10,792 research outputs found
Use of cumulants to quantify uncertainties in the HBT measurements of the homogeneity regions
Let us denote p(x|K) the space density of the points where identical
particles of some kind, e.g. pi+ mesons, with momentum K are produced. When
using the HBT method to determine p(x|K) one encounters ambiguities. We show
that these ambiguities do not affect the even cumulants of the distribution
p(x|K). In particular, the HBT radii of the homogeneity regions, which are
given by the second order cumulants, and the distribution of distances between
the pairs of production points for particles with momentum K can be reliably
measured. The odd cumulants are ambiguous. The are, however, correlated. In
particular, when the average position (K) is known as a function of K there
is no further ambiguity.Comment: LateX, 10 pages, no figure
Ambiguities in the HBT approach to determine the interaction regions
The necessary and sufficient condition for a quantity to be measurable by the
HBT method is given and discussed.Comment: Report at the conference QCD08, July 2008, LateX 8 pages, no figure
FairFuzz: Targeting Rare Branches to Rapidly Increase Greybox Fuzz Testing Coverage
In recent years, fuzz testing has proven itself to be one of the most
effective techniques for finding correctness bugs and security vulnerabilities
in practice. One particular fuzz testing tool, American Fuzzy Lop or AFL, has
become popular thanks to its ease-of-use and bug-finding power. However, AFL
remains limited in the depth of program coverage it achieves, in particular
because it does not consider which parts of program inputs should not be
mutated in order to maintain deep program coverage. We propose an approach,
FairFuzz, that helps alleviate this limitation in two key steps. First,
FairFuzz automatically prioritizes inputs exercising rare parts of the program
under test. Second, it automatically adjusts the mutation of inputs so that the
mutated inputs are more likely to exercise these same rare parts of the
program. We conduct evaluation on real-world programs against state-of-the-art
versions of AFL, thoroughly repeating experiments to get good measures of
variability. We find that on certain benchmarks FairFuzz shows significant
coverage increases after 24 hours compared to state-of-the-art versions of AFL,
while on others it achieves high program coverage at a significantly faster
rate
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