Implementation of polarization diversity pulse-pair technique using airborne W-band radar

This work describes the implementation of polarization diversity on the National Research Council Canada W-band Doppler radar and presents the first-ever airborne Doppler measurements derived via polarization diversity pulse-pair processing. The polarization diversity pulse-pair measurements are interleaved with standard pulse-pair measurements with staggered pulse repetition frequency, this allows a better understanding of the strengths and drawbacks of polarization diversity, a methodology that has been recently proposed for wind-focused Doppler radar space missions. Polarization diversity has the clear advantage of making possible Doppler observations of very fast decorrelating media (as expected when deploying Doppler radars on fast-moving satellites) and of widening the Nyquist interval, thus enabling the observation of very high Doppler velocities (up to more than 100 m s−1 in the present work). Crosstalk between the two polarizations, mainly caused by depolarization at backscattering, deteriorated the quality of the observations by introducing ghost echoes in the power signals and by increasing the noise level in the Doppler measurements. In the different cases analyzed during the field campaigns, the regions affected by crosstalk were generally associated with highly depolarized surface returns and depolarization of backscatter from hydrometeors located at short ranges from the aircraft. The variance of the Doppler velocity estimates can be well predicted from theory and were also estimated directly from the observed correlation between the H-polarized and V-polarized successive pulses. The study represents a key milestone towards the implementation of polarization diversity in Doppler space-borne radars

Determination of the muon Yukawa coupling at high energy e+e- linear colliders

The perspectives for the observation of the rare decay H -> mumu decay and the determination of the muon Yukawa coupling at a TeV-class and at a multi-TeV e+e- linear colliders are discussed. The signal for the decay can be obtained at 0.8 TeV and a first estimate of the coupling derived. A linear collider operating at 3 TeV, with high luminosity, is able to improve the accuracy on this couplings to 4% to 11% for 120 GeV < M_H < 150 GeV.Comment: 3 pages, 2 figures, to appear on the proceedings of the Snowmass 2001 Summer Study, Snowmass CO, June-July 200

Light neutralino dark matter in MSSM

Three dark matter direct detection experiments, DAMA, COGENT and CRESST, have reported a possible signal of WIMP interaction corresponding to very light particles, close to the edge of the XENON 100 and CDMS sensitivity. Imposing the latest constraints from colliders, flavour physics, electroweak precision tests and direct and indirect dark matter searches, we show that viable MSSM scenarios with a light neutralino, in agreement with all the present data, are feasible. An analysis of the characteristics of the resulting scenarios will be presented.Comment: 6 pages, 2 figures, contribution to the ICHEP 2012 Conference proceedings, 4-11 July 2012, Melbourne, Australi

Study of e+e- -> H+H- at a 800 GeV Linear Collider

The production and decay of heavy charged Higgs bosons at a 800 GeV e+e- linear collider have been studied. The analysis of the H+H- -> tb tb, expected to be dominant in the MSSM, and H+H- -> W+h0 W-h0 decay modes leading to the same final state consisting of two W bosons and four b quarks, provides with a determination of the boson mass to 1 GeV and of the production cross section with 10% accuracy for 500 fb-1 of data.Comment: 4 pages, 1 figure, to appear in the Proceedings of the 5th Linear Collider Workshop Fermilab, October 200

B2 and G2 Toda systems on compact surfaces: a variational approach

We consider the B2 and G2 Toda systems on compact surfaces. We attack the problem using variational techniques. We get existence and multiplicity of solutions under a topological assumption on the surface and some generic conditions on the parameters. We also extend some of the results to the case of general systems.Comment: 28 pages, accepted on Journal of Mathematical Physic

Implications of LHC Higgs and SUSY searches for MSSM

The implications of the LHC SUSY searches as well as the discovery of a new bosonic state compatible with the lightest Higgs boson will be discussed in the context of constrained and general MSSM scenarios. Exploring the MSSM through the Higgs sector is an alternative and complementary path to direct searches, and tight constraints on the MSSM parameter space can be obtained.Comment: 7 pages, 5 figures, contribution to the ICHEP 2012 Conference proceedings, 4-11 July 2012, Melbourne, Australi

An update of the constraints on the phenomenological MSSM from the new LHC Higgs results

Updated results on the search of Higgs bosons at the LHC with up to 17/fb of data have just been presented by the ATLAS and CMS collaborations. New constraints are provided by the LHCb and XENON experiments with the observation of the rare decay B_s -> mu+mu- and new limits on dark matter direct detection. In this paper, we update and extend the results on the implications of these data on the phenomenological Minimal Supersymmetric extension of the Standard Model (pMSSM) by using high statistics, flat scans of its 19 parameters. The new LHC data on bb and tau tau decays of the lightest Higgs state and the new CMS limits from the tau tau searches for the heavier Higgs states set stronger constraints on the pMSSM parameter space.Comment: 14 pages, 8 figures. This update is based on results presented at HCP 2012 and the December 2012 CERN Council LHC Jamboree. It features larger scan statistics and additional plot

Hybrid Pixel Detector Development for the Linear Collider Vertex Tracker

In order to fully exploit the physics potential of the future high energy e+e- linear collider, a Vertex Tracker able to provide particle track extrapolation with very high resolution is needed. Hybrid Si pixel sensors are an attractive technology due to their fast read-out capabilities and radiation hardness. A novel pixel detector layout with interleaved cells has been developed to improve the single point resolution. Results of the characterisation of the first processed prototypes by electrostatic measurements and charge collection studies are discussed.Comment: 5 pages, 1 figure, to appear in the Proceedings of the 9th Int. Workshop on Vertex Detectors, Lake Michigan MI (USA), September~200