Implications of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ca</mml:mi><mml:mo>−</mml:mo></mml:mrow><mml:mprescripts/><mml:none/><mml:mn>36</mml:mn></mml:mmultiscripts><mml:mmultiscripts><mml:mi mathvariant="normal">S</mml:mi><mml:mprescripts/><mml:none/><mml:mn>36</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ca</mml:mi><mml:mo>−</mml:mo></mml:mrow><mml:mprescripts/><mml:none/><mml:mn>38</mml:mn></mml:mmultiscripts><mml:mmultiscripts><mml:mi>Ar</mml:mi><mml:mprescripts/><mml:none/><mml:mn>38</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> difference in mirror charge radii on the neutron matter equation of state
B. A. Brown, K. Minamisono, J. Piekarewicz, H. Hergert, D. Garand, A. Klose, Kristian König, Jeremy Lantis, Y. Liu, Bernhard Maaß, A. Miller, W. Nörtershäuser, Skyy Pineda, Robert Powel, D. Rossi, F. Sommer, C. Sumithrarachchi, A. Teigelhöfer, J. Watkins, R. Wirth
Abstract
Charge radii of the unstable 36 Ca and 38 Ca nuclei were recently determined and used to compute differences in charge radii between mirror nuclei R ch for the 36 Ca -36 S and 38 Ca -38 Ar mirror pairs. Given the correlation between R ch and the slope of the symmetry energy L at the nuclear saturation density, we deduce L = 5-70 MeV, which rules out a large fraction of models that predict a "stiff" equation of state. This is the most precise determination of L in this model based on electromagnetic probes of nuclear ground states. The determined range is consistent with earlier analyses from both laboratory experiments and astrophysical observations, including the recent detection of gravitational waves from the merger of two neutron stars.