Physics analysis

Up until now, elementary particles and their interactions have been satisfactorily characterised by the Standard Model (SM) of particle physics. But a lot of difficult questions remain unanswered. At high energy frontiers like the LHC at CERN, some of these are being researched. The high precision/high intensity frontier made possible by exclusive observations of hadronic reactions at intermediate energies offers an alternative strategy. The upcoming antiProton ANnihilation at DArmstadt (PANDA) experiment at FAIR will utilise antiproton-nucleus and antiproton-proton interactions as diagnostic tools. The PANDA experiment may be used to analyse the spectra of many different particles. Z(4430) is among the most significant of the many XYZ states and they are being examined in numerous global experiments, such as BESIII, Belle, BaBaR, and LHCb. Therefore, integrating this research into the PANDA framework and utilising PANDA software to work with this subject is a crucial challenge for the PANDA experiment pertaining to charmonium and exotics. Z(4430) can potentially provide more precise information on mass, width, and other parameters in the PANDA detector spectrum when the entire simulation offered by the PANDA software chain is utilised. To test this, the thesis study titled "Feasibility Study of Z(4430) Exotic State at PANDA Experiment" was designed with the aim of determine whether Z(4430) is feasible in the PANDA detector spectrum. Consequently, according to the results of this study, Z(4430) is shown to be observable in the framework of the PANDA experiment.

Hyperons serve as powerful probes for investigating various aspects of quantum chromodynamics (QCD). As part of the FAIR Phase-0 program, the HADES (High-Acceptance Di-Electron Spectrometer) at GSI collected high-statistics proton-proton data using a proton beam with a kinetic energy of 4.5 GeV. The beam energy enables the production of hyperons close to threshold, facilitating studies of hyperon-hyperon interactions and searches for intermediate resonances. Currently, the ΛΛ reaction is being analyzed to extract crucial information on hyperon interactions, which is expected to be essential to understand the interiors of neutron stars. Furthermore, the first-time measurements of the Dalitz decay of the Σ0 will provide insights into transition form factors and thereby the electromagnetic structure of the Σ0. The study of Ξ- production in proton-proton collisions is valuable to address the observed excess yields observed in Ar+KCl and p+Nb reactions at HADES. This talk will highlight the ongoing hyperon physics analyses at HADES within the FAIR Phase-0 program and present selected results.

PANDA Annual Report 2023

The abundant production of hyperons in antiproton-proton annihilations open new avenues in the investigations of strong interactions and fundamental symmetries. In recent years, the BESIII experiment has demonstrated the merits of studying spin polarised and correlated hyperon-antihyperon pairs with several pioneering measurements of hyperon structure and precise tests of CP conservation.
With a beam of stored antiprotons, the PANDA experiment can take hyperon physics to a new level, benefitting from the expected huge samples of hyperon-antihyperon pairs. In this talk, I will discuss the potential of hyperon physics with PANDA in particular but also with antiproton beams in general.

The hadron spectroscopy and structure are currently very active fields of research to study the non-perturbative regime of quantum chronodynamics. The first one studies the complex structure of excited hadrons by looking at their decay products, while the latter uses lepton scattering on nucleons. Both methods require reconstruction algorithms with great efficiency and good particle identification and background rejection rates. This work aims to provide these by either improving the existing methods or developing new ones.

The first part of this document presents a feasibility study of a predicted hybrid charmonium state for the $\mathrm{\overline{P}}$ANDA experiment. Lattice QCD calculations predict the ground state hybrid charmonium to be a spin exotic with quantum numbers of $J^{PC}=1^{-+}$ at a mass of around 4.3 GeV with a width to be around 20 MeV. A machine learning based data analysis scheme is proposed to further improve the signal efficiency and the background reduction, alongside with improvements of the analysis software (PandaRoot), that are vital for this study. These improvements include a reworked clustering algorithm for the electromagnetic calorimeter (EMC) and an optimized monte carlo matching for neutral particles.

The second part of this document is about studying the proton structure. A multidimensional study of the structure function ratio $\mathrm{F_{LU}^{sin(\phi)}/F_{UU}}$ has been performed for K$^\mathrm{\pm}$, based on the measurement of beam-spin asymmetries. It uses the high statistics data recorded with the CLAS12 spectrometer at Jefferson Laboratory. $\mathrm{F_{LU}^{sin(\phi)}}$ is a twist-3 quantity that provides information about the quark gluon correlations in the proton. This document will present for the first time a simultaneous analysis of two kaon channels over a large kinematic range of $z$, $x_B$, $P_T$ and $Q^2$ with virtualities $Q^2$ ranging from 1 GeV$^2$ up to 8 GeV$^2$ using machine learning techniques for improved particle identification.

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