46,156 research outputs found
Balls-in-boxes duality for coalescing random walks and coalescing Brownian motions
We present a duality relation between two systems of coalescing random walks
and an analogous duality relation between two systems of coalescing Brownian
motions. Our results extends previous work in the literature and we apply it to
the study of a system of coalescing Brownian motions with Poisson immigration.Comment: 13 page
Coalescing at 8 GeV in the Fermilab Main Injector
For Project X, it is planned to inject a beam of 3 10**11 particles per bunch
into the Main Injector. To prepare for this by studying the effects of higher
intensity bunches in the Main Injector it is necessary to perform coalescing at
8 GeV. The results of a series of experiments and simulations of 8 GeV
coalescing are presented. To increase the coalescing efficiency adiabatic
reduction of the 53 MHz RF is required, resulting in ~70% coalescing efficiency
of 5 initial bunches. Data using wall current monitors has been taken to
compare previous work and new simulations for 53 MHz RF reduction, bunch
rotations and coalescing, good agreement between experiment and simulation was
found. Possible schemes to increase the coalescing efficiency and generate even
higher intensity bunches are discussed. These require improving the timing
resolution of the low level RF and/or tuning the adiabatic voltage reduction of
the 53 MHz.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012)
20-25 May 2012, New Orleans, Louisian
A superprocess involving both branching and coalescing
We consider a superprocess with coalescing Brownian spatial motion. We first
prove a dual relationship between two systems of coalescing Brownian motions.
In consequence we can express the Laplace functionals for the superprocess in
terms of coalescing Brownian motions, which allows us to obtain some explicit
results. We also point out several connections between such a superprocess and
the Arratia flow. A more general model is discussed at the end of this paper.Comment: 25 page
Coalescing Brownian flows: A new approach
The coalescing Brownian flow on is a process which was
introduced by Arratia [Coalescing Brownian motions on the line (1979) Univ.
Wisconsin, Madison] and T\'{o}th and Werner [Probab. Theory Related Fields 111
(1998) 375-452], and which formally corresponds to starting coalescing Brownian
motions from every space-time point. We provide a new state space and topology
for this process and obtain an invariance principle for coalescing random
walks. This result holds under a finite variance assumption and is thus
optimal. In previous works by Fontes et al. [Ann. Probab. 32 (2004) 2857-2883],
Newman et al. [Electron. J. Probab. 10 (2005) 21-60], the topology and
state-space required a moment of order for this convergence to
hold. The proof relies crucially on recent work of Schramm and Smirnov on
scaling limits of critical percolation in the plane. Our approach is
sufficiently simple that we can handle substantially more complicated
coalescing flows with little extra work - in particular similar results are
obtained in the case of coalescing Brownian motions on the Sierpinski gasket.
This is the first such result where the limiting paths do not enjoy the
noncrossing property.Comment: Published at http://dx.doi.org/10.1214/14-AOP957 in the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Weak convergence of the localized disturbance flow to the coalescing Brownian flow
We define a new state-space for the coalescing Brownian flow, also known as
the Brownian web, on the circle. The elements of this space are families of
order-preserving maps of the circle, depending continuously on two time
parameters and having a certain weak flow property. The space is equipped with
a complete separable metric. A larger state-space, allowing jumps in time, is
also introduced, and equipped with a Skorokhod-type metric, also complete and
separable. We prove that the coalescing Brownian flow is the weak limit in this
larger space of a family of flows which evolve by jumps, each jump arising from
a small localized disturbance of the circle. A local version of this result is
also obtained, in which the weak limit law is that of the coalescing Brownian
flow on the line. Our set-up is well adapted to time-reversal and our weak
limit result provides a new proof of time-reversibility of the coalescing
Brownian flow. We also identify a martingale associated with the coalescing
Brownian flow on the circle and use this to make a direct calculation of the
Laplace transform of the time to complete coalescence.Comment: Published at http://dx.doi.org/10.1214/13-AOP845 in the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org). arXiv admin note: substantial text
overlap with arXiv:0810.021
- …