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van Leeuwen M.,National Institute for Subatomic Physics | van Leeuwen M.,University Utrecht
Nuclear and Particle Physics Proceedings | Year: 2016

A study of several observables characterising fragment distributions of medium-modified parton showers using the JEWEL and Q-PYTHIA models is presented, with emphasis on the relation between the different observables. © 2016 Elsevier B.V.

van den Broek T.,Radboud University Nijmegen | van den Broek T.,National Institute for Subatomic Physics | van Suijlekom W.D.,Radboud University Nijmegen
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2011

We derive supersymmetric quantum chromodynamics from a noncommutative spin manifold. We extend the model of Chamseddine and Connes that leads to the Einstein-Yang-Mills action and apply the spectral action principle to derive the Lagrangian of supersymmetric QCD, including soft supersymmetry breaking (negative sign) mass terms for the squarks. We find that these results are in good agreement with the physics literature. © 2011 Elsevier B.V.

Shah S.,Radboud University Nijmegen | Shah S.,National Institute for Subatomic Physics | Nelemans G.,Radboud University Nijmegen | Nelemans G.,National Institute for Subatomic Physics | Nelemans G.,Catholic University of Leuven
Astrophysical Journal | Year: 2014

The space-based gravitational wave (GW) detector, evolved Laser Interferometer Space Antenna (eLISA) is expected to observe millions of compact Galactic binaries that populate our Milky Way. GW measurements obtained from the eLISA detector are in many cases complimentary to possible electromagnetic (EM) data. In our previous papers, we have shown that the EM data can significantly enhance our knowledge of the astrophysically relevant GW parameters of Galactic binaries, such as the amplitude and inclination. This is possible due to the presence of some strong correlations between GW parameters that are measurable by both EM and GW observations, for example, the inclination and sky position. In this paper, we quantify the constraints in the physical parameters of the white-dwarf binaries, i.e., the individual masses, chirp mass, and the distance to the source that can be obtained by combining the full set of EM measurements such as the inclination, radial velocities, distances, and/or individual masses with the GW measurements. We find the following 2σ fractional uncertainties in the parameters of interest. The EM observations of distance constrain the chirp mass to ∼15%-25%, whereas EM data of a single-lined spectroscopic binary constrain the secondary mass and the distance with factors of two to ∼40%. The single-line spectroscopic data complemented with distance constrains the secondary mass to ∼25%-30%. Finally, EM data on double-lined spectroscopic binary constrain the distance to ∼30%. All of these constraints depend on the inclination and the signal strength of the binary systems. We also find that the EM information on distance and/or the radial velocity are the most useful in improving the estimate of the secondary mass, inclination, and/or distance. © 2014. The American Astronomical Society. All rights reserved.

Del Pozzo W.,National Institute for Subatomic Physics
Journal of Physics: Conference Series | Year: 2014

Second-generation ground-based laser interferometers are expected to deliver a wealth of gravitational waves (GW) events from coalescing compact binaries up to a redshift of about 0.3. Being free of the systematics affecting electromagnetic measurements, GW offer the possibility of an independent measurement of H0. This paper presents a method based on Bayesian inference aimed at estimating the value of the cosmological parameters for any GW event. In contrast to earlier work, this framework does not require the precise identification of the putative optical counterpart, but it considers all the potential galaxy hosts consistent with the recovered sky position and distance posterior distributions. When applied to the upcoming network of second generation interferometers, 50 GW events will yield a measurement of H 0 with an uncertainty of a few per cents. © Published under licence by IOP Publishing Ltd.

Kuijer P.G.,National Institute for Subatomic Physics
EPJ Web of Conferences | Year: 2012

The LHC results on particle and transverse energy production and Bose-Einstein correlations show that the system produced in Pb-Pb collisions at √sNN = 2.76TeV is significantly larger, lives longer and is hotter and denser than at RHIC energies. The particle spectra and soft particle correlations allow a more detailed study of the properties of the produced system and its initial conditions. This contribution highlights some of the first soft physics results from the LHC. © Owned by the authors 2012.

Del Pozzo W.,National Institute for Subatomic Physics | Del Pozzo W.,University of Birmingham
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

The advanced worldwide network of gravitational waves (GW) observatories is scheduled to begin operations within the current decade. Thanks to their improved sensitivity, they promise to yield a number of detections and thus to open new observational windows for astronomy and astrophysics. Among the scientific goals that should be achieved, there is the independent measurement of the value of the cosmological parameters, hence an independent test of the current cosmological paradigm. Because of the importance of such a task, a number of studies have evaluated the capabilities of GW telescopes in this respect. However, since GW do not yield information about the source redshift, different groups have made different assumptions regarding the means through which the GW redshift can be obtained. These different assumptions imply also different methodologies to solve this inference problem. This work presents a formalism based on Bayesian inference developed to facilitate the inclusion of all assumptions and prior information about a GW source within a single data analysis framework. This approach guarantees the minimization of information loss and the possibility of including naturally event-specific knowledge (such as the sky position for a gamma ray burst-GW coincident observation) in the analysis. The workings of the method are applied to a specific example, loosely designed along the lines of the method proposed by Schutz in 1986, in which one uses information from wide-field galaxy surveys as prior information for the location of a GW source. I show that combining the results from few tens of observations from a network of advanced interferometers will constrain the Hubble constant H 0 to an accuracy of ∼4%-5% at 95% confidence. © 2012 American Physical Society.

Van Den Broeck C.,National Institute for Subatomic Physics | Van Den Broeck C.,University of Cardiff | Trias M.,University of the Balearic Islands | Sathyaprakash B.S.,University of Cardiff | Sintes A.M.,University of the Balearic Islands
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

The Laser Interferometer Space Antenna's (LISA's) observation of supermassive binary black holes (SMBBH) could provide a new tool for precision cosmography. Inclusion of subdominant signal harmonics in the inspiral signal allows for high-accuracy sky localization, dramatically improving the chances of finding the host galaxy and obtaining its redshift. A SMBBH merger can potentially have component masses from a wide range (105-108M) over which parameter accuracies vary considerably. We perform an in-depth study in order to understand (i) what fraction of possible SMBBH mergers allow for sky localization, depending on the parameters of the source, and (ii) how accurately w can be measured when the host galaxy can be identified. We also investigate how accuracies on all parameters improve when a knowledge of the sky position can be folded into the estimation of errors. We find that w can be measured to within a few percent in most cases, if the only error in measuring the luminosity distance is due to LISA's instrumental noise and the confusion background from Galactic binaries. However, weak lensing-induced errors will severely degrade the accuracy with which w can be obtained, emphasizing that methods to mitigate weak lensing effects would be required to take advantage of LISA's full potential. © 2010 The American Physical Society.

van den Broek T.,Radboud University Nijmegen | van den Broek T.,National Institute for Subatomic Physics | van Suijlekom W.D.,Radboud University Nijmegen
Communications in Mathematical Physics | Year: 2011

We derive supersymmetric quantum chromodynamics from a noncommutative manifold, using the spectral action principle of Chamseddine and Connes. After a review of the Einstein-Yang-Mills system in noncommutative geometry, we establish in full detail that it possesses supersymmetry. This noncommutative model is then extended to give a theory of quarks, squarks, gluons and gluinos by constructing a suitable noncommutative spin manifold (i. e. a spectral triple). The particles are found at their natural place in a spectral triple: the quarks and gluinos as fermions in the Hilbert space, the gluons and squarks as the (bosonic) inner fluctuations of a (generalized) Dirac operator by the algebra of matrix-valued functions on a manifold. The spectral action principle applied to this spectral triple gives the Lagrangian of supersymmetric QCD, including supersymmetry breaking (negative) mass terms for the squarks. We find that these results are in good agreement with the physics literature. © 2011 The Author(s).

Sathyaprakash B.S.,University of Cardiff | Schutz B.F.,Max Planck Institute for Physics | Van Den Broeck C.,National Institute for Subatomic Physics
Classical and Quantum Gravity | Year: 2010

The Einstein Telescope, a third-generation gravitational-wave detector under a design study, could detect millions of binary neutron star inspirals each year. A small fraction of these events might be observed as gamma-ray bursts, helping to measure both the luminosity distance DL to and redshift z of the source. By fitting these measured values of DL and z to a cosmological model, it would be possible to infer the dark energy equation of state to within 1.5% without the need to correct for errors in DL caused by weak lensing. This compares favourably with 0.3-10% accuracy that can be achieved with the Laser Interferometer Space Antenna (where weak lensing will need to be dealt with) as well as with dedicated dark energy missions that have been proposed, where 3.5-11% uncertainty is expected. © 2010 IOP Publishing Ltd.

Farinelli C.,National Institute for Subatomic Physics
IEEE Nuclear Science Symposium Conference Record | Year: 2012

The LHCb experiment at the Large Hadron Collider (LHC) at CERN is a dedicated experiment designed to search for New Physics in the decays of beauty and charm hadrons. These hadrons are identified via their flight distance in the Vertex Locator (VELO), making the VELO extremely important for the physics performance of LHCb. The VELO is a silicon strip detector, located around the interaction region. It consists of two retractable halves with 21 modules each, which are open during injection and closed when 'stable beams' are declared, bringing the VELO sensors at a distance of 8 mm from the LHC beams. Each module has two n-on-n type silicon sensors mounted back to back. Due to its proximity to the beam it is subject to high doses of radiation, which are non-uniform across the sensors and along the z-axis. The VELO has been operated successfully during the first two years of data taking. Results for the hit resolution, primary vertex resolution and impact parameter resolution are presented. Some aspects of radiation damage are also discussed. © 2012 IEEE.

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