  We present the characterization of 5 new short-period low-mass eclipsing
binaries from the WFCAM Transit Survey. The analysis was performed by using the
photometric WFCAM J-mag data and additional low- and intermediate-resolution
spectroscopic data to obtain both orbital and physical properties of the
studied sample. The light curves and the measured radial velocity curves were
modeled simultaneously with the JKTEBOP code, with Markov chain Monte Carlo
simulations for the error estimates. The best-model fit have revealed that the
investigated detached binaries are in very close orbits, with orbital
separations of $2.9 \leq a \leq 6.7$ $R_{\odot}$ and short periods of $0.59
\leq P_{\rm orb} \leq 1.72$ d, approximately. We have derived stellar masses
between $0.24$ and $0.72$ $M_{\odot}$ and radii ranging from $0.42$ to $0.67$
$R_{\odot}$. The great majority of the LMEBs in our sample has an estimated
radius far from the predicted values according to evolutionary models. The
components with derived masses of $M < 0.6$ $M_{\odot}$ present a radius
inflation of $\sim$$9\%$ or more. This general behavior follows the trend of
inflation for partially-radiative stars proposed previously. These systems add
to the increasing sample of low-mass stellar radii that are not well-reproduced
by stellar models. They further highlight the need to understand the magnetic
activity and physical state of small stars. Missions like TESS will provide
many such systems to perform high-precision radius measurements to tightly
constrain low-mass stellar evolution models.
