401,812 research outputs found

    Multipartite entanglement of fermionic systems in noninertial frames

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    The bipartite and tripartite entanglement of a 3-qubit fermionic system when one or two subsystems accelerated are investigated. It is shown that all the one-tangles decrease as the acceleration increases. However, unlike the scalar case, here one-tangles NCI(ABI){\cal N}_{C_I(AB_I)} and NCI(AB){\cal N}_{C_I(AB)} never reduce to zero for any acceleration. It is found that the system has only tripartite entanglement when either one or two subsystems accelerated, which means that the acceleration doesn't generate bipartite entanglement and doesn't effect the entanglement structure of the quantum states in this system. It is of interest to note that the π\pi-tangle of the two-observers-accelerated case decreases much quicker than that of the one-observer-accelerated case and it reduces to a non-zero minimum in the infinite acceleration limit. Thus we argue that the qutrit systems are better than qubit systems to perform quantum information processing tasks in noninertial systems.Comment: 12 pages, 3 figure

    RbR_b in supergravity models

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    We compute the supersymmetric contribution to Rb≡Γ(Z→bbˉ)/Γ(Z→hadrons)R_{b}\equiv \Gamma (Z\to b{\bar b})/\Gamma (Z\to {\rm hadrons}) in a variety of supergravity models. We find R^{\rm susy}_b\lsim0.0004, which does not shift significantly the Standard Model prediction (RbSM=0.2162R^{\rm SM}_b=0.2162 for m_t=160\GeV). An improvement in experimental precision by a factor of four would be required to be sensitive to such an effect.Comment: 5 pages, LaTeX, 1 figure (included)

    Ellsberg Paradox: Ambiguity And Complexity Aversions Compared

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    We present a simple model where preferences with complexity aversion, rather than ambiguity aversion, resolve the Ellsberg paradox. We test our theory using laboratory experiments where subjects choose among lotteries that “range” from a simple risky lottery, through risky but more complex lotteries, to one similar to Ellsberg’s ambiguity urn. Our model ranks lotteries according to their complexity and makes different—at times contrasting—predictions than most models of ambiguity in response to manipulations of prizes. The results support that complexity aversion preferences play an important and separate role from beliefs with ambiguity aversion in explaining behavior under uncertainty

    RiffleScrambler - a memory-hard password storing function

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    We introduce RiffleScrambler: a new family of directed acyclic graphs and a corresponding data-independent memory hard function with password independent memory access. We prove its memory hardness in the random oracle model. RiffleScrambler is similar to Catena -- updates of hashes are determined by a graph (bit-reversal or double-butterfly graph in Catena). The advantage of the RiffleScrambler over Catena is that the underlying graphs are not predefined but are generated per salt, as in Balloon Hashing. Such an approach leads to higher immunity against practical parallel attacks. RiffleScrambler offers better efficiency than Balloon Hashing since the in-degree of the underlying graph is equal to 3 (and is much smaller than in Ballon Hashing). At the same time, because the underlying graph is an instance of a Superconcentrator, our construction achieves the same time-memory trade-offs.Comment: Accepted to ESORICS 201

    The significance of information visualisation based on the symbolic semantics of Peking Opera Painted Faces (POPF)

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    Peking Opera as a branch of Chinese traditional cultures and arts has a very distinct colourful facial make-up for all actors in the stage performance. Such make-up is stylised in typical cultural elements which all combined together to form the painted faces to describe and symbolise the background and characteristic of specific roles. The Peking Opera Painted Faces (POPF) was taken as an example to study the information visualisation and transmission, to see how information and meanings can be effectively expressed through the colourful visual elements. In order to identify the state-of-the-art in the related Culture Inspired Design as one of the design principles, the literature resources including illustrations of POPF were investigated, and also the semantic features and elements of other similar forms of modern design which has close connection with multiple aspects of social life. The study has proved that the visual elements of POPF played the most effective role in the information transmittion. Future application of this culture resource may include product design, interaction design, system design and service design around the world

    Primitive Cohomology of Hopf algebras

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    Primitive cohomology of a Hopf algebra is defined by using a modification of the cobar construction of the underlying coalgebra. Among many of its applications, two classifications are presented. Firstly we classify all non locally PI, pointed Hopf algebra domains of Gelfand-Kirillov dimension two; and secondly we classify all pointed Hopf algebras of rank one. The first classification extends some results of Brown, Goodearl and others in an ongoing project to understand all Hopf algebras of low Gelfand-Kirillov dimension. The second generalizes results of Krop-Radford and Wang-You-Chen which classified Hopf algebras of rank one under extra hypothesis. Properties and algebraic structures of the primitive cohomology are discussed
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