Yangian description for decays and possible explanation of XX in the decay KL0→π0π0XK^0_L\to \pi^0 \pi^0 X

In this letter, hadronic decay channels of light pseudoscalar mesons are realized in Yangian algebra. In the framework of Yangian, we find that these decay channels can be formulated by acting transition operators, composed of the generators of Yangian, on the corresponding pseudoscalar mesons. This new description of decays allows us to present a possible interpretation of the new unknown particle $X$ in the decay $K^0_L\to \pi^0 \pi^0 X$: it is an entangled state of $\pi^0$ and $\eta$

Semileptonic and non-leptonic B_c decays

We make predictions for the exclusive semileptonic and the non-leptonic decay widths of the B_c meson. We evaluate the B_c semileptonic form factors for different decay channels in a relativistic model, and use factorization to obtain the non-leptonic decay widths.Comment: 11 Pages, 1 Postscript figur

Quantum Emitters near Layered Plasmonic Nanostructures: Decay Rate Contributions

We introduce a numerical framework for calculating decay rate contributions when excited two-level quantum emitters are located near layered plasmonic nanostructures, particularly emphasizing the case of plasmonic nanostructures atop metal substrates where three decay channels exist: free space radiation, Ohmic losses, and excitation of surface plasmon polaritons (SPPs). The calculation of decay rate contributions is based on Huygen's equivalence principle together with a near-field to far-field transformation of the local electric field, thereby allowing us to discern the part of the electromagnetic field associated with free propagating waves rather than SPPs. The methodology is applied to the case of an emitter inside and near a gap-plasmon resonator, emphasizing strong position and orientation dependencies of the total decay rate, contributions of different decay channels, radiation patterns, and directivity of SPP excitation

Exclusive decay of Υ\Upsilon into J/ψ+χc0,1,2J/\psi+\chi_{c0,1,2}

We study the $\Upsilon$ exclusive decay into double charmonium, specifically, the $S$-wave charmonium $J/\psi$ plus the $P$-wave charmonium $\chi_{c0,1,2}$ in the NRQCD factorization framework. Three distinct decay mechanisms, i.e., the strong, electromagnetic and radiative decay channels are included and their interference effects are investigated. The decay processes $\Upsilon(1S,2S,3S)\to J/\psi+\chi_{c1,0}$ are predicted to have the branching fractions of order $10^{-6}$, which should be observed in the prospective Super $B$ factory.Comment: 22 pages, 9 figures, 3 table

Rare radiative exclusive B decays in soft-collinear effective theory

We consider rare radiative B decays such as B -> K^* gamma or B -> rho gamma in soft-collinear effective theory, and show that the decay amplitudes are factorized to all orders in alpha_s and at leading order in Lambda/m_b.By employing two-step matching, we classify the operators for radiative B decays in powers of a small parameter lambda(~ \sqrt{Lambda/m_b}) and obtain the relevant operators to order lambda in SCET_I. These operators are constructed with or without spectator quarks including the four-quark operators contributing to annihilation and W-exchange channels. And we employ SCET_II where the small parameter becomes of order Lambda/m_b, and evolve the operators in order to compute the decay amplitudes for rare radiative decays in soft-collinear effective theory. We show explictly that the contributions from the annihilation channels and the W-exchange channels vanish at leading order in SCET. We present the factorized result for the decay amplitudes in rare radiative B decays at leading order in SCET, and at next-to-leading order in alpha_s.Comment: v2: 31 pages, 11 figures. An appendix is added about the quark mass effects on radiative B decay