Precision measurement of the \(E2\) transition strength to the 2\(^+_1\) state of \(^{12}\)C

The form factor of the electromagnetic excitation of \(^{12}\)C to its 2\(^+_1\) state was measured at extremely low momentum transfers in an electron scattering experiment at the S-DALINAC. A combined analysis with the world form factor data results in a reduced transition strength \(B(E2; 2^+_1\rightarrow 0^+_1) =7.63(19)\) e\(^2\)fm\(^4\) with an accuracy improved to 2.5\%. In-Medium-No Core Shell Model results with interactions derived from chiral effective field theory are capable to reproduce the result. A quadrupole moment \(Q(2^+_1) = 5.97(30)\) efm\(^2\) can be extracted from the strict correlation with the \(B((E2)\) strength emerging in the calculations.