Speaker
Description
It is important to investigate the sign problem around the phase transition region, where the sign problem is serious. We investigate the model sign problem in the Polyakov loop extended Nambu-Jona-Lasinio (PNJL) model with repulsive vector-type interaction at finite temperature and density by using the path optimization method [1]. The Polyakov loop and the repulsive vector-type interaction have been known to cause the model sign problem in the path integral [2,3]. We have studied the sign problem in PNJL by using the path optimization method [2], in which the integration path in the complexified variable space is optimized to enhance the average phase factor [4,5]. Since the vector-type interaction is necessary to explain the repulsion at high density and also make the sign problem more serious, we now investigate the model including both the Polyakov loop and vector-type repulsion [1]. We find that the sign problem is more serious when we include both especially around the phase transition region. We demonstrate that complexification of the temporal gluon field and the vector-type auxiliary field together with optimizing the path can increase the average phase factor and we can control the model sign problem.
[1] K. Kashiwa, Y. Mori, A. Ohnishi, arXiv:1903.03679 [hep-ph].
[2] K. Kashiwa, Y. Mori, A. Ohnishi, Phys. Rev. D 99 (2019), 014033 [arXiv:1805.08940 [hep-ph]].
[3] Y. Mori, K. Kashiwa, A. Ohnishi, Phys. Lett. B 781 (2018), 688 [arXiv:1705.03646 [hep-lat]].
[4] Y. Mori, K. Kashiwa, A. Ohnishi, Phys. Rev. D 96 (2017), 111501(R [arXiv:1705.05605 [hep-lat]].
[5] Y. Mori, K. Kashiwa, A. Ohnishi, Prog. Theor. Exp. Phys. 2018 (2018), 023B04 [arXiv:1709.03208 [hep-lat]].
