John Butterworth in The Guardian:
In the mid 1970s, four Soviet physicists, Batlisky, Fadin, Kuraev and Lipatov, made some predictions involving the strong nuclear force which would lead to their initials entering the lore. “BFKL” became a shorthand for a difficult-to-understand but important physical effect which could have big implications for high energy physics.
The strongest of the known fundamental forces of nature is something of an enigma. It holds together the nucleus of every atom – easily overcoming the electromagnetic repulsion between the positively-charged protons in there. The simplest atomic nucleus, that of hydrogen, is a single proton, but even that is held in one piece by the strong force, so tightly that it never falls apart – or at least, it lives billions of times longer than the current age of the observable universe. Truly, strong and stable.
We have a good theory of the strong force, which sits proudly in our Standard Model of particle physics. However, making predictions with this theory is very difficult. This is not simply to say that the sums are hard (they are), but that in many cases we don’t even know what sums we should be doing.
BFKL proposed, or discovered, a new set of sums which could be done using the theory behind the strong force. These sums should have a big effect on a particular type of particle collision, when very small fractions of the particle’s momentum are involved. If the energy of the colliding particles is high enough, this type of collision dominates all the others. So anything that has a big effect on these collisions is an important feature of nature, one that we would like to understand.
More here. [Thanks to Farrukh Azfar.]