Search for CP violation in the Bs/Bs-bar system

We present studies from the LHCb experiment leading to the measurement of the weak phase {\phi}s. At first, flavor tagging is established by measuring the B0s oscillation frequency \Deltams. Then, flavor tagging is used to perform a measurement of the well known CKM angle sin 2{\beta} in B0 \rightarrow J/{\psi} KS0, before we constrain {\phi}s through an amplitude analysis of B0s \rightarrow J/{\psi} {\phi} decays. These studies use about 35 inverse pb of data taken in 2010. In addition, we present the measurement of B(B+\rightarrowJ/{\psi}{\pi}+)/B(B+\rightarrowJ/{\psi}K+) and the first observation of B0s \rightarrowJ/{\psi}f2'(1525).Comment: 3 pages, 6 figures, The 19th Particles & Nuclei International Conference (PANIC11), MIT, Boston, July 24th-29th, 201

Using a new multivariate technique in high energy physics

This project focuses on testing and developing algorithms for multivariate data analysis, that separate signal processes from abundant backgrounds and on helping with organizing and filtering colossal amounts of raw data, gathered from the Large Hadron Collider beauty (LHCb) experiment, to find extremely rare events of interest. Moreover, working on this project also meant trying to apply new, faster method to take the place of systems that are now used at CERN to pare down the relevant data, but require relatively extensive processing and analysis to determine relevance and usefulness

Improved constraints on γ\gamma: CKM2014 update

I report on an updated combination of all currently available tree-level measurements of the CKM angle $\gamma$ from LHCb. This combination currently gives LHCb's most precise value of $\gamma = (73^{+9}_{-10})^\circ$ obtained from $B\to DK$-like decays. For the first time in a single experiment, the uncertainty has dropped below $10^\circ$. When using $B\to D\pi$ decays in addition, the situation becomes more difficult to interpret.Comment: on behalf of the LHCb collaboration. Proceedings of the 8th International Workshop on the CKM Unitarity Triangle (CKM 2014), Vienna, Austria, September 8-12, 201

Measurement of CP violation parameters and polarisation fractions in Bs0→J/ψK‾∗0 {\mathrm{B}}_{\mathrm{s}}^0\to \mathrm{J}/\psi {\overline{\mathrm{K}}}^{\ast 0} decays

The first measurement of ${C\!P}$ asymmetries in the decay ${B_s^0\to J/\psi \overline{K}^{*}(892)^{0}}$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of $3.0\,fb^{-1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of $7$ and $8\,\mathrm{TeV}$. Together with constraints from ${B^0\to J/\psi \rho^0}$, the results are used to constrain additional contributions due to penguin diagrams in the ${C\!P}$-violating phase ${{\phi}_{s}}$, measured through ${B_s^0}$ decays to charmonium.The first measurement of CP asymmetries in the decay ${B}_s^0\to J/\psi {\overline{\mathrm{K}}}^{\ast }{(892)}^0$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb^{−}^{1} of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. Together with constraints from B$^{0}$ → J/ψ ρ$^{0}$, the results are used to constrain additional contributions due to penguin diagrams in the CP -violating phase ϕ$_{s}$ , measured through B$_{s}^{0}$ decays to charmonium.The first measurement of ${C\!P}$ asymmetries in the decay ${B_s^0\to J/\psi \overline{K}^{*}(892)^{0}}$ and an updated measurement of its branching fraction and polarisation fractions are presented. The results are obtained using data corresponding to an integrated luminosity of $3.0\,fb^{-1}$ of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of $7$ and $8\,\mathrm{TeV}$. Together with constraints from ${B^0\to J/\psi \rho^0}$, the results are used to constrain additional contributions due to penguin diagrams in the ${C\!P}$-violating phase ${{\phi}_{s}}$, measured through ${B_s^0}$ decays to charmonium

Search for the lepton flavour violating decay tau(-) -> mu(-)mu(+)mu(-)

A search for the lepton flavour violating decay $\tau^-\rightarrow\mu^-\mu^+\mu^-$ is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0 fb$^{−1}$ of proton-proton collisions at a centre-of-mass energy of 7 TeV and 2.0 fb$^{−1}$ at 8 TeV. No evidence is found for a signal, and a limit is set at 90% confidence level on the branching fraction, $\mathcal{B}(\tau^-\rightarrow\mu^-\mu^+\mu^-)<4.6\times10^{−8}$.A search for the lepton flavour violating decay τ$^{−}$ → μ$^{−}$ μ$^{+}$ μ$^{−}$ is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of 1.0 fb$^{−1}$ of proton-proton collisions at a centre-of-mass energy of 7 TeV and 2.0 fb$^{−1}$ at 8 TeV. No evidence is found for a signal, and a limit is set at 90% confidence level on the branching fraction, $\mathrm{\mathcal{B}}\left({\tau}^{-}\to {\mu}^{-}{\mu}^{+}{\mu}^{-}\right)<4.6\times {10}^{-8}$ .A search for the lepton flavour violating decay $\tau^-\to \mu^-\mu^+\mu^-$ is performed with the LHCb experiment. The data sample corresponds to an integrated luminosity of $1.0\mathrm{\,fb}^{-1}$ of proton-proton collisions at a centre-of-mass energy of $7\mathrm{\,Te\kern -0.1em V}$ and $2.0\mathrm{\,fb}^{-1}$ at $8\mathrm{\,Te\kern -0.1em V}$. No evidence is found for a signal, and a limit is set at $90\%$ confidence level on the branching fraction, $\mathcal{B}(\tau^-\to \mu^-\mu^+\mu^-) < 4.6 \times 10^{-8}$