M. Nowakowski

Time delay plots of unflavoured baryons

Abstract We explore the usefulness of the existing relations between the S -matrix and time delay in characterizing baryon resonances in pion–nucleon scattering. We draw attention to the fact that the existence of a positive maximum in time delay is a necessary criterion for the existence of a resonance and should be used as a constraint in conventional analyses which locate resonances from poles of the S -matrix and Argand diagrams. The usefulness of the time delay plots of resonances is demonstrated through a detailed analysis of the time delay in several partial waves of πN elastic scattering.

Time delayed K+N reactions and exotic baryon resonances

Evidence and hints, from both the theoretical and experimental sides, of exotic baryon resonances with B = S, have been with us for the last 30 years. The poor status of the general acceptance of these Z* resonances is partly due to the prejudice against penta-quark baryons and partly due to the opinion that a proof of the existence of exotic states must be rigorous. This can refer to the quality and amount of data gathered, and also to the analytical methods applied in the study of these resonances. It then seems mandatory that all possibilities and aspects be exploited. We do that by analysing the time delay in K+N scattering, encountering clear signals of the exotic Z* resonances close to the pole values found in partial wave analyses.

Collision times in ππ and πK scattering and spectroscopy of meson resonances

Abstract Using the concept of collision time (time delay) introduced by Eisenbud and Wigner and its connection to on-shell intermediate unstable states, we study mesonic resonances in ππ and πK scattering. The time-delay method proves its usefulness by revealing the spectrum of the well known ρ - and K ∗ -mesons and by supporting some speculations on ρ -mesons in the 1200 MeV region. We use this method further to shed some light on more speculative meson resonances, among others the enigmatic scalars. We confirm the existence of chiralons below 1 GeV in the unflavoured and strange meson sector.

Hidden evidence of nonexponential nuclear decay

The framework to describe natural phenomena at their basics being quantum mechanics, there exist a large number of common global phenomena occurring in different branches of natural sciences. One such global phenomenon is spontaneous quantum decay. However, its long time behavior is experimentally poorly known. Here we show, that by combining two genuine quantum mechanical results, it is possible to infer on this large time behavior, directly from data. Specifically, we find evidence for nonexponential behavior of alpha decay of

Determining the size of the proton

^{8}\mathrm{Be}

Breit Equation with Form Factors in the Hydrogen Atom

at large times from experiments.

THE MINIMUM AND MAXIMUM TEMPERATURE OF BLACK BODY RADIATION

Abstract A measurement of the Lamb shift of 49,881.88(76) GHz in muonic hydrogen in conjunction with theoretical estimates of the proton structure effects was recently used to deduce an accurate but rather small radius of the proton. Such an important shift in the understanding of fundamental values needs reconfirmation. Using a different approach with electromagnetic form factors of the proton, we obtain a new expression for the transition energy, Δ = E 2 P 3 / 2 f = 2 − E 2 S 1 / 2 f = 1 , in muonic hydrogen and deduce a proton radius, r p = 0.831 fm .

Evidence of pentaquark states from K+ N scattering data?

The Breit equation with two electromagnetic form factors is studied to obtain a potential with finite-size corrections. This potential with proton structure effects includes, apart from the standard Coulomb term, the Darwin term, retarded potentials, spin–spin and spin–orbit interactions corresponding to the fine and hyperfine structures in the hydrogen atom. Analytical expressions for the hyperfine potential with form factors and the subsequent energy levels including the proton structure corrections are given using the dipole form of the form factors. Numerical results are presented for the finite-size corrections in the 1S and 2S hyperfine splittings in the hydrogen atom, the Sternheim observable D21 and the 2S and 2P hyperfine splittings in muonic hydrogen. Finally, a comparison with some other existing methods in the literature is presented.

Proton form factor effects in hydrogenic atoms

We show, in different ways, that in the ubiquitous phenomenon of black body radiation there exists a minimum and maximum temperature. These limiting values are so small and large respectively, that they are of no practical use, except in an extreme situation of black hole evaporation where they lead to maximum and minimum mass.

Resonances inη-light nucleus systems

Motivated by the recent experimental evidence of the exotic B=S=+1 baryonic state Θ (1540), we examine the older existing data on K+N elastic scattering through the time delay method. We find positive peaks in time delay around 1.545 and 1.6 GeV in the D03 and P01 partial waves of K+N scattering respectively, in agreement with experiments. We also find an indication of the J=3/2 Θ* spin-orbit partner to the Θ, in the P03 partial wave at 1.6 GeV. We discuss the pros and cons of these findings in support of the interpretation of these peaks as possible exotics.