Ultrarelativistic boost with scalar field

TL;DR

This paper investigates the ultrarelativistic boost of a global monopole solution and a scalar field, revealing that scalar fields tend to vanish in the boosting limit across symmetric scenarios.

Contribution

It introduces a detailed analysis of the ultrarelativistic boost of global monopoles and scalar fields, highlighting the scalar field behavior during high-velocity limits.

Findings

Scalar fields vanish in the ultrarelativistic boost limit.

The metric tensor and energy-momentum tensor approaches yield consistent results.

Scalar fields in symmetric solutions tend to disappear under extreme boosts.

Abstract

We present the ultrarelativistic boost of the general global monopole solution which is parametrized by mass and deficit solid angle. The problem is addressed from two different perspectives. In the first one the primary object for performing the boost is the metric tensor while in the second one the energy momentum tensor is used. Since the solution is sourced by a triplet of scalar fields that effectively vanish in the boosting limit we investigate the behavior of a scalar field in a simpler setup. Namely, we perform the boosting study of the spherically symmetric solution with a free scalar field given by Janis, Newman and Winicour. The scalar field is again vanishing in the limit pointing to a broader pattern of scalar field behaviour during an ultrarelativistic boost in highly symmetric situations.