| 1. |
- Aaij, R., et al.
(författare)
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A model-independent measurement of the CKM angle γ in partially reconstructed B±→D∗h± decays with D→K0Sh+h-(h=π,K)
- 2024
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :2
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Tidskriftsartikel (refereegranskat)abstract
- A measurement of CP-violating observables in B± → D∗K± and B± → D∗π±decays is made where the photon or neutral pion from the D∗ → Dγ or D∗ → Dπ0 decayis not reconstructed. The D meson is reconstructed in the self-conjugate decay modes,D → K0Sπ+π− or D → K0SK+K−. The distribution of signal yields in the D decay phasespace is analysed in a model-independent way. The measurement uses a data sample collectedin proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding toa total integrated luminosity of approximately 9 fb−1. The B± → D∗K± and B± → D∗π±CP-violating observables are interpreted in terms of hadronic parameters and the CKM angleγ, resulting in a measurement of γ = (92+21−17)◦. The total uncertainty includes the statisticaland systematic uncertainties, and the uncertainty due to external strong-phase inputs.
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| 2. |
- Aaij, R., et al.
(författare)
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A search for rare B → Dμ+μ− decays
- 2024
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; 2024:2
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Tidskriftsartikel (refereegranskat)abstract
- A search for rare B → Dμ+μ− decays is performed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. No significant signals are observed in the non-resonant μ+μ− modes, and upper limits of B(B0 → D0μ+μ−)< 5.1 × 10−8, B (B+ → D+s μ+μ−) < 3.2 × 10−8, B(B0s → D0μ+μ−)<1.6 × 10−7 and fc/fu · B (B+c → D+s μ+μ−) < 9.6 × 10−8 are set at the 95 % confidencelevel, where fc and fu are the fragmentation fractions of a B meson with a c and u quarkrespectively in proton-proton collisions. Each result is either the first such measurement oran improvement by three orders of magnitude on an existing limit. Separate upper limits arecalculated when the muon pair originates from a J/ψ → μ+μ− decay. The branching fractionof B+c → D+s J/ψ multiplied by the fragmentation-fraction ratio is measured to befc/fu · B(B+c → D+s J/ψ)= (1.63 ± 0.15 ± 0.13) × 10−5,where the first uncertainty is statistical and the second systematic.
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| 3. |
- Aaij, R., et al.
(författare)
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A study of CP violation in the decays B± → [K + K −π+π− ]D h± (h = K, π) and B± → [π+π−π+π− ]D h±
- 2023
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052.
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Tidskriftsartikel (refereegranskat)abstract
- The first study of CP violation in the decay mode B-+/- -> [K+K-pi(+)pi(-)](D)h(+/-), with h = K, pi, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9fb(-1). The analysis is performed in bins of phase space, which are optimised for sensitivity to local CP asymmetries. CP-violating observables that are sensitive to the angle gamma of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for B-+/- -> [K+K-pi(+)pi(-)](D)h(+/-) and B-+/- -> [pi(+)pi(-)pi(+)pi(-)](D)h(+/-) decays.
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| 4. |
- Aaij, R., et al.
(författare)
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Amplitude analysis of B0? : D0Ds+p - and B plus ? D -Ds plus p plus decays
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- Resonant contributions in B0 & RARR; over bar D0D+s & pi;- and B+ & RARR; D-D+s & pi;+ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the Ds & pi; decay channel.
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| 5. |
- Aaij, R., et al.
(författare)
-
Amplitude Analysis of the B0 →k∗0μ+μ- Decay : Physical Review Letters
- 2024
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Ingår i: Physical Review Letters. - 1079-7114. ; 132:13
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Tidskriftsartikel (refereegranskat)abstract
- An amplitude analysis of the B0→K∗0μ+μ- decay is presented using a dataset corresponding to an integrated luminosity of 4.7 fb-1 of pp collision data collected with the LHCb experiment. For the first time, the coefficients associated to short-distance physics effects, sensitive to processes beyond the standard model, are extracted directly from the data through a q2-unbinned amplitude analysis, where q2 is the μ+μ- invariant mass squared. Long-distance contributions, which originate from nonfactorizable QCD processes, are systematically investigated, and the most accurate assessment to date of their impact on the physical observables is obtained. The pattern of measured corrections to the short-distance couplings is found to be consistent with previous analyses of b- to s-quark transitions, with the largest discrepancy from the standard model predictions found to be at the level of 1.8 standard deviations. The global significance of the observed differences in the decay is 1.4 standard deviations. © 2024 CERN.
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| 6. |
- Aaij, R., et al.
(författare)
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Amplitude analysis of the ?c+- pK-p+ decay and ?c+ baryon polarization measurement in semileptonic beauty hadron decays
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- An amplitude analysis of A+c - pK- & pi;+ decays together with a measurement of the A+c polarization vector in semiOleptonic beauty hadron decays is presented. A sample of 400 000 candidates is selected from proton-proton collisions recorded by the LHCb detector at a center-of-mass energy of 13 TeV. An amplitude model is developed and the resonance fractions as well as two- and three-body decay parameters are reported. The mass and width of the Ao2000 thorn state are also determined. A significant A+c polarization is found. A large sensitivity of the A+c - pK-& pi;+ decay to the polarization is seen, making the amplitude model suitable for A+c polarization measurements in other systems.
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| 7. |
- Aaij, R., et al.
(författare)
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Amplitude analysis of the D+-> pi(-)pi(+)pi(+) decay and measurement of the pi(-)pi(+) S-wave amplitude
- 2023
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479.
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Tidskriftsartikel (refereegranskat)abstract
- An amplitude analysis of the D+-> (-)pi(+)pi(+) decay is performed with a sample corresponding to 1.5 fb(-1) of integrated luminosity of pp collisions at a centre-of-mass energy root s = 8 TeV collected by the LHCb detector in 2012. The sample contains approximately six hundred thousand candidates with a signal purity of 95%. The resonant structure is studied through a fit to the Dalitz plot where the pi(-)pi(+) S-wave amplitude is extracted as a function of pi(-)pi(+) mass, and spin-1 and spin-2 resonances are included coherently through an isobar model. The S-wave component is found to be dominant, followed by the rho(770)(0)pi(+) and f(2)(1270)pi(+) components. A small contribution from the omega(782) -> pi(-)pi(+) decay is seen for the first time in the D+-> pi(-)pi(+)pi(+) decay.
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| 8. |
- Aaij, R., et al.
(författare)
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Amplitude analysis of the D+s → π-π+π+ decay
- 2023
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- A Dalitz plot analysis of the D-s(+) -> pi(-)pi(+)pi(+) decay is presented. The analysis is based on proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of 8TeV and corresponding to an integrated luminosity of 1.5 fb(-1). The resonant structure of the decay is obtained using a quasi-model-independent partial-wave analysis, in which the pi(+)pi(-) S-wave amplitude is parameterised as a generic complex function determined by a fit to the data. The S-wave component is found to be dominant, followed by the contribution from spin-2 resonances and a small contribution from spin-1 resonances. The latter includes the first observation of the D-s(+) -> omega(782)pi(+) channel in the D-s(+) -> pi(-)pi(+)pi(+) decay. The resonant structures of the D-s(+) -> pi(-)pi(+)pi(+) and D+ -> pi(-)pi(+)pi(+) decays are compared, providing information about the mechanisms for the hadron formation in these decays.
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| 9. |
- Aaij, R., et al.
(författare)
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Analysis of Neutral B-Meson Decays into Two Muons
- 2022
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 128:4
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Tidskriftsartikel (refereegranskat)abstract
- The branching fraction B(B-s(0)->mu(+)mu(-)) = (3.09(-0.43-0.11)(+0.46+0.15)) x 10(-9) and the effective lifetime to tau(B-s(0) -> mu(+)mu(-)) = 2.07 +/- 0.29 +/- 0.03 ps are measured, where the first uncertainty is statistical and the second systematic. No significant signal for B-0 ->mu(+)mu(-)gamma) and B-s(0)->mu(+)mu(-)gamma decays is found and upper limits B(B(B-0 ->mu(+)mu(-)) < 2.6 x 10(-10) and B(B-s(0) -> mu(+)mu(-)gamma) < 2.0 x 10(-9) at the 95% C.L. are determined, where the latter is limited to the range m(mu mu) > 4.9 GeV/c(2). The results are in agreement with the standard model expectations.Branching fraction and effective lifetime measurements of the rare decay B-s(0) -> mu(+)mu(-) and searches for the decays B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-)gamma are reported using proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a luminosity of 9 fb(-1).
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| 10. |
- Aaij, R., et al.
(författare)
-
Angular analysis of B0->D-Ds+ with Ds+-> Ds+gamma decays
- 2021
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :6
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Tidskriftsartikel (refereegranskat)abstract
- The first full angular analysis of the B0 -> D-Ds+ decay is performed using 6 fb(-1) of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The Ds+-> Ds+gamma and D*- -> D0- vector meson decays are used with the subsequent Ds+ -> K+K-pi (+) and D0 -> K+pi (-) decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be f(L) = 0.578 +/- 0.010 +/- 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [B(B0 -> D-Ds+) x B(Ds+-> Ds+gamma)]/B(B-0 -> D(*-)Ds+) is measured to be 2.045 +/- 0.022 +/- 0.071 with world-best precision. In addition, the first observation of the Cabibbo-suppressed B-s -> D(*-)Ds+ decay is made with a significance of seven standard deviations. The branching fraction ratio B(B-s -> D(*-)Ds+)/B(B-0 -> D(*-)Ds+) is measured to be 0.049 +/- 0.006 +/- 0.003 +/- 0.002, where the third uncertainty is due to limited knowledge of the ratio of fragmentation fractions.
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