6,369 research outputs found
Peak-Dip-Hump from Holographic Superconductivity
We study the fermionic spectral function in a holographic superconductor
model. At zero temperature, the black hole has zero horizon and hence the
entropy of the system is zero after the back reaction of the condensate is
taken into account. We find the system exhibits the famous peak-dip-hump
lineshape with a sharp low-energy peak followed by a dip then a hump at higher
energies. This feature is widely observed in the spectrum of several high-T_c
superconductors. We also find a linear relation between the gap in the
fermionic spectrum and the condensate, indicating the condensate is formed by
fermion pairing.Comment: 4 pages, revtex
The loop corrections to the parity-violating electron-proton elastic scattering
We calculate the two-boson-exchange (TBE) corrections to the parity asymmetry
of the elastic electron-proton scattering in a model using the formalism of
generalized parton distributions (GPDs).Comment: 7 pages, talk given at "Particle Physics, Astrophysics and Quantum
Field Theory, 75 years since Solvay" 27th-29th Nov, 2008, Singapor
The Intention to Download Music Files in a P2P Environment: Rational Choice, Fashion, and Ethical Decision Perspectives
Downloading unauthorized music file is deemed illegal and immoral, but the peer-to-peer systems have boosted its popularity. Many authors attributed this phenomenon to the low morality of Internet users, but inconclusive evidence to this argument was found. Extant literature seldom noticed that downloading music files is a new mean of music consumption. People, especially young generation, might rationally choose between downloading music files and buying CDs for greater utility for enjoying and pursuing after the fashion of music. This paper presents a conceptual model of file downloading by looking at and integrating these perspectives. An analysis of 834 samples drew from a questionnaire survey of P2P users in Taiwan generally supports the above assertion
Supersolidity from defect-condensation in the extended boson Hubbard model
We study the ground state phase diagram of the hard-core extended boson
Hubbard model on the square lattice with both nearest- (nn) and
next-nearest-neighbor (nnn) hopping and repulsion, using Gutzwiller mean field
theory and quantum Monte Carlo simulations. We observe the formation of
supersolid states with checkerboard, striped, and quarter-filled crystal
structures, when the system is doped away from commensurate fillings. In the
striped supersolid phase, a strong anisotropy in the superfluid density is
obtained from the simulations; however, the transverse component remains
finite, indicating a true two-dimensional superflow. We find that upon doping,
the striped supersolid transitions directly into the supersolid with
quarter-filled crystal structure, via a first-order stripe melting transition.Comment: Revtex 4, 6 pages, 9 figure
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