The CMB anomaliesThe CMB anomalies

with a bouncing inflation with a bouncing inflation

朴云松（朴云松（ Y.S. PiaoY.S. Piao ））

I. The motivation: CMB anomalies

II. Our viewpoint: CMB anomalies is a hint of preinflationary physics

III. Our model

Based on collaboration with Guo and Liu

arXiv:1304.6527

I. The motivation

Inflation is the current paradigm of early universe.

I. The motivation

The Planck’s results No Non-GaussiangityNo running

The Planck’s results

I. The motivation

I. The motivation

The Planck confirmed1. deficit of power on large angular scales

I. The motivation

The Planck confirmed2. power asymmetry on large angular scales

ˆ ˆ ˆ ˆ T n =s n 1+A n p

Dipole modulation

0.07 0.02 A

II. Our viewpoint

Why both the deficit of power and the power asymmetry appeared simultaneously on large angular scales ?

We think this is not accidental.

/lsx l

Dipole modulation

The CMB power asymmetry may be modeled as a dipole modulation of power.

kA

Erickcek et.alLyth,fluctuation mode

Dipole modulation

The modulation can be explained in light of

kA

Lyth, Liu, Guo, Piao

/lsx l

Dipole modulation

is determined by the observation on corresponding scales

The result is < 0.1

Erickcek et.alLyth,Thus for single inflation model

310kA

which is not consistent with Planck data.

II. Our viewpoint

We think: both the large modulation and the deficit of power implies on large angular scales

the anomalies on large angular scales is a hint of the preinflationary physics.

1 1 Rn k

III. Our model

Ten years ago

Ten years ago

III. Our model

III. The bounce model

Before 03, modified gravity Pre-big bang, ekpyrotic universe After 03, GR and field breaking null energy condition Ghostfree models ghost condensation (new ekpyrotic universe), G-bounce

a

t

Any of these mechanisms may apply to our model, the result is not affected, since the bounce does not alter the spectrum of primordial perturbation.

III. Our model

before the bounce, the field will climb up along its potential.

after the bounce, It rolls down.

The scenario: initially the universe is in a contracting phase, then it bounces into a slowroll inflationary phase.

III. Our model

The evolution of background (numerical)

III. Our model

The evolution of background is approximately

is the comoving Hubble scale at matching surface

III. Our model

The equation of is

where is defined,

III. Our model

In the contracting phase

In the inflationary phase

III. Our model

all physical quantities should continuously pass through the bounce.

Liu, Piao, Phys.Rev.D86, 083510 (2012)

III. Our model

Thus the continuity of brings

III. Our model

III. Our model

III. Our model

Planck used cutoff model Our model

III. Our model

III. Our model

The implication to the eternal inflation scenario in landscape

the bouncing inflation is a favored channel to implement the slow roll inflation.

IV. Conclusion

The anomalies appeared simultaneously is not accidental, which is a significant hint of

Pre-inflationary physics.

the string theory ?

Thank You!