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n_TOF Collaboration (Barbagallo, M. et al); Domingo-Pardo, C.; Tain, J.L.; Tarifeño-Saldivia, A. |
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Title |
Be-7(n,alpha)He-4 Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
117 |
Issue |
15 |
Pages |
152701 - 7pp |
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Abstract  |
The energy-dependent cross section of the (7)Bed(n,alpha)He-4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be-7 and by the low reaction cross section have been overcome at nTOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the nTOF facility at CERN, the availability of a sufficient amount of chemically pure Be-7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be-7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved. |
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Address |
[Barbagallo, M.; Colonna, N.; Damone, L.; Mastromarco, M.; Mazzone, A.; Tagliente, G.; Variale, V.] Ist Nazl Fis Nucl, Sez Bari, Bari, Italy, Email: nicola.colonna@ba.infn.it |
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Amer Physical Soc |
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0031-9007 |
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Notes |
WOS:000384479300003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2822 |
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Author |
ATLAS Collaboration (Aad, G. et al); Alvarez Piqueras, D.; Aparisi Pozo, J.A.; Bailey, A.J.; Barranco Navarro, L.; Cabrera Urban, S.; Castillo, F.L.; Castillo Gimenez, V.; Cerda Alberich, L.; Costa, M.J.; Escobar, C.; Estrada Pastor, O.; Ferrer, A.; Fiorini, L.; Fullana Torregrosa, E.; Fuster, J.; Garcia, C.; Garcia Navarro, J.E.; Gonzalez de la Hoz, S.; Higon-Rodriguez, E.; Jimenez Pena, J.; Lacasta, C.; Lozano Bahilo, J.J.; Madaffari, D.; Mamuzic, J.; Marti-Garcia, S.; Melini, D.; Miñano, M.; Mitsou, V.A.; Rodriguez Bosca, S.; Rodriguez Rodriguez, D.; Ruiz-Martinez, A.; Salt, J.; Santra, A.; Soldevila, U.; Sanchez, J.; Valero, A.; Valls Ferrer, J.A.; Vos, M. |
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Title |
Measurement of Azimuthal Anisotropy of Muons from Charm and Bottom Hadrons in pp Collisions at root s=13 TeV with the ATLAS Detector |
Type |
Journal Article |
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Year |
2020 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
124 |
Issue |
8 |
Pages |
082301 - 20pp |
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Abstract |
The elliptic flow of muons from the decay of charm and bottom hadrons is measured in pp collisions at root s = 13 TeV using a data sample with an integrated luminosity of 150 pb(-1) recorded by the ATLAS detector at the LHC. The muons from heavy-flavor decay are separated from light-hadron decay muons using momentum imbalance between the tracking and muon spectrometers. The heavy-flavor decay muons are further separated into those from charm decay and those from bottom decay using the distance-of-closest-approach to the collision vertex. The measurement is performed for muons in the transverse momentum range 4-7 GeV and pseudorapidity range vertical bar eta vertical bar < 2.4. A significant nonzero elliptic anisotropy coefficient nu(2) is observed for muons from charm decays, while the nu(2) value for muons from bottom decays is consistent with zero within uncertainties. |
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Address |
[Banerjee, S.; Dang, N. P.; Duvnjak, D.; Jackson, P.; Oliver, J. L.; Petridis, A.; Qureshi, A.; Sharma, A. S.; White, M. J.] Univ Adelaide, Dept Phys, Adelaide, SA, Australia |
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Amer Physical Soc |
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ISSN |
0031-9007 |
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Conference |
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Notes |
WOS:000517288800010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4312 |
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LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
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Title |
First Observation of the Doubly Charmed Baryon Decay Xi(++)(cc) -> Xi(+)(c)pi(+) |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
121 |
Issue |
16 |
Pages |
162002 - 10pp |
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Keywords |
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Abstract |
The doubly charmed baryon decay Xi(++)(cc) -> Xi(+)(c)pi(+) is observed for the first time, with a statistical significance of 5.9 sigma, confirming a recent observation of the baryon in the Lambda K-+(c)-pi(+)pi(+) final state. The data sample used corresponds to an integrated luminosity of 1.7 fb(-1), collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV. The Xi(++)(cc) mass is measured to be 3620.6 +/- 1.5(stat) +/- 0.4(syst) +/- 0.3(Xi(+)(c)) MeV/c(2) and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be [B(Xi(++)(cc) -> Xi(+)(c)pi(+)) x B(Xi(+)(c) -> pK(-)pi(+))]/[B(Xi(++)(cc) -> Lambda K-+(c)-pi(+)pi(+)) x B(Lambda(+)(c) -> pK(-)pi(+))] = 0.035 +/- 0.009 (stat) +/- 0.003 (syst). |
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Address |
[Bediaga, I.; Torres, M. Cruz; De Miranda, J. M.; Gomes, A.; Massafferri, A.; Molina Rodriguez, J.; Petruzzo, M.; dos Reis, A. C.; Soares Lavra, I.; Jadallah Aoude, R. Tourinho] CBPF, Rio De Janeiro, Brazil |
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Amer Physical Soc |
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English |
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0031-9007 |
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Notes |
WOS:000447486300010 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3765 |
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Author |
LHCb Collaboration (Aaij, R. et al); Martinez-Vidal, F.; Oyanguren, A.; Ruiz Valls, P.; Sanchez Mayordomo, C. |
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Title |
First Measurement of the Charge Asymmetry in Beauty-Quark Pair Production |
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 |
8 |
Pages |
082003 - 9pp |
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Keywords |
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Abstract |
The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in b (b) over bar pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(-1) collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the b (b) over bar system. The results obtained are A(C)(b (b) over bar) (40 < M-b<(b)over bar> < 75 GeV/c(2)) = 0.4 +/- 0.4 +/- 0.3%, A(C)(b (b) over bar) (75 < M-b<(b)over bar> < 105 GeV/c(2)) = 2.0 +/- 0.9 +/- 0.6%, A(C)(b (b) over bar) (M-b (b) over bar > 10(5) GeV/c(2)) = 1.6 +/- 1.7 +/- 0.6%,where A(C)(b (b) over bar) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 < eta < 4, E-T > 20 GeV, and have an opening angle in the transverse plane Delta phi > 2.6 rad. These measurements are consistent with the predictions of the standard model. |
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Address |
[Bediaga, I.; De Miranda, J. M.; Rodrigues, F. Ferreira; Gomes, A.; Hicheur, A.; Massafferri, A.; dos Reis, A. C.; Rodrigues, A. B.] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil |
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Amer Physical Soc |
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English |
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ISSN |
0031-9007 |
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Notes |
WOS:000346504200005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2045 |
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Author |
LHCb Collaboration (Aaij, R. et al); Garcia Martin, L.M.; Henry, L.; Martinez-Vidal, F.; Oyanguren, A.; Remon Alepuz, C.; Ruiz Valls, P.; Ruiz Vidal, J.; Sanchez Mayordomo, C. |
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Title |
chi(c1) and chi(c2) Resonance Parameters with the Decays chi(c1,c2) -> J/psi mu(+)mu(-) |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
119 |
Issue |
22 |
Pages |
221801 - 9pp |
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Keywords |
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Abstract |
The decays chi(c1) -> J/psi mu(+)mu(-) and chi(c1) -> J/psi mu(+)mu(-) are observed and used to study the resonance parameters of the chi(c1) and chi(c2) mesons. The masses of these states are measured to be m(chi(c1)) = 3510.71 +/- 0.04(stat) +/- 0.09(syst) MeV and m(chi(c2)) = 3556.10 +/- 0.06(stat) +/- 0.11(syst) MeV, where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m(chi(c2)) – m(chi(c1)) = 45.39 +/- 0.07(stat) +/- 0.03(syst) MeV. The natural width of the chi(c2) meson is measured to be Gamma(chi(c2)) = 2.10 +/- 0.20(stat) +/- 0.02(syst) MeV. These results are in good agreement with and have comparable precision to the current world averages. |
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Address |
[Bediaga, I.; Cruz Torres, M.; De Miranda, J. M.; Gomes, A.; Massafferri, A.; Molina Rodriguez, J.; dos Reis, A. C.; Rodrigues, A. B.; Salustino Guimaraes, V.; Soares Lavra, L.; Tourinho Jadallah Aoude, R.] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil |
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Publisher |
Amer Physical Soc |
Place of Publication |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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Series Issue |
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ISSN |
0031-9007 |
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Conference |
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Notes |
WOS:000416317900008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3389 |
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