2,920 research outputs found
Critical Behaviour of the 3d Gross-Neveu and Higgs-Yukawa Models
We measure the critical exponents of the three dimensional Gross-Neveu model
with two four-component fermions. The exponents are inferred from the scaling
behaviour of observables on different lattice sizes. We also calculate the
exponents, through a second order epsilon-expansion around 4d, for the three
dimensional Higgs-Yukawa model, which is expected to be in the same
universality class and we find that the exponents agree. We conclude that the
equivalence of the two models remains valid in 3d at fixed small N_f values.Comment: 14 Latex pages 8 PSfigures included at the
end,BI-TP-93/31,AZPH-TH/93-19,SPhT 93/0
Three dimensional finite temperature SU(3) gauge theory in the confined region and the string picture
We determine the correlation between Polyakov loops in three dimensional
SU(3) gauge theory in the confined region at finite temperature. For this
purpose we perform lattice calculations for the number of steps in the
temperature direction equal to six. This is expected to be in the scaling
region of the lattice theory. We compare the results to the bosonic string
model. The agreement is very good for temperatures T<0.7T_c, where T_c is the
critical temperature. In the region 0.7T_c<T<T_c we enter the critical region,
where the critical properties of the correlations are fixed by universality to
be those of the two dimensional three state Potts model. Nevertheless, by
calculating the critical lattice coupling, we show that the ratio of the
critical temperature to the square root of the zero temperature string tension,
where the latter is taken from the literature, remains very near to the string
model prediction.Comment: 11 pages, 1 figure, 1 tabl
Random matrix model for QCD_3 staggered fermions
We show that the lowest part of the eigenvalue density of the staggered
fermion operator in lattice QCD_3 at small lattice coupling constant beta has
exactly the same shape as in QCD_4. This observation is quite surprising, since
universal properties of the QCD_3 Dirac operator are expected to be described
by a non-chiral matrix model. We show that this effect is related to the
specific nature of the staggered fermion discretization and that the eigenvalue
density evolves towards the non-chiral random matrix prediction when beta is
increased and the continuum limit is approached. We propose a two-matrix model
with one free parameter which interpolates between the two limits and very well
mimics the pattern of evolution with beta of the eigenvalue density of the
staggered fermion operator in QCD_3.Comment: 8 pages 4 figure
Albert algebras over Z and other rings
Albert algebras, a specific kind of Jordan algebra, are naturally
distinguished objects among commutative non-associative algebras and also arise
naturally in the context of simple affine group schemes of type , ,
or . We study these objects over an arbitrary base ring , with
particular attention to the case of the integers. We prove in this generality
results previously in the literature in the special case where is a field
of characteristic different from 2 and 3.Comment: v2: section 12 on number of generators is new, Theorem 13.5 now holds
for semi-local rings (and even a somewhat wider class
Voltage-Controlled Superconducting Quantum Bus
We demonstrate the ability of an epitaxial semiconductor-superconductor
nanowire to serve as a field-effect switch to tune a superconducting cavity.
Two superconducting gatemon qubits are coupled to the cavity, which acts as a
quantum bus. Using a gate voltage to control the superconducting switch yields
up to a factor of 8 change in qubit-qubit coupling between the on and off
states without detrimental effect on qubit coherence. High-bandwidth operation
of the coupling switch on nanosecond timescales degrades qubit coherence
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