A New Exponent Characterizing the Effect of Evaporation on Imbibition Experiments

We report imbibition experiments investigating the effect of evaporation on the interface roughness and mean interface height. We observe a new exponent characterizing the scaling of the saturated surface width. Further, we argue that evaporation can be usefully modeled by introducing a gradient in the strength of the disorder, in analogy with the gradient percolation model of Sapoval {\it et~al.}. By incorporating this gradient we predict a new critical exponent and a novel scaling relation for the interface width. Both the exponent value and the form of the scaling agree with the experimental results.Comment: 12 pages, REVTeX 3.0, figures on request (accepted for PRL

Observation of the decay B+c→Bºsπ+

The result of a search for the decay B+c→Bºsπ+ is presented, using the Bºs→Ds-π+ and Bºs→J/ψϕ channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1  fb-1 taken at a center-of-mass energy of 7 TeV, and 2  fb-1 taken at 8 TeV. The decay B+c→Bºsπ+ is observed with significance in excess of 5 standard deviations independently in both decay channels. The measured product of the ratio of cross sections and branching fraction is [σ(Bc+)/σ(Bºs)]×B(Bc+→Bºsπ+)=[2.37±0.31 (stat)±0.11 (syst)-0.13+0.17(τBc+)]×10-3, in the pseudorapidity range 2<η(B)<5, where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the Bc+ lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction

Observation of B0->D0K+K- and evidence for Bs0->D0K+K-

The first observation of the decay B0→D0K+K- is reported from an analysis of 0.62  fb-1 of pp collision data collected with the LHCb detector. Its branching fraction is measured relative to that of the topologically similar decay B0→D0π+π- to be B(B0→D0K+K-)/B(B0→D0π+π-)=0.056±0.011±0.007, where the first uncertainty is statistical and the second is systematic. The significance of the signal is 5.8σ. Evidence, with 3.8σ significance, for Bs0→D0K+K- decays is also presented. The relative branching fraction is measured to be B(Bs0→D0K+K-)/B(B0→D0K+K-)=0.90±0.27±0.20. These channels are of interest to study the mechanisms behind hadronic B decays, and open new possibilities for CP violation analyses with larger data sets

First evidence of direct CP violation in charmless two-body decays of Bs0 mesons

Using a data sample corresponding to an integrated luminosity of 0.35  fb-1 collected by LHCb in 2011, we report the first evidence of CP violation in the decays of Bs0 mesons to K±π∓ pairs, ACP(Bs0→Kπ)= 0.27±0.08(stat)±0.02(syst), with a significance of 3.3σ. Furthermore, we report the most precise measurement of CP violation in the decays of B0 mesons to K±π∓ pairs, ACP(B0→Kπ)=-0.088±0.011(stat)±0.008(syst), with a significance exceeding 6σ

First observation of the decays B0 -> D+K-π+π- and B- -> D0K-π+π-

First observations of the Cabibbo-suppressed decays B0→D+K-π+π- and B-→D0K-π+π- are reported using 35pb -1 of data collected with the LHCb detector. Their branching fractions are measured with respect to the corresponding Cabibbo-favored decays, from which we obtain B(B0→D+K-π+π-)/B(B0→D+π-π+π-)=(5.9±1.1±0.5) ×10-2 and B(B-→D0K-π+π-)/B(B-→D0π-π+π-)=(9.4±1.3±0.9) ×10-2, where the uncertainties are statistical and systematic, respectively. The B-→D0K-π+π- decay is particularly interesting, as it can be used in a similar way to B-→D0K- to measure the Cabibbo-Kobayashi-Maskawa phase γ

Measurement of the Bs0-Bs0 oscillation frequency δms in Bs0→Ds-(3)π decays

The Bs0-Bs0 oscillation frequency δms is measured with 36 pb-1 of data collected in pp collisions at s=7TeV by the LHCb experiment at the Large Hadron Collider. A total of 1381 Bs0→Ds-π+ and Bs0→Ds-π+π-π + signal decays are reconstructed, with average decay time resolutions of 44 fs and 36 fs, respectively. An oscillation signal with a statistical significance of 4.6σ is observed. The measured oscillation frequency is δm s=17.63±0.11(stat)±0.02(syst)ps -1

Measurement of form-factor-independent observables in the decay B0→K*0μ+μ-

We present a measurement of form-factor-independent angular observables in the decay B0→K*(892)0μ+μ-. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0  fb-1, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 7 TeV. Four observables are measured in six bins of the dimuon invariant mass squared q2 in the range 0.1<q2<19.0  GeV2/c4. Agreement with recent theoretical predictions of the standard model is found for 23 of the 24 measurements. A local discrepancy, corresponding to 3.7 Gaussian standard deviations is observed in one q2 bin for one of the observables. Considering the 24 measurements as independent, the probability to observe such a discrepancy, or larger, in one is 0.5%

Observation of B ̄ (s) 0 → J / ψ f 1 (1285) decays and measurement of the f 1 (1285) mixing angle

Decays of B̄s0 and B̄0 mesons into J/ψ π+π-π+π- final states, produced in pp collisions at the LHC, are investigated using data corresponding to an integrated luminosity of 3 fb-1 collected with the LHCb detector. B̄(s)0→J/ψf1(1285) decays are seen for the first time, and the branching fractions are measured. Using these rates, the f1(1285) mixing angle between strange and nonstrange components of its wave function in the qq̄ structure model is determined to be ±(24.0-2.6-0.8+3.1+0.6). Implications on the possible tetraquark nature of the f1(1285) are discussed

Measurements of indirect CP asymmetries in D0→K−K+ and D0→π−π+ decays

A study of indirect CP violation in D0 mesons through the determination of the parameter AΓ is presented using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0  fb−1, collected with the LHCb detector and recorded at the center-of-mass energy of 7 TeV at the LHC. The parameter AΓ is the asymmetry of the effective lifetimes measured in decays of D0 and D¯​0 mesons to the CP eigenstates K−K+ and π−π+. Fits to the data sample yield AΓ(KK)=(−0.35±0.62±0.12)×10−3 and AΓ(ππ)=(0.33±1.06±0.14)×10−3, where the first uncertainties are statistical and the second systematic. The results represent the world’s best measurements of these quantities. They show no difference in AΓ between the two final states and no indication of CP violation

Measurement of Dº-D-º mixing parameters and search for CP violation using Dº → K+ π- decays

Measurements of charm mixing parameters from the decay-time-dependent ratio of Dº → K+ π- to Dº → K- π+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3  fb−1 of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP ) symmetry, the mixing parameters are determined to be x'2=(5.5±4.9)×10−5, y′=(4.8±1.0)×10−3, and RD=(3.568±0.066)×10−3. Allowing for CP violation, the measurement is performed separately for D0 and D¯¯¯0 mesons yielding AD=(−0.7±1.9)%, for the direct CP-violating asymmetry, and 0.75<|q/p|<1.24 at the 68.3% confidence level, for the parameter describing CP violation in mixing. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation