Breaking the chain

We consider the motion of a Brownian particle in $\mathbb{R}$, moving between a particle fixed at the origin and another moving deterministically away at slow speed $\epsilon>0$. The middle particle interacts with its neighbours via a potential of finite range $b>0$, with a unique minimum at $a>0$, where $b<2a$. We say that the chain of particles breaks on the left- or right-hand side when the middle particle is greater than a distance $b$ from its left or right neighbour, respectively. We study the asymptotic location of the first break of the chain in the limit of small noise, in the case where $\epsilon = \epsilon(\sigma)$ and $\sigma>0$ is the noise intensity.Comment: 13 pages, 2 figures. v2: Corrected a mistake in proof of second part of main theore

Disorder and chain superconductivity in YBa_2Cu_3O_{7-\delta}

The effects of chain disorder on superconductivity in YBa_2Cu_3O_{7-\delta} are discussed within the context of a proximity model. Chain disorder causes both pair-breaking and localization. The hybridization of chain and plane wavefunctions reduces the importance of localization, so that the transport anisotropy remains large in the presence of a finite fraction $\delta$ of oxygen vacancies. Penetration depth and specific heat measurements probe the pair-breaking effects of chain disorder, and are discussed in detail at the level of the self-consistent T-matrix approximation. Quantitative agreement with these experiments is found when chain disorder is present.Comment: 4 pages, 2 figures, submitted to PRB rapid communication

Quantum Breaking of Elastic String

Breaking of an atomic chain under stress is a collective many-particle tunneling phenomenon. We study classical dynamics in imaginary time by using conformal mapping technique, and derive an analytic formula for the probability of breaking. The result covers a broad temperature interval and interpolates between two regimes: tunneling and thermal activation. Also, we consider the breaking induced by an ultrasonic wave propagating in the chain, and propose to observe it in an STM experiment.Comment: 8 pages, RevTeX 3.0, Landau Institute preprint 261/643

Comment to "Imaging the atomic orbitals of carbon atomic chains with field-emission electron microscopy"

The observation of a stable doublet pattern in the field-emission electron microscopy of a linear atomic chain requires a stable mechanism breaking the axial symmetry, which is not identified correctly by Mikhailovskij et al. [Phys. Rev. B 80, 165404 (2009)]. Using microscopic calculations, we attribute the observed pattern to the symmetry breaking produced by the ligand where the chain is attached, plus carbon pi-bonding alternation.Comment: 2 pages 1 fig, PRB commen

Entanglement and Spontaneous Symmetry Breaking in Quantum Spin Models

It is shown that spontaneous symmetry breaking does not modify the ground-state entanglement of two spins, as defined by the concurrence, in the XXZ- and the transverse field Ising-chain. Correlation function inequalities, valid in any dimensions for these models, are presented outlining the regimes where entanglement is unaffected by spontaneous symmetry breaking

Supersymmetry approach to the random heteropolymer theory

The effective equation of motion that describes the different monomer alternation along the heteropolymer chain is proposed. On this basis the supersymmetry field scheme is built up to analyze memory and ergodicity breaking effects.Comment: 10 pages, 1 figur

Breaking Down the Chain: A Guide to the Soft Drink Industry

Provides an overview of the soft drink industry's earnings, structure, markets, and determinants of demand; major players; supply chain; marketing strategies; and policy and legislative actions in response to the sugar-sweetened beverage tax