Publications (110)0.57 Total impact
-
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: We report a measurement of the time-dependent ratio of D0->K+pi- to D0->K-pi+
decay rates in D*+-tagged events using 1.0 fb^{-1} of integrated luminosity
recorded by the LHCb experiment. We measure the mixing parameters
x'2=(-0.9+-1.3)x10^{-4}, y'=(7.2+-2.4)x10^{-3} and the ratio of
doubly-Cabibbo-suppressed to Cabibbo-favored decay rates
R_D=(3.52+-0.15)x10^{-3}, where the uncertainties include statistical and
systematic sources. The result excludes the no-mixing hypothesis with a
probability corresponding to 9.1 standard deviations and represents the first
observation of D0-D0bar oscillations from a single measurement.
11/2012;
-
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: The $B^0$--$\bar B^0$ oscillation frequency $\Delta m_d$ is measured by the
LHCb experiment using a dataset corresponding to an integrated luminosity of
$1.0\,$fb$^{-1}$ of proton-proton collisions at $\sqrt{s} = 7\,$TeV, and is
found to be $\Delta m_d = 0.5156 \pm 0.0051\,($stat.$) \pm
0.0033\,($syst.$)\,$ps$^{-1}$. The measurement is based on results from
analyses of the decays $B^0 \to D^- \pi^+$ ($D^- \to K^+ \pi^- \pi^-$) and $B^0
\to J\ \psi K^{*0}$ ($J\ \psi \to \mu^+ \mu^-$, $K^{*0} \to K^+ \pi^-$) and
their charge conjugated modes.
10/2012;
-
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: A measurement of the CP asymmetry in B0 -> K*0 mu+ mu- decays is presented,
based on 1.0fb-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
mu+ mu- pair, excluding the J/psi and psi(2S) resonance regions. Production and
detection asymmetries are removed using the B0 -> J/Psi K*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.
10/2012;
-
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: The asymmetry in the production cross-section \sigma of D+/- mesons, A_P =
(\sigma(D+) - \sigma(D-))/(\sigma(D+) + \sigma(D-)), is measured in bins of
pseudorapidity \eta and transverse momentum p_T within the acceptance of the
LHCb detector. The result is obtained with a sample of D+ -> K_S pi+ decays
corresponding to an integrated luminosity of 1.0 fb^-1, collected in pp
collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider.
When integrated over the kinematic range 2.0 < p_T < 18.0 GeV/c and 2.20 < \eta
< 4.75, the production asymmetry is A_P = (-0.96+/-0.26+/-0.18)%. The
uncertainties quoted are statistical and systematic, respectively. The result
assumes that any direct CP violation in the D+ -> K_S pi+ decay is negligible.
No significant dependence on \eta or p_T is observed.
10/2012;
-
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: First evidence of the $B^0\to J/\psi\omega$ decay is found and the
$B_{s}^0\to J/\psi\eta$ and $B_{s}^0\to J/\psi\eta^{\prime}$ decays are studied
using a dataset corresponding to an integrated luminosity of 1.0
$\mathrm{fb}^{-1}$ collected by the LHCb experiment in proton-proton collisions
at a centre-of-mass energy of $\sqrt{s} = 7$ TeV. The branching fractions of
these decays are measured relative to that of the $\mathrm{B}^0\to
J/\psi\rho^0$ decay: $$\frac{Br(B^0\to J/\psi\omega)}{Br(B^0\to J/\psi\rho^0)}
= 0.89 \pm0.19(stat)^{+0.07}_{-0.13}(syst)$$ $$\frac{Br(B^0_s\to
J/\psi\eta)}{Br(B^0\to J/\psi\rho^0)} = 14.0 \pm
1.2(stat)^{+1.1}_{-1.5}(syst)^{+1.1}_{-1.0}(\frac{f_d}{f_s}),$$
$$\frac{Br(B^0_s\to J/\psi\eta^{\prime})}{Br(B^0\to J/\psi\rho^0)} =
12.7\pm1.1(stat)^{+0.5}_{-1.3}(syst)^{+1.0}_{-0.9}(\frac{f_d}{f_s}),$$ where
the last uncertainty is due to the knowledge of $f_d/f_s$, the ratio of b-quark
hadronization factors that accounts for the different production rate of $B^0$
and $B^0_s$ mesons. The ratio of the branching fractions of $B^0_s\to
J/\psi\eta^{\prime}$ and $B^0_s\to J/\psi\eta$ decays is measured to be $$
\frac{Br(B^0_s\to J/\psi\eta^{\prime})}{Br(B^0_s\to J/\psi\eta)} =
0.90\pm0.09(stat)^{+0.06}_{-0.02}(syst).$$
10/2012;
-
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: A discovery of the rare decay $B^{+} \rightarrow \pi^{+} \mu^{+} \mu^{-}$ is
presented. This decay is observed for the first time, with 5.2 $\sigma$
significance. The observation is made using $pp$ collision data, corresponding
to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector.
The measured branching fraction is (2.3 $\pm$ 0.6 (stat.) $\pm$ 0.1
(syst.))$\times 10^{-8}$, and the ratio of the $B^{+} \rightarrow \pi^{+}
\mu^{+} \mu^{-}$ and $B^{+} \rightarrow \K^{+} \mu^{+} \mu^{-}$ branching
fractions is measured to be 0.053 $\pm$ 0.014 (stat.) $\pm$ 0.001 (syst.).
10/2012;
-
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: Evidence for the hadronic annihilation decay mode $B^{+} \to D_s^{+}\phi$ is
found with greater than $3\sigma$ significance. The branching fraction and \CP
asymmetry are measured to be \mathcal{B}(B^{+} \to D_s^{+}\phi) &=&
(1.87^{+1.25}_{-0.73}({\rm stat}) \pm 0.19 ({\rm syst}) \pm 0.32 ({\rm norm}))
\times 10^{-6}, \mathcal{A}_{CP}(B^{+} \to D_s^{+}\phi) &=& -0.01 \pm 0.41
({\rm stat}) \pm 0.03 ({\rm syst}). The last uncertainty on $\mathcal{B}(B^{+}
\to D_s^{+}\phi)$ is from the branching fractions of the $B^+ \to D_s^+ \kern
0.2em\bar{\kern -0.2em D}{}^0$ normalization mode and intermediate resonance
decays. Upper limits are also set for the branching fractions of the related
decay modes $B^{+}_{(c)} \to D^{+}_{(s)} K^{*0}$, $B^{+}_{(c)} \to D^{+}_{(s)}
\kern 0.2em\bar{\kern -0.2em K}{}^{*0}$ and ${B_c^{+} \to D^{+}_{s}\phi}$,
including the result ${\mathcal{B}(B^+ \to D^+ K^{*0})} < 1.8 \times 10^{-6}$
at the 90% credibility level.
10/2012;
-
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: A binned Dalitz plot analysis of $B^\pm \to D K^\pm$ decays, with $D \to
K^0_{\rm S} \pi^+\pi^-$ and $D \to K^0_{\rm S} K^+ K^-$, is performed to
measure the CP-violating observables $x_{\pm}$ and $y_{\pm}$ which are
sensitive to the CKM angle $\gamma$. The analysis exploits 1.0 $\rm fb^{-1}$ of
data collected by the LHCb experiment. The study makes no model-based
assumption on the variation of the strong phase of the D decay amplitude over
the Dalitz plot, but uses measurements of this quantity from CLEO-c as input.
The values of the parameters are found to be $x_- = (0.0 \pm 4.3 \pm 1.5 \pm
0.6) \times 10^{-2}$, $y_- = (2.7 \pm 5.2 \pm 0.8 \pm 2.3) \times 10^{-2}$,
$x_+ = (-10.3 \pm 4.5 \pm 1.8 \pm 1.4)\times 10^{-2}$ and $y_+ = (-0.9 \pm 3.7
\pm 0.8 \pm 3.0)\times 10^{-2}$. The first, second, and third uncertainties are
the statistical, the experimental systematic, and the error associated with the
precision of the strong-phase parameters measured at CLEO-c, respectively.
These results correspond to $\gamma = (44^{\,+43}_{\,-38})^\circ$, with a
second solution at $\gamma \to \gamma + 180^\circ$, and $r_B = 0.07 \pm 0.04$,
where $r_B$ is the ratio between the suppressed and favoured B decay
amplitudes.
09/2012;
-
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: The angular distribution and differential branching fraction of the decay
$B^{+} \rightarrow K^{+}\mu^{+}\mu^{-}$ are studied with a dataset
corresponding to $1.0\,\mathrm{fb}^{-1}$ of integrated luminosity, collected by
the LHCb experiment. The angular distribution is measured in bins of dimuon
invariant mass squared and found to be consistent with Standard Model
expectations. Integrating the differential branching fraction over the full
dimuon invariant mass range yields a total branching fraction of
$\mathcal{B}(B^{+} \rightarrow K^{+}\mu^{+}\mu^{-}) = (4.36 \pm 0.15 \pm
0.18)\times 10^{-7}$. These measurements are the most precise to date of the
$B^{+} \rightarrow K^{+}\mu^{+}\mu^{-}$ decay.
09/2012;
-
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: A search for the decay KS -> mu+ mu- is performed, based on a data sample of
1.0 fb^-1 of pp collisions at \sqrt{s}=7 TeV collected by the LHCb experiment
at the Large Hadron Collider. The observed number of candidates is consistent
with the background-only hypothesis, yielding an upper limit of BR(KS -> mu+
mu-) < 11 (9) x 10^-9 at 95 (90)% confidence level. This limit is a factor of
thirty below the previous measurement.
09/2012;
-
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: The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 phi gamma has been measured using an integrated luminosity of 1.0 fb-1
of pp collision data collected by the LHCb experiment at a centre-of-mass
energy of sqrt(s)=7 TeV. The value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 ->
phi gamma) = 1.23 +/- 0.06(stat.) +/- 0.04(syst.) +/- 0.10(fs/fd), where the
first uncertainty is statistical, the second is the experimental systematic
uncertainty and the third is associated with the ratio of fragmentation
fractions fs/fd. Using the world average value for BR(B0 -> K*0 gamma), the
branching fraction BR(Bs0 -> phi gamma) is measured to be (3.5 +/- 0.4) x
10^{-5}.
The direct CP asymmetry in B0 -> K*0 gamma decays has also been measured with
the same data and found to be A(CP)(B0 -> K*0 gamma) = (0.8 +/- 1.7(stat.) +/-
0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the
previous experimental results and theoretical expectations.
09/2012;
-
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: The production of \chib1P mesons in $pp$ collisions at a centre-of-mass
energy of $7\tev$ is studied using $32\invpb$ of data collected with the \lhcb
detector. The $\chib1P$ mesons are reconstructed in the decay mode $\chib1P \to
\Y1S\g \to \mumu\g$. The fraction of \Y1S originating from \chib1P decays in
the \Y1S transverse momentum range $6 < \pt^{\Y1S} < 15\gevc$ and rapidity
range $2.0 < y^{\Y1S} < 4.5$ is measured to be $(20.7\pm 5.7\pm
2.1^{+2.7}_{-5.4})%$, where the first uncertainty is statistical, the second is
systematic and the last gives the range of the result due to the unknown \Y1S
and \chib1P polarizations.
09/2012;
-
LHCb collaboration,
A. Bharucha,
I. I. Bigi,
C. Bobeth,
M. Bobrowski,
J. Brod,
A. J. Buras,
C. T. H. Davies,
A. Datta,
C. Delaunay, [......],
C. Hadjivasiliou,
R. Mountain,
B. K. Pal,
A. Phan, W. Qian,
T. Skwarnicki,
S. Stone,
J. Wang,
Z. Xing,
L. Zhang
[show abstract]
[hide abstract]
ABSTRACT: During 2011 the LHCb experiment at CERN collected 1.0 fb-1 of sqrt{s} = 7 TeV
pp collisions. Due to the large heavy quark production cross-sections, these
data provide unprecedented samples of heavy flavoured hadrons. The first
results from LHCb have made a significant impact on the flavour physics
landscape and have definitively proved the concept of a dedicated experiment in
the forward region at a hadron collider. This document discusses the
implications of these first measurements on classes of extensions to the
Standard Model, bearing in mind the interplay with the results of searches for
on-shell production of new particles at ATLAS and CMS. The physics potential of
an upgrade to the LHCb detector, which would allow an order of magnitude more
data to be collected, is emphasised.
08/2012;
-
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: A search for the decay $B^0_s\rightarrow J/\psi K^{*0}$ with $K^{*0}
\rightarrow K^-\pi^+$ is performed with 0.37 fb$^{-1}$ of $pp$ collisions at
$\sqrt{s}$ = 7 TeV collected by the LHCb experiment, finding a $\Bs \to J\psi
K^-\pi^+$ peak of $114 \pm 11$ signal events. The $K^-\pi^+$ mass spectrum of
the candidates in the $B^0_s$ peak is dominated by the $K^{*0}$ contribution.
Subtracting the non-resonant $K^-\pi^+$ component, the branching fraction of
\BsJpsiKst is $(4.4_{-0.4}^{+0.5} \pm 0.8) \times 10^{-5}$, where the first
uncertainty is statistical and the second systematic. A fit to the angular
distribution of the decay products yields the \Kst polarization fractions $f_L
= 0.50 \pm 0.08 \pm 0.02$ and $f_{||} = 0.19^{+0.10}_{-0.08} \pm 0.02$.
08/2012;
-
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: The first observation of the decay B0 -> D0bar K+ K- is reported from an
analysis of 0.62 fb-1 of pp collision data collected with the LHCb detector.
Its branching fraction is measured relative to that of the topologically
similar decay B0 -> D0bar pi+ pi- to be BR(B0 -> D0bar K+ K-)/BR(B0 -> D0bar
pi+ pi-) = 0.056+-0.011+-0.007, where the first uncertainty is statistical and
the second is systematic. The significance of the signal is 5.8 sigma.
Evidence, with 3.8 sigma significance, for Bs -> D0bar K+ K- decays is also
presented, with a relative branching fraction of BR(Bs -> D0bar K+ K-)/BR(B0 ->
D0bar K+ K-) = 0.90+-0.27+-0.20.
07/2012;
-
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: A precise determination of the effective $B_s^0 \rightarrow K^+ K^-$ lifetime
can be used to constrain contributions from physics beyond the Standard Model
in the $B_s^0$ meson system. Conventional approaches select $B$ meson decay
products that are significantly displaced from the $B$ meson production vertex.
As a consequence, $B$ mesons with low decay times are suppressed, introducing a
bias to the decay time spectrum which must be corrected. This analysis uses a
technique that explicitly avoids a lifetime bias by using a neural network
based trigger and event selection. Using 1.0 fb$^{-1}$ of data recorded by the
LHCb experiment, the effective $B_s^0 \rightarrow K^+ K^-$ lifetime is measured
as $1.455 \pm 0.046 \; \mathrm{(stat.)} \pm 0.006 \; \mathrm{(syst.)} \,
\mathrm{ps}.$
07/2012;
-
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: A study of $D^+\KS$ and $D^0K^+$ final states is performed in a sample of
1.0/fb of $pp$ collision data collected at a centre-of-mass energy of
$\sqrt{s}=7$ TeV with the \lhcb detector. We confirm the existence of the
$D_{s1}^*(2700)^+$ and $D_{sJ}^*(2860)^+$ excited states and measure their
masses and widths to be {eqnarray} m(D_{s1}^*(2700)^+) &=& 2709.2 \pm
1.9({stat})\pm\,\,\,4.5({syst}) {MeV}/c^2,\cr \Gamma(D_{s1}^*(2700)^+) &=&
\,\,\,115.8 \pm 7.3({stat}) \pm12.1({syst}) {MeV}/c^2,\cr m(D_{sJ}^*(2860)^+)
&=& 2866.1 \pm 1.0({stat}) \pm\,\,\,6.3({syst}) {MeV}/c^2,\cr
\Gamma(D_{sJ}^*(2860)^+) &=& \,\,\,\,\,\,69.9 \pm 3.2({stat})
\pm\,\,\,6.6({syst}) {MeV}/c^2.\cr {eqnarray}
07/2012;
-
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: The effective lifetime of the Bs meson in the decay mode Bs->J/\psi f0(980)
is measured using 1.0/fb of data collected in pp collisions at sqrt(s) = 7 TeV
with the LHCb detector. The result is 1.700 +/- 0.040 +/- 0.026 ps where the
first uncertainty is statistical and the second systematic. As the final state
is CP-odd, and CP violation in this mode is measured to be small, the lifetime
measurement can be translated into a measurement of the decay width of the
heavy Bs mass eigenstate, \Gamma_H = (0.588 +/- 0.014 +/- 0.009)/ps.
07/2012;
-
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: The charged-particle production ratios $\bar{p}/p$, $K^-/K^+$, $\pi^-/\pi^+$,
$(p + \bar{p})/(\pi^+ + \pi^-)$, $(K^+ + K^-)/(\pi^+ + \pi^-)$ and $(p +
\bar{p})/(K^+ + K^-)$ are measured with the LHCb detector using $0.3 {\rm
nb^{-1}}$ of $pp$ collisions delivered by the LHC at $\sqrt{s} = 0.9$ TeV and
$1.8 {\rm nb^{-1}}$ at $\sqrt{s} = 7$ TeV. The measurements are performed as a
function of transverse momentum $p_{\rm T}$ and pseudorapidity $\eta$. The
production ratios are compared to the predictions of several Monte Carlo
generator settings, none of which are able to describe adequately all
observables. The ratio $\bar{p}/p$ is also considered as a function of rapidity
loss, $\Delta y \equiv y_{\rm beam} - y$, and is used to constrain models of
baryon transport.
06/2012;
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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, [......],
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: Based on data corresponding to an integrated luminosity of 0.37 fb^-1
collected by the LHCb experiment in 2011, the following ratios of branching
fractions are measured:
B(B0 -> pi+ pi-) / B(B0 -> K+pi-) = 0.262 +/- 0.009 +/- 0.017,
(fs/fd) * B(Bs -> K+K-) / B(B^0 -> K+pi-) = 0.316 +/- 0.009 +/- 0.019,
(fs/fd) * B(Bs ->pi+ K-) / B(B0 -> K+pi-) = 0.074 +/- 0.006 +/- 0.006,
(fd/fs) * B(B0 -> K+K-) / B(Bs -> K+K-) = 0.018 {+ 0.008 - 0.007} +/- 0.009,
(fs/fd) * B(Bs -> pi+pi-) / B(B0 -> pi+pi-) = 0.050 {+ 0.011 - 0.009} +/-
0.004,
B(Lambda_b -> p pi-) / B(Lambda_b -> p K-) = 0.86 +/- 0.08 +/- 0.05, where
the first uncertainties are statistical and the second systematic. Using the
current world average of B(B0 -> K+pi-) and the ratio of the strange to light
neutral B meson production fs/fd measured by LHCb, we obtain:
B(B0 -> pi+pi-) = (5.08 +/- 0.17 +/- 0.37) x 10^-6,
B(Bs -> K+K-) = (23.0 +/- 0.7 +/- 2.3) x 10^-6,
B(Bs -> pi+K-) = (5.4 +/- 0.4 +/- 0.6) x 10^-6,
B(B0 -> K+K-) = (0.11 {+ 0.05 - 0.04} +/- 0.06) x 10^-6,
B(Bs -> pi+pi-) = (0.95 {+ 0.21 - 0.17} +/- 0.13) x 10^-6.
The measurements of B(Bs -> K+K-), B(Bs -> pi+ K-) and B(B0 -> K+K-) are the
most precise to date. The decay mode Bs -> pi+pi- is observed for the first
time with a significance of more than 5 sigma.
06/2012;