title: Ab initio Calculations of Charge Symmetry Breaking in the A=4 Hypernuclei.
abstract: We report on ab initio no-core shell model calculations of the mirror Λ hypernuclei _{Λ}^{4}H and _{Λ}^{4}He, using the Bonn-Jülich leading-order chiral effective field theory hyperon-nucleon potentials plus a charge symmetry breaking Λ-Σ^{0} mixing vertex. In addition to reproducing rather well the 0_{g.s.}^{+} and 1_{exc}^{+} binding energies, these four-body calculations demonstrate for the first time that the observed charge symmetry breaking splitting of mirror levels, reaching hundreds of keV for 0_{g.s.}^{+}, can be reproduced using realistic theoretical interaction models, although with a non-negligible momentum cutoff dependence. Our results are discussed in relation to recent measurements of the _{Λ}^{4}H(0_{g.s.}^{+}) binding energy at the Mainz Microtron [A. Esser et al. (A1 Collaboration), Phys. Rev. Lett. 114, 232501 (2015)] and the _{Λ}^{4}He(1_{exc}^{+}) excitation energy [T.O. Yamamoto et al. (J-PARC E13 Collaboration), Phys. Rev. Lett. 115, 222501 (2015)].
authors.affiliation: Nuclear Physics Institute, 25068 Řež, Czech Republic.|ECT*, Villa Tambosi, 38123 Villazzano (Trento), Italy.|Department of Fundamental Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gazda
authors.affiliation: Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
authors.forename: Avraham
authors.initials: A
authors.lastname: Gal