Precision Computation of f_K/f_π from Staggered 2+1+1 Flavor Simulations

Project “Precision computation of f_K/f_π from staggered 2+1+1 flavor simulations“ aims at a precision test of the first-row unitarity relation of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. To this end, a team of scientists of the University of Wuppertal and Forschungszentrum Jülich under leadership of Dr. Stephan Duerr computes the ratio f_K/f_π of the leptonic decay constants of the kaon and the pion. The computation is from first principles, by solving the relevant equations of motion in the underlying fundamental theory, known as ``quantum chromodynamics'' (QCD). Once the result is in hand, the scientists use it to obtain a precise value of the CKM element |V_us| based on |V_ud| which is known very accurately. By combining this with the known element |V_ub| the scientists can test whether the relation

|V_ud|² + |V_us|² + |V_ub|² = 1

holds within errors. Any deviation would signal the presence of new physics in the aforementioned leptonic decays.

Source: Copyright: University of Wuppertal

Dr. Stephan Duerr
Wuppertal University / IAS/JSC at Forschungszentrum Jülich
D-42119 Wuppertal / D-52425 Jülich
http://www.durr.itp.unibe.ch