3,344,664 research outputs found
Lifetimes of Heavy-Flavour Hadrons -- Whence and Whither?
A theoretical treatment for the weak decays of heavy-flavour hadrons has been
developed that is genuinely based on QCD. Its methodology as it applies to
total lifetimes and the underlying theoretical issues are sketched. Predictions
are compared with present data. One discrepancy emerges: the beauty baryon
lifetime appears to be significantly shorter than expected. The ramifications
of those findings are analyzed in detail.Comment: 15 pages, no figures, LATEX, two references added and new information
concerning a lower charm content in B decays incorporate
The Schr\" odinger picture of the Dirac quantum mechanics on spatially flat Robertson-Walker backgrounds
The Schr\" odinger picture of the Dirac quantum mechanics is defined in
charts with spatially flat Robertson-Walker metrics and Cartesian coordinates.
The main observables of this picture are identified, including the interacting
part of the Hamiltonian operator produced by the minimal coupling with the
gravitational field. It is shown that in this approach new Dirac quantum modes
on de Sitter spacetimes may be found analytically solving the Dirac equation.Comment: 6 pages 0 figure
Hidden 12-dimensional structures in AdS(5)xS(5) and M(4)xR(6) Supergravities
It is shown that AdS(5)xS(5) supergravity has hitherto unnoticed
supersymmetric properties that are related to a hidden 12-dimensional
structure. The totality of the AdS(5)xS(5) supergravity Kaluza-Klein towers is
given by a single superfield that describes the quantum states of a
12-dimensional supersymmetric particle. The particle has super phase space
(X,P,Theta) with (10,2) signature and 32 fermions. The worldline action is
constructed as a generalization of the supersymmetric particle action in
Two-Time Physics. SU(2,2|4) is a linearly realized global supersymmetry of the
2T action. The action is invariant under the gauge symmetries Sp(2,R),
SO(4,2),SO(6), and fermionic kappa. These gauge symmetries insure unitarity and
causality while allowing the reduction of the 12-dimensional super phase space
to the correct super phase space for AdS(5)xS(5) or M(4)xR(6) with 16 fermions
and one time, or other dually related one time spaces. One of the predictions
of this formulation is that all of the SU(2,2|4) representations that describe
Kaluza-Klein towers in AdS(5)xS(5) or M(4)xR(6) supergravity universally have
vanishing eigenvalues for all the Casimir operators. This prediction has been
verified directly in AdS(5)xS(5) supergravity. This suggests that the
supergravity spectrum supports a hidden (10,2) structure. A possible duality
between AdS(5)xS(5) and M(4)xR(6) supergravities is also indicated.
Generalizations of the approach applicable 10-dimensional super Yang Mills
theory and 11-dimensional M-theory are briefly discussed.Comment: LaTeX, 32 pages. v2 includes additional generalizations in the
discussion section. The norm of J has been modified in eqs.(2.6, 3.3, 3.8).
v3 includes a correction to Eq.(5.3
Geometric models of (d+1)-dimensional relativistic rotating oscillators
Geometric models of quantum relativistic rotating oscillators in arbitrary
dimensions are defined on backgrounds with deformed anti-de Sitter metrics. It
is shown that these models are analytically solvable, deriving the formulas of
the energy levels and corresponding normalized energy eigenfunctions. An
important property is that all these models have the same nonrelativistic
limit, namely the usual harmonic oscillator.Comment: 7 pages, Late
Comparison Study in Using Plough, Tractor and Cultivator for Rice Field\u27 Land Preparation
Land preparation of the rice field is one of the most important steps for paddyplantation. Formerly plough is one of the main tools for land preparation, but now thefarmer used tractor or cultivator. From the farmer experience who are used that tools forland preparation there had advantages and disadvantages. The used of plough for landpreparation for long time ago the deep of rice field soil is constant because the ploughblade can be adjusted up and down. The plough can be turn to the right or left side so thatall part of rice field except the corner can be cultivate. But for pulling the plough must bedifficult to find two cows. While if using tractor or cultivator the right or left side and thecorner of the rice field can\u27t be cultivate. Deep of rice filed soil become shallow so thefertility of soil reduced. Beside that using tractor or cultivator for land preparation needmore fuel. The plough were easy to carry out, but tractor and cultivator difficult to carryout because the weight more that 200 kg
The leader operators of the -dimensional relativistic rotating oscillators
The main pairs of leader operators of the quantum models of relativistic
rotating oscillators in arbitrary dimensions are derived. To this end one
exploits the fact that these models generate P\"{o}schl-Teller radial problems
with remarkable properties of supersymmetry and shape invariance.Comment: 11 page
Quark deconfinement and neutrino trapping in compact stars
We study the role played by neutrino trapping on the hadron star (HS) to
quark star (QS) conversion mechanism proposed recently by Berezhiani and
collaborators. We find that the nucleation of quark matter drops inside hadron
matter, and therefore the conversion of a HS into a QS, is strongly inhibit by
the presence of neutrinos.Comment: 3 pages, 3 figures. Talk given at the VIII International Conference
on Strangeness in Quark Matter. Cape Town, South Africa, Septembre 200
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