English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We point out that quintessence with an exponential potential V_0 exp(- betaphi / 3^{1/2} M_p) can account for the present observed acceleration of theuniverse, without necessarily leading to eternal acceleration. This occurs for2.4 < beta < 2.8. Thus a cosmological horizon, which is supposed to beproblematic within the context of string theory, can be avoided. We argue thatthis class of models is not particularly fine-tuned. We further examine thisquestion in the context of a modified Friedmann equation, H^2 ~ rho + p, whichis suggested by higher dimensional self-tuning approaches to the cosmologicalconstant problem. It is shown that the self-tuning case can also be consistentwith observations, if 1.8 < beta < 2.4. Future observations of high-zsupernovae will be able to test whether beta lies in the desired range.Comment: 13 pp., 5 figures; references adde

Quintessence, cosmological horizons, and self-tuning