Partial wave analysis

Abstract

Abstract. The project A.2 of the SFB/TR16 "Subnuclear Structure of Matter" aimed at a combined multichannel partial wave analysis of all or of most data on pion and photo-induced reactions for invariant masses from the Δ(1232) region to 2300 MeV. In this review the most important results are presented. It is shown that the data and their partial wave analysis have improved our understanding of the dynamics of excited light-quark baryons significantly.

Few-body quark dynamics for doubly heavy baryons and tetraquarks

“…Another extreme is to view diquarks as a type of "Voodoo few-body 3 ". In this empirical approach to fewbody physics, to estimate the energy and wave function of, say, (a 1 a 2 a 3 ), with masses m i and interaction v i j (r), one first solves for (a 1 a 2 ) with v 12 alone, with energy η 12 , then estimates the bound state of a point-like (a 1 a 2 ) of mass m 1 + m 2 , or perhaps m 1 + m 2 + ε 2 in some variants, located at R 12 , interacting with a 3 through the potential v 13 12 ), resulting in binding energy η 12,3 , and the whole energy is given by η 12 + η 12,3 . For a 4-body system, the (a 1 a 2 ) and (a 3 a 4 ) systems are estimated first, and then a third two-body equation is solved for (a 1 a 2 ) interacting with (a 3 a 4 ) via a potential v i j (R 12 − R 34 ), where Σ denotes i = 1, 2 and j = 3, 4 throughout this paper, in particular in Sec.…”

Observation of a structure in the M$_{pη}$ invariant mass distribution near 1700 MeV/$c^2$ in the $\mathbf{γp \rightarrow p π^0 η} $ reaction

“…3. Acceptance and efficiency for events of the γp → pπ 0 η reaction as a function of the invariant mass Mpη obtained in GEANT3 [35] simulations, assuming a distribution of final state particle 4-momenta according to a phase space distribution (stars) and to the predictions of a partial wave analysis (PWA) [36](circles). The full symbols represent the probability to reconstruct γp → pπ 0 η events under the condition M pπ 0 ≤1190 MeV, while the open symbols refer to the acceptance and efficiency without this cut.…”

“…The acceptance and efficiency have been determined with the CBELSA/TAPS analysis package using GEANT3 Monte Carlo simulations [35] with a full implementation of the detector system, including e.g., detector thresholds and trigger conditions. The γp → pπ 0 η reaction has been simulated, assuming a phase space distribution of the final state particles and alternatively a distribution provided by a partial wave analysis (PWA) [36] based on the experimental results of [17,19]. The detector acceptance and efficiency is given by the ratio of the number of reconstructed to generated events for each M pη invariant mass bin.…”

Few-Body Insights of Multiquark Exotic Hadrons

“…However, the missing resonances are not very much coupled to the typical investigation channels πN or γN , which privilege states with one pair of quarks shared with the target nucleon N . In recent photoproduction experiments with improved statistics, some of the missing states have been identified, which cannot be accommodated as made of a ground-state diquark and a third quark [4].…”