119258873
MSSM Higgs bosons at the LHC
Accepting the existence of a SM-like Higgs boson in the range 123GeV-127GeV as indicated by the observed ga,ga events, there are two distinct regions left in the Minimal Supersymmetric (SUSY) Standard Model (MSSM) Higgs sector: (a) the lighter CP-even Higgs boson SM-like and the non-SM-like Higgs bosons all heavy and nearly degenerate above 300GeV; (b) the heavier CP-even Higgs boson being SM-like and the neutral non-SM-like Higgs bosons all nearly degenerate around 100GeV (a non-decoupling region). Due to the strong correlation between the Higgs decays to W+W- and to ga,ga predicted in the MSSM, the deficit of a W+W- final state signal would be in direct conflict with the ga,ga peak. If we consider W+W- on its own, the absence of the W+W- signal would imply that the SM-like Higgs boson has reduced coupling to W+-, and that the other non-SM-like Higgs bosons should not be too heavy and do not decouple. If both the ga,ga excess and the absence of W+W- continue, new physics beyond the MSSM will be required. A similar correlation exists between the W+W- and tau+tau- channels: a reduced W+W- channel would force the tau+tau- channel to be larger. Future searches for the SM-like Higgs boson at the LHC will provide critical tests for the MSSM prediction. We emphasize the potential importance of the electroweak processes pp->H+H-, H+-A0, which are independent of the SUSY parameters except for their masses. In addition, there may be sizable contributions from pp->H+-h0, A0h0 and W+-H0, ZH0 in the non-decoupling region, which may serve to discriminate the model parameters. We vary the relevant SUSY parameters in a broad range and demonstrate the correlations and constraints on these parameters and associated SUSY particles.
16128170
SLHAplus: A library for implementing extensions of the standard model
We provide a library to facilitate the implementation of new models in codes such as matrix element and event generators or codes for computing dark matter observables. The library contains a SLHA reader routine as well as diagonalisation routines. This library is also available in CalcHEP, micrOMEGAs and LanHEP. In the very near future the LHC will have the opportunity to test the TeV scale relevant to address the outstanding issues in the standard model and its extensions: the symmetry breaking problem and the dark matter problem. Furthermore numerous astroparticle searches will help refine the dark matter properties. Confronting the various extensions of the standard model that have been proposed with observations at colliders and astroparticle searches will therefore provide powerful tests of the new physics model. Sophisticated tools have been developed to compute the predictions for observables such as particle spectra, decay rates or cross sections that are relevant at colliders ( for a repository of available tools see [1]) while other tools explore the implications of new physics models for dark matter observables [2, 3, 4, 5, 6]. The interpretation of a new signature might require extending those tools to adapt them to work with different models. Tools such as LanHEP [7], Feynrules [34] and SARAH [9] have been developed to facilitate the implementation of new models in generic matrix elements and event generators such as Madgraph [10], CompHEP [11, 12], CalcHEP [13], FeynArts/FormCalc [14, 15] and Sherpa [16]. They require mainly the implementation of a new Lagrangian and provide the model file adapted to the chosen generator. While these tools are very powerful they often leave some tedious and repetitive tasks for the user. Here we provide a library that contains some routines to facilitate the implementation of new models. The library first contains a routine for reading a SUSY Les Houches Accord (SLHA) file [17, 18]. An SLHA file is a standardized file format specifying input and output parameters that was developed in the framework of supersymmetry to facilitate the passing of information beween codes as varied as spectrum calculators, matrix element generators or event generators. 1 We have generalised the procedure to take into account an arbitrary number of blocks so that the reader can be used in generic models including non supersymmetric ones. The library also contains routines to diagonalise real mass matrices with either unitary or 1 Another SLHA reader library that can be used with the MSSM and its extensions is available at [19].
206997636
CalcHEP 3.4 for collider physics within and beyond the Standard Model
We present version 3.4 of the CalcHEP software package which is designed for effective evaluation and simulation of high energy physics collider processes at parton level. The main features of CalcHEP are the computation of Feynman diagrams, integration over multi-particle phase space and event simulation at parton level. The principle attractive key-points along these lines are that it has: (a) an easy startup and usage even for those who are not familiar with CalcHEP and programming; (b) a friendly and convenient graphical user interface (GUI); (c) the option for the user to easily modify a model or introduce a new model by either using the graphical interface or by using an external package with the possibility of cross checking the results in different gauges; (d) a batch interface which allows to perform very complicated and tedious calculations connecting production and decay modes for processes with many particles in the final state. With this features set, CalcHEP can efficiently perform calculations with a high level of automation from a theory in the form of a Lagrangian down to phenomenology in the form of cross sections, parton level event simulation and various kinematical distributions. In this paper we report on the new features of CalcHEP 3.4 which improves the power of our package to be an effective tool for the study of modern collider phenomenology
51806520
New developments in FEYNRULES
The program FeynRules is a Mathematica package developed to facilitate the implementation of new physics theories into high-energy physics tools. Starting from a minimal set of information such as the model gauge symmetries, its particle content, parameters and Lagrangian, FeynRules provides all necessary routines to extract automatically from the Lagrangian (that can also be computed semi-automatically for supersymmetric theories) the associated Feynman rules. These can be further exported to several Monte Carlo event generators through dedicated interfaces, as well as translated into a Python library, under the so-called UFO model format, agnostic of the model complexity, especially in terms of Lorentz and/or color structures appearing in the vertices or of number of external legs. In this work, we briefly report on the most recent new features that have been added to FeynRules, including full support for spin- 3 fermions, a new module allowing for the automated diagonalization of the particle spectrum and a new set of routines dedicated to decay width calculations.
118577263
Vector Bosons Signals of Electroweak Symmetry Breaking
We study the physics potential of the 8 TeV LHC to discover signals of extended gauge models or extra dimensional models whose low energy behavior is well represented by an SU(2) x SU(2) x U(1) electroweak gauge structure. We find that with a combined integrated luminosity of 40 fb^(-1), the first new Kaluza-Klein mode of the W gauge boson can be discovered up to a mass of about 400 GeV, when produced in association with a Z boson.
119223957
Introducing an interface between WHIZARD and FeynRules
While Monte Carlo event generators like WHIZARD have become indispensable tools in studying the impact of new physics on collider observables over the last decades, the implementation of new models in such packages has remained a rather awkward and error-prone process. Recently, the FeynRules package was introduced which greatly simplifies this process by providing a single unified model format from which model implementations for many different Monte Carlo codes can be derived automatically. In this note, we present an interface which extends FeynRules to provide this functionality also for the WHIZARD package, thus making WHIZARD's strengths and performance easily available to model builders.
10053484
Coherent Bayesian analysis of inspiral signals
In this paper we present a Bayesian parameter estimation method for the analysis of interferometric gravitational wave observations of an inspiral of binary compact objects using data recorded simultaneously by a network of several interferometers at different sites. We consider neutron star or black hole inspirals that are modeled to 3.5 post-Newtonian (PN) order in phase and 2.5 PN in amplitude. Inference is facilitated using Markov chain Monte Carlo (MCMC) methods that are adapted in order to efficiently explore the particular parameter space. Examples are shown to illustrate how and what information about the different parameters can be derived from the data. This study uses simulated signals and data with noise characteristics that are assumed to be defined by the LIGO and Virgo detectors operating at their design sensitivities. Nine parameters are estimated, including those associated with the binary system plus its location on the sky. We explain how this technique will be part of a detection pipeline for binary systems of compact objects with masses up to , including cases where the ratio of the individual masses can be extreme.
122531619
Measuring the stochastic gravitational-radiation background with laser-interferometric antennas.
A study of the method of detecting a stochastic gravitation-wave background (SGWB) with laser-interferometric gravitational-wave antennas is presented. The SGWB can be measured by correlating the output of two or more detectors. The results in this paper can be applied to the planned new generation of kilometer length interferometers, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States, or similar systems in other countries. Advanced detectors will be able to limit the gravity-wave background energy density per logarithmic interval at 100 Hz to 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ times the closure density of the Universe. A survey of potential sources indicates that a pair of antennas will be able to confirm or deny the existence of cosmic strings, or may detect the background produced by extragalactic neutron star binaries. Elements of the optimal interferometer design and orientation for detecting the SGWB, or any gravity wave, are given. In particular, the criteria for orienting a pair of antennas, the trade-off between sensitivity and bandwidth, and the effect of antenna separation on the correlation are presented. A procedure for obtaining the correlated signal from two interferometers is given. The statistical basis of the correlation experiment is presented. The cause and effect of correlated noise is examined. Filtering and data analysis issues are also discussed.
13085972
Using Markov chain Monte Carlo methods for estimating parameters with gravitational radiation data
We present a Bayesian approach to the problem of determining parameters for coalescing binary systems observed with laser interferometric detectors. By applying a Markov Chain Monte Carlo (MCMC) algorithm, specifically the Gibbs sampler, we demonstrate the potential that MCMC techniques may hold for the computation of posterior distributions of parameters of the binary system that created the gravity radiation signal. We describe the use of the Gibbs sampler method, and present examples whereby signals are detected and analyzed from within noisy data.
124645238
Penetration depth measurement of a 6 MeV electron beam in water by magnetic resonance imaging
36860755
Data quality studies for burst analysis of Virgo data acquired during Weekly Science Runs
Virgo started collecting science data during weekends in order to not interfere with commissioning activities. The goal of Weekly Science Runs is to ease the transition between commissioning periods and data taking periods, in addition to providing data sets exploiting the stationary behavior of the detector. The detection of gravitational wave (GW) bursts emitted by core collapse of supernovae is one of the most difficult tasks for the GW community due to the fact that there are uncertainties in the exact shape of the waveforms, as we do not have complete models. A major task for this kind of detection effort is the cleaning of the event triggers found by the detection pipelines, namely the removal of accidental transient signals due to noise source events. In order to clean our data from false GW events, we need to define a strategy for data quality cut and veto of auxiliary and environmental monitoring channels. In this paper we report on the analysis we performed on data acquired during Weekly Science Runs to explore and define the data quality cut and veto studies for burst analysis.