Papers by ULISSES DE FREITAS CARNEIRO DA GRACA
Evidence for the decays $B^{0}\rightarrow\bar{D}^{(*)0}\phi$ and updated measurements of the branching fractions of the $B^{0}_{s}\rightarrow\bar{D}^{(*)0}\phi$ decays
HAL (Le Centre pour la Communication Scientifique Directe), Jun 14, 2023
HAL (Le Centre pour la Communication Scientifique Directe), May 12, 2023
A study of prompt Ξ + c production in proton-lead collisions is performed with the LHCb experimen... more A study of prompt Ξ + c production in proton-lead collisions is performed with the LHCb experiment at a centre-of-mass energy per nucleon pair of 8.16 TeV in 2016 in pPb and Pbp collisions with an estimated integrated luminosity of approximately 12.5 and 17.4 nb −1 , respectively. The Ξ + c production cross-section, as well as the Ξ + c to Λ + c production cross-section ratio, are measured as a function of the transverse momentum and rapidity and compared to the latest theory predictions. The forwardbackward asymmetry is also measured as a function of the Ξ + c transverse momentum. The results provide strong constraints on theoretical calculation and are a unique input for hadronisation studies in different collision systems.
HAL (Le Centre pour la Communication Scientifique Directe), Jul 26, 2023
The first observation and study of two new baryonic structures in the final state Ξ 0 b π + π − a... more The first observation and study of two new baryonic structures in the final state Ξ 0 b π + π − and the confirmation of the Ξ b (6100) − state in the Ξ − b π + π − decay mode are reported using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb −1. In addition, the properties of the known Ξ * 0 b , Ξ ′− b and Ξ * − b resonances are measured with improved precision. The new decay mode of the Ξ 0 b baryon to the Ξ + c π − π + π − final state is observed and exploited for the first time in these measurements.
arXiv (Cornell University), Jun 7, 2023
The mass difference between the Ω − b and Ξ − b baryons is measured using protonproton collision ... more The mass difference between the Ω − b and Ξ − b baryons is measured using protonproton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb −1 , and is found to be m(Ω − b) − m(Ξ − b) = 248.54 ± 0.51 (stat) ± 0.38 (syst) MeV/c 2. The mass of the Ω − b baryon is measured to be m(Ω − b) = 6045.9 ± 0.5 (stat) ± 0.6 (syst) MeV/c 2. This is the most precise determination of the Ω − b mass to date. In addition, the production rate of Ω − b baryons relative to that of Ξ − b baryons is measured for the first time in pp collisions, using an LHCb dataset collected at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 6 fb −1. Reconstructing beauty baryons in the kinematic region 2 < η < 6 and p T < 20 GeV/c with their decays to a J/ψ meson and a hyperon, the ratio f Ω − b f Ξ − b × B(Ω − b → J/ψΩ −) B(Ξ − b → J/ψΞ −) = 0.120 ± 0.008 (stat) ± 0.008 (syst), is obtained, where f Ω − b and f Ξ − b are the fragmentation fractions of b quarks into Ω − b and Ξ − b baryons, respectively, and B represents the branching fractions of their respective decays.
Search for $D^{*}(2007)^0\to\mu^+\mu^-$ in $B^-\to\pi^-\mu^+\mu^-$ decays
arXiv (Cornell University), Apr 4, 2023
Measurement of the prompt $D^0$ nuclear modification factor in $p$Pb collisions at $\sqrt{s_\mathrm{NN}} = 8.16$ TeV
HAL (Le Centre pour la Communication Scientifique Directe), Jun 29, 2023
Journal of High Energy Physics
The $$ {\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + decay is ob... more The $$ {\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−1. The $$ {\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + decay is reconstructed partially, where the photon from the $$ {\varXi}_c^{\prime +}\to {\varXi}_c^{+}\gamma $$ Ξ c ′ + → Ξ c + γ decay is not reconstructed and the pK−π+ final state of the $$ {\varXi}_c^{+} $$ Ξ c + baryon is employed. The $$ {\varXi}_{cc}^{++}\to {\varXi}_c^{\prime +}{\pi}^{+} $$ Ξ cc + + → Ξ c ′ + π + branching fraction relative to that of the $$ {\varXi}_{cc}^{++}\to {\varXi}_c^{+}{\pi}^{+} $$ Ξ cc + + → Ξ c + π + decay is measured to be 1.41 ± 0.17 ± 0.10, where the first uncertainty is statistical and the second systematic.
Journal of High Energy Physics
A study of B+→ J/ψηK+ decays, followed by J/ψ → μ+μ− and η → γγ, is performed using a dataset col... more A study of B+→ J/ψηK+ decays, followed by J/ψ → μ+μ− and η → γγ, is performed using a dataset collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. The J/ψη mass spectrum is investigated for contributions from charmonia and charmonium-like states. Evidence is found for the B+→ (ψ2(3823) → J/ψη)K+ and B+→ (ψ(4040) → J/ψη)K+ decays with significance of 3.4 and 4.7 standard deviations, respectively. This constitutes the first evidence for the ψ2(3823) → J/ψη decay.
The first study of the angular distribution of µ + µ − pairs produced in the forward rapidity reg... more The first study of the angular distribution of µ + µ − pairs produced in the forward rapidity region via the Drell-Yan reaction pp → γ * /Z + X → + − + 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.
Measurement of the charm mixing parameter $y_{CP} - y_{CP}^{K\pi}$ using two-body $D^0$ meson decays
The Ξ++ cc → Ξ ′+ c π + decay is observed using proton-proton collisions collected by the LHCb ex... more The Ξ++ cc → Ξ ′+ c π + decay is observed using proton-proton collisions collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb−1. The Ξ++ cc → Ξ ′+ c π + decay is reconstructed partially, where the photon from the Ξ ′+ c → Ξ+ c γ decay is not reconstructed and the pK−π+ final state of the Ξ+ c baryon is employed. The Ξ ++ cc → Ξ ′+ c π + branching fraction relative to that of the Ξ++ cc → Ξ+ c π+ decay is measured to be 1.41±0.17±0.10, where the first uncertainty is statistical and the second systematic.
The first observation of the semileptonic b-baryon decay Λ 0 b → Λ + c τ − ν τ , with a significa... more The first observation of the semileptonic b-baryon decay Λ 0 b → Λ + c τ − ν τ , with a significance of 6.1 σ, is reported using a data sample corresponding to 3 fb −1 of integrated luminosity, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV at the LHC. The τ − lepton is reconstructed in the hadronic decay to three charged pions. The ratio K = B(Λ 0 b → Λ + c τ − ν τ)/B(Λ 0 b → Λ + c π − π + π −) is measured to be 2.46 ± 0.27 ± 0.40, where the first uncertainty is statistical and the second systematic. The branching fraction B(Λ 0 b → Λ + c τ − ν τ) = (1.50 ± 0.16 ± 0.25 ± 0.23)% is obtained, where the third uncertainty is from the external branching fraction of the normalization channel Λ 0 b →Λ + c π − π + π −. The ratio of semileptonic branching fractions R(Λ + c) ≡ B(Λ 0 b → Λ + c τ − ν τ)/B(Λ 0 b → Λ + c µ − ν µ) is derived to be 0.242 ± 0.026 ± 0.040 ± 0.059, where the external branching fraction uncertainty from the channel Λ 0 b →Λ + c µ − ν µ contributes to the last term. This result is in agreement with the standard model prediction.
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Papers by ULISSES DE FREITAS CARNEIRO DA GRACA