Closed strings in a class of pp-wave spacetimes and the memory effect

TL;DR

This paper investigates how gravitational wave pulses in pp-wave spacetimes cause permanent deformations in closed strings and their worldsheet geometry, revealing a string-theoretic memory effect.

Contribution

It demonstrates that gravitational wave pulses induce permanent deformations in closed strings and their worldsheet geometry, linking string dynamics to gravitational wave memory effects.

Findings

Circular closed strings deform permanently after pulse passage

Worldsheet geometry exhibits lasting changes due to gravitational waves

Memory effects are observed in string and worldsheet structures

Abstract

We study closed string evolution in the pp-wave spacetime assuming different pulse shapes (square and sech-squared) in the exact gravitational wave metric. It is shown that the shape of a circular closed string deforms permanently, after the pulse has departed. The worldsheet geometry also displays characteristic permanent changes caused by the gravitational wave pulse. The above effects collectively demonstrate features akin to what is known as `memory' in gravitational wave physics.