Physics analysis

One of the most interesting fields in modern high energy physics is
the experimental study of quantum chromodynamics. The PANDA-
experiment at FAIR aims to explore this field by probing hadrons with
unprecedented precision and sensitivity. It will use proton-antiproton
collisions to reach center-of-mass energies of up to 5.5 GeV. Combined
with a high luminosity, this will make the detection of exotic resonances
with tiny cross sections feasible. In order to support the experiment
with simulations, the software framework PANDARoot was developed.
In this talk, the reconstruction of a hybrid candidate in the charmo-
nium sector with PANDARoot will be presented. The decay channel
involving the hybrid candidate ultimately decays into seven photons,
which makes it an excellent candidate to evaluate the performance of
the electromagnetic calorimeter. While seven photons already create
immense combinatorical background within the signal channel, there
exist at least four background channels with a very similar decay pat-
tern. Hence it is important to maximize the statistical significance of
the signal. For this, different optimization algorithms were evaluated,
where a genetic algorithm was found to be the most suitable one. Its
features and performance will be discussed. This project is supported
by BMBF and HIC for Fair.

The PANDA experiment is one of the main pillars of the FAIR facility, currently under construction in Darmstadt, Germany. The PANDA will be a fixed target experiment designed for the study of non-perturbative phenomena of the strong interaction. Strange hyperon production is governed by the mass of the strange quark, m(s) ∼ 100 MeV, which corresponds to the confinement domain. Thus, hyperons are suitable probes in this energy region. This work is a simulation study focused on the feasibility of studying the production of the Sigmabar and Lambda hyperons in the pbar p ->Sigmabar Lambda reaction with the PANDA detector. A 10^4 events sample simulated at pbeam = 1.771 GeV/c is used to perform a single-tag (inclusive) and a double-tag (exclusive) event selection. From the former, it is concluded that the single-tag method does not provide with the clean signal required for spin observables extraction. In contrast, exclusive event selection provides with a signal reasonably clean from combinatorial background and completely clean from generic hadronic background events. A signal ( Sigmabar Lambda) reconstruction efficiency of e = 5.3 ± 0.2 % is obtained for exclusive event selection. The corresponding signal to background ratio is S/B Total ∼ 6 and the significance value
is ∼ 21.
In addition, an exclusive event selection is performed on a 10^4 events sample simulated at pbeam = 6 GeV/c. Almost all the generic hadronic background events are removed by the applied selection criteria. At this beam momentum, the obtained signal efficiency is e = 6.1 ± 0.3%, the signal to total background ratio is S/B Total ∼ 4 and the significance is ∼ 22. Both efficiencies are smaller compared to a previous simulation study on this channel, but are large enough to enable a study of the exclusive production of the pbar p -> Sigmabar Lambda reaction at PANDA. The difference between the results of this work and the previous work is attributed to the more realistic implementation of the signal production mechanism, as well as the detector and reconstruction algorithms.

Despite the successes of the Standard Model of particle physics, it remains a challenge to understand the dynamics of the strong interaction among quarks and gluons. At small distance scales or at high energies, the underlying theory, the Quantum Chromodynamics (QCD), is well tested and understood. Our understanding of the strong interaction deteriorates dramatically at larger distances scales such as the size of the nucleon. This "strong QCD regime” exhibits spectacular effects such as the generation of hadron masses and color confinement. Moreover, the nature of QCD implies the existence of gluon-rich hadrons, such as glueballs and hybrids, multi-quark states, and molecules. The annihilation of matter with antimatter in the mass regime of charmonium has proven to be an ideal environment to discover new forms of hadronic matter. Experiments using electron-positron annihilations at energies in the charmonium-mass regime conducted with the BESIII spectrometer (Beijing, China) revealed a complete new class of hidden-charm matter. A complementary research program is in development with the aim to collide an intense beam of cooled anti-protons with protons or nuclei. This experiment, called PANDA at FAIR, has the ambition to carry out comprehensive spectroscopy studies of hadrons in the strange, charm, and gluon-rich regimes. In this talk, I will highlight the recent discoveries made by BESIII and give perspectives of PANDA in this exciting field of research.

The PANDA experiment represents the central part of the hadron physics
programme at the new Facility for Antiproton and Ion Research (FAIR) under
construction at GSI/Darmstadt (Germany). The multi-purpose PANDA detector in
combination with an intense and high-quality antiproton beam allows for coverage
of a broad range of different aspects of QCD, and it is best suited for charmonium
spectroscopy. We present a comprehensive PANDA Monte Carlo simulation study for
precision resonance energy scan measurements, using the example of the charmonium-like
$X(3872)$ state discussed to be exotic. Apart from the proof of principle for
natural decay width and line-shape measurements of very narrow resonances, the
achievable sensitivities are quantified for the concrete example of the $X(3872)$.
The discussed measurement is uniquely possible with a $\bar{p}p$ annihilation
experiment such as PANDA at FAIR.

PANDA Collaboration Meeting 18/3 Minutes

This paper summarises a comprehensive Monte Carlo simulation study for precision resonance energy scan measurements. Apart from the proof of principle for natural width and line-shape measurements of very narrow resonances with PANDA, the achievable sensitivities are quantified for the concrete example of the charmonium-like $X(3872)$ state discussed to be exotic, and for a larger parameter space of various assumed signal cross-sections, input widths and luminosity combinations. PANDA is the only experiment that will be able to perform a precision resonance energy scan of such a narrow state with quantum numbers of spin and parities that differs from $J^{PC} = 1^{--}$.