantitative test of the
spin-structure of QCD in planned polarized collisions at RHIC.Comment: 9 pages, LaTeX, 2 uuencoded postscript files attache
Enhancing the top signal at Tevatron using Neural Nets
We show that Neural Nets can be useful for top analysis at Tevatron. The main
features of and background events on a mixed sample are projected in
a single output, which controls the efficiency and purity of the
signal.Comment: 11 pages, 6 figures (not included and available from the authors),
Latex, UB-ECM-PF 94/1
Coloron Phenomenology
A flavor-universal extension of the strong interactions was recently proposed
in response to the apparent excess of high- jets in the inclusive jet
spectrum measured at the Tevatron. This paper studies the color octet of
massive gauge bosons (`colorons') that is present in the low-energy spectrum of
the model's Higgs phase. Constraints from searches for new particles decaying
to dijets and from measurements of the weak-interaction parameter imply
that the colorons must have masses greater than 870-1000 GeV. The implications
of recent Tevatron data and the prospective input from future experiments are
also discussed.Comment: 13 pages, 4 embedded Postscript figures, LaTeX, full postscript
version also available at http://smyrd.bu.edu/htfigs/htfigs.html rectified
confusing phrase at end of sub-section on 'dijets
Spin-dependent Parton Distributions from Polarized Structure Function Data
In the past year, polarized deep inelastic scattering experiments at CERN and
SLAC have obtained structure function measurements off proton, neutron and
deuteron targets at a level of precision never before achieved. The
measurements can be used to test the Bjorken and Ellis-Jaffe sum rules, and
also to obtain information on the parton distributions in polarized nucleons.
We perform a global leading-order QCD fit to the proton deep inelastic data in
order to extract the spin-dependent parton distributions. By using parametric
forms which are consistent with theoretical expectations at large and small
, we find that the quark distributions are now rather well constrained. We
assume that there is no significant intrinsic polarization of the strange quark
sea. The data are then consistent with a modest amount of the proton's spin
carried by the gluon, although the shape of the gluon distribution is not well
constrained, and several qualitatively different shapes are suggested. The
spin-dependent distributions we obtain can be used as input to phenomenological
studies for future polarized hadron-hadron and lepton-hadron colliders.Comment: 23 pages, DTP/94/3
Neural network analysis for gamma gamma -> 3pi at Daphne
We consider the possibility of using neural networks in experimental data
analysis in Daphne. We analyze the process
and its backgrounds using neural networks and we compare their performances
with traditional methods of applying cuts on several kinematical variables. We
find that the neural networks are more efficient and can be of great help for
processes with small number of produced events.Comment: 11 pages, latex, 2 figures
W and Z Polarization Effects in Hadronic Collisions
A Monte Carlo study of the polar and azimuthal angular distributions of the
lepton pair arising from the decay of a or boson produced at high
transverse momentum in hadronic collisions is presented. In the absence of cuts
on the final state leptons, the lepton angular distribution in the gauge boson
rest frame is determined by the gauge boson polarization. Numerical results for
the lepton angular distributions in the Collins--Soper frame with acceptance
cuts and energy resolution smearing applied to the leptons are presented. In
the presence of cuts, the lepton angular distributions are dominated by
kinematic effects rather than polarization effects, however, some polarization
effects are still observable on top of the kinematic effects. Polarization
effects are highlighted when the experimental distributions are divided by the
Monte Carlo distributions obtained using isotropic gauge boson decay.Comment: 23 pages (LaTeX) plus 13 postscript figures, MAD/PH/834, UCD--94--23.
Figures are available from the authors or as a compressed tar file via
anonymous ftp at phenom.physics.wisc.edu in directory
~pup/preprints/madph-94-834-figs.tar.
Next-to-Leading Order Cross Sections for Tagged Reactions
We extend the phase space slicing method of Giele, Glover and Kosower for
performing next-to-leading order jet cross section calculations in two
important ways: we show how to include fragmentation functions and how to
include massive particles. These extensions allow the application of this
method to not just jet cross sections but also to cross sections in which a
particular final state particle, including a or -meson, is tagged.Comment: 36 pages, Latex Small corrections to text. To appear in Phys. Rev.
What We Can Learn About Nucleon Spin Structure From Recent Data
We have used recent polarized deep-inelastic scattering data from CERN and
SLAC to extract information about nucleon spin structure. We find that the SMC
proton data, the E142 neutron data and the deuteron data from SMC and E143 give
different results for fractions of the spin carried by each of the
constituents. These appear to lead to two different and incompatible models for
the polarized strange sea. The polarized gluon distribution occuring in the
gluon anomaly does not have to be large in order to be consistent with either
set of experimental data. However, it appears that the discrepancies in the
implications of these data cannot be resolved with any simple theoretical
arguments. We conclude that more experiments must be performed in order to
adequately determine the fraction of spin carried by each of the nucleon
constituents.Comment: 23 page
Aspects of and Production in Polarized Proton-Proton Collisions
Several topics of relevance to low transverse momentum and
production in polarized proton-proton collisions
are discussed. The leading contributions to the low
production cross-sections via , , and
initial states are calculated as well as the corresponding spin-spin
asymmetries. We find that production increases relative to direct
and production, providing up to of the observable
pairs arising from decays in collisions at . The spin-dependence of production, however, is much smaller
than for either direct or production and so will likely be far
less useful than either process in probing the polarized gluon structure
function of the proton. A subset of the radiative
corrections to production involving initial state quarks are also
performed and compared to leading order predictions.Comment: 21 pages + 5 postscript figures (included), OCIP/C-94-
âLower than a Snakeâs Bellyâ : Discursive Constructions of Dignity and Heroism in Low-Status Garbage Work
In this paper, we consider how dignity is discursively constructed in the context of work dominated by physicality and dirt. Based on semi-structured interviews with garbage workers, our analysis considers how the deprivations they experience are cast through discourses intended to construct their individual and collective worth. We consider the manner in which dignity maybe denied to such workers through popular repudiations of individuality and status. We demonstrate how this positioning arises from contact with physical dirt, and associations with socially dirty work based on ascriptions of servility, abuse and ambivalence. We go on to consider how garbage workers respond to this positioning through discourses of âeveryday heroismâ. Heroism is evoked through three interrelated narratives that speaks to a particular type of masculinity. The first takes the form of a classic process of reframing and recalibration through which workers not only renegotiate their public position and status, but also point to the inherent value to be had in working with dirt as part of that which we identify as a process of âaffirmationâ. The second narrative arises from the imposition of favourable social and occupational comparisons that effectively elevate garbage collectorsâ social position. The third discourseâand previously unobserved in respect of garbage workâcentres on paternalistic practices of care. Combined, these discourses disrupt the generally held view that dirty work is antithetical to heroism and wounds dignity