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Author |
Kaskulov, M.; Hernandez, E.; Oset, E. |
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Title |
On the background in the gamma p -> omega(pi(0)gamma)p reaction and mixed event simulation |
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 |
46 |
Issue |
2 |
Pages |
223-230 |
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Abstract |
In this paper we evaluate sources of background of the gamma p -> omega p reaction, with the omega detected through its pi(0)gamma decay channel, to compare with the experiment carried out at ELSA. We find background from gamma p -> pi(0)pi(0)p followed by decay of a pi(0) into two gamma, recombining one pi(0) and one gamma, and from the gamma p -> pi(0)eta p reaction with subsequent decay of the eta into two photons. This background accounts for the data at pi(0)gamma invariant masses beyond 700 MeV, but strength is missing at lower invariant masses which was attributed to photon misidentification events, which we simulate to get a good reproduction of the experimental background. Once this is done, we perform an event mixing simulation to reproduce the calculated background and we find that the method provides a good description of the background. A closer look reveals this is accidental. We show that the mixed event generated background in the region of the omega mass and beyond is completely tied to the events at low pi(0)gamma invariant masses where the d sigma/dM(pi 0 gamma) distribution is much larger. This has as a consequence that the mixed event method produces the same background at high invariant masses independently of the actual background in that region, as a consequence of which, the method is unsuited to give the background at energies around the peak of the omega and beyond. |
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Address |
[Kaskulov, M.] Univ Giessen, Inst Theoret Phys, D-35392 Giessen, Germany, Email: murat.kaskulov@theo.physik.uni-giessen.de |
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Springer |
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English |
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ISSN |
1434-6001 |
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Notes |
ISI:000284869600008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
313 |
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Author |
Hernandez, E.; Nieves, J.; Valverde, M. |
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Title |
Coherent pion production off nuclei at T2K and MiniBooNE energies revisited |
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 |
077303 - 4pp |
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Keywords |
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Abstract |
As a result of a new improved fit to old bubble chamber data of the dominant axial C-5(A) nucleon-to-delta form factor, and due to the relevance of this form factor for neutrino induced coherent pion production, we reevaluate our model predictions in [Phys. Rev. D 79, 013002 ( 2009)] for different observables of the latter reaction. Central values for the total cross sections increase by 20%-30%, while differential cross sections do not change their shape appreciably. Furthermore, we also compute the uncertainties on total, differential, and flux-averaged cross sections induced by the errors in the determination of C-5(A). Our new results turn out to be compatible within about 1 sigma with the former ones. Finally, we stress the existing tension between the recent experimental determination of the sigma(CCcoh pi(+))/sigma(NCcoh pi(0)) ratio by the SciBooNE Collaboration and the theoretical predictions. |
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Address |
[Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Notes |
ISI:000282945200003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
361 |
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Author |
Albertus, C.; Hernandez, E.; Nieves, J. |
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Title |
Hyperfine mixing in electromagnetic decay of doubly heavy bc baryons |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
690 |
Issue |
3 |
Pages |
265-271 |
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Keywords |
Hyperfine mixing; Double heavy bc baryons |
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Abstract |
We investigate the role of hyperfine mixing in the electromagnetic decay of ground state doubly heavy bc baryons. As in the case of a previous calculation on b -> c semileptonic decays of doubly heavy baryons, we find large corrections to the electromagnetic decay widths due to this mixing. Contrary to the weak case just mentioned, we find here that one cannot use electromagnetic width relations obtained in the infinite heavy quark mass limit to experimentally extract information on the admixtures in a model independent way. |
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Address |
[Albertus, C.; Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: gajatee@usal.es |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Conference |
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Notes |
ISI:000279388800012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
416 |
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Permanent link to this record |
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Author |
Hernandez, E.; Nieves, J.; Valverde, M.; Vicente Vacas, M.J. |
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Title |
N-Delta(1232) axial form factors from weak pion production |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
81 |
Issue |
8 |
Pages |
085046 - 5pp |
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Keywords |
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Abstract |
The N Delta axial form factors are determined from neutrino induced pion production ANL and BNL data by using a theoretical model that accounts both for background mechanisms and deuteron effects. We find violations of the off-diagonal Goldberger-Treiman relation at the level of 2 sigma which might have an impact in background calculations for T2K and MiniBooNE low energy neutrino oscillation precision experiments. |
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Address |
[Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Conference |
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Notes |
ISI:000277205000163 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
462 |
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Permanent link to this record |
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Author |
Albertus, C.; Hernandez, E.; Nieves, J. |
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Title |
Hyperfine mixing in b -> c semileptonic decay of doubly heavy baryons |
Type |
Journal Article |
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Year |
2010 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
683 |
Issue |
1 |
Pages |
21-25 |
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Keywords |
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Abstract |
We qualitatively corroborate the results of [W. Roberts, M. Pervin, Int. J. Mod. Phys. A 24 (2009) 2401] according to which hyperfine mixing greatly affects the decay widths of b -> c semileptonic decays involving doubly heavy bc baryons. However, our predictions for the decay widths of the unmixed states differ from those reported in the work of Roberts and Pervin by a factor of 2, and this discrepancy translates to the mixed case. We further show that the predictions of heavy quark spin symmetry, might be used in the future to experimentally extract information on the admixtures in the actual physical bc baryons, in a model independent manner. |
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Address |
[Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: gajatee@usal.es |
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Publisher |
Elsevier Science Bv |
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Language |
English |
Summary Language |
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Series Editor |
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ISSN |
0370-2693 |
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Conference |
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Notes |
ISI:000274129600005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
501 |
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Permanent link to this record |
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Author |
Hernandez, E.; Nieves, J. |
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Title |
Study of the strong Sigma(b) -> Lambda(b)pi and Sigma*(b) -> Lambda(b)pi in a nonrelativistic quark model |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
84 |
Issue |
5 |
Pages |
057902 - 5pp |
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Keywords |
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Abstract |
We present results for the strong widths corresponding to the Sigma(b) -> Lambda(b)pi and Sigma*(b) -> Lambda(b)pi decays. We apply our model from Phys. Rev. D 72, 094022 (2005), where we previously studied the corresponding transitions in the charmed sector. Our nonrelativistic constituent quark model uses wave functions that take advantage of the constraints imposed by heavy quark symmetry. The partial conservation of axial current hypothesis allows us to determine the strong vertices from an analysis of the axial current matrix elements. |
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Address |
[Hernandez, E] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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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:000295327700002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
776 |
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Permanent link to this record |
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Author |
Albertus, C.; Hernandez, E.; Nieves, J. |
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Title |
Exclusive c -> s, d semileptonic decays of ground-state spin-1/2 doubly charmed baryons |
Type |
Journal Article |
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Year |
2011 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
704 |
Issue |
5 |
Pages |
499-509 |
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Keywords |
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Abstract |
We evaluate exclusive semileptonic decays of ground-state spin-1/2 doubly heavy charmed baryons driven by a c -> s, d transition at the quark level. Our results for the form factors are consistent with heavy quark spin symmetry constraints which are valid in the limit of an infinitely massive charm quark and near zero recoil. Only a few exclusive semileptonic decay channels have been theoretically analyzed before. For those cases we find that our results are in a reasonable agreement with previous calculations. |
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Address |
[Albertus, C.; Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain, Email: gajatee@usal.es |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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English |
Summary Language |
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Series Editor |
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ISSN |
0370-2693 |
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Conference |
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Notes |
WOS:000296549200017 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ elepoucu @ |
Serial |
828 |
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Permanent link to this record |
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Author |
Flynn, J.M.; Hernandez, E.; Nieves, J. |
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Title |
Triply heavy baryons and heavy quark spin symmetry |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
85 |
Issue |
1 |
Pages |
014012 - 10pp |
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Keywords |
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Abstract |
We study the semileptonic b -> c decays of the lowest-lying triply heavy baryons made from b and c quarks in the limit m(b), m(c) >> Lambda(QCD) and close to the zero-recoil point. The separate heavy-quark spin symmetries strongly constrain the matrix elements, leading to single form factors for ccb -> ccc, bbc -> ccb, and bbb -> bbc baryon decays. We also study the effects on these systems of using a Y-shaped confinement potential, as suggested by lattice QCD results for the interaction between three static quarks. |
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Address |
[Flynn, J. M.] Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Expedition |
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Conference |
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Notes |
WOS:000298989300007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
874 |
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Permanent link to this record |
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Author |
Albertus, C.; Hernandez, E.; Nieves, J. |
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Title |
Exclusive c -> s, d semileptonic decays of ground-state spin-1/2 and spin-3/2 doubly heavy cb baryons |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
85 |
Issue |
9 |
Pages |
094035 - 21pp |
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Keywords |
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Abstract |
We evaluate exclusive semileptonic decays of ground-state spin-1/2 and spin-3/2 doubly heavy cb baryons driven by a c --> s, d transition at the quark level. We check our results for the form factors against heavy quark spin symmetry constraints obtained in the limit of very large heavy quark masses and near zero recoil. Based on those constraints we make model-independent, though approximate, predictions for ratios of decay widths. |
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Address |
[Albertus, C.; Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, Spain |
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Publisher |
Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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Expedition |
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Conference |
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Notes |
WOS:000304652600002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
1043 |
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Permanent link to this record |
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Author |
Hernandez, E.; Nieves, J.; Vicente Vacas, M.J. |
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Title |
Single pion production in neutrino-nucleus scattering |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
87 |
Issue |
11 |
Pages |
113009 - 11pp |
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Keywords |
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Abstract |
We study 1 pi production in both charged and neutral current neutrino-nucleus scattering for neutrino energies below 2 GeV. We use a theoretical model for one pion production at the nucleon level that we correct for medium effects. The results are incorporated into a cascade program that apart from production also includes the pion final state interaction inside the nucleus. Besides, in some specific channels coherent pi production is also possible and we evaluate its contribution as well. Our results for total and differential cross sections are compared with recent data from the MiniBooNE Collaboration. The model provides an overall acceptable description of the data, better for neutral-current than for charged-current channels, although the theory is systematically below the data. Differential cross sections, folded with the full neutrino flux, show that most of the missing pions lie in the forward direction and at high energies. |
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Address |
[Hernandez, E.] Univ Salamanca, Dept Fis Fundamental, E-37008 Salamanca, 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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Language |
English |
Summary Language |
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ISSN |
1550-7998 |
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Conference |
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Notes |
WOS:000320769600004 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
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Call Number |
IFIC @ pastor @ |
Serial |
1485 |
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Permanent link to this record |