# Measuring the tilt of primordial gravitational-wave power spectrum from observations

## TL;DR

This paper investigates current constraints and future prospects for measuring the tilt of the primordial gravitational-wave spectrum, which impacts cosmic microwave background polarization and the gravitational wave background.

## Contribution

It provides an analysis of existing constraints and forecasts the potential improvements from future observations of the primordial gravitational-wave spectrum tilt.

## Key findings

- Current constraints on the tilt are limited.
- Future observations could significantly improve tilt measurements.
- Enhanced constraints will inform inflationary models.

## Abstract

Primordial gravitational waves generated during inflation lead to the B-mode polarization in the cosmic microwave background and a stochastic gravitational wave background in the Universe. We will explore the current constraint on the tilt of primordial gravitational-wave spectrum, and forecast how the future observations can improve the current constraint.