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The spectra of two-dimensional su(2) gauge theories coupled to a single massless Majorana fermion in integer representations, J, are numerically investigated using the discrete light-cone Hamiltonian. One of our aims is to explore the possible presence of massless states for J > 2 in spite of the absence of a continuous symmetry. After comparing to existing results for J = 1 (adjoint fermions), we present results for J = 2, 3, 4. As expected, for J = 2 there are no massless states but in contrast to the J = 1 theory, the lightest state is a boson. We find exact massless modes in the bosonic and fermionic sector for all values of total momentum for J = 3 and J = 4 and, in each sector, the number of massless modes grows with the value of the total momentum. In addition to the spectrum, we present results on the particle number and momentum fraction distributions and argue for a separation of bulk states from edge states.
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Observation of dynamical fermionization
The wave function of a Tonks-Girardeau (T-G) gas of strongly interacting bosons in one dimension maps onto the absolute value of the wave function of a noninteracting Fermi gas. Although this fermionization makes many aspects of the two gases identical, their equilibrium momentum distributions are quite different. We observed dynamical fermionization, where the momentum distribution of a T-G gas evolves from bosonic to fermionic after its axial confinement is removed. The asymptotic momentum distribution after expansion in one dimension is the distribution of rapidities, which are the conserved quantities associated with many-body integrable systems. Our measurements agree well with T-G gas theory. We also studied momentum evolution after the trap depth is suddenly changed to a new nonzero value, and we observed the theoretically predicted bosonic-fermionic oscillations.
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- PAR ID:
- 10141516
- Publisher / Repository:
- American Association for the Advancement of Science (AAAS)
- Date Published:
- Journal Name:
- Science
- Volume:
- 367
- Issue:
- 6485
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- p. 1461-1464
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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