Using data accumulated by DELPHI during the November 1995 LEP run at 130-136 GeV, searches have been made for events with jets or leptons in conjunction with missing momentum, The results are ...interpreted in terms of limits on the production of neutralinos
JHEP 12 (2016) 087 A combination of measurements sensitive to the CKM angle $\gamma$ from LHCb
is performed. The inputs are from analyses of time-integrated $B^{+}\rightarrow
DK^+$, $B^{0} ...\rightarrow D K^{*0}$, $B^{0} \rightarrow D K^+ \pi^-$ and $B^{+}
\rightarrow D K^+\pi^+\pi^-$ tree-level decays. In addition, results from a
time-dependent analysis of $B_{s}^{0} \rightarrow D_{s}^{\mp}K^{\pm}$ decays
are included. The combination yields $\gamma = (72.2^{+6.8}_{-7.3})^\circ$,
where the uncertainty includes systematic effects. The 95.5% confidence level
interval is determined to be $\gamma \in 55.9,85.2^\circ$. A second
combination is investigated, also including measurements from $B^{+}
\rightarrow D \pi^+$ and $B^{+} \rightarrow D \pi^+\pi^-\pi^+$ decays, which
yields compatible results.
A search for pair-production of neutralinos at a LEP centre-of-mass energy of 189 GeV gave no evidence for a signal. This limits the neutralino production cross-section and excludes regions in the ...parameter space of the Minimal Supersymmetric Standard Model (MSSM).
J. High Energ. Phys. (2017) 2017: 30 An amplitude analysis of the decay $\Lambda_b^0\to D^0 p \pi^-$ is performed
in the part of the phase space containing resonances in the $D^0 p$ channel.
The ...study is based on a data sample corresponding to an integrated luminosity
of 3.0 fb$^{-1}$ of $pp$ collisions recorded by the LHCb experiment. The
spectrum of excited $\Lambda_c^+$ states that decay into $D^0 p$ is studied.
The masses, widths and quantum numbers of the $\Lambda_c(2880)^+$ and
$\Lambda_c(2940)^+$ resonances are measured. The constraints on the spin and
parity for the $\Lambda_c(2940)^+$ state are obtained for the first time. A
near-threshold enhancement in the $D^0 p$ amplitude is investigated and found
to be consistent with a new resonance, denoted the $\Lambda_c(2860)^+$, of spin
$3/2$ and positive parity.
Phys. Lett. B 767 (2017), 177-187 A measurement of the time-integrated $CP$ asymmetry in the Cabibbo-suppressed
decay $D^0\rightarrow K^-K^+$ is performed using pp collision data,
corresponding to an ...integrated luminosity of 3fb$^{-1}$, collected with the
LHCb detector at centre-of-mass energies of 7 and 8 TeV. The flavour of the
charm meson at production is determined from the charge of the pion in
$D^{*+}\rightarrow D^0 \pi^+$ and $D^{*-}\rightarrow \bar{D^0} \pi^-$ decays.
The time-integrated $CP$ asymmetry $A_{CP}(K^-K^+)$ is obtained assuming
negligible $CP$ violation in charm mixing and in Cabibbo-favoured
$D^0\rightarrow K^-\pi^+$, $D^+\rightarrow K^-\pi^+\pi^+$ and $D^+\rightarrow
\bar{K^0}\pi^+$ decays used as calibration channels. It is found to be
$A_{CP}(K^-K^+)=(0.14\pm0.15(stat)\pm0.10(syst))\%$. A combination of this
result with previous LHCb measurements yields
$A_{CP}(K^-K^+)=(0.04\pm0.12(stat)\pm0.10(syst))\%$,
$A_{CP}(\pi^-\pi^+)=(0.07\pm0.14(stat)\pm0.11(syst))\%$. These are the most
precise measurements from a single experiment. The result for $A_{CP}(K^-K^+)$
is the most precise determination of a time-integrated $CP$ asymmetry in the
charm sector to date, and neither measurement shows evidence of CP asymmetry.
Phys. Rev. D 95, 052005 (2017) The $B^{\pm}$ meson production asymmetry in $pp$ collisions is measured using
$B^+ \to \bar{D}^0 \pi^+$ decays. The data were recorded by the LHCb experiment
during Run ...1 of the LHC at centre-of-mass energies of $\sqrt{s}=$ 7 and 8 TeV.
The production asymmetries, integrated over transverse momenta in the range $2
< p_{\rm T} < 30$ GeV/$c$, and rapidities in the range $2.1 < y < 4.5$, are
measured to be
\begin{align*} \mathcal{A}_{\rm prod}(B^+,\sqrt{s}=7~{\rm TeV}) &= (-0.41 \pm
0.49 \pm 0.10) \times 10^{-2},\\ \mathcal{A}_{\rm prod}(B^+,\sqrt{s}=8~{\rm
TeV}) &= (-0.53 \pm 0.31 \pm 0.10) \times 10^{-2},
\end{align*} where the first uncertainties are statistical and the second are
systematic. These production asymmetries are used to correct the raw
asymmetries of $B^{+} \to J/\psi K^{+}$ decays, thus allowing a measurement of
the $CP$ asymmetry, \begin{equation*}
\mathcal{A}_{CP} = (0.09 \pm 0.27 \pm 0.07) \times 10^{-2}.
\end{equation*}
Phys. Rev. Lett. 118, 081801 (2017) A search for the $B^{0}\to K^{+}K^{-}$ decay is performed using
$pp$-collision data collected by LHCb. The data set corresponds to integrated
luminosities of 1 and ...2 fb$^{-1}$ at center-of-mass energies of 7 and 8 TeV,
respectively. This decay is observed for the first time, with a significance of
more than five standard deviations. The analysis also results in an improved
measurement of the branching fraction for the $B_s^0\to \pi^+\pi^-$ decay. The
measured branching fractions are $BR(B^0\to K^+K^-) = (7.80 \pm 1.27 \pm 0.81
\pm 0.21) \times 10^{-8}$ and $BR(B_s^0\to\pi^+\pi^-) = (6.91 \pm 0.54 \pm 0.63
\pm 0.19 \pm 0.40) \times 10^{-7}$. The first uncertainty is statistical, the
second is systematic, the third is due to the uncertainty on the $B^0\to
K^+\pi^-$ branching fraction used as a normalization. For the $B_s^0$ mode, the
fourth accounts for the uncertainty on the ratio of the probabilities for $b$
quarks to hadronize into $B_s^0$ and $B^0$ mesons.
Phys. Lett. B 772 (2017) 265-273 The observation of the decay $\varXi^{-}_{b}\to J/\psi\varLambda K^{-}$ is
reported, using a data sample corresponding to an integrated luminosity of
...$3~\mathrm{fb}^{-1}$, collected by the LHCb detector in $pp$ collisions at
centre-of-mass energies of $7$ and $8~\mathrm{TeV}$. The production rate of
$\varXi_{b}^{-}$ baryons detected in the decay $\varXi_{b}^{-}\to
J/\psi\varLambda K^{-}$ is measured relative to that of $\varLambda_{b}^{0}$
baryons using the decay $\varLambda_{b}^{0}\to J/\psi \varLambda$. Integrated
over the $b$-baryon transverse momentum $p_{\rm T}<25~\mathrm{GeV/}c $ and
rapidity $2.0<y<4.5$, the measured ratio is \begin{equation*}
\frac{f_{\varXi_{b}^{-}}}{f_{\varLambda_{b}^{0}}}\frac{\mathcal{B}(\varXi_{b}^{-}\to
J/\psi\varLambda K^{-})}{\mathcal{B}(\varLambda_{b}^{0}\to J/\psi
\varLambda)}=(4.19\pm 0.29~(\mathrm{stat})\pm0.15~(\mathrm{syst}))\times
10^{-2}, \end{equation*}where $f_{\varXi_{b}^{-}}$ and $f_{\varLambda_{b}^{0}}$
are the fragmentation fractions of $b\to\varXi_{b}^{-}$ and
$b\to\varLambda_{b}^{0}$ transitions, and $\mathcal{B}$ represents the
branching fraction of the corresponding $b$-baryon decay. The mass difference
between $\varXi_{b}^{-}$ and $\varLambda_{b}^{0}$ baryons is measured to be
\begin{equation*}
M(\varXi_{b}^{-})-M(\varLambda_{b}^{0})=177.08\pm0.47~(\mathrm{stat})\pm0.16~(\mathrm{syst}
)~\mathrm{MeV/}c^{2}. \end{equation*}
Phys. Rev. D 95, 012006 (2017) The first observation of the rare decay$B^0_s \to \phi\pi^+\pi^-$ and
evidence for $B^0 \to \phi\pi^+\pi^-$ are reported, using $pp$ collision data
recorded by the LHCb ...detector at centre-of-mass energies $\sqrt{s} = 7$ and
8~TeV, corresponding to an integrated luminosity of $3{\mbox{\,fb}^{-1}}$. The
branching fractions in the $\pi^+\pi^-$ invariant mass range
$400<m(\pi^+\pi^-)<1600{\mathrm{\,Me\kern -0.1em V\!/}c^2}$ are $3.48\pm
0.23\pm 0.17\pm 0.35\times 10^{-6}$ and $1.82\pm 0.25\pm 0.41\pm 0.14\times
10^{-7}$ for $B^0_s \to \phi\pi^+\pi^-$ and $B^0 \to \phi\pi^+\pi^-$
respectively, where the uncertainties are statistical, systematic and from the
normalisation mode $B^0_s \to \phi\phi $. A combined analysis of the
$\pi^+\pi^-$ mass spectrum and the decay angles of the final-state particles
identifies the exclusive decays $B^0_s \to \phi f_0(980) $, $B_s^0 \to \phi
f_2(1270) $, and $B^0_s \to \phi\rho^0$ with branching fractions of $1.12\pm
0.16^{+0.09}_{-0.08}\pm 0.11\times 10^{-6}$, $0.61\pm 0.13^{+0.12}_{-0.05}\pm
0.06\times 10^{-6}$ and $2.7\pm 0.7\pm 0.2\pm 0.2\times 10^{-7}$,
respectively.
Phys. Rev. Lett. 118, 111803 (2017) Using proton-proton collision data corresponding to an integrated luminosity
of 3.0 fb$^{-1}$, recorded by the LHCb detector at centre-of-mass energies of 7
and 8 ...TeV, the $B_{c}^{+} \rightarrow D^{0} K^{+}$ decay is observed with a
statistical significance of 5.1 standard deviations.
By normalising to $B^{+} \rightarrow \bar{D}^{0} \pi^{+}$ decays, a
measurement of the branching fraction multiplied by the production rates for
$B_{c}^{+}$ relative to $B^{+}$ mesons in the LHCb acceptance is obtained, $$
R_{D^{0} K} = \frac{f_{c}}{f_{u}}\times\mathcal{B}(B_{c}^{+} \rightarrow D^{0}
K^{+}) = (9.3\,^{+2.8}_{-2.5} \pm 0.6) \times 10^{-7}\,, $$ where the first
uncertainty is statistical and the second is systematic. This decay is expected
to proceed predominantly through weak annihilation and penguin amplitudes, and
is the first $B_{c}^{+}$ decay of this nature to be observed.
PDF
