Transcript Test string theory with primordial gravitational wave

Low-energy
effective string theory
in primordial gravitational wave
朴云松
University of CAS
USTC-ICTS，2015.4.23
一、动机
二、我们的工作
三、讨论
Based on 1501.06345, PRD,
with Yong Cai and Yu-Tong Wang
The paradigm of early universe: inflation
(alternatives ?)
Planck 2015 results
As a laboratory
?
inflation
sub-Planck scale
LHC
1、Primordial scalar perturbation
Planck限制,
原初的 “污染”源多
2、Primordial gravitational wave
目前只有上限,
没有原初的“污染”源
inflationary
gravitational wave
BICEP2/Keck and Planck 2015
inflationary lab
string theory
primordial gravitational wave
can be non-trivial?
一个例子：
the low-energy effective action
of heterotic string is
Metsaev,Tseytlin, Nucl.Phys.B293, 385 (1987)
二、我们的工作
The primordial GW
Beyond GR
the effective Planck scale
the propagating speed
The effect is negligible,
if
and
The change of speed
Gasperini,Veneziano 2002
The change of speed
may be non-trivial.
The effect of
non-trivial change of speed
The equation is
Inflation background
Initially,
the mode is in Bunch-Davis state
this sets
Inflation background
and
are determined by the matching conditions.
The perturbation is
,
The result of primordial GWs
The character scale
is that of slow-roll inflation
Detail of the GWs
is inflationary-like
However, the oscillation
appear for
The oscillation can
be attributed to other mechanism?
1、
is oscillating, hardly implemented.
2、The production of particles,
only a bump-like behavior.
Gary Shiu et.al 1405.0346
Transfer to
B-mode polarization spectrum
l=2,65
is the optical depth
三、Discussion
The assumptions:
1、Inflation is the paradigm of early universe.
2、The higher-order derivative terms in superstring
theory is significant.
alter
The conclusion:
The oscillating GWs
is imprinted in
CMB B-mode polarization.
Hope r>0.01.
The physics of oscillation
The low-energy effective action of superstring
alters the initial state of mode
The Bunch-Davis state
only for mode
but for mode
Note: initial state is not
altered by
The outlook:
r =0.05+lense
By Yu-Tong Wang
WMAP 3-year 2006
Tegmark, ApJ 464, L35 1996
The history of
CMB TT spectrum
observations
Planck 2015
Thank You !