Research

I study

physics beyond the Standard Model, dark matter, astroparticle physics, cosmology, particle colliders.

Here are summaries of what I have discovered and co-discovered. Here's a podcast on some of it.

Much of my time is spent trying to fathom the nature of dark matter, the ubiquitous, invisible, mysterious stuff that lurks in 85% of the mass of the universe, and is responsible for giving the cosmos its current look on large scales. I have proposed new experiments to unveil dark matter in the sky and in laboratory detectors, and taken part in a search at an underground experiment, DEAP-3600 at SNOLAB. I also study detection of neutrinos from supernovae; I am part of the SuperNova Early Warning System (SNEWS) collaboration.

Additionally, I research scenarios that address long-standing puzzles regarding the Fermi scale (10-16 cm) in the setting of particle colliders.

See who peoples our research group.

Selected publications

[Full list in Google Scholar, InspireHEP, arXiv.]

*featured as Editors' Suggestion.

Exploring reheated sub-40000 Kelvin neutron stars with JWST, ELT, and TMT,

N. Raj, P. Shivanna, G. N. Rachh,

Phys. Rev. D 109 (2024), 123040*

Dark matter in compact stars,
J. Bramante,  N. Raj,
Phys.Rept. 1052 (2024) 1-48
Breaking up the proton: an affair with dark forces,
G. Kribs, D. McKeen, N. Raj,
Phys. Rev. Lett. 126 (2021), 011801

Hydrogen portal to exotic radioactivity,
D. McKeen, M. Pospelov, N. Raj,
Phys. Rev. Lett. 125 (2020) 23, 231803*

Neutrinos from Type Ia and failed core-collapse supernovae at dark matter detectors,
N. Raj,
Phys. Rev. Lett. 124 (2020) 14, 141802

Non-resonant exotica in LHC dilepton angular spectra,
N. Raj,
Phys. Rev. D 95 (2017) 1, 015011

based on which the CMS collaboration at LHC conducted a search in 2025: 

Search for t-channel scalar and vector leptoquark exchange in the high-mass dimuon and dielectron spectra in proton-proton collisions at 13 TeV

An infrared window on dark kinetic heating of neutron stars,
M. Baryakhtar, J. Bramante, S. Li, T. Linden, N. Raj,
Phys. Rev. Lett. 119 (2017) 13, 131801

First laboratory constraints on Planck-scale mass dark matter,
DEAP-3600 collaboration & N. Raj,
Phys. Rev. Lett. 128 (2022), 011801