1,721,024 research outputs found
Three-manifold invariants and their relation with the fundamental group
No full textWe consider the 3-manifold invariant I(M) which is defined by means of
the Chern-Simons quantum field theory and which coincides with the
Reshetikhin-Turaev invariant. We present some arguments and numerical
results supporting the conjecture that for nonvanishing I(M), the
absolute value \I(M)\ only depends on the fundamental group pi(1)(M) of
the manifold M. For lens spaces, the conjecture is proved when the gauge
group is SU(2). In the case in which the gauge group is SU(3), we
present numerical computations confirming the conjecture
Three-dimensional topology and Verlinde formulas
No full textWe study the properties of the gauge invariant observables of the
three-dimensional Chern-Simons field theory; it is shown that the algebra
structure determined by the observables is isomorphic with the fusion
rules of two-dimensional conformal theories. In the colour state space
of the link components, a projective representation of the modular group
is defined. The relations satisfied by the S matrix of the conformal
models admit an interpretation in terms of three-dimensional topology;
we describe the topological origin of these relations
Reduced tensor algebra in SU(3) Chern-Simons field theory
No full textWe consider the non-Abelian SU(3) Chern-Simons field theory defined in
R3 and S3. The reconstruction theorems for the vacuum expectation
values of the Wilson line operators are proved. We give in particular
the general expressions for the values of the unknot and of the Hopf
link. The physical consequences of the quantization of the coupling
constant are studied in detail. The structure of the resulting reduced
tensor algebra is derived
SU(3) Chern-Simons field theory in three-manifolds
No full textWe present the solution of the non-Abelian SU (3) Chern-Simons field
theory defined in a generic three-manifold which is closed, connected
and orientable. The surgery rules, which permit us to solve the theory,
are derived and several examples of vacuum expectation values of Wilson
line operators are computed. The three-manifold invariant associated
with the non-Abelian SU (3) Chern-Simons model is defined and its values
are computed for various three-manifolds
Numerical simulation to improve individual cylinder AFR control in a 4 cylinder s.i. engine
No full textDynamical cosmological constant
Full text linkThe dynamical realization of the equation of state p & thorn; rho = 0 is studied. A nonpathological dynamics for the perturbations of such a system mimicking a dynamical cosmological constant (DCC) requires to go beyond the perfect fluid paradigm. It is shown that an anisotropic stress must be always present. The Hamiltonian of the system in isolation resembles the one of a Pais-Uhlenbeck oscillator and linear stability requires that it cannot be positive definite. The dynamics of linear cosmological perturbations in a DCC dominated Universe is studied in detail showing that when DCC is minimally coupled to gravity no dramatic instability is present. In contrast to what happens in a cosmological constant dominated Universe, the nonrelativistic matter contrast is no longer constant and exhibits an oscillator behavior at small scales while it grows weakly at large scales. In the gravitational waves sector, at small scales, the amplitude is still suppressed as the inverse power of the scale factor while it grows logarithmically at large scales. Also the vector modes propagate, though no growing mode is found
Development of a new mean value model for the analysis of turbolag phenomena in automotive diesel engines
No full textWeak massive gravity
No full textWe find a new class of theories of massive gravity with five propagating degrees of freedom where only rotations are preserved. Our results are based on a nonperturbative and background-independent Hamiltonian analysis. In these theories the weak field approximation is well behaved and the static gravitational potential is typically screened a` la Yukawa at large distances, while at short distances no van Dam-Veltman-Zakharov discontinuity is found and there is no need to rely on nonlinear effects to pass the solar system tests. The effective field theory analysis shows that the ultraviolet cutoff is ðmMPlÞ1=2 ’ 1="m, the highest possible. Thus, these theories can be studied in the weak-field regime at all the phenomenologically interesting scales and are candidates for a calculable large-distance modified gravity
A Numerical Contribution to the Improvement of Individual Cylinder AFR Control in a 4 Cylinder S.I. Engine
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