How much can we learn about the physics of inflation?

Area of Science:

• Cosmology and astrophysics, focusing on the early universe and cosmic microwave background radiation.
• Theoretical physics, specifically inflationary cosmology and fundamental field theory.

Background:

• The BICEP2 experiment detected B-mode polarization in the cosmic microwave background (CMB), suggesting an inflationary energy scale of 2 × 10^16 GeV.
• Inflationary cosmology proposes a period of rapid expansion in the very early universe, leaving imprints on the CMB.
• The detection of primordial gravitational waves during inflation is a key prediction to be verified.

Purpose of the Study:

• To investigate how future cosmic microwave background (CMB) polarization experiments can further constrain inflationary models.
• To determine the capabilities of different experimental resolutions in probing inflationary physics.
• To test consistency relations predicted by inflationary models.

Main Methods:

• Analysis of the potential scientific return from proposed CMB polarization experiments with varying angular resolutions.
• Simulations to assess the precision achievable in measuring cosmological parameters, such as the tensor-to-scalar ratio.
• Theoretical framework to connect observational data (e.g., tensor tilt) to inflationary model predictions.

Main Results:

• Low-resolution experiments can constrain the tensor-to-scalar ratio to the percent level, enabling model discrimination.
• High-resolution experiments are crucial for measuring the tensor spectrum tilt.
• Confirmation of the BICEP2 signal would necessitate further detailed measurements to test inflationary consistency relations.

Conclusions:

• Future CMB polarization experiments hold significant potential for advancing our understanding of cosmic inflation.
• A combination of low and high-resolution experiments is optimal for comprehensively probing inflationary physics.
• Measuring the tensor tilt will provide critical tests for the consistency of inflationary models with observational data.