8,519 research outputs found
Entropy production and Kullback-Leibler divergence between stationary trajectories of discrete systems
The irreversibility of a stationary time series can be quantified using the
Kullback-Leibler divergence (KLD) between the probability to observe the series
and the probability to observe the time-reversed series. Moreover, this KLD is
a tool to estimate entropy production from stationary trajectories since it
gives a lower bound to the entropy production of the physical process
generating the series. In this paper we introduce analytical and numerical
techniques to estimate the KLD between time series generated by several
stochastic dynamics with a finite number of states. We examine the accuracy of
our estimators for a specific example, a discrete flashing ratchet, and
investigate how close is the KLD to the entropy production depending on the
number of degrees of freedom of the system that are sampled in the
trajectories.Comment: 14 pages, 7 figure
First evidence of direct CP violation in charmless two-body decays of Bs0 mesons
Using a data sample corresponding to an integrated luminosity of 0.35ââfb-1 collected by LHCb in 2011, we report the first evidence of CP violation in the decays of Bs0 mesons to K±Ïâ pairs, ACP(Bs0âKÏ)= 0.27±0.08(stat)±0.02(syst), with a significance of 3.3Ï. Furthermore, we report the most precise measurement of CP violation in the decays of B0 mesons to K±Ïâ pairs, ACP(B0âKÏ)=-0.088±0.011(stat)±0.008(syst), with a significance exceeding 6Ï
Strong constraints on the rare decays Bs0 -> Ό+Ό- and B0 -> Ό+Ό-
A search for Bs0âÎŒ+ÎŒ- and B0âÎŒ+ÎŒ- decays is performed using 1.0ââfb-1 of pp collision data collected at âs=7ââTeV with the LHCb experiment at the Large Hadron Collider. For both decays, the number of observed events is consistent with expectation from background and standard model signal predictions. Upper limits on the branching fractions are determined to be B(Bs0âÎŒ+ÎŒ-)<4.5(3.8)Ă10-9 and B(B0âÎŒ+ÎŒ-)<1.0(0.81)Ă10-9 at 95% (90%) confidence level
Measurement of b-hadron branching fractions for two-body decays into charmless charged hadrons
Based on data corresponding to an integrated luminosity of 0.37 fbâ1 collected by the LHCb experiment in 2011, the following ratios of branching fractions are measured: B(B0âÏ+Ïâ)/B(B0âK+Ïâ)=0.262±0.009±0.017,(fs/fd)â
B(B0sâK+Kâ)/B(B0âK+Ïâ)=0.316±0.009±0.019,(fs/fd)â
B(B0sâÏ+Kâ)/B(B0âK+Ïâ)=0.074±0.006±0.006,(fd/fs)â
B(B0âK+Kâ)/B(B0sâK+Kâ)=0.018+0.008â0.007±0.009,(fs/fd)â
B(B0sâÏ+Ïâ)/B(B0âÏ+Ïâ)=0.050+0.011â0.009±0.004,B(Î0bâpÏâ)/B(Î0bâpKâ)=0.86±0.08±0.05, where the first uncertainties are statistical and the second systematic. Using the current world average of B(B0âK+Ïâ) and the ratio of the strange to light neutral B meson production f s /f d measured by LHCb, we obtain: B(B0âÏ+Ïâ)=(5.08±0.17±0.37)Ă10â6,B(B0sâK+Kâ)=(23.0±0.7±2.3)Ă10â6,B(B0sâÏ+Kâ)=(5.4±0.4±0.6)Ă10â6,B(B0âK+Kâ)=(0.11+0.05â0.04±0.06)Ă10â6,B(B0sâÏ+Ïâ)=(0.95+0.21â0.17±0.13)Ă10â6.
The measurements of B(B0sâK+Kâ) , B(B0sâÏ+Kâ) and B(B0âK+Kâ) are the most precise to date. The decay mode B0sâÏ+Ïâ is observed for the first time with a significance of more than 5Ï
Measurement of relative branching fractions of B decays to Ï(2S) and J/Ï mesons
The relative rates of B-meson decays into J/Ï
and Ï(2S) mesons are measured for the three decay modes
in pp collisions recorded with the LHCb detector. The ratios
of branching fractions (B) are measured to be
B(B
+âÏ(2S)K
+
)
B(B+âJ/ÏK+)
= 0.594±0.006(stat)±0.016(syst)±0.015(RÏ),
B(B0âÏ(2S)K
â0)
B(B0âJ/ÏKâ0)
= 0.476±0.014(stat)±0.010(syst)±0.012(RÏ),
B(B0
s
âÏ(2S)Ï)
B(B0
s
âJ/ÏÏ)
= 0.489±0.026(stat)±0.021(syst)±0.012(RÏ),
where the third uncertainty is from the ratio of the Ï(2S)
and J/Ï branching fractions to ÎŒ
+
Ό
â.
1 Introductio
Search for the rare decays B0sâÎŒ+ÎŒâ and B0âÎŒ+ÎŒâ
A search for the decays and B0âÎŒ+ÎŒâ is performed with 0.37 fbâ1 of pp collisions at collected by the LHCb experiment in 2011. The upper limits on the branching fractions are and B(B0âÎŒ+ÎŒâ)<3.6Ă10â9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to and B(B0âÎŒ+ÎŒâ)<3.2Ă10â9 at 95% confidence level
Searches for Majorana neutrinos in B-decays
Searches for heavy Majorana neutrinos in B- decays in final states containing hadrons plus a ÎŒ-ÎŒ- pair have been performed using 0.41ââfb-1 of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. The D+ÎŒ-ÎŒ- and D*+ÎŒ-ÎŒ- final states can arise from the presence of virtual Majorana neutrinos of any mass. Other final states containing Ï+, Ds+, or D0Ï+ can be mediated by an on-shell Majorana neutrino. No signals are found and upper limits are set on Majorana neutrino production as a function of mass, and also on the B- decay branching fractions
Measurements of Bc+ production and mass with the Bc+ -> J/ΚÏ+ decay
Measurements of B-c(+) production and mass are performed with the decay mode B-c(+) -> J/psi pi(+) using 0.37 fb(-1) of data collected in pp collisions at root s = 7 TeV by the LHCb experiment. The ratio of the production cross section times branching fraction between the B-c(+) -> J/psi pi(+) and the B+ -> J/psi K+ decays is measured to be (0.68 +/- 0.10(stat) +/- 0.03(syst) +/- 0.05(lifetime))% for B-c(+) and B+ mesons with transverse momenta p(T) > 4 GeV/c and pseudorapidities 2.5 < eta < 4.5. The B-c(+) mass is directly measured to be 6273.7 +/- 1.3(stat) +/- 1.6(syst) MeV/c(2), and the measured mass difference with respect to the B+ meson is M(B-c(+)) - M(B+) = 994.6 +/- 1.3(stat) +/- 0.6(syst) MeV/c(2)
Measurement of the forward energy flow in pp collisions at âs=7 TeV
The energy flow created in pp collisions at âs = 7 TeV is studied within the pseudorapidity range 1.9 < η < 4.9 with data collected by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to predictions given by PYTHIA-based and cosmic-ray event generators, which provide different models of soft hadronic interactions
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