|
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2021). Study of the reactions e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0) and 2(pi(+)pi(-))pi(0)pi(0)eta at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation. Phys. Rev. D, 103(9), 092001–21pp.
Abstract: We study the processes e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0)gamma and 2(pi(+)pi(-))pi(0)pi(0)eta gamma in which an energetic photon is radiated from the initial state. The data were collected with the BABAR detector at SLAC. About 14 000 and 4700 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(-) -> 2(pi(+)pi(-))pi(0)pi(0)pi(0) and the e(+)e(-) -> 2(pi(+)pi(-))pi(0)pi(0)eta cross sections are performed. The contributions from omega pi(+)pi(-)pi(0)pi(0), eta 2(pi(+)pi(-)), 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.
|
|
|
|
Aiola, S., Bandiera, L., Cavoto, G., De Benedetti, F., Fu, J., Guidi, V., et al. (2021). Progress towards the first measurement of charm baryon dipole moments. Phys. Rev. D, 103(7), 072003–15pp.
Abstract: Electromagnetic dipole moments of short-lived particles are sensitive to physics within and beyond the Standard Model of particle physics but have not been accessible experimentally to date. To perform such measurements it has been proposed to exploit the spin precession of channeled particles in bent crystals at the LHC. Progress that enables the first measurement of charm baryon dipole moments is reported. In particular, the design and characterization on beam of silicon and germanium bent crystal prototypes, the optimization of the experimental setup, and advanced analysis techniques are discussed. Sensitivity studies show that first measurements of Lambda(+)(c) and Xi(+)(c) baryon dipole moments can he performed in two years of data taking with an experimental setup positioned upstream of the LHCb detector.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2021). Measurement of the prompt-production cross-section ratio sigma(chi(c2))/sigma(chi(c1)) in pPb collisions at root s(NN)=8.16 TeV. Phys. Rev. C, 103(6), 064905–10pp.
Abstract: This article reports the first measurement of prompt chi(c1) and chi(c2) charmonium production in nuclear collisions at Large Hadron Collider energies. The cross-section ratio sigma(chi(c2))/sigma(chi(c1)) is measured in pPb collisions at root s(NN) = 8.16 TeV, collected with the LHCb experiment. The chi(c1,2) states are reconstructed via their decay to a J/psi meson, subsequently decaying into a pair of oppositely charged muons, and a photon, which is reconstructed in the calorimeter or via its conversion in the detector material. The cross-section ratio is consistent with unity in the two considered rapidity regions. Comparison with a corresponding cross-section ratio previously measured by the LHCb Collaboration in pp collisions suggests that chi(c1) and chi(c2) states are similarly affected by nuclear effects occurring in pPb collisions.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0. Phys. Rev. D, 102(1), 012011–15pp.
Abstract: A measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0 is performed using proton- proton – collision data corresponding to an integrated luminosity of 5 fb(-1) collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(B-s(0) -> (KSKS0)-K-0) = [8.3 +/- 1.6(stat) +/- 0.9(syst) +/- 0.8(norm) +/- 0.3(f(s)/f(d))] x 10(-6), where the first uncertainty is statistical, the second is systematic, and the third and fourth are due to uncertainties on the branching fraction of the normalization mode B-0 -> phi K(S)(0 )and the ratio of hadronization fractions f(s)/f(d). This is the most precise measurement of this branching fraction to date. Furthermore, a measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0 is performed relative to that of the B-s(0) -> (KSKS0)-K-0 channel, and is found to be B(B-s(0) -> (KSKS0)-K-0)/B(B-s(0) -> (KSKS0)-K-0) = [7.5 +/- 3.1(stat) 0.5(syst) +/- 0.3(f(s)/f(d))1 x 10(-2).
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Search for CP violation and observation of P violation in Lambda(0)(b) -> p pi(-) pi(+) pi(-) decays. Phys. Rev. D, 102(5), 051101–12pp.
Abstract: A search for CP violation in the Lambda(0)(b) -> p pi(-) pi(+) pi(-) decay is performed using LHCb data corresponding to an integrated luminosity of 6.6 fb(-1) collected in pp collisions at center-of-mass energies of 7, 8 and 13 TeV. The analysis uses both triple product asymmetries and the unbinned energy test method. The highest significances of CP asymmetry are 2.9 standard deviations from triple product asymmetries and 3.0 standard deviations for the energy test method. Once the global p-value is considered, all results are consistent with no CP violation. Parity violation is observed at a significance of 5.5 standard deviations for the triple product asymmetry method and 5.3 standard deviations for the energy test method. The reported deviations are given in regions of phase space.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). First observation of the decay B-0 -> D-0(D)over-bar(0)K(+)pi(-). Phys. Rev. D, 102(5), 051102–11pp.
Abstract: The first observation of the decay B-0 -> D-0(D) over bar K-0(+)pi(-) is reported using proton-proton collision data corresponding to an integrated luminosity of 4.7 fb(-1) collected by the LHCb experiment in 2011, 2012 and 2016. The measurement is performed in the full kinematically allowed range of the decay outside of the D*(-) region. The ratio of the branching fraction relative to that of the control channel B-0 -> D-0<(DK+)-K-0 pi(-)+ is measured to be R = (14.2 +/- 1.1 +/- 1.0)%, where the first uncertainty is statistical and the second is systematic. The absolute branching fraction of B-0 -> D-0(D) over bar K-0(+)pi(- )decays is thus determined to be B(B-0 -> D-0(D) over bar K-0(+)pi(-)) = (3.50 +/- 0.27 +/- 0.26 +/- 0.30) x 10(-4), where the third uncertainty is due to the branching fraction of the control channel. This decay mode is expected to provide insights to spectroscopy and the charm-loop contributions in rare semileptonic decays.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). First branching fraction measurement of the suppressed decay Xi(0)(c) -> pi(-) Lambda(+)(c). Phys. Rev. D, 102(7), 071101–11pp.
Abstract: The Xi(0)(c) baryon is unstable and usually decays into charmless final states by the c -> sud transition. It can, however, also disintegrate into a pi(-) meson and a Lambda(+)(c) baryon via s quark decay or via cs -> dc weak scattering. The interplay between the latter two processes governs the size of the branching fraction B(Xi(0)(c) -> pi(-) Lambda(+)(c)), first measured here to be (0.55 +/- 0.02 +/- 0.18)%, where the first uncertainty is statistical and second systematic. This result is compatible with the larger of the theoretical predictions that connect models of hyperon decays using partially conserved axial currents and SU(3) symmetry with those involving the heavy-quark expansion and heavy-quark symmetry. In addition, the branching fraction of the normalization channel, B(Xi(+)(c) -> pK(-) pi(+)) = (1.135 +/- 0.002 +/- 0.387)% is measured.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Study of the lineshape of the chi(c1) (3872) state. Phys. Rev. D, 102(9), 092005–20pp.
Abstract: A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of the relative branching fractions of B+ -> h(+) h('+) h('-) decays. Phys. Rev. D, 102(11), 112010–19pp.
Abstract: The relative branching fractions of B+ -> h(+)h('+)h('-) decays, where h((')) is a pion or kaon, are measured. The analysis is performed with a data sample, collected with the LHCb detector, corresponding to an integrated luminosity of 3.0 fb(-1) of pp collisions. The results obtained improve significantly on previous measurements of these quantities, and are important for the interpretation of Dalitz plot analyses of three-body charmless hadronic decays of B+ mesons.
|
|
|
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). First observation of the decay Lambda(0)(b) -> eta(c) (1S)pK(-). Phys. Rev. D, 102(11), 112012–12pp.
Abstract: The decay Lambda(0)(b) -> eta(c) (1S)pK(- )is observed for the first time using a data sample of proton-proton collisions, corresponding to an integrated luminosity of 5.5 fb I, collected with the LHCb experiment at a center-of-mass energy of 13 TeV. The branching fraction of the decay is measured, using the Lambda(0)(b) -> J/psi pK(-) decay as a normalization mode, to be B(Lambda(0)(b) -> eta(c) (1S)pK(-)) = (1.06 +/- 0.16 +/- 0.06(-019)(+0.22)) x 10(-4), where the quoted uncertainties are statistical, systematic and due to external inputs, respectively. A study of the eta(c)(1S)p mass spectrum is performed to search for the P-c(4312)(+) pentaquark state. No evidence is B(Lambda(0)(b) -> P-c(4312)K-+(-))xB(P-c(4312)(+)-> eta(c)(1S)p)/B(Lambda(0)(b) -> eta(c) (1S)pK(-)) < 0.24( ) observed and an upper limit of < 0.24 is obtained at the 95% confidence level.
|
|
