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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We consider the N=4 SYM theory in flat 3+1 dimensional spacetime with a timedependent coupling constant which vanishes at $t=0$, like $g_{YM}^2=t^p$. In ananalogous quantum mechanics toy model we find that the response is singular.The energy diverges at $t=0$, for a generic state. In addition, if $p>1$ thephase of the wave function has a wildly oscillating behavior, which does notallow it to be continued past $t=0$. A similar effect would make the gaugetheory singular as well, though nontrivial effects of renormalization couldtame this singularity and allow a smooth continuation beyond $t=0$. The gravitydual in some cases is known to be a time dependent cosmology which exhibits aspace-like singularity at $t=0$. Our results, if applicable in the gauge theoryfor the case of the vanishing coupling, imply that the singularity is a genuinesickness and does not admit a meaningful continuation. When the couplingremains non-zero and becomes small at $t=0$, the curvature in the bulk becomesof order the string scale. The gauge theory now admits a time evolution beyondthis point. In this case, a finite amount of energy is produced which possiblythermalizes and leads to a black hole in the bulk.

Gauge Theories with Time Dependent Couplings and their Cosmological Duals