2,465 research outputs found
Quantum Hall-like effect on strips due to geometry
In this Letter we present an exact calculation of the effective potential
which appears on a helicoidal strip. This potential leads to the appearance of
lcalized states at a distance \xi_0 from the central axis. The twist \omega of
the strip plays the role of a magnetic field and is responsable for the
appearance of these localized states and an effective transverse electric field
thus this is reminiscent of the quantum Hall effect. At very low temperatures
the twisted configuration of the strip may be stalilized by the electronic
states.Comment: 3 page
Establishing Effective Life-Style Ministries to New Zealand Maoris
Problem:
The Seventh-day Adventist Church has endeavoured to proclaim its unique message of the nearness of Christ\u27s return to the Maoris of New Zealand since 1885. In spite of repeated and intense efforts the results have been disappointingly meagre. The most success has been apparent when labours have been concentrated on the more practical needs that Maoris face. There is considerable evidence that Maoris still face serious problems in health and life-style, yet existing Adventist programmes relating to these matters do not attract a Maori audience. This project researches the reason why and seeks to establish effective life-style ministries to New Zealand Maoris
The anomalous chiral perturbation theory meson Lagrangian to order revisited
We present a revised and extended construction of the mesonic Lagrangian
density in chiral perturbation theory (ChPT) at order in the anomalous
(or epsilon) sector, . After improving several aspects
of the strategy we used originally, i.e., a more efficient application of
partial integration, the implementation of so-called Bianchi identities, and
additional trace relations, we find the new monomial sets to include 24
, 23 SU(3), and 5 SU(2) elements. Furthermore, we introduce 8
supplementary terms due to the extension of the chiral group to .Comment: 21 pages, Latex, using RevTe
Gapless Hartree-Fock Resummation Scheme for the O(N) Model
A modified selfconsistent Hartree-Fock approximation to the lambda*phi^4
theory with spontaneously broken O(N) symmetry is proposed. It preserves all
the desirable features, like conservation laws and thermodynamic consistency,
of the selfconsistent Dyson scheme generated from a 2PI functional, also known
as the Phi-derivable scheme, while simultaneously respecting the
Nambu-Goldstone theorem in the chiral-symmetry broken phase. Various
approximate resummation schemes are discussed.Comment: 13 pages, 10 figures / Version accepted by Phys. Rev. D: the
introduction has been expanded by a few remarks in order to further clarify
the goal of the pape
Spontaneously Broken Spacetime Symmetries and Goldstone's Theorem
Goldstone's theorem states that there is a massless mode for each broken
symmetry generator. It has been known for a long time that the naive
generalization of this counting fails to give the correct number of massless
modes for spontaneously broken spacetime symmetries. We explain how to get the
right count of massless modes in the general case, and discuss examples
involving spontaneously broken Poincare and conformal invariance.Comment: 4 pages; 1 figure; v2: minor corrections. version to appear on PR
Field theoretic description of the abelian and non-abelian Josephson effect
We formulate the Josephson effect in a field theoretic language which affords
a straightforward generalization to the non-abelian case. Our formalism
interprets Josephson tunneling as the excitation of pseudo-Goldstone bosons. We
demonstrate the formalism through the consideration of a single junction
separating two regions with a purely non-abelian order parameter and a sandwich
of three regions where the central region is in a distinct phase. Applications
to various non-abelian symmetry breaking systems in particle and condensed
matter physics are given.Comment: 10 pages no figure
The evolutionary dynamics of cooperation in collective search
How does cooperation arise in an evolutionary context? We approach this problem using a collective search paradigm where interactions are dynamic and there is competition for rewards. Using evolutionary simulations, we find that the unconditional sharing of information can be an evolutionary advantageous strategy without the need for conditional strategies or explicit reciprocation. Shared information acts as a recruitment signal and facilitates the formation of a self-organized group. Thus, the improved search efficiency of the collective bestows byproduct benefits onto the original sharer. A key mechanism is a visibility radius, where individuals have unconditional access to information about neighbors within a limited distance. Our results show that for a variety of initial conditions—including populations initially devoid of prosocial individuals—and across both static and dynamic fitness landscapes, we find strong selection pressure to evolve unconditional sharing
The Quantum Transverse Field Ising Model on an Infinite Tree from Matrix Product States
We give a generalization to an infinite tree geometry of Vidal's infinite
time-evolving block decimation (iTEBD) algorithm for simulating an infinite
line of quantum spins. We numerically investigate the quantum Ising model in a
transverse field on the Bethe lattice using the Matrix Product State ansatz. We
observe a second order phase transition, with certain key differences from the
transverse field Ising model on an infinite spin chain. We also investigate a
transverse field Ising model with a specific longitudinal field. When the
transverse field is turned off, this model has a highly degenerate ground state
as opposed to the pure Ising model whose ground state is only doubly
degenerate.Comment: 28 pages, 23 figures, PDFlate
Neutrino scattering off pair-breaking and collective excitations in superfluid neutron matter and in color-flavor locked quark matter
We calculate the correlation functions needed to describe the linear response
of superfluid matter, and go on to calculate the differential cross section for
neutral-current neutrino scattering in superfluid neutron matter and in
color-flavor locked quark matter (CFL). We report the first calculation of
scattering rates that includes neutrino interactions with both pair-breaking
excitations and low-lying collective excitations (Goldstone modes). Our results
apply both above and below the critical temperature, allowing use in
simulations of neutrino transport in supernovae and neutron stars.Comment: 22 pages, 9 figure
Quark description of the Nambu-Goldstone bosons in the color-flavor locked phase
We investigate the color-singlet order parameters and the quark description
of the Nambu-Goldstone (NG) bosons in the color-flavor locked (CFL) phase. We
put emphasis on the NG boson (phason) called ``H'' associated with the
symmetry breaking. We qualitatively argue the nature of H as
the second sound in the hydrodynamic regime. We articulate, based on a diquark
picture, how the structural change of the condensates and the associated NG
bosons occurs continuously from hadronic to CFL quark matter if the
quark-hadron continuity is realized. We sharpen the qualitative difference
between the flavor octet pions and the singlet phason. We propose a conjecture
that superfluid H matter undergoes a crossover to a superconductor with
tightly-bound diquarks, and then a crossover to superconducting matter with
diquarks dissociated.Comment: 14 pages, 1 table, 1 figure and confusing statements are correcte
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