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Register a new userPhotoproduction of $K^+Lambda(1405) rightarrow K^+pi^0Sigma^0$ extending to forward angles and low momentum transfer
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$K^+Lambda(1405)$ photoproduction has been studied at the BGOOD experiment via the all neutral decay, $Lambda(1405)rightarrowSigma^0pi^0$. BGOODs unique experimental setup allows both the cross section and $Lambda(1405)$ invariant mass distribution (line shape) to be measured over a broad $K^+$ polar angle range, extending to extreme forward $K^+$ angles unattainable at previous experiments. The line shape was determined to be in agreement with the previous results of CLAS and ANKE, and appear consistent with two poles derived in $chi$PT based models. %with hints of a double peak structure which may have been observed in the ANKE results At forward $K^+$ angles the relative strength of the peaks appear to change, however more statistics are required for a firm conclusion. Evidence is provided for the role of a triangle singularity driven by the $N^*(2030)$ resonance, which appears to significantly contribute to $K^+Lambda(1405)$ photoproduction. This is observed in both the angular distributions and the integrated cross section which was determined with unprecedented energy resolution.
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$gamma p rightarrow K^+ Lambda$ differential cross sections and recoil polarisation data from threshold for extremely forward angles are presented. The measurements were performed at the BGOOD experiment at ELSA, utilising the high angular and momentum resolution forward spectrometer for charged particle identification. The data discriminates between conflicting results in the world data set and enable extraction of the cross section as the minimum momentum transfer to the recoiling hyperon is approached.
The $gamma p rightarrow K^+Sigma^0$ differential cross section at extremely forward angles was measured at the BGOOD experiment. A three-quarter drop in strength over a narrow range in energy and a strong dependence on the polar angle of the $K^+$ in the centre-of-mass of the reaction is observed at a centre-of-mass energy of 1900,MeV. Residing close to multiple open and hidden strangeness thresholds, the structure appears consistent with meson-baryon threshold effects which may contribute to the reaction mechanism.
Since the discovery of the $Lambda(1405)$, it remains poorly described by conventional constituent quark models, and it is a candidate for having an exotic meson-baryon or penta-quark structure, similar to states recently reported in the hidden charm sector. The $Lambda(1405)$ can be produced in the reaction $gamma p rightarrow K^+Lambda(1405)$. The pure I=0 decay mode into $Sigma^0pi^0$ is prohibited for the mass-overlapping $Sigma(1385)$. Combining a large aperture forward magnetic spectrometer and a central BGO crystal calorimeter, the BGO-OD experiment is ideally suited to measure this decay with the $K^+$ in the forward direction. Preliminary results are presented. *Supported by DFG (PN 388979758, 405882627).
We investigate the photoproduction of $K^*$ vector meson for the study of the $Lambda(1405)$ resonance. The invariant mass distribution of $piSigma$ shows a different shape from the nominal one, peaking at 1420 MeV. This is considered as a consequence of the double pole structure of $Lambda(1405)$, predicted in the chiral unitary model. Combined with other reactions, such as $pi^- p to K^0 piSigma$, experimental confirmation of this fact will reveal a novel structure of the $Lambda(1405)$ state.
Measurements of the effective lifetimes in the $B_{s}^{0} rightarrow K^{+}K^{-}$, $B^{0} rightarrow K^{+}pi^{-}$ and $B_{s}^{0} rightarrow pi^{+}K^{-}$ decays are presented using $1.0~mathrm{fb^{-1}}$ of $pp$ collision data collected at a centre-of-mass energy of 7 TeV by the LHCb experiment. The analysis uses a data-driven approach to correct for the decay time acceptance. The measured effective lifetimes are $tau_{B_{s}^{0} rightarrow K^{+}K^{-}}$ = $1.407~pm~0.016~pm~0.007~mathrm{ps}$, $tau_{B^{0} rightarrow K^{+}pi^{-}}$ = $1.524~pm~0.011~pm~0.004~mathrm{ps}$, $tau_{B_{s}^{0} rightarrow pi^{+}K^{-}}$ = $1.60~pm~0.06~pm~0.01~mathrm{ps}$. This is the most precise determination to date of the effective lifetime in the $B_{s}^{0} rightarrow K^{+}K^{-}$ decay and provides constraints on contributions from physics beyond the Standard Model to the $B_{s}^{0}$ mixing phase and the width difference $DeltaGamma_{s}$.
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