23 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
Measurement of the branching fraction and angular amplitudes
A search for the decay with is performed with 0.37 fb of collisions at
= 7 TeV collected by the LHCb experiment, finding a \Bs \to J\psi
K^-\pi^+ peak of signal events. The mass spectrum of
the candidates in the peak is dominated by the contribution.
Subtracting the non-resonant component, the branching fraction of
\BsJpsiKst is , where the first
uncertainty is statistical and the second systematic. A fit to the angular
distribution of the decay products yields the \Kst polarization fractions and
Measurement of Upsilon production in pp collisions at \sqrt{s} = 7 TeV
The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons in
proton-proton collisions at the centre-of-mass energy of sqrt(s)=7 TeV is
studied with the LHCb detector. The analysis is based on a data sample of 25
pb-1 collected at the Large Hadron Collider. The Upsilon mesons are
reconstructed in the decay mode Upsilon -> mu+ mu- and the signal yields are
extracted from a fit to the mu+ mu- invariant mass distributions. The
differential production cross-sections times dimuon branching fractions are
measured as a function of the Upsilon transverse momentum pT and rapidity y,
over the range pT < 15 GeV/c and 2.0 < y < 4.5. The cross-sections times
branching fractions, integrated over these kinematic ranges, are measured to be
sigma(pp -> Upsilon(1S) X) x B(Upsilon(1S)->mu+ mu-) = 2.29 {\pm} 0.01 {\pm}
0.10 -0.37 +0.19 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S)->mu+ mu-) =
0.562 {\pm} 0.007 {\pm} 0.023 -0.092 +0.048 nb, sigma(pp -> Upsilon(3S) X) x
B(Upsilon(3S)->mu+ mu-) = 0.283 {\pm} 0.005 {\pm} 0.012 -0.048 +0.025 nb, where
the first uncertainty is statistical, the second systematic and the third is
due to the unknown polarisation of the three Upsilon states.Comment: 22 pages, 7 figure
Evidence for CP violation in time-integrated D0 -> h-h+ decay rates
A search for time-integrated CP violation in D0 -> h-h+ (h=K, pi) decays is
presented using 0.62 fb^-1 of data collected by LHCb in 2011. The flavor of the
charm meson is determined by the charge of the slow pion in the D*+ -> D0 pi+
and D*- -> D0bar pi- decay chains. The difference in CP asymmetry between D0 ->
K-K+ and D0 -> pi-pi+, Delta ACP = ACP(K-K+) - ACP(pi-pi+), is measured to be
[-0.82 \pm 0.21(stat.) \pm 0.11(syst.)]%. This differs from the hypothesis of
CP conservation by 3.5 standard deviations.Comment: 8 pages, 3 figures, 2 tables; v2 minor updates after journal revie
An update in the structure, function, and regulation of V-ATPases: the role of the C subunit
Vacuolar ATPases (V-ATPases) are present in specialized proton secretory cells in which they pump protons across the membranes of various intracellular organelles and across the plasma membrane. The proton transport mechanism is electrogenic and establishes an acidic pH and a positive transmembrane potential in these intracellular and extracellular compartments. V-ATPases have been found to be practically identical in terms of the composition of their subunits in all eukaryotic cells. They have two distinct structures: a peripheral catalytic sector (V1) and a hydrophobic membrane sector (V0) responsible for driving protons. V-ATPase activity is regulated by three different mechanisms, which control pump density, association/dissociation of the V1 and V0 domains, and secretory activity. The C subunit is a 40-kDa protein located in the V1 domain of V-ATPase. The protein is encoded by the ATP6V1C gene and is located at position 22 of the long arm of chromosome 8 (8q22.3). The C subunit has very important functions in terms of controlling the regulation of the reversible dissociation of V-ATPases
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