Activity Report on Holographic
My Research
QCD in E01
Shin Nakamura
(Dept. of Physics, Kyoto Univ.)
Holographic QCD
(AdS/CFT correspondence)
A useful tool for non-perturbative analysis
of strongly-interacting gauge theories.
Our aim is to apply this technique to uncover a new
physics as a “New Hadron” project.
To achieve this, we need the following two points of view:
• Improvement of the AdS/CFT framework.
• Application to a good problem.
Main work in the academic year of 2010:
the improvement of the framework,
(and finding “good” problems to attack).
• Challenge to non-equilibrium physics
S. N. ,Prog. Theor. Phys. 124 (2010), 1105-1114,
arXiv:1006.4105 [hep-th].
Chiral-symmetry restoration at far from equilibrium.
• (Towards) Improvement of the Sakai-Sugimoto model
Work in progress,
with H. Suganuma (Kyoto) and K. Nawa (RCNP).
Hope to apply to hadron spectrum (scalar mode).
Nontrivial problems of SSB
(Jona-Lasinio, 2010)
SSB in non-equilibrium processes
Superfluid He flow : Bose condensation
of NG phonon modes
1-D phase transition not possible, but
1-D highway traffic model (Popkov et al 2008)
>------------ ↘ _________ ↗ ------------->
<------------ ↗
↘ -------------<
Role of SSB in cosmology?
Prof. Y. Nambu’s slide @ Baryons’10
Application to non-equilibrium physics
A “first-principle” estimation of non-linear transport
of quark charge in an sQGP-like state.
In strongly-correlated electron systems, the nonlinear conductivity
with negative slope (negative differential conductivity, NDC) is
widely observed in various materials.
E
NDC
However, only the phenomenological
approaches are available in the market.
I have reproduced the qualitatively
similar NDC from a microscopic theory
by using the AdS/CFT technique.
J
Consider the transport of quark charge
Same temperature
quark
External Field
bound state
anti-quark
gluon
High ET
Low
LowET
Bound states: neutral in the quark charge
sQGP: insulator
QGP: conductor/ “metal”
“Metal/insulator transition” of the meson gas
The model may also qualitatively imitate the physics
of electron-hole bound states (excitons).
J-E chracteristics from AdS/CFT
mq=1.315 (in N=4 SYM + N=2 hypermultiplet)
There is an upper bound for
the electric field to allow
the NDC.
E
Insulation breaking at the
critical electric field.
～1×10-4 mA/(mm)2
～0.5 V/m
NDC
J
Possible applications in quark-hadron physics:
oscillations in neutron stars?
J=0 branch exists
If we use “meV”
(mili-electron volt)
as the unit.
Temperature: ～5 K
Fine structure constant
read form the Coulomb
interaction：～O(1)
Improvement of
the Sakai-Sugimoto model
The best holographic QCD model so far:
the Sakai-Sugimoto model
However, there are several problems to be settled:
a) realization of the dimensional transmutation
b) clarification of the un-known parameter in the model
Un-known parameter:
the separation (L) between the D8 and the D8-bar
L
This affects the physics but the physical meaning is not entirely clear.
(Cf. Some argument on 4-fermi interactions: E. Antonyan et. al. 1996)
Trying to clarify the meaning and to apply the computation
of the hadron spectrum. (with H. Suganuma and K. Nawa)
Perspectives for
the coming academic year
• Improvement of the Sakai-Sugimoto model:
hope to find some connection to the experiments
in “new-hadron project.”
• Application to non-equilibrium physics:
some more collaborations with condensed-matter
physicists; a new framework from “New Hadron.”
• Some more projects
Other related activities
Lectures on AdS/CFT:
• “New hadron special lectures on holographic QCD”
@ Kyoto Univ., June 2010
• “New hadron summer school”
@ RCNP, Aug. 2010
• + two more invited lectures
Hope to report many scientific results in the
next-year’s meeting.
Direction of “nuclear physics”?
My discovery: nuclear physics = quantum many-body physics
量子多体物理学