Crunching Away the Cosmological Constant Problem: Dynamical Selection of a Small Lambda

  Itay Bloch [1]  ,  Csaba Csaki [2]  ,  Michael Geller [1]  ,  Tomer Volansky [1]  
[1] School of Physics and Astronomy, Tel-Aviv University.
[2] Department of Physics, LEPP, Cornell University.

I will discuss a novel explanation for the smallness of the observed cosmological constant (CC). Regions of space with a large CC are short lived and are dynamically driven to crunch soon after the end of inflation. Conversely, regions with a small CC are metastable and long lived and are the only ones to survive until late times. While the mechanism assumes many domains with different CC values, it does not result in eternal inflation nor does it require a long period of inflation to populate them. The mechanism can only solve the CC problem up to the weak scale, above which new physics, such as supersymmetry, is needed to solve the CC problem all the way to the UV cutoff scale. Curiously, in this approach the weak scale arises as the geometric mean of the temperature in our universe today and the Planck scale, hinting on a new "CC miracle", motivating new physics at the weak scale independent of electroweak physics. The model also predicts the presence of new relativistic degrees of freedom in the CFT that should be visible in the next round of CMB experiments. The mechanism is therefore experimentally falsifiable and predictive.