11344422
Benefits of joint LIGO-Virgo coincidence searches for burst and inspiral signals
We examine the benefits of performing a joint LIGO-Virgo search for transient signals. We do this by adding burst and inspiral signals to 24 hours of simulated detector data. We find significant advantages to performing a joint coincidence analysis, above either a LIGO only or Virgo only search. These include an increased detection efficiency, at a fixed false alarm rate, to both burst and inspiral events and an ability to reconstruct the sky location of a signal.
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.
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.
119230543
Pair production of MSSM Higgs bosons in the nondecoupling region at the LHC
We consider the Higgs boson signals from pair production at the LHC within the framework of the MSSM in the non-decoupling (low-m_A) region. In light of the recent observation of a SM-like Higgs boson, we argue that the exploration for Higgs pair production at the LHC is a crucial next step to probe the MSSM Higgs sector. We emphasize that the production of H^\pm A^0 and H^{+}H^{-} depends only on the electroweak gauge couplings while all the leading Higgs production channels via gluon fusion, vector-boson fusion, and Higgsstrahlung depend on additional free Higgs sector parameters. In the non-decoupling region, the five MSSM Higgs bosons are all relatively light and pair production signals may be accessible. We find that at the 8 TeV LHC, a 5\sigma signal for H^\pm A^0, H^\pm h^0 -> \tau^{\pm}\nu b\bar b and H^{+}H^{-} -> \tau^{+}\nu \tau^{-}\nu are achievable with an integrated luminosity of 7 (11) fb^{-1} and 24 (48) fb^{-1}, respectively for m_A=95 (130) GeV. At the 14 TeV LHC, a 5\sigma signal for these two channels would require as little as 4 (7) fb^{-1} and 10 (19) fb^{-1}, respectively.
118711275
New method for the spin determination of dark matter
We construct a new kinematical variable that is able to fully reconstruct the absolute value, and partially reconstruct the sign, of the angular distribution in the center of momentum system of a decaying particle in certain cases where the center of momentum system is only known up to a two-fold ambiguity. After making contact with Drell-Yan production at the Large Hadron Collider, we apply this method to the pair-production of dark matter in association with two charged leptons at the International Linear Collider and show that for a small intermediate width, perfect agreement is found with the true angular distribution in the absence of initial state radiation. In the presence of initial state radiation, we find that the modification to the angular distributions is small for most angles and that the different spin combinations should still be distinguishable. This enables us to determine the spin of the mother particle and the dark matter particle in certain cases.
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.
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.
118726227
Low-energy effective theory, unitarity, and nondecoupling behavior in a model with heavy Higgs-triplet fields
We discuss the properties of a model incorporating both a scalar electroweak Higgs doublet and an electroweak Higgs triplet. We construct the low-energy effective theory for the light Higgs doublet in the limit of small (but nonzero) deviations in the {rho} parameter from one, a limit in which the triplet states become heavy. For {delta}{rho}>0, perturbative unitarity of WW scattering breaks down at a scale inversely proportional to the renormalized vacuum expectation value of the triplet field (or, equivalently, inversely proportional to the square root of {delta}{rho}). This result imposes an upper limit on the mass scale of the heavy triplet bosons in a perturbative theory; we show that this upper bound is consistent with dimensional analysis in the low-energy effective theory. Recent articles have shown that the triplet bosons do not decouple, in the sense that deviations in the {rho} parameter from one do not necessarily vanish at one-loop in the limit of large triplet mass. We clarify that, despite the nondecoupling behavior of the Higgs triplet, this model does not violate the decoupling theorem since it incorporates a large dimensionful coupling. Nonetheless, we show that if the triplet-Higgs boson masses are of order the grand unified theory scale, more » perturbative consistency of the theory requires the (properly renormalized) Higgs-triplet vacuum expectation value to be so small as to be irrelevant for electroweak phenomenology. « less