Critical Collapse of a Scalar Field in Semiclassical Loop Quantum Gravity

Area of Science:

• * Theoretical physics, specifically focusing on quantum gravity and general relativity.
• * Investigating the behavior of scalar fields under gravitational collapse.

Background:

• * Classical general relativity predicts critical phenomena during gravitational collapse, as demonstrated by Choptuik.
• * Loop quantum gravity offers a framework for quantum gravity, with implications for phenomena like gravitational collapse.

Purpose of the Study:

• * To investigate the collapse of a massless scalar field in spherical symmetry using semiclassical loop quantum gravity equations.
• * To determine if quantum gravity effects alter the critical behavior observed in classical general relativity.

Main Methods:

• * Utilized semiclassical equations derived from loop quantum gravity.
• * Studied the collapse of a massless scalar field minimally coupled to gravity.
• * Analyzed a wide range of initial data and polymerization parameter values.

Main Results:

• * Observed critical behavior in the mass as a function of initial data parameters, consistent with classical findings.
• * Discovered that the semiclassical field equations exhibit exact scale invariance, similar to classical equations.
• * Numerically confirmed a second-order phase transition, mirroring the classical case.

Conclusions:

• * Semiclassical loop quantum gravity reproduces classical critical phenomena in gravitational collapse.
• * The presence of exact scale invariance in quantum gravity equations challenges prior expectations.
• * The phase transition remains second order, aligning with classical general relativity predictions.