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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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Publisher |
Springer |
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Language |
English |
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Abbreviated Series Title  |
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ISSN |
1126-6708 |
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Notes |
ISI:000281504500002 |
Approved |
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 |
CDF Collaboration (Aaltonen, T. et al); Cabrera, S. |
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Title |
Measurement of the Ratio sigma(t(t)over-bar)/sigma(Z/gamma*-> ll) and Precise Extraction of the t(t)over-bar Cross Section |
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 |
1 |
Pages |
012001 - 7pp |
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Keywords |
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Abstract |
We report a measurement of the ratio of the t (t) over bar to Z/gamma* production cross sections in root s = 1.96 TeV p (p) over bar collisions using data corresponding to an integrated luminosity of up to 4.6 fb(-1), collected by the CDF II detector. The t (t) over bar cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/gamma* -> ll cross section predicted by the standard model, the extracted t (t) over bar cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result sigma(t (t) over bar) = 7.70 +/- 0.52 pb, for a top-quark mass of 172.5 GeV/c(2). |
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Address |
[Blair, R. E.; Byrum, K. L.; LeCompte, T.; Nodulman, L.; Paramanov, A. A.; Wagner, R. G.; Wicklund, A. B.] Argonne Natl Lab, Argonne, IL 60439 USA |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Language |
English |
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ISSN |
0031-9007 |
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Notes |
ISI:000279273300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
282 |
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Author |
Bordes, J.; Chan, H.M.; Tsun, T.S. |
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Title |
A solution to the strong CP problem transforming the theta angle to the KM CP-violating phase |
Type |
Journal Article |
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Year |
2010 |
Publication |
International Journal of Modern Physics A |
Abbreviated Journal |
Int. J. Mod. Phys. A |
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Volume |
25 |
Issue |
32 |
Pages |
5897-5911 |
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Keywords |
Strong CP phase; CKM matrix; CP violation |
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Abstract |
It is shown that in the scheme with a rotating fermion mass matrix (i.e. one with a scale-dependent orientation in generation space) suggested earlier for explaining fermion mixing and mass hierarchy, the theta angle term in the QCD action of topological origin can be eliminated by chiral transformations, while giving still nonzero masses to all quarks. Instead, the effects of such transformations get transmitted by the rotation to the CKM matrix as the KM phase giving, for theta of order unity, a Jarlskog invariant typically of order 10(-5), as experimentally observed. Strong and weak CP violations appear then as just two facets of the same phenomenon. |
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Address |
[Bordes, Jose] Univ Valencia, Ctr Mixto CSIC, Dept Fis Teor, E-46100 Burjassot, Valencia, Spain, Email: jose.m.bordes@uv.es |
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Publisher |
World Scientific Publ Co Pte Ltd |
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Language |
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 |
0217-751x |
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:000288429300006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
536 |
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Author |
BABAR Collaboration (del Amo Sanchez, P. et al); Lopez-March, N.; Martinez-Vidal, F.; Oyanguren, A. |
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Title |
Measurement of the B-0 -> pi(-)l(+)nu and B+ -> eta(l)l(+)nu branching fractions, the B-0 -> pi(-)l(+)nu and B+ -> eta l(+)nu form- factor shapes, and determination of |Vub| |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
83 |
Issue |
5 |
Pages |
052011 - 16pp |
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Keywords |
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Abstract |
We report the results of a study of the exclusive charmless semileptonic decays, B+ -> eta(l)l(+)nu and B-0 -> pi(-)l(+)nu undertaken with approximately 464 x 10(6) B (B) over bar pairs collected at the Y(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions for B+ -> eta l(+)nu and B-0 -> pi(-)l(+)nu decays in three and 12 bins of q(2), respectively, from which we extract the f (+)(q(2)) form-factor shapes and the total branching fractions B(B+ -> eta l(+)nu)= (0.36 +/- 0.05(stat) +/- 0.04(syst)) x 10(-4) and B(B-0 -> pi(-)l(+)nu) = (1.42 +/- 0.05(stat) +/- 0.07(syst)) x 10(-4). We also measure B(B+ -> eta'l(+)nu) = (0.24 +/- 0.08(stat) +/- 0.03(syst)) x 10(-4). We obtain values for the magnitude of the CKM matrix element |V-ub| using three different QCD calculations. |
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Address |
[Sanchez, P. del Amo; Lees, J. P.; Poireau, V.; Prencipe, E.; Tisserand, V.] Univ Savoie, Lab Annecy Le Vieux Phys Particules, CNRS, IN2P3, F-74941 Annecy Le Vieux, France |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
1550-7998 |
ISBN |
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Area |
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Conference |
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Notes |
ISI:000288787100002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
537 |
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Author |
Martin Camalich, J.; Geng, L.S.; Vicente Vacas, M.J. |
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Title |
Lowest-lying baryon masses in covariant SU(3)-flavor chiral perturbation theory |
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 |
7 |
Pages |
074504 - 7pp |
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Keywords |
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Abstract |
We present an analysis of the baryon-octet and -decuplet masses using covariant SU(3)-flavor chiral perturbation theory up to next-to-leading order. Besides the description of the physical masses we address the problem of the lattice QCD extrapolation. Using the PACS-CS Collaboration data we show that a good description of the lattice points can be achieved at next-to-leading order with the covariant loop amplitudes and phenomenologically determined values for the meson-baryon couplings. Moreover, the extrapolation to the physical point up to this order is found to be better than the linear one given at leading-order by the Gell-Mann-Okubo approach. The importance that a reliable combination of lattice QCD and chiral perturbation theory may have for hadron phenomenology is emphasized with the prediction of the pion-baryon and strange-baryon sigma terms. |
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Address |
[Martin Camalich, J.; Geng, L. S.; Vicente Vacas, M. J.] Univ Valencia, CSIC, Dept Fis Teor, E-46071 Valencia, Spain |
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Corporate Author |
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Thesis |
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Publisher |
Amer Physical Soc |
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 |
1550-7998 |
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:000283121000002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
352 |
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