Uncertainties and systematics in stellar evolution models of Red Giant   Stars
  In this last decade, our knowledge of evolutionary and structural properties of stars of different mass and chemical composition has significantly improved. This notwithstanding, updated stellar models are still affected by significant and, usually, not negligible uncertainties. These uncertainties are related to our poor knowledge of some physical processes occurring in the real stars such as the efficiency of mixing processes. These drawbacks of stellar models have to be properly taken into account when comparing theory with observations. In this paper we briefly review current uncertainties affecting low-mass stellar models, i.e. those structures with mass in the range between 0.6 Msun and ~1.4 Msun, during the Red Giant Branch stage. 
Santi Cassisi
astro-ph.SR