A search for the lepton-flavour violating decays \(B^+ \to K^+ {\mu}^{\pm} e^{\mp}\) is performed using a sample of proton-proton collision data, collected with the LHCb experiment at centre-of-mass ...energies of \(7\) and \(8~{\rm TeV}\) and corresponding to an integrated luminosity of 3\(\rm~fb^{-1}\). No significant signal is observed, and upper limits on the branching fractions are set as \(\mathcal{B}(B^+ \to K^+ {\mu}^- e^+) < 7.0~(9.5) \times 10^{-9}\) and \(\mathcal{B}(B^+ \to K^+ {\mu}^+ e^-) < 6.4~(8.8) \times 10^{-9}\) at 90 (95) % confidence level. The results improve the current best limits on these decays by more than one order of magnitude.
The first observation of the Lambda(0)(b) -> D-s(-) p decay is presented using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of root s = 13TeV, ...corresponding to a total integrated luminosity of 6 fb(-1). Using the Lambda(0)(b) -> Lambda(+pi-)(c) decay as the normalisation mode, the branching fraction of the Lambda(0)(b) -> D-s(-) p decay is measured to be B (Lambda(0)(b) -> D-s(-) p) = (12.6 +/- 0.5 +/- 0.3 +/- 1.2) x 10(-6), where the first uncertainty is statistical, the second systematic and the third due to uncertainties in the branching fractions of the Lambda(0)(b) -> Lambda(+pi-)(c), D-s(-) -> K-K+pi(-) and Lambda(+)(c) -> pK(-)pi(+) decays.
A
bstract
The inclusive
$$ b\overline{b} $$
b
b
¯
- and
$$ c\overline{c} $$
c
c
¯
-dijet production cross-sections in the forward region of
pp
collisions are measured using a data sample collected ...with the LHCb detector at a centre-of-mass energy of 13 TeV in 2016. The data sample corresponds to an integrated luminosity of 1.6 fb
−
1
. Differential cross-sections are measured as a function of the transverse momentum and of the pseudorapidity of the leading jet, of the rapidity difference between the jets, and of the dijet invariant mass. A fiducial region for the measurement is defined by requiring that the two jets originating from the two
b
or
c
quarks are emitted with transverse momentum greater than 20 GeV/
c
, pseudorapidity in the range 2
.
2
< η <
4
.
2, and with a difference in the azimuthal angle between the two jets greater than 1.5. The integrated
$$ b\overline{b} $$
b
b
¯
-dijet cross-section is measured to be 53
.
0 ± 9
.
7 nb, and the total
$$ c\overline{c} $$
c
c
¯
-dijet cross-section is measured to be 73 ± 16 nb. The ratio between
$$ c\overline{c} $$
c
c
¯
- and
$$ b\overline{b} $$
b
b
¯
-dijet cross-sections is also measured and found to be 1
.
37 ± 0
.
27. The results are in agreement with theoretical predictions at next-to-leading order.
Abstract
A first search for
$$CP$$
CP
violation in the Cabibbo-suppressed
$${{{\varXi }} ^+_{c}} \rightarrow {p} {{K} ^-} {{\pi } ^+} $$
Ξ
c
+
→
p
K
-
π
+
decay is performed using both a binned and ...an unbinned model-independent technique in the Dalitz plot. The studies are based on a sample of proton-proton collision data, corresponding to an integrated luminosity of
$$3.0\,\text {fb} ^{-1} $$
3.0
fb
-
1
, and collected by the LHCb experiment at centre-of-mass energies of 7 and
$$8\,\text {TeV} $$
8
TeV
. The data are consistent with the hypothesis of no
$$CP$$
CP
violation.
The ratio of branching fractions of the decays \( {\Lambda}_b^0 \) → pK-e+e- and \( {\Lambda}_b^0 \) → pK-μ+μ-, \( {R}_{pK}^{-1} \) , is measured for the first time using proton-proton collision data ...corresponding to an integrated luminosity of 4.7 fb-1 recorded with the LHCb experiment at center-of-mass energies of 7, 8 and 13 TeV. In the dilepton mass-squared range 0.1 < q2< 6.0 GeV2/c4 and the pK- mass range m(pK-) < 2600 MeV/c2, the ratio of branching fractions is measured to be \( {R}_{pK}^{-1}={1.17}_{-0.16}^{+0.18}\pm 0.07 \) , where the first uncertainty is statistical and the second systematic. This is the first test of lepton universality with b baryons and the first observation of the decay \( {\Lambda}_b^0 \) → pK-e+e-.
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