413,607 research outputs found
Composite quantum collision models
A collision model (CM) is a framework to describe open quantum dynamics. In
its {\it memoryless} version, it models the reservoir as
consisting of a large collection of elementary ancillas: the dynamics of the
open system results from successive "collisions" of
with the ancillas of . Here, we present a general formulation of
memoryless {\it composite} CMs, where is partitioned into the very
open system under study coupled to one or more auxiliary systems .
Their composite dynamics occurs through internal - collisions
interspersed with external ones involving and the reservoir . We show that important known instances of quantum {\it non-Markovian}
dynamics of -- such as the emission of an atom into a reservoir featuring a
Lorentzian, or multi-Lorentzian, spectral density or a qubit subject to random
telegraph noise -- can be mapped on to such {\it memoryless} composite CMs.Comment: 12 pages, 4 figure
Large N Scalars: From Glueballs to Dynamical Higgs Models
We construct effective Lagrangians, and corresponding counting schemes, valid
to describe the dynamics of the lowest lying large N stable massive composite
state emerging in strongly coupled theories. The large N counting rules can now
be employed when computing quantum corrections via an effective Lagrangian
description. The framework allows for systematic investigations of composite
dynamics of non-Goldstone nature. Relevant examples are the lightest glueball
states emerging in any Yang-Mills theory. We further apply the effective
approach and associated counting scheme to composite models at the electroweak
scale. To illustrate the formalism we consider the possibility that the Higgs
emerges as: the lightest glueball of a new composite theory; the large N scalar
meson in models of dynamical electroweak symmetry breaking; the large N
pseudodilaton useful also for models of near-conformal dynamics. For each of
these realisations we determine the leading N corrections to the electroweak
precision parameters. The results nicely elucidate the underlying large N
dynamics and can be used to confront first principle lattice results featuring
composite scalars with a systematic effective approach.Comment: 15 pages ReVTeX, 3 figure
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