93 research outputs found
Yangian Symmetry and Quantum Inverse Scattering Method for the One-Dimensional Hubbard Model
We develop the quantum inverse scattering method for the one-dimensional
Hubbard model on the infinite interval at zero density. -matrix and
monodromy matrix are obtained as limits from their known counterparts on the
finite interval. The -matrix greatly simplifies in the considered limit. The
new -matrix contains a submatrix which turns into the rational -matrix of
the XXX-chain by an appropriate reparametrization. The corresponding submatrix
of the monodromy matrix thus provides a representation of the Y(su(2)) Yangian.
From its quantum determinant we obtain an infinite series of mutually commuting
Yangian invariant operators which includes the Hamiltonian.Comment: 14 pages, LaTeX, no figures, minor change
The Hubbard chain: Lieb-Wu equations and norm of the eigenfunctions
We argue that the square of the norm of the Hubbard wave function is
proportional to the determinant of a matrix, which is obtained by linearization
of the Lieb-Wu equations around a solution. This means that in the vicinity of
a solution the Lieb-Wu equations are non-degenerate, if the corresponding wave
function is non-zero. We further derive an action that generates the Lieb-Wu
equations and express our determinant formula for the square of the norm in
terms of the Hessian determinant of this action.Comment: 11 pages, Late
Asymptotic form of two-point correlation function of the XXZ spin chain
Correlation functions of the XXZ spin chain in the critical regime is studied
at zero-temperature. They are exactly represented in the Fredholm determinant
form and are related with an operator-valued Riemann-Hilbert problem. Analyzing
this problem we prove that a two-point correlation function consisting of
sufficiently separated spin operators is expressed by power-functions of the
distance between those operators.Comment: 9 pages, LaTeX2e (+ amssymb, amsthm); Proof of Lemma 1 is revise
SU(2)xSU(2) Invariant Scattering Matrix of the Hubbard Model
We consider the one-dimensional half-filled Hubbard model. We show that the
excitation spectrum is given by the scattering states of four elementary
excitations, which form the fundamental representation of .
We determine the exact two-particle Scattering matrix, which a solution of the
Yang-Baxter equation and reflects the symmetry of the model. The
results for repulsive and attractive Hubbard model are related by an
interchange of spin and charge degrees of freedom.Comment: 29 pages, jyTeX (macro included - just TeX the file) ITP-SB-93-45,
BONN-HE-93-3
A note on density correlations in the half-filled Hubbard model
We consider density-density correlations in the one-dimensional Hubbard model
at half filling. On intuitive grounds one might expect them to exhibit an
exponential decay. However, as has been noted recently, this is not obvious
from the Bethe Ansatz/conformal field theory (BA/CFT) approach. We show that by
supplementing the BA/CFT analysis with simple symmetry arguments one can easily
prove that correlations of the lattice density operators decay exponentially.Comment: 3 pages, RevTe
Odyssey Towards a Sirenic Thinking: An Attempt at a Self-Criticism of the Listening Paradigm Within Sound Studies
This text departs from a contradictory claim in deaf studies and sound studies: both disciplines describe a hierarchical regime of the sensible – visuocentrism and audiocentrism – which they try to counter with conceptualisations as “acoustemology” or “deaf gain.” However, as we argue, they both thereby erect what they claim to overcome: a sensual regime that privileges one sense over another and a restricted conception of subjectivity deriving from it. First, we draw a philosophical line in the critique of sensual regimes. Then we propose a figure for the transcendence of the separation of the sensible: in re-reading of the myth of Odysseus and the sirens, we engage various examples from literature, art, and acoustics to describe sirens as a mythological and technical archetype of the transcendence of the sensual regime, as well as reified subjectivity. The question, then, is not how to escape the sirens, but how they can be approached. It is necessary, we argue, for sound studies to develop a critical self-consciousness of its own restricted concepts in order to move from sonic thinking towards a sirenic thinking
Integro-Difference Equation for a correlation function of the spin- Heisenberg XXZ chain
We consider the Ferromagnetic-String-Formation-Probability correlation
function (FSFP) for the spin- Heisenberg XXZ chain. We construct a
completely integrable system of integro-difference equations (IDE), which has
the FSFP as a -function. We derive the associated Riemann-Hilbert problem
and obtain the large distance asymptotics of the FSFP correlator in some
limiting cases.Comment: 14 pages, latex+epsf, 1 figur
Krankheit gestalten
Moulagen - plastische Krankheitsdarstellungen - waren wichtige Dokumentations- und Lehrobjekte der Medizin. Die Moulagenbildner*innen galten in der Medizingeschichte oft als skurrile Außenseiter*innen, deren Arbeit von alchemistisch anmutender Geheimnistuerei umgeben war. Henrik Eßler widmet sich erstmals der Berufsgeschichte dieser unterschätzten Spezialist*innen. Dabei stellt er einerseits die Bedeutung der Moulage heraus, die weit über eine »naturgetreue« Nachbildung hinausging. Andererseits rückt er die Stellung der Moulagenbildner*innen im wissenschaftlichen Arbeitsprozess in ein neues Licht: Sie waren nicht nur ausführendes Organ, sondern Kooperationspartner*innen im Forschungszusammenhang
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