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Warm inflation in small field models:
a stringy realisation
Juan Carlos Bueno Sánchez
Lancaster University
Work in progress with: M. Bastero-Gil (University of Granada), A. Berera (University of Edinburgh) and K. Dimopoulos (Lancaster University)
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Radiation production after inflation
Inflaton may lose energy non-perturbatively (preheating: non-linear effects )
Weak dissipation:
Strong dissipation:
Inflaton EOM
Cold inflation
Introduction
InflatondecayRadiation density
(production of radiation during inflation)Warm inflation
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Equilibrium approach Radiation is close to thermal equilibrium
Moss and Xiong ‘07
Warm inflation is very difficult
Inflaton may lose energy as well
High T:
Low T:
Yokoyama and Linde ‘99
Chaotic and Hybrid models Bastero-Gil and Berera ‘06
Warm inflation supported for ~ 50-60 e-folds
X and Y may belong to large rep. of GUT group
with
Introduction
Dissipation mechanism:
Allowed decays
with
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Take inverted potential
A small field model
Take inflation gives way to radiation domination
before
Weak dissipation
Strong dissipation (with )
Dissipation coefficient
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Warm inflation Radiation domination
Inflation after horizon exit
Spectrum curvature perturbations
Spectral index
Matching the spectrum
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Warm inflation in string theory
ESP
Fixed point of symmetries
Trapping mechanism (particle production)
Moduli trapping
Why an enhanced symmetry point?
mP
Strong interaction between and
Naturalness of the trapping
prefers points with higher number of fields
Trapping operates at distances
Inflaton is a string modulus passing close to an enhanced symmetry point
Environmental selection of larger
ESPs typically at Planckian distance
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Warm inflation in string theory
ESP
Fixed point of symmetries
Trapping mechanism (particle production)
Moduli trapping
Why an enhanced symmetry point?
Strong interaction between and
Naturalness of the trapping
prefers points with higher number of fields
Trapping operates at distances
Environmental selection of larger
ESPs typically at Planckian distance
Environmental selection makes easier to fit the spectrum
Inflaton is a string modulus passing close to an enhanced symmetry point
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gives its oscillation density no overshoot
Decay of before inflation
Decay of during inflation no overshoot
Warm inflation in string theory
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Decay of before inflation
and
may overshoot the ESP
h is larger but far from its maximum value
Warm inflation in string theory
![Page 10: Warm inflation in small field models: a stringy realisation Juan Carlos Bueno Sánchez Lancaster University Work in progress with: M. Bastero-Gil (University](https://reader033.vdocument.in/reader033/viewer/2022051618/56649ceb5503460f949b6ccc/html5/thumbnails/10.jpg)
Decay of before inflation
and
may overshoot the ESP
h is larger but far from its maximum value
Warm inflation in string theory
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Decay of before inflation
and
may overshoot the ESP
h is larger but far from its maximum value
Warm inflation in string theory
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Decay of before inflation
and
may overshoot the ESP
h is larger but far from its maximum value
Warm inflation in string theory
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Conclusions
Full analytical description of inflation in the low-temperature regime.
Inflation may finish in weak dissipation, retaining a constant radiation density which may reheat the Universe.
Inflation may give way to radiation dominated Universe.
Spectral index may be fitted to the observational values by tunning H
The observed spectrum may be matched for a wide range of curvatures In particular for
String theory (modulus + ESP) may fix initial conditions for warm inflation
Initial radiation bath from decay products
Strong interaction between fields
Trapping provides environmental selection mechanism making easier fit spectrum