Papers - MATSUDA Tatsuro
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Double spin asymmetry in exclusive ρ0 muoproduction at COMPASS Reviewed
P. Abbon, E. Albrecht, T. Matsuda et al.
European Physical Journal C 52 ( 2 ) 255 - 265 2007.10
Language：English Publishing type：Research paper (scientific journal)
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Measurement of the #Eγ(/)→#ERp→K+Λ reaction at backward angles Reviewed
W.C. Chang, K. Horie, T. Matsuda et al.
Physical Review C 76 ( 4 ) 042201 - 6 2007.10
Language：English Publishing type：Research paper (scientific journal)
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Double spin asymmetry in exclusive ρ<sup>0</sup> muoproduction at COMPASS
Alekseev M., Alexakhin V., Alexandrov Y., Alexeev G., Amoroso A., Arbuzov A., Badełek B., Balestra F., Ball J., Baum G., Barth J., Bedfer Y., Bernet C., Bertini R., Bettinelli M., Birsa R., Bisplinghoff J., Bordalo P., Bradamante F., Bravar A., Bressan A., Brona G., Burtin E., Bussa M., Chapiro A., Chiosso M., Cicuttin A., Colantoni M., Costa S., Crespo M., D'Hose N., Dalla Torre S., Das S., Dasgupta S., De Masi R., Dedek N., Denisov O., Dhara L., Diaz V., Dinkelbach A., Donskov S., Dorofeev V., Doshita N., Duic V., Dünnweber W., Eversheim P., Eyrich W., Fabro M., Faessler M., Falaleev V., Ferrero A., Ferrero L., Finger M., Finger M., Fischer H., Franco C., Franz J., Friedrich J., Frolov V., Garfagnini R., Gautheron F., Gavrichtchouk O., Gazda R., Gerassimov S., Geyer R., Giorgi M., Gobbo B., Goertz S., Gorin A., Grabmüller S., Grajek O., Grasso A., Grube B., Gushterski R., Guskov A., Haas F., Hannappel J., Von Harrach D., Hasegawa T., Heckmann J., Hedicke S., Heinsius F., Hermann R., Heß C., Hinterberger F., Von Hodenberg M., Horikawa N., Horikawa S., Ilgner C., Ioukaev A., Ishimoto S., Ivanov O., Ivanshin Y., Iwata T.
European Physical Journal C 52 ( 2 ) 255 - 265 2007.10
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：European Physical Journal C
The longitudinal double spin asymmetry A 1 ρ for exclusive leptoproduction of ρ 0 mesons, μ+N→μ+N+ρ, is studied using the COMPASS 2002 and 2003 data. The measured reaction is incoherent exclusive ρ 0 production on polarised deuterons. The Q 2 and x dependence of A 1 ρ is presented in a wide kinematical range, 3×10 -3 < Q 2 < 7 (GeV/c) 2 and 5×10 -5 < x < 0.05. The results presented are the first measurements of A 1 ρ at small Q 2 (Q 2 < 0.1 (GeV/c) 2 ) and small x (x < 3×10 -3 ). The asymmetry is in general compatible with zero in the whole kinematical range. © 2007 Springer-Verlag / Società Italiana di Fisica.
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The COMPASS experiment at CERN Reviewed
Abbon P., Albrecht E., Alexakhin V., Alexandrov Y., Alexeev G., Alekseev M., Amoroso A., Angerer H., Anosov V., Badełek B., Balestra F., Ball J., Barth J., Baum G., Becker M., Bedfer Y., Berglund P., Bernet C., Bertini R., Bettinelli M., Birsa R., Bisplinghoff J., Bordalo P., Bosteels M., Bradamante F., Braem A., Bravar A., Bressan A., Brona G., Burtin E., Bussa M., Bytchkov V., Chalifour M., Chapiro A., Chiosso M., Ciliberti P., Cicuttin A., Colantoni M., Colavita A., Costa S., Crespo M., Cristaudo P., Dafni T., d'Hose N., Dalla Torre S., d'Ambrosio C., Das S., Dasgupta S., Delagnes E., De Masi R., Deck P., Dedek N., Demchenko D., Denisov O., Dhara L., Diaz V., Dibiase N., Dinkelbach A., Dolgopolov A., Donati A., Donskov S., Dorofeev V., Doshita N., Durand D., Duic V., Dünnweber W., Efremov A., Eversheim P., Eyrich W., Faessler M., Falaleev V., Fauland P., Ferrero A., Ferrero L., Finger M., Finger M., Fischer H., Franco C., Franz J., Fratnik F., Friedrich J., Frolov V., Fuchs U., Garfagnini R., Gatignon L., Gautheron F., Gavrichtchouk O., Gerassimov S., Geyer R., Gheller J., Giganon A., Giorgi M., Gobbo B.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 577 ( 3 ) 455 - 518 2007.7
Language：English Publishing type：Research paper (scientific journal) Publisher：Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The COMPASS experiment makes use of the CERN SPS high-intensity muon and hadron beams for the investigation of the nucleon spin structure and the spectroscopy of hadrons. One or more outgoing particles are detected in coincidence with the incoming muon or hadron. A large polarised target inside a superconducting solenoid is used for the measurements with the muon beam. Outgoing particles are detected by a two-stage, large angle and large momentum range spectrometer. The setup is built using several types of tracking detectors, according to the expected incident rate, required space resolution and the solid angle to be covered. Particle identification is achieved using a RICH counter and both hadron and electromagnetic calorimeters. The setup has been successfully operated from 2002 onwards using a muon beam. Data with a hadron beam were also collected in 2004. This article describes the main features and performances of the spectrometer in 2004; a short summary of the 2006 upgrade is also given. © 2007 Elsevier B.V. All rights reserved.
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The COMPASS experiment at CERN Reviewed
P. Abbon, E. Albrecht, T. Matsuda et al.
Nuclear Instruments and Methods A 577 455 - 518 2007.7
Language：English Publishing type：Research paper (scientific journal)
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Alexakhin V., Alexandrov Y., Alexeev G., Amoroso A., Badełek B., Balestra F., Ball J., Baum G., Bedfer Y., Bernet C., Bertini R., Birsa R., Bisplinghoff J., Bordalo P., Bradamante F., Bravar A., Bressan A., Brona G., Burtin E., Bussa M., Chapiro A., Cicuttin A., Colantoni M., Costa S., Crespo M., d'Hose N., Dalla Torre S., Dasgupta S., De Masi R., Denisov O., Dhara L., Diaz Kavka V., Dinkelbach A., Donskov S., Dorofeev V., Doshita N., Duic V., Dünnweber W., Eversheim P., Eyrich W., Fabro M., Faessler M., Falaleev V., Ferrero A., Ferrero L., Finger M., Finger M., Fischer H., Franz J., Friedrich J., Frolov V., Garfagnini R., Gautheron F., Gavrichtchouk O., Gerassimov S., Geyer R., Giorgi M., Gobbo B., Goertz S., Gorin A., Grajek O., Grasso A., Grube B., Hannappel J., von Harrach D., Hasegawa T., Heckmann J., Hedicke S., Heinsius F., Hermann R., Heß C., Hinterberger F., von Hodenberg M., Horikawa N., Horikawa S., Ilgner C., Ioukaev A., Ishimoto S., Ivanov O., Iwata T., Jahn R., Janata A., Joosten R., Jouravlev N., Kabuß E., Kang D., Ketzer B., Khaustov G., Khokhlov Y., Khomutov N., Kisselev Y., Klein F., Koblitz S., Koivuniemi J., Kolosov V., Komissarov E., Kondo K.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 647 ( 5-6 ) 330 - 340 2007.4
Language：English Publishing type：Research paper (scientific journal) Publisher：Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
We present a precise measurement of the deuteron longitudinal spin asymmetry A 1 d and of the deuteron spin-dependent structure function g 1 d at Q 2 < 1 (GeV / c) 2 and 4 × 10 -5 < x < 2.5 × 10 -2 based on the data collected by the COMPASS experiment at CERN during the years 2002 and 2003. The statistical precision is tenfold better than that of the previous measurement in this region. The measured A 1 d and g 1 d are found to be consistent with zero in the whole range of x. © 2007 Elsevier B.V. All rights reserved.
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Spin asymmetry A1d and the spin-dependent structure function g1d of the deuteron at low values of x and Q2. Reviewed
Yu. Alexakhin, Yu. Alexandrov, T. Matsuda et al.
Physics Letters B 647 330 - 340 2007.4
Language：English Publishing type：Research paper (scientific journal)
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The deuteron spin-dependent structure function g<inf>1</inf><sup>d</sup> and its first moment Reviewed
Alexakhin V., Alexandrov Y., Alexeev G., Alexeev M., Amoroso A., Badełek B., Balestra F., Ball J., Barth J., Baum G., Becker M., Bedfer Y., Bernet C., Bertini R., Bettinelli M., Birsa R., Bisplinghoff J., Bordalo P., Bradamante F., Bressan A., Brona G., Burtin E., Bussa M., Bytchkov V., Chapiro A., Cicuttin A., Colantoni M., Colavita A., Costa S., Crespo M., d'Hose N., Dalla Torre S., Das S., Dasgupta S., De Masi R., Dedek N., Demchenko D., Denisov O., Dhara L., Diaz V., Dinkelbach A., Donskov S., Dorofeev V., Doshita N., Duic V., Dünnweber W., Efremov A., Eversheim P., Eyrich W., Faessler M., Fauland P., Ferrero A., Ferrero L., Finger M., Finger M., Fischer H., Franz J., Friedrich J., Frolov V., Garfagnini R., Gautheron F., Gavrichtchouk O., Gerassimov S., Geyer R., Giorgi M., Gobbo B., Goertz S., Gorin A., Grajek O., Grasso A., Grube B., Guskov A., Haas F., Hannappel J., von Harrach D., Hasegawa T., Hedicke S., Heinsius F., Hermann R., Heß C., Hinterberger F., von Hodenberg M., Horikawa N., Horikawa S., Horn I., Ilgner C., Ioukaev A., Ivanchin I., Ivanov O., Iwata T., Jahn R., Janata A., Joosten R., Jouravlev N.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 647 ( 1 ) 8 - 17 2007.3
Language：English Publishing type：Research paper (scientific journal) Publisher：Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
We present a measurement of the deuteron spin-dependent structure function g 1 d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Γ 1 d , the first moment of g 1 d (x), and for the matrix element of the singlet axial current, a 0 . The results of QCD fits in the next to leading order (NLO) on all g 1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function ΔG positive or negative, which describe the data equally well. In both cases, at Q 2 = 3 (GeV / c) 2 the first moment of Δ G (x) is found to be of the order of 0.2-0.3 in absolute value. © 2007 Elsevier B.V. All rights reserved.
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A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target
Ageev E., Alexakhin V., Alexandrov Y., Alexeev G., Alexeev M., Amoroso A., Badełek B., Balestra F., Ball J., Barth J., Baum G., Becker M., Bedfer Y., Berglund P., Bernet C., Bertini R., Bettinelli M., Birsa R., Bisplinghoff J., Bordalo P., Bradamante F., Bressan A., Brona G., Burtin E., Bussa M., Bytchkov V., Chapiro A., Cicuttin A., Colantoni M., Colavita A., Costa S., Crespo M., d'Hose N., Dalla Torre S., Das S., Dasgupta S., De Masi R., Dedek N., Demchenko D., Denisov O., Dhara L., Diaz V., Dinkelbach A., Donskov S., Dorofeev V., Doshita N., Duic V., Dünnweber W., Efremov A., Eversheim P., Eyrich W., Faessler M., Falaleev V., Fauland P., Ferrero A., Ferrero L., Finger M., Finger M., Fischer H., Franz J., Friedrich J., Frolov V., Fuchs U., Garfagnini R., Gautheron F., Gavrichtchouk O., Gerassimov S., Geyer R., Giorgi M., Gobbo B., Goertz S., Gorin A., Grajek O., Grasso A., Grube B., Guskov A., Haas F., Hannappel J., von Harrach D., Hasegawa T., Hedicke S., Heinsius F., Hermann R., Heß C., Hinterberger F., von Hodenberg M., Horikawa N., Horikawa S., Horn I., Ilgner C., Ioukaev A., Ishimoto S., Ivanchin I.
Nuclear Physics B 765 ( 1-2 ) 31 - 70 2007.3
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Nuclear Physics B
New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6 LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV / c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations. © 2006 Elsevier B.V. All rights reserved.
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The deuteron spin-dependent structure function g1d and its first moment Reviewed
Yu. Alexakhin, Yu. Alexandrov, T. Matsuda et al.
Physics Letters B 647 8 - 17 2007.3
Language：English Publishing type：Research paper (scientific journal)
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A New measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target Reviewed
E.S. Ageev, V.Yu. Alexakhin, T. Matsuda et al.
Nuclear Physics B 765 31 - 70 2007.3
Language：English Publishing type：Research paper (scientific journal)
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Differential cross section and photon-beam asymmetry for the γ→n→K+Σ- Reaction at Eγ=1.5-2.4GeV
Kohri H., Ahn D., Ahn J., Akimune H., Asano Y., Chang W., Date' S., Ejiri H., Fukui S., Fujimura H., Fujiwara M., Hasegawa S., Hicks K., Hotta T., Imai K., Ishikawa T., Iwata T., Kawai H., Kim Z., Kino K., Kumagai N., Makino S., Mart T., Matsuda T., Matsumura T., Matsuoka N., Mibe T., Miyabe M., Miyachi Y., Morita M., Muramatsu N., Nakano T., Niiyama M., Nomachi M., Ohashi Y., Ohkuma H., Ooba T., Oshuev D., Rangacharyulu C., Sakaguchi A., Sasaki T., Shagin P., Shiino Y., Shimizu A., Shimizu H., Sugaya Y., Sumihama M., Toi Y., Toyokawa H., Wakai A., Wang C., Wang S., Yonehara K., Yorita T., Yoshimura M., Yosoi M., Zegers R.
Physical Review Letters 97 ( 8 ) 2006.8
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Physical Review Letters
Differential cross sections and photon-beam asymmetries have been measured for the γ→n→K+Σ- and γ→p→K+Σ0 reactions separately using liquid deuterium and hydrogen targets with incident linearly polarized photon beams of Eγ=1.5-2.4GeV at 0. 6 < cos¡ΘcmK < 1. The cross section ratio of σK+Σ-/ σK+Σ0, expected to be 2 on the basis of the isospin 1/2 exchange, is found to be close to 1. For the K+Σ- reaction, large positive asymmetries are observed, indicating the dominance of K* exchange. The large difference between the asymmetries for the K+Σ- and K+Σ0 reactions cannot be explained by simple theoretical considerations based on Regge model calculations. © 2006 The American Physical Society.
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Differential cross section and photon beam asymmetry for the #Eγ(/)→#ERn ---> K+Σ-- reaction at Eγ=1.5-2.4 GeV Reviewed
D.S. Ahn, J.K. Ahn, T. Matsuda et al.
Physical Review Letters 97 082003 - 5 2006.8
Language：English Publishing type：Research paper (scientific journal)
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Evidence for κ meson production in J/ψ → K̄*(892)<sup>0</sup>K<sup>+</sup>π- process
Ablikim M., Bai J., Ban Y., Bian J., Cai X., Chen H., Chen H., Chen H., Chen J., Chen J., Chen Y., Chi S., Chu Y., Cui X., Dai Y., Deng Z., Dong Q., Du S., Du Z., Fang J., Fang S., Fu C., Gao C., Gao Y., Gu S., Gu Y., Guo Y., Guo Y., Guo Z., Harris F., He K., He M., Heng Y., Hu H., Hu T., Huang G., Huang X., Huang X., Ishida M., Ishida S., Ji X., Jiang X., Jiao J., Jin D., Jin S., Jin Y., Komada T., Kurokawa S., Lai Y., Li G., Li H., Li H., Li J., Li R., Li S., Li W., Li W., Li X., Li X., Li Y., Liang Y., Liao H., Liu C., Liu F., Liu F., Liu H., Liu H., Liu J., Liu J., Liu J., Liu R., Liu Z., Lu F., Lu G., Lu H., Lu J., Luo C., Ma F., Ma H., Ma L., Ma Q., Ma X., Mao Z., Matsuda T., Mo X., Nie J., Peng H., Qi N., Qin H., Qiu J., Ren Z., Rong G., Shan L., Shang L., Shen D., Shen X., Sheng H., Shi F., Shi X.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 633 ( 6 ) 681 - 690 2006.2
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Based on 58 million BESII J/ψ events, the K̄*(892) 0 K + π - channel in K + K - π + π - is studied. A clear low mass enhancement in the invariant mass spectrum of K + π - is observed. The low mass enhancement does not come from background of other J/ψ decay channels, nor from phase space. Two independent partial wave analyses have been performed. Both analyses favor that the low mass enhancement is the κ, an iso-spinor scalar resonant state. The average mass and width of the κ in the two analyses are 878±23 -55 +64 MeV/c 2 and 499±52 -87 +55 MeV/c 2 , respectively, corresponding to a pole at (841±30 -73 +81 )-i(309±45 -72 +48 ) MeV/c 2 . © 2006 Elsevier B.V. All rights reserved.
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Gluon polarization in the nucleon from quasi-real photoproduction of high-p<inf>T</inf> hadron pairs
Ageev E., Alexakhin V., Alexandrov Y., Alexeev G., Amoroso A., Badelek B., Balestra F., Ball J., Baum G., Bedfer Y., Berglund P., Bernet C., Bertini R., Birsa R., Bisplinghoff J., Bordalo P., Bradamante F., Bravar A., Bressan A., Brona G., Burtin E., Bussa M., Bytchkov V., Cerini L., Chapiro A., Cicuttin A., Colantoni M., Colavita A., Costa S., Crespo M., Dalla Torre S., Dasgupta S., Dedek N., De Masi R., Denisov O., Dhara L., Diaz V., Dinkelbach A., Dolgopolov A., Donskov S., Dorofeev V., Doshita N., Duic V., Dünnweber W., Ehlers J., Eversheim P., Eyrich W., Fabro M., Faessler M., Falaleev V., Fauland P., Ferrero A., Ferrero L., Finger M., Finger M., Fischer H., Franz J., Friedrich J., Frolov V., Garfagnini R., Gautheron F., Gavrichtchouk O., Gerassimov S., Geyer R., Giorgi M., Gobbo B., Goertz S., Gorin A., Grajek O., Grasso A., Grube B., Grünemaier A., Hannappel J., Von Harrach D., Hasegawa T., Hedicke S., Heinsius F., Hermann R., Heß C., Hinterberger F., Von Hodenberg M., Horikawa N., Horikawa S., D'Hose N., Ijaduola R., Ilgner C., Ioukaev A., Ishimoto S.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 633 ( 1 ) 25 - 32 2006.2
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
We present a determination of the gluon polarization ΔG/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q 2 < 1 (GeV/c) 2 , with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6 LiD target. The helicity asymmetry for the selected events is 〈A∥/D〉=0.002±0.019(stat)±0.003(syst). From this value, we obtain in a leading-order QCD analysis ΔG/G=0.024±0. 089(stat)±0.057(syst) at x g =0.095 and μ2≃3 (GeV/c) 2 . © 2005 Elsevier B.V. All rights reserved.
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Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs. Reviewed
E.S. Ageev, V.Yu. Alexakhin, Yu. Alexandrov, G.D. Alexeev, A. Amoroso, T. Matsuda(118番目/202人)他196名
Physics Letters B 633 25 - 32 2006.2
Language：English Publishing type：Research paper (scientific journal)
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Evidence for κmeson production in J/ψ ---> anti-K* (892)0 K+ π- process.
M. Ablikim, J.Z. Bai, Y. Ban, J.G. Bian, T. Matsuda,(83番目/177人)他172名。
Physics Letters BVol. 633, pp.681-690 2006.2
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Near-threshold diffractive I-Meson photoproduction from the proton Reviewed
Mibe T., Chang W., Nakano T., Ahn D., Ahn J., Akimune H., Asano Y., Daté S., Ejiri H., Fujimura H., Fujiwara M., Hicks K., Hotta T., Imai K., Ishikawa T., Iwata T., Kawai H., Kim Z., Kino K., Kohri H., Kumagai N., Makino S., Matsuda T., Matsumura T., Matsuoka N., Miwa K., Miyabe M., Miyachi Y., Morita M., Muramatsu N., Niiyama M., Nomachi M., Ohashi Y., Ooba T., Ohkuma H., Oshuev D., Rangacharyulu C., Sakaguchi A., Sasaki T., Shagin P., Shiino Y., Shimizu H., Sugaya Y., Sumihama M., Titov A., Toi Y., Toyokawa H., Wakai A., Wang C., Wang S., Yonehara K., Yorita T., Yoshimura M., Yosoi M., Zegers R.
Physical Review Letters 95 ( 18 ) 2005.10
Language：English Publishing type：Research paper (scientific journal) Publisher：Physical Review Letters
Photoproduction of a I meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to Eγ=2.37GeV. The differential cross sections at t=-|t|min do not increase smoothly as Eγ increases but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that I mesons are photoproduced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes. © 2005 The American Physical Society.
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Diffractive φ-meson photoproduction on the proton near threshold
T. Mibe, W.C. Chang, T. Nakano , D.S. Ahn, J.K. Ahn, H. Akimune, Y. Asano, T. Matsuda(23番目/55人)他47名
Physical Review Vol. 95, 182001. 2005.10
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Intermediate resonance excitation in the γp→pπ <sup>0</sup>π<sup>0</sup> reaction
Ahrens J., Altieri S., Annand J., Anton G., Arends H., Aulenbacher K., Beck R., Bradtke C., Braghieri A., Degrande N., D'Hose N., Dutz H., Goertz S., Grabmayr P., Hansen K., Harmsen J., Von Harrach D., Hasegawa S., Hasegawa T., Heid E., Helbing K., Holvoet H., Van Hoorebeke L., Horikawa N., Iwata T., Jahn O., Jennewein P., Kageya T., Kiel B., Klein F., Kondratiev R., Kossert K., Krimmer J., Lang M., Lannoy B., Leukel R., Lisin V., Matsuda T., McGeorge J., Meier A., Menze D., Meyer W., Michel T., Naumann J., Panzeri A., Pedroni P., Pinelli T., Preobrajenski I., Radtke E., Reichert E., Reicherz G., Rohlof C., Rosner G., Rostomyan T., Ryckbosch D., Sauer M., Schoch B., Schumacher M., Seitz B., Speckner T., Takabayashi N., Tamas G., Thomas A., Van De Vyver R., Wakai A., Weihofen W., Wissmann F., Zapadtka F., Zeitler G.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 624 ( 3-4 ) 173 - 180 2005.9
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
The helicity dependence of the total cross section for the γ→p→→pπ0π0 reaction has been measured for the first time at incident photon energies from 400 to 800 MeV. The measurement, performed at the tagged photon beam facility of the MAMI accelerator in Mainz, used the large acceptance detector DAPHNE and a longitudinally polarized frozen-spin target. This channel is found to be excited predominantly when the photon and proton have a parallel spin orientation, most likely due to the intermediate production of the D13(1520) resonance. However, the contribution of the antiparallel spin configuration, arising from other reaction mechanisms, is also not negligible. This result gives important new information to resolve the existing model discrepancies in the identification of the nucleon resonances contributing to this channel. © 2005 Elsevier B.V. All rights reserved.