10,089 research outputs found
New predictions on the mass of the light hybrid meson from QCD sum rules
We calculate the coefficients of the dimension-8 quark and gluon condensates
in the current-current correlator of light hybrid current
. With inclusion of these
higher-power corrections and updating the input parameters, we re-analyze the
mass of the light hybrid meson from Monte-Carlo based QCD sum rules.
Considering the possible violation of factorization of higher dimensional
condensates and variation of , we obtain a conservative
mass range 1.72--2.60\,GeV, which favors as a better hybrid
candidate compared with and .Comment: 12pages, 2 figures, the version appearing in JHE
CHAOTIC CHARACTER OF SPRINTER'S MYOELECTRIC SIGNAL
There are different myoelectric reactions during muscle's motion when athletes are at different training stage. This study analyzed the myoelectric signal at different training stage of athletes according to chaotic theory and found that there were differences in the spectrum character of myoelectric signal and embedding dimension at different training stage of athletes. The results show that the myoelectric signal spectrum at relaxed status of the muscles mainly presents random noisy spectrum character, but the myoelectric signal spectrum at concentric contraction of the muscles presents divided modality spectrum character. The embedding dimension of myoelectric signal is obviously less at contracted status than at relaxed status. The relative value of embedding dimension of myoelectric signal is far larger during the preparation before tournament than during the transition stage
Unambiguous discrimination of mixed quantum states
In this paper, we consider the problem of unambiguous discrimination between
a set of mixed quantum states. We first divide the density matrix of each mixed
state into two parts by the fact that it comes from ensemble of pure quantum
states. The first part will not contribute anything to the discrimination, the
second part has support space linearly independent to each other. Then the
problem we consider can be reduced to a problem in which the strategy of set
discrimination can be used in designing measurements to discriminate mixed
states unambiguously. We find a necessary and sufficient condition of
unambiguous mixed state discrimination, and also point out that searching the
optimal success probability of unambiguous discrimination is mathematically the
well-known semi-definite programming problem. A upper bound of the optimal
success probability is also presented. Finally, We generalize the concept of
set discrimination to mixed state and point out that the problem of
discriminating it unambiguously is equivalent to that of unambiguously
discriminating mixed states.Comment: 7 page
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