"+ h.c." is an abbreviation for the phrase "plus the Hermitian Conjugate".
Notes on verification
Confirmed by physics journal style guides and academic sources as standard notation for 'plus Hermitian conjugate'.
Sources
- + h.c. (en.wikipedia.org)
- https://www.researchgate.net/post/What_is_the_hc_term_that_comes_along_with_hopping_term_t_in_the_single_band_Hubbard_model_of_RVB (researchgate.net)
- https://journals.aps.org/prl/authors/general-notation-terminology (journals.aps.org)
- https://www.physicsforums.com/threads/meaning-of-h-c-in-lagrangians-elsewhere.454071/ (physicsforums.com)
- https://arxiv.org/pdf/1503.07829 (arxiv.org)