Unusual condensates in quark and atomic systems†

^†Lectures delivered at 8th Moscow school of Physics (33rd ITEP Winter School of Physics).

Abstract

In these lectures, we discuss condensates which are formed in quark matter when it is squeezed and in a gas of fermionic atoms when it is cooled. The behavior of these two seemingly very different systems reveals striking simularities. In particular, in both systems the Bose–Einstein condensate to Bardeen–Cooper–Schrieffer (BEC–BCS) crossover takes place.

Keywords:

• Quark systems
• Atomic systems
• BEC–BCS Crossover
• Condensates

Notes

^†Lectures delivered at 8th Moscow school of Physics (33rd ITEP Winter School of Physics).

Compact electron pairs were introduced [20] in an attempt to explain superconductivity couple of years before the BCS theory was formulated. Sometimes compact molecular-like states are called Schafroth pairs.

Close to the Fermi surface this attraction overcomes Coulomb repulsion [21].

We stress that is true only in the BCS regime.

The rigorous definition of the scattering length for the contact interaction entering into equation (3) may be found in [30,31].

This value is obtained according to , but it is close to the result for free degenerate quarks .

Recall that in the BCS theory [26].