Fine Splitting in Charmonium Spectrum with Channel Coupling Effect

We study the fine splitting in charmonium spectrum in quark model with the channel coupling effect, including $DD$, $DD^*$, $D^*D^*$ and $D_sD_s$, $D_sD_s^*$, $D_s^*D_s^*$ channels. The interaction for channel coupling is constructed from the current-current Lagrangian related to the color confinement and the one-gluon exchange potentials. By adopting the massive gluon propagator from the lattice calculation in the nonperturbative region, the coupling interaction is further simplified to the four-fermion interaction. The numerical calculation still prefers the assignment $1^{++}$ of X(3872).Comment: Submitted to Chinese Physics

Single-photon-assisted entanglement concentration of a multi-photon system in a partially entangled W state with weak cross-Kerr nonlinearity

We propose a nonlocal entanglement concentration protocol (ECP) for $N$-photon systems in a partially entangled W state, resorting to some ancillary single photons and the parity-check measurement based on cross-Kerr nonlinearity. One party in quantum communication first performs a parity-check measurement on her photon in an $N$-photon system and an ancillary photon, and then she picks up the even-parity instance for obtaining the standard W state. When she obtains an odd-parity instance, the system is in a less-entanglement state and it is the resource in the next round of entanglement concentration. By iterating the entanglement concentration process several times, the present ECP has the total success probability approaching to the limit in theory. The present ECP has the advantage of a high success probability. Moreover, the present ECP requires only the $N$-photon system itself and some ancillary single photons, not two copies of the systems, which decreases the difficulty of its implementation largely in experiment. It maybe have good applications in quantum communication in future.Comment: 7 pages, 3 figure

Fortifying Password Authentication in Integrated Healthcare Delivery Systems

Singapore Management Universit

Privacy-Preserving Credentials Upon Trusted Computing Augmented Servers

Abstract. Credentials are an indispensable means for service access control in electronic commerce. However, regular credentials such as X.509 certificates and SPKI/SDSI certificates do not address user pri-vacy at all, while anonymous credentials that protect user privacy are complex and have compatibility problems with existing PKIs. In this pa-per we propose privacy-preserving credentials, a concept between regular credentials and anonymous credentials. The privacy-preserving creden-tials enjoy the advantageous features of both regular credentials and anonymous credentials, and strike a balance between user anonymity and system complexity. We achieve this by employing computer servers equipped with TPMs (Trusted Platform Modules). We present a detailed construction for ElGamal encryption credentials. We also present XML-based specification for the privacy-preserving credentials.

CCA-secure unidirectional proxy re-encryption in the adaptive corruption model without random oracles

Proxy re-encryption (PRE), introduced by Blaze, Bleumer and Strauss in Eurocrypt\u2798, allows a semi-trusted proxy to convert a ciphertext originally intended for Alice into an encryption of the same message intended for Bob. PRE has recently drawn great interest, and many interesting PRE schemes have been proposed. However, up to now, it is still an important question to come up with a chosen-ciphertext secure unidirectional PRE in the adaptive corruption model. To address this problem, we propose a new unidirectional PRE scheme, and prove its chosen-ciphertext security in the adaptive corruption model without random oracles. Compared with the best known unidirectional PRE scheme proposed by Libert and Vergnaud in PKC\u2708, our schemes enjoys the advantages of both higher efficiency and stronger security