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Register a new userObservation of new resonances in the $Lambda_{b}^0pi^+pi^-$ system
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We report the observation of a new structure in the $Lambda_b^0 pi^+pi^-$ spectrum using the full LHCb data set of $pp$ collisions, corresponding to an integrated luminosity of $9,mathrm{fb}^{-1}$, collected at $sqrt{s}=7$, 8 and $13,mathrm{TeV}$. A study of the structure suggests its interpretation as a superposition of two almost degenerate narrow states. The masses and widths of these states are measured to be begin{eqnarray*} m_{Lambda_{b}mathrm{(6146)}^0} &=&6146.17 pm 0.33 pm 0.22 pm 0.16,mathrm{MeV} ,, m_{Lambda_{b}mathrm{(6152)}^0} &=&6152.51 pm 0.26 pm 0.22 pm 0.16,mathrm{MeV} ,, Gamma_{Lambda_{b}mathrm{(6146)}^0}&=&phantom{615}2.9phantom{0}pm 1.3phantom{0} pm 0.3phantom{0},mathrm{MeV},, Gamma_{Lambda_{b}mathrm{(6152)}^0} &=&phantom{615}2.1phantom{0}pm 0.8phantom{0} pm 0.3phantom{0},mathrm{MeV},, end{eqnarray*} with a mass splitting of $Delta m = 6.34 pm 0.32 pm 0.02,mathrm{MeV}$, where the first uncertainty is statistical, the second systematic and the third derives from the knowledge of the mass of the $Lambda_b^0$ baryon. The measured masses and widths of these new excited states suggest their possible interpretation as a doublet of $Lambda_{b}mathrm{(1D)}^0$ states.
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A new baryon state is observed in the $Lambda_b^0pi^+pi^-$ mass spectrum with high significance using a data sample of $pp$ collisions, collected with the LHCb detector at centre-of-mass energies $sqrt{s}=7, 8$ and 13TeV, corresponding to an integrated luminosity of 9fb$^{-1}$. The mass and natural width of the new state are measured to be begin{eqnarray*} m & = & 6072.3 pm 2.9 pm 0.6 pm 0.2 MeV,, Gamma & = & 72 pm 11 pm 2 MeV,, end{eqnarray*} where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the $Lambda_b^0$ baryon mass. The new state is consistent with the first radial excitation of the $Lambda_b^0$ baryon, the $Lambda_b(2S)^0$ resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed $Lambda_b(5912)^0$ and $Lambda_b(5920)^0$ states are also reported.
The radiative decay $Lambda_{b}^{0} to Lambda gamma$ is observed for the first time using a data sample of proton-proton collisions corresponding to an integrated luminosity of $1.7,fb^{-1}$ collected by the LHCb experiment at a center-of-mass energy of $13,TeV$. Its branching fraction is measured exploiting the $B^{0} to K^{*0} gamma$ decay as a normalization mode and is found to be $mathcal{B}(Lambda_{b}^{0} to Lambda gamma)= (7.1 pm 1.5 pm 0.6 pm 0.7) times 10^{-6}$, where the quoted uncertainties are statistical, systematic and systematic from external inputs, respectively. This is the first observation of a radiative decay of a beauty baryon.
The X(3872) and Y(3940) properties and decay modes from Belle are reviewed and the results on a search for the decay $B^+ra h_c K^+$, $h_cra eta_c gamma$ at Belle are presented.
The ratios of the branching fractions of the decays $Lambda_{c}^{+} rightarrow p pi^{-} pi^{+}$, $Lambda_{c}^{+} rightarrow p K^{-} K^{+}$, and $Lambda_{c}^{+} rightarrow p pi^{-} K^{+}$ with respect to the Cabibbo-favoured $Lambda_{c}^{+} rightarrow p K^{-} pi^{+}$ decay are measured using proton-proton collision data collected with the LHCb experiment at a 7 TeV centre-of-mass energy and corresponding to an integrated luminosity of 1.0 fb$^{-1}$: begin{align*} frac{mathcal{B}(Lambda_{c}^{+} rightarrow p pi^{-} pi^{+})}{mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} pi^{+})} & = (7.44 pm 0.08 pm 0.18),%, frac{mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} K^{+})}{mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} pi^{+})} &= (1.70 pm 0.03 pm 0.03),%, frac{mathcal{B}(Lambda_{c}^{+} rightarrow p pi^{-} K^{+})}{mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} pi^{+})} & = (0.165 pm 0.015 pm 0.005 ),%, end{align*} where the uncertainties are statistical and systematic, respectively. These results are the most precise measurements of these quantities to date. When multiplied by the world-average value for $mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} pi^{+})$, the corresponding branching fractions are begin{align*} mathcal{B}(Lambda_{c}^{+} rightarrow p pi^{-} pi^{+}) &= (4.72 pm 0.05 pm 0.11 pm 0.25) times 10^{-3}, mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} K^{+}) &= (1.08 pm 0.02 pm 0.02 pm 0.06) times 10^{-3}, mathcal{B}(Lambda_{c}^{+} rightarrow p pi^{-} K^{+}) &= (1.04 pm 0.09 pm 0.03 pm 0.05) times 10^{-4}, end{align*} where the final uncertainty is due to $mathcal{B}(Lambda_{c}^{+} rightarrow p K^{-} pi^{+})$.
A partial wave analysis of the of the $pi ^0pi ^0$ system produced in the charge exchange reaction: $pi ^-pto pi ^0pi ^0n$ at an incident momentum of $18.3 GeV/c$ is presented as a function of ${pi ^0pi ^0}$ invariant mass, $m_{pi^0pi^0}$, and momentum transfer squared, $| {t} |$, from the incident $pi^-$ to the outgoing ${pi ^0pi ^0}$ system.
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