R. J. Barlow
A5107251665- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Particle Accelerators and Free-Electron Lasers
- Computational Physics and Python Applications
- Black Holes and Theoretical Physics
- Medical Imaging Techniques and Applications
- Atomic and Subatomic Physics Research
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Nuclear physics research studies
- Cosmology and Gravitation Theories
- Radiation Detection and Scintillator Technologies
- Radiation Therapy and Dosimetry
- Nuclear reactor physics and engineering
- Astrophysics and Cosmic Phenomena
- Stochastic processes and statistical mechanics
- Distributed and Parallel Computing Systems
- Muon and positron interactions and applications
- International Science and Diplomacy
- Advanced Data Storage Technologies
University of Manchester
2016-2025
University of Huddersfield
2015-2024
University of Oxford
1979-2023
European Organization for Nuclear Research
1990-2020
Institute of Nuclear and Particle Physics
2005-2019
Centro Brasileiro de Pesquisas Físicas
2013-2019
Laboratoire d’Annecy de Physique des Particules
2002-2018
Institut National de Physique Nucléaire et de Physique des Particules
2017-2018
Centre National de la Recherche Scientifique
2017-2018
Universitat de Barcelona
2018
Observations of exotic structures in the J/ψp channel, which we refer to as charmonium-pentaquark states, Λ0b→J/ψK−p decays are presented. The data sample corresponds an integrated luminosity 3 fb−1 acquired with LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis three-body final state reproduces two-body mass angular distributions. To obtain a satisfactory fit seen spectrum, it is necessary include two Breit-Wigner amplitudes that each describe resonant state. significance...
A measurement of the ratio branching fractions $B^{+}\rightarrow K^{+}\mu^{+}\mu^{-}$ and K^{+}e^{+}e^{-}$ decays is presented using proton-proton collision data, corresponding to an integrated luminosity 3.0 fb$^{-1}$, recorded with LHCb experiment at center-of-mass energies 7 8 $\mathrm{\,Te\kern -0.1em V}$. The value for dilepton invariant mass squared range $1<q^{2}<6\mathrm{\,Ge\kern V^2\!/}c^4$ measured be $0.745^{+0.090}_{-0.074}\mathrm{\,(stat)}\,\pm0.036\mathrm{\,(syst)}$. This most...
The branching fraction ratio R(D^{*})≡B(B[over ¯]^{0}→D^{*+}τ^{-}ν[over ¯]_{τ})/B(B[over ¯]^{0}→D^{*+}μ^{-}ν[over ¯]_{μ}) is measured using a sample of proton-proton collision data corresponding to 3.0 fb^{-1} integrated luminosity recorded by the LHCb experiment during 2011 and 2012. tau lepton identified in decay mode τ^{-}→μ^{-}ν[over ¯]_{μ}ν_{τ}. semitauonic sensitive contributions from non-standard-model particles that preferentially couple third generation fermions, particular,...
The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) CERN. experiment designed for precision measurements of CP violation and rare decays beauty charm hadrons. In this paper performance various sub-detectors trigger system are described, using data taken from 2010 to 2012. It shown that design criteria have been met. excellent has allowed collaboration publish wide range physics results, demonstrating LHCb's unique role, both as heavy flavour general purpose in region.
A narrow pentaquark state, P_{c}(4312)^{+}, decaying to J/ψp, is discovered with a statistical significance of 7.3σ in data sample Λ_{b}^{0}→J/ψpK^{-} decays, which an order magnitude larger than that previously analyzed by the LHCb Collaboration. The P_{c}(4450)^{+} structure formerly reported confirmed and observed consist two overlapping peaks, P_{c}(4440)^{+} P_{c}(4457)^{+}, where this two-peak interpretation 5.4σ. proximity Σ_{c}^{+}D[over ¯]^{0} ¯]^{*0} thresholds peaks suggests they...
We present a measurement of form-factor-independent angular observables in the decay ${B}^{0}\ensuremath{\rightarrow}{K}^{*}(892{)}^{0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. The analysis is based on data sample corresponding to an integrated luminosity $1.0\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, collected by LHCb experiment $pp$ collisions at center-of-mass energy 7 TeV. Four are measured six bins dimuon invariant mass squared ${q}^{2}$ range...
Using Statistics. Describing the Data. Theoretical Distributions. Errors. Estimation. Least Squares. Probability and Confidence. Taking Decisions. Ranking Methods. Notes for Number Crunchers. Bibliography. Appendices. Index.
An angular analysis of the B 0 → K *0(→ + π −)μ μ − decay is presented. The dataset corresponds to an integrated luminosity 3.0 fb−1 pp collision data collected at LHCb experiment. complete information from used determine CP-averaged observables and CP asymmetries, taking account possible contamination decays with system in S-wave configuration. their correlations are reported bins q 2, invariant mass squared dimuon system. determined both unbinned maximum likelihood fit by using principal...
The title is a challenge. This an account of the development standard model particle physics, written not by physicist but historian. certainly suitable topic for historian to analyse, and one might anticipate refreshingly different from outsider sitting above fray. indeed what provided, though `refreshing' right word; viewpoint so that scientific reader will find it at best thought-provoking, worst unacceptable. For historian, presumably, history Standard Model be evaluated in same terms as...
A test of lepton universality, performed by measuring the ratio branching fractions $B^{0} \rightarrow K^{*0}\mu^{+}\mu^{-}$ and K^{*0}e^{+}e^{-}$ decays, $R_{K^{*0}}$, is presented. The $K^{*0}$ meson reconstructed in final state $K^{+}\pi^{-}$, which required to have an invariant mass within 100$\mathrm{\,MeV}c^2$ known $K^{*}(892)^{0}$ mass. analysis using proton-proton collision data, corresponding integrated luminosity about 3$\mathrm{\,fb}^{-1}$, collected LHCb experiment at...
A highly significant structure is observed in the $\Lambda_c^+K^-\pi^+\pi^+$ mass spectrum, where $\Lambda_c^+$ baryon reconstructed decay mode $pK^-\pi^+$. The consistent with originating from a weakly decaying particle, identified as doubly charmed $\Xi_{cc}^{++}$. difference between masses of $\Xi_{cc}^{++}$ and states measured to be $1334.94 \pm 0.72 (\mathrm{stat}) 0.27 (\mathrm{syst}~\mathrm{MeV}/c^2$, then determined $3621.40 (\mathrm{syst} 0.14 \, (\Lambda_c^+)~\mathrm{MeV}/c^2$,...
Resonant structures in B^{0}→ψ^{'}π^{-}K^{+} decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3 fb^{-1} collected with LHCb detector. The cannot be described K^{+}π^{-} resonances alone, which is confirmed model-independent approach. A highly significant Z(4430)^{-}→ψ^{'}π^{-} component required, thus confirming existence this state. observed evolution Z(4430)^{-} amplitude ψ^{'}π^{-} mass establishes resonant nature...
A search for the rare decays ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ is performed with data collected in 2011 2012 LHCb experiment at Large Hadron Collider. The samples comprise $1.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of proton-proton collisions $\sqrt{s}=8\text{ }\mathrm{TeV}$ $1.0\text{ $\sqrt{s}=7\text{ }\mathrm{TeV}$. We...
The quantum numbers of the X(3872) meson are determined to be JPC = 1++ based on angular correlations in B+ K+ decays, where pi+pi- J/psi and \mu+\mu-. data correspond 1.0 fb-1 pp collisions collected by LHCb detector. only alternative assignment allowed previous measurements, JPC=2-+, is rejected with a confidence level equivalent more than eight Gaussian standard deviations using likelihood-ratio test full phase space. This result favors exotic explanations state.
Abstract The standard model of particle physics currently provides our best description fundamental particles and their interactions. theory predicts that the different charged leptons, electron, muon tau, have identical electroweak interaction strengths. Previous measurements shown a wide range decays are consistent with this principle lepton universality. This article presents evidence for breaking universality in beauty-quark decays, significance 3.1 deviations, based on proton–proton...
The production of J/psi mesons in proton-proton collisions at sqrt(s)=7 TeV is studied with the LHCb detector LHC. differential cross-section for prompt measured as a function transverse momentum pT and rapidity y fiducial region 0<pT<14 GeV/c 2.0<y<4.5. fraction from b-hadron decays are also same ranges. analysis based on data sample corresponding to an integrated luminosity 5.2pb-1. cross-sections over 10.52 +/- 0.04 1.40 +1.64/-2.20 mub 1.14 0.01 0.16 decays, where first uncertainty...
The ratio of branching fractions R(D*−)≡B(B0→D*−τ+ντ)/B(B0→D*−μ+νμ) is measured using a data sample proton-proton collisions collected with the LHCb detector at center-of-mass energies 7 and 8 TeV, corresponding to an integrated luminosity 3 fb−1. For first time, R(D*−) determined τ-lepton decays three charged pions in final state. B0→D*−τ+ντ yield normalized that B0→D*−π+π−π+ mode, providing measurement B(B0→D*−τ+ντ)/B(B0→D*−π+π−π+)=1.97±0.13±0.18, where uncertainty statistical second...
The ratio of branching fractions ${\cal{R}}(D^{*-})\equiv {\cal{B}}(B^0 \to D^{*-} τ^+ ν_τ)/{\cal{B}}(B^0 μ^+ν_μ)$ is measured using a data sample proton-proton collisions collected with the LHCb detector at center-of-mass energies 7 and 8 TeV, corresponding to an integrated luminosity 3$~$fb$^{-1}$. $τ$ lepton reconstructed three charged pions in final state. A novel method used that exploits different vertex topologies signal backgrounds isolate samples semitauonic decays $b$ hadrons high...
A search for the rare decays ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ is performed at LHCb experiment. The data analyzed correspond to an integrated luminosity of $1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ $pp$ collisions a center-of-mass energy 7 TeV $2\text{ 8 TeV. An excess signal candidates with respect background expectation seen...
The $\Xi_c^+ K^-$ mass spectrum is studied with a sample of $pp$ collision data corresponding to an integrated luminosity 3.3 fb$^{-1}$, collected by the LHCb experiment. $\Xi_c^+$ reconstructed in decay mode $p K^- \pi^+$. Five new, narrow excited $\Omega_c^0$ states are observed: $\Omega_c(3000)^0$, $\Omega_c(3050)^0$, $\Omega_c(3066)^0$, $\Omega_c(3090)^0$, and $\Omega_c(3119)^0$. Measurements their masses widths reported.
Abstract Conventional, hadronic matter consists of baryons and mesons made three quarks a quark–antiquark pair, respectively 1,2 . Here, we report the observation state containing four in Large Hadron Collider beauty experiment. This so-called tetraquark contains two charm quarks, $$\overline{{{{{u}}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mrow> <mml:mi>u</mml:mi> </mml:mrow> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> $$\overline{{{{{d}}}}}$$...
A search for the rare decays B_{s}^{0}→μ^{+}μ^{-} and B^{0}→μ^{+}μ^{-} is performed at LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb^{-1}. An excess observed with significance 7.8 standard deviations, representing first observation this decay single experiment. The branching fraction measured be B(B_{s}^{0}→μ^{+}μ^{-})=(3.0±0.6_{-0.2}^{+0.3})×10^{-9}, where uncertainty statistical second systematic. measurement effective...