TY - JOUR

T1 - Spectra of eigenstates in fermionic tensor quantum mechanics

AU - Klebanov, Igor R.

AU - Milekhin, Alexey

AU - Popov, Fedor

AU - Tarnopolsky, Grigory

N1 - Publisher Copyright:
© 2018 authors. Published by the American Physical Society.

PY - 2018/5/15

Y1 - 2018/5/15

N2 - We study the O(N1)×O(N2)×O(N3) symmetric quantum mechanics of 3-index Majorana fermions. When the ranks Ni are all equal, this model has a large N limit which is dominated by the melonic Feynman diagrams. We derive an integral formula which computes the number of group invariant states for any set of Ni. It is non-vanishing only when each Ni is even. For equal ranks the number of singlets exhibits rapid growth with N: it jumps from 36 in the O(4)3 model to 595 354 780 in the O(6)3 model. We derive bounds on the values of energy, which show that they scale at most as N3 in the large N limit, in agreement with expectations. We also show that the splitting between the lowest singlet and non-singlet states is of order 1/N. For N3=1 the tensor model reduces to O(N1)×O(N2) fermionic matrix quantum mechanics, and we find a simple expression for the Hamiltonian in terms of the quadratic Casimir operators of the symmetry group. A similar expression is derived for the complex matrix model with SU(N1)×SU(N2)×U(1) symmetry. Finally, we study the N3=2 case of the tensor model, which gives a more intricate complex matrix model whose symmetry is only O(N1)×O(N2)×U(1). All energies are again integers in appropriate units, and we derive a concise formula for the spectrum. The fermionic matrix models we studied possess standard 't Hooft large N limits where the ground state energies are of order N2, while the energy gaps are of order 1.

AB - We study the O(N1)×O(N2)×O(N3) symmetric quantum mechanics of 3-index Majorana fermions. When the ranks Ni are all equal, this model has a large N limit which is dominated by the melonic Feynman diagrams. We derive an integral formula which computes the number of group invariant states for any set of Ni. It is non-vanishing only when each Ni is even. For equal ranks the number of singlets exhibits rapid growth with N: it jumps from 36 in the O(4)3 model to 595 354 780 in the O(6)3 model. We derive bounds on the values of energy, which show that they scale at most as N3 in the large N limit, in agreement with expectations. We also show that the splitting between the lowest singlet and non-singlet states is of order 1/N. For N3=1 the tensor model reduces to O(N1)×O(N2) fermionic matrix quantum mechanics, and we find a simple expression for the Hamiltonian in terms of the quadratic Casimir operators of the symmetry group. A similar expression is derived for the complex matrix model with SU(N1)×SU(N2)×U(1) symmetry. Finally, we study the N3=2 case of the tensor model, which gives a more intricate complex matrix model whose symmetry is only O(N1)×O(N2)×U(1). All energies are again integers in appropriate units, and we derive a concise formula for the spectrum. The fermionic matrix models we studied possess standard 't Hooft large N limits where the ground state energies are of order N2, while the energy gaps are of order 1.

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U2 - 10.1103/PhysRevD.97.106023

DO - 10.1103/PhysRevD.97.106023

M3 - Article

AN - SCOPUS:85048081784

SN - 2470-0010

VL - 97

JO - Physical Review D

JF - Physical Review D

IS - 10

M1 - 106023

ER -