Three dimensional field theories from infinite dimensional lie algebras

A procedure for constructing topological actions from centrally extended Lie groups is introduced. For a \km\ group, this produces \3al \cs, while for the \vir\ group the result is a new \3al \tft\ whose physical states satisfy the \vir\ \wi. This \tft\ is shown to be a first order formulation of two dimensional induced gravity in the chiral gauge. The extension to $W_3$-gravity is discussed.Comment: 11 pages, USC-92/01

A classical N=4 super W_3 algebra

I construct classical superextensions of the Virasoro algebra by employing the Ward identities of a linearly realized subalgebra. For the $N=4$ superconformal algebra, this subalgebra is generated by the $N=2$ $U(1)$ supercurrent and a spin~0 $N=2$ superfield. I show that this structure can be extended to an $N=4$ super $W_3$ algebra, and give the complete form of this algebra.Comment: 15 pages, USC/92-02

Prospects for New Physics in CP Violation and Rare Decays at LHCb

LHCb is the heavy flavour precision experiment of the proton-proton Large Hadron Collider (LHC) at CERN. It will search for new physics in CP violation and rare decays and is ready for the start-up of the LHC. An overview of its physics program will be given, illustrated by few key examples: measurements of the CKM angle $\gamma$, of the CP violating phase in $B_s \overline{B_s}$ oscillations and searches for new physics in $B^0_d \to K^*\mu^+\mu^-$ and in $B^0_s \to \mu^+\mu^-$.Comment: PANIC08 conference proceedings, 3 page

Status and expected performance of the LHCb experiment

LHCb is a dedicated b-physics experiment at the future LHC collider. Its construction has started and it will be ready to take data from the start of LHC operation, scheduled in 2007, and directly at its full physics potential. LHCb will benefit from an unprecedented source of b-hadrons, provided by LHC, to improve substantialy precision measurements of CP violation parameters in many different and complementary channels. The detector provides good particle identification, vertexing and has an efficient and flexible trigger. Its status and expected performance are reviewed.Comment: 8 pages, 2 figures, To appear in the Proceedings of 6th International Conference on Hyperons, Charm & Beauty Hadrons, Chicago, United States, June 27 -- July 3 200

b Physics

A summary of the most recent and important measurements in b physics is presented. The production of beauty particles in Z decays, b quark couplings, lifetimes, B0-B0bar oscillations, semileptonic b decays and studies of the number of charm quarks produced in b decays are reviewed. Extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements |V_{td}|, |V_{cb}|, |V_{ub}| and implication for |V_{ts}| are discussed.Comment: 24 pages, 2 figures, Second Latin American Symposium on High Energy Physics, San Juan, Puerto Rico, April 199

Computational Particle Physics for Event Generators and Data Analysis

High-energy physics data analysis relies heavily on the comparison between experimental and simulated data as stressed lately by the Higgs search at LHC and the recent identification of a Higgs-like new boson. The first link in the full simulation chain is the event generation both for background and for expected signals. Nowadays event generators are based on the automatic computation of matrix element or amplitude for each process of interest. Moreover, recent analysis techniques based on the matrix element likelihood method assign probabilities for every event to belong to any of a given set of possible processes. This method originally used for the top mass measurement, although computing intensive, has shown its power at LHC to extract the new boson signal from the background. Serving both needs, the automatic calculation of matrix element is therefore more than ever of prime importance for particle physics. Initiated in the eighties, the techniques have matured for the lowest order calculations (tree-level), but become complex and CPU time consuming when higher order calculations involving loop diagrams are necessary like for QCD processes at LHC. New calculation techniques for next-to-leading order (NLO) have surfaced making possible the generation of processes with many final state particles (up to 6). If NLO calculations are in many cases under control, although not yet fully automatic, even higher precision calculations involving processes at 2-loops or more remain a big challenge. After a short introduction to particle physics and to the related theoretical framework, we will review some of the computing techniques that have been developed to make these calculations automatic. The main available packages and some of the most important applications for simulation and data analysis, in particular at LHC will also be summarized.Comment: 19 pages, 11 figures, Proceedings of CCP (Conference on Computational Physics) Oct. 2012, Osaka (Japan) in IOP Journal of Physics: Conference Serie