Gluonic phases, vector condensates, and exotic hadrons in dense QCD

Abstract

We study the dynamics in phases with vector condensates of gluons (gluonic phases) in dense two-flavor quark matter. These phases yield an example of dynamics in which the Higgs mechanism is provided by condensates of gauge (or gauge plus scalar) fields. Because vacuum expectation values of spatial components of vector fields break the rotational symmetry, it is natural to have a spontaneous breakdown both of external and internal symmetries in this case. In particular, by using the Ginzburg-Landau approach, we establish the existence of a gluonic phase with both the rotational symmetry and the electromagnetic U (1) being spontaneously broken. In other words, this phase describes an anisotropic medium in which the color and electric superconductivities coexist. It is shown that this phase corresponds to a minimum of the Ginzburg-Landau potential and, unlike the two-flavor superconducting (2SC) phase, it does not suffer from the chromomagnetic instability. The dual (confinement) description of its dynamics is developed and it is shown that there are light exotic vector hadrons in the spectrum, some of which condense. Because most of the initial symmetries in this system are spontaneously broken, its dynamics is very rich.

Extensive study of phase diagram for charge-neutral homogeneous quark matter affected by dynamical chiral condensation: unified picture for thermal unpairing transitions from weak to strong coupling

“…These include; (i) exploring a possibility of the mixed phase [15] along the line suggested earlier [54][55][56], (ii) the baryon current generation [16], (iii) examining the crystalline pairing phases [57] taking the neutrality constraints into account [17,18], (iv) investigating a possible secondary gap formation [19], (v) the gluon condensation in the g2SC [20], and (vi) an inhomogeneous (p-wave) Kaon condensate [21]. Examining all these possibilities or searching for a more stable ground state as well as exploring a nature of the gluonic instability in the gapless phases is now one of central problems in QCD.…”

“…(20) and some matrix elements in these bases [36] without recourse to numerical derivatives done in [11,23,29]. The charge neutrality constraints can be also expressed in terms of the matrix elements in the basis composed of these eigen-spinors.…”

“…The gCFL phase has been extensively studied and claimed to be the most promising candidate of next phase down in density at vanishing temperature [11] and is also known to lead an interesting astrophysical consequence on the cooling history of an aged compact star [12]. It should be, however, noted here that the gapless phases are usually accompanied by some transverse gluonic modes with imaginary Meissner mass at low temperature [13,14], indicating the existence of more stable exotic states [15][16][17][18][19][20][21]. Although the resolution of the instability or finding the possible new stable state is now one of the central issues in this field, we won't deal with this problem; nevertheless we will give some suggestions to possible resolution on the basis of the results obtained in this work.…”

Higgs instability in gapless superfluidity/superconductivity

“…Recent studies have demonstrated that this type of instability is related to the local phase fluctuation of the superconducting order parameter, i.e., the Nambu-Goldstone boson fields [9,10,11,12]. This type of instability induces the formation of the single-planewave FF-like state [13,14,15,16,17].…”

“…Recent studies have demonstrated that this type of instability is related to the local phase fluctuation of the superconducting order parameter, i.e., the Nambu-Goldstone boson fields [9,10,11,12]. This type of instability induces the formation of the single-planewave FF-like state [13,14,15,16,17].The imbalanced cold atom systems such as the 40 K and 6 Li offer an intriguing experimental opportunity to understand the pair breaking states. However, recent experiments [18] on these systems did not show explicit evidence of the BP state or the LOFF state, rather they produced strong evidence of the phase separation at moderate mismatch.…”