  We report experimental and theoretical evidence of strong electron-plasmon
interaction in n-doped single-layer MoS2. Angle-resolved photoemission
spectroscopy (ARPES) measurements reveal the emergence of distinctive
signatures of polaronic coupling in the electron spectral function.
Calculations based on many-body perturbation theory illustrate that electronic
coupling to two-dimensional (2D) carrier plasmons provides an exhaustive
explanation of the experimental spectral features and their energies. These
results constitute compelling evidence of the formation of plasmon-induced
polaronic quasiparticles, suggesting that highly-doped transition-metal
dichalcogenides may provide a new platform to explore strong-coupling phenomena
between electrons and plasmons in 2D.
