  The mass scale M_s of superstring theory is an arbitrary parameter that can
be as low as few TeVs if the Universe contains large extra dimensions. We
propose a search for the effects of Regge excitations of fundamental strings at
LHC, in the process p p \to \gamma jet. The underlying parton process is
dominantly the single photon production in gluon fusion, g g \to \gamma g, with
open string states propagating in intermediate channels. If the photon mixes
with the gauge boson of the baryon number, which is a common feature of D-brane
quivers, the amplitude appears already at the string disk level. It is
completely determined by the mixing parameter -- and it is otherwise
model-(compactification-) independent. Even for relatively small mixing, 100
fb^{-1} of LHC data could probe deviations from standard model physics, at a
5\sigma significance, for M_s as large as 3.3 TeV.
