Supersymmetric B-L inflation near the conformal coupling
  We investigate a novel scenario of cosmological inflation in a gauged $B-L$
extended minimal supersymmetric Standard Model with R-symmetry. We use a
noncanonical K\"{a}hler potential and a superpotential, both preserving the
R-symmetry to construct a model of slow-roll inflation. The model is controlled
by two real parameters: the nonminimal coupling $\xi$ that originates from the
K\"{a}hler potential, and the breaking scale $v$ of the $U(1)_{B-L}$ symmetry.
We compute the spectrum of the cosmological microwave background radiation and
show that the prediction of the model fits well the recent Planck satellite
observation for a wide range of the parameter space. We also find that the
typical reheating temperature of the model is low enough to avoid the gravitino
problem but nevertheless allows sufficient production of the baryon asymmetry
if we take into account the effect of resonance enhancement. The model is free
from cosmic strings that impose stringent constraints on generic $U(1)_{B-L}$
based scenarios, as in our scenario the $U(1)_{B-L}$ symmetry is broken from
the onset.
