QCD-like theories can be engineered to remain in a confined phase when compactified on an arbitrarily small circle, where their features may be studied quantitatively in a controlled fashion. Previous work has elucidated the generation of a nonperturbative mass gap and the spontaneous breaking of chiral symmetry in this regime. Here, we study the rich spectrum of hadronic states, including glueball, meson, and baryon resonances. We find an exponentially growing Hagedorn density of states, as well as the emergence of nonperturbative energy scales given by iterated exponentials of the inverse Yang-Mills coupling g2.
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We are grateful to M. Ünsal for helpful discussions. This work was supported, in part, by the U.S. Department of Energy via Grant No. DE-FG02-00ER-41132 (A. C.) and Grant No. DE-SC0011637 (K. A. and L. Y.) and by a Discovery Grant of the National Science and Engineering Research Council of Canada (E. P.). L. Yaffe thanks the University of Regensburg and the Alexander von Humboldt foundation for their generous support and hospitality during completion of this work.
© 2017 American Physical Society.