3,482 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
Fragmentation and quark distribution functions for the pion and kaon with explicit flavor-SU(3)-symmetry breaking
We investigate the unpolarized pion and kaon fragmentation functions,
employing the nonlocal chiral-quark model, which manifests the nonlocal
interactions between the quarks and pseudoscalar mesons, considering the
explicit flavor-SU(3)-symmetry breaking in terms of the current-quark masses.
Moreover, we study the quark-distribution functions, derived from the
fragmentation ones with the Drell-Yan-Levi relation. Numerical results are
evaluated to higher Q^2 by the DGLAP evolution and compared with the empirical
data. The ratios between the relevant valance quark-distribution functions are
also discussed. It turns out that the present results are in relatively good
agreement with available data and other theoretical estimations.Comment: 13 pages, 16 figure
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