## Electronic Communications in Probability

- Electron. Commun. Probab.
- Volume 16 (2011), paper no. 26, 271-282.

### Survival and extinction of caring double-branching annihilating random walk

#### Abstract

Branching annihilating random walk (BARW) is a generic term for a class of interacting
particle systems on $\mathbb{Z}^d$ in which, as time evolves, particles execute random
walks, produce offspring (on neighbouring sites) and (instantaneously) disappear when they
meet other particles. Much of the interest in such models stems from the fact that they
typically lack a monotonicity property called *attractiveness*, which in general
makes them exceptionally hard to analyse and in particular highly sensitive in their
qualitative long-time behaviour to even slight alterations of the branching and
annihilation mechanisms. In this short note, we introduce so-called *caring*
double-branching annihilating random walk (cDBARW) on $\mathbb{Z}$, and investigate its
long-time behaviour. It turns out that it either allows survival with positive probability
if the branching rate is greater than $1/2$, or a.s. extinction if the branching rate is
smaller than $1/3$ and (additionally) branchings are only admitted for particles which
have at least one neighbouring particle (so-called 'cooperative branching'). Further, we
show a.s. extinction for all branching rates for a variant of this model, where branching
is only allowed if offspring can be placed at odd distance between each other. It is the
latter (extinction-type) results which seem remarkable, since they appear to hint at a
general extinction result for a non-trivial parameter range in the so-called
'parity-preserving universality class', suggesting the existence of a 'true' phase
transition. The rigorous proof of such a non-trivial phase transition remains a
particularly challenging open problem.

#### Article information

**Source**

Electron. Commun. Probab. Volume 16 (2011), paper no. 26, 271-282.

**Dates**

Accepted: 23 May 2011

First available in Project Euclid: 7 June 2016

**Permanent link to this document**

https://projecteuclid.org/euclid.ecp/1465261982

**Digital Object Identifier**

doi:10.1214/ECP.v16-1631

**Mathematical Reviews number (MathSciNet)**

MR2802043

**Zentralblatt MATH identifier**

1225.60149

**Subjects**

Primary: 60K35: Interacting random processes; statistical mechanics type models; percolation theory [See also 82B43, 82C43]

Secondary: 60J80: Branching processes (Galton-Watson, birth-and-death, etc.) 60J27: Continuous-time Markov processes on discrete state spaces

**Keywords**

Branching Annihilating Random Walk extinction survival interface duality swapping voter model

**Rights**

This work is licensed under a Creative Commons Attribution 3.0 License.

#### Citation

Blath, Jochen; Kurt, Noemi. Survival and extinction of caring double-branching annihilating random walk. Electron. Commun. Probab. 16 (2011), paper no. 26, 271--282. doi:10.1214/ECP.v16-1631. https://projecteuclid.org/euclid.ecp/1465261982