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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Study of Upsilon(1S) radiative decays to gamma pi(+)pi(-) and gamma K+ K-. Phys. Rev. D, 97(11), 112006–17pp.
Abstract: We study the Upsilon(1S) radiative decays to gamma pi(+)pi(-) and gamma K+K- using data recorded with the BABAR detector operating at the SLAC PEP-11 asymmetric-energy e(+)e(-) collider at center-of-mass energies at the Upsilon(2S) and Upsilon(3S) resonances. The Upsilon(1S) resonance is reconstructed from the decay Upsilon(nS) -> pi(+)pi(-) Upsilon(1S), n =2, 3. Branching fraction measurements and spin-parity analyses of Upsilon(1S) radiative decays are reported for the I = 0 S-wave and f(2) (1270) resonances in the pi(+)pi(-) mass spectrum, the f'(2) (1525) and f(0) (1500) in the K+K mass spectrum, and the f(0)(1710) in both.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Search for the decay mode B-0 -> pp(p)over-bar (p)over-bar. Phys. Rev. D, 98(7), 071102–7pp.
Abstract: A search is presented for the four-body decay B-0 -> pp (p) over bar (p) over bar in a sample of 471 million B (B) over bar pairs collected with the BABAR detector, operated at the SLAC PEP-II asymmetric-energy e(+) e(-) collider. The center-of-mass energy is 10.58 GeV. From a fit to the distribution of the energy-substituted mass m(ES), the branching fraction B(B-0 -> pp (p) over bar (p) over bar) = (1.1 +/- 0.5 +/- 0.2) x 10(-7) is extracted, where the first uncertainty is statistical and the second is systematic. The significance of the signal, including the systematic uncertainty, is 2.9 standard deviations. The upper limit on the branching fraction is determined to be 2.0 x 10(-7) at 90% confidence level.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2018). Study of the process e(+)e(-) -> pi(+)pi(-)eta using initial state radiation. Phys. Rev. D, 97(5), 052007–14pp.
Abstract: We study the process e(+)e(-) -> pi(+)pi(-)eta gamma, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BABAR data sample with an integrated luminosity of 469 fb(-1). Using the pi(+)pi(-)eta invariant mass spectrum, we measure the e(+)e(-) -> pi(+)pi(-)eta cross section in the e(+)e(-) center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson dominance model with four.-like states. We observe 49 +/- 9 events of the J/Psi decay to pi(+)pi(-)eta and measure the product Gamma B-J/Psi -> e+e-(J/Psi ->pi+pi-eta) = 2.34 +/- 0.43(stat) +/- 0.16(syst) eV.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2017). Measurement of the e(+)e(-) -> pi(+)pi(-)pi(0)pi(0) cross section using initial-state radiation at BABAR. Phys. Rev. D, 96(9), 092009–17pp.
Abstract: The process e(+)e(-) -> pi(+)pi(-)2 pi(0)gamma is investigated by means of the initial-state radiation technique, where a photon is emitted from the incoming electron or positron. Using 454.3 fb(-1) of data collected around a centerof- mass energy of root s = 10.58 GeV by the BABAR experiment at SLAC, approximately 150000 signal events are obtained. The corresponding nonradiative cross section is measured with a relative uncertainty of 3.6% in the energy region around 1.5 GeV, surpassing all existing measurements in precision. Using this new result, the channel's contribution to the leading order hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon is calculated as (g(mu)(pi+ pi-2 pi 0) – 2)/2 = (17.9 +/- 0.1(stat) +/- 0.6(syst)) x 10(-10) in the energy range 0.85 GeV < ECM < 1.8 GeV. In the same energy range, the impact on the running of the fine-structure constant at the Z(0)-pole is determined as Delta alpha(pi+ pi-2 pi 0) (M-Z(2)) = (4.44 +/- 0.02(stat) +/- 0.14(syst)) x 10(-4). Furthermore, intermediate resonances are studied and especially the cross section of the process e(+)e(-) -> omega pi(0) -> pi(+)pi(-)2 pi(0) is measured.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2017). Measurement of the D* (2010)(+) -D+ Mass Difference. Phys. Rev. Lett., 119(20), 202003–7pp.
Abstract: We measure the mass difference, Delta m(+), between the D* (2010)(+) and the D+ using the decay chain D* (2010)(+) -> D+ pi(0) with D+ -> K- pi(+)pi(+). The data were recorded with the BABAR detector at center-of-mass energies at and near the (sic)(4S) resonance, and correspond to an integrated luminosity of approximately 468 fb(-1). We measure Delta m(+) = (140601.0 +/- 6.8[stat] +/- 12.9[syst]) keV. We combine this result with a previous BABAR measurement of Delta m(0) = m(D* (2010)(+)) – m(D-0) to obtain Delta m(D) = m(D+) – m(D-0) = (4824.9 +/- 6.8[stat] +/- 12.9[syst]) keV. These results are compatible with and approximately five times more precise than the Particle Data Group averages.
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