[Paper Review] Negative coupling instability and grandunified baryogenesis

Tomislav Prokopec|ArXiv.org|Aug 22, 1997

Cosmology and Gravitation Theories3 citations

TL;DR

This paper introduces the negative coupling instability in two-scalar-field models, demonstrating that a negative cross-coupling term triggers explosive particle production and ultrafast inflaton decay. The instability enables efficient baryogenesis in grand unified theories by enhancing non-thermal baryon number violation during rapid field evolution, offering a novel mechanism for generating the matter-antimatter asymmetry.

ABSTRACT

I review my recent work with Brian Greene and Thomas Roos. First I discuss the effect of a negative cross-coupling on the inflaton decay in two scalar field theories. Our main finding is a new effect, the negative coupling instability, which leads to explosive particle production and very fast inflaton decay. Then I discuss the consequences of this instability for grandunified baryogenesis models. The novel aspect of this review is an intuitive explanation of the negative coupling instability, using field trajectories in the configuration space.

Motivation & Objective

• To investigate the dynamical effects of a negative cross-coupling term in two-scalar-field systems.
• To explore how such a coupling induces instability leading to explosive particle production.
• To assess the implications of this instability for baryogenesis in grand unified theories (GUTs).
• To provide an intuitive understanding of the instability using field trajectories in configuration space.
• To establish a new mechanism for generating the baryon asymmetry of the universe via non-thermal processes.

Proposed method

• Analyzing a two-scalar-field model with a negative cross-coupling term in the potential energy function.
• Using configuration space trajectories to visualize the instability and its onset.
• Applying effective field theory techniques to study inflaton decay dynamics under negative coupling.
• Evaluating the rate of particle production and decay using quantum field theory methods in curved spacetime.
• Assessing the efficiency of baryon number violation in GUT models under the influence of the instability.
• Comparing the instability-driven decay to standard perturbative decay rates to highlight the enhancement.

Experimental results

Research questions

• RQ1 How does a negative cross-coupling term affect the stability and decay dynamics of an inflaton field?
• RQ2 What is the nature of the explosive particle production triggered by such a coupling?
• RQ3 Can this instability lead to efficient baryogenesis in grand unified theories?
• RQ4 How do field trajectories in configuration space illustrate the onset of the instability?
• RQ5 What is the quantitative enhancement of baryon number violation compared to standard thermal or perturbative mechanisms?

Key findings

• A negative cross-coupling induces a tachyonic instability, leading to exponential growth in particle number density.
• The instability results in ultrafast inflaton decay, occurring on time scales much shorter than the Hubble time.
• The explosive particle production enhances non-thermal baryon number violation in GUT models.
• The mechanism provides a viable pathway for generating the observed baryon asymmetry without requiring thermal equilibrium.
• The configuration space trajectory analysis reveals a runaway evolution toward high-energy, high-occupation number states.
• The model shows that even small negative couplings can trigger significant instability, making the effect robust and physically relevant.