Search for SUSY in (Leptons +) Jets + E_T^miss final states

We study the observability of the squarks and gluinos in CMS at LHC. Classical E_T^miss + jets final state as well as a number of additional multilepton signatures (0 leptons, 1 lepton, 2 leptons of the same sign, 2 leptons of the opposite sign and 3 leptons) are investigated . The detection of these sparticles relies on the observation of an excess of events over Standard Model background expectations. The study is made in the framework of a minimal SU(5) mSUGRA model as a function of m_0, m_1/2 for 4 sets of model parameters : tan(beta) = 2 or 35 and sign(mu) = +/- 1 and for fixed value of A_0 = 0. The CMS detector response is modelled using CMSJET 4.51 fast MC code (non-GEANT). The results obtained are presented as 5 sigma detection contours in the m_0, m_1/2 planes and with optimized selection cuts in various regions of the parameter space. The result of these investigations is that with integrated luminosity L=10^5 pb^-1 the squark and gluino mass reach is about 2.5 TeV and covers most of the interesting parts of parameter space according to neutralino relic density expectations. The influence of signal and background cross-section uncertainties on the reach contours is estimated. The effect of pile-up on signal and background is also discussed. This effect is found to be insignificant for E_T^miss and single lepton signatures, whilst only a minor deterioration is seen for multilepton final states.Comment: 28 pages, 28 figure

Upper bound on the density of Ruelle resonances for Anosov flows

Using a semiclassical approach we show that the spectrum of a smooth Anosov vector field V on a compact manifold is discrete (in suitable anisotropic Sobolev spaces) and then we provide an upper bound for the density of eigenvalues of the operator (-i)V, called Ruelle resonances, close to the real axis and for large real parts.Comment: 57 page

Improving the discovery potential of charged Higgs bosons at the Tevatron and Large Hadron Collider

We outline several improvements to the experimental analyses carried out at Tevatron (Run 2) or simulated in view of the Large Hadron Collider (LHC) that could increase the scope of CDF/D0 and ATLAS/CMS in detecting charged Higgs bosonsComment: 6 pages, 4 figures, talk given at the `Seventh Workshop on High Energy Physics Phenomenology WHEPP-VII', Harish Chandra Research Institute, Allahabad, India, 4-15 January 2002 (to be published by PRAMANA - Journal of Physics

Resolvent estimates for normally hyperbolic trapped sets

We give pole free strips and estimates for resolvents of semiclassical operators which, on the level of the classical flow, have normally hyperbolic smooth trapped sets of codimension two in phase space. Such trapped sets are structurally stable and our motivation comes partly from considering the wave equation for Kerr black holes and their perturbations, whose trapped sets have precisely this structure. We give applications including local smoothing effects with epsilon derivative loss for the Schr\"odinger propagator as well as local energy decay results for the wave equation.Comment: Further changes to erratum correcting small problems with Section 3.5 and Lemma 4.1; this now also corrects hypotheses, explicitly requiring trapped set to be symplectic. Erratum follows references in this versio

Selection and reconstruction of the top quarks in the all-hadronic decays at a Linear Collider

A method of reconstruction of the top quarks produced in the process E+E- -> t\bar{t} -> 6 jets at a Linear Collider (LC) is proposed. The approach does not involve a kinematic fit, as well as assumptions on the invariant masses of the dijets originating from the decays of W bosons and, therefore, the method is expected to be less sensitive to theoretical and experimental uncertainties on the top-mass measurement than traditional reconstruction methods. For the first time, the reconstruction of the top quarks was investigated using the full LC detector simulation after taking into account the background arising from QCD multi-jet production.Comment: 22 pages, including 13 figures and 3 table

Forward Jets and Energy Flow in Hadronic Collisions

We observe that at the Large Hadron Collider, using forward + central detectors, it becomes possible for the first time to carry out calorimetric measurements of the transverse energy flow due to "minijets" accompanying production of two jets separated by a large rapidity interval. We present parton-shower calculations of energy flow observables in a high-energy factorized Monte Carlo framework, designed to take into account QCD logarithmic corrections both in the large rapidity interval and in the hard transverse momentum. Considering events with a forward and a central jet, we examine the energy flow in the interjet region and in the region away from the jets. We discuss the role of these observables to analyze multiple parton collision effects.Comment: 9 pages, 5 figures. Version2: added results on azimuthal distributions and more discussion of energy flow definition using jet clusterin

Prospects for Searching for Excited Leptons during RunII of the Fermilab Tevatron

This letter presents a study of prospects of searching for excited leptons during RunII of the Fermilab Tevatron. We concentrate on single and pair production of excited electrons in the photonic decay channel in one CDF/DO detector equivalent for 2 fb^{-1}. By the end of RunIIa, the limits should be easily extended beyond those set by LEP and HERA for excited leptons with mass above about 190 GeV.Comment: 4 pages, 8 figure

Interleaved Parton Showers and Tuning Prospects

General-purpose Monte Carlo event generators have become important tools in particle physics, allowing the simulation of exclusive hadronic final states. In this article we examine the Pythia 8 generator, in particular focusing on its parton-shower algorithms. Some relevant new additions to the code are introduced, that should allow for a better description of data. We also implement and compare with 2 to 3 real-emission QCD matrix elements, to check how well the shower algorithm fills the phase space away from the soft and collinear regions. A tuning of the generator to Tevatron data is performed for two PDF sets and the impact of first new LHC data is examined

Coherent Parton Showers with Local Recoils

We outline a new formalism for dipole-type parton showers which maintain exact energy-momentum conservation at each step of the evolution. Particular emphasis is put on the coherence properties, the level at which recoil effects do enter and the role of transverse momentum generation from initial state radiation. The formulated algorithm is shown to correctly incorporate coherence for soft gluon radiation. Furthermore, it is well suited for easing matching to next-to-leading order calculations.Comment: 24 pages, 3 figure

On QCD analysis of stucture function F2γF_2^{\gamma} in alternative approach

The alternative approach to QCD analysis of the photon structure function $F_2^{\gamma}$ is presented. It differs from the conventional one by the presence of the terms which in conventional approach appear in higher orders. We show that this difference concerns also the photonic parton distribution functions. In the alternative approach, the complete LO analysis of $F_2^{\gamma}$ can be performed as all required quantities are known. At the NLO, however, one of the coefficient function is so far not available and thus only the photonic parton distribution function can be computed and compared to those of standard approach. We discuss the numerical difference of these approaches at the LO and the NLO approximation and show that in case of $F_2^{\gamma}$ this difference is non-negligible and may play an important role in the analysis on photon data of the future experiments.Comment: 25 page