QUENCHING OF MACROSCOPIC QUANTUM COHERENCE AND MACROSCOPIC FERMI-PARTICLE CONFIGURATIONS

Starting from the coherent state representation of the evolution opera tor with the help of the path-integral, we derive a formula for the lo w-lying levels E = epsilon(0) - 2 Delta epsilon cos(s + xi)pi of a qua ntum spin system. The quenching of macroscopic quantum coherence is un derstood as the vanishing of cos(s + xi)pi in disageement with the sup pression of tunneling (i.e. Delta epsilon = 0) as claimed in the liter ature. A new configuration called the macroscopic Fermi-particle is su ggested by the nature of its wave function. The tunneling (2 Delta eps ilon/pi) does not vanish, not for integer spin s nor for a half-intege r value of s, and is calculated explicitly (for the position dependent mass) up to the one-loop approximation.