11,586 research outputs found
Commutator Leavitt path algebras
For any field K and directed graph E, we completely describe the elements of
the Leavitt path algebra L_K(E) which lie in the commutator subspace
[L_K(E),L_K(E)]. We then use this result to classify all Leavitt path algebras
L_K(E) that satisfy L_K(E)=[L_K(E),L_K(E)]. We also show that these Leavitt
path algebras have the additional (unusual) property that all their Lie ideals
are (ring-theoretic) ideals, and construct examples of such rings with various
ideal structures.Comment: 24 page
How Stands Collapse II
I review ten problems associated with the dynamical wave function collapse
program, which were described in the first of these two papers. Five of these,
the \textit{interaction, preferred basis, trigger, symmetry} and
\textit{superluminal} problems, were discussed as resolved there. In this
volume in honor of Abner Shimony, I discuss the five remaining problems,
\textit{tails, conservation law, experimental, relativity, legitimization}.
Particular emphasis is given to the tails problem, first raised by Abner. The
discussion of legitimization contains a new argument, that the energy density
of the fluctuating field which causes collapse should exert a gravitational
force. This force can be repulsive, since this energy density can be negative.
Speculative illustrations of cosmological implications are offered.Comment: 37 page
Flavour Symmetries and Kahler Operators
Any supersymmetric mechanism to solve the flavour puzzle would generate
mixing both in the superpotential Yukawa couplings and in the Kahler potential.
In this paper we study, in a model independent way, the impact of the
nontrivial structure of the Kahler potential on the physical mixing matrix,
after kinetic terms are canonically normalized. We undertake this analysis both
for the quark sector and the neutrino sector. For the quark sector, and in view
of the experimental values for the masses and mixing angles, we find that the
effects of canonical normalization are subdominant. On the other hand, for the
leptonic sector we obtain different conclusions depending on the spectrum of
neutrinos. In the hierarchical case we obtain similar conclusion as in the
quark sector, whereas in the degenerate and inversely hierarchical case,
important changes in the mixing angles could be expected.Comment: 22 pages, LaTe
Pelatihan Pliometrik Jump to Box Lebih Meningkatkan Daya Ledak Otot Tungkai Dari Pada Pelatihan Pliometrik Barrier Hops Pada Permainan Bola Basket
Penelitian ini bertujuan untuk membandingkan pelatihan jump to box dan barrier hops terhadap peningkatan daya ledak otot tungkai. Penelitian ini dilakukan terhadap 32 orang siswa SMK Negeri 1 Kuta Selatan yang dipilih secara acak sederhana yang telah memenuhi kriteria insklusi dan eksklusi. Sampel dibagi menjadi dua kelompok sehingga masing-masing kelempok berjumlah 16 orang dan diberikan perlakuan yang berbeda selama enam minggu. Kelompok satu diberikan pelatihan jump to box dan kelompok dua diberikan pelatihan barrier hops. Data yang didapat dianalisis dengan uji t paired untuk mengethui perbedaan antara sebelum dan sesudah pelatihan pada kedua kelompok dan uji t-independent untuk menguji perbedaan daya ledak otot tungkai antar kelompok baik sebelum maupun sesudah pelatihan. Batas kemaknaan di pakai 0,05. Hasil penelitian menunjukan rerata daya ledak otot tungkai antar kelompok sesudah pelatihan sebesar 58,00±10,33 cm pada kelompok jump to box dan pada kelompok barrier hops sebesar 50,49±10,19 cm. Rerata daya ledak otot tungkai pelatihan jump to box lebih tinggi dibandingkan dengan pelatihan barrier hops yang secara statistik berbeda bermakna dengan nilai p=0,036 (p<0,05). Dengan demikian, pelatihan jump to box dan pelatihan barrier hops dapat meningkatkan daya ledak otot tungkai, di mana pelatihan jump to box lebih meningkatkan daripada pelatihan barrier hops
Green Function on the q-Symmetric Space SU_q(2)/U(1)
Following the introduction of the invariant distance on the non-commutative
C-algebra of the quantum group SU_q(2), the Green function and the Kernel on
the q-homogeneous space M=SU(2)_q/U(1) are derived. A path integration is
formulated. Green function for the free massive scalar field on the
non-commutative Einstein space R^1xM is presented.Comment: Plain Latex, 19
Prospects for SIMPLE 2000: A large-mass, low-background Superheated Droplet Detector for WIMP searches
SIMPLE 2000 (Superheated Instrument for Massive ParticLE searches) will
consist of an array of eight to sixteen large active mass ( g)
Superheated Droplet Detectors(SDDs) to be installed in the new underground
laboratory of Rustrel-Pays d'Apt. Several factors make of SDDs an attractive
approach for the detection of Weakly Interacting Massive Particles (WIMPs),
namely their intrinsic insensitivity to minimum ionizing particles, high
fluorine content, low cost and operation near ambient pressure and temperature.
We comment here on the fabrication, calibration and already-competitive first
limits from SIMPLE prototype SDDs, as well as on the expected immediate
increase in sensitivity of the program, which aims at an exposure of 25
kg-day during the year 2000. The ability of modest-mass fluorine-rich detectors
to explore regions of neutralino parameter space beyond the reach of the most
ambitious cryogenic projects is pointed out.Comment: 19 pages, 10 figures included. New Journal of Physics, in pres
Excited Random Walk in One Dimension
We study the excited random walk, in which a walk that is at a site that
contains cookies eats one cookie and then hops to the right with probability p
and to the left with probability q=1-p. If the walk hops onto an empty site,
there is no bias. For the 1-excited walk on the half-line (one cookie initially
at each site), the probability of first returning to the starting point at time
t scales as t^{-(2-p)}. Although the average return time to the origin is
infinite for all p, the walk eats, on average, only a finite number of cookies
until this first return when p<1/2. For the infinite line, the probability
distribution for the 1-excited walk has an unusual anomaly at the origin. The
positions of the leftmost and rightmost uneaten cookies can be accurately
estimated by probabilistic arguments and their corresponding distributions have
power-law singularities near the origin. The 2-excited walk on the infinite
line exhibits peculiar features in the regime p>3/4, where the walk is
transient, including a mean displacement that grows as t^{nu}, with nu>1/2
dependent on p, and a breakdown of scaling for the probability distribution of
the walk.Comment: 14 pages, 13 figures, 2-column revtex4 format, for submission to J.
Phys.
Critical behaviour of a surface reaction model with infinitely many absorbing states
In a recent letter [J. Phys. A26, L801 (1993)], Yaldram et al. studied the
critical behaviour of a simple lattice gas model of the CO-NO catalytic
reaction. The model exhibits a second order nonequilibrium phase transition
from an active state into one out of infinitely many absorbing states.
Estimates for the critical exponent suggested that the model belongs to
a new universality class. The results reported in this article contradict this
notion, as estimates for various critical exponents show that the model belongs
to the universality class of directed percolation.Comment: 10p+5fig, LaTeX+fig in uuencoded P
Visibility diagrams and experimental stripe structure in the quantum Hall effect
We analyze various properties of the visibility diagrams that can be used in
the context of modular symmetries and confront them to some recent experimental
developments in the Quantum Hall Effect. We show that a suitable physical
interpretation of the visibility diagrams which permits one to describe
successfully the observed architecture of the Quantum Hall states gives rise
naturally to a stripe structure reproducing some of the experimental features
that have been observed in the study of the quantum fluctuations of the Hall
conductance. Furthermore, we exhibit new properties of the visibility diagrams
stemming from the structure of subgroups of the full modular group.Comment: 8 pages in plain TeX, 7 figures in a single postscript fil
Cornering Solar Radiative-Zone Fluctuations with KamLAND and SNO Salt
We update the best constraints on fluctuations in the solar medium deep
within the solar Radiative Zone to include the new SNO-salt solar neutrino
measurements. We find that these new measurements are now sufficiently precise
that neutrino oscillation parameters can be inferred independently of any
assumptions about fluctuation properties. Constraints on fluctuations are also
improved, with amplitudes of 5% now excluded at the 99% confidence level for
correlation lengths in the range of several hundred km. Because they are
sensitive to correlation lengths which are so short, these solar neutrino
results are complementary to constraints coming from helioseismology.Comment: 4 pages, LaTeX file using RevTEX4, 6 figures include
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