The abbreviation '+ h.c.' stands for 'plus the Hermitian Conjugate'.
Notes on verification
Multiple independent physics sources (ScienceDirect, PRL style guide, Quantum Diaries, ResearchGate) confirm the standard notation meaning.
Sources
- + h.c. (en.wikipedia.org)
- https://www.sciencedirect.com/topics/mathematics/hermitian-conjugate (sciencedirect.com)
- 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://www.quantumdiaries.org/2011/06/26/cern-mug-summarizes-standard-model-but-is-off-by-a-factor-of-2/ (quantumdiaries.org)
- https://journals.aps.org/prl/authors/general-notation-terminology (journals.aps.org)