  We study the formation of transient loops in the core of the AR 11890. For
this purpose, we have used the observations recorded by the Atmospheric Imaging
Assembly (AIA) and the Interface Region Imaging Spectrograph (IRIS). For
photospheric field configuration, we have used the line-of-sight (LOS)
magnetograms obtained from the Helioseismic and Magnetic Imager (HMI). The
transient is simultaneously observed in all the UV and EUV channels of AIA and
the three slit-jaw images from IRIS. The co-existence of the transient in all
AIA and IRIS SJI channels suggests the transient's multi-thermal nature. The
transient consists of short loops located at the base of the transient as well
as longe loops. A differential emission measure (DEM) analysis shows that the
transient has a clumpy structure. The highest emission observed at the base is
within the temperature bin of $\log\, T = 6.65 - 6.95$. We observe the longer
loops at a similar temperature, albeit very feeble. Using LOS magnetograms, we
conclude that the magnetic reconnection may have caused the transient. Our
observations further suggest that the physics of the formation of such
transients may be similar to those of typical coronal jets, albeit in different
topological configurations. Such multi-wavelength observations shed light on
the formation of hot plasma in the solar corona and provide further essential
constraints on modeling the thermodynamics of such transients.
