A search for time-integrated CP violation in the Cabibbo-suppressed decay $D^0topi^-pi^+pi^0$ is performed using for the first time an unbinned model-independent technique known as the energy test. Using proton-proton collision data, corresponding to
an integrated luminosity of 2.0 fb$^{-1}$ collected by the LHCb detector at a centre-of-mass energy of $sqrt{s}$ = 8 TeV, the worlds best sensitivity to CP violation in this decay is obtained. The data are found to be consistent with the hypothesis of CP symmetry with a p-value of (2.6 +/- 0.5)%.
A study of indirect CP violation in $D^0$ mesons through the determination of the parameter $A_Gamma$ is presented using a data sample of $pp$ collisions, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector an
d recorded at the centre-of-mass energy of 7 TeV at the LHC. The parameter $A_Gamma$ is the asymmetry of the effective lifetimes measured in decays of $D^0$ and $bar{D}^0$ mesons to the CP eigenstates $K^-K^+$ and $pi^-pi^+$. Fits to the data sample yield $A_Gamma(KK)=(-0.35pm0.62pm0.12)times 10^{-3}$ and $A_Gamma(pipi)=(0.33pm1.06pm0.14)times 10^{-3}$, where the first uncertainties are statistical and the second systematic. The results represent the worlds best measurements of these quantities. They show no difference in $A_Gamma$ between the two final states and no indication of CP violation.
A study of mixing and indirect CP violation in D0 mesons through the determination of the parameters y_CP and A_Gamma is presented. The parameter y_CP is the deviation from unity of the ratio of effective lifetimes measured in D0 decays to the CP eig
enstate K+K- with respect to decays to the Cabibbo favoured mode K-pi+. The result measured using data collected by LHCb in 2010, corresponding to an integrated luminosity of 29 pb^-1, is y_CP = (5.5+/-6.3_{stat}+/-4.1_{syst}) x 10^-3. The parameter A_Gamma is the asymmetry of effective lifetimes measured in decays of D0 and anti-D0 mesons to K+K-. The result is A_Gamma = (-5.9+/-5.9_{stat}+/-2.1_{syst}) x 10^-3. A data-driven technique is used to correct for lifetime-biasing effects.
LHCb is one of the four main experiments of the Large Hadron Collider (LHC) project, which will start at CERN in 2008. The experiment is primarily dedicated to B-Physics and hence requires precise vertex reconstruction. The silicon vertex locator (VE
LO) has a single hit precision of better than 10 micron and is used both off-line and in the trigger. These requirements place strict constraints on its alignment. Additional challenges for the alignment arise from the detector being retracted between each fill of the LHC and from its unique circular disc r/phi strip geometry. This paper describes the track based software alignment procedure developed for the VELO. The procedure is primarily based on a non-iterative method using a matrix inversion technique. The procedure is demonstrated with simulated events to be fast, robust and to achieve a suitable alignment precision.
