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The transition disk around the T Tauri star T Cha possesses a large gap,making it a prime target for high-resolution imaging in the context of planetformation. We aim to find signs of disk evolutionary processes by studying thedisk geometry and the dust grain properties at its surface, and to search forcompanion candidates. We analyze a set of VLT/SPHERE data at near-infrared andoptical wavelengths. We performed polarimetric imaging of T Cha with IRDIS (1.6$\mu$m) and ZIMPOL (0.5-0.9 $\mu$m), and obtained intensity images from IRDISdual-band imaging with simultaneous spectro-imaging with IFS (0.9-1.3 $\mu$m).The disk around T Cha is detected in all observing modes and its outer disk isresolved in scattered light with unprecedented angular resolution andsignal-to-noise. The images reveal a highly inclined disk with a noticeableeast-west brightness asymmetry. The significant amount of non-azimuthalpolarization signal in the $U_{\phi}$ images, with a $U_{\phi}$/$Q_{\phi}$peak-to-peak value of 14%, is in accordance with theoretical studies onmultiple scattering. Our optimal axisymmetric radiative transfer modelconsiders two coplanar inner and outer disks, separated by a gap of 0.28"(~30au) in size. We derive a disk inclination of ~69 deg and PA of ~114 deg. Inorder to self-consistently reproduce the intensity and polarimetric images, thedust grains, responsible for the scattered light, need to be dominated by sizesof around ten microns. A point source is detected at an angular distance of3.5" from the central star. It is, however, found not to be co-moving. Weconfirm that the dominant source of emission is forward scattered light fromthe near edge of the outer disk. Our point source analysis rules out thepresence of a companion heavier than ~8.5 $M_{\mathrm{jup}}$ between 0.1" and0.3". The detection limit decreases to ~2 $M_{\mathrm{jup}}$ for 0.3" to 4.0".

New constraints on the disk characteristics and companion candidates around T Cha with VLT/SPHERE