Measurement of the invariant mass distributions for the reaction at excess energy of

Klaja, P.; Moskal, P.; Czerwiński, E.; Czyzykiewicz, R.; Deloff, A.; Gil, Damian Tomasz; Grzonka, D.; Jarczyk, L.; Kamys, B.; Khoukaz, A.; Klaja, J.; Nakayama, K.; Oelert, W.; Ritman, J.; Sefzick, T.; Siemaszko, M.; Silarski, M.; Smyrski, J.; Täschner, A.; Wolke, M.; Zdebik, J.; Zieliński, Marcin; Zipper, W.

doi:10.1016/j.physletb.2009.12.056

Cited by 20 publications

(48 citation statements)

References 36 publications

(39 reference statements)

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“…Since the enhancement is similar in η and η case [14], and the strength of proton-η and proton-η interaction seems to be different [12], one can conclude that the observed enhancement is not caused by a proton-meson interaction, especially that calculations assuming a significant contribution of Pwave in the final state [70], and models including energy dependence of the production amplitude [71,72], reproduce the data within error bars. Therefore, the determination of the spin observables and extraction of the contribution from the higher partial waves is mandatory for the understanding of the observed enhancements in the discussed invariant mass spectra.…”

Section: Threshold Production Of the η-Nucelon-nucleon And η -Nucleonmentioning

confidence: 64%

“…One of the interesting, and still not fully understood observations from the threshold production of η and η mesons, are large enhancements in invariant masses of two-particle subsystems seen both in the ppη [13,36,37] and ppη [14] systems. Since the enhancement is similar in η and η case [14], and the strength of proton-η and proton-η interaction seems to be different [12], one can conclude that the observed enhancement is not caused by a proton-meson interaction, especially that calculations assuming a significant contribution of Pwave in the final state [70], and models including energy dependence of the production amplitude [71,72], reproduce the data within error bars.…”

Section: Threshold Production Of the η-Nucelon-nucleon And η -Nucleonmentioning

confidence: 99%

“…E.g. enhancements in the meson-nucleon invariant mass distribution due to the meson-nucleon interaction may be mixed with effects due to the p-wave nucleon-nucleon production [13,14]. Experimental determination of contributions from various partial waves is difficult and requires measurements with polarised beams and targets.…”

Section: Introductionmentioning

confidence: 99%

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Few-Body Aspects of the Near Threshold Pseudoscalar Meson Production

Moskal

2014

Few-Body Syst

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During the last decade large samples of data have been collected on the production of the groundstate pseudoscalar mesons in collisions of proton or deuteron beam with hydrogen or deuterium target. These measurements have been performed in the vicinity of the kinematical threshold for meson production where only a few partial waves in both initial and final state are expected to contribute to the production process. This simplifies significantly the interpretation of the data, yet still appears to be challenging due to the three or four particle final state systems with a complex hadronic potential. We review experiments and phenomenology of the near threshold production of the ground-state mesons in the few-body final states as for example: nucleus-meson and nucleon-nucleon-meson, and report on the status of the search of the mesic-nuclei (a meson-nucleus bound states). Experimental advantages of measurements close to the kinematical threshold are discussed, and general features of the production mechanism of the η and η mesons in the nucleon-nucleon collisions are presented emphasising results of measurements of spin and isospin dependence of the production cross sections.

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Section: Threshold Production Of the η-Nucelon-nucleon And η -Nucleonmentioning

confidence: 64%

Section: Threshold Production Of the η-Nucelon-nucleon And η -Nucleonmentioning

confidence: 99%

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Few-Body Aspects of the Near Threshold Pseudoscalar Meson Production

Moskal

2014

Few-Body Syst

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“…The COSY-11 acceptance for Figure 3. Experimental total cross sections for the ω production [8][9][10][11][12][13] and η production [11,[14][15][16][17][18][19], together with the present data points. Solid lines present theoretical predictions for the ω and η production cross sections from Ref.…”

Section: Data Analysis and Resultsmentioning

confidence: 99%

Near-threshold charged kaon pair production in two protons collisions

Gil

Smyrski

2016

EPJ Web Conf.

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Abstract. The pp → ppK + K − reaction was measured near threshold at excess energy Q = 4.5 MeV using the COSY-11 detection system installed at the COSY-Juelich accelerator. Preliminary value of upper limit of the total cross section was determined. This limit indicates that an enhancement of the total cross section close to the threshold, caused by the final state interaction, is smaller than suggested by extrapolation of data measured at higher energies. Physics motivationThe energy dependence of the pp → ppK + K − total cross section close to threshold is very sensitive to the interactions between particles in the final state, and therefore is well suited for studies of these interactions. There are many interesting topics connected with the interactions of the final state kaons and protons. For example, the K + K − interaction is crucial for understanding the structure of the scalar mesons f 0 (980) and a 0 (980), which according Ref. [1,2] are KK molecules. In turn, the K − p interaction is interesting from the point of view of study the nature of the Λ(1405) hyperon, which is considered as a K − p molecular state [3]. There are also some astrophysical aspects of studying kaons production reactions, like description of neutron stars structure [4]. Elementary reactions of kaon pair production in pp collisions are also important for better understanding of the properties of kaons inside dense baryonic matter [5]. The existing data for the kaon pair production in pp collisions were measured for excess energies higher than Q = 6 MeV, with exception of one point at 3 MeV, for which only upper limit of the total cross section was determined. On the other hand, data very close to threshold (for Q < 6 MeV) are crucial for distinguishing between various models of the final state interaction (FSI) in the ppK + K − system. Therefore, we performed a high luminosity measurement at Q = 4.5 MeV. ExperimentThe measurement was performed with the COSY-11 detection system, described in details in Ref. [6], at the COSY-Juelich accelerator. A principle of the measurement is presented in Fig. 1. Internal proton beam of the COSY was scattered on the COSY-11 H 2 cluster target. The beam momentum

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“…For the studies at light ion storage rings as COSY the pp → ppη reaction close to threshold seems to be most promising. The cross-section for the pp → ppη reaction was measured by the COSY-11 [22][23][24][25], SPE-SIII [26] and DISTO [27] Collaborations. In fig.…”

Section: Experiments Using Pp → Ppη η Reactionmentioning

confidence: 99%

Reaction pp $ \rightarrow$ pp $ \pi$ $ \pi$ $ \pi$ as a background for hadronic decays of the $ \eta^{{\prime}}_{}$ meson

2011

Self Cite

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Abstract. Isospin violating hadronic decays of the η and η mesons into 3π mesons 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 → πππ is coming from direct three-pion production reactions. In case of the η meson the background for the decays is relatively low (≈ 10%). The purpose of this article is to provide an estimate of the direct pion production background for the η → 3π decays. Using the inclusive data from the COSY-11 experiment we have extracted the differential cross-section for the pp → 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 → π + π − π 0 decay. Motivation Three-pion decays of the η and η mesonsThe η and η decays into three pions violate isospin and occur only due to u and d quark mass difference. The decay width is sensitive to the mass difference:, where the Γ 0 term can be calculated in the isospin limit m d = m u . The decays might provide a precise constraint for the light-quark mass ratios [1].In the case of the η meson the existence of the isospin conserving decays into three pseudoscalars (ππη) implies that instead of the decay width for the isospin violating πππ channel one can measure the ratioas it was proposed by Gross, Treiman and Wilczek [2]. Such measurement is self-contained since it does not require normalization for the partial decay width from other experiments. Additionally, simultaneous measurement of the two decays modes, with similar final states, ensures that many systematic uncertainties will cancel. a

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Measurement of the invariant mass distributions for the reaction at excess energy of

Cited by 20 publications

References 36 publications

Few-Body Aspects of the Near Threshold Pseudoscalar Meson Production

Few-Body Aspects of the Near Threshold Pseudoscalar Meson Production

Near-threshold charged kaon pair production in two protons collisions

Reaction pp $ \rightarrow$ pp $ \pi$ $ \pi$ $ \pi$ as a background for hadronic decays of the $ \eta^{{\prime}}_{}$ meson

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