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Author |
Greynat, D.; de Rafael, E.; Vulvert, G. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Asymptotic behaviour of pion-pion total cross-sections |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
03 |
Issue |
3 |
Pages |
107 - 21pp |
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Keywords |
QCD Phenomenology; Phenomenological Models |
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Abstract |
We derive a sum rule which shows that the Froissart-Martin bound for the asymptotic behaviour of the pi pi total cross sections at high energies, if modulated by the Lukaszuk-Martin coefficient of the leading log(2)s behaviour, cannot be an optimal bound in QCD. We next compute the total cross sections for pi(+)pi(-), pi(+/-)pi(0) and pi(0)pi(0) scattering within the framework of the constituent chiral quark model (C chi QM) in the limit of a large number of colours N-c and discuss their asymptotic behaviours. The same pi pi cross sections are also discussed within the general framework of Large-N-c QCD and we show that it is possible to make an Ansatz for the isospin I = 1 and I = 0 spectrum which satisfy the Froissart-Martin bound with coefficients which, contrary to the Lukaszuk-Martin coefficient, are not singular in the chiral limit and have the correct Large-N-c counting. We finally propose a simple phenomenological model which matches the low energy behaviours of the sigma(total)(pi +/-pi 0)(s) cross section predicted by the CxQM with the high energy behaviour predicted by the Large-N-c Ansatz. The magnitude of these cross sections at very high energies is of the order of those observed for the pp and pp scattering total cross sections. |
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Address |
[Greynat, David] Univ Naples Federico II, Dipartimento Sci Fis, I-80126 Naples, Italy, Email: david.greynat@gmail.com; |
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Springer |
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English |
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ISSN |
1029-8479 |
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Notes |
WOS:000333803000003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration ![sorted by International Collaboration field, ascending order (up)](img/sort_asc.gif) |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1747 |
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Author |
LHCb Collaboration (Aaij, R. et al); Martinez-Vidal, F.; Oyanguren, A.; Ruiz Valls, P. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Evidence for the decay B-c(+) -> J/psi 3 pi(+)2 pi(-) |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
05 |
Issue |
5 |
Pages |
148 - 17pp |
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Keywords |
Hadron-Hadron Scattering; QCD; Branching fraction; B physics; Flavor physics |
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Abstract |
Evidence is presented for the decay B-c(+) -> J/psi 3 pi(+)2 pi(-) using proton-proton collision data, corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb detector. A signal yield of 32 +/- 8 decays is found with a significance of 4.5 standard deviations. The ratio of the branching fraction of the B-c(+) -> J/psi 3 pi(+)2 pi(-) decay to that of the B-c(+) -> J/psi pi(+) decay is measured to be B(B-c(+) -> J/psi 3 pi(+)2 pi(-))/B(B-c(+) -> J/psi pi(+)) = 1.74 +/- 0.44 +/- 0.24, where the first uncertainty is statistical and the second is systematic. |
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Address |
[Bediaga, I.; De Miranda, J. M.; Rodrigues, F. Ferreira; Gomes, A.; Hicheur, A.; Massafferri, A.; dos Reis, A. C.; Rodrigues, A. B.] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil, Email: Ivan.Belyaev@cern.ch; |
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Springer |
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English |
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1029-8479 |
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Conference |
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Notes |
WOS:000336978600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration ![sorted by International Collaboration field, ascending order (up)](img/sort_asc.gif) |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1818 |
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Permanent link to this record |
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Author |
Baker, M.J.; Bordes, J.; Dominguez, C.A.; Peñarrocha, J.; Schilcher, K. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
B meson decay constants f(Bc), f(Bs) and f(B) from QCD sum rules |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
032 - 16pp |
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Keywords |
Sum Rules; QCD |
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Abstract |
Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant f(Bc), and revisit f(B) and f(Bs). Results exhibit excellent stability in a wide range of values of the integration radius in the complex squared energy plane, and of the order of the Legendre polynomial. Results are f(Bc) = 528 +/- 19 MeV, f(B) = 186 +/- 14 MeV, and f(Bs) = 222 +/- 12 MeV. |
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Address |
[Baker, M. J.; Bordes, J.; Penarrocha, J.] Univ Valencia, Ctr Mixto CSIC, Dept Fis Teor, E-46100 Burjassot, Valencia, Spain, Email: baker.michael.james@googlemail.com; |
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Springer |
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English |
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ISSN |
1029-8479 |
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Conference |
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Notes |
WOS:000339422800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration ![sorted by International Collaboration field, ascending order (up)](img/sort_asc.gif) |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1846 |
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Permanent link to this record |
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Author |
Bernardoni, F.; Blossier, B.; Bulava, J.; Della Morte, M.; Fritzsch, P.; Garron, N.; Gerardin, A.; Heitger, J.; von Hippel, G.; Simma, H.; Sommer, R. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Decay constants of B-mesons from non-perturbative HQET with two light dynamical quarks |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
735 |
Issue |
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Pages |
349-356 |
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Keywords |
Lattice QCD; Heavy Quark Effective Theory; Bottom quarks; Meson decay |
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Abstract |
We present a computation of B-meson decay constants from lattice QCD simulations within the framework of Heavy Quark Effective Theory for the b-quark. The next-to-leading order corrections in the HQET expansion are included non-perturbatively. Based on N-f = 2 gauge field ensembles, covering three lattice spacings a approximate to (0.08-0.05) fm and pion masses down to 190 MeV, a variational method for extracting hadronic matrix elements is used to keep systematic errors under control. In addition we perform a careful autocorrelation analysis in the extrapolation to the continuum and to the physical pion mass limits. Our final results read f(B) = 186(13) MeV, f(Bs) = 224(14) MeV and f(Bs)/f(B) = 1.203(65). A comparison with other results in the literature does not reveal a dependence on the number of dynamical quarks, and effects from truncating HQET appear to be negligible. |
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Address |
[Bernardoni, Fabio; Simma, Hubert; Sommer, Rainer] NIC DESY, D-15738 Zeuthen, Germany |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Edition |
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ISSN |
0370-2693 |
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Notes |
WOS:000340048900061 |
Approved |
no |
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Is ISI |
yes |
International Collaboration ![sorted by International Collaboration field, ascending order (up)](img/sort_asc.gif) |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1881 |
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Permanent link to this record |
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Author |
Binosi, D.; Ibañez, D.; Papavassiliou, J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Nonperturbative study of the four gluon vertex |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
09 |
Issue |
9 |
Pages |
059 - 32pp |
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Keywords |
Nonperturbative Effects; QCD; Confinement |
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Abstract |
In this paper we study the nonperturbative structure of the SU(3) four-gluon vertex in the Landau gauge, concentrating on contributions quadratic in the metric. We employ an approximation scheme where “one-loop” diagrams are computed using fully dressed gluon and ghost propagators, and tree-level vertices. When a suitable kinematical configuration depending on a single momentum scale p is chosen, only two structures emerge: the tree-level four-gluon vertex, and a tensor orthogonal to it. A detailed numerical analysis reveals that the form factor associated with this latter tensor displays a change of sign (zero-crossing) in the deep infrared, and finally diverges logarithmically. The origin of this characteristic behavior is proven to be entirely due to the masslessness of the ghost propagators forming the corresponding ghost-loop diagram, in close analogy to a similar effect established for the three-gluon vertex. However, in the case at hand, and under the approximations employed, this particular divergence does not affect the form factor proportional to the tree-level tensor, which remains finite in the entire range of momenta, and deviates moderately from its naive tree-level value. It turns out that the kinematic configuration chosen is ideal for carrying out lattice simulations, because it eliminates from the connected Green's function all one-particle reducible contributions, projecting out the genuine one-particle irreducible vertex. Motivated by this possibility, we discuss in detail how a hypothetical lattice measurement of this quantity would compare to the results presented here, and the potential interference from an additional tensorial structure, allowed by Bose symmetry, but not encountered within our scheme. |
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Address |
[Binosi, D.; Ibanez, D.] European Ctr Theoret Studies Nucl Phys & Related, I-38123 Villazzano, TN, Italy, Email: binosi@ectstar.eu; |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series 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 |
1029-8479 |
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 |
WOS:000342215400001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration ![sorted by International Collaboration field, ascending order (up)](img/sort_asc.gif) |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1954 |
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Permanent link to this record |