-
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 the decay Bs -> D*-+ \pi+- is presented using a data sample
corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions
collected by LHCb. This decay is expected to be mediated by a W-exchange
diagram, with little contribution from rescattering processes, and therefore a
measurement of the branching fraction will help to understand the mechanism
behind related decays such as Bs -> \pi+ \pi- and Bs -> D Dbar. Systematic
uncertainties are minimised by using B0 -> D*-+ \pi+- as a normalisation
channel. We find no evidence for a signal, and set an upper limit on the
branching fraction of BR(Bs -> D*-+ \pi+-) < 6.1 (7.8) x10^(-6) at 90% (95%)
confidence level.
02/2013;
-
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: First observations of the $B^0_s \rightarrow \psi(2S) \eta$, $B^0 \rightarrow
\psi(2S) \pi^+ \pi^-$ and $B^0_s \rightarrow \psi(2S) \pi^+ \pi^-$ decays are
made using a dataset corresponding to an integrated luminosity of 1.0~$fb^{-1}$
collected by the LHCb experiment in proton-proton collisions at a
centre-of-mass energy of $\sqrt{s}=7$ TeV. The ratios of the branching
fractions of each of the $\psi(2S)$ modes with respect to the corresponding
$J/\psi$ decays are \[ \frac{\mathcal{B}(B^0_s \rightarrow \psi(2S) \eta)
}{\mathcal{B}(B^0_s \rightarrow J/\psi \eta)}
=0.83\pm0.14\,(stat)\pm0.12\,(syst)\pm0.02\,(\mathcalB}), \] \[
\frac{\mathcal{B}(B^0 \rightarrow \psi(2S) \pi^+ \pi^-)}{\mathcal{B}(B^0
\rightarrow J/\psi \pi^+ \pi^-)}
=0.56\pm0.07\,(stat)\pm0.05\,(syst)\pm0.01\,(\mathcal{B}), \] \[
\frac{\mathcal{B}(B^0_s \rightarrow \psi(2S) \pi^+ \pi^-)}{\mathcal{B}(B^0_s
\rightarrow J/\psi \pi^+ \pi^-)}
=0.34\pm0.04\,(stat)\pm0.03\,(syst)\pm0.01\,(\mathcal{B}), \] where the third
uncertainty corresponds to the uncertainties of the dilepton branching
fractions of the $J/\psi$ and $\psi(2S)$ meson decays.
02/2013;
-
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 quantum numbers of the X(3872) meson are determined to be JPC = 1++ based
on angular correlations in B+ to X(3872) K+ decays, where X(3872) to pi+pi-
J/psi and J/psi to \mu+\mu-. The data correspond to 1.0 fb-1 of pp collisions
collected by the LHCb detector. The only alternative assignment allowed by
previous measurements, JPC=2-+, is rejected with a confidence level equivalent
to more than eight Gaussian standard deviations using the likelihood-ratio test
in the full angular phase space. This result favors exotic explanations of the
X(3872) state.
02/2013;
-
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: First observations and measurements of the branching fractions of the
$\bar{B}_s^0\to D^+D^-$, $\bar{B}_s^0\to D_s^+D^-$ and $\bar{B}_s^0\to
D^0\bar{D}^0$ decays are presented using 1.0 fb$^{-1}$ of data collected by the
LHCb experiment. These branching fractions are normalized to those of
$\bar{B}^0\to D^+D^-$, $B^0\to D_s^+D^-$ and $B^-\to D^0D_s^-$, respectively.
An excess of events consistent with the decay $\bar{B}^0\to D^0\bar{D}^0$ is
also seen, and its branching fraction is measured relative to that of $B^-\to
D^0D_s^-$. Improved measurements of the branching fractions
${\cal{B}}(\bar{B}_s^0\to D_s^+D_s^-)$ and ${\cal{B}}(B^-\to D^0D_s^-)$ are
reported, each relative to ${\cal{B}}(B^0\to D_s^+D^-)$. The ratios of
branching fractions are {-0.2in} {center} {align*} {{\cal{B}}(\bar{B}_s^0\to
D^+D^-)\over {\cal{B}}(\bar{B}^0\to D^+D^-)} &= 1.08\pm 0.20\pm0.10,
{{\cal{B}}(\bar{B}_s^0\to D_s^+D^-)\over {\cal{B}}(B^0\to D_s^+D^-)} &=
0.050\pm 0.008\pm0.004, {{\cal{B}}(\bar{B}_s^0\to D^0\bar{D}^0)\over
{\cal{B}}(B^-\to D^0D_s^-)} &= 0.019\pm 0.003\pm0.003, {{\cal{B}}(\bar{B}^0\to
D^0\bar{D}^0)\over {\cal{B}}(B^-\to D^0D_s^-)} &= 0.0014\pm
0.0006\pm0.0002,{{\cal{B}}(\bar{B}_s^0\to D_s^+D_s^-)\over {\cal{B}}(B^0\to
D_s^+D^-)} &= 0.56\pm 0.03\pm0.04, {{\cal{B}}(B^-\to D^0D_s^-)\over
{\cal{B}}(B^0\to D_s^+D^-)} &= 1.22\pm 0.02\pm0.07, {align*} {center} \noindent
where the uncertainties are statistical and systematic, respectively.
02/2013;
-
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 angular analysis of Lambda_b0 -> J/psi Lambda decays is performed using a
data sample corresponding to 1.0 fb^{-1} collected in pp collisions at sqrt(s)
= 7 TeV with the LHCb detector at the LHC. A parity violating asymmetry
characterising the Lambda_b0 -> J/psi Lambda decay of -0.04 +/- 0.17 +/- 0.07
and a Lambda_b0 transverse production polarisation of 0.05 +/- 0.07 +/- 0.02
are measured, where the first uncertainty is statistical and the second
systematic.
02/2013;
-
B. Aubert,
D. Boutigny,
J.-M. Gaillard,
A. Hicheur,
Y. Karyotakis, J. P. Lees,
P. Robbe,
V. Tisserand,
A. Palano,
A. Pompili, [......],
F. Di Lodovico,
Y. Pan,
R. Prepost,
I. J. Scott,
S. J. Sekula,
J. H. von Wimmersperg-Toeller,
S. L. Wu,
Z. Yu,
T. M. B. Kordich,
H. Neal
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. The data sample consists of 29.7 fb-1 recorded at the Υ(4S) resonance and 3.9 fb-1 off resonance. One of the neutral B mesons, which are produced in pairs at the Υ(4S), is fully reconstructed in the CP decay modes J/ψKS0, ψ(2S)KS0, χc1KS0, J/ψK*0 (K*0→KS0π0) and J/ψKL0, or in flavor-eigenstate modes involving D(*)π/ρ/a1 and J/ψK*0 (K*0→K+π-). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clear lepton or kaon tag. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. Wrong-tag probabilities, the time-difference resolution function, and the B0-B0 oscillation frequency Δmd are measured with a sample of about 6350 fully-reconstructed B0 decays in hadronic flavor-eigenstate modes. A maximum-likelihood fit to this flavor eigenstate sample finds Δmd=0.516±0.016(stat)±0.010(syst)ps-1. The value of the asymmetry amplitude sin2β is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged B0 decays in the CP-eigenstate modes. We find sin2β=0.59±0.14(stat)±0.05(syst), demonstrating that CP violation exists in the neutral B meson system. We also determine the value of the CP violation parameter |λ|=0.93±0.09(stat)±0.03(syst), which is consistent with the expectation of |λ|=1 for no direct CP violation.
Physical Review D 02/2013; 66(3). · 4.56 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We search for di-muon decays of a low-mass Higgs boson (A0) produced in radiative Υ(1S) decays. The Υ(1S) sample is selected by tagging the pion pair in the Υ(2S,3S)→π+π-Υ(1S) transitions, using a data sample of 92.8×106 Υ(2S) and 116.8×106 Υ(3S) events collected by the BABAR detector. We find no evidence for A0 production and set 90% confidence level upper limits on the product branching fraction B(Υ(1S)→γA0)×B(A0→μ+μ-) in the range of (0.28-9.7)×10-6 for 0.212≤mA0≤9.20 GeV/c2. The results are combined with our previous measurements of Υ(2S,3S)→γA0, A0→μ+μ- to set limits on the effective coupling of the b quark to the A0.
Physical Review D (rapid communication). 02/2013; 87(031102):8.
-
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: Charm production at the LHC in pp collisions at sqrt(s)=7 TeV is studied with
the LHCb detector. The decays D0 -> K- pi+, D+ -> K- pi+ pi+, D*+ -> D0(K- pi+)
pi+, D_s+ -> phi(K- K+) pi+, Lambda_c+ -> p K- pi+, and their charge conjugates
are analysed in a data set corresponding to an integrated luminosity of 15
nb^{-1}. Differential cross-sections dsigma/dp_T are measured for prompt
production of the five charmed hadron species in bins of transverse momentum
and rapidity in the region 0 < p_T < 8 GeV/c and 2.0 < y < 4.5. Theoretical
predictions are compared to the measured differential cross-sections. The
integrated cross-sections of the charm hadrons are computed in the above p_T-y
range, and their ratios are reported. A combination of the five integrated
cross-section measurements gives
sigma(c\bar{c})_{p_T < 8 GeV/c, 2.0 < y < 4.5} = 1419 +/- 12 (stat) +/- 116
(syst) +/- 65 (frag) microbarn,
where the uncertainties are statistical, systematic, and due to the
fragmentation functions.
02/2013;
-
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: An amplitude analysis of the final state structure in the Bs->J/\psi K+K-
decay mode is performed using 1.0/fb of data collected by the LHCb experiment
in 7 TeV center-of-mass energy pp collisions produced by the LHC. A modified
Dalitz plot analysis of the final state is performed using both the invariant
mass spectra and the decay angular distributions. Resonant structures are
observed in the K+K- mass spectrum as well as a significant non-resonant S-wave
contribution. The largest resonant component is the \phi(1020), accompanied by
f0(980), f'2(1525), and four additional resonances. The overall branching
fraction is measured to be B(Bs->J/\psi K+K-)=(7.70 +/-0.08 +/- 0.39 +/- 0.60)x
10^(-4), where the first uncertainty is statistical, the second systematic, and
the third due to the ratio of the number of Bs to B- mesons produced. The mass
and width of the f'2(1525) are measured to be 1522.2 +/- 2.8^{+5.3}_{-2.0} MeV
and 84 +/- 6^{+10}_{-5} MeV, respectively. The final state fractions of the
other resonant states are also reported.
02/2013;
-
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: Bottom baryons decaying to a J/\psi\ meson and a hyperon are reconstructed
using 1.0 fb^{-1} of data collected in 2011 with the LHCb detector. Significant
\Lambda_b^0 \rightarrow J/\psi \Lambda, \Xi_b^-\rightarrow J/\psi \Xi^- and
\Omega_b^- \rightarrow J/\psi \Omega^- signals are observed and the
corresponding masses are measured to be M(\Lambda_b^0) = 5619.53 \pm 0.13
(stat) \pm 0.45 (syst) MeV/c^2, M(\Xi_b^-) = 5795.8 \pm 0.9 (stat) \pm 0.4
(syst) MeV/c^2, M(\Omega_b^-) = 6046.0 \pm 2.2 (stat) \pm 0.5 (syst) MeV/c^2,
while the differences with respect to the \Lambda_b^0 mass are
M(\Xi_b^-)-M(\Lambda_b^0) = 176.2 \pm 0.9 (stat) \pm 0.1 (syst) MeV/c^2,
M(\Omega_b^-)-M(\Lambda_b^0) = 426.4 \pm 2.2 (stat) \pm 0.4 (syst) MeV/c^2.
These are the most precise mass measurements of the \Lambda_b^0, \Xi_b^- and
\Omega_b^- baryons to date. Averaging the above \Lambda_b^0 mass measurement
with that published by LHCb using 35 pb^{-1} of data collected in 2010 yields
M(\Lambda_b^0) = 5619.44 \pm 0.13 (stat) \pm 0.38 (syst) MeV/c^2.
02/2013;
-
The Babar Collaboration, J. P. Lees,
V. Poireau,
V. Tisserand,
E. Grauges,
A. Palano,
G. Eigen,
B. Stugu,
D. N. Brown,
L. T. Kerth, [......],
R. J. Sobie,
N. Tasneem,
T. J. Gershon,
P. F. Harrison,
T. E. Latham,
H. R. Band,
S. Dasu,
Y. Pan,
R. Prepost,
S. L. Wu
[show abstract]
[hide abstract]
ABSTRACT: We study the decay
$\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}$, reconstructing
the \Lambda_{c}^{+} baryon in the $p K^{-}\pi^{+}$ mode, using a data sample of
$467\times 10^{6}$ $B\bar{B}$ pairs collected with the BaBar detector at the
PEP-2 storage rings at SLAC. We measure branching fractions for decays with
intermediate $\Sigma_{c}$ baryons to be ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2455)^{++}\bar{p}\pi^{-}]=(21.3 \pm 1.0 \pm
1.0 \pm 5.5) \times 10^{-5}$, ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2520)^{++}\bar{p}\pi^{-}]=(11.5\pm 1.0 \pm
0.5 \pm 3.0)\times 10^{-5}$, ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2455)^{0}\bar{p}\pi^{+}]=(9.1 \pm 0.7 \pm
0.4 \pm 2.4)\times10^{-5}$, and ${\cal
B}[\bar{B}^{0}\rightarrow\Sigma_{c}(2520)^{0}\bar{p}\pi^{+}]= (2.2 \pm 0.7 \pm
0.1\pm 0.6) \times 10^{-5}$, where the uncertainties are statistical,
systematic, and due to the uncertainty on the
$\Lambda_{c}^{+}\rightarrow\proton\Km\pi^{+}$ branching fraction, respectively.
For decays without $\Sigma_{c}(2455)$ or $\Sigma_{c}(2520)$ resonances, we
measure ${\cal
B}[\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}]_{\mathrm{non-\Sigma_{c}}}=(79
\pm 4 \pm 4 \pm 20)\times10^{-5}$. The total branching fraction is determined
to be ${\cal
B}[\bar{B}^{0}\rightarrow\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}]_{\mathrm{total}}=(123
\pm 5 \pm 7 \pm 32)\times10^{-5}$. We examine multibody mass combinations in
the resonant three-particle $\Sigma_{c}\bar{p}\pi$ final states and in the
four-particle $\Lambda_{c}^{+}\bar{p}\pi^{+}\pi^{-}$ final state, and observe
different characteristics for the $\bar{p}\pi$ combination in neutral versus
doubly-charged $\Sigma_{c}$ decays.
02/2013;
-
D. Buskulic,
D. Casper,
I. De Bonis,
D. Decamp,
P. Ghez,
C. Goy, J. -P. Lees,
M. -N. Minard,
P. Odier,
B. Pietrzyk, [......],
I. Siotis,
A. Vayaki,
K. Zachariadou,
A. Blondel,
G. Bonneaud,
J. C. Brient,
P. Bourdon,
L. Passalacqua,
A. Rougé,
M. Rumpf
-
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: Exclusive $J/\psi$ and $\psi(2S)$ vector meson production has been observed
in the dimuon channel using the LHCb detector. The cross-section times
branching fractions to two muons with pseudorapidities between 2.0 and 4.5 are
measured to be $ \sigma_{pp\rightarrow J/\psi (\rightarrow \mu^{+} \mu^{-})}
(2.0 <\eta_{\mu^{\pm}}< 4.5) = 307 \pm 21 \pm 36 \text{pb},
\sigma_{pp\rightarrow \psi(2S) (\rightarrow \mu^{+} \mu^{-})} (2.0
<\eta_{\mu^{\pm}}< 4.5) = 7.8 \pm 1.3 \pm 1.0 \text{pb}, $ where the first
uncertainties are statistical and the second are systematic. The measurements
are found to be in good agreement with results from previous experiments and
theoretical predictions. The $J/\psi$ photoproduction cross-section has been
measured as a function of the photon-proton centre-of-mass energy. The results
are consistent with measurements obtained at HERA and confirm a similar power
law behaviour for the photoproduction cross-section.
01/2013;
-
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: The relative production rate of $B^{0}_{s}$ and $B^{0}$ mesons is determined
with the hadronic decays $B^{0}_{s} \rightarrow D^{-}_{s}\pi^{+}$ and $B^0
\rightarrow D^{-}K^{+}$. The measurement uses data corresponding to 1.0
fb$^{-1}$ of $pp$ collisions at a centre-of-mass energy of $\sqrt{s}=7$ TeV
recorded in the forward region with the LHCb experiment. The ratio of
production rates, $f_{s}/f_{d}$, is measured to be $0.238 \pm 0.004 \pm 0.015
\pm 0.021 $, where the first uncertainty is statistical, the second systematic,
and the third theoretical. This is combined with a previous LHCb measurement to
obtain $f_{s}/f_{d} = 0.256 \pm 0.020$. The dependence of $f_{s}/f_{d}$ on the
transverse momentum and pseudorapidity of the $B$ meson is determined using the
decays $B^{0}_{s} \rightarrow D^{-}_{s}\pi^{+}$ and $B^{0} \rightarrow
D^{-}\pi^{+}$. There is evidence for a decrease with increasing transverse
momentum, whereas the ratio remains constant as a function of pseudorapidity.
In addition, the ratio of branching fractions of the decays $B^{0} \rightarrow
D^{-}K^{+}$ and $B^{0} \rightarrow D^{-}\pi^{+}$ is measured to be $0.0822 \pm
0.0011 (\textrm{stat}) \pm 0.0025 (\textrm{syst})$.
01/2013;
-
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: Interpretation of CP violation measurements using charmonium decays, in both
the B0 and Bs systems, can be subject to changes due to "penguin" type
diagrams. These effects can be investigated using measurements of the
Cabibbo-suppressed B0->J/\psi pi+pi- decays. The final state composition of
this channel is investigated using a 1.0/fb sample of data produced in 7 TeV pp
collisions at the LHC and collected by the LHCb experiment. A modified Dalitz
plot analysis is performed using both the invariant mass spectra and the decay
angular distributions. An improved measurement of the B0->J/\psi pi+pi-
branching fraction of (3.97 +/-0.09+/- 0.11 +/- 0.16)x10^{-5} is reported where
the first uncertainty is statistical, the second is systematic and the third is
due to the uncertainty of the branching fraction of the decay B- -> J/\psi K-
used as a normalization channel. In the J/\psi pi+pi- final state significant
production of f0(500) and rho(770) resonances is found, both of which can be
used for CP violation studies. In contrast evidence for the f0(980) resonance
is not found, thus establishing the first upper limit on the branching fraction
product B(B0->J/\psi f0(980) x B(f0(980)-> pi+ pi-) < 1.1x10^{-6}, leading to
an upper limit on the absolute value of the mixing angle of the f0(980)$ with
the f0(500) of <31 degrees, both at 90% confidence level.
01/2013;
-
R Aaij,
C Abellan Beteta,
A Adametz,
B Adeva,
M Adinolfi,
C Adrover,
A Affolder,
Z Ajaltouni,
J Albrecht,
F Alessio, [......],
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: A measurement of the CP asymmetry in B^{0}→K^{*0}μ^{+}μ^{-} decays is presented, based on 1.0 fb^{-1} of pp collision data recorded by the LHCb experiment during 2011. The measurement is performed in six bins of invariant mass squared of the μ^{+}μ^{-} pair, excluding the J/ψ and ψ(2S) resonance regions. Production and detection asymmetries are removed using the B^{0}→J/ψK^{*0} decay as a control mode. The integrated CP asymmetry is found to be -0.072±0.040(stat)±0.005(syst), consistent with the standard model.
Physical Review Letters 01/2013; 110(3):031801. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We describe a measurement of the time-integrated luminosity of the data
collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider
at the Upsilon(4S), Upsilon(3S) and Upsilon(2S) resonances and in a continuum
region below each resonance. We measure the time-integrated luminosity by
counting e+e- --> e+e- and (for the Upsilon(4S) only) e+e- --> mu+mu- candidate
events, allowing additional photons in the final state. We use data-corrected
simulation to determine the cross sections and reconstruction efficiencies for
these processes, as well as the major backgrounds. Due to the large cross
sections of e+e- --> e+e- and e+e- --> mu+mu-, the statistical uncertainties of
the measurement are substantially smaller than the systematic uncertainties.
The dominant systematic uncertainties are due to observed differences between
data and simulation, as well as uncertainties on the cross sections. For data
collected on the Upsilon(3S) and Upsilon(2S) resonances, an additional
uncertainty arises due to Upsilon --> e+e-X background. For data collected off
the Upsilon resonances, we estimate an additional uncertainty due to
time-dependent efficiency variations, which can affect the short off-resonance
runs. The relative uncertainties on the luminosities of the on-resonance
(off-resonance) samples are 0.43% (0.43%) for the Upsilon(4S), 0.58% (0.72%)
for the Upsilon(3S), and 0.68% (0.88%) for the Upsilon(2S).
01/2013;
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R Aaij,
C Abellan Beteta,
A Adametz,
B Adeva,
M Adinolfi,
C Adrover,
A Affolder,
Z Ajaltouni,
J Albrecht,
F Alessio, [......],
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: A search for the rare decays B_{s}^{0}→μ^{+}μ^{-} and B^{0}→μ^{+}μ^{-} is performed with data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb^{-1} of proton-proton collisions at sqrt[s]=8 TeV and 1.0 fb^{-1} at sqrt[s]=7 TeV. We observe an excess of B_{s}^{0}→μ^{+}μ^{-} candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3×10^{-4} corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of B(B_{s}^{0}→μ^{+}μ^{-})=(3.2_{-1.2}^{+1.5})×10^{-9}, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the standard model expectation. The observed number of B^{0}→μ^{+}μ^{-} candidates is consistent with the background expectation, giving an upper limit of B(B^{0}→μ^{+}μ^{-})<9.4×10^{-10} at 95% confidence level.
Physical Review Letters 01/2013; 110(2):021801. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating
angle gamma through the combination of various measurements involving B^{+-}
--> D K^{+-}, B^{+-} --> D^{*} K^{+-}, and B^{+-} --> D K^{*+-} decays
performed by the BaBar experiment at the PEP-II e^{+}e^{-} collider at SLAC
National Accelerator Laboratory. Using up to 474 million B\bar{B} pairs, we
obtain gamma = (69 ^{+17}_{-16})^\circ (modulo 180^\circ). The total
uncertainty is dominated by the statistical component, with the experimental
and amplitude-model systematic uncertainties amounting to +-4^\circ. The
corresponding two-standard-deviation region is 41^\circ < gamma < 102^\circ.
This result is inconsistent with gamma = 0 with a significance of 5.9 standard
deviations.
01/2013;
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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: The decay B0 -> D K*0 and the charge conjugate mode are studied using 1.0fb-1
of pp collision data collected by the LHCb experiment at sqrt(s) = 7TeV in
2011. The CP asymmetry between the B0 -> D K*0 and the B0bar -> D K*0bar decay
rates, with the neutral D meson in the CP-even final state K+K-, is found to be
A_d_KK = -0.45 +- 0.23 +- 0.02, where the first uncertainty is statistical
and the second is systematic. In addition, favoured B0 -> D K*0 decays are
reconstructed with the D meson in the non-CP eigenstate K+ pi-. The ratio of
the B-flavour averaged decay rates in D decays to CP and non-CP eigenstates is
measured to be
R_d_KK = 1.36 (+0.37) (-0.32) +- 0.07, where the ratio of the branching
fractions of D0 -> K- pi+ to D0 -> K+ K- decays is included as multiplicative
factor. The CP asymmetries measured with two control channels, the favoured B0
-> DK*0 decay with D -> K+ pi- and the Bs0bar -> D K*0 decay with D K+ K-, are
also reported.
12/2012;
