119214149
Testing CP violation in ZZH interactions at the LHC
Abstract We study genuine CP-odd observables at the LHC to test the CP property of the ZZH interaction for a Higgs boson with mass below the threshold to a pair of gauge bosons via the process p p → Z H → l + l − b b ¯ . We illustrate the analysis by including a CP-odd ZZH coupling, and show how to extract the CP asymmetries in the signal events. After selective kinematical cuts to suppress the SM backgrounds plus an optimal log-likelihood analysis, we find that, with a CP violating coupling b ˜ ≃ 0.25 , a CP asymmetry may be established at a 3 σ (5 σ ) level with an integrated luminosity of about 30 (50) fb −1 at the LHC.
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.
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
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.
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.
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.
1028791
Report on the first round of the Mock LISA Data Challenges
The Mock LISA Data Challenges (MLDCs) have the dual purpose of fostering the development of LISA data analysis tools and capabilities, and demonstrating the technical readiness already achieved by the gravitational-wave community in distilling a rich science payoff from the LISA data output. The first round of MLDCs has just been completed: nine challenges consisting of data sets containing simulated gravitational-wave signals produced either by galactic binaries or massive black hole binaries embedded in simulated LISA instrumental noise were released in June 2006 with deadline for submission of results at the beginning of December 2006. Ten groups have participated in this first round of challenges. All of the challenges had at least one entry which successfully characterized the signal to better than 95% when assessed via a correlation with phasing ambiguities accounted for. Here, we describe the challenges, summarize the results and provide a first critical assessment of the entries.
1170383
EXPERIMENTAL EVIDENCE FOR THE ROLE OF CANTORI AS BARRIERS IN A QUANTUM SYSTEM
We investigate the effect of cantori on momentum diffusion in a quantum system. Ultracold caesium atoms are subjected to a specifically designed periodically pulsed standing wave. A cantorus separates two chaotic regions of the classical phase space. Diffusion through the cantorus is classically predicted. Quantum diffusion is only significant when the classical phase-space area escaping through the cantorus per period greatly exceeds Planck's constant. Experimental data and a quantum analysis confirm that the cantori act as barriers.
4996128
Identification of noise artifacts in searches for long-duration gravitational-wave transients
We present an algorithm for the identification of transient noise artifacts (glitches) in cross-correlation searches for long gravitational-wave (GW) transients lasting seconds to weeks. The algorithm utilizes the auto-power in each detector as a discriminator between well-behaved stationary noise (possibly including a GW signal) and non-stationary noise transients. We test thealgorithmwithbothMonteCarlonoiseandtime-shifteddatafromtheLIGO S5 science run and find that it removes a significant fraction of glitches while keeping the vast majority (99.6%) of the data. We show that this cleaned data can be used to observe GW signals at a significantly lower amplitude than can otherwise be achieved. Using an accretion disk instability signal model, we estimate that the algorithm is accidentally triggered at a rate of less than 10 −5 % by realistic signals, and less than 3% even for exceptionally loud signals. We conclude that the algorithm is a safe and effective method for cleaning the cross-correlation data used in searches for long GW transients.
33922336
Search for gravitational waves associated with GRB 050915a using the Virgo detector
In the framework of the expected association between gamma-ray bursts and gravitational waves, we present results of an analysis aimed to search for a burst of gravitational waves in coincidence with gamma-ray burst 050915a. This was a long duration gamma-ray burst detected by Swift during September 2005, when the Virgo gravitational wave detector was engaged in a commissioning run during which the best sensitivity attained in 2005 was exhibited. This offered the opportunity for Virgo's first search for a gravitational wave signal in coincidence with a gamma-ray burst. The result of our study is a set of strain amplitude upper limits, based on the loudest event approach, for different but quite general types of burst signal waveforms. The best upper limit strain amplitudes we obtain are Hz−1/2 around ~200–1500 Hz. These upper limits allow us to evaluate the level up to which Virgo, when reaching nominal sensitivity, will be able to constrain the gravitational wave output associated with a long burst. Moreover, the analysis presented here plays the role of a prototype, crucial in defining a methodology for gamma-ray burst triggered searches with Virgo and opening the way for future joint analyses with LIGO.