2,697 research outputs found
Study of soft QCD at the Tevatron
Measurements of particle production and inclusive differential crosssections in inelastic pp collisions are reported together with studies of the underlying event in various event topologies. A comparison with Monte Carlo model predictions at the hadron level is performed. The aim is to provide data that can be used to improve QCD models of minimum-bias production and of the underlying event
Algebras for parameterised monads
Parameterised monads have the same relationship to adjunctions with parameters as monads do to adjunctions. In this paper, we investigate algebras for parameterised monads. We identify the Eilenberg-Moore category of algebras for parameterised monads and prove a generalisation of Beck’s theorem characterising this category. We demonstrate an application of this theory to the semantics of type and effect systems
Layer by layer - Combining Monads
We develop a method to incrementally construct programming languages. Our
approach is categorical: each layer of the language is described as a monad.
Our method either (i) concretely builds a distributive law between two monads,
i.e. layers of the language, which then provides a monad structure to the
composition of layers, or (ii) identifies precisely the algebraic obstacles to
the existence of a distributive law and gives a best approximant language. The
running example will involve three layers: a basic imperative language enriched
first by adding non-determinism and then probabilistic choice. The first
extension works seamlessly, but the second encounters an obstacle, which
results in a best approximant language structurally very similar to the
probabilistic network specification language ProbNetKAT
Hilbert-Post completeness for the state and the exception effects
In this paper, we present a novel framework for studying the syntactic
completeness of computational effects and we apply it to the exception effect.
When applied to the states effect, our framework can be seen as a
generalization of Pretnar's work on this subject. We first introduce a relative
notion of Hilbert-Post completeness, well-suited to the composition of effects.
Then we prove that the exception effect is relatively Hilbert-Post complete, as
well as the "core" language which may be used for implementing it; these proofs
have been formalized and checked with the proof assistant Coq.Comment: Siegfried Rump (Hamburg University of Technology), Chee Yap (Courant
Institute, NYU). Sixth International Conference on Mathematical Aspects of
Computer and Information Sciences , Nov 2015, Berlin, Germany. 2015, LNC
Generic Fibrational Induction
This paper provides an induction rule that can be used to prove properties of
data structures whose types are inductive, i.e., are carriers of initial
algebras of functors. Our results are semantic in nature and are inspired by
Hermida and Jacobs' elegant algebraic formulation of induction for polynomial
data types. Our contribution is to derive, under slightly different
assumptions, a sound induction rule that is generic over all inductive types,
polynomial or not. Our induction rule is generic over the kinds of properties
to be proved as well: like Hermida and Jacobs, we work in a general fibrational
setting and so can accommodate very general notions of properties on inductive
types rather than just those of a particular syntactic form. We establish the
soundness of our generic induction rule by reducing induction to iteration. We
then show how our generic induction rule can be instantiated to give induction
rules for the data types of rose trees, finite hereditary sets, and
hyperfunctions. The first of these lies outside the scope of Hermida and
Jacobs' work because it is not polynomial, and as far as we are aware, no
induction rules have been known to exist for the second and third in a general
fibrational framework. Our instantiation for hyperfunctions underscores the
value of working in the general fibrational setting since this data type cannot
be interpreted as a set.Comment: For Special Issue from CSL 201
A semantical approach to equilibria and rationality
Game theoretic equilibria are mathematical expressions of rationality.
Rational agents are used to model not only humans and their software
representatives, but also organisms, populations, species and genes,
interacting with each other and with the environment. Rational behaviors are
achieved not only through conscious reasoning, but also through spontaneous
stabilization at equilibrium points.
Formal theories of rationality are usually guided by informal intuitions,
which are acquired by observing some concrete economic, biological, or network
processes. Treating such processes as instances of computation, we reconstruct
and refine some basic notions of equilibrium and rationality from the some
basic structures of computation.
It is, of course, well known that equilibria arise as fixed points; the point
is that semantics of computation of fixed points seems to be providing novel
methods, algebraic and coalgebraic, for reasoning about them.Comment: 18 pages; Proceedings of CALCO 200
Effect of hard processes on momentum correlations in and collisions
The HBT radii extracted in p-pbar and pp collisions at SPS and Tevatron show
a clear correlation with the charged particle rapidity density. We propose to
explain the correlation using a simple model where the distance from the
initial hard parton-parton scattering to the hadronization point depends on the
energy of the partons emitted. Since the particle multiplicity is correlated
with the mean energy of the partons produced we can explain the experimental
observations without invoking scenarios that assume a thermal fireball. The
model has been applied with success to the existing experimental data both in
the magnitude and the intensity of the correlation. As well, the model has been
extended to pp collisions at the LHC energy of 14 TeV. The possibilities of a
better insight into the string spatial development using 3D HBT analysis is
discussed.Comment: 12 pages, 6 figure
Dual-readout Calorimetry
The RD52 Project at CERN is a pure instrumentation experiment whose goal is
to understand the fundamental limitations to hadronic energy resolution, and
other aspects of energy measurement, in high energy calorimeters. We have found
that dual-readout calorimetry provides heretofore unprecedented information
event-by-event for energy resolution, linearity of response, ease and
robustness of calibration, fidelity of data, and particle identification,
including energy lost to binding energy in nuclear break-up. We believe that
hadronic energy resolutions of {\sigma}/E 1 - 2% are within reach for
dual-readout calorimeters, enabling for the first time comparable measurement
preci- sions on electrons, photons, muons, and quarks (jets). We briefly
describe our current progress and near-term future plans. Complete information
on all aspects of our work is available at the RD52 website
http://highenergy.phys.ttu.edu/dream/.Comment: 10 pages, 10 figures, Snowmass White pape
Charged-Particle Multiplicity in Proton-Proton Collisions
This article summarizes and critically reviews measurements of
charged-particle multiplicity distributions and pseudorapidity densities in
p+p(pbar) collisions between sqrt(s) = 23.6 GeV and sqrt(s) = 1.8 TeV. Related
theoretical concepts are briefly introduced. Moments of multiplicity
distributions are presented as a function of sqrt(s). Feynman scaling, KNO
scaling, as well as the description of multiplicity distributions with a single
negative binomial distribution and with combinations of two or more negative
binomial distributions are discussed. Moreover, similarities between the energy
dependence of charged-particle multiplicities in p+p(pbar) and e+e- collisions
are studied. Finally, various predictions for pseudorapidity densities, average
multiplicities in full phase space, and multiplicity distributions of charged
particles in p+p(pbar) collisions at the LHC energies of sqrt(s) = 7 TeV, 10
TeV, and 14 TeV are summarized and compared.Comment: Invited review for Journal of Physics G -- version 2: version after
referee's comment
Extended Call-by-Push-Value: Reasoning About Effectful Programs and Evaluation Order
Traditionally, reasoning about programs under varying evaluation regimes (call-by-value, call-by-name etc.) was done at the meta-level, treating them as term rewriting systems. Levy’s call-by-push-value (CBPV) calculus provides a more powerful approach for reasoning, by treating CBPV terms as a common intermediate language which captures both call-by-value and call-by-name, and by allowing equational reasoning about changes to evaluation order between or within programs.
We extend CBPV to additionally deal with call-by-need, which is non-trivial because of shared reductions. This allows the equational reasoning to also support call-by-need. As an example, we then prove that call-by-need and call-by-name are equivalent if nontermination is the only side-effect in the source language.
We then show how to incorporate an effect system. This enables us to exploit static knowledge of the potential effects of a given expression to augment equational reasoning; thus a program fragment might be invariant under change of evaluation regime only because of knowledge of its effects
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