[Paper Review] Schwinger Effect in String Theory

Constantin P. Bachas|ArXiv.org|Mar 10, 1993

Computational Physics and Python Applications3 citations

TL;DR

This paper investigates the Schwinger effect—pair production in strong electric fields—within the framework of open string theory. Using string perturbation theory, Bachas computes the imaginary part of the effective action, demonstrating that electric fields induce pair production via open string creation, with the rate matching the known QED result in the weak-field limit.

ABSTRACT

I discuss the quantum instability of an electric field in a theory of open strings.

Motivation & Objective

• To study the quantum instability of an electric field in a theory of open strings.
• To understand how pair production arises in string theory due to strong electric fields.
• To compute the imaginary part of the effective action, signaling vacuum decay via pair production.
• To verify consistency with the known Schwinger effect in quantum field theory in the weak-field limit.
• To explore the role of open strings in describing vacuum decay in external electric fields.

Proposed method

• Analyzes the effective action of open string theory in the presence of a constant electric field.
• Applies string perturbation theory to compute the imaginary part of the partition function.
• Uses the optical theorem to relate the imaginary part to the pair production rate.
• Treats the electric field as a background gauge field coupled to open strings on D-branes.
• Performs calculations in the low-energy limit, focusing on the tachyon and vector modes.
• Compares the result to the standard Schwinger formula in QED for consistency.

Experimental results

Research questions

• RQ1 How does the Schwinger effect manifest in open string theory?
• RQ2 What is the rate of pair production in a strong electric field within string theory?
• RQ3 Does the string-theoretic computation reproduce the known QED result for weak electric fields?
• RQ4 What role do D-branes and open string modes play in the vacuum decay process?
• RQ5 How does the imaginary part of the effective action relate to pair production in string theory?

Key findings

• The imaginary part of the effective action in open string theory with a constant electric field is non-zero, signaling vacuum instability.
• The pair production rate computed via string theory matches the standard Schwinger formula in the weak-field limit.
• The result is derived from the one-loop partition function of open strings in a constant electric field background.
• The mechanism is consistent with pair creation via open string states, particularly involving tachyon and gauge modes.
• The calculation confirms that string theory correctly reproduces the non-perturbative Schwinger effect in the low-energy limit.
• The analysis provides a string-theoretic derivation of the Schwinger effect, bridging quantum field theory and string dynamics.