Publications (1008)1349.63 Total impact
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ABSTRACT: Observations of exotic structures in the J/ψp channel, which we refer to as charmoniumpentaquark states, in Λ[0 over b] → J/ψK[superscript ]p decays are presented. The data sample corresponds to an integrated luminosity of 3 fb[superscript 1] acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis of the threebody final state reproduces the twobody mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/ψp mass spectrum, it is necessary to include two BreitWigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380 ± 8 ± 29 MeV and a width of 205 ± 18 ± 86 MeV, while the second is narrower, with a mass of 4449.8 ± 1.7 ± 2.5 MeV and a width of 39 ± 5 ± 19 MeV. The preferred J[superscript P] assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.  [Show abstract] [Hide abstract]
ABSTRACT: The resonant substructures of B[superscript 0] → [bar over D][superscript 0]π[superscript +]π[superscript ] decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb[superscript 1] of pp collisions collected by the LHCb detector is used. The branching fraction of the B[superscript 0] → [bar over D][superscript 0]π[superscript +]π[superscript ] decay in the region m([bar over D][superscript 0]π[superscript ±]) > 2.1 GeV/c[superscript 2] is measured to be (8.46 ± 0.14 ± 0.29 ± 0.40) × 10[superscript 4], where the first uncertainty is statistical, the second is systematic and the last arises from the normalization channel B[superscript 0] → D[superscript *](2010)[superscript ]π[superscript +]. The π[superscript +]π[superscript ] Swave components are modeled with the isobar and Kmatrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at m([bar over D][superscript 0]π[superscript ]) ≈ 2.8 GeV/c[superscript 2] is confirmed and its spinparity is determined for the first time as J[superscript P] = 3[superscript ]. The branching fraction, mass and width of this structure are determined together with those of the D[* over 0](2400)[superscript ] and D[* over 2](2460)[superscript ] resonances. The branching fractions of other B[superscript 0] → [bar over D][superscript 0]h[superscript 0] decay components with h[superscript 0] → π[superscript +]π[superscript ] are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B[superscript 0] → [bar over D][superscript 0]f[subscript 0](500), B[superscript 0] → [bar over D][superscript 0]f[subscript 0](980), B[superscript 0] → [bar over D][superscript 0][subscript p](1450), B[superscript 0] → D[* over 3](2760)[superscript ]π[superscript +] and the first evidence of B[superscript 0] → [bar over D][superscript 0]f[subscript 0](2020) are presented. 
Article: Quantum numbers of the X(3872) state and orbital angular momentum in its p[superscript 0]J/ψ decay
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ABSTRACT: Angular correlations in B[superscript +] → X(3872)K[superscript +] decays, with X(3872) → ρ[superscript 0]J/ψ, ρ[superscript 0] → π[superscript +]π[superscript ] and J/ψ → μ[superscript +]μ[superscript ], are used to measure orbital angular momentum contributions and to determine the J[superscript PC] value of the X(3872) meson. The data correspond to an integrated luminosity of 3.0 fb[superscript 1] of protonproton collisions collected with the LHCb detector. This determination, for the first time performed without assuming a value for the orbital angular momentum, confirms the quantum numbers to be J[superscript PC] = 1[superscript ++]. The X(3872) is found to decay predominantly through an S wave and an upper limit of 4% at 95% C.L. is set on the Dwave contribution.  [Show abstract] [Hide abstract]
ABSTRACT: The decay B0s → ψ(2S)K+π is observed using a data set corresponding to an integrated luminosity of 3.0fb1 collected by the LHCb experiment in pp collisions at centreofmass energies of 7 and 8 TeV. The branching fraction relative to the B0 → ψ(2S)K+π decay mode is measured to be, where fs/fd indicates the uncertainty due to the ratio of probabilities for a b quark to hadronise into a B0s or B0 meson. Using an amplitude analysis, the fraction of decays proceeding via an intermediate K*(892)0 meson is measured to be 0.645±0.049(stat)±0.049(syst) and its longitudinal polarisation fraction is 0.524±0.056(stat)±0.029(syst). The relative branching fraction for this component is determined to be. In addition, the mass splitting between the B0s and B0 mesons is measured as M(B0s)M(B0)=87.45±0.44(stat)±0.09(syst)MeV/c2.Physics Letters B 07/2015; 747. DOI:10.1016/j.physletb.2015.06.038 · 6.13 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The first observation of the B[s over 0] → η[superscript ′]η[superscript ′] decay is reported. The study is based on a sample of protonproton collisions corresponding to 3.0 fb[superscript 1] of integrated luminosity collected with the LHCb detector. The significance of the signal is 6.4 standard deviations. The branching fraction is measured to be [3.31 ± 0.64(stat) ± 0.28(syst) ± 0.12(norm)] × 10[superscript 5], where the third uncertainty comes from the B[superscript ±] → η[superscript ′]K[superscript ±] branching fraction that is used as a normalization. In addition, the charge asymmetries of B[superscript ±] → η[superscript ′]K[superscript ±] and B[superscript ±] → ϕK[superscript ±], which are control channels, are measured to be (0.2 ± 1.3)% and (+1.7 ± 1.3)%, respectively. All results are consistent with theoretical expectations.  [Show abstract] [Hide abstract]
ABSTRACT: The Dalitz plot distribution of B[superscript 0] → [bar over D][superscript 0]K[superscript +]π[superscript ] decays is studied using a data sample corresponding to 3.0 fb[superscript 1] of pp collision data recorded by the LHCb experiment during 2011 and 2012. The data are described by an amplitude model that contains contributions from intermediate K[superscript *](892)[superscript 0], K[superscript *](1410)[superscript 0], K[* over 2](1430)[superscript 0] and D[* over 2](2460)[superscript ] resonances. The model also contains components to describe broad structures, including the K[* over 0](1430)[superscript 0] and D[* over 0](2400)[superscript ] resonances, in the Kπ Swave and the Dπ S and Pwaves. The masses and widths of the D[* over 0](2400)[superscript ] and D[* over 0](2460)[superscript ] resonances are measured, as are the complex amplitudes and fit fractions for all components included in the amplitude model. The model obtained will be an integral part of a future determination of the angle γ of the CabibboKobayashiMaskawa quark mixing matrix using B[superscript 0] → DK[superscript +]π[superscript ] decays.  [Show abstract] [Hide abstract]
ABSTRACT: Measurements are presented of the CP violation observables S and C in the decays of B[superscript 0] and [bar over B][superscript 0] mesons to the J/ψK[0 over S] final state. The data sample corresponds to an integrated luminosity of 3.0 fb[superscript 1] collected with the LHCb experiment in protonproton collisions at centerofmass energies of 7 and 8 TeV, and contains a total of 41 560 selected B[superscript 0] and [bar over B][superscript 0] decays. The analysis of the time evolution of these decays yields S = 0.731 ± 0.035(stat) ± 0.020(syst) and C = 0.038 ± 0.032(stat) ± 0.005(syst). In the standard model, S equals sin(2β) to a good level of precision. The values are consistent with the current world averages and with the standard model expectations.  European Physical Journal C 07/2015; 75(7). DOI:10.1140/epjc/s100520153502x · 5.08 Impact Factor

Article: Measurement of the exclusive Υ production crosssection in pp collisions at s = 7 TeV and 8 TeV
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ABSTRACT: A study is presented of central exclusive production of $\Upsilon(nS)$ states, where the $\Upsilon(nS)$ resonances decay to the $\mu^+\mu^$ final state, using $pp$ collision data recorded by the LHCb experiment. The crosssection is measured in the rapidity range $2<y(\Upsilon)<4.5$ where the muons are reconstructed in the pseudorapidity range $2<\eta(\mu^\pm)<4.5$. The data sample corresponds to an integrated luminosity of 2.9 fb$^{1}$ and was collected at centreofmass energies of $7$ TeV and $8$ TeV. The measured $\Upsilon(1S)$ and $\Upsilon(2S)$ production crosssections are \begin{eqnarray} \sigma(pp \to p\Upsilon(1S)p) &=& 9.0 \pm 2.1 \pm 1.7\textrm{ pb and}\nonumber\\ \sigma(pp \to p\Upsilon(2S)p) &=& 1.3 \pm 0.8 \pm 0.3\textrm{ pb},\nonumber \end{eqnarray} where the first uncertainties are statistical and the second are systematic. The $\Upsilon(1S)$ crosssection is also measured as a function of rapidity and is found to be in good agreement with Standard Model predictions. An upper limit is set at 3.4 pb at the 95\% confidence level for the exclusive $\Upsilon(3S)$ production crosssection, including possible contamination from $\chi_b(3P)\to\Upsilon(3S)\gamma$ decays.Journal of High Energy Physics 05/2015; 2015(9). DOI:10.1007/JHEP09(2015)084 · 6.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The standard model of particle physics describes the fundamental particles and their interactions via the strong, electromagnetic and weak forces. It provides precise predictions for measurable quantities that can be tested experimentally. The probabilities, or branching fractions, of the strangeB meson (B0s ) andtheB0meson decaying into two oppositely charged muons (μ+ and μ) are especially interesting because of their sensitivity to theories that extend the standard model. The standard model predicts that the B0s→μ+μ and B0s→μ+μ decays are very rare, with about four of the former occurring for every billion B0s mesons produced, and one of the latter occurring for every ten billion B0 mesons1. A difference in the observed branching fractions with respect to the predictions of the standard model would provide a direction in which the standard model should be extended. Before the Large Hadron Collider (LHC) at CERN2 started operating, no evidence for either decay mode had been found. Upper limits on the branching fractions were an order of magnitude above the standard model predictions. The CMS (CompactMuonSolenoid) andLHCb(LargeHadronCollider beauty) collaborations have performed a joint analysis of the data from proton'proton collisions that they collected in 2011 at a centreofmass energy of seven teraelectronvolts and in 2012 at eight teraelectronvolts. Here we report the first observation of the B0s→μ+μ decay, with a statistical significance exceeding six standard deviations, and the best measurement so far of its branching fraction. Furthermore, we obtained evidence for the B0s→μ+μ decay with a statistical significance of three standard deviations. Both measurements are statistically compatible with standard model predictions and allow stringent constraints to be placed on theories beyond the standardmodel. The LHCexperimentswill resume taking data in 2015, recording proton'proton collisions at a centreofmass energy of 13 teraelectronvolts, which will approximately double the production rates of B0s and B0 mesons and lead to further improvements in the precision of these crucial tests of the standard model.Nature 05/2015; 522(7554). DOI:10.1038/nature14474 · 41.46 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A search for $B_s^0 \to \overline{D}^{0} f_{0}(980)$ decays is performed using $3.0\, {\rm fb}^{1}$ of $pp$ collision data recorded by the LHCb experiment during 2011 and 2012. The $f_{0}(980)$ meson is reconstructed through its decay to the $\pi^{+}\pi^{}$ final state in the mass window $900\, {\rm MeV}/c^{2} < m(\pi^{+}\pi^{}) < 1080\, {\rm MeV}/c^{2}$. No significant signal is observed. The first upper limits on the branching fraction of $\mathcal{B}(B_s^0 \to \overline{D}^{0} f_{0}(980)) < 3.1\,(3.4) \times 10^{6}$ are set at $90\,\%$ ($95\,\%$) confidence level.Journal of High Energy Physics 05/2015; 2015(8). DOI:10.1007/JHEP08(2015)005 · 6.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The B[superscript ] → D[superscript +]K[superscript ]π[superscript ] decay is observed in a data sample corresponding to 3.0 fb^{1} of pp collision data recorded by the LHCb experiment during 2011 and 2012. Its branching fraction is measured to be B(B[superscript ] → D[superscript +]K[superscript ]π[superscript ]) = (7.31 ± 0.19 ± 0.22 ± 0.39) × 10[superscript 5] where the uncertainties are statistical, systematic and from the branching fraction of the normalization channel B[superscript ] → D[superscript +]π[superscript ]π[superscript ], respectively. An amplitude analysis of the resonant structure of the B[superscript ] → D[superscript +]K[superscript ]π[superscript ] decay is used to measure the contributions from quasitwobody B[superscript ] → D[* over 0](2400)[superscript 0]K[superscript ], B[superscript ] → D[* over 2](2460)[superscript 0]K[superscript ], and B[superscript ] → D[* over J](2760)[superscript 0]K[superscript ] decays, as well as from nonresonant sources. The D[* over J](2760)[superscript 0] resonance is determined to have spin 1.  [Show abstract] [Hide abstract]
ABSTRACT: Measurements are presented of the branching fractions of the decays B S 0 → D S ∓ K ∓ and B 0 → D S − K + relative to the decays B S 0 → D S − π + and B 0 → D − π +, respectively. The data used correspond to an integrated luminosity of 3.0 fb−1 of protonproton collisions. The ratios of branching fractions are $$ \frac{\mathrm{\mathcal{B}}\left({B}_{\mathrm{s}}^0\to {D}_{\mathrm{s}}^{\mp }{K}^{\mp}\right)}{\mathrm{\mathcal{B}}\left({B}_{\mathrm{s}}^0\to {D}_{\mathrm{s}}^{}{\pi}^{+}\right)}=0.0752\pm 0.0015\pm 0.0019 $$ and $$ \frac{\mathrm{\mathcal{B}}\left({B}^0\to {D}_{\mathrm{s}}^{}{K}^{+}\right)}{\mathrm{\mathcal{B}}\left({B}^0\to {D}^{}{\pi}^{+}\right)}=0.0129\pm 0.0005\pm 0.0008, $$ where the uncertainties are statistical and systematic, respectively.Journal of High Energy Physics 05/2015; 2015(5). DOI:10.1007/JHEP05(2015)019 · 6.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In the Standard Model of particle physics, the strength of the coupling of the $b$ quark to the $u$ quark, $V_{ub}$, is governed by the coupling of the quarks to the Higgs boson. Using data from the LHCb experiment at the Large Hadron Collider, it is shown that $V_{ub} = (3.27 \pm 0.23) \times 10^{3}$, from a measurement of $\Lambda^0_b \to p \mu^ \overline{\nu}_\mu$ decays. This is consistent with previous determinations of $V_{ub}$ using $B$ meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states. This measurement is the first ever to use a baryonic decay.Nature Physics 04/2015; 11(9). DOI:10.1038/nphys3415 · 20.15 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Production of B[+ over c] mesons in protonproton collisions at a centerofmass energy of 8 TeV is studied with data corresponding to an integrated luminosity of 2.0 fb[superscript 1] recorded by the LHCb experiment. The ratio of production cross sections times branching fractions between the B[+ over c] → J/ψπ[superscript +] and B[superscript +] → J/ψK[superscript +] decays is measured as a function of transverse momentum and rapidity in the regions 0 < p[subscript T] < 20 GeV/c and 2.0 < y < 4.5. The ratio in this kinematic range is measured to be (0.683 ± 0.018 ± 0.009)%, where the first uncertainty is statistical and the second systematic.  [Show abstract] [Hide abstract]
ABSTRACT: An angular analysis of the decay $B_s^0 \rightarrow K^{*0}\bar{K}{}^{*0}$ is performed using $pp$ collisions corresponding to an integrated luminosity of $1.0$ ${fb}^{1}$ collected by the LHCb experiment at a centreofmass energy $\sqrt{s} = 7$ TeV. A combined angular and mass analysis separates six helicity amplitudes and allows the measurement of the longitudinal polarisation fraction $f_L = 0.201 \pm 0.057 {(stat.)} \pm 0.040{(syst.)}$ for the $B_s^0 \rightarrow K^*(892)^0 \bar{K}{}^*(892)^0$ decay. A large scalar contribution from the $K^{*}_{0}(1430)$ and $K^{*}_{0}(800)$ resonances is found, allowing the determination of additional $CP$ asymmetries. Triple product and direct $CP$ asymmetries are determined to be compatible with the Standard Model expectations. The branching fraction $\mathcal{B}(B_s^0 \rightarrow K^*(892)^0 \bar{K}{}^*(892)^0)$ is measured to be $(10.6 \pm 1.8 {(stat.)} \pm 1.0 {(syst.)} \pm 0.6 (f_d/f_s) ) \times 10^{6}$.Journal of High Energy Physics 03/2015; 2015(7). DOI:10.1007/JHEP07(2015)166 · 6.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A measurement of the crosssection for Zboson production in the forward region of pp collisions at 8TeV centreofmass energy is presented. The measurement is based on a sample of $\rm Z\rightarrow e^+e^$ decays reconstructed using the LHCb detector, corresponding to an integrated luminosity of 2.0fb$^{1}$. The acceptance is defined by the requirements $2.0<\eta<4.5$ and $p_{\rm T}>20$GeV for the pseudorapidities and transverse momenta of the leptons. Their invariant mass is required to lie in the range 60120GeV. The crosssection is determined to be $$ \sigma({\rm pp\to Z\to e^+e^})=93.81\pm0.41({\rm stat})\pm1.48({\rm syst})\pm1.14({\rm lumi})\;{\rm pb}\,,$$ where the first uncertainty is statistical and the second reflects all systematic effects apart from that arising from the luminosity, which is given as the third uncertainty. Differential crosssections are presented as functions of the Zboson rapidity and of the angular variable $\phi^*$, which is related to the Zboson transverse momentum.Journal of High Energy Physics 03/2015; 2015(5). DOI:10.1007/JHEP05(2015)109 · 6.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Two structures are observed close to the kinematic threshold in the Ξ[0 over b]π[superscript ] mass spectrum in a sample of protonproton collision data, corresponding to an integrated luminosity of 3.0 fb[superscript 1], recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content bds are expected in this mass region: the spinparity J[superscript P] = ([1 over 2])[superscript +] and J[superscript P] = ([3 over 2])[superscript +] states, denoted Ξ'[subscript b][superscript ] and Ξ*[subscript b][superscript ]. Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m(Ξ'[subscript b][superscript ])  m(Ξ[0 over b])  m(π[superscript ]) = 3.653 ± 0.018 ± 0.006 [MeV over c [superscript 2]], m(Ξ[* over b])  m(Ξ[0 over b])  m(π[superscript ]) = 23.96 ± 0.12 ± 0.06 [MeV over c [superscript 2]], Γ(Ξ[* over b][superscript ]) = 1.65 ± 0.31 ± 0.10 MeV, where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ(Ξ'[subscript b][superscript ]) < 0.08 MeV at 95% confidence level. Relative production rates of these states are also reported.  [Show abstract] [Hide abstract]
ABSTRACT: Invariant mass distributions of B+pi and B0pi+ combinations are investigated in order to study excited B mesons. The analysis is based on a data sample corresponding to 3.0 fb1 of pp collision data, recorded by the LHCb detector at centreofmass energies of 7 and 8 TeV. Precise measurements of the masses and widths of the B_1(5721)^(0,+) and B_2*(5747)^(0,+) states are reported. Clear enhancements, particularly prominent at high pion transverse momentum, are seen over background in the mass range 58506000 MeV in both B+pi and B0pi+ combinations. The structures are consistent with the presence of four excited B mesons, labelled B_J(5840)^(0,+) and B_J(5960)^(0,+), whose masses and widths are obtained under different hypotheses for their quantum numbers. 
Article: Precision Measurement of CP Violation in B[0 over s] → J/ΨK[superscript +]K[superscript −] Decays
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ABSTRACT: The timedependent CP asymmetry in B[0 over s] → J/ψK[superscript +]K[superscript ] decays is measured using pp collision data, corresponding to an integrated luminosity of 3.0 fb[superscript 1], collected with the LHCb detector at centerofmass energies of 7 and 8 TeV. In a sample of 96 000 B[0 over s] → J/ψK[superscript +]K[superscript ] decays, the CPviolating phase ϕ[subscript s] is measured, as well as the decay widths Γ[subscript L] and Γ[subscript H] of the light and heavy mass eigenstates of the B[0 over s]–[bar over B][0 over s] system. The values obtained are ϕ[subscript s] = 0.058 ± 0.049 ± 0.006 rad, Γ[subscript s] ≡ (Γ[subscript L] + Γ[subscript H])/2 = 0.6603 ± 0.0027 ± 0.0015 ps[superscript 1], and ΔΓ[subscript s] ≡ Γ[subscript L]  Γ[subscript H] = 0.0805 ± 0.0091 ± 0.0032 ps[superscript 1], where the first uncertainty is statistical and the second, systematic. These are the most precise single measurements of those quantities to date. A combined analysis with B[0 over s] → J/ψπ[superscript +]π[superscript ] decays gives ϕ[subscript s] = 0.010 ± 0.039 rad. All measurements are in agreement with the standard model predictions. For the first time, the phase ϕ[subscript s] is measured independently for each polarization state of the K[superscript +]K[superscript ] system and shows no evidence for polarization dependence.
Publication Stats
5k  Citations  
1,349.63  Total Impact Points  
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Institutions

19922014

Universität Siegen
Siegen, North RhineWestphalia, Germany 
University of Freiburg
Freiburg, BadenWürttemberg, Germany


20122013

National Institute for Subatomic Physics
Amsterdamo, North Holland, Netherlands 
CERN
Genève, Geneva, Switzerland


2011

Tsinghua University
 Center for High Energy Physics
Peping, Beijing, China


2006

French National Centre for Scientific Research
 Unité Physique des particules
Lutetia Parisorum, ÎledeFrance, France


1982

Laboratoire de l'accélérateur linéaire
Orsay, ÎledeFrance, France
