31,456 research outputs found
Cumulative particle production as a rare event
The generalization of the Glauber formula for cumulative production events is
derived. On its basis the multiplicity distribution in such events is related
to the one in the minimum bias events. As compared to the rare events of type
, the formula involves a shift in the arguments determined by the
multiplicity from a collision with a cluster of several nucleons.Comment: 11 pages, LaTe
Fusion of strings vs. percolation and the transition to the quark-gluon plasma
In most of the models of hadronic collisions the number of exchanged colour
strings grows with energy and atomic numbers of the projectile and target. At
high string densities interaction between them should melt them into the
quark-gluon plasma state. It is shown that under certain assumptions about the
the string interaction, a phase transition to the quark gluon plasma indeed
takes place in the system of many colour strings. It may be of the first or
second order (percolation), depending on the particular mechanism of the
interaction. The critical string density is about unity in both cases. The
critical density may have been already reached in central Pb-Pb collisions at
158 A GeV.Comment: 16 pages, 3 Postscript figure
Equation of state of non-relativistic matter from automated perturbation theory and complex Langevin
We calculate the pressure and density of polarized non-relativistic systems
of two-component fermions coupled via a contact interaction at finite
temperature. For the unpolarized one-dimensional system with an attractive
interaction, we perform a third-order lattice perturbation theory calculation
and assess its convergence by comparing with hybrid Monte Carlo. In that
regime, we also demonstrate agreement with real Langevin. For the repulsive
unpolarized one-dimensional system, where there is a so-called complex phase
problem, we present lattice perturbation theory as well as complex Langevin
calculations. For our studies, we employ a Hubbard-Stratonovich transformation
to decouple the interaction and automate the application of Wick's theorem for
perturbative calculations, which generates the diagrammatic expansion at any
order. We find excellent agreement between the results from our perturbative
calculations and stochastic studies in the weakly interacting regime. In
addition, we show predictions for the strong coupling regime as well as for the
polarized one-dimensional system. Finally, we show a first estimate for the
equation of state in three dimensions where we focus on the polarized unitary
Fermi gas.Comment: 8 pages, 6 figures, proceedings of Lattice2017, Granada, Spai
Thermal equation of state of polarized fermions in one dimension via complex chemical potentials
We present a nonperturbative computation of the equation of state of
polarized, attractively interacting, nonrelativistic fermions in one spatial
dimension at finite temperature. We show results for the density, spin
magnetization, magnetic susceptibility, and Tan's contact. We compare with the
second-order virial expansion, a next-to-leading-order lattice perturbation
theory calculation, and interpret our results in terms of pairing correlations.
Our lattice Monte Carlo calculations implement an imaginary chemical potential
difference to avoid the sign problem. The thermodynamic results on the
imaginary side are analytically continued to obtain results on the real axis.
We focus on an intermediate- to strong-coupling regime, and cover a wide range
of temperatures and spin imbalances.Comment: 14 pages, 19 figures; published versio
Production of Strange Clusters and Strange Matter in Nucleus-Nucleus Collisions at the AGS
Production probabilities for strange clusters and strange matter in Au+Au
collisions at AGS energy are obtained in the thermal fireball model. The only
parameters of the model, the baryon chemical potential and temperature, were
determined from a description of the rather complete set of hadron yields from
Si+nucleus collisions at the AGS. For the production of light nuclear fragments
and strange clusters the results are similar to recent coalescence model
calculations. Strange matter production with baryon number larger than 10 is
predicted to be much smaller than any current experimental sensitivities.Comment: 9 Pages (no figures
QSO Absorption Line Constraints on Intragroup High-Velocity Clouds
We show that the number statistics of moderate redshift MgII and Lyman limit
absorbers may rule out the hypothesis that high velocity clouds are infalling
intragroup material.Comment: 4 pages, no figures; submitted to Astrophysical Journal Letters;
revised version, more general and includes more about Braun and Burton CHVC
On the relation between Differential Privacy and Quantitative Information Flow
Differential privacy is a notion that has emerged in the community of
statistical databases, as a response to the problem of protecting the privacy
of the database's participants when performing statistical queries. The idea is
that a randomized query satisfies differential privacy if the likelihood of
obtaining a certain answer for a database is not too different from the
likelihood of obtaining the same answer on adjacent databases, i.e. databases
which differ from for only one individual. Information flow is an area of
Security concerned with the problem of controlling the leakage of confidential
information in programs and protocols. Nowadays, one of the most established
approaches to quantify and to reason about leakage is based on the R\'enyi min
entropy version of information theory. In this paper, we analyze critically the
notion of differential privacy in light of the conceptual framework provided by
the R\'enyi min information theory. We show that there is a close relation
between differential privacy and leakage, due to the graph symmetries induced
by the adjacency relation. Furthermore, we consider the utility of the
randomized answer, which measures its expected degree of accuracy. We focus on
certain kinds of utility functions called "binary", which have a close
correspondence with the R\'enyi min mutual information. Again, it turns out
that there can be a tight correspondence between differential privacy and
utility, depending on the symmetries induced by the adjacency relation and by
the query. Depending on these symmetries we can also build an optimal-utility
randomization mechanism while preserving the required level of differential
privacy. Our main contribution is a study of the kind of structures that can be
induced by the adjacency relation and the query, and how to use them to derive
bounds on the leakage and achieve the optimal utility
The dryout region in frictionally heated sliding contacts
Some conditions under which boiling and two-phase flow can occur in or near a wet sliding contact are determined and illustrated. The experimental apparatus consisted of a tool pressed against an instrumented slider plate and motion picture sequences at 4000 frames/sec. The temperature and photographic data demonstrated surface conditions of boiling, drying, trapped gas evolution (solutions), and volatility of fluid mixture components. The theoretical modeling and analysis are in reasonable agreement with experimental data
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