Engineering topics

Berninghoff, D.

Publications and source records attributed to Berninghoff, D..

At least 55 records · Page 3

DOE OSTI2023

Search for $D^{*}(2007)^{0} \rightarrow \mu ^{+} \mu ^{-}$ in $B^{-}\rightarrow \pi ^{-} \mu ^{+} \mu ^{-}$ decays

The very rare D* (2007) 0 → μ + μ – decay is searched for by analysing B – → μ + μ – decays. The analysis uses a sample of beauty mesons produced in proton–proton collisions collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb –1 . The signal signature corresponds to simultaneous peaks in the μ + μ – and π – μ + μ – invariant masses. No evidence for an excess of events over background is observed and an upper limit is set on the branching fraction of the decay at B (D* (2007) 0 → μ + μ – ) < 2.6 x 10 –8 at 90% confidence level. This is the first limit on the branching fraction of D* (2007) 0 → μ + μ – decays and the most stringent limit on D* (2007) 0 decays to leptonic final states. The analysis is the first search for a rare charm-meson decay exploiting production via beauty decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

${{J}/\psi }$ and ${{D}} ^0$ production in $\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5\,\text {GeV} $ PbNe collisions

The first measurement of ${{J}/\psi }$ and ${{D}} ^0$ production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of ${{J}/\psi }$ and ${{D}} ^0$ mesons is studied with a beam of lead ions with an energy of 2.5 TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5\,\text {GeV}$. The ${{J}/\psi }$/${{D}} ^0$ production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from $p\text {Ne}$ collisions at the same energy and show no difference in the observed ${{J}/\psi }$ suppression trend when comparing $p\text {Ne}$ and PbNe peripheral collisions with PbNe central collisions. Similar content being vie

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Nuclear Modification Factor of Neutral Pions in the Forward and Backward Regions in p - Pb Collisions

The nuclear modification factor of neutral pions is measured in proton-lead collisions collected at a center-of-mass energy per nucleon of 8.16 TeV with the LHCb detector. The π 0 production cross section is measured differentially in transverse momentum (p T ) for 1.5 < p Τ < 10.0 GeV and in center-of-mass pseudorapidity (η c.m. ) regions 2.5 < η c.m. < 3.5 (forward) and -4.0 < η c.m .< -3.0 (backward) defined relative to the proton beam direction. The forward measurement shows a sizable suppression of π 0 production, while the backward measurement shows the first evidence of π 0 enhancement in proton-lead collisions at the LHC. Together, these measurements provide precise constraints on models of nuclear structure and particle production in high-energy nuclear collisions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for direct CP violation in charged charmless B→PV decays

Measurements of C P asymmetry in charmless B → P V decays are presented, where P and V denote a pseudoscalar and a vector meson, respectively. Five different B → P V decays from four final states, B ± → π ± π + π - , B ± → K ± π + π - , B ± → K ± K + K - and B ± → π ± K + K - are analyzed. The measurements are based on a method that does not require full amplitude analyses, and are performed using proton-proton collision data at a center-of-mass energy of 13 TeV collected by LHCb between 2015 and 2018, corresponding to an integrated luminosity of 5.9 fb - 1 . In the π + π - P -wave, in the region dominated by the B ± → ρ ( 770 ) 0 K ± decay, a C P asymmetry of A C P = + 0.150 ± 0.019 ± 0.011 is measured, where the first uncertainty is statistical and the second is systematic. This is the first observation of C P violation in this process. For the other four decay channels, in regions dominated by the B ± → ρ ( 770 ) 0 π ± , B ± → K ( ¯ ) * ( 892 ) 0 π ± , B ± → K ( ¯ ) * ( 892 ) 0 K ± and B ± → Φ ( 1020 ) K ± decays, C P asymmetries in the P -wave compatible with zero are measured.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2023

Measurement of the CKM angle γ with B ± → D[K ∓ π ± π ± π ∓ ]h ± decays using a binned phase-space approach

The CKM angle γ is determined from CP-violating observables measured in B ± → D[K ∓ π ± π ± π ∓ ]h ± , (h = K, π) decays, where the measurements are performed in bins of the decay phase-space of the D meson. Using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 9 fb –1 , γ is determined to be $\gamma ={\left(54.8\begin{array}{c}+6.0\\ {}-5.8\end{array}\begin{array}{c}+0.6\\ {}-0.6\end{array}\begin{array}{c}+6.7\\ {}-4.3\end{array}\right)}^{\circ },$ where the first uncertainty is statistical, the second systematic and the third from the external inputs on the coherence factors and strong phases of the D-meson decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Observation of a J / ψ Λ Resonance Consistent with a Strange Pentaquark Candidate in B - → J / ψ Λ p ¯ Decays

An amplitude analysis of Β - → J/ψ⁢Λ⁢$\overline{p}$ decays is performed using 4400 signal candidates selected on a data sample of pp collisions recorded at center-of-mass energies of 7, 8, and 13 TeV with the LHCb detector, corresponding to an integrated luminosity of 9 fb -1 . A narrow resonance in the J/ψ⁢Λ system, consistent with a pentaquark candidate with strangeness, is observed with high significance. The mass and the width of this new state are measured to be 4338.2±0.7±0.4 MeV and 7.0±1.2±1.3 MeV, where the first uncertainty is statistical and the second systematic. The spin is determined to be 1/2 and negative parity is preferred. Because of the small Q-value of the reaction, the most precise single measurement of the B- mass to date, 5279.44±0.05±0.07 MeV, is obtained.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Charmonium production in $p$Ne collisions at $\sqrt{s_{\scriptscriptstyle \text {NN}}} =68.5$ GeV

The measurement of charmonium states produced in proton-neon (pNe) collisions by the LHCb experiment in its fixed-target configuration is presented. The pro duction of J/ψ and ψ(2S) mesons is studied with a beam of 2.5 TeV protons colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}}$ = 68.5 GeV. The data sample corresponds to an integrated luminosity of 21.7 ± 1.4 nb -1 . The J/ψ and ψ(2S) hadrons are reconstructed in μ + μ - final states. The J/ψ production cross-section per target nucleon in the centre-of mass rapidity range y* ϵ [-2.29, 0] is found to be 506 ± 8 ± 46 nb/nucleon. The ratio of J/ψ and D 0 cross-sections is evaluated to (1.06 ± 0.02 ± 0.09)%. The ψ(2S) to J/ψ relative production rate is found to be (1.67 ± 0.27 ± 0.10)% in good agreement with other measurements involving beam and target nuclei of similar sizes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of $\tau _\text {L}$ using the ${B} _s^0 \rightarrow J/\psi \eta$ decay mode

Using a proton–proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of $5.7~\text {fb}^{-1}$ , the lifetime of the light ${{B} ^0_{s}}$ mass eigenstate, $\tau _{L}$ , is measured using the $B^0_s \rightarrow J/\psi \eta$ decay mode to be $\begin{aligned} \tau _{\text {L}} = 1.445 \pm 0.016 \text {(stat)} \pm 0.008 \text {(syst)} \,\text {ps}. \end{aligned}$ A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb –1 of integrated luminosity gives $\begin{aligned} \tau _{\text {L}} = 1.452 \pm 0.014 \pm 0.007 \pm 0.002 \,\text {ps}, \end{aligned}$ where the first uncertainty is statistical, the second due to the uncorrelated part of the systematic uncertainty and the third due to the correlated part of the systematic uncertainty.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for the rare hadronic decay $B^0_s → p\overline{p}$

A search for the rare hadronic decay B s 0 → p p ¯ is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb - 1 . No evidence of the decay is found and an upper limit on its branching fraction is set at B ( B s 0 → p p ¯ ) < 4.4 ( 5.1 ) × 10 - 9 at 90% (95%) confidence level; this is currently the world’s best upper limit. The decay mode B 0 → p p ¯ is measured with very large significance, confirming the first observation by the LHCb experiment in 2017. The branching fraction is determined to be B ( B 0 → p p ¯ ) = ( 1.27 ± 0.15 ± 0.05 ± 0.04 ) × 10 - 8 , where the first uncertainty is statistical, the second is systematic and the third is due to the external branching fraction of the normalization channel B 0 → K + π - . The combination of the two LHCb measurements of the B 0 → p p ¯ branching fraction yields B ( B 0 → p p ¯ ) = ( 1.27 ± 0.13 ± 0.05 ± 0.03 ) × 10 - 8 .

Bottom mesons↗

DOE OSTI2023

Observation of the ${B}_s^0$ → D* + D* - decay

The first observation of the $B^{0}_{s}$ → D* + D* - decay and the measurement of its branching ratio relative to the B 0 → D* + D* - decay are presented. The data sample used corresponds to an integrated luminosit y of 9 fb -1 of proton-proton collisions recorded by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018. The decay is observed with more than 10 standard deviations and the time-integrated ratio of branching fractions is determined to be $\frac{\mathcal{B}(B^{0}_{s} → D*^+D*^-)}{\mathcal{B}(B^0 → D*^+D*^-)}$ = 0.269 ± 0.032 ± 0.011 ± 0.008, where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the fragmentation fraction ratio f s /f d . The $B^{0}_{s}$ → D* + D* - branching fraction is calculated to be $\mathcal{B}$ ($B^{0}_{s} → D*^+D*^-)$ = (2.15 ± 0.26 ± 0.09 ± 0.06 ± 0.16) X 10 -4 , where the fourth uncertainty is due to the B 0 → D* + D* - branching fraction. These results are calculated using the average $B^{0}_{s}$ meson lifetime in simulation. Correction factors are reported for scenarios where either a purely heavy or a purely light $B^{0}_{s}$ eigenstate is considered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Direct C P violation in charmless three-body decays of B ± mesons

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 ± →π ± ⁢K + K – decays is confirmed, and CP asymmetries are observed with a significance of more than five standard deviations in the B ± →π ± π + ⁢π – and B ± →K ± ⁢K + ⁢K – decays, while the CP asymmetry of B ± →K ± ⁢π + ⁢π – 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 ± →π ± ⁢χ c⁢0 ⁡(1⁢P) in both B ± →π ± π + ⁢π – and B ± →π ± ⁢K + ⁢K – decays is observed, as is CP violation involving these amplitudes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Observation of the ${\textrm{B}}_{\textrm{s}}^0$ → χ c1 (3872) π + π - decay

The first observation of the ${B}_s^0$ → ( Xc1 (3872) → J/ψπ + π - )π + π - decay is reported using proton-proton collision data, corresponding to integrated luminosities of 1, 2 and 6 fb -1 , collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The ratio of branching fractions relative to the ${B}_s^0$ → (ψ(2S) → J/ψπ + π - )π + π - decay is measured to be $\frac{\mathcal{B}(B^{0}_{s} → X_{c1}(3872)π^+π^-) x \mathcal{B} (X_{c1}(3872) → J/ψπ^+π^-)}{\mathcal{B}(B^0_{s} → ψ(2S)π^+π^-) X \mathcal{B} (ψ(2S) → Jψπ^+π^-)}$ = (6.8 ± 1.1 ± 0.2) x 10 -2 where the first uncertainty is statistical and the second systematic. The mass spectrum of the π + π - system recoiling against the Xc1 (3872) meson exhibits a large contribution from ${B}_s^0$ → Xc1 (3872) (f 0 (980) → π + π - ) decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of the ratio of branching fractions $\mathcal{B}\left({B}_c^{+}\to {B}_s^0{\pi}^{+}\right)/\mathcal{B}\left({B}_c^{+}\to J/\psi {\pi}^{+}\right)$

The ratio of branching fractions of ${B}_c^{+}\to {B}_s^0{\pi}^{+}$ and ${B}_c^{+}\to J/\psi {\pi}^{+}$ decays is measured with proton-proton collision data of a centre-of-mass energy of 13 TeV. The data were collected with the LHCb experiment during 2016–2018, corresponding to an integrated luminosity of 5.4 fb –1 . The ${B}_s^0$ mesons are reconstructed via the decays ${B}_s^0\to J/\psi \phi$ and ${B}_s^0\to {D}_s^{-}{\pi}^{+}$. The ratio of branching fractions is measured to be $\mathcal{B}\left({B}_c^{+}\to {B}_s^0{\pi}^{+}\right)/\mathcal{B}\left({B}_c^{+}\to J/\psi {\pi}^{+}\right)=91\pm 10\pm 8\pm 3$ where the first uncertainty is statistical, the second is systematic and the third is due to the knowledge of the branching fractions of the intermediate state decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Search for CP violation in ${D}_{(s)}^{+}$ → K - K + K + decays

A search for direct CP violation in the Cabibbo-suppressed decay $ {D}_s^{+} $ → K - K + K + and in the doubly Cabibbo-suppressed decay D + → K - K + K + is reported. The analysis is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 5.6 fb - 1 . The search is conducted by comparing the $ {D}_{(s)}^{+} $ and $ {D}_{(s)}^{-} $ Dalitz-plot distributions through a model-independent binned technique, based on fits to the K - K + K + invariant-mass distributions, with a total of 0.97 (1.27) million $ {D}_s^{+} $ ( D + ) signal candidates. The results are given as p -values for the hypothesis of CP conservation and are found to be 13.3% for the $ {D}_s^{+} $ → K - K + K + decay and 31.6% for the D + → K - K + K + decay. No evidence for CP violation is observed in these decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of Υ production in pp collisions at $\sqrt{s}$ = 5 TeV

The production cross-sections of Υ mesons, namely Υ(1S), Υ(2S) and Υ(3S), in pp collisions at $\sqrt{s}$ = 5 TeV are measured with a data sample corresponding to an integrated luminosity of 9.13 ± 0.18 pb –1 collected by the LHCb detector. The Υ mesons are reconstructed in the decay mode Υ → μ + μ – . Double differential cross-sections times branching fractions, as functions of the transverse momentum p T and the rapidity y of the Υ mesons, are measured in the range p T < 20 GeV/c and 2.0 < y < 4.5. The results integrated over these p T and y ranges are $\sigma \left(\textrm{Y}(1S)\right)\times \mathcal{B}\left(\textrm{Y}(1S)\to {\mu}^{+}{\mu}^{-}\right)=2101\pm 33\pm 83\ \textrm{pb},$ $\sigma \left(\textrm{Y}(2S)\right)\times \mathcal{B}\left(\textrm{Y}(2S)\to {\mu}^{+}{\mu}^{-}\right)=526\pm 20\pm 21\ \textrm{pb},$ $\sigma \left(\textrm{Y}(3S)\right)\times \mathcal{B}\left(\textrm{Y}(3S)\to {\mu}^{+}{\mu}^{-}\right)=242\pm 16\pm 10\ \textrm{pb},$ where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different Υ states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of Υ(1S) at $\sqrt{s}$ = 5 TeV is updated as well using the directly measured cross-section results from this analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

A study of $CP$ violation in the decays $B^±$ → [$K^+ K^-π^+π^-$]$_Dh^±$ ($h$ = $K, π$) and $B^±$ → [$π^+π^-π^+π^-$]$_Dh^±$

The first study of CP violation in the decay mode $B^±$ → [$K^+ K^-π^+π^-$]$_Dh^±$, with $h$ = $K, π$, is presented, exploiting a data sample of proton–proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of 9 fb -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 γ 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 $B^±$ → [$K^+ K^-π^+π^-$]$_Dh^±$ and $B^±$ → [$π^+π^-π^+π^-$]$_Dh^±$ decays.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2023

Open charm production and asymmetry in p Ne collisions at $\sqrt{s_{\scriptscriptstyle {\textrm{NN}}}}$ = 68.5 GeV

A measurement of D 0 meson production by the LHCb experiment in its fixed-target configuration is presented. The production of D 0 mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of $\sqrt{s_{NN}}$ = 68.5 GeV. The sum of the D 0 and $\overline{D}$ 0 production cross-section in pNe collisions in the centre-of-mass rapidity range y* ϵ [-2.29,0] is found to be $σ^{y* ϵ [-2.29,0]}_{D^0}$ = 48.2 ± 0.3 ± 4.5 μb/nucleon where the first uncertainty is statistical and the second is systematic. The D 0 and $\overline{D}$ 0 production asymmetry is also evaluated and suggests a trend towards negative values at large negative y*. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1% intrinsic charm and 10% recombination contributions better describe the data than the other models considered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of antiproton production from antihyperon decays in ${p} \textrm{He}$ collisions at $\sqrt{s_{\scriptscriptstyle \mathrm NN}} =110$ GeV

The interpretation of cosmic antiproton flux measurements from space-borne experiments is currently limited by the knowledge of the antiproton production cross-section in collisions between primary cosmic rays and the interstellar medium. Using collisions of protons with an energy of 6.5 TeV incident on helium nuclei at rest in the proximity of the interaction region of the LHCb experiment, the ratio of antiprotons originating from antihyperon decays to prompt production is measured for antiproton momenta between 12 and 110 GeV/c. The dominant antihyperon contribution, namely ${\overline{\varLambda }} \rightarrow {\overline{{p}}} {{\pi } ^+}$ decays from promptly produced $\overline{\varLambda }$ particles, is also exclusively measured. The results complement the measurement of prompt antiproton production obtained from the same data sample. At the energy scale of this measurement, the antihyperon contributions to antiproton production are observed to be significantly larger than predictions of commonly used hadronic production models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗