Publications (123)0 Total impact
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: A combination of three LHCb measurements of the CKM angle \gamma\ is
presented. The decays B->DK and B->D\pi\ are used, where D denotes an admixture
of D0 and D0-bar mesons, decaying into KK, \pi\pi, K\pi, K\pi\pi\pi, KS\pi\pi,
or KSKK final states. Combining results from B->DK decays alone a best-fit
value of \gamma=70.5 deg is found, and confidence intervals are set \gamma\ in
[54.9, 85.4] deg at 68% CL, \gamma\ in [41.8, 98.1] deg at 95% CL.
The best-fit value of \gamma\ found from a combination of results from
B->D\pi\ decays alone, is \gamma=97.1 deg, and the confidence intervals \gamma\
in [8.8, 43.8] deg or [79.3, 137.4] deg or [165.8, 177.1] deg at 68% CL are
set, without constraint at 95% CL.
The combination of results from B->DK and B->D\pi\ decays gives a best-fit
value of \gamma=86.0 deg and the confidence intervals \gamma\ in [49.0, 72.5]
deg or [79.1, 94.2] deg at 68% CL, \gamma\ in [35.2, 105.6] deg at 95% CL are
set. All values are expressed modulo 180 deg.
05/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The determination of the differential branching fraction and the first
angular analysis of the decay $B_s^0\to\phi\mu^{+}\mu^{-}$ are presented using
data, corresponding to an integrated luminosity of $1.0\,{\rm fb}^{-1}$,
collected by the LHCb experiment at $\sqrt{s}=7\,{\rm TeV}$. The differential
branching fraction is determined in bins of $q^{2}$, the invariant dimuon mass
squared. Integration over the full $q^{2}$ range yields a total branching
fraction of ${\cal B}(B_s^0\to\phi\mu^{+}\mu^{-}) = (7.07\,^{+0.64}_{-0.59}\pm
0.17 \pm 0.71)\times 10^{-7}$, where the first uncertainty is statistical, the
second systematic, and the third originates from the branching fraction of the
normalisation channel. An angular analysis is performed to determine the
angular observables $F_{\rm L}$, $S_3$, $A_6$, and $A_9$. The observables are
consistent with Standard Model expectations.
05/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: Using three- and four-body decays of $D$ mesons produced in semileptonic
$b$-hadron decays, precision measurements of $D$ meson mass differences are
made together with a measurement of the $D^{0}$ mass. The measurements are
based on a dataset corresponding to an integrated luminosity of $1.0 fb^{-1}$
collected in $pp$ collisions at 7\,TeV. Using the decay $D^0 \rightarrow K^{+}
K^{-} K^{-} \pi^{+}$, the $D^0$ mass is measured to be $M(D^0) &=& 1864.75 \pm
0.15 \,({\rm stat}) \pm 0.11 \,({\rm syst}) \, \textrm{MeV/c^2}$. The mass
differences $M(D^{+}) - M(D^{0}) = 4.76 \pm 0.12 \,({\rm stat}) \pm 0.07
\,({\rm syst}) \, \textrm{MeV/c^2}$ and $M(D^{+}_s) - M(D^{+}) = 98.68 \pm 0.03
\,({\rm stat}) \pm 0.04 \,({\rm syst}) \, \textrm{MeV/c^2}$ are measured using
the $D^0 \rightarrow K^{+} K^{-} \pi^{+} \pi^{-}$ and $D^{+}_{(s)} \rightarrow
K^{+}K^{-} \pi^{+}$ modes.
04/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The production of J/psi and Upsilon mesons in pp collisions at sqrt(s) = 8
TeV is studied with the LHCb detector. The J/psi and Upsilon mesons are
reconstructed in the mu+mu- decay mode and the signal yields are determined
with a fit to the mu+mu- invariant mass distributions. The analysis is
performed in the rapidity range 2.0<y<4.5 and transverse momentum range
0<p_T<14(15) GeV/c of the J/psi(Upsilon) mesons. The J/psi and Upsilon
production cross-sections and the fraction of J/psi mesons from b-hadron decays
are measured as a function of the meson p_T and y.
04/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The first observation of the decay Bs -> D0bar K- {\pi}+ is reported. The
analysis is based on a data sample, corresponding to an integrated luminosity
of 1.0 fb-1 of pp collisions, collected with the LHCb detector. The branching
fraction relative to that of the topologically similar decay B0 -> D0bar {\pi}+
{\pi}- is measured to be BR(Bs -> D0bar K- {\pi}+)/BR(B0 -> D0bar {\pi}+
{\pi}-) = 1.18 +- 0.05 (stat.) +- 0.12 (syst.). In addition, the relative
branching fraction of the decay B0 -> D0bar K+ {\pi}- is measured to be BR(B0
-> D0bar K+ {\pi}-)/BR(B0 -> D0bar {\pi}+ {\pi}-) = 0.106 +- 0.007 (stat.) +-
0.008 (syst.).
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The angular distribution and differential branching fraction of the decay
$B^{0} \to K^{*0} \mu^{+}\mu^{-}$ are studied using a data sample, collected by
the LHCb experiment in $pp$ collisions at $\sqrt{s}=7\,{\rm TeV}$,
corresponding to an integrated luminosity of $1.0\,{\rm fb}^{-1}$. Several
angular observables are measured in bins of the dimuon invariant mass squared,
$q^{2}$. A first measurement of the zero-crossing point of the forward-backward
asymmetry of the dimuon system is also presented. The zero-crossing point is
measured to be $q_{0}^{2} = 4.9 \pm 0.9 \,{\rm GeV}^{2}/c^{4}$, where the
uncertainty is the sum of statistical and systematic uncertainties. The results
are consistent with the Standard Model predictions.
04/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: A search for non-resonant D+(s) to pi+mu+mu- and D+(s) to pi-mu+mu+ decays is
performed using proton-proton collision data, corresponding to an integrated
luminosity of 1.0 fb-1, at sqrt(s) = 7 TeV recorded by the LHCb experiment in
2011. No signals are observed and the 90% (95%) confidence level (CL) limits on
the branching fractions are
B(D+ to pi+mu+mu-) < 7.3 (8.3) x 10-8,
B(Ds+ to pi+mu+mu-) < 4.1 (4.8) x 10-7,
B(D+ to pi-mu+mu+) < 2.2 (2.5) x 10-8,
B(Ds+ to pi-mu+mu+) < 1.2 (1.4) x 10-7.
These limits are the most stringent to date.
04/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: Using pp collision data, corresponding to an integrated luminosity of $1.0
\mathrm{fb}^{-1}$, collected by LHCb in 2011 at a center-of-mass energy of 7
TeV, we report the measurement of direct CP violation in $B^0_s \to K^-\pi^+$
decays, $A_{C/!P}(B^0_s \rightarrow K^- \pi^+)=0.27 \pm 0.04\,\mathrm{(stat)}
\pm 0.01\,\mathrm{(syst)}$, with significance exceeding five standard
deviations. This is the first observation of CP violation in the decays of
$B^0_s$ mesons. Furthermore, we provide an improved determination of direct CP
violation in $B^0 \to K^+\pi^-$ decays, $A_{C/!P}(B^0\rightarrow K^+
\pi^-)=-0.080 \pm 0.007\,\mathrm{(stat)} \pm 0.003\,\mathrm{(syst)}$, which is
the most precise measurement of this quantity to date.
04/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: A key ingredient to searches for physics beyond the Standard Model in
$B^{0}_{s}$ mixing phenomena is the measurement of the
$B^{0}_{s}$-$\bar{B}^{0}_{s}$ oscillation frequency, which is equivalent to the
mass difference $\Delta m_{s}$ of the $B^{0}_{s}$ mass eigenstates. Using the
world's largest $B^{0}_{s}$ meson sample accumulated in a dataset,
corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by the
LHCb experiment at the CERN LHC in 2011, a measurement of $\Delta m_{s}$ is
presented. A total of about 34,000 $B^{0}_{s}\rightarrowD^{-}_{s}\pi^{+}$
signal decays are reconstructed, with an average decay time resolution of 44
fs. The oscillation frequency is measured to be \mbox{$\Delta m_{s}$ = 17.768
$\pm$ 0.023 (stat) $\pm$ 0.006 (syst) ps$^{-1}$}, which is the most precise
measurement to date.
04/2013;
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LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The decays $B^+_c \rightarrow J/\psi D_s^+$ and $B^+_c \rightarrow J/\psi
D_s^{*+}$ are observed for the first time using a dataset, corresponding to an
integrated luminosity of 3$fb^{-1}$, collected by the LHCb experiment in
proton-proton collisions at centre-of-mass energies of $\sqrt{s}$=7 and 8 TeV.
The statistical significance for both signals is in excess of 9 standard
deviations. The following ratios of branching fractions are measured to be
$BR(B^+_c \rightarrow J/\psi D_s^+)/BR(B^+_c \rightarrow J/\psi \pi+) = 2.90
\pm 0.57 \pm 0.24$, $BR(B^+_c \rightarrow J/\psi D_s^{*+}) / BR (B^+_c
\rightarrow J/\psi D_s^+) = 2.37 \pm 0.56 \pm 0.10$, where the first
uncertainties are statistical and the second systematic. The mass of the \Bc
meson is measured to be $m_{B^+_c} = 6276.28 \pm 1.44 (stat) \pm 0.36(syst)
MeV/c^2$, using the $B^+_c \rightarrow J/\psi D_s^+$ decay mode.
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: This paper reports the first measurement of the effective B_s^0 -> J/{\psi}
K_S^0 lifetime and an updated measurement of its time-integrated branching
fraction. Both measurements are performed with a data sample, corresponding to
an integrated luminosity of 1.0 fb^{-1} of pp collisions, recorded by the LHCb
experiment in 2011 at a centre-of-mass energy of 7 TeV. The results are:
tau_J/{\psi}K_S^0 = 1.75 +/- 0.12 (stat) +/- 0.07 (syst) and
BR(B_s^0 -> J/{\psi} K_S^0) = (1.97 +/- 0.23) X 10^{-5}.
For the latter measurement, the uncertainty includes both statistical and
systematic sources.
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: Searches for the lepton flavour violating decay $\tau^-\rightarrow
\mu^-\mu^+\mu^-$ and the lepton flavour and baryon number violating decays
$\tau^-\rightarrow \bar{p}\mu^+\mu^-$ and $\tau^-\rightarrow p\mu^-\mu^-$ have
been carried out using proton-proton collision data, corresponding to an
integrated luminosity of 1.0 fb$^{-1}$, taken by the LHCb experiment at
$\sqrt{s} = 7$ TeV. No evidence has been found for any signal, and limits have
been set at 90% confidence level on the branching fractions: $\cal
B(\tau^-\rightarrow \mu^-\mu^+\mu^-) < 8.0 \times 10^{-8}$, $\cal
B(\tau^-\rightarrow \bar{p}\mu^+\mu^-) < 3.3 \times 10^{-7}$ and $\cal
B(\tau^-\rightarrow p\mu^-\mu^-) < 4.4 \times 10^{-7}$. The results for the
$\tau^-\rightarrow \bar{p}\mu^+\mu^-$ and $\tau^-\rightarrow p\mu^-\mu^-$ decay
modes represent the first direct experimental limits on these channels.
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The branching fraction of the rate decay $B^0 \rightarrow K^{*0}e^+e^-$ in
the dilepton mass region from 30 to 1000 MeV$/c^2$ has been measured by the
LHCb experiment, using $pp$ collision data, corresponding to an integrated
luminosity of 1.0 fb$^{-1}$, at a centre-of-mass energy of 7 TeV. The decay
mode $B^0 \rightarrow J/\psi(e^+e^-) K^{*0}$ is utilized as a normalization
channel. The branching fraction $B^0 \rightarrow K^{*0}e^+e^-$ is measured to
be $$ B(B^0 \rightarrow K^{*0}e^+e^-)^{30-1000 MeV/c^2}= (3.1\, ^{+0.9\mbox{}
+0.2}_{-0.8\mbox{}-0.3} \pm 0.2)\times 10^{-7}, $$ where the first error is
statistical, the second is systematic, and the third comes from the
uncertainties on the B^0 \rightarrow J/\psi K^{*0}$ and $J/\psi \rightarrow
e^+e^- $ branching fractions.
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The time-dependent CP asymmetry in B_s^0\to J/\psi K^+K^- decays is measured
using $pp$ collision data at \sqrt{s}=7TeV, corresponding to an integrated
luminosity of 1.0fb^-1, collected with the LHCb detector. The decay time
distribution is characterised by the decay widths \Gamma_L and \Gamma_H of the
light and heavy mass eigenstates of the B_s^0--\bar{B}_s^0 system and by a
CP-violating phase \phi_s. In a sample of 27\,617 B_s^0\to J/\psi K^+K^-
decays, where the dominant contribution comes from B_s^0\to J/\psi\phi\ decays,
these parameters are measured to be
\phi_s = 0.07 \pm 0.09 (stat) \pm 0.01 (syst) rad,
\Gamma_s \equiv (\Gamma_L+\Gamma_H)/2 = 0.663 \pm 0.005 (stat) \pm 0.006
(syst) ps^-1,
\Delta\Gamma_s \equiv \Gamma_L -\Gamma_H = 0.100 \pm 0.016 (stat) \pm 0.003
(syst) & ps^-1, corresponding to the single most precise determination of
\phi_s, \Delta\Gamma_s and \Gamma_s. The result of performing a combined
analysis with B_s^{0} \to J/\psi \pi^+\pi^- decays gives
\phi_s = 0.01 \pm 0.07 (stat) \pm 0.01 (syst) rad,
\Gamma_s = 0.661 \pm 0.004 (stat) \pm 0.006 (syst) ps^-1,
\Delta\Gamma_s = 0.106 \pm 0.011 (stat) \pm 0.007 (syst) & ps^-1.
All measurements are in agreement with the Standard Model predictions.
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: Limits on the cross-section times branching fraction for neutral Higgs
bosons, produced in $pp$ collisions at $\sqrt{s} = 7$ TeV, and decaying to two
tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The
result is based on a dataset, corresponding to an integrated luminosity of 1.0
$\mathrm{fb}^{-1}$, collected with the LHCb detector. Candidates are identified
by reconstructing final states with two muons, a muon and an electron, a muon
and a hadron, or an electron and a hadron. A model independent upper limit at
the 95% confidence level is set on a neutral Higgs boson cross-section times
branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to
0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model
expectation. An upper limit on $\tan\beta$ in the Minimal Supersymmetric Model
is set in the $m_{h^0}^\mathrm{max}$ scenario. It ranges from 34 for a CP-odd
Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140
GeV.
04/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
A. Adametz,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht, [......],
O. Yushchenko,
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: Using proton-proton collision data collected by the LHCb experiment at
sqrt(s) = 7 TeV, corresponding to an integrated luminosity of 1.0 fb^{-1}, the
ratio of branching fractions of the B0 -> D*- pi+ pi- pi+ decay relative to the
B0 -> D*- pi+ decay is measured to be B(B0 -> D*- pi+ pi- pi+) / B(B0 -> D*-
pi+) = 2.64 \pm 0.04 (stat.) \pm 0.13 (syst.). The Cabibbo-suppressed decay B0
-> D*- K+ pi- pi+ is observed for the first time and the measured ratio of
branching fractions is B(B0 -> D*- K+ pi- pi+) / B(B0 -> D*- pi+ pi- pi+) =
(6.47 \pm 0.37 (stat.) \pm 0.35 (syst.)) x 10^{-2}. A search for orbital
excitations of charm mesons contributing to the B0 -> D*- pi+ pi- pi+ final
state is also performed, and the first observation of the B0 ->
Dbar_{1}(2420)^0 pi+ pi- decay is reported with the ratio of branching
fractions B(B0 -> (Dbar_{1}(2420)^0 -> D*- pi+) pi- pi+) / B(B0 -> D*- pi+ pi-
pi+) = (2.04 \pm 0.42 (stat.) \pm 0.22 (syst.)) x 10^{-2}, where the numerator
represents a product of the branching fractions B(B0 -> Dbar_{1}(2420)^0 pi-
pi+) and B(Dbar_{1}(2420)^0 -> D*- pi+).
03/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: An analysis of $B^{\pm}\to DK^{\pm}$ and $B^{\pm}\to D\pi^{\pm}$ decays is
presented where the $D$ meson is reconstructed in the four-body final state
$K^{\pm}\pi^{\mp} \pi^+ \pi^-$. Using LHCb data corresponding to an integrated
luminosity of $1.0{\rm \,fb}^{-1}$, first observations are made of the
suppressed ADS modes $B^{\pm}\to [\pi^{\pm} K^{\mp}\pi^+\pi^-]_D K^{\pm}$ and
$B^{\pm}\to [\pi^{\pm} K^{\mp} \pi^+\pi^- ]_D\pi^{\pm}$ with a significance of
$5.1\sigma$ and greater than $10\sigma$, respectively. Measurements of CP
asymmetries and CP-conserving ratios of partial widths from this family of
decays are also performed. The magnitude of the ratio between the suppressed
and favoured $B^{\pm}\to DK^{\pm}$ amplitudes is determined to be $r^K_B =
0.097 \pm{0.011}$.
03/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: A search for direct CP violation in D0 -> h- h+ (where h=K or pi) is
presented using data corresponding to an integrated luminosity of 1.0 fb^-1
collected in 2011 by LHCb in pp collisions at a centre-of-mass energy of 7 TeV.
The analysis uses D0 mesons produced in inclusive semileptonic b-hadron decays
to the D0 mu X final state, where the charge of the accompanying muon is used
to tag the flavour of the D0 meson. The difference in the CP-violating
asymmetries between the two decay channels is measured to be
Delta A_CP = A_CP(K-K+) - A_CP(pi-pi+) = (0.49 +- 0.30 (stat) +- 0.14 (syst))
% .
This result does not confirm the evidence for direct CP violation in the
charm sector reported in other analyses.
03/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht,
F. Alessio, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: The decay $B_c^+ \to \psi(2S)\pi^+$ with $\psi(2S) \to \mu^+\mu^-$ is
observed with a significance of $5.2\,\sigma$ using $pp$ collision data
corresponding to an integrated luminosity of $1.0\,\invfb$ collected by the
LHCb experiment. The branching fraction of $B_c^+ \to \psi(2S)\pi^+$ decays
relative to that of the $B_c^+ \to J/\psi\pi^+$ mode is measured to be
\begin{equation*} \frac{\mathcal{B}(B_c^+ \to \psi(2S)\pi^+)}{\mathcal{B}(B_c^+
\to J/\psi\pi^+)} = 0.250 \pm 0.068 \,\text{stat} \pm 0.014 \,\text{\syst} \pm
0.006 \,(\mathcal{B}). \end{equation*} The last term is the uncertainty on the
ratio $\mathcal{B}(\psi(2S) \to \mu^+\mu^-)/\mathcal{B}(J/\psi \to
\mu^+\mu^-)$.
03/2013;
-
LHCb collaboration,
R. Aaij,
C. Abellan Beteta,
A. Adametz,
B. Adeva,
M. Adinolfi,
C. Adrover,
A. Affolder,
Z. Ajaltouni,
J. Albrecht, [......],
M. Zangoli,
M. Zavertyaev,
F. Zhang,
L. Zhang,
W. C. Zhang,
Y. Zhang,
A. Zhelezov,
A. Zhokhov,
L. Zhong,
A. Zvyagin
[show abstract]
[hide abstract]
ABSTRACT: \noindent A search for the decays $B^0_{s}\rightarrow \mu^+ \mu^- \mu^+
\mu^-$ and $B^0 \rightarrow \mu^+ \mu^- \mu^+ \mu^-$ is performed using data,
corresponding to an integrated luminosity of
1.0\ensuremath{\{\,fb}^{-1}}\xspace, collected with the LHCb detector in 2011.
The number of candidates observed is consistent with the expected background
and, assuming phase-space models of the decays, limits on the branching
fractions are set: \{${\ensuremath{\cal B}\xspace}(B^0_{s}\rightarrow \mu^+
\mu^- \mu^+ \mu^-) < 1.6 \ (1.2) \times 10^{-8}$} and \{${\ensuremath{\cal
B}\xspace}(B^0 \rightarrow \mu^+ \mu^- \mu^+ \mu^-)< 6.6 \ (5.3) \times
10^{-9}$} at 95\,% (90\,%) confidence level. In addition, limits are set in the
context of a supersymmetric model which allows for the $B^0_{(s)}$ meson to
decay into a scalar ($S$) and pseudoscalar particle ($P$), where $S$ and $P$
have masses of 2.5 GeV and 214.3 MeV, respectively, both resonances decay into
$\mu^+\mu^-$. The branching fraction limits for these decays are
\{${\ensuremath{\cal B}\xspace}(\ensuremath{B^0_{s}\rightarrow SP}\xspace) <
1.6 \ (1.2) \times 10^{-8}$} and \{${\ensuremath{\cal
B}\xspace}(\ensuremath{B^0\rightarrow SP}\xspace)< 6.3 \ (5.1) \times 10^{-9}$}
at 95% (90%) confidence level.
03/2013;
Institutions
-
2011–2013
-
Sapienza University of Rome
Roma,
Latium,
Italy