6,458 research outputs found
TauSpinner program for studies on spin effect in tau production at the LHC
Final states involving tau leptons are important components of searches for
new particles at the Large Hadron Collider (LHC). A proper treatment of tau
spin effects in the Monte Carlo (MC) simulations is important for understanding
the detector acceptance as well as for the measurements of tau polarization and
tau spin correlations. In this note we present a TauSpinner package designed to
simulate the spin effects. It relies on the availability of the four-momenta of
the taus and their decay products in the analyzed data. The flavor and the
four-momentum of the boson decaying to the tau-tau+ or tau+- nu pair need to be
known. In the Z/gamma* case the initial state quark configuration is attributed
from the intermediate boson kinematics, and the parton distribution functions
(PDF's). TauSpinner is the first algorithm suitable for emulation of tau spin
effects in tau-embedded samples. It is also the first tool that offers the user
the flexibility to simulate a desired spin effect at the analysis level. An
algorithm to attribute tau helicity states to a previously generated sample is
also provided.Comment: 13 pages, 6 figures New feature, an algorithm to attribute tau
helicity states introduced in v
Bayesian computational methods
In this chapter, we will first present the most standard computational
challenges met in Bayesian Statistics, focussing primarily on mixture
estimation and on model choice issues, and then relate these problems with
computational solutions. Of course, this chapter is only a terse introduction
to the problems and solutions related to Bayesian computations. For more
complete references, see Robert and Casella (2004, 2009), or Marin and Robert
(2007), among others. We also restrain from providing an introduction to
Bayesian Statistics per se and for comprehensive coverage, address the reader
to Robert (2007), (again) among others.Comment: This is a revised version of a chapter written for the Handbook of
Computational Statistics, edited by J. Gentle, W. Hardle and Y. Mori in 2003,
in preparation for the second editio
Test Set Diameter: Quantifying the Diversity of Sets of Test Cases
A common and natural intuition among software testers is that test cases need
to differ if a software system is to be tested properly and its quality
ensured. Consequently, much research has gone into formulating distance
measures for how test cases, their inputs and/or their outputs differ. However,
common to these proposals is that they are data type specific and/or calculate
the diversity only between pairs of test inputs, traces or outputs.
We propose a new metric to measure the diversity of sets of tests: the test
set diameter (TSDm). It extends our earlier, pairwise test diversity metrics
based on recent advances in information theory regarding the calculation of the
normalized compression distance (NCD) for multisets. An advantage is that TSDm
can be applied regardless of data type and on any test-related information, not
only the test inputs. A downside is the increased computational time compared
to competing approaches.
Our experiments on four different systems show that the test set diameter can
help select test sets with higher structural and fault coverage than random
selection even when only applied to test inputs. This can enable early test
design and selection, prior to even having a software system to test, and
complement other types of test automation and analysis. We argue that this
quantification of test set diversity creates a number of opportunities to
better understand software quality and provides practical ways to increase it.Comment: In submissio
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