336 research outputs found
Why Use a Hamilton Approach in QCD?
We discuss in the Hamiltonian frame work. We treat finite density
in the strong coupling regime. We present a parton-model inspired
regularisation scheme to treat the spectrum (-angles) and distribution
functions in . We suggest a Monte Carlo method to construct
low-dimensionasl effective Hamiltonians. Finally, we discuss improvement in
Hamiltonian .Comment: Proceedings of Hadrons and Strings, invited talk given by H.
Kr\"{o}ger; Text (LaTeX file), 3 Figures (ps file
Monte Carlo Hamiltonian from Stochastic Basis
In order to extend the recently proposed Monte Carlo Hamiltonian to many-body
systems, we suggest to concept of a stochastic basis. We apply it to the chain
of coupled anharmonic oscillators. We compute the spectrum of excited
states in a finite energy window and thermodynamical observables free energy,
average energy, entropy and specific heat in a finite temperature window.
Comparing the results of the Monte Carlo Hamiltonian with standard Lagrangian
lattice calculations, we find good agreement. However, the Monte Carlo
Hamiltonian results show less fluctuations under variation of temperature.Comment: revised version, new figures. Text (LaTeX), 4 Figs. (eps), style fil
Monte Carlo Hamiltonian
We suggest how to construct an effective low energy Hamiltonian via Monte
Carlo starting from a given action. We test it by computing thermodynamical
observables like average energy and specific heat for simple quantum systems.Comment: Contribution to Lattice'99 (Theoretical developments) Text (LaTeX
file) + 2 figures (ps files
Bound States and Critical Behavior of the Yukawa Potential
We investigate the bound states of the Yukawa potential , using different algorithms: solving the Schr\"odinger
equation numerically and our Monte Carlo Hamiltonian approach. There is a
critical , above which no bound state exists. We study the
relation between and for various angular momentum quantum
number , and find in atomic units, , with , ,
, and .Comment: 15 pages, 12 figures, 5 tables. Version to appear in Sciences in
China
New Method for Dynamical Fermions and Chiral-Symmetry Breaking
The reasons for the feasibility of the Microcanonical Fermionic Average
() approach to lattice gauge theory with dynamical fermions are discussed.
We then present a new exact algorithm, which is free from systematic errors and
convergent even in the chiral limit.Comment: 3 pages, DFTUZ 93/20, to appear in the Proceedings of Lattice 93,
Dalla
Improved Lattice Gauge Field Hamiltonian
Lepage's improvement scheme is a recent major progress in lattice ,
allowing to obtain continuum physics on very coarse lattices. Here we discuss
improvement in the Hamiltonian formulation, and we derive an improved
Hamiltonian from a lattice Lagrangian free of errors. We do this by
the transfer matrix method, but we also show that the alternative via Legendre
transformation gives identical results. We consider classical improvement,
tadpole improvement and also the structure of L{\"u}scher-Weisz improvement.
The resulting color-electric energy is an infinite series, which is expected to
be rapidly convergent. For the purpose of practical calculations, we construct
a simpler improved Hamiltonian, which includes only nearest-neighbor
interactions.Comment: 30 pages, LaTe
Some effects of different constitutive laws on simulating mitral valve dynamics with FSI
In this paper, three different constitutive laws for mitral leaflets and two laws for chordae tendineae are selected to study their effects on mitral valve dynamics with fluid-structure interaction. We first fit these three mitral leaflet constitutive laws and two chordae tendineae laws with experimental data. The fluid-structure interaction is implemented in an immersed boundary framework with finite element extension for solid, that is the hybrid immersed boundary/finite element(IB/FE) method. We specifically compare the fluid-structure results of different constitutive laws since fluid-structure interaction is the physiological loading environment. This allows us to look at the peak jet velocity, the closure regurgitation volume, and the orifice area. Our numerical results show that different constitutive laws can affect mitral valve dynamics, such as the transvalvular flow rate, closure regurgitation and the orifice area, while the differences in fiber strain and stress are insignificant because all leaflet constitutive laws are fitted to the same set of experimental data. In addition, when an exponential constitutive law of chordae tendineae is used, a lower closure regurgitation flow is observed compared to that of a linear material model. In conclusion, combining numerical dynamic simulations and static experimental tests, we are able to identify suitable constitutive laws for dynamic behaviour of mitral leaflets and chordae under physiological conditions
Unparticle Physics in the Moller Scattering
We investigate the virtual effects of vector unparticles in the Moller
scattering. We derive the analytic expression for scattering amplitudes with
unpolarized beams. We obtain 95% confidence level limits on the unparticle
couplings and with integrated luminosity of
and and 500 GeV energies. We show
that limits on are more sensitive than .Comment: 10 pages, 5 figures, 4 table
Renormalisation in Quantum Mechanics
We study a recently proposed quantum action depending on temperature. We
construct a renormalisation group equation describing the flow of action
parameters with temperature. At zero temperature the quantum action is obtained
analytically and is found free of higher time derivatives. It makes the quantum
action an ideal tool to investigate quantum chaos and quantum instantons.Comment: replaced version with new figs. Text (LaTeX), 3 Figs. (ps
Chiral phase transition in a lattice fermion--gauge--scalar model with U(1) gauge symmetry
The chiral phase transition induced by a charged scalar field is investigated
numerically in a lattice fermion-gauge-scalar model with U(1) gauge symmetry,
proposed recently as a model for dynamical fermion mass generation. For very
strong gauge coupling the transition is of second order and its scaling
properties are very similar to those of the Nambu--Jona-Lasinio model. However,
in the vicinity of the tricritical point at somewhat weaker coupling, where the
transition changes the order, the scaling behavior is different. Therefore it
is worthwhile to investigate the continuum limit of the model at this point.Comment: 20 pages, latex2e, 15 PostScript figures included, all files tared,
compressed and uudecode
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