767 research outputs found
Higgs boson production with one bottom quark jet at hadron colliders
We present total rates and kinematic distributions for the associated
production of a single bottom quark and a Higgs boson at the Tevatron and the
LHC. We include next-to-leading order QCD corrections and compare the results
obtained in the four and five flavor number schemes for parton distribution
functions.Comment: 4 pages, 8 figures, RevTeX
Probing Topcolor-Assisted Technicolor from Like-sign Top Pair Production at LHC
The topcolor-assisted technicolor (TC2) theory predicts tree-level
flavor-changing neutral-current (FCNC) top quark Yukawa couplings with
top-pions. Such FCNC interactions will induce like-sign top quark pair
productions at CERN Large Hadron Collider (LHC). While these rare productions
are far below the observable level in the Standard Model and other popular new
physics models such as the Minimal Supersymmetric Model, we find that in a
sound part of parameter space the TC2 model can enhance the production cross
sections to several tens of fb and thus may be observable at the LHC due to
rather low backgrounds. Searching for these productions at the LHC will serve
as an excellent probe for the TC2 model.Comment: 10 pages, 6 fig
Towards the Equation of State of Classical SU(2) Lattice Gauge Theory
We determine numerically the full complex Lyapunov spectrum of SU(2)
Yang-Mills fields on a 3-dimensional lattice from the classical chaotic
dynamics. The equation of state, S(E), is determined from the Kolmogorov-Sinai
entropy extrapolated to the large size limit.Comment: 12 pages, 8 PS figures, LaTe
Next-to-leading Log Resummation of Scalar and Pseudoscalar Higgs Boson Differential Cross-Sections at the LHC and Tevatron
The region of small transverse momentum in q qbar- and gg-initiated processes
must be studied in the framework of resummation to account for the large,
logarithmically-enhanced contributions to physical observables. In this paper,
we will calculate the fixed order next-to-leading order (NLO) perturbative
total and differential cross-sections for both a Standard Model (SM) scalar
Higgs boson and the Minimal Supersymmetric Standard Model's (MSSM) pseudoscalar
Higgs boson in the Heavy Quark Effective Theory (HQET) where the mass of the
top quark is taken to be infinite. Resummation coefficients B^2_g, C^2_gg for
the total cross-section resummation for the pseudoscalar case are given, as
well as C^1_gg for the differential cross-section.Comment: 18 pages, REVTeX4, 5 eps figures. v2: Typos corrected, references
added, a discussion of uncertainties was adde
Hip Anatomy and Ontogeny of Lower Limb Musculature in Three Species of Nonhuman Primates
The hip region is examined to determine what aspects of musculoskeletal anatomy are precociously developed in primate species with highly specialized modes of locomotion. Muscles of the hind limb were removed and weighed in each specimen, and the hip joint of selected specimens was studied in stained serial sections. No perinatal differences among species are evident, but in adults, the hip joint of Galago moholi (a leaping specialist) appears to have proportionally thick articular cartilage (relative to the subchondral plate) compared to two species of cheirogaleids. Muscle mass distribution in the hind limbs confirms previous observations that the quadriceps femoris muscle is especially large in Galago (in percent mass of the entire hind limb), while the hip region is smaller compared to the more quadrupedal cheirogaleids. Across age groups, the species with the least specialized locomotion as adults, Cheirogaleus medius, shows little or no change in proximal to distal percentage distribution of muscle mass. Galago has a larger percentage mass gain in the thigh. We suggest that muscle mass gain to specific limb segments may be a critical milestone for primates with extremely specialized modes of locomotion
Understanding single-top-quark production and jets at hadron colliders
I present an analysis of fully differential single-top-quark production plus
jets at next-to-leading order. I describe the effects of jet definitions,
top-quark mass, and higher orders on the shapes and normalizations of the
kinematic distributions, and quantify all theoretical uncertainties. I explain
how to interpret next-to-leading-order jet calculations, and compare them to
showering event generators. Using the program ZTOP, I show that HERWIG and
PYTHIA significantly underestimate both s-channel and t-channel
single-top-quark production, and propose a scheme to match the relevant samples
to the next-to-leading-order predictions.Comment: 40 pgs., revtex4, 35 ps figs; added Fig. 4, 1 Ref., minor
clarifications, to appear in Phys. Rev.
Combining Static and Dynamic Contract Checking for Curry
Static type systems are usually not sufficient to express all requirements on
function calls. Hence, contracts with pre- and postconditions can be used to
express more complex constraints on operations. Contracts can be checked at run
time to ensure that operations are only invoked with reasonable arguments and
return intended results. Although such dynamic contract checking provides more
reliable program execution, it requires execution time and could lead to
program crashes that might be detected with more advanced methods at compile
time. To improve this situation for declarative languages, we present an
approach to combine static and dynamic contract checking for the functional
logic language Curry. Based on a formal model of contract checking for
functional logic programming, we propose an automatic method to verify
contracts at compile time. If a contract is successfully verified, dynamic
checking of it can be omitted. This method decreases execution time without
degrading reliable program execution. In the best case, when all contracts are
statically verified, it provides trust in the software since crashes due to
contract violations cannot occur during program execution.Comment: Pre-proceedings paper presented at the 27th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur,
Belgium, 10-12 October 2017 (arXiv:1708.07854
Determination of polarized parton distribution functions and their uncertainties
We investigate the polarized parton distribution functions (PDFs) and their
uncertainties by using the world data on the spin asymmetry A_1. The
uncertainties of the polarized PDFs are estimated by the Hessian method. The up
and down valence-quark distributions are determined well. However, the
antiquark distributions have large uncertainties at this stage, and it is
particularly difficult to fix the gluon distribution. The \chi^2 analysis
produces a positively polarized gluon distribution, but even \Delta g(x)=0
could be allowed according to our uncertainty estimation. In comparison with
the previous AAC (Asymmetry Analysis Collaboration) parameterization in 2000,
accurate SLAC-E155 proton data are added to the analysis. We find that the E155
data improve the determination of the polarized PDFs, especially the polarized
antiquark distributions. In addition, the gluon-distribution uncertainties are
reduced due to the correlation with the antiquark distributions. We also show
the global analysis results with the condition \Delta g(x)=0 at the initial
scale, Q^2=1 GeV^2, for clarifying the error correlation effects with the gluon
distribution.Comment: 9 pages, 15 eps figures, REVTeX, FORTRAN package is available at the
web site http://www-hs.phys.saga-u.ac.jp/aac.html. Replaced 3 eps figures in
Fig.
Pion Excess, Nuclear Correlations, and the Interpretation of () Spin Transfer Experiments
Conventional theories of nuclear interactions predict a net increase in the
distribution of virtual pions in nuclei relative to free nucleons. Analysis of
data from several nuclear experiments has led to claims of evidence against
such a pion excess. These conclusions are usually based on a collective theory
(RPA) of the pions, which may be inadequate. The issue is the energy dependence
of the nuclear response, which differs for theories with strong NN correlations
from the RPA predictions. In the present paper, information about the energy
dependence is extracted from sum rules, which are calculated for such a
correlated, noncollective nuclear theory. The results lead to much reduced
sensitivity of nuclear reactions to the correlations that are responsible for
the pion excess. The primary example is spin transfer, for
which the expected effects are found to be smaller than the experimental
uncertainties. The analysis has consequences for Deep Inelastic Scattering
(DIS) experiments as well.Comment: 16 pages, LaTeX, no figures, submitted to Phys. Rev.
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