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Dissipation effects in mechanics and thermodynamics
With the discussion of three examples, we aim at clarifying the concept of
energy transfer associated with dissipation in mechanics and in thermodynamics.
The dissipation effects due to dissipative forces, such as the friction force
between solids or the drag force in motions in fluids, lead to an internal
energy increase of the system and/or to a heat transfer to the surrounding.
This heat flow is consistent with the second law, which states that the entropy
of the universe should increase when those forces are present because of the
irreversibility always associated with their actions. As far as mechanics is
concerned the effects of the dissipative forces are include in the Newton's
equations as impulses and pseudo-works.Comment: 18 pages, 3 figure
The Cabibbo-Kobayashi-Maskawa density matrices
The flavor changing charged currents of the weak sector of the Standard Model
are studied in the framework of a quantum statistical approach. The quantum
superposition of same-type quarks, generated by the Cabibbo-Kobayashi-Maskawa
matrix, is used to define three density matrices, one for each quark family.
The properties of such density matrices are analyzed, in particular, the
associated von Neumann entropy. It is proven that, due to the unitarity of the
Cabibbo-Kobayashi-Maskawa matrix, the quantum mixtures of quarks resulting from
the weak interaction do not increase entropy and, therefore, the violation of
CP and T symmetries cannot be related to the second law of thermodynamics.Comment: 3 page
Tricritical Point in Quantum Phase Transitions of the Coleman-Weinberg Model at Higgs Mass
The tricritical point, which separates first and second order phase
transitions in three-dimensional superconductors, is studied in the
four-dimensional Coleman-Weinberg model, and the similarities as well as the
differences with respect to the three-dimensional result are exhibited. The
position of the tricritical point in the Coleman-Weinberg model is derived and
found to be in agreement with the Thomas-Fermi approximation in the
three-dimensional Ginzburg-Landau theory. From this we deduce a special role of
the tricritical point for the Standard Model Higgs sector in the scope of the
latest experimental results, which suggests the unexpected relevance of
tricritical behavior in the electroweak interactions.Comment: 5 pages, 1 figure, published in Phys. Lett.
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