10,244 research outputs found
Photoproduction of mesons in ultraperipheral heavy ion collisions at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC)
We investigate the photoproduction of mesons in ultraperipheral heavy
ion collisions at RHIC and LHC energies in the dipole approach and within two
phenomenological models based on the the Color Glass Condensate (CGC)
formalism. We estimate the integrated cross section and rapidity distribution
for meson production and compare our predictions with the data from the STAR
collaboration. In particular, we demonstrate that the total cross section at
RHIC is strongly dependent on the energy behavior of the dipole-target cross
section at low energies, which is not well determined in the dipole approach.
In contrast, the predictions at midrapidities at RHIC and in the full rapidity
at LHC are under theoretical control and can be used to test the QCD dynamics
at high energies.Comment: 6 pages, 5 figures, 1 table. Improved version to be published in
Physical Review
Vector Meson Production in Coherent Hadronic Interactions: An update on predictions for RHIC and LHC
In this letter we update our predictions for the photoproduction of vector
mesons in coherent and collisions at RHIC and LHC energies using the
color dipole approach and the Color Glass Condensate (CGC) formalism. In
particular, we present our predictions for the first run of the LHC at half
energy and for the rapidity dependence of the ratio between the and
cross sections at RHIC energies.Comment: 4 pages, 3 figure
FCNC in the minimal 3-3-1 model revisited
We show that in the minimal 3-3-1 model the flavor changing neutral currents
(FCNCs) do not impose necessarily strong constraints on the mass of the
of the model if we also consider the neutral scalar contributions to
such processes, like the neutral mesons mass difference and rare semileptonic
decays. We first obtain numerical values for all the mixing matrices of the
model i.e., the unitary matrices that rotate the left- and right-handed quarks
in each charge sector which give the correct mass of all the quarks and the CKM
mixing matrix. Then, we find that there is a range of parameters in which the
neutral scalar contributions to these processes may interfere with those of the
, implying this vector boson may be lighter than it has been thought.Comment: Extended version including the effect of a pseudoscalar. 37 pags. and
12 figures. New references added. Version matches the published versio
Surface-state electron dynamics in noble metals
Theoretical investigations of surface-state electron dynamics in noble metals
are reported. The dynamically screened interaction is computed, within
many-body theory, by going beyond a free-electron description of the metal
surface. Calculations of the inelastic linewidth of Shockley surface-state
electrons and holes in these materials are also presented. While the linewidth
of excited holes at the surface-state band edge () is
dominated by a two-dimensional decay channel, within the surface-state band
itself, our calculations indicate that major contributions to the
electron-electron interaction of surface-state electrons above the Fermi level
come from the underlying bulk electrons.Comment: 17 pages, 7 figures, to appear in Prog. Surf. Sc
Crystal engineering using functionalized adamantane
We performed a first principles investigation on the structural, electronic,
and optical properties of crystals made of chemically functionalized adamantane
molecules. Several molecular building blocks, formed by boron and nitrogen
substitutional functionalizations, were considered to build zincblende and
wurtzite crystals, and the resulting structures presented large bulk moduli and
cohesive energies, wide and direct bandgaps, and low dielectric constants
(low- materials). Those properties provide stability for such
structures up to room temperature, superior to those of typical molecular
crystals. This indicates a possible road map for crystal engineering using
functionalized diamondoids, with potential applications ranging from space
filling between conducting wires in nanodevices to nano-electro-mechanical
systems
The Higgs decay rate to two photons in a model with two fermiophobic-Higgs doublets
We consider a three Higgs doublet model with an symmetry in which
beside the SM-like doublet there are two fermiophobic doublets. Due to the new
charged scalars there is an enhancement in the two-photon decay while the other
channels have the same decay widths that the SM neutral Higgs. The fermiophobic
scalars are mass degenerated unless soft terms breaking the symmetry are
added.Comment: typos were corrected, the figures have been modified and the
conclusions were increased. Still contains 15 pages, 2 figure
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