اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMeasurement of $C!P$ asymmetries in two-body $B_{(s)}^{0}$-meson decays to charged pions and kaons
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The time-dependent $C!P$ asymmetries in $B^0topi^+pi^-$ and $B_s^0to K^+!K^-$ decays are measured using a data sample of $pp$ collisions corresponding to an integrated luminosity of 3.0 fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated $C!P$ asymmetries in $B^0to K^+pi^-$ and $B_s^0topi^+ K^-$ decays. The results are $C_{pi^+pi^-} = -0.34 pm 0.06 pm 0.01$, $S_{pi^+pi^-} = -0.63 pm 0.05 pm 0.01$, $C_{K^+!K^-} = 0.20 pm 0.06 pm 0.02$, $S_{K^+!K^-} = 0.18 pm 0.06 pm 0.02$, $C_{K^+!K^-}^{DeltaGamma} = -0.79 pm 0.07 pm 0.10$, $A_{C!P}^{B^0} = -0.084 pm 0.004 pm 0.003$, and $A_{C!P}^{B_s^0} = 0.213 pm 0.015 pm 0.007$, where the first uncertainties are statistical and the second systematic. Evidence for $C!P$ violation is found in the $B_s^0to K^+!K^-$ decay for the first time.
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The time-dependent $CP$ asymmetries of $B^0to pi^+pi^-$ and $B^0_mathrm{s}!to K^+K^-$ decays are measured using a data sample of $pp$ collisions corresponding to an integrated luminosity of 1.9 fb$^{-1}$, collected with the LHCb detector at a centre-
of-mass energy of 13 TeV. The results are begin{eqnarray*} C_{pipi} & = & -0.311 pm 0.045 pm 0.015, S_{pipi} & = & -0.706 pm 0.042 pm 0.013, C_{KK} & = & phantom{-}0.164 pm 0.034 pm 0.014, S_{KK} & = & phantom{-}0.123 pm 0.034 pm 0.015, cal {A}^{mathrm{DeltaGamma}}_{mathit{KK}} & = & -0.83phantom{0} pm 0.05phantom{0} pm 0.09, end{eqnarray*} where the first uncertainties are statistical and the second systematic. The same data sample is used to measure the time-integrated $CP$ asymmetries of $B^0to K^+pi^-$ and $B^0_mathrm{s}to K^-pi^+$ decays and the results are begin{eqnarray*} A_{CP}^{B^0} & = & -0.0824 pm 0.0033 pm 0.0033, A_{CP}^{B^0_mathrm{s}} & = & phantom{-}0.236phantom{0} pm 0.013phantom{0} pm 0.011. end{eqnarray*} All results are consistent with earlier measurements. A combination of LHCb measurements provides the first observation of time-dependent $CP$ violation in $B^0_mathrm{s}$ decays.
CP asymmetries have been measured recently by the LHCb collaboration in three-body $B^+$ decays to final states involving charged pions and kaons. Large asymmetries with opposite signs at a level of about 60% have been observed in $B^pmto pi^pm({rm o
r} K^pm)pi^+pi^-$ and $B^pm to pi^pm K^+K^-$ for restricted regions in the Dalitz plots involving $pi^+pi^-$ and $K^+K^-$ with low invariant mass. U-spin is shown to predict corresponding $Delta S=0$ and $Delta S=1$ asymmetries with opposite signs and inversely proportional to their branching ratios, in analogy with a successful relation predicted thirteen years ago between asymmetries in $B_sto K^-pi^+$ and $B^0 to K^+ pi^-$. We compare these predictions with the measured integrated asymmetries. Effects of specific resonant or non-resonant partial waves on enhanced asymmetries for low-pair-mass regions of the Dalitz plot are studied in $B^pm to pi^pm pi^+pi^-$. The closure of low-mass $pi^+pi^-$ and $K^+K^-$ channels involving only $pipi leftrightarrow Kbar K$ rescattering may explain by CPT approximately equal magnitudes and opposite signs measured in $B^pmto pi^pmpi^+pi^-$ and $B^pm to pi^pm K^+K^-$.
Measurements of $C!P$ observables in $B^0 to DK^{*0}$ decays are presented, where $D$ represents a superposition of $D^0$ and $bar{D}^0$ states. The $D$ meson is reconstructed in the two-body final states $K^+pi^-$, $pi^+ K^-$, $K^+K^-$ and $pi^+pi^-
$, and, for the first time, in the four-body final states $K^+pi^-pi^+pi^-$, $pi^+ K^-pi^+pi^-$ and $pi^+pi^-pi^+pi^-$. The analysis uses a sample of neutral $B$ mesons produced in proton-proton collisions, corresponding to an integrated luminosity of 1.0, 2.0 and 1.8 $rm fb^{-1}$ collected with the LHCb detector at centre-of-mass energies of $sqrt{s} = $ 7, 8 and 13 TeV, respectively. First observations of the decays $B^0 to D(pi^+ K^-)K^{*0}$ and $B^0 to D(pi^+pi^-pi^+pi^-)K^{*0}$ are obtained. The measured observables are interpreted in terms of the $C!P$-violating weak phase $gamma$.
A study of $B^{0}_{s} to eta_{c} phi$ and $B^{0}_{s} to eta_{c} pi^{+}pi^{-}$ decays is performed using $pp$ collision data corresponding to an integrated luminosity of 3.0$,rm fb^{-1}$, collected with the LHCb detector in Run~1 of the LHC. The obser
vation of the decay $B^{0}_{s} to eta_{c} phi$ is reported, where the $eta_{c}$ meson is reconstructed in the $pbar p$, $K^+K^-pi^+pi^-$, $pi^+pi^-pi^+pi^-$ and $K^+K^-K^+K^-$ decay modes and the $phi(1020)$ in the $K^+ K^-$ decay mode. The decay $B^{0}_{s} to J/psi phi$ is used as a normalisation channel. Evidence is also reported for the decay $B^{0}_{s} to eta_{c} pi^{+}pi^{-}$, where the $eta_{c}$ meson is reconstructed in the $pbar p$ decay mode, using the decay $B^{0}_{s} to J/psi pi^+ pi^-$ as a normalisation channel. The measured branching fractions are begin{eqnarray*} {mathcal B (B^{0}_{s} to eta_{c} phi)} &=& left(5.01 pm 0.53 pm 0.27 pm 0.63 right) times 10^{-4} ,, onumber {mathcal B (B^{0}_{s} to eta_{c} pi^+ pi^-)} &=& left(1.76 pm 0.59 pm 0.12 pm 0.29 right) times 10^{-4} ,, end{eqnarray*} where in each case the first uncertainty is statistical, the second systematic and the third uncertainty is due to the limited knowledge of the external branching fractions.
A search for charmless three-body decays of $B^0$ and $B_{s}^0$ mesons with a $K_{rm S}^0$ meson in the final state is performed using the $pp$ collision data, corresponding to an integrated luminosity of $1.0,mbox{fb}^{-1}$, collected at a centre-of
-mass energy of $7mathrm{,Tekern -0.1em V}$ recorded by the LHCb experiment. Branching fractions of the $B_{(s)}^0 to K_{rm S}^0 h^{+} h^{prime -}$ decay modes ($h^{(prime)} = pi, K$), relative to the well measured $B^0 to K_{rm S}^0 pi^{+} pi^{-}$ decay, are obtained. First observation of the decay modes $B_s^0 to K_{rm S}^0 K^{pm} pi^{mp}$ and $B_s^0 to K_{rm S}^0 pi^{+} pi^{-}$ and confirmation of the decay $B^0 to K_{rm S}^0 K^{pm} pi^{mp}$ are reported. The following relative branching fraction measurements or limits are obtained begin{eqnarray*} onumber frac{{cal B}(B^0 to K_{rm S}^0 K^{pm} pi^{mp})}{{cal B}(B^0 to K_{rm S}^0 pi^{+} pi^{-})} &=& 0.128 pm 0.017 , ({rm stat.}) pm 0.009 , ({rm syst.}) ,, onumber frac{{cal B}(B^0 to K_{rm S}^0 K^{+} K^{-} )}{{cal B}(B^0 to K_{rm S}^0 pi^{+} pi^{-})} &=& 0.385 pm 0.031 , ({rm stat.}) pm 0.023 , ({rm syst.}) ,, onumber frac{{cal B}(B_s^0 to K_{rm S}^0 pi^{+} pi^{-} )}{{cal B}(B^0 to K_{rm S}^0 pi^{+} pi^{-})} &=& 0.29phantom{0} pm 0.06phantom{0} , ({rm stat.}) pm 0.03phantom{0} , ({rm syst.}) pm 0.02 , (f_s/f_d) ,, onumber frac{{cal B}(B_s^0 to K_{rm S}^0 K^{pm} pi^{mp})}{{cal B}(B^0 to K_{rm S}^0 pi^{+} pi^{-})} &=& 1.48phantom{0} pm 0.12phantom{0} , ({rm stat.}) pm 0.08phantom{0} , ({rm syst.}) pm 0.12 , (f_s/f_d) ,, onumber frac{{cal B}(B_s^0 to K_{rm S}^0 K^{+} K^{-} )}{{cal B}(B^0 to K_{rm S}^0 pi^{+} pi^{-})} &in& [0.004;0.068] ; {rm at ;; 90% ; CL} ,. end{eqnarray*}
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