116 research outputs found
Nontriviality of Abelian gauged Nambu-Jona-Lasinio models in four dimensions
We study a particular class of Abelian gauged Nambu-Jona-Lasinio models with
global U_L(N)xU_R(N) symmetry, where N is the number of fermion flavors. We
show, by treating the gauge interaction in the ladder approximation and
four-fermion interactions in the leading order of the 1/N expansion, that the
renormalization-group beta function of the U(1) gauge coupling has ultraviolet
stable fixed points for sufficiently large N. This implies the existence of a
nontrivial continuum limit.Comment: 44 pages, 10 figures, REVTeX, revised and corrected versio
Analytic structure of scalar composites in the symmetric phase of the gauged Nambu-Jona-Lasinio model
The gauged Nambu-Jona-Lasinio model in the quenched-ladder approximation has
non-trivial dynamics near a critical scaling region (critical curve) separating
a chiral symmetric and a dynamically chiral symmetry broken phase. Scalar and
pseudoscalar composites corresponding to the four-fermion interaction become
relevant degrees of freedom at short distances, which is reflected in the
appearance of a large anomalous dimension of the four-fermion operators. A
method is introduced for solving the Schwinger-Dyson equation for the Yukawa
vertex in specific kinematic regimes. This allows one to derive an analytic
expression for the scalar propagator, which is valid along the entire critical
curve. The mass and width of the scalar composites in the critical scaling
region are reexamined and the conformal phase transition at the critical gauge
coupling is discussed.Comment: final version to appear in Phys. Rev.
Modelling galaxy stellar mass evolution from z~0.8 to today
We apply the empirical method built for z=0 in the previous work of Wang et
al. to a higher redshift, to link galaxy stellar mass directly with its hosting
dark matter halo mass at z~0.8. The relation of the galaxy stellar mass and the
host halo mass M_infall is constrained by fitting both the stellar mass
function and the correlation functions at different stellar mass intervals of
the VVDS observation, where M_infall is the mass of the hosting halo at the
time when the galaxy was last the central galaxy. We find that for low mass
haloes, their residing central galaxies are less massive at high redshift than
those at low redshift. For high mass haloes, central galaxies in these haloes
at high redshift are a bit more massive than the galaxies at low redshift.
Satellite galaxies are less massive at earlier times, for any given mass of
hosting haloes. Fitting both the SDSS and VVDS observations simultaneously, we
also propose a unified model of the M_stars-M_infall relation, which describes
the evolution of central galaxy mass as a function of time. The stellar mass of
a satellite galaxy is determined by the same M_stars-M_infall relation of
central galaxies at the time when the galaxy is accreted. With these models, we
study the amount of galaxy stellar mass increased from z~0.8 to the present day
through galaxy mergers and star formation. Low mass galaxies gain their stellar
masses from z~0.8 to z=0 mainly through star formation. For galaxies of higher
mass, the increase of stellar mass solely through mergers from z=0.8 can make
the massive galaxies a factor ~2 larger than observed at z=0. We can also
predict stellar mass functions of redshifts up to z~3, and the results are
consistent with the latest observations.Comment: 12 pages, 10 figures, accepted for publication in MNRA
Salvarsan encephalopathie:een clinisch en histopathologisch onderzoek, pathophysiologische beschouwingen
De salvarsan-encephalopathie (S.E.) is een aandoening met een kenmerkend clinisch beeld en karakteristieke liquorafwijkingen. Ook de histopathologie heeft een eigen aard. De ziekte is zeldzaam bij de gewone routinebehandeling in normale omstandigheden, maar treedt bij de moderne massieve behandeling, in bijzondere omstandigheden als tijden van oorlog en bij bepaalde mensengroepen veel frequenter op (Hoofdstuk I). Aan de hand van 5 eigen gevallen, van welke 3 letaal verliepen en ter obductie kwamen, werd de aandoening bestudeerd en daarbij werd een poging gedaan om uit het histopathologisch beeld en uit de clinische gegevens, in verband met de literatuur, inzich te verkrijgen aangaande het mechanisme, waardoor de ziekte tot stand komt. ... Zie: Samenvattin
Anomalous dimensions of gauge-invariant amplitudes in massless effective gauge theories of strongly correlated systems
We use the radial gauge to calculate the recently proposed ansatz for the
physical electron propagator in such effective models of strongly correlated
electron systems as the theory of the pseudogap phase of the cuprates.
The results of our analysis help to settle the recent dispute about the sign
and the magnitude of the anomalous dimension which characterizes the gauge
invariant amplitude in question and set the stage for computing other, more
physically relevant, ones.Comment: Latex, 11 pages, no figure
- …