Strong and electromagnetic decays of the radially excited $$D_s$$ and $$B_s$$ mesons in light cone QCD sum rules

Recently, LHCb Collaboration announced the discovery of radial excitations of $$D_s$$ D s and $$B_s$$ B s mesons. In present work, we calculate the most promising strong and electromagnetic decay widths of radially excited $$D_s(2S)$$ D s ( 2 S ) and $$B_s(2S)$$ B s ( 2 S ) mesons within the light cone QCD sum rules method.

Remarks on the electromagnetic decays of the neutral pion

We propose a simple classical electrodynamics model in which a Lorentz pseudoscalar field and a Dirac field are present in the general Lagrangian of the system. The model is constructed by allowing explicit violation of chiral symmetry. This approach is intended to predict possible electromagnetic decays of the neutral pion in effective terms.

Production and electromagnetic decay of hyperons: a feasibility study with HADES as a phase-0 experiment at FAIR

A feasibility study has been performed in order to investigate the performance of the HADES detector to measure the electromagnetic decays of the hyperon resonances $$\Sigma (1385)^{0}$$ Σ ( 1385 ) 0 , $$\Lambda (1405)$$ Λ ( 1405 ) and $$\Lambda (1520)$$ Λ ( 1520 ) as well as the production of double strange baryon systems $$\Xi ^{-}$$ Ξ - and $$\Lambda $$ Λ $$\Lambda $$ Λ in p + p reactions at a beam kinetic energy of $$4.5\,{\mathrm{GeV}}$$ 4.5 GeV . The existing HADES detector will be upgraded by a new Forward Detector, which extends the detector acceptance into a range of polar angles that plays a crucial role for these investigations. The analysis of each channel is preceded by a consideration of the production cross-sections. Afterwards the expected signal count rates using a target consisting of either liquid hydrogen or polyethylene are summarized.

Next-to-next-to-leading-order radiative corrections to e+e− → χcJ + γ at B factory

Within the nonrelativistic QCD (NRQCD) factorization framework, we have computed the $$ \mathcal{O}\left({\alpha}_s^2\right) $$ O α s 2 corrections to the exclusive production of P-wave spin-triplet charmonia χcJ (J = 0, 1, 2) accompanied with a hard photon at B factory. For the first time, we have explicitly verified the validity of NRQCD factorization for exclusive P-wave quarkonium production to two-loop order. Unlike the χcJ electromagnetic decays, the $$ \mathcal{O}\left({\alpha}_s^2\right) $$ O α s 2 corrections are found to be smaller than the $$ \mathcal{O} $$ O (αs) corrections in all three channels e+e− → χc0,1,2 + γ. In particular, the $$ \mathcal{O}\left({\alpha}_s^2\right) $$ O α s 2 corrections appear moderate for χc1 + γ case, and marginal for χc0 + γ. Moreover, the predictions in next-to-next-to-leading order (NNLO) accuracy for the production rates of χc0,1 + γ are insensitive to the renormalization and factorization scales. All these features may indicate that perturbative expansion in these two channels exhibits a decent convergence behavior. By contrast, both the $$ \mathcal{O} $$ O (αs) and $$ \mathcal{O}\left({\alpha}_s^2\right) $$ O α s 2 corrections to the χc2 + γ production rate are sizable, which reduce the Born order cross section by one order of magnitude after including the NNLO perturbative corrections. Taking the values of the long-distance NRQCD matrix elements from nonrelativistic potential model, our prediction to χc1 + γ production rate is consistent with the recent Belle measurement. The NNLO predictions to the χc0,2 + γ production rates are much smaller than that for χc1 + γ, which seems to naturally explain why the e+e− → χc0,2 + γ channels have escaped experimental detection to date.

Study of exotic mesons in pp and AA collisions

The possibility of study of exotic mesons is discussed. The paper includes detailed analysis of strong, weak and electromagnetic decays containing charmed quark-antiquark pair, physics simulation and event reconstruction at NICA.