The Invisibles (2026)

Astroparticle Physics is the interface of particle physics, astrophysics, and cosmology. This is an exciting area of contemporary research which is going through its golden age - there is a lot of data, several important problems that have been identified, a few have been solved, and several more are expected to be solved within the next few decades.

This course will focus on the "Invisibles" -- neutrinos, dark matter, and gravitational waves -- 3 "dark" messengers that are relatively less well explored (compared to the old trustworthy friend -- photons).

The underlying theme of the course will be that 

• "Particle physics is the engine that drives the Universe" and "the Universe is a fantastic particle physics lab."

• Various interesting aspects of astroparticle physics are best seen as effective theories / controlled approximations of a unified picture that simplify under special circumstances (separation of scales).

• Owing to the special circumstances, one does not always need the full machinery of GR and QFT, but a heuristic approach using (glorified) dimensional analysis, etc. allow us to make a lot of progress.

The expected outcome of the course is that you will be able to

• Perform order-of-magnitude and scaling analyses of key astroparticle processes.

• Derive and interpret fundamental results in neutrinos, DM, and GW research.

• Connect particle microphysics to cosmology and astronomical observables.

• Understand and analyze experimental strategies across a variety of detection methods.

• Synthesize multi-messenger observations to constrain models.