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Author |
Doring, M.; Jido, D.; Oset, E. |
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Title |
Helicity amplitudes of the Lambda(1670) and two Lambda(1405) as dynamically generated resonances |
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 |
45 |
Issue |
3 |
Pages |
319-333 |
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Keywords |
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Abstract  |
We determine the helicity amplitudes A(1/2) and radiative decay widths in the transition Lambda(1670) -> gamma Y (Y = Lambda or Sigma(0)). The Lambda(1670) is treated as a dynamically generated resonance in meson-baryon chiral dynamics. We obtain the radiative decay widths of the Lambda(1670) to gamma Lambda as 2 +/- 1 keV and to -gamma Sigma(0) as 120 +/- 50 keV. Also, the Q(2)-dependence of the helicity amplitudes A(1/2) is calculated. We find that the K Xi component in the Lambda(1670) structure, mainly responsible for the dynamical generation of this resonance, is also responsible for the significant suppression of the decay ratio Gamma(gamma A)/Gamma(gamma Sigma 0). A measurement of the ratio would, thus, provide direct access to the nature of the Lambda(1670). To compare the result for the Lambda(1670), we calculate the helicity amplitudes Lambda(1/2) for the two states of the Lambda(1405). Also, the analytic continuation of Feynman parameterized integrals of more complicated loop amplitudes to the complex plane is developed which allows for an internally consistent evaluation of A(1/2). |
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Address |
[Doering, M.] Forschungszentrum Julich, Inst Kernphys, D-52425 Julich, Germany, Email: m.doering@fz-jueiich.de |
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Springer |
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English |
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ISSN |
1434-6001 |
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Notes |
ISI:000281972900006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
372 |
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Author |
Pierre Auger Collaboration (Abraham, J. et al); Pastor, S. |
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Title |
Measurement of the Depth of Maximum of Extensive Air Showers above 10(18) eV |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
104 |
Issue |
9 |
Pages |
091101 - 7pp |
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Keywords |
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Abstract |
We describe the measurement of the depth of maximum, X-max, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10(18) eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106 +/- 35-21) g/cm(2)/decade below 10(18.24) +/- (0.05) eV, and d24 +/- 3 g/cm(2)/ecade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm(2). The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed. |
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Address |
[Abraham, J.; De la Vega, G.; Garcia, B.; Videla, M.] Natl Technol Univ, Fac Mendoza, CONICET, CNEA, Mendoza, Argentina |
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Publisher |
Amer Physical Soc |
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English |
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Edition |
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ISSN |
0031-9007 |
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Notes |
ISI:000275252500006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
490 |
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Author |
Cirigliano, V.; Jenkins, J.P.; Gonzalez-Alonso, M. |
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Title |
Semileptonic decays of light quarks beyond the Standard Model |
Type |
Journal Article |
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Year |
2010 |
Publication |
Nuclear Physics B |
Abbreviated Journal |
Nucl. Phys. B |
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Volume |
830 |
Issue |
1-2 |
Pages |
95-115 |
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Keywords |
Semileptonic decays; CKM unitarity; Effective theory; Beyond the Standard Model |
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Abstract |
We describe non-standard contributions to semileptonic processes in a model independent way in terms of in SU(2)(L) x U(1)(Y) invariant effective lagrangian at the weak scale, front which we derive the low-energy effective lagrangian governing muon and beta decays. We find that the deviation from Cabibbo universality, Delta(CKM) equivalent to vertical bar V-ud vertical bar(2) + vertical bar V-us vertical bar(2) + vertical bar V-ub vertical bar(2) – 1, receives contributions from four effective operators. The phenomenological bound Delta(CKM) = (-1 +/- 6) x 10(-4) provides strong constraints on all four operators, corresponding to art effective scale Lambda > 11 TeV (90% CL). Depending on the operator, this constraint is at the same level or better then the Z pole observables. Conversely, precision electroweak constraints alone would allow universality violations as large as Delta(CKM) = -0.01 (90% CL). An observed Delta(CKM) not equal 0 at this level Could be explained in terms of a single four-fermion operator which is relatively poorly constrained by electroweak precision measurements. |
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Address |
[Cirigliano, Vincenzo; Jenkins, James P.; Gonzalez-Alonso, Martin] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA, Email: cirigliano@lanl.gov |
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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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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 |
0550-3213 |
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Conference |
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Notes |
ISI:000275150000003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
497 |
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Author |
Albertus, C.; Aoki, Y.; Boyle, P.A.; Christ, N.H.; Dumitrescu, T.T.; Flynn, J.M.; Ishikawa, T.; Izubuchi, T.; Loktik, O.; Sachrajda, C.T.; Soni, A.; Van de Water, R.S.; Wennekers, J.; Witzel, O. |
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Title |
Neutral B-meson mixing from unquenched lattice QCD with domain-wall light quarks and static b quarks |
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 |
1 |
Pages |
014505 - 29pp |
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Keywords |
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Abstract |
We demonstrate a method for calculating the neutral B-meson decay constants and mixing matrix elements in unquenched lattice QCD with domain-wall light quarks and static b-quarks. Our computation is performed on the "2 + 1'' flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice spacing of a approximate to 0.11 fm (a(-1) = 1.729 GeV) and a lattice spatial volume of approximately (1.8 fm)(3). We simulate at three different light sea quark masses with pion masses down to approximately 430 MeV, and extrapolate to the physical quark masses using a phenomenologically-motivated fit function based on next-to-leading order heavy-light meson SU(2) chiral perturbation theory. For the b-quarks, we use an improved formulation of the Eichten-Hill action with static link-smearing to increase the signal-to-noise ratio. We also improve the heavy-light axial current used to compute the B-meson decay constant to O(alpha(s)pa) using one-loop lattice perturbation theory. We present initial results for the SU(3)-breaking ratios f(Bs)/f(Bd) and xi = f(Bs)root B-Bs/f(Bd)root B-Bd, thereby demonstrating the viability of the method. For the ratio of decay constants, we find f(Bs)/f(Bd) = 1.15(12) and for the ratio of mixing matrix elements, we find xi = 1.13(12), where in both cases the errors reflect the combined statistical and systematic uncertainties, including an estimate of the size of neglected O(1/m(b)) effects. |
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Address |
[Albertus, C.; Flynn, J. M.; Sachrajda, C. T.] Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England |
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Corporate Author |
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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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Notes |
ISI:000280124300003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
405 |
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Author |
Yamagata-Sekihara, J.; Cabrera, D.; Vicente Vacas, M.J.; Hirenzaki, S. |
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Title |
Formation of phi Mesic Nuclei |
Type |
Journal Article |
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Year |
2010 |
Publication |
Progress of Theoretical Physics |
Abbreviated Journal |
Prog. Theor. Phys. |
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Volume |
124 |
Issue |
1 |
Pages |
147-162 |
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Keywords |
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Abstract |
We consider the structure and formation of the phi mesic nuclei to investigate the experimental feasibility of the observation of signals of the phi mesic nucleus formation. phi mesic nuclei are considered to be very important objects to study the in-medium modification of the phi-meson spectral function at finite density. We consider ((p) over bar, phi), (gamma, p) and (pi(-), n) reactions to produce a phi-meson inside the nucleus and evaluate the effects of its medium modifications to the reaction cross sections. We also estimate the consequences of the uncertainties of the in-medium (K) over bar self-energy to the phi-nucleus interaction. We find that it may be possible to see peak structures in the reaction spectra for the strong attractive potential cases. On the other hand, for strong absorptive interaction cases with relatively weak attraction, it is very difficult to observe clear peaks and we may need to know the spectrum shape in a wide energy region to deduce the properties of phi. |
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Address |
[Yamagata-Sekihara, Junko; Vacas, Manuel J. Vicente] Univ Valencia, CSIC, Dept Fis Teor, E-46071 Valencia, Spain |
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Corporate Author |
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Publisher |
Progress Theoretical Physics Publication Office |
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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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 |
0033-068x |
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:000280654900007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
396 |
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