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 - Funding Information:
We are grateful to Ksenia Bulycheva for collaboration at the early stages of this project. We also thank Dio Anninos, Andrei Bernevig, Sylvain Carrozza, Chethan Krishnan, Juan Maldacena, Daniel Roberts, Douglas Stanford and Edward Witten for useful discussions. The work of IRK was supported in part by the U.S. NSF under Grant No. PHY-1620059. The work of G. T. was supported in part by the Multidisciplinary University Research Initiative (MURI) Grant No. W911NF-14-1-0003 from U.S. Army Research Office (ARO) and by DOE Grant No. de-sc0007870.

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.

UR - http://www.scopus.com/inward/record.url?scp=85048081784&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85048081784&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.97.106023

DO - 10.1103/PhysRevD.97.106023

M3 - Article

AN - SCOPUS:85048081784

VL - 97

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 10

M1 - 106023

ER -