Amplitude analysis and branching fraction measurement of $$ {B}^{+}\to {D}^{\ast -}{D}_s^{+}{\pi}^{+} $$ decays

Journal of High Energy Physics · 2024 · 1 citations

• Computer Science
• Algorithm
• Physics

A bstract The decays of the B + meson to the final state $$ {D}^{\ast -}{D}_s^{+}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> are studied in proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb − 1 . The ratio of branching fractions of the $$ {B}^{+}\to {D}^{\ast -}{D}_s^{+}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>B</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> and $$ {B}^0\to {D}^{\ast -}{D}_s^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>B</mml:mi> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:math> decays is measured to be 0 . 173 ± 0 . 006 ± 0 . 010, where the first uncertainty is statistical and the second is systematic. Using partially reconstructed $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mi>γ</mml:mi> </mml:math> and $$ {D}_s^{+}{\pi}^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mn>0</mml:mn> </mml:msup> </mml:math> decays, the ratio of branching fractions between the $$ {B}^{+}\to {D}^{\ast -}{D}_s^{\ast +}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>B</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> and $$ {B}^{+}\to {D}^{\ast -}{D}_s^{+}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>B</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> decays is determined as 1 . 31 ± 0 . 07 ± 0 . 14. An amplitude analysis of the $$ {B}^{+}\to {D}^{\ast -}{D}_s^{+}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>B</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> decay is performed for the first time, revealing dominant contributions from known excited charm resonances decaying to the D * − π + final state. No significant evidence of exotic contributions in the $$ {D}_s^{+}{\pi}^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mi>s</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:msup> <mml:mi>π</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> or $$ {D}^{\ast -}{D}_s^{+} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>∗</mml:mo>

Tracking of charged particles with nanosecond lifetimes at LHCb

The European Physical Journal C · 2024 · 1 citations

• Computer Science
• Algorithm
• Computer Science

Abstract A method is presented to reconstruct charged particles with lifetimes between $$10\,\text {ps} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mspace/> <mml:mtext>ps</mml:mtext> </mml:mrow> </mml:math> and $$10\,\text {ns},$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mspace/> <mml:mtext>ns</mml:mtext> <mml:mo>,</mml:mo> </mml:mrow> </mml:math> which considers a combination of their decay products and the partial tracks created by the initial charged particle. Using the $${\varXi } ^- $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>Ξ</mml:mi> </mml:mrow> <mml:mo>-</mml:mo> </mml:msup> </mml:math> baryon as a benchmark, the method is demonstrated with simulated events and proton-proton collision data at $$\sqrt{s} =13\,\text {TeV},$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mspace/> <mml:mtext>TeV</mml:mtext> <mml:mo>,</mml:mo> </mml:mrow> </mml:math> corresponding to an integrated luminosity of 2.0 $$\,\text {fb} ^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace/> <mml:msup> <mml:mtext>fb</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> collected with the LHCb detector in 2018. Significant improvements in the angular resolution and the signal purity are obtained. The method is implemented as part of the LHCb Run 3 event trigger in a set of requirements to select detached hyperons. This is the first demonstration of the applicability of this approach at the LHC, and the first to show its scaling with instantaneous luminosity.

Measurement of the W boson mass

Journal of High Energy Physics · 2022 · 107 citations

• Computer Science
• Physics
• Algorithm

A bstract The W boson mass is measured using proton-proton collision data at $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt></mml:math> = 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/p T distribution of a sample of W → μν decays and the ϕ * distribution of a sample of Z → μμ decays the W boson mass is determined to be $$ {m}_w=80354\pm {23}_{\mathrm{stat}}\pm {10}_{\mathrm{exp}}\pm {17}_{\mathrm{theory}}\pm {9}_{\mathrm{PDF}}\mathrm{MeV}, $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>m</mml:mi><mml:mi>w</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mn>80354</mml:mn><mml:mo>±</mml:mo><mml:msub><mml:mn>23</mml:mn><mml:mtext>stat</mml:mtext></mml:msub><mml:mo>±</mml:mo><mml:msub><mml:mn>10</mml:mn><mml:mi>exp</mml:mi></mml:msub><mml:mo>±</mml:mo><mml:msub><mml:mn>17</mml:mn><mml:mtext>theory</mml:mtext></mml:msub><mml:mo>±</mml:mo><mml:msub><mml:mn>9</mml:mn><mml:mi>PDF</mml:mi></mml:msub><mml:mi>MeV</mml:mi><mml:mo>,</mml:mo></mml:math> 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.

Test of lepton universality in beauty-quark decays

Nature Physics · 2022 · 367 citations

• Physics
• Particle physics
• Nuclear physics

Abstract The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons.

Analysis of Neutral <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi></mml:math>-Meson Decays into Two Muons

Physical Review Letters · 2022 · 94 citations

• Physics
• Particle physics
• Nuclear physics

Branching fraction and effective lifetime measurements of the rare decay B 0 s -and searches for the decays B 0 -and B 0 s - 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 . The branching fraction BB 0 s - 3.09 0.460.15 -0.43-0.11 10 -9 and the effective lifetime B 0 s - 2.07 AE 0.29 AE 0.03 ps are measured, where the first uncertainty is statistical and the second systematic. No significant signal for B 0 -and B 0 s - decays is found and upper limits BB 0 - < 2.6 10 -10 and BB 0 s - < 2.0 10 -9 at the 95% C.L. are determined, where the latter is limited to the range m > 4.9 GeV=c 2 . The results are in agreement with the standard model expectations.

Prediction of disability-free survival in healthy older people

GeroScience · 2022 · 34 citations

• Medicine
• Physical therapy
• Gerontology

Prolonging survival in good health is a fundamental societal goal. However, the leading determinants of disability-free survival in healthy older people have not been well established. Data from ASPREE, a bi-national placebo-controlled trial of aspirin with 4.7 years median follow-up, was analysed. At enrolment, participants were healthy and without prior cardiovascular events, dementia or persistent physical disability. Disability-free survival outcome was defined as absence of dementia, persistent disability or death. Selection of potential predictors from amongst 25 biomedical, psychosocial and lifestyle variables including recognized geriatric risk factors, utilizing a machine-learning approach. Separate models were developed for men and women. The selected predictors were evaluated in a multivariable Cox proportional hazards model and validated internally by bootstrapping. We included 19,114 Australian and US participants aged ≥65 years (median 74 years, IQR 71.6-77.7). Common predictors of a worse prognosis in both sexes included higher age, lower Modified Mini-Mental State Examination score, lower gait speed, lower grip strength and abnormal (low or elevated) body mass index. Additional risk factors for men included current smoking, and abnormal eGFR. In women, diabetes and depression were additional predictors. The biased-corrected areas under the receiver operating characteristic curves for the final prognostic models at 5 years were 0.72 for men and 0.75 for women. Final models showed good calibration between the observed and predicted risks. We developed a prediction model in which age, cognitive function and gait speed were the strongest predictors of disability-free survival in healthy older people.Trial registration Clinicaltrials.gov (NCT01038583).

Evidence of a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1770.svg"> <mml:mi>J</mml:mi> <mml:mo>/</mml:mo> <mml:mi>ψ</mml:mi> <mml:mi mathvariant="normal">Λ</mml:mi> </mml:math> structure and observation of excited <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si176.svg"> <mml:msup> <mml:mi mathvariant="normal">Ξ</mml:mi> <mml:mo>-</mml:mo> </mml:msup> </mml:math> states in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si177.svg"> <mml:msubsup> <mml:mi mathvariant="normal">Ξ</mml:mi> <mml:mi>b</mml:mi> <mml:mo>-</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:mi>J</mml:mi> <mml:mo>/</mml:mo> <mml:mi>ψ</mml:mi> <mml:mi mathvariant="normal">Λ</mml:mi> <mml:msup> <mml:mi>K</mml:mi> <mml:mo>-</mml:mo> </mml:msup> </mml:math> decay

Science Bulletin · 2021 · 246 citations

• Physics
• Particle physics
• Nuclear physics

, collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.

Measurement of the shape of the B-s(0) -> D-s*(-) mu(+) nu(mu) differential decay rate

2020

• Physics

The GlueX beamline and detector

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment · 2020 · 91 citations

• Physics
• Nuclear physics
• Optics

Measurement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:math>-Averaged Observables in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup><mml:mo stretchy="false">→</mml:mo><mml:msup><mml:mrow><mml:mi>K</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math> Decay

Physical Review Letters · 2020 · 291 citations

• Physics
• Particle physics
• Algorithm

An angular analysis of the B^{0}→K^{*0}(→K^{+}π^{-})μ^{+}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. The full set of CP-averaged observables are determined in bins of the invariant mass squared of the dimuon system. Contamination from decays with the K^{+}π^{-} system in an S-wave configuration is taken into account. The tension seen between the previous LHCb results and the standard model predictions persists with the new data. The precise value of the significance of this tension depends on the choice of theory nuisance parameters.