22,291 research outputs found

    The Happer's puzzle degeneracies and Yangian

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    We find operators distinguishing the degenerate states for the Hamiltonian H=x(K+1/2)Sz+KSH= x(K+{1/2})S_z +{\bf K}\cdot {\bf S} at x=±1x=\pm 1 that was given by Happer et al[1,2]^{[1,2]} to interpret the curious degeneracies of the Zeeman effect for condensed vapor of 87^{87}Rb. The operators obey Yangian commutation relations. We show that the curious degeneracies seem to verify the Yangian algebraic structure for quantum tensor space and are consistent with the representation theory of Y(sl(2))Y(sl(2)).Comment: 8 pages, Latex fil

    Thermoelectric DC conductivities with momentum dissipation from higher derivative gravity

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    We present a mechanism of momentum relaxation in higher derivative gravity by adding linear scalar fields to the Gauss-Bonnet theory. We analytically computed all of the DC thermoelectric conductivities in this theory by adopting the method given by Donos and Gauntlett in [arXiv:1406.4742]. The results show that the DC electric conductivity is not a monotonic function of the effective impurity parameter β\beta: in the small β\beta limit, the DC conductivity is dominated by the coherent phase, while for larger β\beta, pair creation contribution to the conductivity becomes dominant, signaling an incoherent phase. In addition, the DC heat conductivity is found independent of the Gauss-Bonnet coupling constant.Comment: 1+19 pages, 2 figures,typos in Eq.(40) correcte

    Deciphering a novel image cipher based on mixed transformed Logistic maps

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    Since John von Neumann suggested utilizing Logistic map as a random number generator in 1947, a great number of encryption schemes based on Logistic map and/or its variants have been proposed. This paper re-evaluates the security of an image cipher based on transformed logistic maps and proves that the image cipher can be deciphered efficiently under two different conditions: 1) two pairs of known plain-images and the corresponding cipher-images with computational complexity of O(218+L)O(2^{18}+L); 2) two pairs of chosen plain-images and the corresponding cipher-images with computational complexity of O(L)O(L), where LL is the number of pixels in the plain-image. In contrast, the required condition in the previous deciphering method is eighty-seven pairs of chosen plain-images and the corresponding cipher-images with computational complexity of O(27+L)O(2^{7}+L). In addition, three other security flaws existing in most Logistic-map-based ciphers are also reported.Comment: 10 pages, 2 figure
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