35,307 research outputs found
Experimental tests on the lifetime Asymmetry
The experimental test problem of the left-right polarization-dependent
lifetime asymmetry is discussed. It shows that the existing experiments cannot
demonstrate the lifetime asymmetry to be right or wrong after analyzing the
measurements on the neutron, the muon and the tau lifetime, as well as the
experiment. However, It is pointed out emphatically that the SLD and the
E158 experiments, the measurements of the left-right integrated cross section
asymmetry in boson production by collisions and by
electron-electron M{\o}ller scattering, can indirectly demonstrate the lifetime
asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose
some possible experiments on the decays of polarized muons. The precise
measurement of the lifetime asymmetry could have important significance for
building a muon collider, also in cosmology and astrophysics. It would provide
a sensitive test of the standard model in particle physics and allow for
exploration of the possible interactions.Comment: 11 pages, 1 figur
Quantum state transfer via the ferromagnetic chain in a spatially modulated field
We show that a perfect quantum state transmission can be realized through a
spin chain possessing a commensurate structure of energy spectrum, which is
matched with the corresponding parity. As an exposition of the mirror inversion
symmetry discovered by Albanese et. al (quant-ph/0405029), the parity matched
the commensurability of energy spectra help us to present the novel
pre-engineered spin systems for quantum information transmission. Based on the
these theoretical analysis, we propose a protocol of near-perfect quantum state
transfer by using a ferromagnetic Heisenberg chain with uniform coupling
constant, but an external parabolic magnetic field. The numerical results shows
that the initial Gaussian wave packet in this system with optimal field
distribution can be reshaped near-perfectly over a longer distance.Comment: 5 pages, 2 figure
PDMS/PVA composite ferroelectret for improved energy harvesting performance
This paper address the PDMS ferroelectret discharge issue for improved long- term energy harvesting performance. The PDMS/PVA ferroelectret is fabricated using a 3D-printed plastic mould technology and a functional PVA composite layer is introduced. The PDMS/PVA composite ferroelectret achieved 80% piezoelectric coefficient d33 remaining, compared with 40% without the proposed layer over 72 hours. Further, the retained percentage of output voltage is about 73% over 72 hours
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On defining partition entropy by inequalities
Partition entropy is the numerical metric of uncertainty within
a partition of a finite set, while conditional entropy measures the degree of
difficulty in predicting a decision partition when a condition partition is
provided. Since two direct methods exist for defining conditional entropy
based on its partition entropy, the inequality postulates of monotonicity,
which conditional entropy satisfies, are actually additional constraints on
its entropy. Thus, in this paper partition entropy is defined as a function
of probability distribution, satisfying all the inequalities of not only partition
entropy itself but also its conditional counterpart. These inequality
postulates formalize the intuitive understandings of uncertainty contained
in partitions of finite sets.We study the relationships between these inequalities,
and reduce the redundancies among them. According to two different
definitions of conditional entropy from its partition entropy, the convenient
and unified checking conditions for any partition entropy are presented, respectively.
These properties generalize and illuminate the common nature
of all partition entropies
Modelling thermomechanical behaviour of Cr-Mo-V steel
This paper presents a mechanism-based approach for modelling the thermomechanical behaviour of a Cr-Mo-V steel. A set of unified viscoplastic constitutive equations were employed to model dislocation density, recrystallisation and grain size during deformation. The evolution of dislocation density accounts for the build-up of dislocations due to plastic strain, the static and dynamic recovery and the effect of recrystallisation. Recrystallisation occurs when a critical dislocation density is reached after an incubation time, and grain size becomes smaller after such event. Gleeble compression tests were used to obtain Stress-strain curves and evaluate the microstructural evolution at different temperature and strain rate, and the material constants for the model were determined from the experimental data. Copyright © 2010 MS&T10®
Heavy Pentaquarks
We construct the spin-flavor wave functions of the possible heavy pentaquarks
containing an anti-charm or anti-bottom quark using various clustered quark
models. Then we estimate the masses and magnetic moments of the or heavy pentaquarks. We emphasize the difference in the
predictions of these models. Future experimental searches at BESIII, CLEOc,
BELLE, and LEP may find these interesting states
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