Recurrent Acceleration in Dilaton - Axion Cosmology

نویسنده

  • Paul K. Townsend
چکیده

A class of Einstein-dilaton-axion models is found for which almost all flat expanding homogeneous and isotropic universes undergo recurrent periods of acceleration. We also extend recent results on eternally accelerating open universes.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Axion–Dilaton Cosmology and Dark Energy

We discuss a class of flat FRW cosmological models based on D=4 axion-dilaton gravity universally coupled to cosmological background fluids. In particular, we investigate the possibility of recurrent acceleration, which was recently shown to be generically realized in a wide class of axion-dilaton models, but in absence of cosmological background fluids. We observe that, once we impose the exis...

متن کامل

A Note on Brans-Dicke Cosmology with Axion

We study the Brans-Dicke model in the presence of an axion. The dynamical equations are solved when the fields are space independent and the metric is spatially flat. It is found that at late time the scale factor undergoes decelerated expansion but the dilaton grows large. At early time, scale factor and the dilaton approach constants.

متن کامل

Axion Cosmology with its Scalar Superpartner

In supersymmetric theories, the Peccei-Quinn symmetry has a complex extension as a symmetry of the superpotential, so that the scalar potential always has an almost flat direction, the dilaton. We discuss how coherent oscillation of the dilaton affects axion cosmology. We stress that the dilaton decay, if its dominant mode is not into axions, releases large entropy at a late epoch of the Univer...

متن کامل

S-duality invariant perturbations in string cosmology

We investigate the generation of curvature and isocurvature (dilaton, moduli and axion) perturbations in a general class of axion–dilaton–moduli models, including the pre–big bang scenario. Allowing for an arbitrary coupling constant λ between the dilaton field and the axion field, we exploit the SL(2,R) symmetry of the theory to obtain the spectral indices of the field perturbations in a pre–b...

متن کامل

Vacuum fluctuations in axion-dilaton cosmologies

We study axion-dilaton cosmologies derived from the low-energy string effective action. We present the classical homogeneous Friedmann-Robertson-Walker solutions and derive the semiclassical perturbation spectra in the dilaton, axion, and moduli fields in the pre-big-bang scenario. By constructing the unique S-duality-invariant field perturbations for the axion and dilaton fields we derive S-du...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2006