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

Abstract

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 $B(E2;2_1^{+}\to 0_1^{+})=7.63(19)$ 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.

6 pages, 6 figures, submitted to Phys. Rev. C