28 research outputs found
Electroweak contributions to squark--gluino production at the LHC
We calculated the electroweak contributions to the hadronic production of a
squark in association with a gluino within the Minimal Supersymmetric Standard
Model (MSSM). Presented are complete next-to-leading order electroweak (NLO EW)
corrections at O(alpha_s^2 alpha), which include real photon and real quark
radiation processes. Also considered are photon induced tree level O(alpha_s
alpha) contributions.Comment: 23 pages, 15 figure
Electroweak Physics at LHC
The prospects for electroweak physics at the LHC are reviewed focusing mainly on precision studies. This includes projections for measurements of the effective Z pole weak mixing angle, of top quark, W boson, and Higgs scalar properties, and new physics searches
Charged particle jet measurements with the ALICE experiment in proton-proton collisions at the LHC
We present preliminary results of measurements of charged particle jet
properties in proton-proton collisions at = 7 TeV using the ALICE
detector. Jets are reconstructed using and SISCone jet
finding algorithms with resolution parameter in the range of transverse
momentum from 20 to 100 GeV/ in the midrapidity region
(\mid\eta\mid\textless 0.5). The uncorrected charged jet spectra obtained
using the three different jet finders show good agreement. The data are
compared to predictions from PYTHIA-Perugia0, PYTHIA-Perugia2011, and PHOJET.
The mean charged particle multiplicity in leading jets increases with
increasing jet and is consistent with model predictions. The radial
distributions of transverse momentum about the jet direction and the
distributions of the average radius containing 80% of the total jet
found in the jet cone ( in this analysis), indicate that high jets are more collimated than low jets.Comment: 6 pages, 6 figures, Conference Proceedings submitted for the 28th
Winter Workshop on Nuclear Dynamics, Puerto Rico, April 7-14, 201
Flavor Changing Effects in Family Nonuniversal Z' Models
Flavor-changing and CP-violating interactions of Z' to fermions are generally
present in models with extra U(1) gauge symmetry that are string-inspired or
related to broken gauged family symmetry. We study the consequences of such
couplings in fermion electric dipole moments, muon g-2, and K and B meson
mixings. From experimental limits or measured values, we constrain the
off-diagonal Z' couplings to fermions. Some of these constraints are comparable
or stronger than the existing constraints obtained from other observables.Comment: 17 pages, 2 figure
Hard Interactions of Quarks and Gluons: a Primer for LHC Physics
In this review article, we develop the perturbative framework for the
calculation of hard scattering processes. We undertake to provide both a
reasonably rigorous development of the formalism of hard scattering of quarks
and gluons as well as an intuitive understanding of the physics behind the
scattering. We emphasize the importance of logarithmic corrections as well as
power counting of the strong coupling constant in order to understand the
behavior of hard scattering processes. We include "rules of thumb" as well as
"official recommendations", and where possible seek to dispel some myths.
Experiences that have been gained at the Fermilab Tevatron are recounted and,
where appropriate, extrapolated to the LHC.Comment: 118 pages, 107 figures; to be published in Reports on Progress in
Physic
Sensitivity of LHC experiments to exotic highly ionising particles
The experiments at the Large Hadron Collider (LHC) are able to discover or
set limits on the production of exotic particles with TeV-scale masses
possessing values of electric and/or magnetic charge such that they behave as
highly ionising particles (HIPs). In this paper the sensitivity of the LHC
experiments to HIP production is discussed in detail. It is shown that a number
of different detection methods are required to investigate as fully as possible
the charge-mass range. These include direct detection as the HIPs pass through
either passive or active detectors and, in the case of magnetically charged
objects, the so-called induction method with which magnetic monopoles which
stop in accelerator and detector material could be observed. The benefit of
using complementary approaches to HIP detection is discussed.Comment: 20 pages, 52 figure
Hadronization in Z0 decay
The confinement transition from the quark and gluon degrees of freedom
appropriate in perturbation theory to the hadrons observed by real world
experiments is poorly understood. In this strongly interacting transition
regime we presently rely on models, which to varying degrees reflect possible
scenarios for the QCD dynamics. Because of the absence of beam and target
remnants, and the clean experimental conditions and high event rates, e+e-
annihilation to hadrons at the Z0 provides a unique laboratory, both
experimentally and theoretically, for the study of parton hadronization. This
review discusses current theoretical understanding of the hadronization of
partons, with particular emphasis on models of the non-perturbative phase, as
implemented in Monte Carlo simulation programs. Experimental results at LEP and
SLC are summarised and considered in the light of the models. Suggestions are
given for further measurements which could help to produce more progress in
understanding hadronization.Comment: Topical review, to appear in J.Phys.G, 80 page
The CDF Silicon Vertex Trigger
The Collider Detector at Fermilab (CDF) experiment's Silicon Vertex Trigger (SVT) is a system of 150 custom 9U VME boards that reconstructs axial tracks in the CDF silicon strip detector in a 15 μm pipeline. SVT's 35 μm impact parameter resolution enables CDF's Level 2 trigger to distinguish primary and secondary particles, and hence to collect large samples of hadronic bottom and charm decays. We review some of SVT's key design features. Speed is achieved with custom VLSI pattern recognition, linearized track fitting, pipelining, and parallel processing. Testing and reliability are aided by built-in logic state analysis and test-data sourcing at each board's input and output, a common interboard data link, and a universal “Merger” board for data fan-in/fan-out. Speed and adaptability are enhanced by use of modern FPGAs
