179 research outputs found
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Effects of plant population density on cabbage (Brassica oleracea var. capitata L.) crop
Com a finalidade de avaliar o efeito da densidade de população de plantas sobre a cultura de repolho (Brassica cleraoea var, capitata L.), foi realizado um experimento no Campo Experimental do Setor de Horticultura da Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba, São Paulo, em um Latossol Roxo, Série Luiz de Queiroz, utilizando-se os espaçamentos de 0,60 mx 0,80 m; 0,60 m x 0,65 m; 0,60 m x 0,45 m; 0,60 m x 0,30 m e 0,60 m x 0,15 m. à medida em que se aumentou a densidade de população, houve as seguintes alteraçÔes na planta de repolho: mudança de for mato chato da "cabeça" para cÎnico, redução do numero de folhas, tamanho (peso, volume e diùmetros transversal e longitudinal) , aumento na densidade da "cabeça" (peso/volume) e aumento na porcentagem de plantas que não produziram "cabeça.In order to study the effects of plant population density on cabbage crop (Brassica oleracea var-. capitata), an experiment using different spacing (0,60 m x 0.80 m, 0.60 m x 0.65 m, 0.60mx0.45m, 0.60 m x 0.30 m, and 0.60mx 0.15m) was carried out. There were the following changes in cabbage plants due to increasing population density: plant head became conical: number and size (weight, volume and diameters) of leaves decreased; density (weight/volume) and percentage of plants forming no head increased
Identification of beauty and charm quark jets at LHCb
Identification of jets originating from beauty and charm quarks is important
for measuring Standard Model processes and for searching for new physics. The
performance of algorithms developed to select - and -quark jets is
measured using data recorded by LHCb from proton-proton collisions at
TeV in 2011 and at TeV in 2012. The efficiency for
identifying a jet is about 65%(25%) with a probability for
misidentifying a light-parton jet of 0.3% for jets with transverse momentum
GeV and pseudorapidity . The dependence of
the performance on the and of the jet is also measured
Search for Bâșc decays to the ppâŸÏâș final state
A search for the decays of the B + c meson to pp-Ï + is performed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb -1 collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV. No signal is found and an upper limit, at 95% confidence level, is set, fcfuĂB(B + c âppÏ + ) < 3.6Ă10-8 in the kinematic region m(pp) < 2.85 GeV/c2, p T (B) < 20 GeV/c and 2.0 < y(B) < 4.5, where B is the branching fraction and f c (f u ) is the fragmentation fraction of the b quark into a B c + (B + ) meson
Measurement of CP observables in B± â D(â)K± and B± â D(â)ϱ decays
Measurements of CP observables in B ± âD (â) K ± and B ± âD (â) Ï Â± decays are presented, where D (â) indicates a neutral D or D â meson that is an admixture of D (â)0 and DÂŻ (â)0 states. Decays of the D â meson to the DÏ 0 and DÎł final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the B candidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K ± Ï â , K + K â and Ï + Ï â final states. The analysis uses a sample of charged B mesons produced in pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb â1 taken at centre-of-mass energies of s=7, 8 and 13 TeV, respectively. The study of B ± âD â K ± and B ± âD â Ï Â± decays using a partial reconstruction method is the first of its kind, while the measurement of B ± âDK ± and B ± âDÏ Â± decays is an update of previous LHCb measurements. The B ± âDK ± results are the most precise to date
Observation of the decay B0s â Ï(2S)K +Ïâ
The decay B0
s â Ï(2S)K +Ïâ is observed using a data set corresponding to an integrated luminosity of
3.0 fbâ1 collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV.
The branching fraction relative to the B0 â Ï(2S)K +Ïâ decay mode is measured to be
B(B0
s â Ï(2S)K +Ïâ)
B(B0 â Ï(2S)K +Ïâ) = 5.38 ± 0.36 (stat) ± 0.22 (syst) ± 0.31 (f s/ fd)%,
where f s/ fd indicates the uncertainty due to the ratio of probabilities for a b quark to hadronise into
a B0
s or B0 meson. Using an amplitude analysis, the fraction of decays proceeding via an intermediate
Kâ(892)0 meson is measured to be 0.645 ± 0.049 (stat) ± 0.049 (syst) and its longitudinal polarisation
fraction is 0.524 ± 0.056 (stat) ± 0.029 (syst). The relative branching fraction for this component is
determined to be
B(B0
s â Ï(2S)Kâ(892)0)
B(B0 â Ï(2S)Kâ(892)0) = 5.58 ± 0.57 (stat) ± 0.40 (syst) ± 0.32 (f s/ fd)%.
In addition, the mass splitting between the B0
s and B0 mesons is measured as
M(B0
s ) â M(B0) = 87.45 ± 0.44 (stat) ± 0.09 (syst) MeV/c2
Observation of the B0 â Ï0Ï0 decay from an amplitude analysis of B0 â (Ï+Ïâ)(Ï+Ïâ) decays
Protonâproton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to
an integrated luminosity of 3.0 fbâ1, are analysed to search for the charmless B0 â Ï0Ï0 decay.
More than 600 B0 â (Ï+Ïâ)(Ï+Ïâ) signal decays are selected and used to perform an amplitude
analysis, under the assumption of no CP violation in the decay, from which the B0 â Ï0Ï0 decay is
observed for the first time with 7.1 standard deviations significance. The fraction of B0 â Ï0Ï0 decays
yielding a longitudinally polarised final state is measured to be fL = 0.745+0.048
â0.058(stat) ± 0.034(syst).
The B0 â Ï0Ï0 branching fraction, using the B0 â ÏKâ(892)0 decay as reference, is also reported as
B(B0 â Ï0Ï0) = (0.94 ± 0.17(stat) ± 0.09(syst) ± 0.06(BF)) Ă 10â6
Measurement of the CP-violating phase ÎČ in B0 â J/ÏÏ+Ïâ decays and limits on penguin effects
Time-dependent CP violation is measured in the (â)
B 0 â J/ÏÏ+Ïâ channel for each Ï+Ïâ resonant
final state using data collected with an integrated luminosity of 3.0 fbâ1 in pp collisions using the LHCb
detector. The final state with the largest rate, J/ÏÏ0(770), is used to measure the CP-violating angle
2ÎČeff to be (41.7 ± 9.6+2.8
â6.3)âŠ. This result can be used to limit the size of penguin amplitude contributions
to CP violation measurements in, for example, (â)
B 0
s â J/ÏÏ decays. Assuming approximate SU(3) flavour
symmetry and neglecting higher order diagrams, the shift in the CP-violating phase Ïs is limited to be
within the interval [â1.05âŠ,+1.18âŠ] at 95% confidence level. Changes to the limit due to SU(3) symmetry
breaking effects are also discussed
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