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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of D-s(+/-) production asymmetry in pp collisions at root s=7 and 8 TeV. J. High Energy Phys., 08(8), 008–21pp.
Abstract: The inclusive D-s(+/-) production asymmetry is measured in pp collisions collected by the LHCb experiment at centre-of-mass energies of root s = 7 and 8 TeV. Promptly produced D-s(+/-) mesons are used, which decay as D-s(+/-) -> phi pi(+/-), with phi -> K+ K-. The measurement is performed in bins of transverse momentum, pT, and rapidity, y, covering the range 2.5 < pT < 25 : 0 GeV/c and 2.0 < y < 4.5. No kinematic dependence is observed. Evidence of nonzero D-s(+/-) production asymmetry is found with a significance of 3.3 standard deviations.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of CP observables in B-+/- -> D(*)K-+/- and B-+/- -> D(*)pi(+/-) decays. Phys. Lett. B, 777, 16–30.
Abstract: Measurements of CP observables in B-+/- -> D(*)K-+/- and B-+/- -> D(*)pi(+/-) decays are presented, where D(*) indicates a neutral Dor D* meson that is an admixture of D(*)(0) and (D) over bar(*)(0) states. Decays of the D* meson to the D pi(0)and D gamma final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the Bcandidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K-+/-pi(-/+), K+K- and pi(+)pi(-) final states. The analysis uses a sample of charged Bmesons produced in ppcollisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0fb- 1taken at centre- of- mass energies of root s = 7, 8 and 13 TeV, respectively. The study of B-perpendicular to -> D*K-perpendicular to and B-perpendicular to -> D*pi(perpendicular to) decays using a partial reconstruction method is the first of its kind, while the measurement of B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays is an update of previous LHCb measurements. The B-+/- -> DK +/- results are the most precise to date.
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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 CP violation in D-(s)(+) -> h(+) pi(0) and decays D-(s)(+) -> h(+) eta decays. J. High Energy Phys., 06(6), 019–25pp.
Abstract: Searches for CP violation in the two-body decays D-(s)(+) -> h(+)pi(0) and D-(s)(+) -> h(+)eta (where h(+) denotes a pi(+) or K+ meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb(-1) or 6 fb(-1) of integrated luminosity. The pi(0) and eta mesons are reconstructed using the e(+) e(-)gamma final state, which can proceed as three-body decays pi(0) -> e(+) e(-) gamma and eta -> e(+) e(-)gamma, or via the two-body decays pi(0) -> gamma gamma and eta -> gamma gamma followed by a photon conversion. The measurements are made relative to the control modes D-(s)(+) K(S)(0)h(+) to cancel the production and detection asymmetries. The CP asymmetries are measured to be A(CP)(D+ -> pi(+)pi(0)) = (-1.3 +/- 0.9 +/- 0.6)%, A(CP)(D+ -> K+pi(0)) = (- 3.2 +/- 4.7 +/- 2.1)%, A(CP)(D+ -> pi(+)eta) = (-0.2 +/- 0.8 +/- 0.4)%, A(CP)(D+ -> K+eta) = (-6 +/- 10 +/- 4 )%, A(CP)(D-s(+) -> K+pi(0)) = (-0.8 +/- 3.9 +/- 1.2)%, A(CP)(D-s(+) -> pi(+)eta) = ( 0.8 +/- 0.7 +/- 0.5)%, A(CP)(D-s(+) -> K+eta) = ( 0.9 +/- 3.7 +/- 1.1)%, where the first uncertainties are statistical and the second systematic. These results are consistent with no CP violation and mostly constitute the most precise measurements of A(CP) in these decay modes to date.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Evidence for the decay B-s(0) -> (K)over-bar(*0) mu(+)mu(-). J. High Energy Phys., 07(7), 020–24pp.
Abstract: A search for the decay B-s(0) -> (K) over bar (*0) mu(+) mu(-) is presented using data sets corresponding to 1.0, 2.0 and 1.6 fb(-1) of integrated luminosity collected during pp collisions with the LHCb experiment at centre-of-mass energies of 7, 8 and 13TeV, respectively. An excess is found over the background-only hypothesis with a significance of 3.4 standard deviations. The branching fraction of the B-s(0) -> (K) over bar (*0) mu(+) mu(-) decay is determined to be B(B-s(0) -> (K) over bar (*0) mu(+) mu(-)) = [2.9 +/- 1.0 (stat) +/- 0.2 (syst) +/- 0.3 (norm)] x 10(-8), where the first and second uncertainties are statistical and systematic, respectively. The third uncertainty is due to limited knowledge of external parameters used to normalise the branching fraction measurement.
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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). Measurement of differential b(b)over-barand c(c)over-bar-dijet cross-sections in the forward region of pp collisions at root s=13 TeV. J. High Energy Phys., 02(2), 023–37pp.
Abstract: The inclusive b (b) over bar- and c (c) over bar -dijet production cross-sections in the forward region of pp collisions are measured using a data sample collected with the LHCb detector at a centre-of-mass energy of 13TeV in 2016. The data sample corresponds to an integrated luminosity of 1.6 fb(-1). Differential cross-sections are measured as a function of the transverse momentum and of the pseudorapidity of the leading jet, of the rapidity difference between the jets, and of the dijet invariant mass. A fiducial region for the measurement is defined by requiring that the two jets originating from the two b or c quarks are emitted with transverse momentum greater than 20 GeV/c, pseudorapidity in the range 2.2 < eta < 4.2, and with a difference in the azimuthal angle between the two jets greater than 1.5. The integrated b (b) over bar -dijet cross-section is measured to be 53.0 +/- 9.7 nb, and the total c (c) over bar -dijet cross-section is measured to be 73 +/- 16 nb. The ratio between c (c) over bar- and b (b) over bar -dijet cross-sections is also measured and found to be 1.37 +/- 0.27. The results are in agreement with theoretical predictions at next-to-leading order.
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