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Author |
AGATA Collaboration (Crespi, F.C.L. et al); Gadea, A. |
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Title  |
Isospin Character of Low-Lying Pygmy Dipole States in Pb-208 via Inelastic Scattering of O-17 Ions |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
113 |
Issue |
1 |
Pages |
012501 - 5pp |
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Keywords |
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Abstract |
The properties of pygmy dipole states in Pb-208 were investigated using the Pb-208(O-17, O-17'gamma) reaction at 340 MeV and measuring the gamma decay with high resolution with the AGATA demonstrator array. Cross sections and angular distributions of the emitted gamma rays and of the scattered particles were measured. The results are compared with (gamma, gamma') and (p, p') data. The data analysis with the distorted wave Born approximation approach gives a good description of the elastic scattering and of the inelastic excitation of the 2(+) and 3(-) states. For the dipole transitions a form factor obtained by folding a microscopically calculated transition density was used for the first time. This has allowed us to extract the isoscalar component of the 1(-) excited states from 4 to 8 MeV. |
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Address |
[Crespi, F. C. L.; Bracco, A.; Nicolini, R.; Pellegri, L.; Leoni, S.; Avigo, R.; Bottoni, S.; Camera, F.; Ceruti, S.; Morales, A. I.; Vandone, V.; Pullia, A.] Univ Milan, Dipartimento Fis, I-20133 Milan, Italy, Email: angela.bracco@mi.infn.it |
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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 |
WOS:000338665200009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1848 |
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Author |
Wendt, A. et al; Algora, A. |
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Title |
Isospin symmetry in the sd shell: Transition strengths in the neutron-deficient sd shell nucleus Ar-33 |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
90 |
Issue |
5 |
Pages |
054301 - 7pp |
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Keywords |
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Abstract |
Reduced transition strengths of the deexciting transitions from the first two excited states in Ar-33 were measured in a relativistic Coulomb excitation experiment at the GSI Helmholtz center. The radioactive ion beam was produced by fragmentation of a primary Ar-36 beam on a Be-9 target followed by the selection of the reaction product of interest via the GSI Fragment Separator. The (33A)r beam hit a secondary Au-197 target with an energy of approximately 145 MeV/nucleon. An array of high-purity germanium cluster detectors and large-volume BaF2 scintillator detectors were employed for gamma-ray spectroscopy at the secondary target position. The Lund-York-Cologne Calorimeter was used to track the outgoing ions and to identify the nuclear reaction channels. For the two lowest energy excited states of Ar-33 the reduced transition strengths have been determined. With these first results the T-z = -3/2 nucleus Ar-33 is now, together with Na-21 (T-z = -1/2), the only neutron-deficient odd-A sd shell nucleus in which experimental transition strengths are available. The experimental values are compared to results of shell-model calculations which describe simultaneously mirror-energy differences and transition-strength values of mirror pairs in the sd shell in a consistent way. |
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Address |
[Wendt, A.; Taprogge, J.; Reiter, P.; Blazhev, A.; Braun, N.; Geibel, K.; Hackstein, M.; Moschner, K.; Siebeck, B.; Warr, N.] Univ Cologne, Inst Kernphys, Cologne, Germany |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
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ISSN |
0556-2813 |
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Conference |
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Notes |
WOS:000344489100002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2005 |
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Author |
Ledwig, T.; Nieves, J.; Pich, A.; Ruiz Arriola, E.; Ruiz de Elvira, J. |
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Title |
Large-N-c naturalness in coupled-channel meson-meson scattering |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
90 |
Issue |
11 |
Pages |
114020 - 17pp |
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Keywords |
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Abstract |
The analysis of hadronic interactions with effective field theory techniques is complicated by the appearance of a large number of low-energy constants, which are usually fitted to data. On the other hand, the large-N-c limit helps to impose natural short-distance constraints on these low-energy constants, providing a parameter reduction. A Bayesian interpretation of the expected 1/N-c accuracy allows for an easy and efficient implementation of these constraints, using an augmented chi(2). We apply this approach to the analysis of meson-meson scattering, in conjunction with chiral perturbation theory to one loop and coupled-channel unitarity, and show that it helps to largely reduce the many existing ambiguities and simultaneously provide an acceptable description of the available phase shifts. |
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Address |
[Ledwig, T.; Nieves, J.; Pich, A.] Univ Valencia, CSIC, IFIC, Dept Fis Teor, Valencia 46071, Spain |
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Publisher |
Amer Physical Soc |
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 |
1550-7998 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000348730800008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2100 |
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Author |
Aristizabal Sierra, D.; Tortola, M.; Valle, J.W.F.; Vicente, A. |
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Title |
Leptogenesis with a dynamical seesaw scale |
Type |
Journal Article |
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Year |
2014 |
Publication |
Journal of Cosmology and Astroparticle Physics |
Abbreviated Journal |
J. Cosmol. Astropart. Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
052 - 20pp |
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Keywords |
leptogenesis; baryon asymmetry; particle physics – cosmology connection; neutrino theory |
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Abstract |
In the simplest type-I seesaw leptogenesis scenario right-handed neutrino annihilation processes are absent. However, in the presence of new interactions these processes are possible and can affect the resulting B – L asymmetry in an important way. A prominent example is provided by models with spontaneous lepton number violation, where the existence of new dynamical degrees of freedom can play a crucial role. In this context, we provide a model-independent discussion of the effects of right-handed neutrino annihilations. We show that in the weak washout regime, as long as the scattering processes remain slow compared with the Hubble expansion rate throughout the relevant temperature range, the efficiency can be largely enhanced, reaching in some cases maximal values. Moreover, the B – L asymmetry yield turns out to be independent upon initial conditions, in contrast to the “standard” case. On the other hand, when the annihilation processes are fast, the right-handed neutrino distribution tends to a thermal one down to low temperatures, implying a drastic suppression of the efficiency which in some cases can render the B – L generation mechanism inoperative. |
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Address |
[Sierra, D. Aristizabal; Vicente, A.] Univ Liege, IFPA, Dept Astrophys Geophys & Oceanog, B-4000 Liege, Belgium, Email: daristizabal@ulg.ac.be; |
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Publisher |
Iop Publishing Ltd |
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 |
1475-7516 |
ISBN |
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Conference |
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Notes |
WOS:000339802700053 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1868 |
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Author |
Park, J.H. |
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Title |
Lepton flavor violation from right-handed neutrino thresholds |
Type |
Journal Article |
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Year |
2014 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
89 |
Issue |
9 |
Pages |
095005 - 6pp |
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Keywords |
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Abstract |
Charged lepton flavor violation is reappraised in the context of a supersymmetric seesaw mechanism. It is pointed out that a nontrivial flavor structure of right-handed neutrinos, whose effect has been thus far less studied, can give rise to significant slepton flavor transitions. Under the premise that the neutrino Yukawa couplings are of O(1), the right-handed neutrino mixing contribution could form a basis of the μ-> e gamma amplitude, which by itself might lead to an experimentally accessible rate, given a typical low-energy sparticle spectrum. Emphasis is placed on the crucial role of the recently measured lepton mixing angle theta(13) as well as the leptonic CP-violating phases. |
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Address |
[Park, Jae-hyeon] Tech Univ Dresden, Inst Kern & Teilchenphys, D-01069 Dresden, Germany |
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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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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000335532400004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1788 |
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