48,968 research outputs found
Massive c\bar c g - Calculation in Diffractive DIS and Diffractive D^* - Production at HERA
We calculate the cross section for -production in diffractive DIS
with finite quark masses at zero momentum transfer . The calculation is done
in the leading log(1/) approximation and is valid in the region of high
diffractive masses (small ). We apply our cross section formula
including both - and in a Monte Carlo simulation to
diffractive meson production at HERA. We compare our predictions to
results of H1 using three parameterizations for the unintegrated gluon density.Comment: 11 pages, 5 figure
Theory of inter-edge superexchange in zigzag edge magnetism
A graphene nanoribbon with zigzag edges has a gapped magnetic ground state
with an antiferromagnetic inter-edge superexchange interaction. We present a
theory based on asymptotic properties of the Dirac-model ribbon wavefunction
which predicts and ribbon-width dependencies for the
superexchange interaction strength and the charge gap respectively. We find
that, unlike the case of conventional atomic scale superexchange, opposite
spin-orientations on opposite edges of the ribbon are favored by both kinetic
and interaction energies.Comment: 4 pages 8 figure
Charmonia production from -hadron decays at LHC with -factorization: , and
We consider the production of and mesons originating from
the decays of -flavored hadrons at the LHC using the -factorization
approach. Our analysis covers both inclusive charmonia production and
production of mesons in association with bosons. We apply the
transverse momentum dependent (or unintegrated) gluon density in a proton
derived from Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation and
adopt fragmentation functions based on the non-relativistic QCD factorization
to describe the inclusive -hadron decays into the different charmonium
states. Our predictions agree well with latest experimental data taken by the
CMS, ATLAS and LHCb Collaborations at , and ~TeV. The
contributions from double parton scattering to the associated non-prompt
production are estimated and found to be small.Comment: 12 pages, 5 figure
Z boson production in proton-lead collisions at the LHC accounting for transverse momenta of initial partons
We perform a calculation of inclusive boson production in proton-lead
collisions at the LHC taking into account the transverse momenta of the initial
partons. We use the framework of -factorization combining transverse
momentum dependent parton distributions (TMDs) with off-shell matrix elements.
In order to do it we need to construct appropriate TMDs for lead nuclei which
is done using the parton branching method. Our computations are compared with
data from CMS taken at TeV. The results are in good agreement
with the measurements especially the transverse momentum distribution of the
boson.Comment: 17 pages, 12 figure
Testing the parton evolution with the use of two-body final states
We consider the production of quarks and Drell-Yan lepton pairs at
LHC conditions focusing attention on the total transverse momentum of the
produced pair and on the azimuthal angle between the momenta of the outgoing
particles. Plotting the corresponding distributions in bins of the final state
invariant mass, one can reconstruct the full map of the transverse momentum
dependent parton densities in a proton. We give examples of how can these
distributions can look like at the LHC energies.Comment: 8 pages, 7 figure
Comparison of techniques to reconstruct VHE gamma-ray showers from multiple stereoscopic Cherenkov images
For air showers observed simultaneously by more than two imaging atmospheric
Cherenkov telescopes, the shower geometry is overconstrained by the images and
image information should be combined taking into account the quality of the
images. Different algorithms are discussed and tested experimentally using data
obtained from observations of Mkn 501 with the HEGRA IACT system. Most of these
algorithms provide an estimate of the accuracy of the reconstruction of shower
geometry on an event-by-event basis, allowing, e.g., to select higher-quality
subsamples for precision measurements.Comment: 14 Pages, 6 figures, Late
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