There have been many recent clinical trials conducted by various organizations proving that the combination of L-Theanine and Caffeine increases the ability to focus without the over stimulating effects of Caffeine alone:
A recent study from The Netherlands confirmed that "The combination of L-Theanine and Caffeine improves the cognitive performance and increases subject alertness." and that the combination "helps to focus attention during a demanding cognitive task." 
The Cognitive Neurophysiology Laboratory in New York conducted testing for 4 days on volunteers from the age of 21 and 40 and found that L-Theanine and Caffeine in combination positively affect human cognition and caused measurable increases in alpha brain waves - the brain waves associated with alertness. 
A UK-based study published in Nutritional Neuroscience found that the combination of L-Theanine and caffeine improved both speed and accuracy of performance when switching between tasks (multi-tasking) and reduced susceptibility to distractions during a memory task. The researchers summarized: "These results replicate previous evidence which suggests that L-Theanine and caffeine in combination are beneficial for improving performance on cognitively demanding tasks." 
A Dutch study gave participants L-Theanine and caffeine in the same 2:1 ratio that Smart Caffeine contains, the asked the participants to complete 2 attention tasks at 10 and 60-minutes after ingestions. The researchers stated that "The results support previous evidence that L-theanine and caffeine in combination can improve attention." 
A review of multiple studies published by the School of Psychology in Australia concluded that "L-theanine may interact with caffeine to enhance performance in terms of attention switching and the ability to ignore distraction; this is likely to be reflective of higher-level cognitive activity."