IR Divergence in Inflationary Tensor Perturbations from Fermion Loops

Abstract

We estimate fermion loop corrections to the two-point correlation function of primordial tensor perturbations in a slow-roll inflationary background. We particularly compute an explicit term of one-loop correction from a massless fermion, and then extend to the complete Interaction Hamiltonian. After that, we study one-loop corrections contributed by a massive fermion to primordial tensor fluctuations. The loop correction arisen from a massless fermion field contains logarithms and thus may constrain the validity of perturbation theory in inflationary cosmology, but the situation could be relaxed once the fermion's mass is taken into account. Another one-loop diagram for a massive fermion which involves one vertex is constrained by a UV cutoff as expected by quantum field theory. Our result shows that loop corrections of a fermion field have the same sign as those of a scalar field, and thus implies that the inclusion of fermion loop corrections may not help to alleviate the issue of IR divergence in inflationary cosmology.

12 pages

References in corpus (17)

• Quantum Contributions to Cosmological Correlations II: Can These Corrections Become Large?
• On the one loop corrections to inflation and the CMB anisotropies
• Generation of fluctuations during inflation: comparison of stochastic and field-theoretic approaches
• Stochastic growth of quantum fluctuations during slow-roll inflation
• On the divergences of inflationary superhorizon perturbations
• On the One Loop Corrections to Inflation II: The Consistency Relation
• On Resumming Inflationary Perturbations beyond One-loop
• Dark Energy Model with Spinor Matter and Its Quintom Scenario
• Cosmology With Many Light Scalar Fields: Stochastic Inflation and Loop Corrections
• IR divergence does not affect the gauge-invariant curvature perturbation
• Quantum Gravity Corrections to the One Loop Scalar Self-Mass during Inflation
• The Zeta-Zeta Correlator Is Time Dependent
• On the Physical Significance of Infra-red Corrections to Inflationary Observables
• Inflationary Infrared Divergences: Geometry of the Reheating Surface vs. delta N Formalism
• Quantum Cosmological Correlations in an Inflating Universe: Can fermion and gauge fields loops give a scale free spectrum?
• Cosmological UV/IR Divergences and de-Sitter Spacetime
• Probing Noncommutativity with Inflationary Gravitational Waves