According to the info found at Geekbench and GFXBench, the new Sony smartphone (model number E2303) runs Android 5.0 Lollipop, and is powered by an octa-core, 64-bit Snapdragon 615 processor, while its 5.2-inch display has a 720 x 1280 pixel resolution. Other features seemingly include a 12 MP rear camera, a 5 MP front-facing camera, 2 GB of RAM, and only 4 GB of internal memory.
All in all, the Sony E2303 appears to be a mid-range handset - perhaps a successor to last year's Xperia C3 (pictured above), which also has a 5 MP front-facing camera and a 720p display.
Since Sony won't announce the Xperia Z4 at MWC 2015 next month, maybe it will showcase this mysterious E2303 smartphone there. We'll just have to wait and see what happens.
sources: GFXBench, Geekbench