217 research outputs found
Near-threshold Z-pair production in the semi-phenomenological model of unstable particles
Near-threshold production of neutral boson pairs is considered within the
framework of the model of unstable particles with smeared mass. The results of
calculations are in good agreement with LEP II data and Monte-Carlo
simulations.Comment: 7 pages, 2 figure
Nonperturbative and spin effects in the central exclusive production of tensor meson
We discuss central exclusive production (CEP) of the tensor
meson in proton-(anti)proton collisions at Tevatron, RHIC and LHC energies. The
amplitude for the process is derived within the -factorisation approach.
Differential and total cross sections are calculated for several unintegrated
gluon distributions (UGDFs). We compare exclusive production of all charmonium
states and . Equally good description
of the recent Tevatron data is achieved both with Martin-Ryskin
phenomenological UGDF and UGDF based on unified BFKL-DGLAP approach. Unlike for
Higgs production, the main contribution to the diffractive amplitude of heavy
quarkonia comes from nonperturbative region of gluon transverse momenta
Q_{\perp}<1\,\GeV. At 0, depending on UGDF we predict the
contribution of to the channel to be
comparable or larger than that of the one. This is partially due
to a significant contribution from lower polarization states for
and for meson. Corresponding
theoretical uncertainties are discussed.Comment: 18 pages, 12 figures, discrepancies with Durham group results
clarified, numerics corrected, basic conclusions unchanged, acknowledgements
adde
On Semidefinite Programming Relaxations of the Travelling Salesman Problem (Replaced by DP 2008-96)
AMS classification: 90C22, 20Cxx, 70-08traveling salesman problem;semidefinite programming;quadratic as- signment problem
Evidence of Odderon-exchange from scaling properties of elastic scattering at TeV energies
We study the scaling properties of the differential cross section of elastic
proton-proton () and proton-antiproton () collisions at high
energies. We introduce a new scaling function, that scales -- within the
experimental errors -- all the ISR data on elastic scattering from
to GeV to the same universal curve. We explore the
scaling properties of the differential cross-sections of the elastic and
collisions in a limited TeV energy range. Rescaling the TOTEM
data from TeV to and TeV, and comparing it to D0
data at TeV, our results provide an evidence for a -channel
Odderon exchange at TeV energies, with a significance of at least 6.26.
We complete this work with a model-dependent evaluation of the domain of
validity of the new scaling and its violations. We find that the scaling
is valid, model dependently, within GeV TeV,
with a range gradually narrowing with decreasing colliding energies.Comment: Accepted in EPJ C, with typos fixed, reorganized institutions
updated, Appendix A, B, C, D, E added, 60 pages, 29 figures, 13 tables,
Odderon significance: 6.26 sigma, conclusions unchange
On the Lovasz O-number of Almost Regular Graphs With Application to Erdos-Renyi Graphs
AMS classifications: 05C69; 90C35; 90C22;Erdos-Renyi graph;stability number;Lovasz O-number;Schrijver O-number;C*-algebra;semidefinite programming
Exploiting Group Symmetry in Truss Topology Optimization
AMS classification: 90C22, 20Cxx, 70-08truss topology optimization;semidefinite programming;group symmetry
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