Inflation from tachyon condensation, largeNeffects

Abstract

Using only general properties of the tachyon potential we show that inflation may be generic when many branes and anti-branes become coincident. Inflation may occur because of: (1) the assistance of the many diagonal tachyon fields; (2) when the tachyons condense in a staggered fashion; or (3) when some of them condense very late. We point out that such inflation is in some sense a stringy implementation of chaotic inflation and may have important applications for "regularizing" a lopsided or singular cosmological compact surface.

Staggered multi-field inflation

“…One shortcoming, however, is the need for fine tuned initial conditions for particular potentials, especially in the absence of an attractor solution (for instance in N-flation [5]; see [6] for a more general stability analysis of assisted inflation). The presence of many degrees of freedom in string theory has, over the years, galvanized the emergence of a variety of models implementing assisted inflation; these include inflation from multiple tachyons [7], from multiple M5-branes within M-theory [8] or from axions [5] among others, see e.g. [9,10,11,12,13,14] for a small selection.…”

Exposition to Staggered Multi-Field Inflation

“…N , starting out from identical field values and with identical potentials V A ≡ V , such that assisted inflation [2] (slow roll inflation driven by many fields) results. If fields start to decay during inflation, for instance because they are related to branes that annihilate [3] or tachyons that condense [4], the number of fields decreases, causing a decrease of the energy driving inflation ρ I ≃ N V ≡ W . The energy in the just decayed field does not vanish, but gets converted into some other form ρ r , i.e.…”

“…Each tachyon sits close to the top of a hilltop-potential [4] and whenever a quantum mechanical fluctuation displaces a field, it condenses rapidly. If the fields are very close to the maximum, the slow roll contributions become negligible and one can use n s − 1 ≃ε(δ − 3).…”

“…For instructive purposes I would like to apply the formalism to the model of [4], where inflation is driven by N ∼ O(10 3 ) uncoupled tachyons (related to D-brane/antibrane pairs) that condense during inflation in a staggered fashion. Each tachyon sits close to the top of a hilltop-potential [4] and whenever a quantum mechanical fluctuation displaces a field, it condenses rapidly.…”

Preheating after Multi-Field Inflation

“…However, the presence of these resonances in multi-field models is largely unexplored, primarily because setups which employ hundreds of fields were proposed recently with the advent of more realistic scenarios of inflation within string theory; examples are inflation driven by axions as in N -flation [4], by tachyons [5] or by multiple M5-branes [6]. A challenge in many models is to prevent reheating of hidden sectors [7], but even if the inflatons are primarily coupled to standard model fields, little is known about the presence of resonances in setups with more than a few fields [3,8].…”