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M-flation after BICEP2
Amjad Ashoorioon (Lancaster University)
Based onA.A, M.M. Sheikh-Jabbari, arXiv:1405.1685 [hep-th]] and A.A., H. Firouzjahi, M.M. Sheikh-Jabbari JCAP 0906:018,2009, arXiv:0903.1481 [hep-th],A.A., H. Firouzjahi, M.M. Sheikh-Jabbari JCAP 1005 (2010) 002, arXiv:0911.4284 [hep-th]A.A.,M.M. Sheikh-Jabbari, JCAP 1106 (2011) 014, arXiv:1101.0048 [hep-th]A.A., U.Danielsson, M. M. Sheikh-Jabbari, Phys.Lett. B713 (2012) 353, arXiv:1112.2272 [hep-th]
Cosmo 2014Chicago, ILAugust 25th, 2014
Mainly in collaboration withShahin Sheikh-Jabbari (IPM)
Introduction
The increasingly precise CMB measurements by Planck mission in combination with other cosmological date have ushered us into a precision early Universe cosmology era:
ππ β‘π logπ π
π logπ+1=0.9603Β±0.0073
π β€0.11 ;
Planck 2013
Introduction BICEP2 surprise: claims that have observed the B-modes with at
o To embed such a model in supergravity, one has to insure the flatness of the theory on scales
Lyth (1997)
o In stringy models, due to geometric origin of inflation in higher dimensions,
McAllister & Baumann (2007)
Detection of poses theoretical model-building challenges:
Ξππππ
β₯1.06( π0.01 )
1/2
From Planck experiment: at
π=0.2β 0.05+0.07
.
A priori these two experiments are not mutually-exclusive and can be reconciled
A.A., K. Dimopoulos, M.M. Sheikh-Jabbari, G. Shiu, JCAP 1402 (2014) 025, arXiv:1306.4914 A.A., K. Dimopoulos, M.M. Sheikh-Jabbari, G. Shiu, arXiv:1403.6099 [hep-th]], to appear in PLB
Realization of Large-Field Models in String Theory
o An individual axionic field, whose potential is shift symmetric. in presence of fluxes spirals super-Planckian distances
Monodromy InflationSilverstein & Westphal (2008)
McAllister, Silverstein, Westphal (2009)
o Many moduli, which could be axions or not, cooperate to cause inflation.
o Even though the effective field excursion is larger than , individual field displacement is less!
N-flation, Kachru et. al (2006)M-flation, Ashoorioon & Sheikh-Jabbari (2009)Multiple M5 brane Inflation, A. Krause, M. Becker, K, Becker (2005) A. Ashoorioon & A. Krause (2006)
See Garyβs and Evaβs Talks
β’ Gauged M-flation
FFCXX
l
igQgxd
glS
IJ
JI
s
sIJab
ss 4
1 ,
4||1STr
)2(
1 )6(2
443 0123
Myers (1999)
Nb
MaMNab XXGg 9 ..., ,1 ,0, NM 9,...,5,4, JI
3 2, 1, ,0, ba JI
s
IJIJ XXl
iQ ,
2 2
8
1
3
1
2222 )()(Λ2K
KKi
i dxdxdxxmdxdxds
kijkij xC
3
Λ2123
3,2,1, ji parameterize 3 out
6 dim to the D3-branes andKx denotes 3 spatial dim along
and five transverse to the D3-branes.
N
10-d IIB supergravity background
3D
PP-wave background
π 4ΓπΆπ 3
Matrix Inflation from String Theory
With9
Λ4Λ
222 sgm the above background with constant dilaton is solution to the SUGRA
22222
Λ2
1,
2.3
Λ, ,
24
1ikji
ijk
s
sjiji
s
XmXXXl
igXXXX
lV
23)2( ss
ii
lg
X
Upon the field redefinition
2
2
2 ,
3, ,
4Tr ijlkjkljiji
miV
sg 8 ss gg 8. Λ 22Λ mm
From the brane-theory perspective, it is necessary to choose mΜ and Μ such that
9
Λ4Λ
222 sgm
N D3-branes are blown up into a single giant D5-brane under the influence of RR 6-form. The inflaton corresponds to the radius of this two sphere.
Truncation to the SU(2) Sector:
i are N X N matrices and therefore we have 23N scalars. It makes the analysis very
difficult
However, one may show that there is a consistent classical truncation to a sector with single scalar field:
3,2,1 ,)(Λ iJt ii
iJ are N dim. irreducible representation of the SU(2) algebra:
kijkji JiJJ , ijji NN
JJ 112
Tr 2
Plugging these to the action, we have:
2
23424 Λ
2Λ
3
2Λ2
Λ Λ2
1Tr
2
m
JRM
gxdS P
ΛTr 2/1 2JDefining to make the kinetic term canonical, the potential takes the form
22
340 23
2
4)(
m
V effeff ,)1(
2
Tr ,
)1(
8
Tr
22222
NNJNNJ effeff
3
1
22 TrTri
iJJ
22eff )(4
)( Veff
2
m Hill-top or Symmetry-Breaking
inflation, Linde (1992)Lyth & Boubekeur (2005)
(a)
(b)
In the stringy picture, we have N D3-branes that are blown up into a giant D5-brane under the influence of RR 6-form.
(c)
1
4105N
Analysis of the Gauged M-flation around the Single-Block Vacuum
pM610
Mass Spectrum of Spectators
(a) -modes1- )1( 2N
2eff
2eff
2, )2( 2)3)(2(
2
1mlllM l
20 Nll Degeneracy of each
l-mode is 12 l
(b) -modes 1-)1( 2N
2eff
2eff
2, )1(2)1)(2(
2
1mlllM l
Nll 1 Degeneracy of each
l-mode is 12 l
(c) vector modes13 2 N
)1(4
22, llM efflA
modes
1)1( 2
N
modes
1)1( 2
N
modes field-vector
13 2 N 15 2 N
Degeneracy of each
l-mode is 12 l
πΟ2β
π»2
πππ2 ππ=
π π
ππ πππ (π)π β² (π)
=18(π¦βπ₯ )β π2
32ln(π
2+4 π¦π2+4 π₯ )
πβ‘12 (π
β²
π )2
=1 π₯=4πππ2 +πππ
ββ16πππ2 +2π2
ππβ1=2πβ6π|ππ
π¦πππ
2 =12+β144+8 (1βππ )π
2/πππ2
1βπππβ‘
πππ2 π β² β²
2π
(1)
(2)
(3)
Solving the model parameters based on Observables
Plugging (2) and (3) in (1) one can find solve in terms of numerically.
π΄π=π (π π)
24π 2 πππ4 π(π π)
β2.195Γ10β 9One can read off
(a) Symmetry-Breaking Region
From Planck experiment, within
For and π=0.1991β0.2 Right at the BICEP2 sweet spot
0.9457 β€ππβ€0.9749
However not all this interval is covered by this branch of the model!
Due to symmetry at the level of background these two regions predict the same
Hilltop Regions (b) and (c) & 2/
Symmetry breaks down at the quantum level.
2/0
β’ In region (b), the lightest mode is gauge mode
9.83Γ10β 4β²β’ In region (c), the lightest mode is mode
2 .84Γ10β4β² Around the isocurvature modes can act as preheat fields. The couplings of preheat fields to the inflaton are known.
at the peak frequency
Which can be observed at Chongqin HFGW detectoror Birmingham HFGW experiment.
Conclusions & Future Directions
β’ Matrix nature of the fields results in the production of isocurvature productions at the CMB scales.
β’ M-flation which is qualitatively new third venue within string theory inflationary model-building.
β’ M-flation solves the fine-tunings associated with chaotic inflation couplings.
β’ It produces super-Planckian effective field excursions from many individual sub-Planckian ones which yield large tensor/scalar ratio compatible with Planck.
β’ Due to hierarchical mass structure of the isocurvature modes, one can avoid the βbeyond-the-cutoffβ problem, exists in N-flation, even if
β’ M-flation has a natural built-in mechanism of preheating to end inflation around the vacuum which can produces large GHz frequency gravitational wave spectrum which could be seen by ultra-high frequency gravitational probes.
β’ The loop corrections from interactions of the graviton with the scalar field create the term if . In M-flation and many field models such induced terms is naturally suppressed. A.A., U.Danielsson, M. M. Sheikh-Jabbari, Phys.Lett. B713 (2012) 353, arXiv:1112.2272 [hep-th]
Conclusions & Future Directions
β’ Open Issue I: Reheating around the
β’ Open Issue II: Building a full-fledged stringy setup with all moduli fixed.