Tin Sulejmanpasic
North Carolina State University
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Featured researches published by Tin Sulejmanpasic.
Physical Review Letters | 2016
Alireza Behtash; Gerald V. Dunne; Thomas Schäfer; Tin Sulejmanpasic; Mithat Unsal
In the context of two illustrative examples from supersymmetric quantum mechanics we show that the semiclassical analysis of the path integral requires complexification of the configuration space and action, and the inclusion of complex saddle points, even when the parameters in the action are real. We find new exact complex saddles, and show that without their contribution the semiclassical expansion is in conflict with basic properties such as the positive semidefiniteness of the spectrum, as well as constraints of supersymmetry. Generic saddles are not only complex, but also possibly multivalued and even singular. This is in contrast to instanton solutions, which are real, smooth, and single valued. The multivaluedness of the action can be interpreted as a hidden topological angle, quantized in units of π in supersymmetric theories. The general ideas also apply to nonsupersymmetric theories.
Physical Review Letters | 2015
Alireza Behtash; Tin Sulejmanpasic; Thomas Schäfer; Mithat Unsal
We demonstrate the existence of hidden topological angles (HTAs) in a large class of quantum field theories and quantum mechanical systems. HTAs are distinct from theta-parameters in the lagrangian. They arise as invariant angle associated with saddle points of the complexified path integral and their descent manifolds (Lefschetz thimbles). Physical effects of HTAs become most transparent upon analytic continuation in n f to non-integer number of flavors, reducing in the integer n f limit to a Z2 valued phase difference between dominant saddles. In N = 1 super Yang-Mills theory we demonstrate the microscopic mechanism for the vanishing of the gluon condensate. The same effect leads to an anomalously small condensate in a QCD-like SU(N) gauge theory with fermions in the two-index representation. The basic phenomenon is that, contrary to folklore, the gluon condensate can receive both positive and negative contributions in a semi-classical expansion. In quantum mechanics, a HTA leads to a difference in semi-classical expansion of integer and half-integer spin particles.
Journal of High Energy Physics | 2015
Alireza Behtash; Erich Poppitz; Tin Sulejmanpasic; Mithat Unsal
A bstractWe show that compatibility of supersymmetry with exact semi-classics demands that in calculating multi-instanton amplitudes, the “separation” quasi-zeromode must be complexified and the integration cycles must be found by using complex gradient flow (or Picard-Lefschetz equations.) As a non-trivial application, we study N=2
Physics Letters B | 2015
Falk Bruckmann; Christof Gattringer; T. Kloiber; Tin Sulejmanpasic
arXiv: High Energy Physics - Theory | 2017
Alireza Behtash; Gerald V. Dunne; Tin Sulejmanpasic; Mithat Unsal; Thomas Schaefer
\mathcal{N}=2
Physical Review Letters | 2017
Tin Sulejmanpasic
Journal of High Energy Physics | 2015
Mohamed M. Anber; Tin Sulejmanpasic
extended supersymmetric quantum mechanics. Even though in this case supersymmetry is unbroken, the instanton-anti-instanton amplitude (naively calculated) seems to contribute to the ground state energy. We show, however, that the instanton-anti-instanton event consists of two parts: a fermion-correlated and a scalar-correlated event. Although both of these contributions are naively of the same sign and the latter is superficially higher order in the perturbative coupling, we show that the two contributions exactly cancel when they are evaluated on Lefschetz thimbles due to their relative Hidden Topological Angles (HTAs). This gives strong evidence that the semi-classical expansion using Lefschetz thimbles is not only a meaningful prescription for higher order semi-classics, but a necessary one. This deduction seems to be universal and applicable to both supersymmetric and non-supersymmetric theories. In conclusion we speculate that similar conspiracies are responsible for the non-formation of certain molecular contributions in theories where instantons have more than two fermionic zeromodes and do not contribute to the superpotential.
Computer Physics Communications | 2018
Tin Sulejmanpasic; Mithat Unsal
We derive dual representations for O(N) and CP(N-1) models on the lattice. In terms of the dual variables the partition sums have only real and positive contributions also at finite chemical potential. Thus the complex action problem of the conventional formulation is overcome and using the dual variables Monte Carlo simulations are possible at arbitrary chemical potential. Journal Reference: Phys. Lett. B749 (2015) 495-501
Communications in Mathematical Physics | 2018
Can Kozcaz; Mithat Unsal; Tin Sulejmanpasic; Yuya Tanizaki
We show that the semi-classical analysis of generic Euclidean path integrals necessarily requires complexification of the action and measure, and consideration of complex saddle solutions.We demonstrate that complex saddle points have a natural interpretation in terms of the Picard–Lefschetz theory. Motivated in part by the semi-classical expansion of QCD with adjoint matter on
Physical Review Letters | 2017
Tin Sulejmanpasic; Hui Shao; Anders W. Sandvik; Mithat Unsal
\mathbb{R}^3 \times S^1