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EP Articles

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2017-11-21
11:13
Search for excited $B_c^+$ states / LHCb Collaboration
A search is performed in the invariant mass spectrum of the $B_c^{+}\pi^{+}\pi^{-}$ system for the excited $B_c^{+}$ states $B_c(2^{1}S_{0})^+$ and $B_c(2^{3}S_{1})^+$ using a data sample of $pp$ collisions collected by the LHCb experiment at the centre-of-mass energy of $\sqrt{s} = 8 \,{\mathrm{TeV}}$, corresponding to an integrated luminosity of $2 \,{\mathrm{fb^{-1}}}$. No evidence is seen for either state. [...]
CERN-EP-2017-306; LHCB-PAPER-2017-042; arXiv:1712.04094; LHCB-PAPER-2017-042.- Geneva : CERN, 2018-01-29 - 19 p. - Published in : JHEP 01 (2018) 138 Article from SCOAP3: PDF; Preprint: PDF; Supplementary information: ZIP; External link: Additional information for the analysis

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2017-11-16
09:10
First observation of $B^{+} \to D_s^{+}K^{+}K^{-}$ decays and a search for $B^{+} \to D_s^{+}\phi$ decays / LHCb Collaboration
A search for $B^{+} \to D_s^{+}K^{+}K^{-}$ decays is performed using $pp$ collision data corresponding to an integrated luminosity of 4.8 fb$^{-1}$, collected at centre-of-mass energies of 7, 8 and 13$\,$TeV with the LHCb experiment. A significant signal is observed for the first time and the branching fraction is determined to be \begin{equation*} \mathcal{B}(B^{+} \to D_s^{+}K^{+}K^{-} ) = (7.1 \pm 0.5 \pm 0.6 \pm 0.7) \times 10^{-6}, \end{equation*} where the first uncertainty is statistical, the second systematic and the third due to the uncertainty on the branching fraction of the normalisation mode $B^{+} \to D_s^{+} \overline{\kern -0.2em D}^{0}$. [...]
LHCB-PAPER-2017-032; CERN-EP-2017-289; arXiv:1711.05637; LHCB-PAPER-2017-032.- Geneva : CERN, 2018-01-26 - 22 p. - Published in : JHEP 01 (2018) 131 Article from SCOAP3: PDF; Preprint: PDF; Related data file(s): ZIP;

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2017-10-17
16:52
Measurement of the $B^{\pm}$ production cross-section in pp collisions at $\sqrt{s} =$ 7 and 13 TeV / LHCb Collaboration
The production of $B^{\pm}$ mesons is studied in $pp$ collisions at centre-of-mass energies of 7 and 13 TeV, using $B^{\pm}\rightarrow J/\psi K^{\pm}$ decays and data samples corresponding to 1.0 fb$^{-1}$ and 0.3 fb$^{-1}$, respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range $0<p_{\text{T}}< 40$ GeV/$c$ and the rapidity range $2.0<y<4.5$ are measured to be $\sigma(pp \rightarrow B^{\pm} X, \sqrt{s} = \text{7 TeV}) = 43.0 \pm 0.2 \pm 2.5 \pm 1.7\mu b,$ $\sigma(pp \rightarrow B^{\pm} X, \sqrt{s} = \text{13 TeV}) = 86.6 \pm 0.5 \pm 5.4 \pm 3.4\mu b,$ where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the $B^{\pm}\rightarrow J/\psi K^{\pm}$ branching fraction. [...]
CERN-EP-2017-254; LHCB-PAPER-2017-037; arXiv:1710.04921; LHCB-PAPER-2017-037.- Geneva : CERN, 2017 - 22 p. - Published in : JHEP 1712 (2017) 026 Article from SCOAP3: PDF; Preprint: 1710.04921 - PDF; arXiv:1710.04921 - PDF; Related data file(s): ZIP;

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2017-10-09
10:08
Search for dark photons produced in 13 TeV $pp$ collisions / LHCb Collaboration
Searches are performed for both prompt-like and long-lived dark photons, $A^{\prime}$, produced in proton-proton collisions at a center-of-mass energy of 13 TeV, using $A^{\prime}\to\mu^+\mu^-$ decays and a data sample corresponding to an integrated luminosity of 1.6 fb$^{-1}$ collected with the LHCb detector. The prompt-like $A^{\prime}$ search covers the mass range from near the dimuon threshold up to 70 GeV, while the long-lived $A^{\prime}$ search is restricted to the low-mass region $214<m(A^{\prime})<350$ MeV. [...]
LHCB-PAPER-2017-038; CERN-EP-2017-248; arXiv:1710.02867; LHCB-PAPER-2017-038.- Geneva : CERN, 2018-02-09 - 11 p. - Published in : Phys. Rev. Lett. 120 (2018) 061801 Article from SCOAP3: PDF; Preprint: PDF; Related data file(s): ZIP;

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2017-09-18
16:32
Measurement of $CP$ observables in $B^{\pm} \rightarrow D K^{*\pm}$ decays using two- and four-body $D$ final states / LHCb Collaboration
Measurements of $CP$ observables in $B^{\pm} \rightarrow D K^{*\pm}$ decays are presented, where $D$ denotes a superposition of $D^0$ and $\overline{D^0}$ meson states. Decays of the $D$ meson to $K^{-}\pi^{+}$, $K^{-}K^{+}$, $\pi^{-}\pi^{+}$, $K^{-}\pi^{+}\pi^{-}\pi^{+}$ and $\pi^{-}\pi^{+}\pi^{-}\pi^{+}$ are used and the $K^{*\pm}$ meson is reconstructed in the $K^{0}_{\mathrm{S}}\pi^{\pm}$ final state. [...]
LHCB-PAPER-2017-030; CERN-EP-2017-208; arXiv:1709.05855; LHCB-PAPER-2017-030.- Geneva : CERN, 2017-11-23 - 27 p. - Published in : JHEP 11 (2017) 156 Article from SCOAP3: PDF; Preprint: PDF; Related data file(s): ZIP;

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2017-09-15
14:53
Precise measurement of the $\chi_{c1}$ and $\chi_{c2}$ resonance parameters with the decays $\chi_{c1,c2}\to J/\psi\mu^+\mu^-$ / LHCb Collaboration
The decays $\chi_{c1} \rightarrow J/\psi \mu^+ \mu^-$ and $\chi_{c2} \rightarrow J/\psi \mu^+ \mu^-$ are observed and used to study the resonance parameters of the $\chi_{c1}$ and $\chi_{c2}$ mesons. The masses of these states are measured to be m(\chi_{c1}) = 3510.71 \pm 0.04(stat) \pm 0.09(syst)MeV\,, m(\chi_{c2}) = 3556.10 \pm 0.06(stat) \pm 0.11(syst)MeV\,, where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. [...]
CERN-EP-2017-228; LHCB-PAPER-2017-036; arXiv:1709.04247; LHCB-PAPER-2017-036.- Geneva : CERN, 2017-11-28 - 9 p. - Published in : Phys. Rev. Lett. 119 (2017) 221801 Fulltext: PDF; Preprint: PDF; Related data file(s): ZIP; Supplementary information: ZIP;

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2017-09-14
12:21
Measurement of $CP$ violation in $B^0\rightarrow J/\psi K^0_\mathrm{S}$ and $B^0\rightarrow\psi(2S) K^0_\mathrm{S}$ decays / LHCb Collaboration
A measurement is presented of decay-time-dependent $CP$ violation in the decays $B^0\rightarrow J/\psi K^0_\mathrm{S}$ and $B^0\rightarrow\psi(2S) K^0_\mathrm{S}$, where the $J/\psi$ is reconstructed from two electrons and the $\psi(2S)$ from two muons. The analysis uses a sample of $pp$ collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 $\mathrm{fb}^{-1}$. [...]
LHCB-PAPER-2017-029; CERN-EP-2017-209; arXiv:1709.03944; LHCB-PAPER-2017-029.- Geneva : CERN, 2017-11-27 - 18 p. - Published in : JHEP 11 (2017) 170 Article from SCOAP3: PDF; Preprint: PDF; Related data file(s): ZIP;

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2017-09-12
11:56
First observation of forward $Z \rightarrow b \bar{b}$ production in $pp$ collisions at $\sqrt{s}=8$ TeV / LHCb Collaboration
The decay $Z \rightarrow b \bar{b}$ is reconstructed in $pp$ collision data, corresponding to 2 fb$^{-1}$ of integrated luminosity, collected by the LHCb experiment at a centre-of-mass energy of $\sqrt{s}=8$ TeV. The product of the $Z$ production cross-section and the $Z \rightarrow b \bar{b}$ branching fraction is measured for candidates in the fiducial region defined by two particle-level $b$-quark jets with pseudorapidities in the range $2.2 < \eta < 4.2$, with transverse momenta $p_{T}>20$ GeV and dijet invariant mass in the range $45 < m_{jj} < 165$ GeV. [...]
LHCB-PAPER-2017-024; CERN-EP-2017-211; LHCB-PAPER-2017-024-AND-CERN-EP-2017-211; arXiv:1709.03458; LHCB-PAPER-2017-024.- Geneva : CERN, 2018-01-10 - 10 p. - Published in : Phys. Lett. B 776 (2018) 430-439 Article from SCOAP3: PDF; Preprint: PDF; Related data file(s): ZIP;

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2017-09-08
16:35
Measurement of the shape of the $\Lambda_b^0\to\Lambda_c^+ \mu^- \overline{\nu}_{\mu}$ differential decay rate / LHCb Collaboration
A measurement of the shape of the differential decay rate and the associated Isgur-Wise function for the decay $\Lambda_b^0\to\Lambda_c^+\mu^-\overline{\nu}$ is reported, using data corresponding to $3 fb^{-1}$ collected with the LHCb detector in proton-proton collisions. The $\Lambda_c^+\mu^-\overline{\nu}$(+ anything) final states are reconstructed through the detection of a muon and a $\Lambda_c^+$ baryon decaying into $pK^-\pi^+$, and the decays $\Lambda_b^0\to\Lambda_c^+\pi^+\pi^-\mu^-\overline{\nu}$ are used to determine contributions from $\Lambda_b^0\to \Lambda_c^{\star+}\mu ^-\bar{\nu}$ decays. [...]
CERN-EP-2017-164; LHCB-PAPER-2017-016; CERN-PH-EP-2017-164; arXiv:1709.01920.- Geneva : CERN, 2017-12-13 - 15 p. - Published in : Phys. Rev. D 96 (2017) 112005 Fulltext: PDF; Preprint: PDF; Related data file(s): ZIP;

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2017-09-08
10:15
Bose-Einstein correlations of same-sign charged pions in the forward region in $pp$ collisions at $\sqrt{s}$ = 7 TeV / LHCb Collaboration
Bose-Einstein correlations of same-sign charged pions, produced in proton-proton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. [...]
CERN-EP-2017-203; LHCB-PAPER-2017-025; arXiv:1709.01769; LHCB-PAPER-2017-025.- Geneva : CERN, 2017-12-06 - Published in : JHEP 12 (2017) 025 Article from SCOAP3: PDF; Preprint: PDF; Related data file(s): ZIP;

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