The negative-parity spin-1/2 Λ baryon spectrum from lattice QCD and effective theory

The spectrum of the negative-parity spin-1/2 $\Lambda$ baryons is studied using lattice QCD and hadronic effective theory in a unitarized coupled-channel framework. A direct comparison between the two approaches is possible by considering the hadronic effective theory in a finite volume and with hadron masses and mesonic decay constants that correspond to the situation studied on the lattice. Comparing the energy level spectrum and $SU(3)$ flavor decompositions of the individual states, it is found that the lowest two states extracted from lattice QCD can be identified with one of the two $\Lambda(1405)$-poles and the $\Lambda(1670)$ resonance. The quark mass dependences of these two lattic…

Study of the possible role of triangle singularities in ${B^ - }\, \to {D^{*0}}{\pi ^ - }{\pi ^0}\eta $ and ${B^ - }\, \to {D^{*0}}{\pi ^ - }{\pi ^ + }{\pi ^ - }$

Studying the effects of triangle singularities in hadronic processes is of the utmost importance since they can originate peaks that may wrongfully be associated with resonances. In this work, the role of the triangle mechanism in the decays and is explored. Here, the singularity appears when B- decays into , K *0 decays into K + through pion emission, and K - K + fuse together forming either the a 0 (980) or f 0 (980) which then decays into π 0 η or π+ π – , respectively. As a result, the K * K + K - loop generates a peak in the invariant mass of π - a 0 or π - f 0 around 1420 MeV. The branching ratios that come from this peak are and , which are well within the measurable range. Thus, thi…

The first observation of narrow peak and isospin-violating Λ(1405) production

Anomalous enhancement of the isospin-violating Λ(1405) production by a triangle singularity in Λc→π+π0π0Σ0

The decay of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ into ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{0}\mathrm{\ensuremath{\Lambda}}(1405)$ with the $\mathrm{\ensuremath{\Lambda}}(1405)$ decay into ${\ensuremath{\pi}}^{0}{\mathrm{\ensuremath{\Sigma}}}^{0}$ through a triangle diagram is studied. This process is initiated by ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\overline{K}}^{*}N$, and then the ${\overline{K}}^{*}$ decays into $\overline{K}\ensuremath{\pi}$ and $\overline{K}N$ produce the $\mathrm{\ensuremath{\Lambda}}(1405)$ through a triangle loop containing ${\overline{K}}^{*}N\overline{K}$ which develops a singularity around 1890 MeV. Th…

A novel approach on τ lepton decay and its application to polarization amplitudes

Production of N*(1535) and N*(1650) in Λc→K¯0ηp(πN) decay

To study the properties of the ${N}^{*}$(1535) and ${N}^{*}$(1650), we calculate the mass distributions of $MB$ in the ${\mathrm{\ensuremath{\Lambda}}}_{c}\ensuremath{\rightarrow}{\overline{K}}^{0}MB$ decay, with $MB=\ensuremath{\pi}N(I=1/2),\phantom{\rule{0.28em}{0ex}}\ensuremath{\eta}p$, and $K\mathrm{\ensuremath{\Sigma}}(I=1/2)$. We do this by calculating the tree-level and loop contributions, mixing pseudoscalar-baryon and vector-baryon channels using the local hidden gauge formalism. The loop contributions for each channel are calculated using the chiral unitary approach. We observe that for the $\ensuremath{\eta}N$ mass distribution only the ${N}^{*}$(1535) is seen, with the ${N}^{*}$…