The MSSM with decoupled scalars at the LHC

The discovery potential for the MSSM with heavy scalars at the LHC in the case of light inos is examined. We discuss the phenomenology of the model and the observables to determine the parameters. We show that for light gauginos, the model parameters can be constrained with a precision of the order of 15%.Comment: contribution to the Electroweak session of the Moriond 2008 conferenc

Measuring Supersymmetry with Heavy Scalars

Supersymmetry with heavy scalars is a model where at the LHC we have to rely on rate measurements to determine the parameters of the underlying new physics. For this example we show how to properly combine rate measurements with kinematic endpoints, taking into account statistical, systematic and theory uncertainties. Provided we observe a sizeable number of events the LHC should be able to determine many model parameters with small enough error bars to for example test unification patterns.Comment: 13 pages, 8 table

Пам’яті Б.К. Термени

In memory of B.K. Termen

Ingénierie de la base roulante

Ce rapport traite des travaux effectués par le PAi n°74. L’objectif de ce PAi est de finaliser la conception démarrée l’année précédente et d’assurer la production et le fonctionnement de la liaison au sol du véhicule STUF’2015 Atomix de l’EPSA en vue d’une participation au Formula Student Italia 2015. Le Formula Student est une compétition automobile, composée de différentes épreuves statiques et dynamiques, regroupant une centaine d’universités européennes. La ligne directrice de la conception du véhicule a été commune aux 4 projets (PE puis PAi) participant à cette réalisation et a permis de réduire la masse du véhicule de 30Kg par rapport au précédent véhicule de l’écurie. La liaison au sol d’un véhicule constitue l’interface entre le reste du véhicule et la route ; elle a été divisée en cinq sous-ensembles, chacun attribué à un membre du groupe. Les sous-ensembles sont : pneu-jante, moyeu-porte moyeu, système de freinage, système de direction et enfin, le système de suspension. Pour chaque sous-système, après avoir retenu le concept à la fin de l’année précédente, la démarche de conception a consisté à fixer de manière définitive la géométrie du système puis à choisir les matériaux utilisés et effectuer le dimensionnement du système. Cette étape a été concrétisée par l’obtention du Top Copeaux déclenchant la production et l’assemblage du véhicule. Une organisation a été mise en place afin de produire et d’approvisionner les différentes pièces aboutissant à l’intégration finale d’Atomix. Des procédures de validation et d’essais ont été mises en place afin de préparer au mieux le véhicule et l’équipe pour la compétition en septembre 2015

Gluino Decay as a Probe of High Scale Supersymmetry Breaking

A supersymmetric standard model with heavier scalar supersymmetric particles has many attractive features. If the scalar mass scale is O(10 - 10^4) TeV, the standard model like Higgs boson with mass around 125 GeV, which is strongly favored by the LHC experiment, can be realized. However, in this scenario the scalar particles are too heavy to be produced at the LHC. In addition, if the scalar mass is much less than O(10^4) TeV, the lifetime of the gluino is too short to be measured. Therefore, it is hard to probe the scalar particles at a collider. However, a detailed study of the gluino decay reveals that two body decay of the gluino carries important information on the scalar scale. In this paper, we propose a test of this scenario by measuring the decay pattern of the gluino at the LHC.Comment: 29 pages, 9 figures; version published in JHE

Where the Sidewalk Ends: Jets and Missing Energy Search Strategies for the 7 TeV LHC

This work explores the potential reach of the 7 TeV LHC to new colored states in the context of simplified models and addresses the issue of which search regions are necessary to cover an extensive set of event topologies and kinematic regimes. This article demonstrates that if searches are designed to focus on specific regions of phase space, then new physics may be missed if it lies in unexpected corners. Simple multiregion search strategies can be designed to cover all of kinematic possibilities. A set of benchmark models are created that cover the qualitatively different signatures and a benchmark multiregion search strategy is presented that covers these models.Comment: 30 pages, 8 Figures, 3 Tables. Version accepted at JHEP. Minor changes. Added figur

First observation of the KS->pi0 gamma gamma decay

Using the NA48 detector at the CERN SPS, 31 KS->pi0 gamma gamma candidates with an estimated background of 13.7 +- 3.2 events have been observed. This first observation leads to a branching ratio of BR(KS->pi0 gamma gamma) = (4.9 +- 1.6(stat) +- 0.9(syst)) x 10^-8 in agreement with Chiral Perturbation theory predictions.Comment: 10 pages, 4 figures submitted to Phys. Lett.

Search for CP violation in K0 -> 3 pi0 decays

Using data taken during the year 2000 with the NA48 detector at the CERN SPS, a search for the CP violating decay K_S -> 3 pi0 has been performed. From a fit to the lifetime distribution of about 4.9 million reconstructed K0/K0bar -> 3 pi0 decays, the CP violating amplitude eta_000 = A(K_S -> 3 pi0)/A(K_L -> 3 pi0) has been found to be Re(eta_000) = -0.002 +- 0.011 +- 0.015 and Im(eta_000) = -0.003 +- 0.013 +- 0.017. This corresponds to an upper limit on the branching fraction of Br(K_S -> 3 pi0) < 7.4 x 10^-7 at 90% confidence level. The result is used to improve knowledge of Re(epsilon) and the CPT violating quantity Im(delta) via the Bell-Steinberger relation.Comment: 18 pages, 7 figures, submitted to Phys. Lett.

A precision measurement of direct CP violation in the decay of neutral kaons into two pions

The direct CP violation parameter Re(epsilon'/epsilon) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. The 2001 running period was devoted to collecting additional data under varied conditions compared to earlier years (1997-99). The new data yield the result: Re(epsilon'/epsilon) = (13.7 +/- 3.1) times 10^{-4}. Combining this result with that published from the 1997, 98 and 99 data, an overall value of Re(epsilon'/epsilon) = (14.7 +/- 2.2) times 10^{-4} is obtained from the NA48 experiment.Comment: 19 pages, 5 figures, to be published in Physics Letters

Measurement of the Ratio Gamma(KL -> pi+ pi-)/Gamma(KL -> pi e nu) and Extraction of the CP Violation Parameter |eta+-|

We present a measurement of the ratio of the decay rates Gamma(KL -> pi+ pi-)/Gamma(KL -> pi e nu), denoted as Gamma(K2pi)/Gamma(Ke3). The analysis is based on data taken during a dedicated run in 1999 by the NA48 experiment at the CERN SPS. Using a sample of 47000 K2pi and five million Ke3 decays, we find Gamma(K2pi)/Gamma(Ke3) = (4.835 +- 0.022(stat) +- 0.016(syst)) x 10^-3. From this we derive the branching ratio of the CP violating decay KL -> pi+ pi- and the CP violation parameter |eta+-|. Excluding the CP conserving direct photon emission component KL -> pi+ pi- gamma, we obtain the results BR(KL -> pi+ pi-) = (1.941 +- 0.019) x 10^-3 and |eta+-| = (2.223 +- 0.012) x 10^-3.Comment: 20 pages, 7 figures, accepted by Phys. Lett.