113 research outputs found
On O(1) contributions to the free energy in Bethe Ansatz systems: the exact g-function
We investigate the sub-leading contributions to the free energy of Bethe
Ansatz solvable (continuum) models with different boundary conditions. We show
that the Thermodynamic Bethe Ansatz approach is capable of providing the O(1)
pieces if both the density of states in rapidity space and the quadratic
fluctuations around the saddle point solution to the TBA are properly taken
into account. In relativistic boundary QFT the O(1) contributions are directly
related to the exact g-function. In this paper we provide an all-orders proof
of the previous results of P. Dorey et al. on the g-function in both massive
and massless models. In addition, we derive a new result for the g-function
which applies to massless theories with arbitrary diagonal scattering in the
bulk.Comment: 28 pages, 2 figures, v2: minor corrections, v3: minor corrections and
references adde
Excited Boundary TBA in the Tricritical Ising Model
By considering the continuum scaling limit of the RSOS lattice model
of Andrews-Baxter-Forrester with integrable boundaries, we derive excited state
TBA equations describing the boundary flows of the tricritical Ising model.
Fixing the bulk weights to their critical values, the integrable boundary
weights admit a parameter which plays the role of the perturbing
boundary field and induces the renormalization group flow between
boundary fixed points. The boundary TBA equations determining the RG flows are
derived in the example. The
induced map between distinct Virasoro characters of the theory are specified in
terms of distribution of zeros of the double row transfer matrix.Comment: Latex, 14 pages - Talk given at the Landau meeting "CFT and
Integrable Models", Sept. 2002 - v2: some statements about
perturbations correcte
Unusual presentation of fatal disseminated varicella zoster virus infection in a patient with lupus nephritis: A case report
Background: The risk of life-threatening complications, such as visceral disseminated varicella zoster virus (VZV) infection, is greater in immunosuppressed individuals, such as systemic lupus erythematosus (SLE) patients. Case presentation: Here, a case is reported of a Caucasian woman diagnosed with lupus nephritis and anti-phospholipid syndrome, who was subjected to mycophenolate mofetil and high-dose steroid remission-induction therapy. Two months later she developed abdominal pain followed by a fatal rapid multi-organ failure. As no typical skin rashes were evident, death was initially attributed to catastrophic anti-phospholipid syndrome. However, autopsy and virological examinations on archival material revealed a disseminated VZV infection. Conclusions: Overall, this case highlights the importance of having a high clinical suspicion of fatal VZV infections in heavily immunosuppressed SLE patients even when typical signs and symptoms are lacking
The solution of the quantum T-system for arbitrary boundary
We solve the quantum version of the -system by use of quantum
networks. The system is interpreted as a particular set of mutations of a
suitable (infinite-rank) quantum cluster algebra, and Laurent positivity
follows from our solution. As an application we re-derive the corresponding
quantum network solution to the quantum -system and generalize it to
the fully non-commutative case. We give the relation between the quantum
-system and the quantum lattice Liouville equation, which is the quantized
-system.Comment: 24 pages, 18 figure
Nonlinear integral equations for finite volume excited state energies of the O(3) and O(4) nonlinear sigma-models
We propose nonlinear integral equations for the finite volume one-particle
energies in the O(3) and O(4) nonlinear sigma-models. The equations are written
in terms of a finite number of components and are therefore easier to solve
numerically than the infinite component excited state TBA equations proposed
earlier. Results of numerical calculations based on the nonlinear integral
equations and the excited state TBA equations agree within numerical precision.Comment: numerical results adde
Knot invariants from rational conformal field theories
A framework for studying knot and link invariants from any rational conformal
field theory is developed. In particular, minimal models, superconformal models
and models are studied. The invariants are related to the invariants
obtained from the Wess-Zumino models associated with the coset representations
of these models. Possible Chern-Simons representation of these models is also
indicated. This generalises the earlier work on knot and link invariants from
Chern-Simons theories.Comment: 18pages+6 figures (available on request through email
Boundary Flows in general Coset Theories
In this paper we study the boundary effects for off-critical integrable field
theories which have close analogs with integrable lattice models. Our models
are the coset conformal field theories
perturbed by integrable boundary and bulk operators. The boundary interactions
are encoded into the boundary reflection matrix. Using the TBA method, we
verify the flows of the conformal BCs by computing the boundary entropies.
These flows of the BCs have direct interpretations for the fusion RSOS lattice
models. For super CFTs () we show that these flows are possible only for
the Neveu-Schwarz sector and are consistent with the lattice results. The
models we considered cover a wide class of integrable models. In particular, we
show how the the impurity spin is screened by electrons for the -channel
Kondo model by taking limit. We also study the problem using an
independent method based on the boundary roaming TBA. Our numerical results are
consistent with the boundary CFTs and RSOS TBA analysis.Comment: 22 pages, 3 postscript figure file
On the Classification of Diagonal Coset Modular Invariants
We relate in a novel way the modular matrices of GKO diagonal cosets without
fixed points to those of WZNW tensor products. Using this we classify all
modular invariant partition functions of
for all positive integer level , and for all and infinitely many (in fact, for
each a positive density of ). Of all these classifications, only that
for had been known. Our lists include many
new invariants.Comment: 24 pp (plain tex
Fractional Superstrings with Space-Time Critical Dimensions Four and Six
We propose possible new string theories based on local world-sheet symmetries
corresponding to extensions of the Virasoro algebra by fractional spin
currents. They have critical central charges and Minkowski
space-time dimensions for an integer. We present evidence
for their existence by constructing modular invariant partition functions and
the massless particle spectra. The dimension and strings have
space-time supersymmetry.Comment: 9 page
Unitarity of rational N=2 superconformal theories
We demonstrate that all rational models of the N=2 super Virasoro algebra are
unitary. Our arguments are based on three different methods: we determine Zhu's
algebra (for which we give a physically motivated derivation) explicitly for
certain theories, we analyse the modular properties of some of the vacuum
characters, and we use the coset realisation of the algebra in terms of su_2
and two free fermions.
Some of our arguments generalise to the Kazama-Suzuki models indicating that
all rational N=2 supersymmetric models might be unitary.Comment: LaTeX (+amssym.def), 28 pages; minor changes in content, some
references added, final versio
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