62 research outputs found
Confirmation of a cluster of galaxies hidden behind the Galactic bulge using the VVV Survey
Suzaku and Chandra X-ray observations detected a new cluster of galaxies,
Suzaku J1759-3450, at a redshift z=0.13. It is located behind the Milky Way,
and the high Galactic dust extinction renders it nearly invisible at optical
wavelengths. We attempt here to confirm the galaxy cluster with near-infrared
imaging observations, and to characterize its central member galaxies. Images
from the VVV survey were used to detect candidate member galaxies of Suzaku
J1759-3450 within the central region of the cluster, up to 350 kpc from the
X-ray peak emission. Color-magnitude and color-color diagrams and morphology
criteria allowed us to select the galaxies among the numerous foreground
sources. Fifteen candidate cluster members were found very close to a modeled
red-sequence at the redshift of the cluster. Five members are extremely bright,
and one is possibly a cD galaxy. The asymmetry in the spatial distribution of
the galaxies respect to the X-ray peak emission is an indicator of that this
cluster is still suffering a virialization process. Our investigation of Suzaku
J1759-3450 demonstrates the potential of the VVV Survey to study the hidden
population of galaxies in the Zone of Avoidance.Comment: 7 pages, 5 figures. Accepted for Publication in Astronomy &
Astrophysic
Confirmation of a galaxy cluster hidden behind the Galactic bulge using the VVV survey
Context. S uzaku and Chandra X-ray observations detected a new cluster of galaxies, Suzaku J1759â3450, at a redshift z = 0.13. It is located behind the Milky Way, and the high Galactic dust extinction renders it nearly invisible at optical wavelengths. Aims. We attempt here to confirm the galaxy cluster with near-infrared imaging observations and to characterize its central member galaxies. Methods. Images from the VVV survey were used to detect candidate member galaxies of Suzaku J1759â3450 within the central region of the cluster up to 350 kpc from the X-ray peak emission. Colorâmagnitude diagrams, colorâcolor diagrams, and morphology criteria allowed us to select the galaxies among the numerous foreground sources. Results. Fifteen candidate cluster members were found very close to a modeled red-sequence at the redshift of the cluster. Five members are extremely bright, and one is possibly a cD galaxy. The asymmetry in the spatial distribution of the galaxies with respect to the X-ray peak emission is an indicator that this cluster is still suffering a virialization process. Conclusions. Our investigation of Suzaku J1759â3450 demonstrates the potential of the VVV survey to study the hidden population of galaxies in the zone of avoidance.Fil: Coldwell Lloveras, Georgina Vanesa. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, FĂsicas y Naturales. Departamento de GeofĂsica y AstronomĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan; ArgentinaFil: Alonso Giraldes, Maria Sol. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, FĂsicas y Naturales. Departamento de GeofĂsica y AstronomĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan; ArgentinaFil: Duplancic Videla, Maria Fernanda. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, FĂsicas y Naturales. Departamento de GeofĂsica y AstronomĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan; ArgentinaFil: Hempel, Maren. Pontificia Universidad CatĂłlica de Chile; ChileFil: Ivanov, Valentin D.. Observatorio Europeo del Sur; ChileFil: Minniti, Dante. Observatorio Europeo del Sur; Chile. Specola Vaticana Osservatorio Astronomico Vaticano; Italia. Universidad AndrĂ©s Bello; Chil
Moments of inertia, nucleon axial-vector coupling, the {\bf 8}, {\bf 10}, and mass spectrums and the higher SU(3)_f representation mass splittings in the Skyrme model
The broad importance of a recent experimental discovery of pentaquarks
requires more theoretical insight into the structure of higher representation
multiplets. The nucleon axial-vector coupling, moments of inertia, the {\bf 8},
{\bf 10}, , and absolute mass spectra and the
higher SU(3) representation mass splittings for the multiplets ,
, , , , , and are computed in the framework of the minimal extended
Skyrme model by using only one free parameter, i.e., the Skyrme charge . The
analysis presented in this paper represents simple and clear theoretical
estimates, obtained without using any experimental results for higher
(,...) multiplets. The obtained results are in good agreement
with other chiral soliton model approaches that more extensively use
experimental results as inputs.Comment: 22 pages, 12 figures, 9 tables, version accepted in JHE
Double Parton Scattering Singularity in One-Loop Integrals
We present a detailed study of the double parton scattering (DPS)
singularity, which is a specific type of Landau singularity that can occur in
certain one-loop graphs in theories with massless particles. A simple formula
for the DPS singular part of a four-point diagram with arbitrary
internal/external particles is derived in terms of the transverse momentum
integral of a product of light cone wavefunctions with tree-level matrix
elements. This is used to reproduce and explain some results for DPS
singularities in box integrals that have been obtained using traditional loop
integration techniques. The formula can be straightforwardly generalised to
calculate the DPS singularity in loops with an arbitrary number of external
particles. We use the generalised version to explain why the specific MHV and
NMHV six-photon amplitudes often studied by the NLO multileg community are not
divergent at the DPS singular point, and point out that whilst all NMHV
amplitudes are always finite, certain MHV amplitudes do contain a DPS
divergence. It is shown that our framework for calculating DPS divergences in
loop diagrams is entirely consistent with the `two-parton GPD' framework of
Diehl and Schafer for calculating proton-proton DPS cross sections, but is
inconsistent with the `double PDF' framework of Snigirev.Comment: 29 pages, 8 figures. Minor corrections and clarifications added.
Version accepted for publication in JHE
Rare decay in the Skyrme model
Rare nonleptonic decay branching ratio
is estimated by means of the QCD enhanced effective weak Hamiltonian
supplemented by the SU(3) Skyrme model used to estimate the nonperturbative
matrix elements. The whole scheme is equivalent to that which works well for
the nonleptonic hyperon and decays. The computed rate is in a good
agreement with data.Comment: 4 pages, version to appear in Phys. Rev.
Rare B Decays with a HyperCP Particle of Spin One
In light of recent experimental information from the CLEO, BaBar, KTeV, and
Belle collaborations, we investigate some consequences of the possibility that
a light spin-one particle is responsible for the three Sigma^+ -> p mu^+ mu^-
events observed by the HyperCP experiment. In particular, allowing the new
particle to have both vector and axial-vector couplings to ordinary fermions,
we systematically study its contributions to various processes involving
b-flavored mesons, including B-Bbar mixing as well as leptonic, inclusive, and
exclusive B decays. Using the latest experimental data, we extract bounds on
its couplings and subsequently estimate upper limits for the branching ratios
of a number of B decays with the new particle. This can serve to guide
experimental searches for the particle in order to help confirm or refute its
existence.Comment: 17 pages, 3 figures; discussion on spin-0 case modified, few errors
corrected, main conclusions unchange
On Glauber modes in Soft-Collinear Effective Theory
Gluon interactions involving spectator partons in collisions at hadronic
machines are investigated. We find a class of examples in which a mode, called
Glauber gluons, must be introduced to the effective theory for consistency.Comment: 19 pages, three figures. Uses JHEP3.cl
Hard exclusive processes and higher-order QCD corrections
The short review of the higher order corrections to the hard exclusive
processes is given. Different approaches are discussed and the importance of
higher-order calculations is stressed.Comment: 17 pages; talk given at the 9th Adriatic Meeting, Dubrovnik 200
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