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Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. url  doi
openurl 
  Title Study of the quasi-free np -> np pi(+)pi(-) reaction with a deuterium beam at 1.25 GeV/nucleon Type Journal Article
  Year 2015 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 750 Issue Pages 184-193  
  Keywords Two-pion production; np collisions; Resonance excitations  
  Abstract The tagged quasi-free np -> np pi(+)pi(-) reaction has been studied experimentally with the High Acceptance Di-Electron Spectrometer (HADES) at GSI at a deuteron incident beam energy of 1.25 GeV/nucleon (root S similar to 2.42 GeV/c for the quasi-free collision). For the first time, differential distributions of solid statistics for pi(+)pi(-) production in np collisions have been collected in the region corresponding to the large transverse momenta of the secondary particles. The invariant mass and angular distributions for the np -> np pi(+)pi(-) reaction are compared with different models. This comparison confirms the dominance of the t-channel with Delta Delta contribution. It also validates the changes previously introduced in the Valencia model to describe two-pion production data in other isospin channels, although some deviations are observed, especially for the pi(+)pi(-) invariant mass spectrum. The extracted total cross section is also in much better agreement with this model. Our new measurement puts useful constraints for the existence of the conjectured dibaryon resonance at mass M similar to 2.38 GeV and with width Gamma similar to 70 MeV. (C) 2015 The Authors. Published by Elsevier B.V.  
  Address [Finocchiaro, P.] Ist Nazl Fis Nucl, Lab Nazl Sud, I-95125 Catania, Italy, Email: akurilkin@jinr.ru;  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000364250600031 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2469  
Permanent link to this record
 

 
Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. doi  openurl
  Title Deep sub-threshold K*(892)(0) production in collisions of Ar + KCl at 1.76A GeV Type Journal Article
  Year 2013 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A  
  Volume 49 Issue 3 Pages 34 - 7pp  
  Keywords  
  Abstract Results on the deep sub-threshold production of the short-lived hadronic resonance K*(892)(0) are reported for collisions of Ar + KCl at 1.76 A GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The K*(892)(0) production probability per central collision of P-K*0 = (4.4 +/- 1.1 +/- 0.5) x 10(-4) and the K*(892)(0)/K-0 ratio of P-K*0/P-K0 = (1.9 +/- 0.5 +/- 0.3) x 10(-2) are determined at the lowest energy so far (i.e. deep below the threshold for the corresponding production in nucleon-nucleon collisions, root s(NN)-root s(thr) = -340MeV). The K*(0)/K-0 ratio is compared with results of other experiments and with the predictions of the UrQMD transport approach and of the statistical hadronization model. The experimental K*(0) yield and the K-*0/K-0 ratio are overestimated by the transport model by factors of about five and two, respectively. In a chemically equilibrated medium the ratio corresponds to a temperature of the thermalized system being systematically lower than the value determined by the yields of the stable and long-lived hadrons produced in Ar + KCl collisions. From the present measurement, we conclude that sub-threshold K* production either cannot be considered to proceed in a system being in thermal equilibrium or these short-lived resonances appear undersaturated, for example as a result of the rescattering of the decay particles in the ambient hadronic medium.  
  Address Inst Nazl Fis Nucl, Lab Nazl Sud, I-95125 Catania, Italy, Email: kotte@hzdr.de  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6001 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000317855000006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1426  
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Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. url  doi
openurl 
  Title Hyperon production in Ar plus KCl collisions at 1.76A GeV Type Journal Article
  Year 2011 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A  
  Volume 47 Issue 2 Pages 21 - 9pp  
  Keywords  
  Abstract We present transverse momentum spectra, rapidity distribution and multiplicity of Lambda-hyperons measured with the HADES spectrometer in the reaction Ar(1.76A GeV) + KCl. The yield of Xi(-) is calculated from our previously reported Xi(-)/(Lambda+Sigma(0)) ratio and compared to other strange particle multiplicities. Employing a strangeness balance equation the multiplicities of the yet unmeasured Sigma(+/-)-hyperons can be estimated. Finally a statistical hadronization model is used to fit the yields of pi(-), K+, K-s(0), K-, phi, Lambda and Xi(-). The resulting chemical freeze-out temperature of T = (76 +/- 2) MeV is compared to the measured slope parameters obtained from fits to the transverse mass distributions of the different particles.  
  Address [Agakishiev, G.; Belyaev, A.; Chernenko, S.; Fateev, O.; Lapidus, K.; Zanevsky, Y.] Joint Inst Nucl Res, Dubna 141980, Russia, Email: Lorenz@Physik.uni-frankfurt.de  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6001 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000288551700007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 540  
Permanent link to this record
 

 
Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. doi  openurl
  Title pp and pi pi intensity interferometry in collisions of Ar+KCl at 1.76A GeV Type Journal Article
  Year 2011 Publication European Physical Journal A Abbreviated Journal Eur. Phys. J. A  
  Volume 47 Issue 5 Pages 63 - 8pp  
  Keywords  
  Abstract Results on pp, pi(+) pi(+), and pi-pi-intensity interferometry are reported for collisions of Ar+KCl at 1.76A GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The experimental correlation functions as a function of the relative momentum are compared to model calculations allowing the determination of the space-time extent of the corresponding emission sources. The pp source radii are found significantly larger than the pp emission radius. The present radii do well complement the beam-energy dependences of Gaussian source radii of the collision system of size A + A similar or equal to 40 + 40. The pp source radius at fixed beam energy is found to increase linearly with the cube root of the number of participants. From this trend, a lower limit of the pp correlation radius is deduced.  
  Address [Finocchiaro, P.] Ist Nazl Fis Nucl, Lab Nazl Sud, I-95125 Catania, Italy, Email: kotte@fzd.de  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1434-6001 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000291659900005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 658  
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Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. url  doi
openurl 
  Title Lambda-p femtoscopy in collisions of Ar + KCl at 1.76AGeV Type Journal Article
  Year 2010 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 82 Issue 2 Pages 021901 - 5pp  
  Keywords  
  Abstract Results on Lambda p femtoscopy are reported at the lowest energy so far. At a beam energy of 1.76AGeV, the reaction Ar + KCl was studied with the High Acceptance Di-Electron Spectrometer ( HADES) at SIS18/GSI. A high-statistics and high-purity Lambda sample was collected, allowing for the investigation of Lambda p correlations at low relative momenta. The experimental correlation function is compared to corresponding model calculations allowing the determination of the space-time extent of the Lambda p emission source. The Lambda p source radius is found to be slightly smaller than the pp correlation radius for a similar collision system. The present Lambda p radius is significantly smaller than that found for Au + Au/Pb + Pb collisions in the AGS, SPS, and RHIC energy domains but larger than that observed for electroproduction from He. Taking into account all available data, we find the Lambda p source radius to increase almost linearly with the number of participants to the power of one-third.  
  Address [Finocchiaro, P.] Ist Nazl Fis Nucl, Lab Nazl Sud, I-95125 Catania, Italy, Email: kotte@fzd.de  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0556-2813 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000281017300001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 393  
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Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. url  doi
openurl 
  Title In-medium effects on K-0 mesons in relativistic heavy-ion collisions Type Journal Article
  Year 2010 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 82 Issue 4 Pages 044907 - 9pp  
  Keywords  
  Abstract We present the transverse momentum spectra and rapidity distributions of pi(-) and K-S(0) in Ar + KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the High Acceptance Di-Electron Spectrometer (HADES). The reconstructed K-S(0) sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental pi(-) and K-S(0) distributions to predictions by the Isospin Quantum Molecular Dynamics (IQMD) model. The model calculations show that K-S(0) at low transverse momenta constitute a particularly well-suited tool to investigate the kaon in-medium potential. Our K-S(0) data suggest a strong repulsive in-medium K-0 potential of about 40 MeV strength.  
  Address [Agakishiev, G.; Destefanis, M.; Gilardi, C.; Kirschner, D.; Kuehn, W.; Lange, J. S.; Metag, V.; Mishra, D.; Pechenov, V.; Pechenova, O.; Cavalcanti, T. Perez; Spataro, S.; Spruck, B.] Univ Giessen, Inst Phys 2, D-35392 Giessen, Germany, Email: laura.fabbietti@ph.tum.de  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0556-2813 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000283648400009 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 334  
Permanent link to this record
 

 
Author (up) HADES Collaboration (Agakishiev, G. et al); Diaz, J.; Gil, A. url  doi
openurl 
  Title Origin of the low-mass electron pair excess in light nucleus-nucleus collisions Type Journal Article
  Year 2010 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 690 Issue 2 Pages 118-122  
  Keywords Virtual bremsstrahlung; Dileptons; Nucleon-nucleon collisions  
  Abstract We report measurements of electron pair production in elementary p + p and d + p reactions at 1.25 GeV/mu with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n + p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass Me+e- > 0.15 GeV/c(2) is about an order of magnitude larger in n + p reactions as compared to p + p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C + C reactions are compatible with a superposition of elementary n + p and p + p collisions, leaving little room for additional electron pair sources in such light collision systems.  
  Address [Froehlich, I.; Galatyuk, T.; Goebel, K.; Lorenz, M.; Markert, J.; Michel, J.; Muentz, C.; Pachmayer, Y. C.; Stroebele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.] Goethe Univ Frankfurt, Inst Kernphys, D-60438 Frankfurt, Germany, Email: t.galatyuk@gsi.de  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000279513800003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 413  
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