Isospin decomposition of the basic double-pionic fusion in the region of the ABC effect

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• 作者：WASA-at-COSY Collaboration P. Adlarson^aW. Augustyniak^bW. Bardan^cM. Bashkanov^dT. Bednarski^cF.S. Bergmann^eM. Ber?owski^fH. Bhatt^gM. Bü ; scher^h ; ⁱH. Calé ; n^aH. Clement^d ; ^{clement@pit.physik.uni-tuebingen.de}D. Coderre^h ; ⁱ ; ^jE. Czerwi¨½ski^cK. Demmich^eE. Doroshkevich^dR. Engels^h ; ⁱW. Erven^k ; ⁱW. Eyrich^lP. Fedorets^h ; ⁱ ; ^mK. Fö ; hlⁿK. Fransson^aF. Goldenbaum^h ; ⁱP. Goslawski^eA. Goswami^oK. Grigoryev^h ; ⁱ ; ^pC.-O. Gullströ ; m^aF. Hauenstein^lL. Heijkenskjö ; ld^aV. Hejny^h ; ⁱF. Hinterberger^qM. Hodana^c ; ^h ; ⁱB. Hö ; istad^aA. Jany^cB.R. Jany^cL. Jarczyk^cT. Johansson^aB. Kamys^cG. Kemmerling^k ; ⁱF.A. Khan^h ; ⁱA. Khoukaz^eS. Kistryn^cJ. Klaja^cH. Kleines^k ; ⁱB. K?os^rM. Krapp^lW. Krzemie¨½^cP. Kulessa^sA. Kup??^a ; ^fK. Lalwani^gD. Lersch^h ; ⁱL. Li^lB. Lorentz^h ; ⁱA. Magiera^cR. Maier^h ; ⁱP. Marciniewski^aB. Maria¨½ski^bM. Mikirtychiants^h ; ⁱ ; ^j ; ^pH.-P. Morsch^bP. Moskal^cB.K. Nandi^gS. Nied?wiecki^cH. Ohm^h ; ⁱI. Ozerianska^cE. Perez del Rio^dP. Pluci¨½ski^a ; ¹P. Podkopa?^c ; ^h ; ⁱD. Prasuhn^h ; ⁱA. Pricking^dD. Pszczel^a ; ^fK. Pysz^sA. Pyszniak^a ; ^cC.F. Redmer^a ; ²J. Ritman^h ; ⁱ ; ^jA. Roy^oZ. Rudy^cS. Sawant^gS. Schadmand^h ; ⁱA. Schmidt^lT. Sefzick^h ; ⁱV. Serdyuk^h ; ⁱ ; ^tN. Shah^g ; ³M. Siemaszko^rR. Siudak^sT. Skorodko^dM. Skurzok^cJ. Smyrski^cV. Sopov^mR. Stassen^h ; ⁱJ. Stepaniak^fE. Stephan^rG. Sterzenbach^h ; ⁱH. Stockhorst^h ; ⁱH. Strö ; her^h ; ⁱA. Szczurek^sT. Tolba^h ; ⁱ ; ⁴A. Trzci¨½ski^bR. Varma^gP. Vlasov^qG.J. Wagner^dW. W?glorz^rM. Wolke^aA. Wro¨½ska^cP. Wü ; stner^k ; ⁱP. Wurm^h ; ⁱA. Yamamoto^uX. Yuan^vL. Yurev^t ; ⁵J. Zabierowski^wC. Zheng^vM.J. Zieli¨½ski^cW. Zipper^rJ. Z?oma¨½czuk^aP. ?upra¨½ski^bM. ?urek^caDivision of Nuclear Physics ; Department of Physics ; Astronomy ; Uppsala University ; Box 516 ; 75120 Uppsala ; SwedenDivision of Nuclear PhysicsDepartment of Physics ; AstronomyUppsala UniversityBox 516Uppsala75120Sweden^bDepartment of Nuclear Physics ; National Centre for Nuclear Research ; ul. Hoza 69 ; 00-681 ; Warsaw ; PolandDepartment of Nuclear PhysicsNational Centre for Nuclear Researchul. Hoza 69Warsaw00-681Poland^cInstitute of Physics ; Jagiellonian University ; ul. Reymonta 4 ; 30-059 Krakó ; w ; PolandInstitute of PhysicsJagiellonian Universityul. Reymonta 4Krakó ; w30-059Poland^dPhysikalisches Institut ; Eberhard-Karls-Universit&auml ; t Tü ; bingen ; Auf der Morgenstelle 14 ; 72076 Tü ; bingen ; GermanyPhysikalisches InstitutEberhard-Karls-Universit&auml ; t Tü ; bingenAuf der Morgenstelle 14Tü ; bingen72076Germany^eInstitut fü ; r Kernphysik ; Westf&auml ; lische Wilhelms-Universit&auml ; t Mü ; nster ; Wilhelm-Klemm-Str. 9 ; 48149 Mü ; nster ; GermanyInstitut fü ; r KernphysikWestf&auml ; lische Wilhelms-Universit&auml ; t Mü ; nsterWilhelm-Klemm-Str. 9Mü ; nster48149Germany^fHigh Energy Physics Department ; National Centre for Nuclear Research ; ul. Hoza 69 ; 00-681 ; Warsaw ; PolandHigh Energy Physics DepartmentNational Centre for Nuclear Researchul. Hoza 69Warsaw00-681Poland^gDepartment of Physics ; Indian Institute of Technology Bombay Powai ; Mumbai ; 400076 ; Maharashtra ; IndiaDepartment of PhysicsIndian Institute of Technology Bombay PowaiMumbaiMaharashtra400076India^hInstitut fü ; r Kernphysik ; Forschungszentrum Jü ; lich ; 52425 Jü ; lich ; GermanyInstitut fü ; r KernphysikForschungszentrum Jü ; lichJü ; lich52425GermanyⁱJü ; lich Center for Hadron Physics ; Forschungszentrum Jü ; lich ; 52425 Jü ; lich ; GermanyJü ; lich Center for Hadron PhysicsForschungszentrum Jü ; lichJü ; lich52425Germany^jInstitut fü ; r Experimentalphysik I ; Ruhr-Universit&auml ; t Bochum ; Universit&auml ; tsstr. 150 ; 44780 Bochum ; GermanyInstitut fü ; r Experimentalphysik IRuhr-Universit&auml ; t BochumUniversit&auml ; tsstr. 150Bochum44780Germany^kZentralinstitut fü ; r Elektronik ; Forschungszentrum Jü ; lich ; 52425 Jü ; lich ; GermanyZentralinstitut fü ; r ElektronikForschungszentrum Jü ; lichJü ; lich52425Germany^lPhysikalisches Institut ; Friedrich-Alexander-Universit&auml ; t Erlangen-Nü ; rnberg ; Erwin-Rommel-Str. 1 ; 91058 Erlangen ; GermanyPhysikalisches InstitutFriedrich-Alexander-Universit&auml ; t Erlangen-Nü ; rnbergErwin-Rommel-Str. 1Erlangen91058Germany^mInstitute for Theoretical ; Experimental Physics ; State Scientific Center of the Russian Federation ; Bolshaya Cheremushkinskaya 25 ; 117218 Moscow ; RussiaInstitute for Theoretical ; Experimental PhysicsState Scientific Center of the Russian FederationBolshaya Cheremushkinskaya 25Moscow117218RussiaⁿII. Physikalisches Institut ; Justus-Liebig-Universit&auml ; t Gieß ; en ; Heinrich-Buff-Ring 16 ; 35392 Giessen ; GermanyII. Physikalisches InstitutJustus-Liebig-Universit&auml ; t Gieß ; enHeinrich-Buff-Ring 16Giessen35392Germany^oDepartment of Physics ; Indian Institute of Technology Indore ; Khandwa Road ; Indore ; 452017 ; Madhya Pradesh ; IndiaDepartment of PhysicsIndian Institute of Technology IndoreKhandwa RoadIndoreMadhya Pradesh452017India^pHigh Energy Physics Division ; Petersburg Nuclear Physics Institute ; Orlova Rosha 2 ; 188300 Gatchina ; RussiaHigh Energy Physics DivisionPetersburg Nuclear Physics InstituteOrlova Rosha 2Gatchina188300Russia^qHelmholtz-Institut fü ; r Strahlen- und Kernphysik ; Rheinische Friedrich-Wilhelms-Universit&auml ; t Bonn ; Nuß ; allee 14&ndash ; 16 ; 53115 Bonn ; GermanyHelmholtz-Institut fü ; r Strahlen- und KernphysikRheinische Friedrich-Wilhelms-Universit&auml ; t BonnNuß ; allee 14&ndash ; 16Bonn53115Germany^rAugust Che?kowski Institute of Physics ; University of Silesia ; Uniwersytecka 4 ; 40-007 ; Katowice ; PolandAugust Che?kowski Institute of PhysicsUniversity of SilesiaUniwersytecka 4Katowice40-007Poland^sThe Henryk Niewodnicza¨½ski Institute of Nuclear Physics ; Polish Academy of Sciences ; 152 Radzikowskiego St. ; 31-342 Krakó ; w ; PolandThe Henryk Niewodnicza¨½ski Institute of Nuclear PhysicsPolish Academy of Sciences152 Radzikowskiego St.Krakó ; w31-342Poland^tDzhelepov Laboratory of Nuclear Problems ; Joint Institute for Nuclear Physics ; Joliot-Curie 6 ; 141980 Dubna ; RussiaDzhelepov Laboratory of Nuclear ProblemsJoint Institute for Nuclear PhysicsJoliot-Curie 6Dubna141980Russia^uHigh Energy Accelerator Research Organisation KEK ; Tsukuba ; Ibaraki 305-0801 ; JapanHigh Energy Accelerator Research Organisation KEKTsukubaIbaraki305-0801Japan^vInstitute of Modern Physics ; Chinese Academy of Sciences ; 509 Nanchang Rd. ; 730000 Lanzhou ; ChinaInstitute of Modern PhysicsChinese Academy of Sciences509 Nanchang Rd.Lanzhou730000China^wDepartment of Cosmic Ray Physics ; National Centre for Nuclear Research ; ul. Uniwersytecka 5 ; 90-950 ?ó ; d? ; PolandDepartment of Cosmic Ray PhysicsNational Centre for Nuclear Researchul. Uniwersytecka 5?ó ; d?90-950Poland^?Corresponding author.¹Present address ; Department of Physics ; Stockholm University ; Roslagstullsbacken 21 ; AlbaNova ; 10691 Stockholm ; Sweden.²Present address ; Institut fü ; r Kernphysik ; Johannes Gutenberg-Universit&auml ; t Mainz ; Johann-Joachim-Becher Weg 45 ; 55128 Mainz ; Germany.³Present address ; Department of Physics ; Astronomy ; University of California ; Los Angeles ; CA 90045 ; USA.⁴Present address ; Albert Einstein Center for Fundamental Physics ; Fachbereich Physik und Astronomie ; Universit&auml ; t Bern ; Sidlerstr. 5 ; 3012 Bern ; Switzerland.⁵Present address ; Department of Physics ; Astronomy ; University of Sheffield ; Hounsfield Road ; Sheffield ; S3 7RH ; United Kingdom.
• 关键词：ABC effect and resonance structure ; Double pion production ; Isospin decomposition
• 刊名：Physics Letters B
• 出版年：2013
• 出版时间：25 April, 2013
• 年：2013
• 卷：721
• 期：4-5
• 页码：229-236
• 全文大小：530 K

文摘

Exclusive and kinematically complete high-statistics measurements of the basic double-pionic fusion reactions , and have been carried out simultaneously over the energy region of the ABC effect using the WASA detector setup at COSY. Whereas the isoscalar reaction part given by the channel exhibits the ABC effect, i.e. a low-mass enhancement in the ¦Ð¦Ð-invariant mass distribution, as well as the associated resonance structure in the total cross section, the isovector part given by the channel shows a smooth behavior consistent with the conventional t-channel ¦¤¦¤ process. The data are very well reproduced by combining the data for isovector and isoscalar contributions, if the kinematical consequences of the isospin violation due to different masses for charged and neutral pions are taken into account.