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Author |
Borexino Collaboration (Bellini, G. et al); Pena-Garay, C. |
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Title |
Absence of a day-night asymmetry in the Be-7 solar neutrino rate in Borexino |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
707 |
Issue |
1 |
Pages |
22-26 |
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Keywords |
Solar neutrinos; Day-night effect; CPT violation; Neutrino oscillations |
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Abstract |
We report the result of a search for a day-night asymmetry in the Be-7 solar neutrino interaction rate in the Borexino detector at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The measured asymmetry is A(dn) = 0.001 +/- 0.012 (stat) +/- 0.007 (syst), in agreement with the prediction of MSW-LMA solution for neutrino oscillations. This result disfavors MSW oscillations with mixing parameters in the LOW region at more than 8.5 sigma. This region is, for the first time, strongly disfavored without the use of reactor anti-neutrino data and therefore the assumption of CPT symmetry. The result can also be used to constrain some neutrino oscillation scenarios involving new physics. |
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Address |
[Carraro, C.; Davini, S.; Guardincerri, E.; Manuzio, G.; Pallavicini, M.; Perasso, S.; Salvo, C.; Testera, G.; Zavatarelli, S.] Univ Genoa, Dipartimento Fis, I-16146 Genoa, Italy, Email: marco.pallavicini@ge.infn.it |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
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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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Area |
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Expedition |
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Conference |
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Notes |
WOS:000299757000004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
901 |
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Permanent link to this record |
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Author |
Norena, J.; Verde, L.; Jimenez, R.; Pena-Garay, C.; Gomez, C. |
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Title |
Cancelling out systematic uncertainties |
Type |
Journal Article |
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Year |
2012 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
419 |
Issue |
2 |
Pages |
1040-1050 |
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Keywords |
methods: statistical; cosmology: theory |
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Abstract |
We present a method to minimize, or even cancel out, the nuisance parameters affecting a measurement. Our approach is general and can be applied to any experiment or observation where systematic errors are a concern e.g. are larger than statistical errors. We compare it with the Bayesian technique used to deal with nuisance parameters: marginalization, and show how the method compares and improves by avoiding biases. We illustrate the method with several examples taken from the astrophysics and cosmology world: baryonic acoustic oscillations (BAOs), cosmic clocks, Type Ia supernova (SNIa) luminosity distance, neutrino oscillations and dark matter detection. By applying the method we not only recover some known results but also find some interesting new ones. For BAO experiments we show how to combine radial and angular BAO measurements in order to completely eliminate the dependence on the sound horizon at radiation drag. In the case of exploiting SNIa as standard candles we show how the uncertainty in the luminosity distance by a second parameter modelled as a metallicity dependence can be eliminated or greatly reduced. When using cosmic clocks to measure the expansion rate of the universe, we demonstrate how a particular combination of observables nearly removes the metallicity dependence of the galaxy on determining differential ages, thus removing the agemetallicity degeneracy in stellar populations. We hope that these findings will be useful in future surveys to obtain robust constraints on the dark energy equation of state. |
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Address |
[Norena, Jorge; Verde, Licia; Jimenez, Raul] Univ Barcelona IEEC UB, ICREA, Barcelona 08028, Spain, Email: jorge.norena@icc.ub.edu |
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Publisher |
Wiley-Blackwell |
Place of Publication |
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Language |
English |
Summary Language |
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Edition |
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ISSN |
0035-8711 |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000298482300011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
890 |
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Permanent link to this record |
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Author |
Serenelli, A.M.; Haxton, W.C.; Pena-Garay, C. |
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Title |
Solar Models With Accretion. I. Application To The Solar Abundance Problem |
Type |
Journal Article |
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Year |
2011 |
Publication |
Astrophysical Journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
743 |
Issue |
1 |
Pages |
24 - 20pp |
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Keywords |
accretion, accretion disks; neutrinos; Sun: abundances; Sun: helioseismology; Sun: interior |
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Abstract |
We generate new standard solar models using newly analyzed nuclear fusion cross sections and present results for helioseismic quantities and solar neutrino fluxes. The status of the solar abundance problem is discussed. We investigate whether nonstandard solar models with accretion from the protoplanetary disk might alleviate this problem. We examine a broad range of models, analyzing metal-enriched and metal-depleted accretion and three scenarios for the timing of accretion. Only partial solutions are found. Formetal-rich accreted material (Z(ac) greater than or similar to 0.018) there exist combinations of accreted mass and metallicity that bring the depth of the convective zone into agreement with the helioseismic value. For the surface helium abundance, the helioseismic value is reproduced if metal-poor or metal-free accretion is assumed (Z(ac) less than or similar to 0.09). In both cases a few percent of the solar mass must be accreted. Precise values depend on when accretion takes place. We do not find a simultaneous solution to both problems but speculate that changing the hydrogen-to-helium mass ratio in the accreted material may lead to more satisfactory solutions. We also show that, with current data, solar neutrinos are already a very competitive source of information about the solar core and can help constraining possible accretion histories. Even without helioseismic constraints, solar neutrinos rule out the possibility that more than 0.02 M(circle dot) from the protoplanetary disk were accreted after the Sun settled on the main sequence. Finally, we discuss how measurements of neutrinos from the CN cycle could shed light on the interaction between the early Sun and its protoplanetary disk. |
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Address |
[Serenelli, Aldo M.] Fac Ciencias, CSIC IEEC, Inst Ciencias Espacio, Bellaterra 08193, Spain |
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Thesis |
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Publisher |
Iop Publishing Ltd |
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 |
0004-637x |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000297408300024 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
857 |
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Permanent link to this record |
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Author |
Borexino Collaboration (Bellini, G. et al); Pena-Garay, C. |
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Title |
Precision Measurement of the (7)Be Solar Neutrino Interaction Rate in Borexino |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
107 |
Issue |
14 |
Pages |
141302 - 5pp |
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Keywords |
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Abstract |
The rate of neutrino-electron elastic scattering interactions from 862 keV (7)Be solar neutrinos in Borexino is determined to be 46.0 +/- 1.5(stat)(-1.6)(+1.5)(syst)counts/(day . 100 ton). This corresponds to a nu(e)-equivalent (7)Be solar neutrino flux of (3.10 +/- 0.15) x 10(9) cm(-2) s(-1) and, under the assumption of nu(e) transition to other active neutrino flavours, yields an electron neutrino survival probability of 0.51 +/- 0.07 at 862 keV. The no flavor change hypothesis is ruled out at 5.0 sigma. A global solar neutrino analysis with free fluxes determines Phi(pp) = 6.06(-0.66)(+0.02) x 10(10) cm(-2) s(-1) and Phi(CNO) < 1.3 x 10(9) cm(-2) s(-1) (95% C.L.). These results significantly improve the precision with which the Mikheyev-Smirnov-Wolfenstein large mixing angle neutrino oscillation model is experimentally tested at low energy. |
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Address |
[Bellini, G; Bonetti, S; Avanzini, MB; Caccianiga, B; D'Angelo, D; Giammarchi, M; Ludhova, L; Meroni, E; Miramonti, L; Perasso, L; Ranucci, G; Re, A] Univ Studi & INFN, Dipartimento Fis, I-20133 Milan, Italy |
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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 |
0031-9007 |
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:000296285800007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
793 |
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Permanent link to this record |
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Author |
Jimenez, R.; Pena-Garay, C.; Verde, L. |
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Title |
Is it possible to explore Peccei-Quinn axions from frequency-dependence radiation dimming? |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
703 |
Issue |
3 |
Pages |
232-236 |
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Keywords |
Axion; CF; White dwarf |
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Abstract |
We explore how the Peccei-Quinn (PQ) axion parameter space can be constrained by the frequency-dependence dimming of radiation from astrophysical objects. To do so we perform accurate calculations of photon-axion conversion in the presence of a variable magnetic field. We propose several tests where the PQ axion parameter space can be explored with current and future astronomical surveys: the observed spectra of isolated neutron stars, occultations of background objects by white dwarfs and neutron stars, the light-curves of eclipsing binaries containing a white dwarf. We find that the lack of dimming of the light-curve of a detached eclipsing white dwarf binary recently observed, leads to relevant constraints on the photon-axion conversion. Current surveys designed for Earth-like planet searches are well matched to strengthen and improve the constraints on the PQ axion using astrophysical objects radiation dimming. |
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Address |
[Jimenez, R; Verde, L] Univ Barcelona IEEC UB, ICREA & ICC, Barcelona 08028, Spain, Email: jimenez@icc.ub.edu |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
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 |
0370-2693 |
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:000295198300005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
779 |
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Permanent link to this record |