Chill low-fidelity music is recorded with intentional imperfections left in the music, doing this creates a nostalgic texture in the sound, which as a result allows listeners to focus and remember different times in there lives, When we relax the front lobe of our brain focuses, lo-fi music is just one genre of many that can causes this reaction from our bodies.
If chill beats help you study it stands to reason that they also help with concentration, the brain instinctually picks out the imperfections in chill lo-fi music and helps you feel ease making it easier for you to concentrate.