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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the reactions e(+)e(-)-> pi(+) pi(-) pi(0)pi(0)pi(0)pi(0) and pi(+) pi(-) pi(0)pi(0)pi(0)eta at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation. Phys. Rev. D, 104(11), 112004–19pp.
Abstract: We study the processes e(+)e(-) -> pi+ pi-pi(0)pi(0)pi(0)pi(0)gamma and pi(+) pi(-) pi(0)pi(0)pi eta gamma in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at the SLAC National Accelerator Laboratory. About 7300 and 870 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb(-1). The invariant mass of the hadronic final state defines the effective e(+)e(-) center-of-mass energy. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the e(+)e(-) -> pi(+)pi(-) pi(0)pi(0)pi(0)pi(0) and the e(+)e(-) -> pi(+)pi(-) pi(0)pi(0)pi(0)eta cross sections are performed. The contributions from omega pi(0)pi(0)pi(0), eta pi(+)pi(-)pi(0), omega eta, and other intermediate states are presented. We observe the J=psi and psi(2S) in most of these final states and measure the corresponding branching fractions, many of them for the first time.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the process e(+) e(-) -> pi(+)pi (-) pi(0) using initial state radiation with BABAR. Phys. Rev. D, 104(11), 112003–31pp.
Abstract: The process e(+)e(-) -> pi(+) pi(-) pi(0)gamma is studied at a center-of-mass energy near the Upsilon(4S) resonance using a data sample of 469 fb(-1) collected with the BABAR detector at the PEP-II collider. We have performed a precise measurement of the e(+)e(-) -> pi(+) pi(-) pi(0) cross section in the center-of-mass energy range from 0.62 to 3.5 GeV. In the energy regions of the omega and phi resonances, the cross section is measured with a systematic uncertainty of 1.3%. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured e(+) e(-) -> pi(+) pi(-) pi(0) cross section from threshold to 2.0 GeV is (45.86 +/- 0.14 +/- 0.58) x 10(-10). From the fit to the measured 3 pi mass spectrum we have determined the resonance parameters Gamma(omega -> e(+)e(-)) B(omega -> pi(+) pi- pi(0)) = (0.5698 +/- 0.0031 +/- 0.0082) keV, Gamma(phi -> e(+)e(-)) B(phi -> pi(+) pi(-)pi(0)) = (0.1841 +/- 0.0021 +/- 0.0080) keV, and B(rho -> 3 pi) = (0.88 +/- 0.23 +/- 0.30) x 10(-4). The significance of the rho -> 3 pi signal is greater than 6 sigma. For the J/psi resonance we have measured the product Gamma(J/psi -> e(+) e(-)) B (J/psi -> 3 pi) = (0.1248 +/- 0.0019 +/- 0.0026) keV.
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Du, M. L., Guo, Z. H., & Oller, J. A. (2021). Insights into the nature of the P-cs(4459). Phys. Rev. D, 104(11), 114034–14pp.
Abstract: We study the nature of the recently observed Pcs(4459) by the LHCb collaboration by employing three methods based on the elastic effective-range expansion and the resulting size of the effective-range, the saturation of the compositeness relation and width of the resonance, and a direct fit to data involving the channels J/psi Lambda, Xi ' c over line D, and Xi c over line D*. We have also considered the addition of a Castillejo-Dalitz-Dyson (CDD) pole but this scenario can be discarded. Our different analyses clearly indicate the molecular nature of the Pcs(4459) with a clear Xi c over line D* dominant component. In relation with heavy-quark-spin symmetry our results also favor the actual existence of two resonances with J=1/2 (the lighter one) and 3/2 (the heavier one) in the energy region of the Pcs(4459). In the scenario of two-resonance for the Pcs(4459), the inclusion of the Xi ' c over line D channel is required for their mass splitting and it allows one to determine the spin structures of the two resonances.
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LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Search for time-dependent CP violation in D-0 -> K+K- and D-0 -> pi(+)pi(-) decays. Phys. Rev. D, 104(7), 072010–23pp.
Abstract: A search for time-dependent violation of the charge-parity symmetry in D-0 -> K+K- and D-0 -> pi(+)pi(-) decays is performed at the LHCb experiment using proton-proton collision data recorded from 2015 to 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb(-1). The D-0 meson is required to originate from a D*(2010)(+) -> D-0 pi(+) decay, such that its flavor at production is identified by the charge of the accompanying pion. The slope of the time-dependent asymmetry of the decay rates of D-0 and (D) over bar (0) mesons into the final states under consideration is measured to be Delta YK+K- = (-2.3 +/- 1.5 +/- 0.3) x 10(-40), Delta Y pi(+)pi(-) = (-4.0 +/- 2.8 +/- 0.4) x 10(-4), where the first uncertainties are statistical and the second are systematic. These results are compatible with the conservation of the charge-parity symmetry at the level of 2 standard deviations and improve the precision by nearly a factor of 2.
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Bruschini, R., & Gonzalez, P. (2021). Coupled-channel meson-meson scattering in the diabatic framework. Phys. Rev. D, 104(7), 074025–16pp.
Abstract: We apply the diabatic framework, a QCD-based formalism for the unified study of quarkoniumlike systems in terms of heavy quark-antiquark and open-flavor meson-meson components, to the description of coupled-channel meson-meson scattering. For this purpose, we first introduce a numerical scheme to find the solutions of the diabatic Schrodinger equation for energies in the continuum, then we derive a general formula for calculating the meson-meson scattering amplitudes from these solutions. We thus obtain a completely nonperturbative procedure for the calculation of open-flavor meson-meson scattering cross sections from the diabatic potential, which is directly connected to lattice QCD calculations. A comprehensive analysis of various elastic cross sections for open-charm and open-bottom meson-meson pairs is performed in a wide range of the center-of-mass energies. The relevant structures are identified, showing a spectrum of quasiconventional and unconventional quarkoniumlike states. In addition to the customary Breit-Wigner peaks, we obtain nontrivial structures such as threshold cusps and minimums. Finally, our results are compared with existing data and with results from our previous bound-state-based analysis, finding full compatibility with both.
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