22,692 research outputs found
Spontaneous Nambu-Goldstone Currents Generation Driven by Mismatch
We review recent progress of understanding and resolving instabilities driven
by mismatch between the Fermi surfaces of the pairing quarks in 2-flavor color
superconductor. With the increase of mismatch, the 2SC phase exhibits
chromomagnetic instability as well as color neutral baryon current instability.
We describe the 2SC phase in the nonlinear realization framework, and show that
each instability indicates the spontaneous generation of the corresponding
pseudo Nambu-Golstone current. The Nambu-Goldstone currents generation state
covers the gluon phase as well as the one-plane wave LOFF state. We further
point out that, when charge neutrality condition is required, there exists a
narrow unstable LOFF (Us-LOFF) window, where not only off-diagonal gluons but
the diagonal 8-th gluon cannot avoid the magnetic instability. In this Us-LOFF
window, the diagonal magnetic instability cannot be cured by off-diagonal gluon
condensate in the color superconducting phase.Comment: 22 pages, no figures; contribution to the proceedings of the INT
workshop "Pairing in fermionic systems", Seattle, September 19-23, 200
Understanding magnetic instability in gapless superconductors
Magnetic instability in gapless superconductors still remains as a puzzle. In
this article, we point out that the instability might be caused by using BCS
theory in mean-field approximation, where the phase fluctuation has been
neglected. The mean-field BCS theory describes very well the strongly coherent
or rigid superconducting state. With the increase of mismatch between the Fermi
surfaces of pairing fermions, the phase fluctuation plays more and more
important role, and "soften" the superconductor. The strong phase fluctuation
will eventually quantum disorder the superconducting state, and turn the system
into a phase-decoherent pseudogap state.Comment: Proceeding for the "International Conference on QCD and Hadronic
Physics", Jun. 16-20, Beijing, Chin
Holographic description of total hadronic cross sections at high energies
We investigate the hadron-hadron total cross sections at high energies in the
framework of holographic QCD. In our model setup, the involved strong
interaction is described by the Brower-Polchinski-Strassler-Tan Pomeron
exchange kernel, and the two form factors are obtained from the bottom-up
AdS/QCD models. We show that the resulting nucleon-nucleon total cross section
is consistent with the experimental data recently measured by the TOTEM
collaboration at the LHC. As examples to see the general versatility of the
model, we also present our analysis on the pion-nucleon and pion-pion cases,
which can be predicted because all the adjustable parameters are fixed by the
nucleon-nucleon data.Comment: 7 pages, 2 figures, prepared for the proceedings of QCD@Work 2018 -
International Workshop on Quantum Chromodynamics, 25 - 28 June 2018, Matera,
Ital
Dynamical holographic QCD model
We develop a dynamical holographic QCD model, which resembles the
renormalization group from ultraviolet (UV) to infrared (IR). The dynamical
holographic model is constructed in the graviton-dilaton-scalar framework with
the dilaton background field and scalar field responsible for the
gluodynamics and chiral dynamics, respectively. We summarize our results on
hadron spectra, QCD phase transition and transport properties including the jet
quenching parameter and the shear/bulk viscosity in the framework of the
dynamical holographic QCD model.Comment: 8 pages, 5 figures, proceedings for QCD@Work2014, June 16-19,2014,
Bari, Ital
Chromomagnetic instability in dense quark matter
The results for the Debye and Meissner screening masses of the gluons and the
photon in the case of neutral and beta-equilibrated dense two-flavor quark
matter are presented. In the limits of the normal phase and the ideal
two-flavor color superconducting phase, the screening masses coincide with the
known results. Most interestingly, we find that the Meissner screening masses
squared can be negative, indicating a plasma-type chromomagnetic instability in
dense quark matter.Comment: 5 pages and 2 figures. To appear in Phys. Rev. D; version slightly
shortened on request of editor
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