2,919 research outputs found
CP Violation and Arrows of Time Evolution of a Neutral or Meson from an Incoherent to a Coherent State
We study the evolution of a neutral meson prepared as an incoherent equal
mixture of and . Denoting the density matrix by \rho(t) =
{1/2} N(t) [\1 + \vec{\zeta}(t) \cdot \vec{\sigma} ] , the norm of the state
is found to decrease monotonically from one to zero, while the magnitude
of the Stokes vector increases monotonically from zero to
one. This property qualifies these observables as arrows of time. Requiring
monotonic behaviour of for arbitrary values of and
yields a bound on the CP-violating overlap , which is similar to, but weaker than, the known unitarity
bound. A similar requirement on yields a new bound,
which is particularly effective in limiting
the CP-violating overlap in the - system. We obtain the Stokes
parameter which shows how the average strangeness of the beam
evolves from zero to . The evolution of the Stokes vector from
to has a resemblance to an order
parameter of a system undergoing spontaneous symmetry breaking.Comment: 13 pages, 6 figures. Inserted conon "." in title; minor change in
text. To appear in Physical review
Unstable particles as open quantum systems
We present the probability preserving description of the decaying particle
within the framework of quantum mechanics of open systems taking into account
the superselection rule prohibiting the superposition of the particle and
vacuum. In our approach the evolution of the system is given by a family of
completely positive trace preserving maps forming one-parameter dynamical
semigroup. We give the Kraus representation for the general evolution of such
systems which allows one to write the evolution for systems with two or more
particles. Moreover, we show that the decay of the particle can be regarded as
a Markov process by finding explicitly the master equation in the Lindblad
form. We also show that there are remarkable restrictions on the possible
strength of decoherence.Comment: 11 pp, 2 figs (published version
Paramaterizations of inclusive cross sections for pion production in proton-proton collisions. II. Comparison to new data
A set of new, precise data have recently been made available by the NA49
collaboration for charged pion production in proton-proton and proton-Carbon
reactions at 158 GeV. The current paper compares this new data to five
currently available arithmetic parameterizations. Although a precise fit is not
expected, two of the parameterizations do not work very well but the other
three are able to provide a moderately good, but not precise fit to the
proton-proton data. The best two of these three parameterizations are scaled to
the proton-Carbon data and again provide a moderately good, but not precise
fit.Comment: 11 pages, 13 figures, Accepted for publication in Physical Review
Dynamic light- and acetate-dependent regulation of the proteome and lysine acetylome of Chlamydomonas
Time Asymmetric Quantum Physics
Mathematical and phenomenological arguments in favor of asymmetric time
evolution of micro-physical states are presented.Comment: Tex file with 2 figure
QCD corrections to the decay in the Minimal Supersymmetric Standard Model
We present a complete calculation of the QCD corrections (of the order
) to the width of the decay within the Minimal
Supersymmetric Standard Model. We find that the QCD corrections are quite
important, and that the supersymmetric QCD corrections (due to gluino, stop and
sbottom exchange) can be comparable to or even larger than the standard QCD
corrections in a large region of the supersymmetric parameter space. This is
mainly due to the effect of large left-right mixings of stop and sbottom. This
could significantly affect the phenomenology of the search.Comment: 12 pages latex, 5 uuencoded figures, LateX file of text and PS-files
of the text and the figures are also available via anonymous ftp at
ftp://info.oeaw.ac.at/pub/hephy-pub/631 . Figures have been changed (and fig.
5 added), and accordingly the discussion of thes
Measurement of the branching ratio of the decay
From the 2002 data taking with a neutral kaon beam extracted from the
CERN-SPS, the NA48/1 experiment observed 97 candidates with a background contamination of events.
From this sample, the BR() is measured to be
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