Engineering topics

Abdelmotteleb, A. W.

Publications and source records attributed to Abdelmotteleb, A. W..

At least 37 records · Page 2

DOE OSTI2023

Measurement of the ${\Lambda}_c^{+}$ to D 0 production ratio in peripheral PbPb collisions at $\sqrt{s_{\textrm{NN}}}$ = 5.02 TeV

We report on a measurement of the ${\Lambda}_c^{+}$ to D 0 production ratio in peripheral PbPb collisions at $\sqrt{s_{\textrm{NN}}}$ = 5.02 TeV 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 – π + (D 0 → K – π + ) for 2 < p T < 8 GeV/c and in the centrality range of about 65–90%. The results show no significant dependence on p T , 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 $\sqrt{s_{\textrm{NN}}}$ = 5.02 TeV. The data agree well with predictions from PYTHIA in pp collisions at $\sqrt{s}$ = 5 TeV but are in tension with predictions of the Statistical Hadronization model.

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DOE OSTI2023

Search for the lepton-flavour violating decays B0 → K *0 μ ± e ∓ and ${B}_s^0$ → Φμ ± e ∓

A search for the lepton-flavour violating decays B 0 → K *0 μ ± e ∓ and $ {B}_s^0 $ → Φμ ± e ∓ is presented, using proton-proton collision data collected by the LHCb detector at the LHC, corresponding to an integrated luminosity of 9 fb - 1 . No significant signals are observed and upper limits of $$ {\displaystyle \begin{array}{c}\mathcal{B}\left({B}^0\to {K}^{\ast 0}{\mu}^{+}{e}^{-}\right)<5.7\times {10}^{-9}\left(6.9\times {10}^{-9}\right),\\ {}\mathcal{B}\left({B}^0\to {K}^{\ast 0}{\mu}^{-}{e}^{+}\right)<6.8\times {10}^{-9}\left(7.9\times {10}^{-9}\right),\\ {}\mathcal{B}\left({B}^0\to {K}^{\ast 0}{\mu}^{\pm }{e}^{\mp}\right)<10.1\times {10}^{-9}\left(11.7\times {10}^{-9}\right),\\ {}\mathcal{B}\left({B}_s^0\to \phi {\mu}^{\pm }{e}^{\mp}\right)<16.0\times {10}^{-9}\left(19.8\times {10}^{-9}\right)\end{array}} $$ are set at 90% (95%) confidence level. These results constitute the world’s most stringent limits to date, with the limit on the decay $ {B}_s^0 $ → Φμ ± e ∓ the first being set. In addition, limits are reported for scalar and left-handed lepton-flavour violating New Physics scenarios.

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DOE OSTI2023

Amplitude analysis of the $D^+$ → $π^-π^+π^+$ decay and measurement of the $π^-π^+$ S-wave amplitude

An amplitude analysis of the $D^+$ → $π^-π^+π^+$ decay is performed with a sample corresponding to 1.5 fb -1 of integrated luminosity of $pp$ collisions at a centre-of-mass energy $\sqrt{s}$ = 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 $π^-π^+$ S-wave amplitude is extracted as a function of $π^-π^+$ 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 $ρ(770)^0π^+$ and $f_2(1270)π^+$ components. A small contribution from the $ω$(782) → $π^-π^+$ decay is seen for the first time in the $D^+$ → $π^-π^+π^+$ decay.

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DOE OSTI2023

Measurement of the Z boson production cross-section in proton-lead collisions at $\sqrt{s_{\textrm{NN}}}$ = 8.16 TeV

This article presents the first measurement of the differential Z-boson production cross-section in the forward region using proton-lead collisions with the LHCb detector. The dataset was collected at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{NN}}$ = 8.16 TeV in 2016, corresponding to an integrated luminosity of 30.8 nb –1 . The forward-backward ratio and the nuclear modification factors are measured together with the differential cross-section as functions of the Z boson rapidity in the centre-of-mass frame, the transverse momentum of the Z boson and a geometric variable $\phi$*. The results are in good agreement with the predictions from nuclear parton distribution functions, providing strong constraining power at small Bjorken-x.

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DOE OSTI2023

Measurement of CP asymmetries in ${D}_{(s)}^{+}\to \eta {\pi}^{+}$ and ${D}_{(s)}^{+}\to {\eta}^{\prime }{\pi}^{+}$ decays

Searches for CP violation in the decays ${D}_{(s)}^{+}\to \eta {\pi}^{+}$ and ${D}_{(s)}^{+}\to {\eta}^{\prime }{\pi}^{+}$ are performed using pp collision data corresponding to 6 fb –1 of integrated luminosity collected by the LHCb experiment. The calibration channels ${D}_{(s)}^{+}\to \phi {\pi}^{+}$ are used to remove production and detection asymmetries. The resulting CP-violating asymmetries are $\mathcal{A}^{CP} = (D^+ \to ηπ^+) = (0.34 ± 0.66 ± 0.16 ± 0.05)$ %, $\mathcal{A}^{CP} = (D^+_s \to ηπ^+) = (0.32 ± 0.51 ± 0.12)$ %, $\mathcal{A}^{CP} = (D^+ \to η'π^+) = (0.49 ± 0.18 ± 0.06 ± 0.05)$ %, $\mathcal{A}^{CP} = (D^+_s \to η'π^+) = (0.01 ± 0.12 ± 0.08)$ %, where the first uncertainty is statistical, the second is systematic and the third, relevant for the D + channels, is due to the uncertainty on ${\mathcal{A}}^{CP}=\left({D}^{+}\to \phi {\pi}^{+}\right)$. 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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DOE OSTI2022

Constraints on the CKM angle γ from B ± → Dh ± decays using D → h ± h' ∓ π 0 final states

A data sample collected with the LHCb detector corresponding to an integrated luminosity of 9 fb –1 is used to measure eleven CP violation observables in B ± → Dh ± decays, where h is either a kaon or a pion. The neutral D meson decay is reconstructed in the three-body final states: K ± π ∓ π o ; π + π – π o ; K + K – π o and the suppressed π ± K ∓ π o combination. The mode where a large CP asymmetry is expected, B ± → [π ± K ∓ π o ] D K ± , is observed with a significance greater than seven standard deviations. The ratio of the partial width of this mode relative to that of the favoured mode, B ± → [K ± π ∓ π o ] D K ± , is R ADS(K) = (1.27 ± 0.16 ± 0.02) × 10 –2 . Evidence for a large CP asymmetry is also seen: A ADS(K) = –0.38 ± 0.12 ± 0.02. Constraints on the CKM angle γ are calculated from the eleven reported observables.

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DOE OSTI2022

Precision measurement of forward $\mathrm{Z}$ boson production in proton-proton collisions at $ \sqrt{s}$ = 13 TeV

A precision measurement of the Z boson production cross-section at $\sqrt{s}$ = 13 TeV in the forward region is presented, using pp collision data collected by the LHCb detector, corresponding to an integrated luminosity of 5.1 fb –1 The production cross-section is measured using $\mathrm{Z}$ →$μ^+μ^-$ events within the fiducial region defined as pseudorapidity 2.0 < η < 4.5 and transverse momentum p T > 20 GeV/c for both muons and dimuon invariant mass 60 , M $_{μμ}$ < 120 GeV/c 2 . The integrated cross-section is determined to be $σ(Z → μ^+μ^-)$ = 196.4 ± 0.2 ± 1.6 ± 3.9 pb, where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measured results are in agreement with theoretical predictions within uncertainties.

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DOE OSTI2022

Observation of an exotic narrow doubly charmed tetraquark

Conventional, hadronic matter consists of baryons and mesons made of three quarks and a quark–antiquark pair, respectively. Here, we report the observation of a hadronic state containing four quarks in the Large Hadron Collider beauty experiment. This so-called tetraquark contains two charm quarks, a $\overline{{{{{u}}}}}$ and a $\overline{{{{{d}}}}}$ quark. This exotic state has a mass of approximately 3,875 MeV and manifests as a narrow peak in the mass spectrum of D 0 D 0 π + mesons just below the D *+ D 0 mass threshold. The near-threshold mass together with the narrow width reveals the resonance nature of the state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2022

Search for the decay $B^0$ → $\phiμ^+μ^–$

A search for the decay $B^0$ → $\phiμ^+μ^–$ is performed using proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV collected by the LHCb experiment and corresponding to an integrated luminosity of 9 fb –1 . No evidence for the $B^0$ → $\phiμ^+μ^–$ decay is found and an upper limit on the branching fraction, excluding the $\phi$ and charmonium regions in the dimuon spectrum, of 4.4 × 10 –3 at a 90% credibility level, relative to that of the $B^0_s$ → $\phiμ^+μ^–$ branching fraction and assuming a phase-space model, the absolute branching fraction of the $B^0$ → $\phiμ^+μ^–$ in the full q 2 range is determined to be less than 3.2 x 10 –9 at a 90% credibility level.

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DOE OSTI2022

Observation of the doubly charmed baryon decay $Ξ_{cc}^{++}$ →$Ξ_c^{'+}π^+$

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 $Ξ_c^{'+}$ →$Ξ^+_cγ$ decay is not reconstructed and the $ρK^-π^+$ 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.

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DOE OSTI2022

Search for massive long-lived particles decaying semileptonically at ${\sqrt{s}}=13\,\hbox {TeV}$

A search is performed for massive long-lived particles (LLPs) decaying semileptonically into a muon and two quarks. Two kinds of LLP production processes were considered. In the first, a Higgs-like boson with mass from 30 to 200\,GeV\!/c 2 is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10\,GeV\!/c 2 up to about one half the Higgs-like boson mass. The second LLP production mode is directly from quark interactions, with LLP masses from 10 to 90\,GeV\!/c 2 . The LLP lifetimes considered range from 5 to 200 ps. This study uses LHCb data collected from proton-proton collisions at $\sqrt{s}$=13\,TeV, corresponding to an integrated luminosity of 5.4\,fb -1 . No evidence of these long-lived states has been observed, and upper limits on the production cross-section times branching ratio have been set for each model considered.

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DOE OSTI2022

Study of charmonium and charmonium-like contributions in $\mathrm{B}^+$ → $\mathrm{J/ψηK^+}$ decays

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 ψ 2 (3823) → J/ψη decay.

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DOE OSTI2022

Observation of $Λ^0_b$ → $D^+ρπ^-π^-$ and $Λ^0_b$ → $D^{*+}ρπ^-π^-$ decays

The multihadron decays $Λ^0_b$ → $D+ρπ-π-$ and $Λ^0_b$ → $D^*+ρπ-π-$ are observed in data corresponding to an integrated luminosity of 3 fb -1 , collected in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV by the LHCb detector. Using the decay $Λ^0_b$ → $Λ^+_cπ^+π^-π^-$ as a normalisation channel, the ratio of branching fractions is measured to be $\frac {\mathcal{B} ( Λ^0_b → D^+ρπ^-π^-)} {\mathcal{B} (Λ^0_b → Λ^0_cπ^+π^-π^-)}$ x $\frac{\mathcal{B} (D^+ → K^-π^+π^+)} {\mathcal{B}(Λ^o_c → ρK^-π^-)}$ = (%.35 ± 0.21 ± 0.16)%, where the first uncertainty is statistical and the second systematic. The ratio of branching fractions for the $Λ^0_b$ → $D^{*+}ρπ^-π^-$ and $Λ^0_b$ → $D^+ρπ^-π^-$ decays is found to be $\frac {\mathcal{B} ( Λ^0_b → D^{*+}ρπ^-π^-)} {\mathcal{B} (Λ^0_b → D^+ρπ^-π^-)}$ X ($\mathcal{B} (D^{*+}→ D^+π^0)$ + $\mathcal{B} (D^{*+}→ D^+γ)$) = (61.3 ± 4.3 ± 4.0)%.

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DOE OSTI2022

Searches for rare ${B}_s^0$ and $B^0$ decays into four muons

Searches for rare ${B}_s^0$ and $B^0$ decays into four muons are performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb –1 . Direct decays and decays via light scalar and $J/ψ$ resonances are considered. No evidence for the six decays searched for is found and upper limits at the 95% confidence level on their branching fractions ranging between 1.8 x 10 –10 and 2.6 x 10 –9 are set.

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DOE OSTI2022

Measurement of $χ_{c1}$(3872) production in proton-proton collisions at $\sqrt{s}$ = 8 and 13 TeV

The production cross-section of the $χ_{c1}$(3872) state relative to the $ψ(2S)$ meson is measured using proton-proton collision data collected with the LHCb experiment at centre-of-mass energies of $\sqrt{s}$ = 8 and 13 TeV, corresponding to integrated luminosities of 2.0 and 5.4 fb -1 , respectively. The two mesons are reconstructed in the $J/ψπ^+π^-$ final state. The ratios of the prompt and nonprompt $χ_{c1}$(3872) to $ψ(2S)$ production cross-sections are measured as a function of transverse momentum, $ρ_T$, and rapidity, y, of the $χ_{c1}$(3872) and $ψ(2S)$ states, in the kinematic range 4 < $ρ_T$ < 20 GeV/c and 2.0< y < 4.5. The prompt ratio is found to increase with $ρ_T$, independently of y. For the prompt component, the double ratio of the $χ_{c1}$(3872) and $ψ(2S)$ production cross-sections between 13 and 8 TeV is observed to be consistent with unity, independent of $ρ_T$ and centre-of-mass energy.

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DOE OSTI2022

Search for the radiative $Ξ_b^{-}$ → $Ξ^-γ$ decay

The first search for the rare radiative decay $Ξ_b^{-}$ → $Ξ^-γ$ is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb -1 . $Ξ_b^{-}$ → $Ξ^-J/ψ$ channel is used as normalization. No $Ξ_b^{-}$ → $Ξ^-γ$ signal is found and an upper limit of $\mathcal{B}$( $Ξ_b^{-}$ → $Ξ^-γ$) < 1.3 x 10 -4 at 95% confidence level is obtained.

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DOE OSTI2022

Study of $\mathrm{B}_{c}^{+}$ decays to charmonia and three light hadrons

Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb -1 collected with the LHCb detector, seven decay modes of the $B^+_c$ meson into a $J/ψ$ or $ψ(2S)$ meson and three charged hadrons, kaons or pions, are studied. The decays $B^+_c$ → $(ψ(2S)$ →J/$ψπ^+π^-$)$π^+$, $B^+_c$→$ψ(2S)π^+π^-π^+, B^+_c$→ J/$ψK^+π^-π^+$ and $B^+_c$ → J/$ψK^+K^-K^+$ are observed for the first time, and evidence for the $B^+_c$ →$ψ(2S)K^+K^-π^+$, decay is found, where J/ψ and $(ψ(2S)$ mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different $B^+_c$ decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.

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DOE OSTI2022

Measurement of the W boson mass

The W boson mass is measured using proton-proton collision data at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 1.7 fb -1 recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon $q/ρ_T$ distribution of a sample of W →$μv$ decays and the $\phi^*$ distribution of a sample of Z → $μμ$ decays the W boson mass is determined to be $m_w$ =80354±23 stat ±10 exp ±17 theory ±9 PDF MeV, where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.

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