Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEvidence for a $B_s^0 pi^pm$ State
86
0
0.0
(
0
)
Authors
D0 Collaboration
Ask ChatGPT about the research
No Arabic abstract
We report evidence of a narrow structure, $X(5568)$, in the decay sequence $X(5568) rightarrow B_s^0 pi^{pm}$, $B_s^0 rightarrow J/psi phi$, $J/psirightarrow mu^+ mu^-$, $phi rightarrow K^+K^-$. This is evidence for the first instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be $m = 5567.8 pm 2.9 {rm thinspace (stat)} ^{+0.9}_{-1.9} {rm thinspace (syst)}$ MeV/$c^2$ and $Gamma = 21.9 pm 6.4 {rm thinspace (stat)} ^{+5.0}_{-2.5} {rm thinspace (syst)} $ MeV/$c^2$. If the decay is $X(5568) rightarrow B_s^* pi^{pm} rightarrow B_s^0 gamma pi^{pm}$ with an unseen $gamma$, $m(X(5568))$ will be shifted up by $m(B_s^*) - m(B_s^0) sim 49$ MeV/$c^2$. This measurement is based on $10.4~rm{fb^{-1}}$ of $p bar p $ collision data at $sqrt{s}$ = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
rate research
Read More
Using 121.4 fb^{-1} of data collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e^+e^- collider, we report evidence for the B_s^0 -> Lambda_c^+ Lambda-bar pi^- decay mode with a measured branching fraction (3.6 +- 1.1[stat.] {+0.3 -0.5}[syst.] +- 0.9[Lambda_c^+] +- 0.7[N_{Bs}]) * 10^{-4} and a significance of 4.4 standard deviations. This is the first evidence for a baryonic B_s^0 decay.
We search for the M1 radiative transition psi(3686) to gammaeta_{c}(2S) by reconstructing the exclusive eta_{c}(2S) to K_{S}^{0}K^{pm}pi^{mp}pi^{+}pi^{-} decay using 1.06 times 10^8 psi(3686) events collected with the BESIII detector. The signal is observed with a statistical significance of greater than 4 standard deviations. The measured mass of the eta_{c}(2S) is 3646.9 pm 1.6(stat) pm 3.6(syst) MeV/c^2, and the width is 9.9 pm 4.8(stat) pm 2.9(syst) MeV/c^2. The product branching fraction is measured to be B(psi(3686) to gammaeta_{c}(2S)) times B(eta_{c}(2S) to K_{S}^{0}K^{pm}pi^{mp}pi^{+}pi^{-}) = (7.03 pm 2.10(stat) pm 0.70(syst)) times 10^{-6}. This measurement complements a previous BESIII measurement of psi(3686) to gammaeta_{c}(2S) with eta_{c}(2S) to K_{S}^{0} K^{pm}pi^{mp} and K^{+}K^{-}pi^{0}.
A search for the rare decays $B_s^0 to pi^+pi^-mu^+mu^-$ and $B^0 to pi^+pi^-mu^+mu^-$ is performed in a data set corresponding to an integrated luminosity of 3.0 fb$^{-1}$ collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3 GeV/$c^2$ and with muon pairs that do not originate from a resonance are considered. The first observation of the decay $B_s^0 to pi^+pi^-mu^+mu^-$ and the first evidence of the decay $B^0 to pi^+pi^-mu^+mu^-$ are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be $mathcal{B}(B_s^0 to pi^+pi^-mu^+mu^-)=(8.6pm 1.5,({rm stat}) pm 0.7,({rm syst})pm 0.7,({rm norm}))times 10^{-8}$ and $mathcal{B}(B^0 to pi^+pi^-mu^+mu^-)=(2.11pm 0.51,({rm stat}) pm 0.15,({rm syst})pm 0.16,({rm norm}) )times 10^{-8}$, where the third uncertainty is due to the branching fraction of the decay $B^0to J/psi(to mu^+mu^-)K^*(890)^0(to K^+pi^-)$, used as a normalisation.
We have studied Bs0 -> Ds- pi+ and Bs0 -> Ds^(-/+) K^(+/-) decays using 23.6 /fb of data collected at the Upsilon(5S) resonance with the Belle detector at the KEKB e+e- collider. This highly pure Bs0 -> Ds- pi+ sample is used to measure the branching fraction, BR(Bs0 -> Ds- pi+)=[3.67 +0.35,-0.33}(stat.) +0.43,-0.42(syst.) +-0.49(f_s)] x 10^{-3} (f_s=N(Bs(*) Bs(*)bar)/N(bbar b)) and the fractions of Bs0 event types at the Upsilon(5S) energy, {in particular N(Bs* Bs*bar}/N(N(Bs(*) Bs(*)bar)=(90.1 +3.8,-4.0 +-0.2)%. We also determine the masses M(Bs0)=(5364.4 +-1.3 +-0.7) MeV/c^2 and M(Bs*)=(5416.4 +-0.4 +-0.5) MeV/c^2. In addition, we observe Bs0 -> Ds^(-/+) K^(+/-) decays with a significance of 3.5sigma and measure BR(Bs0 -> Ds^(-/+) K^(+/-))=[2.4 +1.2,-1.0(stat.) +-0.3(syst.) +-0.3(f_s)] x 10^{-4}.
Using a data sample of 980~fb$^{-1}$ collected with the Belle detector operating at the KEKB asymmetric-energy $e^+e^-$ collider, we present evidence for the $Omega(2012)^-$ in the resonant substructure of $Omega_{c}^{0} to pi^+ (bar{K}Xi)^{-}$ ($(bar{K}Xi)^{-}$ = $K^-Xi^0$ + $bar{K}^0 Xi^-$) decays. The significance of the $Omega(2012)^-$ signal is 4.2$sigma$ after considering the systematic uncertainties. The ratio of the branching fraction of $Omega_{c}^{0} to pi^{+} Omega(2012)^- to pi^+ (bar{K}Xi)^{-}$ relative to that of $Omega_{c}^{0} to pi^{+} Omega^-$ is calculated to be 0.220 $pm$ 0.059(stat.) $pm$ 0.035(syst.). The individual ratios of the branching fractions of the two isospin modes are also determined, and found to be ${cal B}(Omega_{c}^0 to pi^+ Omega(2012)^-) times {cal B}(Omega(2012)^- to K^-Xi^0)/{cal B}(Omega_{c}^0 to pi^+ K^- Xi^0)$ = (9.6 $pm$ 3.2(stat.) $pm$ 1.8(syst.))% and ${cal B}(Omega_{c}^0 to pi^+ Omega(2012)^-) times {cal B}(Omega(2012)^- to bar{K}^0 Xi^-)/{cal B}(Omega_{c}^0 to pi^+ bar{K}^0 Xi^-)$ = (5.5 $pm$ 2.8(stat.) $pm$ 0.7(syst.))%.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
