Study of doubly strange systems using stored antiprotons

Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the P‾ANDA experiment at FAIR. For the first time, high resolution γ-spectroscopy of doubly strange ΛΛ-hypernuclei will be performed, thus complementing measurements of ground state decays of ΛΛ-hypernuclei at J-PARC or possible decays of particle unstable hypernuclei in heavy ion reactions. High resolution spectroscopy of multistrange Ξ−-atoms will be feasible and even the production of Ω−-atoms will be within reach. The latter might open the door to the |S|=3 world in strangeness nuclear physics, by the study of the hadronic Ω−-nucleus interaction. For the first time it will be possible to study the behavior of Ξ‾+ in nuclear systems under well controlled conditions

The potential of Λ\Lambda and Ξ−\Xi^- studies with PANDA at FAIR

International audienceThe antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: ${\bar{p}}p \rightarrow {\bar{\varLambda }}\varLambda$ and ${\bar{p}}p \rightarrow {\bar{\varXi }}^+\varXi ^-$. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA

Feasibility studies for the measurement of time-like proton electromagnetic form factors from pˉp→μ+μ−\bar{p}p \rightarrow \mu ^+\mu ^- at P‾ANDA\overline{\text {P}}\text {ANDA} at FAIR

International audienceThis paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, $|G_{E}|$ and $|G_{M}|$, using the $\bar{p} p \rightarrow \mu ^{+} \mu ^{-}$ reaction at $\overline{\text {P}}\text {ANDA}$ (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at $\overline{\text {P}}\text {ANDA}$, using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is $\bar{p} p \rightarrow \pi ^{+} \pi ^{-}$, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

Technical Design Report for the Panda Forward Spectrometer Calorimeter

This document is devoted to the electromagnetic calorimeter of the Forward Spectrometer and describes the design considerations, the technical layout, the expected performance, and the production readiness

Technical Design Report for the Panda Forward Spectrometer Calorimeter

This document is devoted to the electromagnetic calorimeter of the Forward Spectrometer and describes the design considerations, the technical layout, the expected performance, and the production readiness

Eperimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR

We address the possibility of accessing nucleon-to-pion (πN) Transition Distribution Amplitudes (TDAs) from p¯p→e+e−π0 reaction with the future \={P}ANDA detector at the FAIR facility. At high center of mass energy and high invariant mass of the lepton pair q2, the amplitude of the signal channel p¯p→e+e−π0 admits a QCD factorized description in terms of πN TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring p¯p→e+e−π0 with the \={P}ANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, {\it i.e.} p¯p→π+π−π0 were performed for the center of mass energy squared s=5 GeV2 and s=10 GeV2, in the kinematic regions 3.00.5 in the proton-antiproton center of mass frame. Results of the simulation show that the particle identification capabilities of the \={P}ANDA detector will allow to achieve a background rejection factor at the level of 108 (2⋅107) at low (high) q2 while keeping the signal reconstruction efficiency at around 40% and that a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 fb−1 of integrated luminosity. The future measurement of the signal channel cross section with \={P}ANDA will provide a new test of perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing πN TDAs