Abstract
Inflationary scenarios in string theory often involve a large number of light scalar fields, whose presence can enrich the post-inflationary evolution of primordial fluctuations generated during the inflationary epoch. We provide a simple example of such post-inflationary processing within an explicit string-inflationary construction, using a Kähler modulus as the inflaton within the framework of LARGE Volume Type-IIB string flux compactifications. We argue that inflationary models within this broad category often have a selection of scalars that are light enough to be cosmologically relevant, whose contributions to the primordial fluctuation spectrum can compete with those generated in the standard way by the inflaton. These models consequently often predict nongaussianity at a level, \( {f_{\text{NL}}} \simeq \mathcal{O}\left( {10} \right) \), potentially observable by the Planck satellite, with a bi-spectrum maximized by triangles with squeezed shape in a string realization of the curvaton scenario. We argue that the observation of such a signal would robustly prefer string cosmologies such as these that predict a multi-field dynamics during the very early universe.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
WMAP collaboration, E. Komatsu et al., Five-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: cosmological interpretation, Astrophys. J. Suppl. 180 (2009) 330 [arXiv:0803.0547] [SPIRES].
SDSS collaboration, M. Tegmark et al., Cosmological parameters from SDSS and WMAP, Phys. Rev. D 69 (2004) 103501 [astro-ph/0310723] [SPIRES].
A.H. Guth, The inflationary universe: a possible solution to the horizon and flatness problems, Phys. Rev. D 23 (1981) 347 [SPIRES].
A.D. Linde, A new inflationary universe scenario: a possible solution of the horizon, flatness, homogeneity, isotropy and primordial monopole problems, Phys. Lett. B 108 (1982) 389 [SPIRES].
A. Albrecht and P.J. Steinhardt, Cosmology for grand unified theories with radiatively induced symmetry breaking, Phys. Rev. Lett. 48 (1982) 1220 [SPIRES].
G.R. Dvali and S.H. Henry Tye, Brane inflation, Phys. Lett. B 450 (1999) 72 [hep-ph/9812483] [SPIRES].
C. Herdeiro, S. Hirano and R. Kallosh, String theory and hybrid inflation/acceleration, JHEP 12 (2001) 027 [hep-th/0110271] [SPIRES].
J. García-Bellido, R. Rabadán and F. Zamora, Inflationary scenarios from branes at angles, JHEP 01 (2002) 036 [hep-th/0112147] [SPIRES].
K. Dasgupta, C. Herdeiro, S. Hirano and R. Kallosh, D3/D7 inflationary model and M-theory, Phys. Rev. D 65 (2002) 126002 [hep-th/0203019] [SPIRES].
N.T. Jones, H. Stoica and S.H. Henry Tye, Brane interaction as the origin of inflation, JHEP 07 (2002) 051 [hep-th/0203163] [SPIRES].
M. Gómez-Reino and I. Zavala, Recombination of intersecting D-branes and cosmological inflation, JHEP 09 (2002) 020 [hep-th/0207278] [SPIRES].
J.P. Hsu, R. Kallosh and S. Prokushkin, On brane inflation with volume stabilization, JCAP 12 (2003) 009 [hep-th/0311077] [SPIRES].
F. Koyama, Y. Tachikawa and T. Watari, Supergravity analysis of hybrid inflation model from D3-D7 system, Phys. Rev. D 69 (2004) 106001 [Erratum ibid. D 70 (2004) 129907] [hep-th/0311191] [SPIRES].
J.P. Hsu and R. Kallosh, Volume stabilization and the origin of the inflaton shift symmetry in string theory, JHEP 04 (2004) 042 [hep-th/0402047] [SPIRES].
K. Dasgupta, J.P. Hsu, R. Kallosh, A.D. Linde and M. Zagermann, D3/D7 brane inflation and semilocal strings, JHEP 08 (2004) 030 [hep-th/0405247] [SPIRES].
P. Chen, K. Dasgupta, K. Narayan, M. Shmakova and M. Zagermann, Brane inflation, solitons and cosmological solutions: I, JHEP 09 (2005) 009 [hep-th/0501185] [SPIRES].
L. McAllister, An inflaton mass problem in string inflation from threshold corrections to volume stabilization, JCAP 02 (2006) 010 [hep-th/0502001] [SPIRES].
M. Haack et al., Update of D3/D7-Brane Inflation on K3 × T 2 /Z 2, Nucl. Phys. B 806 (2009) 103 [arXiv:0804.3961] [SPIRES].
C.P. Burgess, J.M. Cline and M. Postma, Axionic D3-D7 inflation, JHEP 03 (2009) 058 [arXiv:0811.1503] [SPIRES].
C.P. Burgess et al., The inflationary brane-antibrane universe, JHEP 07 (2001) 047 [hep-th/0105204] [SPIRES].
G.R. Dvali, Q. Shafi and S. Solganik, D-brane inflation, hep-th/0105203 [SPIRES].
C.P. Burgess, P. Martineau, F. Quevedo, G. Rajesh and R.J. Zhang, Brane antibrane inflation in orbifold and orientifold models, JHEP 03 (2002) 052 [hep-th/0111025] [SPIRES].
S. Kachru et al., Towards inflation in string theory, JCAP 10 (2003) 013 [hep-th/0308055] [SPIRES].
H. Firouzjahi and S.H. Henry Tye, Closer towards inflation in string theory, Phys. Lett. B 584 (2004) 147 [hep-th/0312020] [SPIRES].
S.E. Shandera and S.H. Henry Tye, Observing brane inflation, JCAP 05 (2006) 007 [hep-th/0601099] [SPIRES].
D. Baumann, A. Dymarsky, I.R. Klebanov and L. McAllister, Towards an explicit model of D-brane inflation, JCAP 01 (2008) 024 [arXiv:0706.0360] [SPIRES].
A. Avgoustidis, D. Cremades and F. Quevedo, Wilson line inflation, Gen. Rel. Grav. 39 (2007) 1203 [hep-th/0606031] [SPIRES].
A. Avgoustidis and I. Zavala, Warped Wilson line DBI inflation, JCAP 01 (2009) 045 [arXiv:0810.5001] [SPIRES].
J.J. Blanco-Pillado et al., Racetrack inflation, JHEP 11 (2004) 063 [hep-th/0406230] [SPIRES].
Z. Lalak, G.G. Ross and S. Sarkar, Racetrack inflation and assisted moduli stabilisation, Nucl. Phys. B 766 (2007) 1 [hep-th/0503178] [SPIRES].
B. Greene and A. Weltman, An effect of α′ corrections on racetrack inflation, JHEP 03 (2006) 035 [hep-th/0512135] [SPIRES].
J.J. Blanco-P illado et al., Inflating in a better racetrack, JHEP 09 (2006) 002 [hep-th/0603129] [SPIRES].
H.-Y. Chen, L.-Y. Hung and G. Shiu, Inflation on an open racetrack, JHEP 03 (2009) 083 [arXiv:0901.0267] [SPIRES].
A.D. Linde, Inflation and string cosmology, eConf C 040802 (2004) L024 [J. Phys. Conf. Ser. 24 (2005) 151] [ hep-th/0503195 ] [Prog. Theor. Phys. Suppl. 163 (2006) 295] [ SPIRES].
F. Quevedo, Lectures on string/brane cosmology, Class. Quant. Grav. 19 (2002) 5721 [hep-th/0210292] [SPIRES].
F. Quevedo, The standard model and inflation from string theory, AIP Conf. Proc. 743 (2005) 341 [SPIRES].
S.H. Henry Tye, Brane inflation: string theory viewed from the cosmos, Lect. Notes Phys. 737 (2008) 949 [hep-th/0610221] [SPIRES].
J.M. Cline, String cosmology, hep-th/0612129 [SPIRES].
R. Kallosh, On inflation in string theory, Lect. Notes Phys. 738 (2008) 119 [hep-th/0702059] [SPIRES].
L. McAllister and E. Silverstein, String cosmology: a review, Gen. Rel. Grav. 40 (2008) 565 [arXiv:0710.2951] [SPIRES].
D. Baumann, TA SI lectures on inflation, arXiv:0907.5424 [SPIRES].
C.P. Burgess, Lectures on cosmic inflation and its potential stringy realizations, PoS(P2GC)008 [PoS(CARGESE)003] [Class. Quant. Grav. 24 (2007) S795] [arXiv:0708.2865] [SPIRES].
P. Brax, S.C. Davis and M. Postma, The robustness of n s < 0.95 in racetrack inflation, JCAP 02 (2008) 020 [arXiv:0712.0535] [SPIRES].
E.I. Buchbinder, J. Khoury and B.A. Ovrut, Non-Gaussianities in new ekpyrotic cosmology, Phys. Rev. Lett. 100 (2008) 171302 [arXiv:0710.5172] [SPIRES].
M. Gasperini and G. Veneziano, Pre-big bang in string cosmology, Astropart. Phys. 1 (1993) 317 [hep-th/9211021] [SPIRES].
C. Angelantonj, L. Amendola, M. Litterio and F. Occhionero, String cosmology and inflation, Phys. Rev. D 51 (1995) 1607 [astro-ph/9501008] [SPIRES].
J. Khoury, B.A. Ovrut, P.J. Steinhardt and N. Turok, The ekpyrotic universe: colliding branes and the origin of the hot big bang, Phys. Rev. D 64 (2001) 123522 [hep-th/0103239] [SPIRES].
P.J. Steinhardt and N. Turok, Cosmic evolution in a cyclic universe, Phys. Rev. D 65 (2002) 126003 [hep-th/0111098] [SPIRES].
R. Kallosh, L. Kofman and A.D. Linde, Pyrotechnic universe, Phys. Rev. D 64 (2001) 123523 [hep-th/0104073] [SPIRES].
L. Kofman, A.D. Linde and V.F. Mukhanov, Inflationary theory and alternative cosmology, JHEP 10 (2002) 057 [hep-th/0206088] [SPIRES].
R.H. Brandenberger, A. Nayeri, S.P. Patil and C. Vafa, String gas cosmology and structure formation, Int. J. Mod. Phys. A 22 (2007) 3621 [hep-th/0608121] [SPIRES].
N. Kaloper, L. Kofman, A.D. Linde and V. Mukhanov, On the new string theory inspired mechanism of generation of cosmological perturbations, JCAP 10 (2006) 006 [hep-th/0608200] [SPIRES].
H.-Y. Chen, J.-O. Gong and G. Shiu, Systematics of multi-field effects at the end of warped brane inflation, JHEP 09 (2008) 011 [arXiv:0807.1927] [SPIRES].
R. Flauger, L. McAllister, E. Pajer, A. Westphal and G. Xu, Oscillations in the CMB from axion monodromy inflation, JCAP 06 (2010) 009 [arXiv:0907.2916] [SPIRES].
R. Flauger and E. Pajer, Resonant nongaussianity, arXiv:1002.0833 [SPIRES].
D.H. Lyth and D. Wands, Generating the curvature perturbation without an inflaton, Phys. Lett. B 524 (2002) 5 [hep-ph/0110002] [SPIRES].
T. Moroi and T. Takahashi, Effects of cosmological moduli fields on cosmic microwave background, Phys. Lett. B 522 (2001) 215 [Erratum ibid. B 539 (2002) 303] [hep-ph/0110096] [SPIRES].
K. Enqvist and M.S. Sloth, Adiabatic CMB perturbations in pre big bang string cosmology, Nucl. Phys. B 626 (2002) 395 [hep-ph/0109214] [SPIRES].
G. Dvali, A. Gruzinov and M. Zaldarriaga, A new mechanism for generating density perturbations from inflation, Phys. Rev. D 69 (2004) 023505 [astro-ph/0303591] [SPIRES].
G. Dvali, A. Gruzinov and M. Zaldarriaga, Cosmological perturbations from inhomogeneous reheating, freezeout and mass domination, Phys. Rev. D 69 (2004) 083505 [astro-ph/0305548] [SPIRES].
L. Kofman, Probing string theory with modulated cosmological fluctuations, astro-ph/0303614 [SPIRES].
M. Zaldarriaga, Non-Gaussianities in models with a varying inflaton decay rate, Phys. Rev. D 69 (2004) 043508 [astro-ph/0306006] [SPIRES].
S. Sarangi and S.H. Henry Tye, Cosmic string production towards the end of brane inflation, Phys. Lett. B 536 (2002) 185 [hep-th/0204074] [SPIRES].
E.J. Copeland, R.C. Myers and J. Polchinski, Cosmic F-and D-strings, JHEP 06 (2004) 013 [hep-th/0312067] [SPIRES].
T. Matsuda, String production after angled brane inflation, Phys. Rev. D 70 (2004) 023502 [hep-ph/0403092] [SPIRES].
H. Firouzjahi and S.H. Henry Tye, Brane inflation and cosmic string tension in superstring theory, JCAP 03 (2005) 009 [hep-th/0501099] [SPIRES].
N. Barnaby, C.P. Burgess and J.M. Cline, Warped reheating in brane-antibrane inflation, JCAP 04 (2005) 007 [hep-th/0412040] [SPIRES].
A.R. Frey, A. Mazumdar and R.C. Myers, Stringy effects during inflation and reheating, Phys. Rev. D 73 (2006) 026003 [hep-th/0508139] [SPIRES].
L. Kofman and P. Yi, Reheating the universe after string theory inflation, Phys. Rev. D 72 (2005) 106001 [hep-th/0507257] [SPIRES].
D. Chialva, G. Shiu and B. Underwood, Warped reheating in multi-throat brane inflation, JHEP 01 (2006) 014 [hep-th/0508229] [SPIRES].
X. Chen and S.H. Henry Tye, Heating in brane inflation and hidden dark matter, JCAP 06 (2006) 011 [hep-th/0602136] [SPIRES].
P. Langfelder, On tunnelling in two-throat warped reheating, JHEP 06 (2006) 063 [hep-th/0602296] [SPIRES].
M. Cicoli and A. Mazumdar, Reheating for closed string inflation, arXiv:1005.5076 [SPIRES].
C.P. Burgess, J.M. Cline, H. Stoica and F. Quevedo, Inflation in realistic D-brane models, JHEP 09 (2004) 033 [hep-th/0403119] [SPIRES].
R. Kallosh and A.D. Linde, Landscape, the scale of SUSY breaking and inflation, JHEP 12 (2004) 004 [hep-th/0411011] [SPIRES].
J.J. Blanco-Pillado, R. Kallosh and A.D. Linde, Supersymmetry and stability of flux vacua, JHEP 05 (2006) 053 [hep-th/0511042] [SPIRES].
R. Kallosh and A.D. Linde, O’KKLT, JHEP 02 (2007) 002 [hep-th/0611183] [SPIRES].
M. Liguori, E. Sefusatti, J.R. Fergusson and E.P.S. Shellard, Primordial nongaussianity and bispectrum measurements in the cosmic microwave background and large-scale structure, arXiv:1001.4707 [SPIRES].
V. Balasubramanian, P. Berglund, J.P. Conlon and F. Quevedo, Systematics of moduli stabilisation in Calabi-Yau flux compactifications, JHEP 03 (2005) 007 [hep-th/0502058] [SPIRES].
J.P. Conlon, F. Quevedo and K. Suruliz, Large-volume flux compactifications: moduli spectrum and D3/D7 soft supersymmetry breaking, JHEP 08 (2005) 007 [hep-th/0505076] [SPIRES].
J.P. Conlon and F. Quevedo, Astrophysical and cosmological implications of large volume string compactifications, JCAP 08 (2007) 019 [arXiv:0705.3460] [SPIRES].
M. Cicoli, J.P. Conlon and F. Quevedo, General analysis of LARGE volume scenarios with string loop moduli stabilisation, JHEP 10 (2008) 105 [arXiv:0805.1029] [SPIRES].
C.P. Burgess, A. Maharana and F. Quevedo, Über-naturalness: unexpectedly light scalars from supersymmetric extra dimensions, arXiv:1005.1199 [SPIRES].
L. Anguelova, V. Calo and M. Cicoli, LARGE volume string compactifications at finite temperature, JCAP 10 (2009) 025 [arXiv:0904.0051] [SPIRES].
J.P. Conlon and F. Quevedo, Kähler moduli inflation, JHEP 01 (2006) 146 [hep-th/0509012] [SPIRES].
J. Simon, R. J imenez, L. Verde, P. Berglund and V. Balasubramanian, Using cosmology to constrain the topology of hidden dimensions, astro-ph/0605371 [SPIRES].
J.R. Bond, L. Kofman, S. Prokushkin and P.M. Vaudrevange, Roulette inflation with Kähler moduli and their axions, Phys. Rev. D 75 (2007) 123511 [hep-th/0612197] [SPIRES].
V. Balasubramanian, P. Berglund, R. Jimenez, J. Simon and L. Verde, Topology from cosmology, JHEP 06 (2008) 025 [arXiv:0712.1815] [SPIRES].
J.J. Blanco-Pillado, D. Buck, E.J. Copeland, M. Gómez-Reino and N.J. Nunes, Kähler moduli inflation revisited, JHEP 01 (2010) 081 [arXiv:0906.3711] [SPIRES].
M. Cicoli, C.P. Burgess and F. Quevedo, Fibre inflation: observable gravity waves from IIB string compactifications, JCAP 03 (2009) 013 [arXiv:0808.0691] [SPIRES].
P. Berglund and G. Ren, Multi-field inflation from string theory, arXiv:0912.1397 [SPIRES].
R. Blumenhagen, S. Moster and E. Plauschinn, Moduli stabilisation versus chirality for MSSM like type IIB orientifolds, JHEP 01 (2008) 058 [arXiv:0711.3389] [SPIRES].
M. Berg, M. Haack and B. Körs, String loop corrections to Kähler potentials in orientifolds, JHEP 11 (2005) 030 [hep-th/0508043] [SPIRES].
M. Berg, M. Haack and E. Pajer, Jumping through loops: on soft terms from large volume compactifications, JHEP 09 (2007) 031 [arXiv:0704.0737] [SPIRES].
M. Cicoli, J.P. Conlon and F. Quevedo, Systematics of string loop corrections in type IIB Calabi-Yau flux compactifications, JHEP 01 (2008) 052 [arXiv:0708.1873] [SPIRES].
R. Blumenhagen, J.P. Conlon, S. Krippendorf, S. Moster and F. Quevedo, SUSY breaking in local string/F-theory models, JHEP 09 (2009) 007 [arXiv:0906.3297] [SPIRES].
M. Cicoli, M. Kreuzer and C. Mayerhofer, Moduli stabilisation for GUT scenarios in explicit compact Calabi-Yau constructions, in preparation.
K. Dimopoulos, G. Lazarides, D. Lyth and R. Ruiz de Austri, Curvaton dynamics, Phys. Rev. D 68 (2003) 123515 [hep-ph/0308015] [SPIRES].
Q.-G. Huang, Large nongaussianity implication for curvaton scenario, Phys. Lett. B 669 (2008) 260 [arXiv:0801.0467] [SPIRES].
D.H. Lyth, C. Ungarelli and D. Wands, The primordial density perturbation in the curvaton scenario, Phys. Rev. D 67 (2003) 023503 [astro-ph/0208055] [SPIRES].
D. Wands, Local nongaussianity from inflation, Class. Quant. Grav. 27 (2010) 124002 [arXiv:1004.0818] [SPIRES].
E. Komatsu et al., Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) observations: cosmological interpretation, arXiv:1001.4538 [SPIRES].
J. Smidt et al., A measurement of cubic-order primordial nongaussianity (g NL and τ NL ) with WMAP 5-year data, arXiv:1001.5026 [SPIRES].
C.T. Byrnes and G. Tasinato, Nongaussianity beyond slow roll in multi-field inflation, JCAP 08 (2009) 016 [arXiv:0906.0767] [SPIRES].
C.T. Byrnes, S. Nurmi, G. Tasinato and D. Wands, Scale dependence of local f NL, JCAP 02 (2010) 034 [arXiv:0911.2780] [SPIRES].
N. Barnaby, J.R. Bond, Z. Huang and L. Kofman, Preheating after modular inflation, JCAP 12 (2009) 021 [arXiv:0909.0503] [SPIRES].
M.Y. Khlopov, Primordial black holes, Res. Astron. Astrophys. 10 (2010) 495 [arXiv:0801.0116] [SPIRES].
Author information
Authors and Affiliations
Corresponding author
Additional information
Dedicated to Lev Kofman, whose untimely passing makes the Universe a little bit darker.
Rights and permissions
Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
About this article
Cite this article
Burgess, C.P., Cicoli, M., Gómez-Reino, M. et al. Non-standard primordial fluctuations and nongaussianity in string inflation. J. High Energ. Phys. 2010, 45 (2010). https://doi.org/10.1007/JHEP08(2010)045
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP08(2010)045