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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2023). Measurement of CP asymmetries in D-(s)(+) -> eta pi(+) and D-(s)(+) -> eta 'pi(+) decays. J. High Energy Phys., 04(4), 081–23pp.
Abstract: Searches for CP violation in the decays D-(s)(+) -> eta pi(+) and D-(s)(+) -> eta'pi(+) are performed using pp collision data corresponding to 6 fb(-1) of integrated luminosity collected by the LHCb experiment. The calibration channels D-(s)(+) -> phi pi(+) are used to remove production and detection asymmetries. The resulting CP-violating asymmetries are A(CP) (D+ -> eta pi(+)) = (0.34 +/- 0.66 +/- 0.16 +/- 0.05)%, A(CP) (D-s(+) -> eta pi(+)) = (0.32 +/- 0.51 +/- 0.12)%, A(CP) (D+ -> eta'pi(+)) = (0.49 +/- 0.18 +/- 0.06 +/- 0.05)%, A(CP) (D-s(+) -> eta'pi(+)) = (0.01 +/- 0.12 +/- 0.08)%, where the first uncertainty is statistical, the second is systematic and the third, relevant for the D+ channels, is due to the uncertainty on A(CP) (D+ -> phi pi(+)). These measurements, currently the most precise for three of the four channels considered, are consistent with the absence of CP violation. A combination of these results with previous LHCb measurements is presented.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2023). Observation of sizeable w contribution to chi c1(3872) -> pi+ pi- J/Psi decays. Phys. Rev. D, 108(1), L011103–12pp.
Abstract: Resonant structures in the dipion mass spectrum from & chi;c1(3872) & RARR; & pi;+& pi;-J=& psi; decays, produced via B+ & RARR; K+& chi;c1(3872) decays, are analyzed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1. A sizeable contribution from the isospin conserving & chi;c1(3872) & RARR; & omega;J=& psi; decay is established for the first time, (21.4 & PLUSMN; 2.3 & PLUSMN; 2.0)%, with a significance of more than 7.1 & sigma;. The amplitude of isospin violating decay, & chi;c1(3872) & RARR; & rho;0J=& psi;, relative to isospin conserving decay, & chi;c1(3872) & RARR; & omega;J=& psi;, is properly determined, and it is a factor of 6 larger than expected for a pure charmonium state.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2023). Direct CP violation in charmless three-body decays of B± mesons. Phys. Rev. D, 108(1), 012008–17pp.
Abstract: Measurements of CP asymmetries in charmless three-body decays of B-+/- mesons are reported using proton-proton collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.9 fb(-1). The previously observed CP asymmetry in B-+/- -> pi(K+K-)-K-+/- decays is confirmed, and CP asymmetries are observed with a significance of more than five standard deviations in the B-+/- -> pi(+/-)pi(+)pi and B-+/- -> (KK+K-)-K-+/- decays, while the CP asymmetry of B-+/- -> K-+/-pi(+)pi(-) decays is confirmed to be compatible with zero. The distributions of these asymmetries are also studied as a function of the three-body phase space and suggest contributions from rescattering and resonance interference processes. An indication of the presence of the decays B+ -> pi(+) chi(c0) (1P) in both B+ ->pi(+)pi(+)pi and B+ ->pi+K+K- decays is observed, as is CP violation involving these amplitudes.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., Remon Alepuz, C., et al. (2022). First Measurement of the Z -> mu(+) mu(-) Angular Coefficients in the Forward Region of pp Collisions at root s=13 TeV. Phys. Rev. Lett., 129(9), 091801–11pp.
Abstract: The first study of the angular distribution of mu(+) mu(-) pairs produced in the forward rapidity region via the Drell-Yan reaction pp -> gamma*/Z + X -> l(+) l(-) + X is presented, using data collected with the LHCb detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1 fb(-1). The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the Z-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., Remon Alepuz, C., et al. (2023). Measurement of the Lambda(+)(c) to D-0 production ratio in periphera PbPb collisions at root s(NN)=5.02 TeV. J. High Energy Phys., 06(6), 132–26pp.
Abstract: We report on a measurement of the Lambda(+)(c) to D-0 production ratio in peripheral PbPb collisions at root sNN = 5.02TeV with the LHCb detector in the forward rapidity region 2 < y < 4.5. The Lambda(+)(c) (D-0) hadrons are reconstructed via the decay channel Lambda(+)(c) -> pK(-)pi(+) (D-0 -> K- pi(+)) for 2 < pT < 8 GeV/ c and in the centrality range of about 65-90%. The results show no significant dependence on pT, y or the mean number of participating nucleons. They are also consistent with similar measurements obtained by the LHCb collaboration in pPb and Pbp collisions at root sNN = 5.02TeV. The data agree well with predictions from PYTHIA in pp collisions at root s = 5TeV but are in tension with predictions of the Statistical Hadronization model.
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