A
bstract
A search for the doubly charmed baryon
$ \Xi_{cc}^{+} $
in the decay mode
$ \Xi_{cc}^{+}\to \Lambda_c^{+}{K^{-}}{\pi^{+}} $
is performed with a data sample, corresponding to an integrated ...luminosity of 0.65 fb
−1
, of
pp
collisions recorded at a centre-of-mass energy of 7 TeV. No significant signal is found in the mass range 3300-3800 MeV
/c
2
. Upper limits at the 95% confidence level on the ratio of the
$ \Xi_{cc}^{+} $
production cross-section times branching fraction to that of the
$ \Lambda_c^{+} $
,
R
, are given as a function of the
$ \Xi_{cc}^{+} $
mass and lifetime. The largest upper limits range from
R
< 1.5 × 10
−
2 for a lifetime of 100 fs to
R <
3
.
9 × 10
−4
for a lifetime of 400 fs.
A search for the CP-violating strong decays η→π+π− and η′(958)→π+π− has been performed using approximately 2.5×107 events of each of the decays D+→π+π+π− and Ds+→π+π+π−, recorded by the LHCb ...experiment. The data set corresponds to an integrated luminosity of 3.0 fb−1 of pp collision data recorded during LHC Run 1 and 0.3 fb−1 recorded in Run 2. No evidence is seen for D(s)+→π+η(′) with η(′)→π+π−, and upper limits at 90% confidence level are set on the branching fractions, B(η→π+π−)<1.6×10−5 and B(η′→π+π−)<1.8×10−5. The limit for the η decay is comparable with the existing one, while that for the η′ is a factor of three smaller than the previous limit.
A search for the rare two-body charmless baryonic decay B + → p$-\atop{Λ}$ is performed with pp collision data, corresponding to an integrated luminosity of 3 fb-1, collected by the LHCb experiment ...at centre-of-mass energies of 7 and 8 TeV. An excess of B + →p$-\atop{Λ}$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the B + →K S 0 π + decay for normalisation, B(B+→p$-\atop{Λ}$=2.4$+1.0\atop{0.8}$±0.3 x 10-7)where the first uncertainty is statistical and the second systematic.
Abstract A search for the rare two-body charmless baryonic decay B + → p Λ ¯ $$ {B}^{+}\to p\overline{\varLambda} $$ is performed with pp collision data, corresponding to an integrated luminosity of ...3 fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of B + → p Λ ¯ $$ {B}^{+}\to p\overline{\varLambda} $$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the B + → K S 0 π + decay for normalisation, is ℬ B + → p Λ ¯ = 2 . 4 − 0.8 + 1.0 ± 0.3 × 1 0 − 7 , $$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{\varLambda}\right)=\left(2.{4}_{-0.8}^{+1.0}\pm 0.3\right)\times 1{0}^{-7}, $$ where the first uncertainty is statistical and the second systematic.
A
bstract
The production cross-sections of
B
mesons are measured in
pp
collisions at a centre-of-mass energy of 7 TeV, using data collected with the LHCb detector corresponding to a integrated ...luminosity of 0.36 fb
−1
. The
B
+
,
B
0
and
$ B_s^0 $
mesons are reconstructed in the exclusive decays
B
+
→
J
/
ψK
+
,
B
0
→
J
/
ψK
*0
and
$ B_s^0\to {J \left/ {{\psi \phi }} \right.} $
, with
J
/
ψ
→
μ
+
μ
−
,
K
*0
→
K
+
π
−
and
ϕ
→
K
+
K
−
. The differential cross-sections are measured as functions of
B
meson transverse momentum
p
T
and rapidity
y
, in the range 0
< p
T
<
40 GeV
/c
and 2
.
0
< y <
4
.
5. The integrated cross-sections in the same
p
T
and
y
ranges, including charge-conjugate states, are measured to be
$ \begin{array}{*{20}{c}} {\sigma \left( {pp\to {B^{+}}+X} \right)=38.9\pm 0.3\left( {\mathrm{stat}.} \right)\pm 2.5\left( {\mathrm{syst}.} \right)\pm 1.3\left( {\mathrm{norm}.} \right)\upmu \mathrm{b},} \hfill \\ {\sigma \left( {pp\to {B^0}+X} \right)=38.1\pm 0.6\left( {\mathrm{stat}.} \right)\pm 3.7\left( {\mathrm{syst}.} \right)\pm 4.7\left( {\mathrm{norm}.} \right)\upmu \mathrm{b},} \hfill \\ {\sigma \left( {pp\to B_s^0+X} \right)=10.5\pm 0.2\left( {\mathrm{stat}.} \right)\pm 0.8\left( {\mathrm{syst}.} \right)\pm 1.0\left( {\mathrm{norm}.} \right)\upmu \mathrm{b},} \hfill \\ \end{array} $
where the third uncertainty arises from the pre-existing branching fraction measurements.
A
bstract
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 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
β
in the Minimal Supersymmetric Model is set in the
$ m_{{{h^0}}}^{\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.
Journal of High Energy Physics 03 (2019) 126 Using $pp$ collisions corresponding to 3$\,\text{fb}^{-1}$ integrated
luminosity, recorded by the LHCb experiment at centre-of-mass energies of 7 and
...8$\,\text{TeV}$, the ratio of branching fractions \begin{align*}
\mathcal{B}(\Lambda^0_b\!\to\psi(2S) \Lambda )/\mathcal{B}(\Lambda^0_b\!\to
J/\psi \Lambda)= 0.513 \pm 0.023\, (\text{stat}) \pm 0.016 \, (\text{syst}) \pm
0.011\, (\mathcal{B}) \end{align*} is determined. The first uncertainty is
statistical, the second is systematic and the third is due to the external
branching fractions used.
Phys. Rev. D 98, 072006 (2018) 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
$B^0 \to \overline{D}^0 \pi^+ \pi^-$ to be $$\frac{\mathcal{B}(B^0 \to
\overline{D}^0 K^+ K^-)}{\mathcal{B}(B^0 \to \overline{D}^0 \pi^+ \pi^-)} =
(6.9 \pm 0.4 \pm 0.3)\%,$$ 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 ${B^0 \to \overline{D}^0 \pi^+ \pi^-}$, 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 ${B^0 \to
\overline{D}^0 \pi^+ \pi^-}$ and $B^0 \to \overline{D}^0 K^+ K^-$,
respectively.
Phys. Rev. D 98, 071103 (2018) The first observation of the $B_s^0 \to \overline{D}^{*0} \phi$ 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 $B^0 \to \overline{D}^0 \pi^+\pi^-$ and is found to
be $\mathcal{B}(B_s^0 \to \overline{D}^{*0} \phi) = (3.7 \pm 0.5 \pm 0.3 \pm
0.2) \times 10^{-5}$, where the first uncertainty is statistical, the second
systematic, and the third from the branching fraction of the $B^0 \to
\overline{D}^0 \pi^+\pi^-$ 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 $B_s^0 \to
\overline{D}^{0} \phi$ decay is also obtained, $\mathcal{B}(B_s^0 \to
\overline{D}^{0} \phi) = (3.0 \pm 0.3 \pm 0.2 \pm 0.2) \times 10^{-5}$. An
upper limit, $\mathcal{B}(B^0 \to \overline{D}^{0} \phi) < 2.0 \ (2.2) \times
10^{-6}$ at $90\%$ (95\%) confidence level is set. A constraint on the
$\omega-\phi$ mixing angle $\delta$ is set at $|\delta| < 5.2^\circ~
(5.5^\circ)$ at $90\%$ ($95\%$) confidence level.
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