474 research outputs found
Do Wilson Fermions Induce an Adjoint Gauge Coupling?
Expansions of the Wilson determinant in lattice QCD with quarks produce gauge
action terms which shift the coupling constant of the fundamental
representation plaquette action and induce an adjoint representation plaquette
action. We study the magnitude of these induced couplings with two flavors of
Wilson fermions. We utilize a microcanonical demon method, which allows us to
measure the induced couplings directly from gauge configurations generated by
full fermionic simulations.Comment: 3 pages postscript, proceedings for LATTICE '9
Numerical Study of Wave Propagation in Uniaxially Anisotropic Lorentzian Backward Wave Slabs
The propagation and refraction of a cylindrical wave created by a line
current through a slab of backward wave medium, also called left-handed medium,
is numerically studied with FDTD. The slab is assumed to be uniaxially
anisotropic. Several sets of constitutive parameters are considered and
comparisons with theoretical results are made. Electric field distributions are
studied inside and behind the slab. It is found that the shape of the
wavefronts and the regions of real and complex wave vectors are in agreement
with theoretical results.Comment: 6 pages, figure
High Temperature 3D QCD: Dimensional Reduction at Work
We investigate the three-dimensional SU(3) gauge theory at finite temperature
in the framework of dimensional reduction. The large scale properties of this
theory are expected to be conceptually more complicated than in four
dimensions. The dimensionally reduced action is computed in closed analytical
form. The resulting effective two-dimensional theory is studied numerically
both in the electric and magnetic sector. We find that dimensional reduction
works excellently down to temperatures of 1.5 times the deconfinement phase
transition temperature and even on rather short length scales. We obtain strong
evidence that for , even at high temperature the colour averaged
potential is represented by the exchange of a single state, at variance with
the usual Debye screening picture involving a pair of electric gluons.Comment: 27 page
Low Space External Memory Construction of the Succinct Permuted Longest Common Prefix Array
The longest common prefix (LCP) array is a versatile auxiliary data structure
in indexed string matching. It can be used to speed up searching using the
suffix array (SA) and provides an implicit representation of the topology of an
underlying suffix tree. The LCP array of a string of length can be
represented as an array of length words, or, in the presence of the SA, as
a bit vector of bits plus asymptotically negligible support data
structures. External memory construction algorithms for the LCP array have been
proposed, but those proposed so far have a space requirement of words
(i.e. bits) in external memory. This space requirement is in some
practical cases prohibitively expensive. We present an external memory
algorithm for constructing the bit version of the LCP array which uses
bits of additional space in external memory when given a
(compressed) BWT with alphabet size and a sampled inverse suffix array
at sampling rate . This is often a significant space gain in
practice where is usually much smaller than or even constant. We
also consider the case of computing succinct LCP arrays for circular strings
3d physics and the electroweak phase transition: a framework for lattice Monte Carlo analysis
We discuss a framework relying on both perturbative and non-perturbative
lattice computations which will be able to reliably determine the parameters of
the EW phase transition. A motivation for the use of 3d effective theory in the
lattice simulations, rather than the complete 4d one, is provided. We introduce
and compute on the 2-loop level a number of gauge-invariant order parameters --
condensates, which can be measured with high accuracy in MC simulations. The
relation between MSbar and lattice condensates is found, together with the
relation between lattice couplings and continuum parameters (the constant
physics curves). These relations are exact in the continuum limit.Comment: 50 pages, uuencoded compressed postscript fil
Natural neutrino sector in a 331-model with Froggatt-Nielsen mechanism
The extensions of the Standard Model based on the SU(3)c × SU(3)L × U(1)X gauge group (331-models) have been advocated to explain the number of fermion families in nature. It has been recently shown that the Froggatt-Nielsen mechanism, a popular way to explain the mass hierarchy of the charged fermions, can be incorporated into the 331-setting in an economical fashion (FN331). In this work we extend the FN331-model to include three right-handed neutrino singlets. We show that the seesaw mechanism is realized in this model. The scale of the seesaw mechanism is near the SU(3)L × U(1)X-breaking scale. The model we present here simultaneously explains the mass hierarchy of all the fermions, including neutrinos, and the number of families. © 2020, The Author(s).Peer reviewe
Density Functional Theory of Multicomponent Quantum Dots
Quantum dots with conduction electrons or holes originating from several
bands are considered. We assume the particles are confined in a harmonic
potential and assume the electrons (or holes) belonging to different bands to
be different types of fermions with isotropic effective masses. The density
functional method with the local density approximation is used. The increased
number of internal (Kohn-Sham) states leads to a generalisation of Hund's first
rule at high densities. At low densitites the formation of Wigner molecules is
favored by the increased internal freedom.Comment: 11 pages, 5 figure
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