235 research outputs found
Algebraic Linearization of Dynamics of Calogero Type for any Coxeter Group
Calogero-Moser systems can be generalized for any root system (including the
non-crystallographic cases). The algebraic linearization of the generalized
Calogero-Moser systems and of their quadratic (resp. quartic) perturbations are
discussed.Comment: LaTeX2e, 13 pages, no figure
Calogero-Moser Models III: Elliptic Potentials and Twisting
Universal Lax pairs of the root type with spectral parameter and independent
coupling constants for twisted non-simply laced Calogero-Moser models are
constructed. Together with the Lax pairs for the simply laced models and
untwisted non-simply laced models presented in two previous papers, this
completes the derivation of universal Lax pairs for all of the Calogero-Moser
models based on root systems. As for the twisted models based on B_n, C_n and
BC_nroot systems, a new type of potential term with independent coupling
constants can be added without destroying integrability. They are called
extended twisted models. All of the Lax pairs for the twisted models presented
here are new, except for the one for the F_4 model based on the short roots.
The Lax pairs for the twisted G_2 model have some novel features. Derivation of
various functions, twisted and untwisted, appearing in the Lax pairs for
elliptic potentials with the spectral parameter is provided. The origin of the
spectral parameter is also naturally explained. The Lax pairs with spectral
parameter, twisted and untwisted, for the hyperbolic, the trigonometric and the
rational potential models are obtained as degenerate limits of those for the
elliptic potential models.Comment: LaTeX2e with amsfonts.sty, 36 pages, no figure
Calogero-Moser Models V: Supersymmetry and Quantum Lax Pair
It is shown that the Calogero-Moser models based on all root systems of the
finite reflection groups (both the crystallographic and non-crystallographic
cases) with the rational (with/without a harmonic confining potential),
trigonometric and hyperbolic potentials can be simply supersymmetrised in terms
of superpotentials. There is a universal formula for the supersymmetric ground
state wavefunction. Since the bosonic part of each supersymmetric model is the
usual quantum Calogero-Moser model, this gives a universal formula for its
ground state wavefunction and energy, which is determined purely algebraically.
Quantum Lax pair operators and conserved quantities for all the above
Calogero-Moser models are established.Comment: LaTeX2e, 31 pages, no figure
Generalised Calogero-Moser models and universal Lax pair operators
Calogero-Moser models can be generalised for all of the finite reflection
groups. These include models based on non-crystallographic root systems, that
is the root systems of the finite reflection groups, H_3, H_4, and the dihedral
group I_2(m), besides the well-known ones based on crystallographic root
systems, namely those associated with Lie algebras. Universal Lax pair
operators for all of the generalised Calogero-Moser models and for any choices
of the potentials are constructed as linear combinations of the reflection
operators. The consistency conditions are reduced to functional equations for
the coefficient functions of the reflection operators in the Lax pair. There
are only four types of such functional equations corresponding to the
two-dimensional sub-root systems, A_2, B_2, G_2, and I_2(m). The root type and
the minimal type Lax pairs, derived in our previous papers, are given as the
simplest representations. The spectral parameter dependence plays an important
role in the Lax pair operators, which bear a strong resemblance to the Dunkl
operators, a powerful tool for solving quantum Calogero-Moser models.Comment: 37 pages, LaTeX2e, no macro, no figur
Quantum Inozemtsev model, quasi-exact solvability and N-fold supersymmetry
Inozemtsev models are classically integrable multi-particle dynamical systems
related to Calogero-Moser models. Because of the additional q^6 (rational
models) or sin^2(2q) (trigonometric models) potentials, their quantum versions
are not exactly solvable in contrast with Calogero-Moser models. We show that
quantum Inozemtsev models can be deformed to be a widest class of partly
solvable (or quasi-exactly solvable) multi-particle dynamical systems. They
posses N-fold supersymmetry which is equivalent to quasi-exact solvability. A
new method for identifying and solving quasi-exactly solvable systems, the
method of pre-superpotential, is presented.Comment: LaTeX2e 28 pages, no figure
Quadratic Algebra associated with Rational Calogero-Moser Models
Classical Calogero-Moser models with rational potential are known to be
superintegrable. That is, on top of the r involutive conserved quantities
necessary for the integrability of a system with r degrees of freedom, they
possess an additional set of r-1 algebraically and functionally independent
globally defined conserved quantities. At the quantum level, Kuznetsov
uncovered the existence of a quadratic algebra structure as an underlying key
for superintegrability for the models based on A type root systems. Here we
demonstrate in a universal way the quadratic algebra structure for quantum
rational Calogero-Moser models based on any root systems.Comment: 19 pages, LaTeX2e, no figure
The Dn Ruijsenaars-Schneider model
The Lax pair of the Ruijsenaars-Schneider model with interaction potential of
trigonometric type based on Dn Lie algebra is presented. We give a general form
for the Lax pair and prove partial results for small n. Liouville integrability
of the corresponding system follows a series of involutive Hamiltonians
generated by the characteristic polynomial of the Lax matrix. The rational case
appears as a natural degeneration and the nonrelativistic limit exactly leads
to the well-known Calogero-Moser system associated with Dn Lie algebra.Comment: LaTeX2e, 14 pages; more remarks are added in the last sectio
Quantum Calogero-Moser Models: Integrability for all Root Systems
The issues related to the integrability of quantum Calogero-Moser models
based on any root systems are addressed. For the models with degenerate
potentials, i.e. the rational with/without the harmonic confining force, the
hyperbolic and the trigonometric, we demonstrate the following for all the root
systems: (i) Construction of a complete set of quantum conserved quantities in
terms of a total sum of the Lax matrix (L), i.e. (\sum_{\mu,\nu\in{\cal
R}}(L^n)_{\mu\nu}), in which ({\cal R}) is a representation space of the
Coxeter group. (ii) Proof of Liouville integrability. (iii) Triangularity of
the quantum Hamiltonian and the entire discrete spectrum. Generalised Jack
polynomials are defined for all root systems as unique eigenfunctions of the
Hamiltonian. (iv) Equivalence of the Lax operator and the Dunkl operator. (v)
Algebraic construction of all excited states in terms of creation operators.
These are mainly generalisations of the results known for the models based on
the (A) series, i.e. (su(N)) type, root systems.Comment: 45 pages, LaTeX2e, no figure
Comprehensive inventory of protein complexes in the Protein Data Bank from consistent classification of interfaces
<p>Abstract</p> <p>Background</p> <p>Protein-protein interactions are ubiquitous and essential for all cellular processes. High-resolution X-ray crystallographic structures of protein complexes can reveal the details of their function and provide a basis for many computational and experimental approaches. Differentiation between biological and non-biological contacts and reconstruction of the intact complex is a challenging computational problem. A successful solution can provide additional insights into the fundamental principles of biological recognition and reduce errors in many algorithms and databases utilizing interaction information extracted from the Protein Data Bank (PDB).</p> <p>Results</p> <p>We have developed a method for identifying protein complexes in the PDB X-ray structures by a four step procedure: (1) comprehensively collecting all protein-protein interfaces; (2) clustering similar protein-protein interfaces together; (3) estimating the probability that each cluster is relevant based on a diverse set of properties; and (4) combining these scores for each PDB entry in order to predict the complex structure. The resulting clusters of biologically relevant interfaces provide a reliable catalog of evolutionary conserved protein-protein interactions. These interfaces, as well as the predicted protein complexes, are available from the Protein Interface Server (PInS) website (see Availability and requirements section).</p> <p>Conclusion</p> <p>Our method demonstrates an almost two-fold reduction of the annotation error rate as evaluated on a large benchmark set of complexes validated from the literature. We also estimate relative contributions of each interface property to the accurate discrimination of biologically relevant interfaces and discuss possible directions for further improving the prediction method.</p
- …