The Karlsruhe Tritium Neutrino (KATRIN) experiment is designed to measure the effective electron antineutrino mass with a sensitivity better than $m_\nu < 0.3 \, \mathrm{eV}$ ($90 \, \% \,\mathrm{CL}$) using precision electron spectroscopy of tritium β-decay. This determination occurs in the spectral endpoint ($E_0$) region, up to some $10 \, \mathrm{eV}$ below $E_0 \approx 18.6 \, \mathrm{keV}$.
Light neutral pseudoscalars and vector bosons arise in many theories beyond the Standard Model (BSM). High-statistics β-spectroscopy with KATRIN is a complementary probe for these new physics theories regarding coupling strengths of bosons to neutrinos or electrons.
We consider different scenarios of the emission of additional bosons with characteristic signatures in the shape of the β-spectrum, described in JHEP 01 (2019) 206. We present the sensitivity estimates of the second measurement campaign ($4 \times 10^6$ electrons in the analysis range of $[-40, +130] \, \mathrm{eV}$ around $E_0$) to such light boson couplings.