& lead Physics 17, s78
Theorists explain why cosmic inflation may appear to be driven by a single inflaton field, even if it was actually driven by two or more such fields.
Cosmic inflation—a theorized exponential expansion of space in the early Universe—provides solutions to important cosmological puzzles. It explains why the Universe appears perfectly flat: expansion stretches any curvature to the point of invisibility. It also explains how quantum fluctuations of the vacuum can become seeds for the structure of the Universe. Most models of physics beyond the Standard Model include many new quantum fields, suggesting that inflation could have been driven by multiple fields. However, observations of the cosmic microwave background radiation favor that there is only one such “inflaton” field. So are multifield models inconsistent with observations?
Now Koki Tokeshi of the University of Tokyo and Vincent Vennin of the Sorbonne University, France, propose an explanation for the emergence of a single field dominating inflation [1]. The researchers consider an inflation model that includes two inflaton fields whose quantum fluctuations make their dynamics stochastic. In each microscopic part of space, the fields evolve stochastically until inflation ends. Using a previously developed test [2], the pair calculate that, in that part, this evolution can cause the lighter field (the one associated with a smaller “mass parameter”) to dominate over the other. Thus, inflation in that part can be well approximated by a single-field theory.
But how common are parts of the Universe suitable for such evolution? Tokeshi and Vennin show that patches with suitable initial conditions correspond to regions of spacetime that undergo more inflation and thus end up having larger volumes. As a result, two-field inflation can look like one-field inflation, because these regions make up most of the volume of the Universe. The researchers say they expect similar results to hold for the case of more than two domains.
– Robert Garisto
Robert Garisto is the Managing Editor of Physical review papers.
References
- K. Tokeshi and V. Vennin, “Why does inflation seem like a single field?” Phys. Rev. Latvian. 132251001 (2024).
- CM Peterson and M. Tegmark, “Testing Two-Area Inflation,” Phys. Rev. D 83023522 (2011).
Subject areas
#field #rule
Image Source : physics.aps.org
