1,721,081 research outputs found
Baryonic thermal fluctuations in finite temperature QCD
No full textWe show how, contrary to physical intuition, thermal fluctuations of physical states having a non-vanishing baryonic
number can be fully neglected in the thermodynamics of QCD at any physical temperature. We also discuss on the
consistency between our results and the CPT theorem. The last part of this article is devoted to comment some interesting
physical features which follow from this result
No-go theorem on spontaneous parity breaking revisited
No full textAn essential assumption in the Vafa and Witten's theorem on P and CT realization in vector-like theories concerns the existence of a free energy density in Euclidean space in the presence of any external hermitian symmetry breaking source. We show how this requires the previous assumption that the symmetry is realized in the vacuum. Even if the Vafa and Witten's conjecture is plausible, actually a theorem is still lacking
Parity and CT realization in QCD
No full textWe show that an essential assumption in the Vafa-Witten theorem on P and CT realization in
vectorlike theories, the existence of a free energy density in Euclidean space in the presence of any
external Hermitian symmetry breaking source, does not apply if the symmetry is spontaneously broken.
The assumption that the free energy density is well defined requires the previous assumption that the
symmetry is realized in the vacuum. Even if Vafa and Witten’s conjecture is plausible, actually a
theorem is still lacking
Method and apparatus for monitoring the personal exposure to static or quasi-static magnetic fields
No full textMethod for monitoring the exposure of one or more subjects to a magnetic
field in an environment, comprising the steps of:
- providing a spatial map of the components of said magnetic field in said environment;
- detecting, over time, a spatial position of said one or more subjects in said environment; and,
- for each detected position extracting from said map a corresponding value of the magnetic field associated with said detected position; and
- processing said values of magnetic field extracted over time to assess whether they exceed predetermined safety thresholds
“An Ex vivo Study of Skin Hydration Treatment by High Resolution Magnetic Resonance Imaging”
No full textApparato e metodo di imaging simultaneo tramite risonanza magnetica di spin elettronico e risonanza di spin nucleare
No full textE’ descritto un apparato di imaging (1) simultaneo di risonanza di spin elettronico e di risonanza di spin nucleare, comprendente:
- una prima bobina (L1a, L1b) ed un primo modulo di alimentazione (10) della prima bobina atto a pilotare la prima bobina (L1a, L1b) affinché questa produca un campo magnetico costante di osservazione per la rilevazione degli spin di elettroni e degli spin di nuclei di un campione in osservazione, il campo magnetico costante di osservazione avendo una intensità relativamente ridotta;
- una seconda bobina (L2) ed un secondo modulo di alimentazione (20) della seconda bobina (L2) atto a pilotare la seconda bobina (L2) affinché questa produca un campo magnetico pulsato atto a polarizzare i nuclei affinché questi si allineino lungo un vettore di induzione magnetica, detto campo magnetico pulsato avendo una intensità relativamente elevata
theta-vacuum - Phase transitions and/or symmetry breaking at theta = pi
No full textAssuming that a quantum field theory with a -vacuum term in the action shows non-trivial -dependence and provided that some reasonable properties of the probability distribution function of the order parameter hold, we argue that the theory either breaks spontaneously CP at or shows a singular behavior at some critical between 0 and . This result, which applies to any model with a pure imaginary contribution to the euclidean action consisting in a quantized charge coupled to a phase, as QCD, is illustrated with two simple examples; one of them intimately related to Witten's result on SU(N) in the large limit
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