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Author |
Borja, E.F.; Diaz-Polo, J.; Garay, I.; Livine, E.R. |
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Title |
Dynamics for a 2-vertex quantum gravity model |
Type |
Journal Article |
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Year |
2010 |
Publication |
Classical and Quantum Gravity |
Abbreviated Journal |
Class. Quantum Gravity |
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Volume |
27 |
Issue |
23 |
Pages |
235010 - 34pp |
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Keywords |
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Abstract  |
We use the recently introduced U(N) framework for loop quantum gravity to study the dynamics of spin network states on the simplest class of graphs: two vertices linked with an arbitrary number N of edges. Such graphs represent two regions, in and out, separated by a boundary surface. We study the algebraic structure of the Hilbert space of spin networks from the U(N) perspective. In particular, we describe the algebra of operators acting on that space and discuss their relation to the standard holonomy operator of loop quantum gravity. Furthermore, we show that it is possible to make the restriction to the isotropic/homogeneous sector of the model by imposing the invariance under a global U(N) symmetry. We then propose a U(N)-invariant Hamiltonian operator and study the induced dynamics. Finally, we explore the analogies between this model and loop quantum cosmology and sketch some possible generalizations of it. |
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Address |
[Borja, Enrique F.; Garay, Inaki] Univ Erlangen Nurnberg, Inst Theoret Phys 3, D-91058 Erlangen, Germany, Email: etera.livine@ens-lyon.fr |
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Iop Publishing Ltd |
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English |
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ISSN |
0264-9381 |
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Notes |
ISI:000284211600011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
341 |
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Author |
Aguilar, A.C.; Binosi, D.; Papavassiliou, J. |
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Title |
QCD effective charges from lattice data |
Type |
Journal Article |
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Year |
2010 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
002 - 24pp |
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Keywords |
Nonperturbative Effects; QCD |
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Abstract |
We use recent lattice data on the gluon and ghost propagators, as well as the Kugo-Ojima function, in order to extract the non-perturbative behavior of two particular definitions of the QCD effective charge, one based on the pinch technique construction, and one obtained from the standard ghost-gluon vertex. The construction relies crucially on the definition of two dimensionful quantities, which are invariant under the renormalization group, and are built out of very particular combinations of the aforementioned Green's functions. The main non-perturbative feature of both effective charges, encoded in the infrared finiteness of the gluon propagator and ghost dressing function used in their definition, is the freezing at a common finite (non-vanishing) value, in agreement with a plethora of theoretical and phenomenological expectations. We discuss the sizable discrepancy between the freezing values obtained from the present lattice analysis and the corresponding estimates derived from several phenomenological studies, and attribute its origin to the difference in the gauges employed. A particular toy calculation suggests that the modifications induced to the non-perturbative gluon propagator by the gauge choice may indeed account for the observed deviation of the freezing values. |
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Address |
[Aguilar, A. C.] Fed Univ ABC, CCNH, BR-09210170 Santo Andre, Brazil, Email: arlene.aguilar@ufabc.edu.br |
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Springer |
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English |
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ISSN |
1126-6708 |
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Notes |
ISI:000281504500002 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
384 |
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Author |
Martinez Torres, A.; Oset, E. |
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Title |
Novel Interpretation of the “Theta(+)(1540) Pentaquark” Peak |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
105 |
Issue |
9 |
Pages |
092001 - 4pp |
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Keywords |
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Abstract |
We use a theoretical model of the gamma d --> K+K- np reaction adapted to the experiment done at LEPS where a peak was observed and associated with the Theta(+)(1540) pentaquark. The study shows that the method used in the experiment to assign momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K(+)n invariant mass in the region of the claimed Theta(+)(1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2 sigma significance. |
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Address |
[Martinez Torres, A.] Univ Valencia, Ctr Mixto, CSIC, Inst Invest Paterna,Dept Fis Teor, Valencia 46071, Spain |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
0031-9007 |
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Conference |
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Notes |
ISI:000281272700005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
387 |
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Author |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S. |
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Title |
Studying the underlying event in Drell-Yan and high transverse momentum jet production at the Tevatron |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
82 |
Issue |
3 |
Pages |
034001 - 21pp |
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Keywords |
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Abstract |
We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles produced in association with a large transverse momentum jet (similar to 2: 2 fb(-1)) or with a Drell-Yan lepton pair (similar to 2.7 fb(-1)) in the Z-boson mass region [70 < M(pair) < 110 GeV/c(2)] as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton pair or the leading jet in each event to define regions of eta-phi space that are sensitive to the modeling of the underlying event. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte Carlo models. |
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Address |
[Chen, Y. C.; Hou, S.; Martin, V.; Mitra, A.; Teng, P. K.; Tsai, S. -Y.; Wang, S. M.] Acad Sinica, Inst Phys, Taipei 11529, Taiwan |
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Amer Physical Soc |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000280486500001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
277 |
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Author |
BABAR Collaboration (Lees, J.P. et al); Azzolini, V.; Lopez-March, N.; Martinez-Vidal, F.; Milanes, D.A.; Oyanguren, A. |
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Title |
Measurement of the gamma gamma* -> eta c transition form factor |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
81 |
Issue |
5 |
Pages |
052010 - 18pp |
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Keywords |
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Abstract |
We study the reaction e(+)e(-) -> e(+)e(-) eta(c), eta(c) -> KSK +/-pi(-/+) and obtain eta(c) mass and width values 2982.2 +/- 0.4 +/- 1.6 MeV/c(2) and 31.7 +/- 1.2 +/- 0.8 MeV, respectively. We find Gamma(eta(c) -> gamma gamma)B(eta(c) -> KK pi) = 0.374 +/- 0.009 +/- 0.031 keV, and measure the gamma gamma* -> eta(c) transition form factor in the momentum transfer range from 2 to 50 GeV2. The analysis is based on 469 fb(-1) of integrated luminosity collected at PEP-II with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. |
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Address |
[Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.] Univ Savoie, CNRS, IN2P3, LAPP, F-74941 Annecy Le Vieux, France |
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Publisher |
Amer Physical Soc |
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English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1550-7998 |
ISBN |
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Expedition |
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Conference |
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Notes |
ISI:000276194200018 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
473 |
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Author |
Sun, B.X.; Garzon, E.J.; Oset, E. |
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Title |
Radiative decay into gamma-baryon of dynamically generated resonances from the vector-baryon interaction |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
82 |
Issue |
3 |
Pages |
034028 - 11pp |
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Keywords |
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Abstract |
We study the radiative decay into gamma and a baryon of the SU(3) octet and decuplet of nine and ten resonances that are dynamically generated from the interaction of vector mesons with baryons of the octet and the decuplet, respectively. We obtain quite different partial decay widths for the various resonances, and for different charge states of the same resonance, suggesting that the experimental investigation of these radiative decays should bring much information on the nature of these resonances. For the case of baryons of the octet we determine the helicity amplitudes and compare them with experimental data when available. |
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Address |
[Sun, Bao-Xi] Beijing Univ Technol, Coll Appl Sci, Inst Theoret Phys, Beijing 100124, Peoples R China |
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Publisher |
Amer Physical Soc |
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English |
Summary Language |
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Series Volume |
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ISSN |
1550-7998 |
ISBN |
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Expedition |
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Conference |
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Notes |
ISI:000281070700003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
392 |
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Author |
Tolos, L.; Molina, R.; Oset, E.; Ramos, A. |
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Title |
(K)over-bar* mesons in dense matter |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
82 |
Issue |
4 |
Pages |
045210 - 12pp |
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Keywords |
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Abstract |
We study the properties of (K) over bar* mesons in nuclear matter using a unitary approach in coupled channels within the framework of the local hidden gauge formalism and incorporating the (K) over bar pi decay channel in matter. The in-medium (K) over bar *N interaction accounts for Pauli blocking effects and incorporates the (K) over bar* self-energy in a self-consistent manner. We also obtain the (K) over bar* (off-shell) spectral function and analyze its behavior at finite density and momentum. At a normal nuclear matter density, the (K) over bar* meson feels a moderately attractive potential, while the (K) over bar* width becomes five times larger than in free space. We estimate the transparency ratio of the gamma A -> K+K*(-) A` reaction, which we propose as a feasible scenario at the present facilities to detect changes in the properties of the (K) over bar* meson in nuclear medium. |
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Address |
[Tolos, L.] Univ Groningen, Theory Grp KVI, NL-9747 AA Groningen, Netherlands, Email: tolos@kvi.nl |
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Publisher |
Amer Physical Soc |
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English |
Summary Language |
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Edition |
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ISSN |
0556-2813 |
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Notes |
ISI:000283648400011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
335 |
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Author |
Esteves, J.N.; Romao, J.C.; Hirsch, M.; Vicente, A.; Porod, W.; Staub, F. |
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Title |
LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM |
Type |
Journal Article |
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Year |
2010 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
077 - 44pp |
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Keywords |
Supersymmetry Phenomenology |
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Abstract |
We study the phenomenology of a supersymmetric left-right model, assuming minimal supergravity boundary conditions. Both left-right and (B-L) symmetries are broken at an energy scale close to, but significantly below the GUT scale. Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for superpotential and soft parameters complete at 2-loop order. At low energies lepton flavour violation (LFV) and small, but potentially measurable mass splittings in the charged scalar lepton sector appear, due to the RGE running. Different from the supersymmetric “pure seesaw” models, both, LFV and slepton mass splittings, occur not only in the left-but also in the right slepton sector. Especially, ratios of LFV slepton decays, such as Br((tau) over bar (R) -> μchi(0)(1))/Br((tau) over bar (L) -> μchi(0)(1)) are sensitive to the ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts a polarization asymmetry of the outgoing positrons in the decay mu(+) -> e(+)gamma, A similar to [0, 1], which differs from the pure seesaw “prediction” A = 1. Observation of any of these signals allows to distinguish this model from any of the three standard, pure (mSugra) seesaw setups. |
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Address |
[Esteves, J. N.; Romao, J. C.] Inst Super Tecn, Dept Fis, P-1049001 Lisbon, Portugal, Email: joaomest@cftp.ist.utl.pt |
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Publisher |
Springer |
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English |
Summary Language |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1126-6708 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000285964200015 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
532 |
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Author |
Oset, E.; Ramos, A. |
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Title |
Dynamically generated resonances from the vector octet-baryon octet interaction |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
44 |
Issue |
3 |
Pages |
445-454 |
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Keywords |
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Abstract |
We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled-channels unitary approach. We examine the scattering amplitudes and their poles, which can be associated to known J(P) = 1/2(-), 3/2(-) baryon resonances, in some cases, or give predictions in other ones. The formalism employed produces doublets of degenerate J(P) = 1/2(-), 3/2(-) states, a pattern which is observed experimentally in several cases. The findings of this work should also be useful to guide present experimental programs searching for new resonances, in particular in the strange sector where the current information is very poor. |
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Address |
[Oset, E.] Univ Valencia, Ctr Mixto, CSIC, Inst Invest Paterna,Dept Fis Teor, Valencia 46071, Spain, Email: ramos@ecm.ub.es |
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Publisher |
Springer |
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English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Edition |
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ISSN |
1434-6001 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000278159300011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
447 |
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Author |
Sarkar, S.; Sun, B.X.; Oset, E.; Vicente Vacas, M.J. |
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Title |
Dynamically generated resonances from the vector octet-baryon decuplet interaction |
Type |
Journal Article |
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Year |
2010 |
Publication |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
44 |
Issue |
3 |
Pages |
431-443 |
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Keywords |
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Abstract |
We study the interaction of the octet of vector mesons with the decuplet of baryons using Lagrangians of the hidden gauge theory for vector interactions. The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances, while there are predictions for new ones at the energy frontier of the experimental research. The work offers guidelines on how to search for these resonances. |
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Address |
[Sarkar, Sourav; Sun, Bao-Xi; Oset, E.; Vicente Vacas, M. J.] Univ Valencia, Ctr Mixto, CSIC, Inst Invest Paterna,Dept Fis Teor, Valencia 46071, Spain, Email: sourav@veccal.ernet.in |
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Publisher |
Springer |
Place of Publication |
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Language |
English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6001 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
ISI:000278159300010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
446 |
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| Permanent link to this record |
