Blue quark

It is instructive to start with the excitation spectrum in the case of the ordinary 2SC phase when dfi = 0. With the conventional choice of the gap pointing in the anti-blue direction in color space, the blue quarks are not affected by the pairing dynamics, and the other four quasi-particle excitations are linear superpositions of ur>g and dr(J quarks and holes. The quasi-particle is nearly identical with a quark at large momenta and with a hole at small momenta. We represent the quasi-particle in the form of Q(quark, hole), then the four quasiparticles can be represented explicitly as Q(ur,dg), Q(ug, dr), Q(dr,ug) and Q(dg,ur). When S/i = 0, the four quasi-particles are degenerate, and have a common gap A. 

The resulting phase diagram is shown in Fig. 5. It includes a 2-flavor color superconductivity (2SC) phase for which quarks of one color, say blue, remain unpaired. The color-flavor locking (CFL) phase [25] requires approximate SU(3) flavor symmetry and can be excluded from our discussion since strange quarks remain confined up to the highest densities occuring in a compact star configuration [24],... 

The concept of defects came about from crystallography. Defects are dismptions of ideal crystal lattice such as vacancies (point defects) or dislocations (linear defects). In numerous liquid crystalline phases, there is variety of defects and many of them are not observed in the solid crystals. A study of defects in liquid crystals is very important from both the academic and practical points of view [7,8]. Defects in liquid crystals are very useful for (i) identification of different phases by microscopic observation of the characteristic defects (ii) study of the elastic properties by observation of defect interactions (iii) understanding of the three-dimensional periodic structures (e.g., the blue phase in cholesterics) using a new concept of lattices of defects (iv) modelling of fundamental physical phenomena such as magnetic monopoles, interaction of quarks, etc. In the optical technology, defects usually play the detrimental role examples are defect walls in the twist nematic cells, shock instability in ferroelectric smectics, Grandjean disclinations in cholesteric cells used in dye microlasers, etc. However, more recently, defect structures find their applications in three-dimensional photonic crystals (e.g. blue phases), the bistable displays and smart memory cards. 

Quarks and gluons have quantum numbers called color. The primary, basic colors maybe called red, green, and blue. Of course, these colors have no relation to ordinary, real colors. The quarks interact strongly by color exchange, which means that the quanta of the strong interaction, the gluons, are colored objects. All bound states of quarks observed in nature are colorless or white. Leptons do not have color quantum numbers. 

Fig. 4.2 Transverse momentum (left) and pseudorapidity (right) distribution of h quarks originating from proton-proton collisions at a center-of-mass energy of = 1 TeV. The inclusive distribution is shown in blue, the gmen distribution corresponds to b quarks that decay semileptonically into muons and the md one describes quarks whose decay produce muons within the visible kinematic range (pj > 5GeV and —2.1 < 77 < 2.1)...

Fig. 8.3 (Color online) The formation of atomic nuclei, started instants after the big bang, as the universe cooled, when the fundamental particles called free quarks (a) condensed into protons and neutrons (b). Protons red) and neutrons blue) paired off to form deuterons (deuterium nuclei), but because the former outnumber the latter, most of the protons remained alone and became hydrogen nuclei (c). Almost all deuterium combined to form helium nuclei (d). Therefore there remained only little deuterium to be detected today...

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