Strained graphene in the presence of external probes

We revise the tight binding approach to strained or curved graphene in the presence of external probes such as Photoemission or Scanning Tunneling Microscopy experiments. We show that extra terms arise in the continuum limit of the tight binding Hamiltonian which can not be accounted for by changes in the hopping parameters due to lattice deformations. These material independent extra couplings are of the same order of magnitude as the standard ones and have a geometric origin. Moreover, we show that no β-independent pseudomagnetic fields exist in strained graphene. The physical relevance of the extra terms to actual experiments involving local probes is discussed.