Double concerto Piano, and Timpani" is commonly known by the title "Double Concerto," where the word "double" refers to the two string bodies rather than to the piano and timpani who are not soloists in the conventional sense. Concerti with more than two solo parts may be known by the terms "triple concerto" (Italian: "Concerto triplo", German: "Tripelkonzert"), "quadruple concerto," etc., but not usually when the instruments of the same type (e.g., Vivaldi's Concerto for Four Violins in B minor, catalogued as RV 580 and transcribed for four harpsichords by Bach as BWV 1065). One common arrangement for a triple concerto is
Double beta decay or double beta decay are predicted to be very long; hence, quadruple beta decay is unlikely to be realized. The eight candidate nuclei for quadruple beta decay include Zr, Xe, and Nd capable of quadruple beta-minus decay, and Xe, Ba, Gd, and Dy capable of quadruple beta-plus decay or electron capture. In theory, quadruple beta decay may be experimentally observable in three of these nuclei, with the most promising candidate being Nd. Double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa,