15385740
A comprehensive approach to new physics simulations
We describe a framework to develop, implement and validate any perturbative Lagrangian-based particle physics model for further theoretical, phenomenological and experimental studies. The starting point is FeynRules, a Mathematica package that allows to generate Feynman rules for any Lagrangian and then, through dedicated interfaces, automatically pass the corresponding relevant information to any supported Monte Carlo event generator. We prove the power, robustness and flexibility of this approach by presenting a few examples of new physics models (the Hidden Abelian Higgs Model, the general Two-Higgs-Doublet Model, the most general Minimal Supersymmetric Standard Model, the Minimal Higgsless Model, Universal and Large Extra Dimensions, and QCD-inspired effective Lagrangians) and their implementation/validation in FeynArts/FormCalc, CalcHep, MadGraph/MadEvent, and Sherpa.
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.
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
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].
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.
32344440
Parameter estimation of spinning binary inspirals using Markov-chain Monte Carlo
We present a Markov chain Monte Carlo (MCMC) technique to study the source parameters of gravitational-wave signals from the inspirals of stellar-mass compact binaries detected with ground-based gravitational-wave detectors such as LIGO and Virgo, for the case where spin is present in the more massive compact object in the binary. We discuss the aspects of the MCMC algorithm that allow us to sample the parameter space in an efficient way. We show sample runs that illustrate the possibilities of our MCMC code and the difficulties that we encounter.
28345902
Bayesian modeling of source confusion in LISA data
One of the greatest data analysis challenges for the Laser Interferometer Space Antenna (LISA) is the need to account for a large number of gravitational wave signals from compact binary systems expected to be present in the data. We introduce the basis of a Bayesian method that we believe can address this challenge and demonstrate its effectiveness on a simplified problem involving 100 synthetic sinusoidal signals in noise. We use a reversible jump Markov chain Monte Carlo technique to infer simultaneously the number of signals present, the parameters of each identified signal, and the noise level. Our approach therefore tackles the detection and parameter estimation problems simultaneously, without the need to evaluate formal model selection criteria, such as the Akaike Information Criterion or explicit Bayes factors. The method does not require a stopping criterion to determine the number of signals and produces results which compare very favorably with classical spectral techniques.
119332495
Interferometric gravitational wave detection at MIT
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.
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.