Eur. Phys. J. C (2017) 77: 69
https://doi.org/10.1140/epjc/s10052-017-4643-x

Regular Article - Theoretical Physics

Split degenerate states and stable pp phases from holography

¹ Kunming University of Science and Technology, Kunming, 650500, China
² Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing, 100190, China
³ Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Synergetic Innovation Center for Quantum Effects and Applications, Department of Physics, Hunan Normal University, Changsha, 410081, Hunan, China
⁴ College of Physics Science and Technology, Yangzhou University, Yangzhou, 225009, Jiangsu, China
⁵ Department of Physics, National Central University, Chungli, 32001, Taiwan

^* e-mail: niezy@kmust.edu.cn

Received: 8 December 2016
Accepted: 23 January 2017
Published online: 4 February 2017

Abstract

In this paper, we investigate the pp superfluid phases in the complex vector field holographic p-wave model. We find that in the probe limit, the pp phase and the p-wave phase are equally stable, hence the p and ip orders can be mixed with an arbitrary ratio to form more general pp phases, which are also equally stable with the p-wave and pp phases. As a result, the system possesses a degenerate thermal state in the superfluid region. We further study the case on considering the back-reaction on the metric, and we find that the degenerate ground states will be separated into p-wave and pp phases, and the p-wave phase is more stable. Finally, due to the different critical temperature of the zeroth order phase transitions from p-wave and pp phases to the normal phase, there is a temperature region where the pp phase exists but the p-wave phase does not. In this region we find the stable holographic pp phase for the first time.