Abstract: Energy differences between analogue states in the T = 1/2 Mg-23-Na-23 mirror nuclei have been measured along the rotational yrast bands. This allows us to search for effects arising from isospin-symmetrybreaking interactions (ISB) and/or shape changes. Data are interpreted in the shell model framework following the method successfully applied to nuclei in the f(7/2) shell. It is shown that the introduction of a schematic ISB interaction of the same type of that used in the f(7/2) shell is needed to reproduce the data. An alternative novel description, applied here for the first time, relies on the use of an effective interaction deduced from a realistic charge-dependent chiral nucleon-nucleon potential. This analysis provides two important results: (i) The mirror energy differences give direct insight into the nuclear skin; (ii) the skin changes along the rotational bands are strongly correlated with the difference between the neutron and proton occupations of the s(1/2) “halo” orbit.

Abstract: The semileptonic CP asymmetry in B-0-(B) over bar (0) mixing, a(s1)(d), is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb(-1), recorded by the LHCb experiment. Semileptonic B-0 decays are reconstructed in the inclusive final states D-mu(+) and D*(-)mu(+), where the D- meson decays into the K+pi(-)pi(-) final state and the D*(-) meson into the (D) over bar (0)(-> K+pi(-))pi(-) final state. The asymmetry between the numbers of D-(*()-)mu(+) and D-(*()+)mu(-) decays is measured as a function of the decay time of the B-0 mesons. The CP asymmetry is measured to be a(s1)(d) = (-0.02 +/- 0.19 +/- 0.30)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of a(s1)(d) to date and is consistent with the prediction from the standard model.

Abstract: The time-dependent CP asymmetry in B-S(0) -> J/Psi K+K- decays is measured using pp collision data, corresponding to an integrated luminosity of 3.0 fb(-1), collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. In a sample of 96 000 B-S(0) -> J/Psi K+K- decays, the CP-violating phase phi(s) is measured, as well as the decay widths GL and GH of the light and heavy mass eigenstates of the B-s(0)-(B) over bar (0)(s) system. The values obtained are phi(s) = -0.058 +/- 0.049 +/- 0.006 rad, Gamma(s) equivalent to (Gamma(L) + Gamma(H))/2 = 0.6603 +/- 0.0027 +/- 0.0015 ps(-1), and Delta Gamma(s) equivalent to Gamma(L)-Gamma(H) = 0.0805 +/- 0.0091 +/- 0.0032 ps(-1), where the first uncertainty is statistical and the second, systematic. These are the most precise single measurements of those quantities to date. A combined analysis with B-s(0) -> J/Psi pi(+)pi(-) decays gives phi(s) = -0.010 +/- 0.039 rad. All measurements are in agreement with the standard model predictions. For the first time, the phase phi(s) is measured independently for each polarization state of the K+K- system and shows no evidence for polarization dependence.

Abstract: Searches are performed for both promptlike and long-lived dark photons, A ', produced in proton-proton collisions at a center-of-mass energy of 13 TeV. These searches look for A '->mu(+)mu(-) decays using a data sample corresponding to an integrated luminosity of 5.5 fb(-1) collected with the LHCb detector. Neither search finds evidence for a signal, and 90% confidence-level exclusion limits are placed on the gamma-A ' kinetic mixing strength. The promptlike A ' search explores the mass region from near the dimuon threshold up to 70 GeV and places the most stringent constraints to date on dark photons with 214 < m(A ') less than or similar to 740 MeV and 10.6 < m(A ') less than or similar to 30 GeV. The search for long-lived A '->mu(+)mu(-) decays places world-leading constraints on low-mass dark photons with lifetimes O(1)ps.

Abstract: This Letter presents a measurement of the W(+)W(-) production cross section in root s = 7 TeV pp collisions by the ATLAS experiment, using 34 pb(-1) of integrated luminosity produced by the Large Hadron Collider at CERN. Selecting events with two isolated leptons, each either an electron or a muon, 8 candidate events are observed with an expected background of 1.7 +/- 0.6 events. The measured cross section is 41(-16)(+20)(stat) +/- 5(syst) +/- 1(lumi) pb, which is consistent with the standard model prediction of 44 +/- 3 pb calculated at next-to-leading order in QCD.