Finite density two color chiral perturbation theory revisited

Abstract

We revisit two-color, two-flavor chiral perturbation theory at finite isospin and baryon density. We investigate the phase diagram obtained varying the isospin and the baryon chemical potentials, focusing on the phase transition occurring when the two chemical potentials are equal and exceed the pion mass (which is degenerate with the diquark mass). In this case, there is a change in the order parameter of the theory that does not lend itself to the standard picture of first order transitions. We explore this phase transition both within a Ginzburg-Landau framework valid in a limited parameter space and then by inspecting the full chiral Lagrangian in all the accessible parameter space. Across the phase transition between the two broken phases the order parameter becomes an SU (2) doublet, with the ground state fixing the expectation value of the sum of the magnitude squared of the pion and the diquark fields. Furthermore, we find that the Lagrangian at equal chemical potentials is invariant under global SU (2) transformations and construct the effective Lagrangian of the three Goldstone degrees of freedom by integrating out the radial fluctuations.

Magnetic vortex lattices in finite isospin chiral perturbation theory

“…The χPT results are model independent and valid if the parameters involved (x) satisfy x Λ hadr ∼ 4π f π , where x can be momentum (p), mass (m π ), isospin chemical potential (µ I ), temperature (T ) or an external magnetic field ( √ eH). Similar studies at finite isospin and finite baryon densities have been performed in QCD Email address: adhika1@stolaf.edu (Prabal Adhikari) with different representations (of quarks) and number of colors [11] including two-color, two-flavor, which possess a rich phase structure [12] with both pion and diquark condensation and an unusual first order transition [13] and QCD with arbitrary number of quarks in the adjoint representation. Furthermore, finite isospin QCD has been extended to asymptotically large isospin chemical potentials [14], where χPT is not valid but analytical studies are still possible due to asymptotic freedom and the ability to find the BCS gap similar to large baryon chemical potentials, where QCD exhibits color-flavor-locking [15,16].…”

First Direct Search for Inelastic Boosted Dark Matter with COSINE-100

“…For COSINE-100, we use the specific layout of the detector components combined with the predicted topology of iBDM interactions to identify candidate iBDM events. COSINE-100 [27] consists of a 106 kg array of eight ultra-pure NaI(Tl) crystals each coupled to two photomultiplier tubes (PMTs). The crystals are immersed in an active veto detector composed of 2,200 L of linear alkylbenzene (LAB)-based liquid scintillator (LS) [35].…”

“…In this Letter, we report the first search for inelastic boosted dark matter (iBDM) in a terrestrial detector, performed with the COSINE-100. The main purpose of the COSINE-100 experiment [27,28] is to confirm or refute the long-debated claim by the DAMA collaboration…”

Two-colour QCD phases and the topology at low temperature and high density

“…Consistency of the µ and j dependence of various quantities with the mean-field prediction by the chiral perturbation theory (ChPT) [15,25,26,28] was examined in detail. Since the ChPT is applicable at sufficiently small µ, it can at most predict the appearance of a diquark Bose-Einstein condensed (BEC) phase around µ ∼ m PS /2 and the µ dependence of the diquark and chiral condensates.…”