1,721,043 research outputs found
Low Q 2 boundary conditions for DGLAP equations dictated by quantum statistical mechanics
Full text linkWe discuss the role of quantum statistical mechanics in the description of the parton distribution functions in the proton. It provides the low Q 2 boundary conditions for DGLAP equations in terms of Fermi–Dirac and Bose–Einstein functions of the fractional momentum variable x. The successful comparison with experimental data on both the unpolarised and polarised deep inelastic structure functions is reviewed. We argue that the statistical approach for the nucleon parton distributions functions has the nice feature that the free model parameters are fixed from data with high statistics and small systematic uncertainties, providing a strong constraint on the information not supplied by the experiments
Energy-charge correlation in the π+π-π0 decay of KL and of tagged neutral kaons
No full textWe relate the asymmetries in the charged pions energy in the decay into π+π-π0 of KL and of the tagged neutral kaons. The former asymmetry is a given combination of {Mathematical expression}, and üε'ü. Moreover, the non-violating CP asymmetry allows a test for theχPT predictions within the Zel'dovich approach for the final state interaction. © 1995 Springer-Verlag
Spontaneously broken SU(5) symmetries and 1-loop effects in the early universe
No full text?his paper studies the 1-loop eEective potential and spontaneous-spmetrybreaking
pattern for SU(5) gauge theory in de Sitter spacetime. Curvature effects
modify the flat-space effective potential by means of a very complicated special function
previously derived in the literature. An algebraic technique already developed by Buccella
ef al to study spontaneous symmelry breaking of SU(n) for renormalikable polynomial
potentials is here generalized, for SU(5), to the much more difficult case of a de Sitler
background. A detailed algebraic and numerical analysis provides a better derivation of
the stabilily of the exlrema in the maximal subgroups SU(4) x U(l), SU(3) x S U ( 2 ) x
U( l ) , S U ( 3) X U ( 1 ) X U ( 1 ) XR311, SU( 2) x S U (2 ) x U ( l ) x U ( 1 ) x R2211 , w h e r e
R311 and R2211 discrete symmetries select particular directions in the corresponding
two-dimensional strata. One thus obtains a deeper understanding of the result, previously
found wilh a different numerical analysis, predicting the slide of the inflationary universe
into either the SU(3) x SU(2) x U(I) or SU(4) x U(1) extremum. Interestingly,
using this approach, one can easily generalize all previous results to a more complete
SU(5) tree-level potential also containing cubic terms
Pane di festa. Le cuddure a Roccafiorita e Limina
No full textIl capitolo analizza gli usi rituali delle cuddure, dolce tipico della Valle d'Agrò, e ne indaga le valenze simboliche legate al ciclo di morte-rinascita proprio delle festività pasquali
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