2,356 research outputs found

    Consistent Skyrme parametrizations constrained by GW170817

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    The high-density behavior of the stellar matter composed of nucleons and leptons under ÎČ\beta~equilibrium and charge neutrality conditions is studied with the Skyrme parametrizations shown to be consistent (CSkP) with the nuclear matter, pure neutron matter, symmetry energy and its derivatives in a set of 1111 constraints [Dutra {\it et al.}, Phys. Rev. C 85, 035201 (2012)]. The predictions of these parametrizations on the tidal deformabilities related to the GW170817 event are also examined. The CSkP that produce massive neutron stars give a range of 11.86~\mbox{km} \leqslant R_{1.4} \leqslant 12.55~\mbox{km} for the canonical star radius, in agreement with other theoretical predictions. It is shown that the CSkP are compatible with the region of masses and radii obtained from the analysis of recent data from LIGO and Virgo Collaboration (LVC). A correlation between dimensionless tidal deformability and radius of the canonical star is found, namely, Λ1.4≈3.16×10−6R1.47.35\Lambda_{1.4} \approx 3.16\times10^{-6}R_{1.4}^{7.35}, with results for the CSkP compatible with the recent range of Λ1.4=190−120+390\Lambda_{1.4}=190_{-120}^{+390} from LVC. An analysis of the Λ1×Λ2\Lambda_1\times\Lambda_2 graph shows that all the CSkP are compatible with the recent bounds obtained by LVC. Finally, the universal correlation between the moment of inertia and the deformability of a neutron star, named as the \mbox{II-Love} relation, is verified for the CSkP, that are also shown to be consistent with the prediction for the moment of inertia of the \mbox{PSR J0737-3039} primary component pulsar.Comment: 10 pages, 7 figure

    Measurement of Branching Fractions and Rate Asymmetries in the Rare Decays B -> K(*) l+ l-

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    In a sample of 471 million BB events collected with the BABAR detector at the PEP-II e+e- collider we study the rare decays B -> K(*) l+ l-, where l+ l- is either e+e- or mu+mu-. We report results on partial branching fractions and isospin asymmetries in seven bins of di-lepton mass-squared. We further present CP and lepton-flavor asymmetries for di-lepton masses below and above the J/psi resonance. We find no evidence for CP or lepton-flavor violation. The partial branching fractions and isospin asymmetries are consistent with the Standard Model predictions and with results from other experiments.Comment: 16 pages, 14 figures, accepted by Phys. Rev.

    Search for a dark vector gauge boson decaying to π+π−\pi^+ \pi^- using η→π+Ï€âˆ’Îł\eta \rightarrow \pi^+\pi^- \gamma decays

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    We report a search for a dark vector gauge boson Uâ€ČU^\prime that couples to quarks in the decay chain D∗+→D0π+,D0→KS0η,η→Uâ€ČÎłD^{*+} \to D^0 \pi^+, D^0 \to K^0_S \eta, \eta \to U^\prime \gamma, Uâ€Č→π+π−U^\prime \to \pi^+ \pi^-. No signal is found and we set a mass-dependent limit on the baryonic fine structure constant of 10−3−10−210^{-3} - 10^{-2} in the Uâ€ČU^\prime mass range of 290 to 520 MeV/c2c^2. This analysis is based on a data sample of 976 fb−1^{-1} collected by the Belle experiment at the KEKB asymmetric-energy e+e−e^+e^- collider.Comment: 6 pages, 4 figure

    Search for Bs0→γγB_{s}^{0}\rightarrow\gamma\gamma and a measurement of the branching fraction for Bs0â†’Ï•ÎłB_{s}^{0}\rightarrow\phi\gamma

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    We search for the decay Bs0→γγB_{s}^{0}\rightarrow\gamma\gamma and measure the branching fraction for Bs0â†’Ï•ÎłB_{s}^{0}\rightarrow\phi\gamma using 121.4~fb−1\textrm{fb}^{-1} of data collected at the ΄(5S)\Upsilon(\mathrm{5}S) resonance with the Belle detector at the KEKB asymmetric-energy e+e−e^{+}e^{-} collider. The Bs0â†’Ï•ÎłB_{s}^{0}\rightarrow\phi\gamma branching fraction is measured to be (3.6±0.5(stat.)±0.3(syst.)±0.6(fs))×10−5(3.6 \pm 0.5 (\mathrm{stat.}) \pm 0.3 (\mathrm{syst.}) \pm 0.6 (f_{s})) \times 10^{-5}, where fsf_{s} is the fraction of Bs(∗)Bˉs(∗)B_{s}^{(*)}\bar{B}_{s}^{(*)} in bbˉb\bar{b} events. Our result is in good agreement with the theoretical predictions as well as with a recent measurement from LHCb. We observe no statistically significant signal for the decay Bs0→γγB_{s}^{0}\rightarrow\gamma\gamma and set a 90%90\% confidence-level upper limit on its branching fraction at 3.1×10−6 3.1 \times 10^{-6}. This constitutes a significant improvement over the previous result.Comment: 6 pages, 3 figure
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