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Measurement of the branching fractions of the decays $D^+\rightarrow K^-K ^+K^+$, $D^+\rightarrow π^-π^+K^+$ and $D^+_s\rightarrow π^-K^+K^+$
Authors:
LHCb collaboration,
R. Aaij,
C. Abellán Beteta,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (821 additional authors not shown)
Abstract:
The branching fractions of the doubly Cabibbo-suppressed decays $D^+\rightarrow K^-K^+K^+$, $D^+\rightarrow π^-π^+K^+$ and $D^+_s\rightarrowπ^-K^+K^+$ are measured using the decays $D^+\rightarrow K^-π^+π^+$ and $D^+_s\rightarrow K^-K^+π^+$ as normalisation channels. The measurements are performed using proton-proton collision data collected with the LHCb detector at a centre-of-mass energy of 8 T…
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The branching fractions of the doubly Cabibbo-suppressed decays $D^+\rightarrow K^-K^+K^+$, $D^+\rightarrow π^-π^+K^+$ and $D^+_s\rightarrowπ^-K^+K^+$ are measured using the decays $D^+\rightarrow K^-π^+π^+$ and $D^+_s\rightarrow K^-K^+π^+$ as normalisation channels. The measurements are performed using proton-proton collision data collected with the LHCb detector at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 2.0 fb$^{-1}$. The results are
\begin{align}
\frac {\mathcal{B}(D^+\rightarrow K^-K^+K^+)} {\mathcal{B}(D^+\rightarrow K^-π^+π^+)}& = (6.541 \pm 0.025 \pm 0.042) \times 10^{-4},\nonumber
\frac {\mathcal{B}(D^+\rightarrow π^-π^+K^+)} {\mathcal{B}(D^+\rightarrow K^-π^+π^+)}& = (5.231 \pm 0.009 \pm 0.023) \times 10^{-3}, \nonumber
\frac {\mathcal{B}(D^+_s\rightarrowπ^-K^+K^+)} {\mathcal{B}(D^+_s\rightarrow K^-K^+π^+)}& = (2.372 \pm 0.024 \pm 0.025) \times 10^{-3},\nonumber
\end{align} where the uncertainties are statistical and systematic, respectively. These are the most precise measurements up to date.
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Submitted 5 April, 2019; v1 submitted 7 October, 2018;
originally announced October 2018.
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Observation of two resonances in the $Λ_b^0 π^\pm$ systems and precise measurement of $Σ_b^\pm$ and $Σ_b^{*\pm}$ properties
Authors:
LHCb collaboration,
R. Aaij,
C. Abellán Beteta,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (817 additional authors not shown)
Abstract:
The first observation of two structures consistent with resonances in the final states $Λ_b^0 π^-$ and $Λ_b^0 π^+$ is reported using samples of $pp$ collision data collected by the LHCb experiment at $\sqrt{s} = 7$ and $8$ TeV, corresponding to an integrated luminosity of 3 $\mathrm{fb}^{-1}$. The ground states $Σ_b^\pm$ and $Σ_b^{*\pm}$ are also confirmed and their masses and widths are precisely…
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The first observation of two structures consistent with resonances in the final states $Λ_b^0 π^-$ and $Λ_b^0 π^+$ is reported using samples of $pp$ collision data collected by the LHCb experiment at $\sqrt{s} = 7$ and $8$ TeV, corresponding to an integrated luminosity of 3 $\mathrm{fb}^{-1}$. The ground states $Σ_b^\pm$ and $Σ_b^{*\pm}$ are also confirmed and their masses and widths are precisely measured.
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Submitted 11 October, 2018; v1 submitted 20 September, 2018;
originally announced September 2018.
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Evidence for an $η_c(1S) π^-$ resonance in $B^0 \to η_c(1S) K^+π^-$ decays
Authors:
LHCb collaboration,
R. Aaij,
C. Abellán Beteta,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (822 additional authors not shown)
Abstract:
A Dalitz plot analysis of $B^0 \to η_c(1S) K^+π^-$ decays is performed using data samples of $pp$ collisions collected with the LHCb detector at centre-of-mass energies of $\sqrt{s}=7,~8$ and $13$ TeV, corresponding to a total integrated luminosity of $4.7~\text{fb}^{-1}$. A satisfactory description of the data is obtained when including a contribution representing an exotic $η_c(1S) π^-$ resonant…
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A Dalitz plot analysis of $B^0 \to η_c(1S) K^+π^-$ decays is performed using data samples of $pp$ collisions collected with the LHCb detector at centre-of-mass energies of $\sqrt{s}=7,~8$ and $13$ TeV, corresponding to a total integrated luminosity of $4.7~\text{fb}^{-1}$. A satisfactory description of the data is obtained when including a contribution representing an exotic $η_c(1S) π^-$ resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are $4096 \pm 20~^{+18}_{-22}$ MeV and $152 \pm 58~^{+60}_{-35}$ MeV, respectively. The spin-parity assignments $J^P=0^+$ and $J^{P}=1^-$ are both consistent with the data. In addition, the first measurement of the $B^0 \to η_c(1S) K^+π^-$ branching fraction is performed and gives $\displaystyle \mathcal{B}(B^0 \to η_c(1S) K^+π^-) = (5.73 \pm 0.24 \pm 0.13 \pm 0.66) \times 10^{-4}$, where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions.
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Submitted 18 December, 2018; v1 submitted 19 September, 2018;
originally announced September 2018.
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Prompt $Λ^+_c$ production in $p\mathrm{Pb}$ collisions at $\sqrt{s_{NN}} = 5.02$ TeV
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (812 additional authors not shown)
Abstract:
The production of $Λ^+_c$ baryons produced directly at the interacting point is studied in proton-lead collisions collected with the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of $1.58\mathrm{nb}^{-1}$ recorded at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{NN}}=5.02$ TeV. Measurements of the differential cross-section and the forward-backward produc…
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The production of $Λ^+_c$ baryons produced directly at the interacting point is studied in proton-lead collisions collected with the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of $1.58\mathrm{nb}^{-1}$ recorded at a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{NN}}=5.02$ TeV. Measurements of the differential cross-section and the forward-backward production ratio are reported for $Λ^+_c$ baryons with transverse momenta in the range $2<p_{T}<10$GeV/$c$ and rapidities in the ranges $1.5<y^*<4.0$ and $-4.5<y^*<-2.5$ in the nucleon-nucleon centre-of-mass system. The ratio of cross-sections of $Λ^+_c$ baryons and $D^0$ mesons is also reported. The results are compared with next-to-leading order calculations that use nuclear parton distribution functions.
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Submitted 7 March, 2019; v1 submitted 5 September, 2018;
originally announced September 2018.
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Physics case for an LHCb Upgrade II - Opportunities in flavour physics, and beyond, in the HL-LHC era
Authors:
LHCb collaboration,
I. Bediaga,
M. Cruz Torres,
J. M. De Miranda,
A. Gomes,
A. Massafferri,
J. Molina Rodriguez,
A. C. dos Reis,
l. Soares Lavra,
R. Tourinho Jadallah Aoude,
S. Amato,
K. Carvalho Akiba,
F. Da Cunha Marinho,
L. De Paula,
F. Ferreira Rodrigues,
M. Gandelman,
A. Hicheur,
J. H. Lopes,
I. Nasteva,
J. M. Otalora Goicochea,
E. Polycarpo,
C. Potterat,
M. S. Rangel,
L. Silva de Oliveira,
B. Souza De Paula
, et al. (809 additional authors not shown)
Abstract:
The LHCb Upgrade II will fully exploit the flavour-physics opportunities of the HL-LHC, and study additional physics topics that take advantage of the forward acceptance of the LHCb spectrometer. The LHCb Upgrade I will begin operation in 2020. Consolidation will occur, and modest enhancements of the Upgrade I detector will be installed, in Long Shutdown 3 of the LHC (2025) and these are discussed…
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The LHCb Upgrade II will fully exploit the flavour-physics opportunities of the HL-LHC, and study additional physics topics that take advantage of the forward acceptance of the LHCb spectrometer. The LHCb Upgrade I will begin operation in 2020. Consolidation will occur, and modest enhancements of the Upgrade I detector will be installed, in Long Shutdown 3 of the LHC (2025) and these are discussed here. The main Upgrade II detector will be installed in long shutdown 4 of the LHC (2030) and will build on the strengths of the current LHCb experiment and the Upgrade I. It will operate at a luminosity up to $ 2 \times 10^{34} \rm cm^{-2}s^{-1}$, ten times that of the Upgrade I detector. New detector components will improve the intrinsic performance of the experiment in certain key areas. An Expression Of Interest proposing Upgrade II was submitted in February 2017. The physics case for the Upgrade II is presented here in more depth. $CP$-violating phases will be measured with precisions unattainable at any other envisaged facility. The experiment will probe $b\to s \ell^+\ell^-$ and $b\to d \ell^+\ell^-$ transitions in both muon and electron decays in modes not accessible at Upgrade I. Minimal flavour violation will be tested with a precision measurement of the ratio of $B(B^0\toμ^+μ^-)/B(B_s^0\to μ^+μ^-)$. Probing charm $CP$ violation at the $10^{-5}$ level may result in its long sought discovery. Major advances in hadron spectroscopy will be possible, which will be powerful probes of low energy QCD. Upgrade II potentially will have the highest sensitivity of all the LHC experiments on the Higgs to charm-quark couplings. Generically, the new physics mass scale probed, for fixed couplings, will almost double compared with the pre-HL-LHC era; this extended reach for flavour physics is similar to that which would be achieved by the HE-LHC proposal for the energy frontier.
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Submitted 5 April, 2019; v1 submitted 27 August, 2018;
originally announced August 2018.
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Search for lepton-flavour-violating decays of Higgs-like bosons
Authors:
LHCb collaboration,
R. Aaij,
C. Abellán Beteta,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (815 additional authors not shown)
Abstract:
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/$c^2$ decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV, collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb$^{-1}$. The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limi…
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A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/$c^2$ decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV, collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb$^{-1}$. The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/$c^2$ to 4 pb for a mass of 195 GeV/$c^2$.
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Submitted 20 December, 2018; v1 submitted 21 August, 2018;
originally announced August 2018.
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Measurement of antiproton production in ${\rm p He}$ collisions at $\sqrt{s_{NN}}=110$ GeV
Authors:
LHCb collaboration,
R. Aaij,
C. Abellán Beteta,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (819 additional authors not shown)
Abstract:
The cross-section for prompt antiproton production in collisions of protons with an energy of $6.5$ TeV incident on helium nuclei at rest is measured with the LHCb experiment from a data set corresponding to an integrated luminosity of $0.5\,nb^{-1}$. The target is provided by injecting helium gas into the LHC beam line at the LHCb interaction point. The reported results, covering antiproton momen…
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The cross-section for prompt antiproton production in collisions of protons with an energy of $6.5$ TeV incident on helium nuclei at rest is measured with the LHCb experiment from a data set corresponding to an integrated luminosity of $0.5\,nb^{-1}$. The target is provided by injecting helium gas into the LHC beam line at the LHCb interaction point. The reported results, covering antiproton momenta between $12$ and $110\,\mathrm{GeV/}c$, represent the first direct determination of the antiproton production cross-section in ${\rm p He}$ collisions, and impact the interpretation of recent results on antiproton cosmic rays from space-borne experiments.
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Submitted 30 November, 2018; v1 submitted 18 August, 2018;
originally announced August 2018.
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Angular moments of the decay $Λ_b^0 \rightarrow Λμ^{+} μ^{-}$ at low hadronic recoil
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (815 additional authors not shown)
Abstract:
An analysis of the angular distribution of the decay $Λ_b^0 \rightarrow Λμ^{+} μ^{-}$ is presented, using data collected with the LHCb detector between 2011 and 2016 and corresponding to an integrated luminosity of approximately $5\,fb^{-1}$. Angular observables are determined using a moment analysis of the angular distribution at low hadronic recoil, corresponding to the dimuon invariant mass squ…
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An analysis of the angular distribution of the decay $Λ_b^0 \rightarrow Λμ^{+} μ^{-}$ is presented, using data collected with the LHCb detector between 2011 and 2016 and corresponding to an integrated luminosity of approximately $5\,fb^{-1}$. Angular observables are determined using a moment analysis of the angular distribution at low hadronic recoil, corresponding to the dimuon invariant mass squared range $15 < q^{2} < 20\, GeV^2/c^4$. The full basis of observables is measured for the first time. The lepton-side, hadron-side and combined forward-backward asymmetries of the decay are determined to be \begin{align} A_{FB}^{l} & = -0.39 \pm 0.04\,\rm{stat} \pm 0.01\, \rm{syst}, \nonumber\\ A_{FB}^{h} & = -0.30 \pm 0.05\,\rm{stat} \pm 0.02\, \rm{syst}, \nonumber\\ A_{FB}^{lh} & = +0.25 \pm 0.04\,\rm{stat} \pm 0.01\, \rm{syst}. \nonumber \end{align} The measurements are consistent with Standard Model predictions.
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Submitted 12 October, 2018; v1 submitted 1 August, 2018;
originally announced August 2018.
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Measurement of the relative $B^{-} \!\rightarrow D^{0} / D^{*0} / D^{**0} μ^{-} \overlineν_μ$ branching fractions using $B^{-}$ mesons from $\overline{B}{}_{s2}^{*0}$ decays
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (814 additional authors not shown)
Abstract:
The decay of the narrow resonance $\overline{B}{}_{s2}^{*0}\!\rightarrow B^- K^+$ can be used to determine the $B^-$ momentum in partially reconstructed decays without any assumptions on the decay products of the $B^-$ meson. This technique is employed for the first time to distinguish contributions from $D^0$, $D^{*0}$, and higher-mass charmed states ($D^{**0}$) in semileptonic $B^-$ decays by us…
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The decay of the narrow resonance $\overline{B}{}_{s2}^{*0}\!\rightarrow B^- K^+$ can be used to determine the $B^-$ momentum in partially reconstructed decays without any assumptions on the decay products of the $B^-$ meson. This technique is employed for the first time to distinguish contributions from $D^0$, $D^{*0}$, and higher-mass charmed states ($D^{**0}$) in semileptonic $B^-$ decays by using the missing-mass distribution. The measurement is performed using a data sample corresponding to an integrated luminosity of 3.0 fb${}^{-1}$ collected with the LHCb detector in $pp$ collisions at center-of-mass energies of 7 and 8 TeV. The resulting branching fractions relative to the inclusive $B^- \!\rightarrow D^0 X μ^- \overlineν_μ$ are $f_{D^0} = \mathcal{B}( B^- \rightarrow D^0μ^-\overlineν_μ)/\mathcal{B}( B^- \rightarrow D^0 X μ^- \overlineν_μ) = 0.25 \pm 0.06$, $f_{D^{**0}} = \mathcal{B}( B^- \rightarrow ( D^{**0} \rightarrow D^0 X)μ^-\overlineν_μ)/\mathcal{B}( B^- \rightarrow D^0 X μ^- \overlineν_μ) = 0.21 \pm 0.07$, with $f_{D^{*0}} = 1 - f_{D^0} - f_{D^{**0}}$ making up the remainder.
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Submitted 3 June, 2019; v1 submitted 27 July, 2018;
originally announced July 2018.
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Search for $C\!P$ violation in $Λ^0_b \to p K^-$ and $Λ^0_b \to p π^-$ decays
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (814 additional authors not shown)
Abstract:
A search for $C\!P$ violation in $Λ^0_b \to p K^-$ and $Λ^0_b \to p π^-$ decays is presented using a sample of $pp$ collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $C\!P$-violating asymmetries are measured to be $A_{\mathrm{CP}}^{pK^-} = -0.020 \pm 0.013\pm 0.019$ and $A_{\mathrm{CP}}^{pπ^-} = -0.035 \pm 0.017 \pm 0.020 $, and their d…
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A search for $C\!P$ violation in $Λ^0_b \to p K^-$ and $Λ^0_b \to p π^-$ decays is presented using a sample of $pp$ collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $C\!P$-violating asymmetries are measured to be $A_{\mathrm{CP}}^{pK^-} = -0.020 \pm 0.013\pm 0.019$ and $A_{\mathrm{CP}}^{pπ^-} = -0.035 \pm 0.017 \pm 0.020 $, and their difference $A_{\mathrm{CP}}^{pK^-}-A_{\mathrm{CP}}^{pπ^-} = 0.014 \pm 0.022 \pm 0.010$, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date.
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Submitted 9 November, 2018; v1 submitted 17 July, 2018;
originally announced July 2018.
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Measurement of the $Ω_c^0$ baryon lifetime
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (814 additional authors not shown)
Abstract:
We report a measurement of the lifetime of the $Ω_c^0$ baryon using proton-proton collision data at center-of-mass energies of 7 and 8~TeV, corresponding to an integrated luminosity of 3.0 fb$^{-1}$ collected by the LHCb experiment. The sample consists of about 1000 $Ω_b^-\toΩ_c^0μ^-\barν_μ X$ signal decays, where the $Ω_c^0$ baryon is detected in the $pK^-K^-π^+$ final state and $X$ represents po…
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We report a measurement of the lifetime of the $Ω_c^0$ baryon using proton-proton collision data at center-of-mass energies of 7 and 8~TeV, corresponding to an integrated luminosity of 3.0 fb$^{-1}$ collected by the LHCb experiment. The sample consists of about 1000 $Ω_b^-\toΩ_c^0μ^-\barν_μ X$ signal decays, where the $Ω_c^0$ baryon is detected in the $pK^-K^-π^+$ final state and $X$ represents possible additional undetected particles in the decay. The $Ω_c^0$ lifetime is measured to be $τ_{Ω_c^0} = 268\pm24\pm10\pm2$ fs, where the uncertainties are statistical, systematic, and from the uncertainty in the $D^+$ lifetime, respectively. This value is nearly four times larger than, and inconsistent with, the current world-average value.
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Submitted 31 August, 2018; v1 submitted 5 July, 2018;
originally announced July 2018.
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First observation of the doubly charmed baryon decay $Ξ_{cc}^{++}\rightarrow Ξ_{c}^{+}π^{+}$
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (814 additional authors not shown)
Abstract:
The doubly charmed baryon decay $Ξ_{cc}^{++} \rightarrow Ξ_{c}^{+} π^{+}$ is observed for the first time, with a statistical significance of $5.9σ$, confirming a recent observation of the baryon in the $Λ_c^{+} K^{-} π^{+} π^{+}$ final state. The data sample used corresponds to an integrated luminosity of $1.7\,\mathrm{fb}^{-1}$, collected by the LHCb experiment in $pp$ collisions at a center-of-m…
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The doubly charmed baryon decay $Ξ_{cc}^{++} \rightarrow Ξ_{c}^{+} π^{+}$ is observed for the first time, with a statistical significance of $5.9σ$, confirming a recent observation of the baryon in the $Λ_c^{+} K^{-} π^{+} π^{+}$ final state. The data sample used corresponds to an integrated luminosity of $1.7\,\mathrm{fb}^{-1}$, collected by the LHCb experiment in $pp$ collisions at a center-of-mass energy of $13\mathrm{\,Te\kern -0.1em V}$. The $Ξ_{cc}^{++}$ mass is measured to be
\begin{equation}\nonumber
3620.6\pm 1.5~(\text{stat})\pm 0.4~(\text{syst}) \pm 0.3~(Ξ_{c}^{+})~\text{MeV}/\it{c}^{2},
\end{equation}
and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be
\begin{equation}\nonumber
\frac{\mathcal{B} (Ξ_{cc}^{++} \rightarrow Ξ_{c}^{+} π^{+}) \times \mathcal{B}(Ξ_{c}^{+} \rightarrow pK^{-}π^{+})}
{\mathcal{B} (Ξ_{cc}^{++} \rightarrow Λ_c^{+} K^{-} π^{+} π^{+}) \times \mathcal{B}(Λ_c^{+} \rightarrow pK^{-}π^{+})}
= 0.035\pm 0.009~(\text{stat}) \pm 0.003~(\text{syst}).
\end{equation}
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Submitted 18 October, 2018; v1 submitted 5 July, 2018;
originally announced July 2018.
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Observation of $B_s^0 \to \overline{D}^{*0} φ$ and search for $B^0 \to \overline{D}^0 φ$ decays
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (787 additional authors not shown)
Abstract:
The first observation of the $B_s^0 \to \overline{D}^{*0} φ$ decay is reported, with a significance of more than seven standard deviations, from an analysis of $pp$ collision data corresponding to an integrated luminosity of 3 fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of $7$ and $8$ TeV. The branching fraction is measured relative to that of the topologically similar d…
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The first observation of the $B_s^0 \to \overline{D}^{*0} φ$ decay is reported, with a significance of more than seven standard deviations, from an analysis of $pp$ collision data corresponding to an integrated luminosity of 3 fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of $7$ and $8$ TeV. The branching fraction is measured relative to that of the topologically similar decay $B^0 \to \overline{D}^0 π^+π^-$ and is found to be $\mathcal{B}(B_s^0 \to \overline{D}^{*0} φ) = (3.7 \pm 0.5 \pm 0.3 \pm 0.2) \times 10^{-5}$, where the first uncertainty is statistical, the second systematic, and the third from the branching fraction of the $B^0 \to \overline{D}^0 π^+π^-$ decay. The fraction of longitudinal polarisation in this decay is measured to be ${f_{\rm L} =(73 \pm 15 \pm 3)\%}$. The most precise determination of the branching fraction for the $B_s^0 \to \overline{D}^{0} φ$ decay is also obtained, $\mathcal{B}(B_s^0 \to \overline{D}^{0} φ) = (3.0 \pm 0.3 \pm 0.2 \pm 0.2) \times 10^{-5}$. An upper limit, $\mathcal{B}(B^0 \to \overline{D}^{0} φ) < 2.0 \ (2.2) \times 10^{-6}$ at $90\%$ (95\%) confidence level is set. A constraint on the $ω-φ$ mixing angle $δ$ is set at $|δ| < 5.2^\circ~ (5.5^\circ)$ at $90\%$ ($95\%$) confidence level.
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Submitted 8 November, 2018; v1 submitted 5 July, 2018;
originally announced July 2018.
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Observation of the decay $B_s^0 \to \overline{D}^0 K^+ K^-$
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (788 additional authors not shown)
Abstract:
The first observation of the $B_s^0 \to \overline{D}^0 K^+ K^-$ decay is reported, together with the most precise branching fraction measurement of the mode $B^0 \to \overline{D}^0 K^+ K^-$. The results are obtained from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3.0~\textrm{fb}^{-1}$. The data were collected with the LHCb detector at centre-of-mass energies o…
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The first observation of the $B_s^0 \to \overline{D}^0 K^+ K^-$ decay is reported, together with the most precise branching fraction measurement of the mode $B^0 \to \overline{D}^0 K^+ K^-$. The results are obtained from an analysis of $pp$ collision data corresponding to an integrated luminosity of $3.0~\textrm{fb}^{-1}$. The data were collected with the LHCb detector at centre-of-mass energies of $7$ and $8$ TeV. The branching fraction of the $B^0 \to \overline{D}^0 K^+ K^-$ decay is measured relative to that of the decay $B^0 \to \overline{D}^0 π^+ π^-$ to be $$\frac{\mathcal{B}(B^0 \to \overline{D}^0 K^+ K^-)}{\mathcal{B}(B^0 \to \overline{D}^0 π^+ π^-)} = (6.9 \pm 0.4 \pm 0.3)\%,$$ where the first uncertainty is statistical and the second is systematic. The measured branching fraction of the $B_s^0 \to \overline{D}^0 K^+ K^-$ decay mode relative to that of the corresponding $B^0$ decay is $$\frac{\mathcal{B}(B_s^0 \to \overline{D}^0 K^+ K^-)}{\mathcal{B}(B^0 \to \overline{D}^0 K^+ K^-)} = (93.0 \pm 8.9 \pm 6.9)\%.$$ Using the known branching fraction of ${B^0 \to \overline{D}^0 π^+ π^-}$, the values of ${{\mathcal B}(B^0 \to \overline{D}^0 K^+ K^- )=(6.1 \pm 0.4 \pm 0.3 \pm 0.3) \times 10^{-5}}$, and ${{\cal B}(B_s^0 \to \overline{D}^0 K^+ K^-)=}$ $(5.7 \pm 0.5 \pm 0.4 \pm 0.5) \times 10^{-5}$ are obtained, where the third uncertainties arise from the branching fraction of the decay modes ${B^0 \to \overline{D}^0 π^+ π^-}$ and $B^0 \to \overline{D}^0 K^+ K^-$, respectively.
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Submitted 8 November, 2018; v1 submitted 5 July, 2018;
originally announced July 2018.
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Measurement of angular and CP asymmetries in $D^0\toπ^+π^-μ^+μ^-$ and $D^0\to K^+K^-μ^+μ^-$ decays
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (812 additional authors not shown)
Abstract:
The first measurements of the forward-backward asymmetry of the dimuon pair ($A_{FB}$), the triple-product asymmetry ($A_{2φ}$), and the charge-parity-conjugation asymmetry ($A_{CP}$), in $D^0\toπ^+π^-μ^+μ^-$ and $D^0\to K^+K^-μ^+μ^-$ decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integ…
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The first measurements of the forward-backward asymmetry of the dimuon pair ($A_{FB}$), the triple-product asymmetry ($A_{2φ}$), and the charge-parity-conjugation asymmetry ($A_{CP}$), in $D^0\toπ^+π^-μ^+μ^-$ and $D^0\to K^+K^-μ^+μ^-$ decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5 fb$^{-1}$. The asymmetries are measured to be \begin{align*} A_{FB}(D^0\toπ^+π^-μ^+μ^-) &= (\phantom{-}3.3\pm3.7\pm0.6)\%,\\ A_{2φ}(D^0\toπ^+π^-μ^+μ^-)&= (-0.6\pm3.7\pm0.6)\%,\\ A_{CP}(D^0\toπ^+π^-μ^+μ^-) &= (\phantom{-}4.9\pm3.8\pm0.7)\%,\\ A_{FB}(D^0\to K^+K^-μ^+μ^-) &= (0\pm11\pm2)\%,\\ A_{2φ}(D^0\to K^+K^-μ^+μ^-)&= (9\pm11\pm1)\%,\\ A_{CP}(D^0\to K^+K^-μ^+μ^-) &= (0\pm11\pm2)\%, \end{align*} where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the Standard Model predictions.
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Submitted 31 August, 2018; v1 submitted 28 June, 2018;
originally announced June 2018.
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Observation of the decay $\overline{B_s^0} \rightarrow χ_{c2} K^+ K^- $ in the $\varphi$ mass region
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (808 additional authors not shown)
Abstract:
The $\overline{B_s^0} \rightarrow χ_{c2} K^+ K^- $ decay mode is observed and its branching fraction relative to the corresponding $χ_{c1}$ decay mode, in a $\pm 15 \textrm{MeV}/c^2$ window around the $φ$ mass, is found to be $\frac{\mathcal{B}(\overline{B_s^0} \rightarrow χ_{c2} K^+ K^-) }{ \mathcal{B}(\overline{B_s^0} \rightarrow χ_{c1} K^+ K^-)} = (17.1 \pm 3.1 \pm 0.4 \pm 0.9)\%,$ where the fi…
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The $\overline{B_s^0} \rightarrow χ_{c2} K^+ K^- $ decay mode is observed and its branching fraction relative to the corresponding $χ_{c1}$ decay mode, in a $\pm 15 \textrm{MeV}/c^2$ window around the $φ$ mass, is found to be $\frac{\mathcal{B}(\overline{B_s^0} \rightarrow χ_{c2} K^+ K^-) }{ \mathcal{B}(\overline{B_s^0} \rightarrow χ_{c1} K^+ K^-)} = (17.1 \pm 3.1 \pm 0.4 \pm 0.9)\%,$ where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the branching fractions of radiative $χ_c$ decays. The decay mode $\overline{B_s^0} \rightarrow χ_{c1} K^+ K^- $ allows the $ B_s^0$ mass to be measured as $m(B_s^0) = 5366.83 \pm 0.25 \pm 0.27 \, \textrm{MeV}/c^2,$ where the first uncertainty is statistical and the second systematic. A combination of this result with other LHCb determinations of the $B_s^0$ mass is made.
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Submitted 11 September, 2018; v1 submitted 27 June, 2018;
originally announced June 2018.
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Search for beautiful tetraquarks in the $Υ(1S)μμ$ invariant-mass spectrum
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (816 additional authors not shown)
Abstract:
The $Υ(1S)μ^+μ^-$ invariant-mass distribution is investigated for a possible exotic meson state composed of two $b$ quarks and two $\overline{b}$ quarks, $X_{b\overline{b}b\overline{b}}$. The analysis is based on a data sample of $pp$ collisions recorded with the LHCb detector at centre-of-mass energies $\sqrt{s} =$ 7, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb$^{-1}$. No si…
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The $Υ(1S)μ^+μ^-$ invariant-mass distribution is investigated for a possible exotic meson state composed of two $b$ quarks and two $\overline{b}$ quarks, $X_{b\overline{b}b\overline{b}}$. The analysis is based on a data sample of $pp$ collisions recorded with the LHCb detector at centre-of-mass energies $\sqrt{s} =$ 7, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb$^{-1}$. No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the $X_{b\overline{b}b\overline{b}}$ state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range $[2.0,5.0]$, and the $X_{b\overline{b}b\overline{b}}$ state has rapidity in the range $[2.0,4.5]$ and transverse momentum less than 15 GeV/$c$.
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Submitted 7 November, 2018; v1 submitted 25 June, 2018;
originally announced June 2018.
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Observation of the decay $Λ^0_b\rightarrowψ(2S)pπ^-$
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (814 additional authors not shown)
Abstract:
The Cabibbo-suppressed decay $Λ^0_b\rightarrowψ(2S)pπ^-$ is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9fb$^{-1}$ of integrated luminosity at centre-of-mass energies of 7, 8 and 13TeV, respectively. The $ψ(2S)$ mesons are reconstructed in the $μ^+μ^-$ final state. The~branching fraction with respect t…
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The Cabibbo-suppressed decay $Λ^0_b\rightarrowψ(2S)pπ^-$ is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9fb$^{-1}$ of integrated luminosity at centre-of-mass energies of 7, 8 and 13TeV, respectively. The $ψ(2S)$ mesons are reconstructed in the $μ^+μ^-$ final state. The~branching fraction with respect to that of the $Λ^0_b\rightarrowψ(2S)pK^-$ decay mode is measured to be $$\frac{\mathcal{B}\left(Λ^0_b\rightarrowψ(2S)pπ^- \right)} {\mathcal{B}\left(Λ^0_b\rightarrowψ(2S)pK^-\right)}=\left(11.4 \pm 1.3 \pm 0.2\right)\!\%\,,$$ where the first uncertainty is statistical and the second is systematic. The $ψ(2S)p$ and $ψ(2S)π^-$ mass spectra are investigated and no evidence for exotic resonances is found.
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Submitted 25 September, 2018; v1 submitted 21 June, 2018;
originally announced June 2018.
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Measurement of $Z\rightarrowτ^+τ^-$ production in proton-proton collisions at $\sqrt{s} = 8$ TeV
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (801 additional authors not shown)
Abstract:
A measurement of $Z\rightarrowτ^+τ^-$ production cross-section is presented using data, corresponding to an integrated luminosity of 2 fb$^{-1}$, from $pp$ collisions at $\sqrt{s}=8$ TeV collected by the LHCb experiment. The $τ^+τ^-$ candidates are reconstructed in final states with the first tau lepton decaying leptonically, and the second decaying either leptonically or to one or three charged h…
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A measurement of $Z\rightarrowτ^+τ^-$ production cross-section is presented using data, corresponding to an integrated luminosity of 2 fb$^{-1}$, from $pp$ collisions at $\sqrt{s}=8$ TeV collected by the LHCb experiment. The $τ^+τ^-$ candidates are reconstructed in final states with the first tau lepton decaying leptonically, and the second decaying either leptonically or to one or three charged hadrons. The production cross-section is measured for $Z$ bosons with invariant mass between 60 and 120 GeV/$c^2$, which decay to tau leptons with transverse momenta greater than 20 GeV/$c$ and pseudorapidities between 2.0 and 4.5. The cross-section is determined to be $σ_{pp\rightarrow{}Z\rightarrow{}τ^+τ^-} = 95.8 \pm 2.1 \pm 4.6 \pm 0.2 \pm 1.1 \mathrm{pb}$, where the first uncertainty is statistical, the second is systematic, the third is due to the LHC beam energy uncertainty, and the fourth to the integrated luminosity uncertainty. This result is compatible with NNLO Standard model predictions. The ratio of the cross-sections for $Z\rightarrowτ^+τ^-$ to $Z\rightarrowμ^+μ^-$ ($Z\rightarrow{}e^+e^-$), determined to be $1.01 \pm 0.05$ ($1.02 \pm 0.06$), is consistent with the lepton-universality hypothesis in $Z$ decays.
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Submitted 8 October, 2018; v1 submitted 13 June, 2018;
originally announced June 2018.
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Central exclusive production of $J/ψ$ and $ψ(2S)$ mesons in $pp$ collisions at $\sqrt{s}=13~$TeV
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (788 additional authors not shown)
Abstract:
Measurements are reported of the central exclusive production of \jpsi and \psitwos mesons in $pp$ collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons ar…
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Measurements are reported of the central exclusive production of \jpsi and \psitwos mesons in $pp$ collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range $2.0<η<4.5$, are measured to be $$
\begin{array}{rcl} σ_{J/ψ\rightarrowμ^+μ^-}&=&435 \pm 18 \pm 17 \pm 16 {\rm \ pb},\\ σ_{ψ(2S)\rightarrowμ^+μ^-}&=&11.1 \pm 1.1 \pm 0.3 \pm 0.4 {\rm \ pb}.\\ \end{array} $$ The first uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross-sections are also measured differentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross-sections are derived and compared to previous experiments, and a deviation from a pure power-law extrapolation of lower energy data is observed.
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Submitted 30 October, 2018; v1 submitted 11 June, 2018;
originally announced June 2018.
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Measurement of the lifetime of the doubly charmed baryon $Ξ_{cc}^{++}$
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (812 additional authors not shown)
Abstract:
The first measurement of the lifetime of the doubly charmed baryon $Ξ_{cc}^{++}$ is presented, with the signal reconstructed in the final state $Λ_c^+ K^- π^+ π^+$. The data sample used corresponds to an integrated luminosity of $1.7\,\mathrm{fb}^{-1}$, collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of $13\mathrm{\,Te\kern -0.1em V}$. The $Ξ_{cc}^{++}$ life…
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The first measurement of the lifetime of the doubly charmed baryon $Ξ_{cc}^{++}$ is presented, with the signal reconstructed in the final state $Λ_c^+ K^- π^+ π^+$. The data sample used corresponds to an integrated luminosity of $1.7\,\mathrm{fb}^{-1}$, collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of $13\mathrm{\,Te\kern -0.1em V}$. The $Ξ_{cc}^{++}$ lifetime is measured to be $0.256\,^{+0.024}_{-0.022}{\,\rm (stat)\,} \pm 0.014 {\,\rm(syst)}\mathrm{\,ps}$.
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Submitted 31 July, 2018; v1 submitted 7 June, 2018;
originally announced June 2018.
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Measurement of the time-integrated $CP$ asymmetry in $D^0 \rightarrow K^0_S K^0_S$ decays
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (789 additional authors not shown)
Abstract:
A measurement of the time-integrated $CP$ asymmetry in $D^0\rightarrow K^0_S K^0_S$ decays is reported. The data correspond to an integrated luminosity of about $2$ fb$^{-1}$ collected in 2015-2016 by the LHCb collaboration in $pp$ collisions at a centre-of-mass energy of $13$ TeV. The $D^0$ candidate is required to originate from a $D^{\ast +} \rightarrow D^0 π^+$ decay, allowing the determinatio…
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A measurement of the time-integrated $CP$ asymmetry in $D^0\rightarrow K^0_S K^0_S$ decays is reported. The data correspond to an integrated luminosity of about $2$ fb$^{-1}$ collected in 2015-2016 by the LHCb collaboration in $pp$ collisions at a centre-of-mass energy of $13$ TeV. The $D^0$ candidate is required to originate from a $D^{\ast +} \rightarrow D^0 π^+$ decay, allowing the determination of the flavour of the $D^0$ meson using the pion charge. The $D^0 \rightarrow K^{+}K^{-}$ decay, which has a well measured $CP$ asymmetry, is used as a calibration channel. The $CP$ asymmetry for $D^0\rightarrow K^0_S K^0_S$ is measured to be \begin{equation*} \mathcal{A}^{CP}(D^0\rightarrow K^0_S K^0_S) = (4.3\pm 3.4\pm 1.0)\%, \end{equation*} where the first uncertainty is statistical and the second is systematic. This result is combined with the previous LHCb measurement at lower centre-of-mass energies to obtain \begin{equation*} \mathcal{A}^{CP}(D^0\rightarrow K^0_S K^0_S) = (2.3\pm 2.8\pm 0.9)\%. \end{equation*}
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Submitted 20 November, 2018; v1 submitted 5 June, 2018;
originally announced June 2018.
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Measurement of the CKM angle $γ$ using $B^\pm\to DK^\pm$ with $D\to K_\text{S}^0π^+π^-$, $K_\text{S}^0K^+K^-$ decays
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby
, et al. (799 additional authors not shown)
Abstract:
A binned Dalitz plot analysis of $B^\pm \to D K^\pm$ decays, with $D\to K_\text{S}^0π^+π^-$ and $D\to K_\text{S}^0K^+K^-$, is used to perform a measurement of the CP-violating observables $x_{\pm}$ and $y_{\pm}$, which are sensitive to the Cabibbo-Kobayashi-Maskawa angle $γ$. The analysis is performed without assuming any $D$ decay model, through the use of information on the strong-phase variatio…
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A binned Dalitz plot analysis of $B^\pm \to D K^\pm$ decays, with $D\to K_\text{S}^0π^+π^-$ and $D\to K_\text{S}^0K^+K^-$, is used to perform a measurement of the CP-violating observables $x_{\pm}$ and $y_{\pm}$, which are sensitive to the Cabibbo-Kobayashi-Maskawa angle $γ$. The analysis is performed without assuming any $D$ decay model, through the use of information on the strong-phase variation over the Dalitz plot from the CLEO collaboration. Using a sample of proton-proton collision data collected with the LHCb experiment in 2015 and 2016, and corresponding to an integrated luminosity of 2.0$\,\text{fb}^{-1}$, the values of the CP violation parameters are found to be $x_- = ( 9.0 \pm 1.7 \pm 0.7 \pm 0.4) \times 10^{-2}$, $y_- = ( 2.1 \pm 2.2 \pm 0.5 \pm 1.1) \times 10^{-2}$, $x_+ = (- 7.7 \pm 1.9 \pm 0.7 \pm 0.4) \times 10^{-2}$, and $y_+ = (- 1.0 \pm 1.9 \pm 0.4 \pm 0.9) \times 10^{-2}$. The first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the strong-phase measurements. These values are used to obtain $γ= \left(87\,^{+11}_{-12}\right)^\circ$, $r_B = 0.086^{+ 0.013}_{-0.014}$, and $δ_B = (101 \pm 11)^\circ$, where $r_B$ is the ratio between the suppressed and favoured $B$-decay amplitudes and $δ_B$ is the corresponding strong-interaction phase difference. This measurement is combined with the result obtained using 2011 and 2012 data collected with the \lhcb experiment, to give $γ= \left(80\,^{+10}_{\,-9}\right)^\circ$, $r_B = 0.080 \pm 0.011$, and $δ_B = (110 \pm 10)^\circ$.
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Submitted 21 September, 2018; v1 submitted 4 June, 2018;
originally announced June 2018.
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Search for a dimuon resonance in the $Υ$ mass region
Authors:
LHCb collaboration,
R. Aaij,
B. Adeva,
M. Adinolfi,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby,
F. Archilli
, et al. (768 additional authors not shown)
Abstract:
A search is performed for a spin-0 boson, $φ$, produced in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, using prompt $φ\rightarrowμ^+μ^-$ decays and a data sample corresponding to an integrated luminosity of approximately 3.0 ${\rm fb}^{-1}$ collected with the LHCb detector. No evidence is found for a signal in the mass range from 5.5 to 15 GeV. Upper limits are placed on th…
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A search is performed for a spin-0 boson, $φ$, produced in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, using prompt $φ\rightarrowμ^+μ^-$ decays and a data sample corresponding to an integrated luminosity of approximately 3.0 ${\rm fb}^{-1}$ collected with the LHCb detector. No evidence is found for a signal in the mass range from 5.5 to 15 GeV. Upper limits are placed on the product of the production cross-section and the branching fraction into the dimuon final state. The limits are comparable to the best existing over most of the mass region considered and are the first to be set near the $Υ$ resonances.
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Submitted 27 September, 2018; v1 submitted 24 May, 2018;
originally announced May 2018.
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Observation of a new $Ξ_b^-$ resonance
Authors:
R. Aaij,
B. Adeva,
M. Adinolfi,
C. A. Aidala,
Z. Ajaltouni,
S. Akar,
P. Albicocco,
J. Albrecht,
F. Alessio,
M. Alexander,
A. Alfonso Albero,
S. Ali,
G. Alkhazov,
P. Alvarez Cartelle,
A. A. Alves Jr,
S. Amato,
S. Amerio,
Y. Amhis,
L. An,
L. Anderlini,
G. Andreassi,
M. Andreotti,
J. E. Andrews,
R. B. Appleby,
F. Archilli
, et al. (786 additional authors not shown)
Abstract:
From samples of $pp$ collision data collected by the LHCb experiment at $\sqrt{s}=7$, $8$ and $13$ TeV corresponding to integrated luminosities of 1.0, 2.0 and 1.5 fb$^{-1}$, respectively, a peak in both the $Λ_b^0K^-$ and $Ξ_b^0π^-$ invariant mass spectra is observed. In the quark model, radially and orbitally excited $Ξ_b^-$ resonances with quark content $bds$ are expected. Referring to this pea…
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From samples of $pp$ collision data collected by the LHCb experiment at $\sqrt{s}=7$, $8$ and $13$ TeV corresponding to integrated luminosities of 1.0, 2.0 and 1.5 fb$^{-1}$, respectively, a peak in both the $Λ_b^0K^-$ and $Ξ_b^0π^-$ invariant mass spectra is observed. In the quark model, radially and orbitally excited $Ξ_b^-$ resonances with quark content $bds$ are expected. Referring to this peak as $Ξ_b(6227)^-$, the mass and natural width are measured to be $m_{Ξ_{b}(6227)^-}=6226.9\pm2.0\pm0.3\pm0.2$ MeV/$c^2$ and $Γ_{Ξ_b(6227)^-}=18.1\pm5.4\pm1.8$ MeV/$c^2$, where the first uncertainty is statistical, the second is systematic, and the third, on $m_{Ξ_b(6227)^-}$, is due to the knowledge of the $Λ_b^0$ baryon mass. Relative production rates of the ${Ξ_b(6227)^-\toΛ_b^0K^-}$ and ${Ξ_b(6227)^-\toΞ_b^0π^-}$ decays are also reported.
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Submitted 16 August, 2018; v1 submitted 23 May, 2018;
originally announced May 2018.
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Neutron background signal in superheated droplet detectors of the Phase II SIMPLE dark matter search
Authors:
A. C. Fernandes,
A. Kling,
M. Felizardo,
T. A. Girard,
A. R. Ramos,
J. G. Marques,
M. I. Prudêncio,
R. Marques,
F. P. Carvalho,
I. Lázaro
Abstract:
The simulation of the neutron background for Phase II of the SIMPLE direct dark matter search experiment is fully reported with various improvements relative to previous estimates. The model employs the Monte Carlo MCNP neutron transport code, using as input a realistic geometry description, measured radioassays and material compositions, and tabulated (α,n) yields and spectra. Developments includ…
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The simulation of the neutron background for Phase II of the SIMPLE direct dark matter search experiment is fully reported with various improvements relative to previous estimates. The model employs the Monte Carlo MCNP neutron transport code, using as input a realistic geometry description, measured radioassays and material compositions, and tabulated (α,n) yields and spectra. Developments include the accounting of recoil energy distributions, consideration of additional reactions and materials and examination of the relevant (α,n) data. A thorough analysis of the simulation results is performed that addresses an increased number of non-statistical uncertainties. The referred omissions are seen to provide a net increase of 13$\%$ in the previously-reported background estimates whereas the non-statistical uncertainty rises to 25$\%$. The final estimated recoil event rate is 0.372 $\pm$ 0.002 (stat.) $\pm$ 0.097 (non-stat.) evt/kgd resulting in insignificant changes over the results of the experiment.
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Submitted 4 December, 2015; v1 submitted 16 April, 2015;
originally announced April 2015.
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The SIMPLE Phase II Dark Matter Search
Authors:
M. Felizardo,
TA Girard,
T. Morlat,
A. C. Fernandes,
A. R. Ramos,
J. G. Marques,
A. Kling,
J. Puibasset,
M. Auguste,
D. Boyer,
A. Cavaillou,
J. Poupeney,
C. Sudre,
F. P. Carvalho,
M. I. Prudencio,
R. Marques
Abstract:
Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched for astroparticle dark matter using superheated liquid C$_{2}$ClF$_{5}$ droplet detectors. Each droplet generally requires an energy deposition with linear energy transfer (LET) $\gtrsim$ 150 keV/$μ$m for a liquid-to-gas phase transition, providing an intrinsic rejection against minimum ionizing particles of orde…
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Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments) searched for astroparticle dark matter using superheated liquid C$_{2}$ClF$_{5}$ droplet detectors. Each droplet generally requires an energy deposition with linear energy transfer (LET) $\gtrsim$ 150 keV/$μ$m for a liquid-to-gas phase transition, providing an intrinsic rejection against minimum ionizing particles of order 10$^{-10}$, and reducing the backgrounds to primarily $α$ and neutron-induced recoil events. The droplet phase transition generates a millimetric-sized gas bubble which is recorded by acoustic means. We describe the SIMPLE detectors, their acoustic instrumentation, and the characterizations, signal analysis and data selection which yield a particle-induced, "true nucleation" event detection efficiency of better than 97% at a 95% C.L. The recoil-$α$ event discrimination, determined using detectors first irradiated with neutrons and then doped with alpha emitters, provides a recoil identification of better than 99%; it differs from those of COUPP and PICASSO primarily as a result of their different liquids with lower critical LETs. The science measurements, comprising two shielded arrays of fifteen detectors each and a total exposure of 27.77 kgd, are detailed. Removal of the 1.94 kgd Stage 1 installation period data, which had previously been mistakenly included in the data, reduces the science exposure from 20.18 to 18.24 kgd and provides new contour minima of $σ_{p}$ = 4.3 $\times$ 10$^{-3}$ pb at 35 GeV/c$^{2}$ in the spin-dependent sector of WIMP-proton interactions and $σ_{N}$ = 3.6 $\times$ 10$^{-6}$ pb at 35 GeV/c$^{2}$ in the spin-independent sector. These results are examined with respect to the fluorine spin and halo parameters used in the previous data analysis.
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Submitted 16 April, 2014;
originally announced April 2014.
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Final Analysis and Results of the Phase II SIMPLE Dark Matter Search
Authors:
M. Felizardo,
T. A. Girard,
T. Morlat,
A. C. Fernandes,
A. R. Ramos,
J. G. Marques,
M. Auguste,
D. Boyer,
A. Cavaillou,
J. Poupeney,
C. Sudre,
J. Puibasset,
H. S. Miley,
R. F. Payne,
F. P. Carvalho,
M. I. Prudêncio,
R. Marques
Abstract:
We report the final results of the Phase II SIMPLE measurements, comprising two run stages of 15 superheated droplet detectors each, the second stage including an improved neutron shielding. The analyses includes a refined signal analysis, and revised nucleation efficiency based on reanalysis of previously-reported monochromatic neutron irradiations. The combined results yield a contour minimum of…
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We report the final results of the Phase II SIMPLE measurements, comprising two run stages of 15 superheated droplet detectors each, the second stage including an improved neutron shielding. The analyses includes a refined signal analysis, and revised nucleation efficiency based on reanalysis of previously-reported monochromatic neutron irradiations. The combined results yield a contour minimum of σ_{p} = 4.2 x 10^-3 pb at 35 GeV/c^2 on the spin-dependent sector of WIMP-proton interactions, the most restrictive to date from a direct search experiment and overlapping for the first time results previously obtained only indirectly. In the spin-independent sector, a minimum of 3.6 x 10^-6 pb at 35 GeV/c^2 is achieved, with the exclusion contour challenging the recent CoGeNT region of current interest.
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Submitted 9 April, 2012; v1 submitted 15 June, 2011;
originally announced June 2011.
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Improving Human-Computer Interaction by Developing Culture-sensitive Applications based on Common Sense Knowledge
Authors:
Junia Coutinho Anacleto,
Aparecido Fabiano Pinatti de Carvalho
Abstract:
The advent of Web 3.0, claiming for personalization in interactive systems (Lassila & Hendler, 2007), and the need for systems capable of interacting in a more natural way in the future society flooded with computer systems and devices (Harper et al., 2008) show that great advances in HCI should be done. This chapter presents some contributions of LIA for the future of HCI, defending that using…
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The advent of Web 3.0, claiming for personalization in interactive systems (Lassila & Hendler, 2007), and the need for systems capable of interacting in a more natural way in the future society flooded with computer systems and devices (Harper et al., 2008) show that great advances in HCI should be done. This chapter presents some contributions of LIA for the future of HCI, defending that using common sense knowledge is a possibility for improving HCI, especially because people assign meaning to their messages based on their common sense and, therefore, the use of this knowledge in developing user interfaces can make them more intuitive to the end-user. Moreover, as common sense knowledge varies from group to group of people, it can be used for developing applications capable of giving different feedback for different target groups, as the applications presented along this chapter illustrate, allowing, in this way, interface personalization taking into account cultural issues. For the purpose of using common sense knowledge in the development and design of computer systems, it is necessary to provide an architecture that allows it. This chapter presents LIAs approaches for common sense knowledge acquisition, representation and use, as well as for natural language processing, contributing with those ones who intent to get into this challenging world to get started.
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Submitted 3 January, 2010;
originally announced January 2010.