Pairing Phase Transitions of Matter under Rotation

Abstract

The phases and properties of matter under global rotation have attracted much interest recently. In this paper we investigate the pairing phenomena in a system of fermions under the presence of rotation. We find that there is a generic suppression effect on pairing states with zero angular momentum. We demonstrate this effect with the chiral condensation and the color superconductivity in hot dense QCD matter as explicit examples. In the case of chiral condensation, a new phase diagram in the temperature-rotation parameter space is found, with a nontrivial critical point.Introduction.-The phases and properties of matter can become highly nontrivial under rotation, and have attracted a lot of interest recently. Such studies bear particular relevance for the strongly interacting matter of Quantum Chromodynamics (QCD). For example, astrophysical objects like neutron stars, made of dense QCD matter, can be rapidly spinning [1,2]. In relativistic heavy ion collision experiments, the typical collision events are off-central and the created QCD matter will carry a nonzero angular momentum on the order of 10 4 ∼ 10 5 with local angular velocity in the range 0.01 ∼ 0.1GeV [3][4][5][6][7][8]. There has also been impressive progress to study the rotating QCD matter using lattice gauge theory simulations [9].In rotating matter, many interesting transport phenomena could occur. For example, fluid rotation can induce anomalous transport processes in a system of chiral fermions, such as the chiral vortical effect [10][11][12] and chiral vortical wave [13]. These can lead to measurable experimental signals (see e.g. reviews in [14,15]). In such anomalous transport, it is found that the fluid rotation plays a very analogous role to a magnetic field. Indeed there appears to be interesting similarity between the chiral vortical effect and the chiral magnetic effect [10,16], as well as between the chiral vortical wave and the chiral magnetic wave [17,18].Apart from transport properties, it is of significant interest to explore the effects of rotation on the phase transitions of matter in both relativistic and non-relativistic cases. It is well known that a magnetic field can bring interesting effects on the thermodynamics and phase diagram of e.g. QCD matter [19][20][21][22][23][24], such as the magnetic catalysis and inverse catalysis (see reviews in [25,26]) on the chiral condensation. Given the close analogy between rotation and magnetic field, it is tempting to ask how the rotation could influence phase transitions. In this paper, we investigate the pairing phenomena in a system of fermions under rotation. We find a generic suppression effect on pairing states with zero angular momentum,

Strongly interacting matter under rotation

“…It is conceivable that similar phase transition behaviors under rotation would also occur in other dynamical models for studying chiral condensate. In [12] we also studied the diquark condensate case. As our analysis in above the rotational suppression would emerge again in that system.…”

“…In the following, we quantitatively demonstrate this effect in the Nambu-Jona-Lasinio model for the chiral condensate (of quark-anti-quark pairing states with L = S = 1 but J = 0). And the diquark condensate (of quarkquark pairing state with L = S = 0) case could be referred to [12].…”

“…With the results we would see the vorticity is so remarkable that we could not simply neglect its impact on the phase transition and chiral transport. Hence we discuss the rotational polarization effects for quark pairings, which would change the chiral restoration and color superconductivity critical behaviors [12]. In chiral restored phase the vorticity would also induce two anomalous chiral transport relations for the left and right-handed quarks respectively [13,14].…”

“…There has also been impressive progress to study the rotating QCD matter using lattice gauge theory simulations [11]. Both first principle calculations and model studies suggest that vorticity would drive the phase transition [12] and anomalous transport [13][14][15]. In the following we will first simulate the collisions to extract the vorticity with AMPT model in the particle scenario [10].…”

Vortical susceptibility of finite-density QCD matter

“…While the alignment of quark spins by rotation in a chirally symmetric phase has been extensively discussed in the literature [3,[21][22][23][24][25][26][27][28] (see [29] for a recent review), a priori…”