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Author |
Freitas, E.D.C.; Monteiro, C.M.B.; Ball, M.; Gomez-Cadenas, J.J.; Lopes, J.A.M.; Lux, T.; Sanchez, F.; dos Santos, J.M.F. |
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Title |
Secondary scintillation yield in high-pressure xenon gas for neutrinoless double beta decay (0 nu beta beta) search |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
684 |
Issue |
4-5 |
Pages |
205-210 |
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Keywords |
Neutrino; Neutrinoless double-beta decay; Secondary scintillation; Xenon; High-pressure |
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Abstract |
The search for neutrinoless double beta decay (0 nu beta beta) is an important topic in contemporary physics with many active experiments. New projects are planning to use high-pressure xenon gas as both source and detection medium. The secondary scintillation processes available in noble gases permit large amplification with negligible statistical fluctuations, offering the prospect of energy resolution approaching the Fano factor limit. This Letter reports results for xenon secondary scintillation yield, at room temperature, as a function of electric field in the gas scintillation gap for pressures ranging from 2 to 10 bar. A Large Area Avalanche Photodiode (LAAPD) collected the VUV secondary scintillation produced in the gas. X-rays directly absorbed in the LAAPD are used as a reference for determining the number of charge carriers produced by the scintillation pulse and, hence, the number of photons impinging the LAAPD. The number of photons produced per drifting electron and per kilovolt, the so-called scintillation amplification parameter, displays a small increase with pressure, ranging from 141 +/- 6 at 2 bar to 170 +/- 10 at 8 bar. In our setup, this Parameter does not increase above 8 bar due to nonnegligible electron attachment. The results are in good agreement with those presented in the literature in the 1 to 3 bar range. The increase of the scintillation amplification parameter with pressure for high gas densities has been also observed in former work at cryogenic temperatures. |
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Address |
[Freitas, E. D. C.; Monteiro, C. M. B.; Lopes, J. A. M.; dos Santos, J. M. F.] Univ Coimbra, GIAN CI, Dept Fis, P-3004516 Coimbra, Portugal, Email: jmf@gian.fis.uc.pt |
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Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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ISI:000275009600006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
487 |
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Author |
Gomez Dumm, D.; Roig, P.; Pich, A.; Portoles, J. |
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Title |
tau -> pi pi pi nu(tau) decays and the a(1)(1260) off-shell width revisited |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
685 |
Issue |
2-3 |
Pages |
158-164 |
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Keywords |
Hadron tau decays; Chiral Lagrangians; QCD; 1/N expansion |
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Abstract |
The tau -> pi pi pi nu(tau) decay is driven by the hadronization of the axial-vector current. Within the resonance chiral theory, and considering the large-N-C expansion, this process has been studied in Ref. [1] (D. Gomez Dumm, A. Pich, J. Portoles, 2004). In the light of later developments we revise here this previous work by including a new off-shell width for the lightest a(1) resonance that provides a good description of the tau -> pi pi pi nu(tau) spectrum and branching ratio. We also consider the role of the rho(1450) resonance in these observables. Thus we bring in an overall description of the tau -> pi pi pi nu(tau) process in excellent agreement with our present experimental knowledge. |
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Address |
[Pich, A.; Portoles, J.] Univ Valencia, CSIC, Dept Fis Teor, IFIC, E-46071 Valencia, Spain, Email: Jorge.Portoles@ific.uv.es |
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Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Notes |
ISI:000275148800010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
488 |
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Author |
Pierre Auger Collaboration (Abraham, J. et al); Pastor, S. |
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Title |
Measurement of the energy spectrum of cosmic rays above 10(18) eV using the Pierre Auger Observatory |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
685 |
Issue |
4-5 |
Pages |
239-246 |
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Keywords |
Pierre Auger Observatory; Cosmic rays; Energy spectrum |
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Abstract |
We report a measurement of the flux of cosmic rays with unprecedented precision and Statistics using the Pierre Auger Observatory Based on fluorescence observations in coincidence with at least one Surface detector we derive a spectrum for energies above 10(18) eV We also update the previously published energy spectrum obtained with the surface detector array The two spectra are combined addressing the systematic uncertainties and, in particular. the influence of the energy resolution on the spectral shape The spectrum can be described by a broken power law E-gamma with index gamma = 3 3 below the ankle which is measured at log(10)(E-ankle/eV) = 18 6 Above the ankle the spectrum is described by a power law with index 2 6 followed by a flux suppression, above about log(10)(E/eV) = 19 5, detected with high statistical significance. |
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Address |
[Ave, M.; Bluemer, H.; Daumiller, K.; Engel, R.; Garrido, X.; Haungs, A.; Heck, D.; Huege, T.; Keilhauer, B.; Klages, H. O.; Kleinfeller, J.; Mathes, H. J.; Mueller, S.; Oehlschlaeger, J.; Pierog, T.; Roth, M.; Salamida, F.; Schieler, H.; Schroeder, F.; Schuessler, F.; Smida, R.; Ulrich, R.; Unger, M.; Valino, I.] Karlsruhe Inst Technol, Inst Kernphys, Karlsruhe, Germany |
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Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Notes |
ISI:000275640600003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
480 |
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Author |
Botella, F.J.; Branco, G.C.; Rebelo, M.N. |
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Title |
Minimal flavour violation and multi-Higgs models |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
687 |
Issue |
2-3 |
Pages |
194-200 |
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Keywords |
Multi-Higgs models; Minimal Flavour Violation; FCNC; Flavour symmetries |
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Abstract |
We propose an extension of the hypothesis of Minimal Flavour Violation (MFV) to general multi-Higgs models without the assumption of Natural Flavour Conservation (NFC) in the Higgs sector. We study in detail under what conditions the neutral Higgs couplings are only functions of V-CKM and propose a MFV expansion for the neutral Higgs couplings to fermions. |
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Address |
[Branco, G. C.; Rebelo, M. N.] Inst Super Tecn, Dept Fis, P-1049001 Lisbon, Portugal, Email: fbotella@uv.es |
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Publisher |
Elsevier Science Bv |
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English |
Summary Language |
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ISSN |
0370-2693 |
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Notes |
ISI:000277070800019 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
457 |
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Author |
Mathieu, V.; Vento, V. |
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Title |
eta-eta ' mixing in the flavor basis and large N |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
688 |
Issue |
4-5 |
Pages |
314-318 |
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Keywords |
Meson; Mixing |
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Abstract |
The mass matrix for eta-eta' is derived in the flavor basis at O(p(4)) of the chiral Lagrangian using the large N approximation. Under certain assumptions, the mixing angle phi = 41.4 degrees and the decay constants ratio f(K)/f(pi) = 1.15 are calculated in agreement with the data. It appears that the FKS scheme arises as a special limit of the chiral Lagrangian. Their mass matrix is obtained without the hypothesis on the mixing pattern of the decay constants. |
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Address |
[Mathieu, Vincent] Univ Valencia, Dept Fis Teor, CSIC, E-46100 Valencia, Spain, Email: vincent.mathieu@umons.ac.be |
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Publisher |
Elsevier Science Bv |
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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 |
0370-2693 |
ISBN |
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Conference |
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Notes |
ISI:000278242600012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
428 |
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