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Pawel Moskal

Publications and source records attributed to Pawel Moskal.

At least 37 records · Page 2Linked to original sources
arXiv2019

Etaprime and Eta Mesons with Connection to Anomalous Glue

We review the present understanding of etaprime and eta meson physics and these mesons as a probe of gluon dynamics in low-energy QCD. Recent highlights include the production mechanism of eta and etaprime mesons in proton-nucleon collisions from threshold to high-energy, the etaprime effective mass shift in the nuclear medium, searches for possible eta and etaprime bound states in nuclei as well as precision measurements of eta decays as a probe of light-quark masses. We discuss recent experimental data, theoretical interpretation of the different measurements and the open questions and challenges for future investigation.

hep-ph↗
arXiv2018

Updating spin-dependent Regge intercepts

We use new high statistics data from CLAS and COMPASS on the nucleon's spin structure function at low Bjorken x and low virtuality, Q^2 < 0.5 GeV^2, together with earlier measurements from the SLAC E-143, HERMES and GDH experiments to estimate the effective intercept(s) for spin dependent Regge theory. We find alpha_{a_1} = 0.31 \pm 0.04 for the intercept describing the high-energy behaviour of spin dependent photoabsorption together with a new estimate for the high-energy part of the Gerasimov-Drell-Hearn sum-rule, -15 \pm 2 mu b from photon-proton centre-of-mass energy greater than 2.5 GeV. Our value of alpha_[a_1} suggests QCD physics beyond a simple straight-line a_1 trajectory.

hep-ph↗
arXiv2016

Determination of the $\boldsymbol{η^3{\rm He}}$ threshold structure from the low energy $\boldsymbol{pd \to η^3{\rm He}}$ reaction

We analyze the data on cross sections and asymmetries for the $pd (dp) \to η^3{\rm He}$ reaction close to threshold and look for bound states of the $η^3 {\rm He}$ system. Rather than parameterizing the scattering matrix, as is usually done, we develop a framework in which the $η^3 {\rm He}$ optical potential is the key ingredient, and its strength, together with some production parameters, are fitted to the available experimental data. The relationship of the scattering matrix to the optical potential is established using the Bethe-Salpeter equation and the $η^3 {\rm He}$ loop function incorporates the range of the interaction given by the empirical $^3 {\rm He}$ density. We find a local Breit Wigner form of the $η^3$He amplitude $T$ below threshold with a clear peak in $|T|^2$, which corresponds to an $η^3 {\rm He}$ binding of about 0.3 MeV and a width of about 3 MeV. By fitting the potential we can also evaluate the $η^3 {\rm He}$ scattering length, including its sign, thus resolving the ambiguity in the former analyses.

nucl-th↗
arXiv2016

Status and Perspectives of the Search for Eta-Mesic Nuclei

In this report the search for eta-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the eta-nucleus bound states for light nuclei like 4He and 3He.

nucl-ex↗
arXiv2016

Etaprime interactions with nucleons and nuclei

We summarise recent progress in theory and experiment towards understanding etaprime meson interactions with nucleons and nuclei. Highlights include the production mechanism of etaprime mesons in proton-proton collisions close to threshold, the etaprime effective mass shift in nuclei and the determination of the etaprime-nucleon scattering length in free space.

hep-ph↗
arXiv2015

Search for eta-mesic nuclei with WASA-at-COSY

We search for an evidence of eta-mesic He with the WASA detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd->3Heppi- and dd->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus.In this contribution, the experimental method is shortly described and the current status of the analysis is presented.

nucl-ex↗
arXiv2014

Search for the manifestation of the mesic-nuclei on the dd-->3HeNpi excitation function measured with WASA-at-COSY

We search for an evidence of eta-mesic 4He with the WASA-at-COSY detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd-->3Heppi- and dd-->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus. In this contribution, the experimental method is shortly described and preliminary excitation functions from the 2010 data are presented.

nucl-ex↗
arXiv2014

Reaction pp -> pp πππas a background for hadronic decays of the eta-prime meson

Isospin violating hadronic decays of the ηand η' mesons into 3πmesons are driven by a term in the QCD Lagrangian proportional to the mass difference of the d and u quarks. The source giving large yield of the mesons for such decay studies are pp interactions close to the respective kinematical thresholds. The most important physics background for η,η'\toπππis coming from direct three pion production reactions. In case of the ηmeson the background for the decays is relatively low (approx 10%). The purpose of this article is to provide an estimate of the direct pion production background for the η'\to 3πdecays. Using the inclusive data from COSY-11 experiment we have extracted differential cross section for the pp\to pp-multipion production reactions with the invariant mass of the pions equal to the η' meson mass and estimated an upper limit for the signal to background ratio for studies of the η'\toπ^+π^-π^0 decay.

hep-ex↗
arXiv2013

Studies of systematic uncertainties of polarization estimation for experiments with WASA detector at COSY

In November 2010, the azimuthally symmetric WASA detector and the polarized proton beam of COSY, have been used to collect a high statistics sample of $\vec{p}p \rightarrow ppη$ reactions in order to determine the analyzing power as a function of the invariant mass spectra of the two particle subsystems. Here, we show studies of the influence of the beam and target characteristics such as location and direction on the determination of the polarization.

nucl-ex↗
arXiv2013

Search for eta-mesic helium via deuteron-deuteron reactions with the WASA-at-COSY facility

The eta-mesic nuclei in which the eta meson is bound with nucleus via strong interaction was postulated already in 1986, however till now no experiment confirmed empirically its existence. The discovery of this new kind of an exotic nuclear matter would be very important for better understanding of the eta meson structure and its interaction with nucleons. The search for eta-mesic helium is carried out with high statistic and high acceptance with the WASA-at-COSY detection setup in the Forschungszentrum Julich. The search is conducted via the measurement of the excitation function for the chosen decay channels of the 4He-eta system. Untill now two reactions dd->(4He-eta)bs->3He p pi- and dd->(4He-eta)bs->3He n pi0 have been measured with the beam momentum ramped around the eta production threshold. This report includes the description of experimental method and status of the analysis.

nucl-ex↗
arXiv2012

Search for eta-mesic Helium with the WASA-at-COSY detector

A search for the 4He-eta bound state via exclusive measurement of the excitation function for the dd->3Heppi- reaction, was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta production in the dd -> 4He-eta reaction at 2.336 GeV/c. The corresponding excess energy in the 4He-eta system varied from -51.4 MeV to 22 MeV. The shape of the excitation function for the dd -> 3Heppi- was examined. No signal of the 4He-eta bound state was observed in the excitation function.

nucl-ex↗
arXiv2011

Search for He-eta bound states with the WASA-at-COSY facility

The existence of eta-mesic nuclei in which the eta meson is bound in a nucleus by means of the strong interaction was postulated already in 1986, albeit not yet confirmed it by experiment. The discovery of this new kind of an exotic nuclear matter would be very important as it might allow for a better understanding of the eta meson structure and its interaction with nucleons. The search for eta-mesic helium 4He-eta is carried out with high statistics and high acceptance with the WASA detector, installed at the cooler synchrotron COSY of the Research Center Juelich. The search is conducted via the measurement of the excitation function for selected decay channels of the 4He-eta system. In the experiment, performed in November 2010, two reactions dd->(4He-eta)bs ->3He p pi- and dd->(4He-eta)bs ->3He p pi0 were measured with a beam momentum ramped from 2.127GeV/c to 2.422GeV/c. The report includes the description of the experimental method and status of the measurement.

nucl-ex↗
arXiv2011

Revealing Bell's Nonlocality for Unstable Systems in High Energy Physics

Entanglement and its consequences - in particular the violation of Bell inequalities, which defies our concepts of realism and locality - have been proven to play key roles in Nature by many experiments for various quantum systems. Entanglement can also be found in systems not consisting of ordinary matter and light, i.e. in massive meson--antimeson systems. Bell inequalities have been discussed for these systems, but up to date no direct experimental test to conclusively exclude local realism was found. This mainly stems from the fact that one only has access to a restricted class of observables and that these systems are also decaying. In this Letter we put forward a Bell inequality for unstable systems which can be tested at accelerator facilities with current technology. Herewith, the long awaited proof that such systems at different energy scales can reveal the sophisticated "dynamical" nonlocal feature of Nature in a direct experiment gets feasible. Moreover, the role of entanglement and CP violation, an asymmetry between matter and antimatter, is explored, a special feature offered only by these meson-antimeson systems.

quant-ph↗
arXiv2011

Study of the eta meson production with the polarised proton beam

The azimuthally symmetric WASA detector and the polarised proton beam of COSY, enable investigations of energy and angular dependence of the beam analysing power in the pp --> ppeta reaction. The aim of the studies is the determination of the partial wave contributions via interference terms which are inaccessible from spin averaged observables. The partial wave decomposition is mandatory for the understanding of the reaction dynamics and for the determination of the eta-proton interaction, independently of the theoretical paradigm used.

nucl-ex↗
arXiv2010

Study of the Decoherence of Entangled Kaons by the Interaction with Thermal Photons

The KLOE-2 detector is a powerful tool to study the temporal evolution of quantum entangled pairs of kaons. The accuracy of such studies may in principle be limited by the interaction of neutral kaons with thermal photons present inside the detector. Therefore, it is crucial to estimate the probability of this effect and its influence on the interference patterns. In this paper we introduce the phenomenology of the interaction of photons with neutral kaons and present and discuss the obtained quantitative results.

nucl-th↗
arXiv2009

Isospin dependence of the eta meson production in hadronic collisions

Based on recent COSY-11 results of measurements of total cross sections for the quasi-free pn-->pn eta reaction we determine the isospin I=0 component of the total cross section for the NN-->NN eta reaction down to the threshold. We show that the energy dependence of the total cross section ratios {σ_{I=0}(pn-->pn eta)}/{σ(pp-->pp eta)} and σ_{I=0}(pn-->pn eta)}/{σ(pn-->d eta)} can be described using the Faldt and Wilkin analitical parametrization of the nucleon-nucleon final state interaction.

nucl-ex↗
arXiv2009

Study of the Low Energy Dynamics in the ppK+K- System with the Cosy-11 Magnetic Spectrometer

The near threshold production of K+K- pairs in proton-proton collisions has been investigated at the cooler synchrotron COSY below and above the threshold for the ϕmeson production. The experimental excitation function determined for the pp-->ppK+K- reaction differs from theoretical expectations including proton-proton final state interaction. The discrepancy may be assigned to the influence of K+K- or pK interaction. In this article we present distributions of the cross section for the pp-->ppK+K- reaction as a function of the invariant masses of two and three particle subsystems at excess energies of Q=10 MeV and 28 MeV.

hep-ph↗