KEKB is the name of the accelerator used in the Belle Experiment to study CP violation. It is called a B-factory for its copious production of B-mesons which provide a golden mode to study and measure the CP violation due to its property of decaying into other lighter mesons. KEKB is basically an asymmetric electron–positron collider, with electrons having the energy of 8 Ge V and positrons having the energy of 3.5 Ge V, giving 10.58 GeV centre-of-mass energy, which is equal to the mass of Upsilon(4S).