14640351
A Bayesian method to set upper limits on the strength of a periodic gravitational wave signal from the remnant of SN1987A: possible applications in LIGO searches
We present a method that assesses the theoretical detection limit of a Bayesian Markov chain Monte Carlo search for a periodic gravitational wave signal emitted by a neutron star. Inverse probability yields an upper limit estimate for the strength when a signal could not be detected in an observed data set. The proposed method is based on Bayesian model comparison that automatically quantifies Occam s Razor. It limits the complexity of a model by favoring the most parsimonious model that explains the data. By comparing the model with a signal from a pulsar to the null model that assumes solely noise, we derive the detection probability and an estimate for the upper limit that a search, for example, for a narrow-band emission for SN1987a, might yield on data at the sensitivity of LIGO data for an observation time of one year.
15022161
A first comparison of search methods for gravitational wave bursts using LIGO and Virgo simulated data
We present a comparative study of six search methods for gravitational wave bursts using simulated LIGO and Virgo noise data. The simulated data were generated according to the design sensitivity of the two 4 km LIGO interferometers and the 3 km Virgo interferometer. The searches were applied on replicas of the data sets to which eight different signals were injected. Three figures of merit were employed in this analysis: (a) receiver operator characteristic curves, (b) necessary signal-to-noise ratios for the searches to achieve 50% and 90% efficiencies and (c) variance and bias for the estimation of the arrival time of a gravitational wave burst.
122598875
RESULTS FROM LIGO OBSERVATIONS: STOCHASTIC BACKGROUND AND CONTINUOUS WAVE SIGNALS
The search for gravitational radiation has entered a new era as the Laser Interferom-eter Gravitational Wave Observatory (LIGO) has reached its initial target sensitivity. Other similar interferometric detectors are also approaching their design goals. There is presently vigorous activity in the gravitational radiation community in the search for signals. Here we review the status of the LIGO search for a stochastic background, and continuous wave signals.
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.
43905547
Veto studies for LIGO inspiral triggers
LIGO recently conducted its third scientific data run, S3. Here, we summarize the veto and data quality studies conducted by the LIGO Scientific Collaboration in connection with the search for binary inspiral signals in the S3 data. The veto results presented here come from studies on the S3 playground data. LIGO's interferometer channels and physical environmental monitors were monitored, and events in these channels coincident with inspiral triggers were examined.
2702261
LISA source confusion: identification and characterization of signals
The Laser Interferometer Space Antenna (LISA) is expected to detect gravitational radiation from a large number of compact binary systems. We present a method by which these signals can be identified and have their parameters estimated. Our approach uses Bayesian inference, specifically the application of a Markov chain Monte Carlo method. The simulation study that we present here considers a large number of sinusoidal signals in noise, and our method estimates the number of periodic signals present in the data, the parameters for these signals and the noise level. The method is significantly better than classical spectral techniques at performing these tasks and does not use stopping criteria for estimating the number of signals present.
53470475
Implications of dynamical generation of standard-model fermion masses
We point out that if quark and lepton masses arise dynamically, then in a wide class of theories the corresponding running masses m{sub f{sub j}}(p) exhibit the power-law decay m{sub f{sub j}}(p){proportional_to}{lambda}{sub j}{sup 2}/p{sup 2} for Euclidean momenta p>>{lambda}{sub j}, where f{sub j} is a fermion of generation j, and {lambda}{sub j} is the maximal scale relevant for the origin of m{sub f{sub j}}. We estimate resultant changes in precision electroweak quantities and compare with current data. It is found that these data allow the presence of such corrections. We also note that this power-law decay renders primitively divergent fermion mass corrections finite.
119276517
On Tree-Level Unitarity in Theories of Massive Spin-2 Bosons
We analyze the tree-level 2->2 scattering of massive spin-2 bosons in a theory with only relevant and marginal operators and extract the sum rules on the coupling constants and masses required to achieve tree-level unitarity to very high energy. We do this for four illustrative cases. In the first, we include massive spin-1 and spin-0 bosons in our theory, but do not require gauge invariance. For this case, we find that it is, in fact, possible to construct a theory where all 2->2 scattering processes are tree-level unitary to very high energy. In the second case, we consider a theory that only includes massive spin-2 and spin-0 bosons. In the absence of spin-1 bosons, we find that it is impossible to unitarize the spin-2 scattering. In the third and fourth cases, we reintroduce the spin-1 bosons as gauge bosons and demand that all interactions are gauge invariant. We take the spin-2 bosons to transform under the adjoint representation of one or two gauge groups. For both of these cases, we find that unitarization is unachievable.
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.
119300724
The Top Triangle Moose
We introduce a deconstructed model that incorporates both Higgsless and top-color mechanisms. The model alleviates the typical tension in Higgsless models between obtaining the correct top quark mass and keeping delta-rho small. It does so by singling out the top quark mass generation as arising from a Yukawa coupling to an effective top-Higgs which develops a small vacuum expectation value, while electroweak symmetry breaking results largely from a Higgsless mechanism. As a result, the heavy partners of the SM fermions can be light enough to be seen at the LHC.
12180176
FeynRules - Feynman rules made easy
In this paper we present FeynRules, a new Mathematica package that facilitates the implementation of new particle physics models. After the user implements the basic model information (e.g. particle content, parameters and Lagrangian), FeynRules derives the Feynman rules and stores them in a generic form suitable for translation to any Feynman diagram calculation program. The model can then be translated to the format specific to a particular Feynman diagram calculator via FeynRules translation interfaces. Such interfaces have been written for CalcHEP/CompHEP, FeynArts/FormCalc, MadGraph/MadEvent and Sherpa, making it possible to write a new model once and have it work in all of these programs. In this paper, we describe how to implement a new model, generate the Feynman rules, use a generic translation interface, and write a new translation interface. We also discuss the details of the FeynRules code. Comment: 63 pages, 3 figures, 17 tables, elsart