14 research outputs found
Model-independent evidence for contributions to decays
The data sample of decays acquired with the
LHCb detector from 7 and 8~TeV collisions, corresponding to an integrated
luminosity of 3 fb, is inspected for the presence of or
contributions with minimal assumptions about
contributions. It is demonstrated at more than 9 standard deviations that
decays cannot be described with
contributions alone, and that contributions play a dominant role in
this incompatibility. These model-independent results support the previously
obtained model-dependent evidence for charmonium-pentaquark
states in the same data sample.Comment: 21 pages, 12 figures (including the supplemental section added at the
end
Quantum numbers of the state and orbital angular momentum in its decay
Angular correlations in decays, with , and , are used to measure
orbital angular momentum contributions and to determine the value of
the meson. The data correspond to an integrated luminosity of 3.0
fb of proton-proton collisions collected with the LHCb detector. This
determination, for the first time performed without assuming a value for the
orbital angular momentum, confirms the quantum numbers to be .
The is found to decay predominantly through S wave and an upper limit
of at C.L. is set on the fraction of D wave.Comment: 16 pages, 4 figure
Observation of Z production in proton-lead collisions at LHCb
The first observation of Z boson production in proton-lead collisions at a centre-of-mass energy per proton-nucleon pair of root(s) N N = 5TeV is presented. The data sample corresponds to an integrated luminosity of 1.6 nb(-1) collected with the LHCb detector. The Z candidates are reconstructed from pairs of oppositely charged muons with pseudorapidities between 2.0 and 4.5 and transverse momenta above 20 GeV/c. The invariant dimuon mass is restricted to the range 60-120 GeV/c. The Z production cross-section is measured to be sigma(Z ->mu+mu-) (fwd) = 13.5(-4.0)(+5.4)(stat.) +/- 1.2(syst.) nb in the direction of the proton beam and sigma(Z ->mu+mu-) (bwd) = 10.7(-5.1)(+8.4)(stat.) +/- 1.0(syst.) nb in the direction of the lead beam, where the first uncertainty is statistical and the second systematic
Ingreso de micromam\uedferos bras\uedlicos en la provincia de Buenos Aires, argentina
La provincia de Buenos Aires (Argentina) es una de las mejor conocidas en cuanto a sus pequeños mamíferos. Sin embargo, aspectos como la distribución geográfica detallada de algunas especies permanecen pobremente explorados. Entre éstos puede destacarse la penetración de elementos faunísticos brasílicos en el límite sur, aprovechando el corredor Paraná-Plata. En el nordeste de la provincia de Buenos Aires se interdigitan formaciones florísticas correspondientes a la selva marginal, a los bosques xerófilos y comunidades higrófilas de bajíos ribereños. Estos ambientes, muy degradados en su expresión actual por impacto antrópico, se extienden en una angosta franja, próxima al Río de la Plata, facilitando la penetración de mamíferos frecuentes en el Delta del Paraná. En esta nota se documentan los registros mas australes para el marsupial Gracilinanus agilis (Burmeister, 1854) y los roedores sigmodontinos Deltamys kempi Thomas, 1917 y Oligoryzomys delticola (Thomas, 1917).Fil: Udrizar Sauthier, Daniel Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Abba, Agustin Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Pagano, Luis. Universidad Nacional de La Plata; ArgentinaFil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentin
Measurement of CP violation and constraints on the CKM angle γ in B± → DK± with D → K0Sπ+π− decays
A model-dependent amplitude analysis of B± → DK± with D → K0
Sπ+π− decays is performed using
proton–proton collision data, corresponding to an integrated luminosity of 1 fb−1, recorded by LHCb at
a centre-of-mass energy of 7 TeV in 2011. Values of the CP violation observables x± and y±, which are
sensitive to the CKM angle γ, are measured to be
x− = +0.027 ± 0.044+0.010 −0.008 ± 0.001,
y− = +0.013 ± 0.048+0.009 −0.007 ± 0.003,
x+ = −0.084 ± 0.045 ± 0.009 ± 0.005,
y+ = −0.032 ± 0.048+0.010 −0.009 ± 0.008,
where the first uncertainty is statistical, the second systematic and the third arises from the uncertainty of
the D → K0
Sπ+π− amplitude model. The value of γ is determined to be (84+49
−42)◦, including all sources
of uncertainty. Neutral D meson mixing is found to have negligible effect
Observation of Two New Xi(-)(b) Baryon Resonances
Two structures are observed close to the kinematic threshold in the \u39eb0\u3c0- mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0fb-1, recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spin-parity JP=(1/2)+ and JP=(3/2)+ states, denoted \u39eb\u2032- and \u39eb 17-. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(\u39eb\u2032-)-m(\u39eb0)-m(\u3c0-)=3.653\ub10.018\ub10.006MeV/c2, m(\u39eb 17-)-m(\u39eb0)-m(\u3c0-)=23.96\ub10.12\ub10.06MeV/c2, \u393(\u39eb 17-)=1.65\ub10.31\ub10.10MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of \u393(\u39eb\u2032-)<0.08MeV at 95% confidence level. Relative production rates of these states are also reported
Precision Measurement of CP Violation in B-S(0) -> J/Psi K+K- Decays
The time-dependent CP asymmetry in Bs0\u2192J/\u3c8K+K- decays is measured using pp collision data, corresponding to an integrated luminosity of 3.0fb-1, collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. In a sample of 96000 Bs0\u2192J/\u3c8K+K- decays, the CP-violating phase \u3c6s is measured, as well as the decay widths \u393L and \u393H of the light and heavy mass eigenstates of the Bs0-B\uafs0 system. The values obtained are \u3c6s=-0.058\ub10.049\ub10.006rad, \u393s 61(\u393L+\u393H)/2=0.6603\ub10.0027\ub10.0015ps-1, and \u394\u393s 61\u393L-\u393H=0.0805\ub10.0091\ub10.0032ps-1, where the first uncertainty is statistical and the second, systematic. These are the most precise single measurements of those quantities to date. A combined analysis with Bs0\u2192J/\u3c8\u3c0+\u3c0- decays gives \u3c6s=-0.010\ub10.039rad. All measurements are in agreement with the standard model predictions. For the first time, the phase \u3c6s is measured independently for each polarization state of the K+K- system and shows no evidence for polarization dependence
Precision measurement of the Xi(++)(cc) mass
A measurement of the Ξ++cc mass is performed using data collected by the LHCb experiment between 2016 and 2018 in pp collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6 fb−1. The Ξ++cc candidates are reconstructed via the decay modes Ξ++cc→Λ+cK−π+π+ and Ξ++cc→Ξ+cπ+. The result, 3621.55 ± 0.23 (stat) ± 0.30 (syst) MeV/c2, is the most precise measurement of the Ξ++cc mass to date