35 research outputs found
Novel glassy behavior in a ferromagnetic p-spin model
Recent work has suggested the existence of glassy behavior in a ferromagnetic
model with a four-spin interaction. Motivated by these findings, we have
studied the dynamics of this model using Monte Carlo simulations with
particular attention being paid to two-time quantities. We find that the system
shares many features in common with glass forming liquids. In particular, the
model exhibits: (i) a very long-lived metastable state, (ii) autocorrelation
functions that show stretched exponential relaxation, (iii) a non-equilibrium
timescale that appears to diverge at a well defined temperature, and (iv) low
temperature aging behaviour characteristic of glasses.Comment: 6 pages, 5 figure
Renormalization of composite operators
The blocked composite operators are defined in the one-component Euclidean
scalar field theory, and shown to generate a linear transformation of the
operators, the operator mixing. This transformation allows us to introduce the
parallel transport of the operators along the RG trajectory. The connection on
this one-dimensional manifold governs the scale evolution of the operator
mixing. It is shown that the solution of the eigenvalue problem of the
connection gives the various scaling regimes and the relevant operators there.
The relation to perturbative renormalization is also discussed in the framework
of the theory in dimension .Comment: 24 pages, revtex (accepted by Phys. Rev. D), changes in introduction
and summar
Current correlators to all orders in the quark masses
The contributions to the coefficient functions of the quark and the mixed
quark-gluon condensate to mesonic correlators are calculated for the first time
to all orders in the quark masses, and to lowest order in the strong coupling
constant. Existing results on the coefficient functions of the unit operator
and the gluon condensate are reviewed. The proper factorization of short- and
long-distance contributions in the operator product expansion is discussed in
detail. It is found that to accomplish this task rigorously the operator
product expansion has to be performed in terms of non-normal-ordered
condensates. The resulting coefficient functions are improved with the help of
the renormalization group. The scale invariant combination of dimension 5
operators, including mixing with the mass operator, which is needed for the
renormalization group improvement, is calculated in the leading order.Comment: 24 pages, LateX file, TUM-T31-21/92, 1 postscript file include
Radiative Decays, Nonet Symmetry and SU(3) Breaking
We re-examine the problem of simultaneously describing in a consistent way
all radiative and leptonic decays of light mesons (V -> P gamma, P -> V gamma,
P -> gamma gamma, V -> e^+ e^-). For this purpose, we rely on the Hidden Local
Symmetry model in both its anomalous and non--anomalous sectors. We show that
the SU(3) symmetry breaking scheme proposed by Bando, Kugo and Yamawaki,
supplemented with nonet symmetry breaking in the pseudoscalar sector, allows
one to reach a nice agreement with all data, except for the K^{*+/-} radiative
decay. An extension of this breaking pattern allows one to account for this
particular decay mode too. Considered together, the whole set of radiative
decays provides a pseudoscalar mixing angle theta_P ~ -11^o and a value for
theta_V which is ~ 3^o from that of ideal mixing. We also show that it is
impossible, in a practical sense, to disentangle the effects of nonet symmetry
breaking and those of glue inside the eta', using only light meson decays.Comment: 36 pages. Published versio
Rif1 Controls DNA Replication Timing in Yeast through the PP1 Phosphatase Glc7
The Rif1 protein, originally identified as a telomere-binding factor in yeast, has recently been implicated in DNA replication control from yeast to metazoans. Here, we show that budding yeast Rif1 protein inhibits activation of prereplication complexes (pre-RCs). This inhibitory function requires two N-terminal motifs, RVxF and SILK, associated with recruitment of PP1 phosphatase (Glc7). In G1 phase, we show both that Glc7 interacts with Rif1 in an RVxF/SILK-dependent manner and that two proteins implicated in pre-RC activation, Mcm4 and Sld3, display increased Dbf4-dependent kinase (DDK) phosphorylation in rif1 mutants. Rif1 also interacts with Dbf4 in yeast two-hybrid assays, further implicating this protein in direct modulation of pre-RC activation through the DDK. Finally, we demonstrate Rif1 RVxF/SILK motif-dependent recruitment of Glc7 to telomeres and earlier replication of these regions in cells where the motifs are mutated. Our data thus link Rif1 to negative regulation of replication origin firing through recruitment of the Glc7 phosphatase