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Calogero-Moser System


Calogero-Moser systems are integrable systems with singular pair interactions. The rational Calogero-Moser system is the Hamiltonian system defined by

 H=1/2sum_(i=1)^Np_i^2+g^2sum_(1<=i<j<=N)1/((q_i-q_j)^2),
(1)

where N>=2, the coordinates q_i are distinct real numbers, the momenta p_i are real, and g>0. Hamilton's equations give

q^._i=p_i
(2)
p^._i=2g^2sum_(j!=i)1/((q_i-q_j)^3).
(3)

Its Lax pair can be written using matrices L and A with entries

L_(jj)=p_j
(4)
L_(jk)=(ig)/(q_j-q_k)
(5)
A_(jj)=-igsum_(l!=j)1/((q_j-q_l)^2)
(6)
A_(jk)=(ig)/((q_j-q_k)^2),
(7)

where the off-diagonal formulas apply for j!=k and i=sqrt(-1) is the imaginary unit. The evolution equation is

 L^.=[A,L],
(8)

so the eigenvalues of L are conserved. The matrix traces

 I_k=1/kTr(L^k)
(9)

for k=1, ..., N are integrals of motion that commute under the Poisson bracket and are functionally independent on a dense open set. In particular, I_2=H (Moser 1975; Etingof 2007, pp. 11-19).

Adding the harmonic term (omega^2/2)sum_(i)q_i^2, where omega>0, gives equilibrium coordinates

 q_i=sqrt(g/omega)h_i,
(10)

where the h_i are the zeros of the Hermite polynomial H_N(x) with leading coefficient 2^N (Odake and Sasaki 2002). The quantum rational model with harmonic confinement is a Calogero-Sutherland model.

CalogeroMoserEquilibria

The equilibrium coordinates for g=omega=1 and N=3, 5, and 8 are illustrated above. The blue curves are the Hermite polynomials multiplied by e^(-x^2/2) and scaled independently for display. This positive factor preserves their zeros, which are marked as the orange equilibrium positions.


See also

Calogero-Sutherland Model, Hamiltonian System, Integrable System, Integral of Motion, Lax Pair, Poisson Bracket

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References

Calogero, F. "Solution of the One-Dimensional N-Body Problems with Quadratic and/or Inversely Quadratic Pair Potentials." J. Math. Phys. 12, 419-436, 1971. https://doi.org/10.1063/1.1665604.Etingof, P. Calogero-Moser Systems and Representation Theory. Zürich, Switzerland: European Mathematical Society, 2007. https://doi.org/10.4171/034.Moser, J. "Three Integrable Hamiltonian Systems Connected with Isospectral Deformations." Adv. Math. 16, 197-220, 1975. https://doi.org/10.1016/0001-8708(75)90151-6.Odake, S. and Sasaki, R. "Polynomials Associated with Equilibrium Positions in Calogero-Moser Systems." J. Phys. A: Math. Gen. 35, 8283-8314, 2002. https://doi.org/10.1088/0305-4470/35/39/312. https://arxiv.org/abs/hep-th/0206172.

Cite this as:

Weisstein, Eric W. "Calogero-Moser System." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Calogero-MoserSystem.html

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