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24 results on '"W. Dünnweber"'

1. First Measurement of Chiral Dynamics inπ−γ→π−π−π+

Author

C. Adolph, M. G. Alekseev, V. Yu. Alexakhin, Yu. Alexandrov, G. D. Alexeev, A. Amoroso, A. A. Antonov, A. Austregesilo, B. Badełek, F. Balestra, J. Barth, G. Baum, Y. Bedfer, J. Bernhard, R. Bertini, M. Bettinelli, K. A. Bicker, R. Birsa, J. Bisplinghoff, P. Bordalo, F. Bradamante, C. Braun, A. Bravar, A. Bressan, E. Burtin, D. Chaberny, M. Chiosso, S. U. Chung, A. Cicuttin, M. L. Crespo, S. Dalla Torre, S. Das, S. S. Dasgupta, O. Yu. Denisov, L. Dhara, S. V. Donskov, N. Doshita, V. Duic, W. Dünnweber, M. Dziewiecki, A. Efremov, C. Elia, P. D. Eversheim, W. Eyrich, M. Faessler, A. Ferrero, A. Filin, M. Finger, H. Fischer, C. Franco, N. du Fresne von Hohenesche, J. M. Friedrich, R. Garfagnini, F. Gautheron, O. P. Gavrichtchouk, R. Gazda, S. Gerassimov, R. Geyer, M. Giorgi, I. Gnesi, B. Gobbo, S. Goertz, S. Grabmüller, A. Grasso, B. Grube, R. Gushterski, A. Guskov, F. Haas, D. von Harrach, T. Hasegawa, F. H. Heinsius, F. Herrmann, C. Hess, F. Hinterberger, N. Horikawa, Ch. Höppner, N. d’Hose, S. Huber, S. Ishimoto, O. Ivanov, Yu. Ivanshin, T. Iwata, R. Jahn, P. Jasinski, G. Jegou, R. Joosten, E. Kabuss, D. Kang, B. Ketzer, G. V. Khaustov, Yu. A. Khokhlov, Yu. Kisselev, F. Klein, K. Klimaszewski, S. Koblitz, J. H. Koivuniemi, V. N. Kolosov, K. Kondo, K. Königsmann, I. Konorov, V. F. Konstantinov, A. Korzenev, A. M. Kotzinian, O. Kouznetsov, M. Krämer, Z. V. Kroumchtein, F. Kunne, K. Kurek, L. Lauser, A. A. Lednev, A. Lehmann, S. Levorato, J. Lichtenstadt, A. Maggiora, A. Magnon, N. Makke, G. K. Mallot, A. Mann, C. Marchand, A. Martin, J. Marzec, F. Massmann, T. Matsuda, W. Meyer, T. Michigami, Yu. V. Mikhailov, M. A. Moinester, A. Morreale, A. Mutter, A. Nagaytsev, T. Nagel, F. Nerling, S. Neubert, D. Neyret, V. I. Nikolaenko, W.-D. Nowak, A. S. Nunes, A. G. Olshevsky, M. Ostrick, A. Padee, R. Panknin, D. Panzieri, B. Parsamyan, S. Paul, E. Perevalova, G. Pesaro, D. V. Peshekhonov, G. Piragino, S. Platchkov, J. Pochodzalla, J. Polak, V. A. Polyakov, G. Pontecorvo, J. Pretz, C. Quintans, J.-F. Rajotte, S. Ramos, V. Rapatsky, G. Reicherz, A. Richter, E. Rocco, E. Rondio, N. S. Rossiyskaya, D. I. Ryabchikov, V. D. Samoylenko, A. Sandacz, M. G. Sapozhnikov, S. Sarkar, I. A. Savin, G. Sbrizzai, P. Schiavon, C. Schill, T. Schlüter, L. Schmitt, K. Schönning, S. Schopferer, W. Schröder, O. Yu. Shevchenko, H.-W. Siebert, L. Silva, L. Sinha, A. N. Sissakian, M. Slunecka, G. I. Smirnov, S. Sosio, F. Sozzi, A. Srnka, M. Stolarski, M. Sulc, R. Sulej, P. Sznajder, S. Takekawa, J. Ter Wolbeek, S. Tessaro, F. Tessarotto, A. Teufel, L. G. Tkatchev, S. Uhl, I. Uman, M. Vandenbroucke, M. Virius, N. V. Vlassov, R. Windmolders, W. Wiślicki, H. Wollny, K. Zaremba, M. Zavertyaev, E. Zemlyanichkina, M. Ziembicki, N. Zhuravlev, and A. Zvyagin

Subjects
Physics, Particle physics, Chiral perturbation theory, 010308 nuclear & particles physics, Partial wave analysis, General Physics and Astronomy, Order (ring theory), 7. Clean energy, 01 natural sciences, Nuclear physics, Momentum, Pion, 0103 physical sciences, Coulomb, Production (computer science), Nuclear Experiment, 010306 general physics, Primakoff effect
Abstract

The COMPASS collaboration at CERN has investigated the \pi^- \gamma -> \pi^- \pi^- \pi^+ reaction at center-of-momentum energy below five pion masses, sqrt(s) < 5 m(\pi), embedded in the Primakoff reaction of 190 GeV pions impinging on a lead target. Exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, t' < 0.001 (GeV/c)^2. Using partial-wave analysis techniques, the scattering intensity of Coulomb production described in terms of chiral dynamics and its dependence on the 3\pi-invariant mass m(3\pi) = sqrt(s) were extracted. The absolute cross section was determined in seven bins of $\sqrt{s}$ with an overall precision of 20%. At leading order, the result is found to be in good agreement with the prediction of chiral perturbation theory over the whole energy range investigated.

Published
2012

2. Observation of aJPC=1−+Exotic Resonance in Diffractive Dissociation of190 GeV/cπ−intoπ−π−π+

Author

M. G. Alekseev, V. Yu. Alexakhin, Yu. Alexandrov, G. D. Alexeev, A. Amoroso, A. Austregesilo, B. Badełek, F. Balestra, J. Ball, J. Barth, G. Baum, Y. Bedfer, J. Bernhard, R. Bertini, M. Bettinelli, R. Birsa, J. Bisplinghoff, P. Bordalo, F. Bradamante, A. Bravar, A. Bressan, G. Brona, E. Burtin, M. P. Bussa, A. Chapiro, M. Chiosso, S. U. Chung, A. Cicuttin, M. Colantoni, M. L. Crespo, S. Dalla Torre, T. Dafni, S. Das, S. S. Dasgupta, O. Yu. Denisov, L. Dhara, V. Diaz, A. M. Dinkelbach, S. V. Donskov, N. Doshita, V. Duic, W. Dünnweber, A. Efremov, A. El Alaoui, P. D. Eversheim, W. Eyrich, M. Faessler, A. Ferrero, M. Finger, H. Fischer, C. Franco, J. M. Friedrich, R. Garfagnini, F. Gautheron, O. P. Gavrichtchouk, R. Gazda, S. Gerassimov, R. Geyer, M. Giorgi, B. Gobbo, S. Goertz, S. Grabmüller, O. A. Grajek, A. Grasso, B. Grube, R. Gushterski, A. Guskov, F. Haas, D. von Harrach, T. Hasegawa, J. Heckmann, F. H. Heinsius, R. Hermann, F. Herrmann, C. Heß, F. Hinterberger, N. Horikawa, Ch. Höppner, N. d’Hose, C. Ilgner, S. Ishimoto, O. Ivanov, Yu. Ivanshin, T. Iwata, R. Jahn, P. Jasinski, G. Jegou, R. Joosten, E. Kabuß, D. Kang, B. Ketzer, G. V. Khaustov, Yu. A. Khokhlov, Yu. Kisselev, F. Klein, K. Klimaszewski, S. Koblitz, J. H. Koivuniemi, V. N. Kolosov, E. V. Komissarov, K. Kondo, K. Königsmann, R. Konopka, I. Konorov, V. F. Konstantinov, A. Korzenev, A. M. Kotzinian, O. Kouznetsov, K. Kowalik, M. Krämer, A. Kral, Z. V. Kroumchtein, R. Kuhn, F. Kunne, K. Kurek, L. Lauser, J. M. Le Goff, A. A. Lednev, A. Lehmann, S. Levorato, J. Lichtenstadt, T. Liska, A. Maggiora, M. Maggiora, A. Magnon, G. K. Mallot, A. Mann, C. Marchand, J. Marroncle, A. Martin, J. Marzec, F. Massmann, T. Matsuda, A. N. Maximov, W. Meyer, T. Michigami, Yu. V. Mikhailov, M. A. Moinester, A. Mutter, A. Nagaytsev, T. Nagel, J. Nassalski, T. Negrini, F. Nerling, S. Neubert, D. Neyret, V. I. Nikolaenko, A. G. Olshevsky, M. Ostrick, A. Padee, R. Panknin, D. Panzieri, B. Parsamyan, S. Paul, B. Pawlukiewicz-Kaminska, E. Perevalova, G. Pesaro, D. V. Peshekhonov, G. Piragino, S. Platchkov, J. Pochodzalla, J. Polak, V. A. Polyakov, G. Pontecorvo, J. Pretz, C. Quintans, J.-F. Rajotte, S. Ramos, V. Rapatsky, G. Reicherz, D. Reggiani, A. Richter, F. Robinet, E. Rocco, E. Rondio, D. I. Ryabchikov, V. D. Samoylenko, A. Sandacz, H. Santos, M. G. Sapozhnikov, S. Sarkar, I. A. Savin, G. Sbrizzai, P. Schiavon, C. Schill, T. Schlüter, L. Schmitt, S. Schopferer, W. Schröder, O. Yu. Shevchenko, H.-W. Siebert, L. Silva, L. Sinha, A. N. Sissakian, M. Slunecka, G. I. Smirnov, S. Sosio, F. Sozzi, A. Srnka, M. Stolarski, M. Sulc, R. Sulej, S. Takekawa, S. Tessaro, F. Tessarotto, A. Teufel, L. G. Tkatchev, S. Uhl, I. Uman, G. Venugopal, M. Virius, N. V. Vlassov, A. Vossen, Q. Weitzel, R. Windmolders, W. Wiślicki, H. Wollny, K. Zaremba, M. Zavertyaev, E. Zemlyanichkina, M. Ziembicki, J. Zhao, N. Zhuravlev, and A. Zvyagin

Subjects
Physics, Particle physics, 010308 nuclear & particles physics, Partial wave analysis, General Physics and Astronomy, Resonance, Parity (physics), Quantum number, 01 natural sciences, Dissociation (chemistry), Nuclear physics, Pion, 0103 physical sciences, Pi, COMPASS experiment, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics
Abstract

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the pi- pi- pi+ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1 GeV^2/c^2. The well-known resonances a1(1260), a2(1320), and pi2(1670) are clearly observed. In addition, the data show a significant natural parity exchange production of a resonance with spin-exotic quantum numbers J^PC = 1-+ at 1.66 GeV/c^2 decaying to rho pi. The resonant nature of this wave is evident from the mass-dependent phase differences to the J^PC = 2-+ and 1++ waves. From a mass-dependent fit a resonance mass of 1660 +- 10+0-64 MeV/c^2 and a width of 269+-21+42-64 MeV/c^2 is deduced.

Published
2010

3. Anisotropy of Yrast Gamma Transitions fromO16onTi48: Angular Momentum Dissipation and Alignment in Deep-Inelastic Reactions

Author

W. Trautmann, W. Dünnweber, H. Puchta, W. Hering, and C. Lauterbach

Subjects
Physics, Nuclear reaction, Angular momentum, Scattering, Q value, Yrast, General Physics and Astronomy, Atomic physics, Nuclear Experiment, Anisotropy, Energy (signal processing), Spectral line
Abstract

The intensities and angular correlations of yrast transitions measured in coincidence with light fragments from 96-MeV $^{16}\mathrm{O}$+$^{48}\mathrm{Ti}$ reactions are used to determine amount and alignment of the angular momentum transferred to the heavy fragment as a function of the reaction $Q$ value. It is found that fluctuations of the spin axis about the scattering normal are small at the most probable $Q$ value of - 32 MeV but increase strongly with increasing inelasticity.

Published
1979

4. Polarization, dynamics, and nonequilibrium complex-fragment emission

Author

T. K. Nayak, M. B. Tsang, C. K. Gelbke, J. Pochodzalla, Z. Chen, R. M. Ronningen, M. Tohyama, F. Zhu, W. G. Lynch, W. Dünnweber, and W. Trautmann

Subjects
Nuclear reaction, Physics, Photon, Mean field theory, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, Non-equilibrium thermodynamics, Atomic physics, Nuclear Experiment, Polarization (waves), Spectral line, Circular polarization
Abstract

The sign of the emission angle for nonequilibrium intermediate-mass fragments was determined from the circular polarization of coincident \ensuremath{\gamma} rays for $^{14}\mathrm{induced}$ reactions on $^{154}\mathrm{Sm}$ at E/A=35 MeV. Positive polarizations, ${P}_{\ensuremath{\gamma}}$\ensuremath{\le}0.3--0.4, are observed for fragments with 3\ensuremath{\le}Z\ensuremath{\le}6, consistent with fragment emission after deflection by the attractive nuclear mean field to negative emission angles. These polarizations are small compared to the trends established for nonequilibrium light particles and the expectations of simple dynamical production mechanisms.

Published
1988

5. Characteristics of Angular Momentum Relaxation inNe20+Er168Collisions at 13.5 MeV/u

Author

H. Puchta, W. Trautmann, C. Egelhaaf, R. Ritzka, W. Dünnweber, W. Trombik, and W. Hering

Subjects
Nuclear reaction, Nuclear physics, Physics, Angular momentum, Scattering, General Physics and Astronomy, Multiplicity (chemistry), Atomic physics, Nuclear Experiment, Anisotropy, Polarization (waves), Electromagnetic radiation, Circular polarization
Abstract

The multiplicity, anisotropy, and circular polarization of the ..gamma.. radiation from 270-MeV /sup 20/Ne+/sup 168/Er were measured in coincidence with the projectilelike fragments. The deduced angular momentum transfer in the deep-inelastic reaction component is rather small but can be understood, together with the fluctuations of the spin axis and the prevalence of negative-angle scattering, in terms of a frictional process in concurrence with breakup.

Published
1984

6. Tangential Friction in Deep-Inelastic Scattering ofO16from Nickel

Author

J.P. Wurm, H. Ho, R. Albrecht, G. Graw, S. G. Steadman, and W. Dünnweber

Subjects
Physics, Angular momentum, Spins, Q value, General Physics and Astronomy, chemistry.chemical_element, Dissipation, Deep inelastic scattering, Ion, Nickel, chemistry, Atomic physics, Multiplicity (chemistry), Nuclear Experiment
Abstract

Bombarding Ni targets with 96-MeV $^{16}\mathrm{O}$ ions, we have observed deep-inelastic groups of mass-16 and -12 reaction products with $Q$ values centered at -30 to - 35 MeV. From the multiplicity of the coincident $\ensuremath{\gamma}$ de-excitation, total fragment spins and hence, using a classical model, orbital angular momentum transfers of $12\ensuremath{\hbar}$ to $15\ensuremath{\hbar}$ are deduced. These, and at least 50% of the energy dissipation, are ascribed to tangential friction.

Published
1975

7. Correlated Spin Orientations inC12+C12Molecular Resonances

Author

R.S. Simon, W. Hennerici, W. Dünnweber, D. Konnerth, W. Trombik, V. Metag, W. Hering, Dietrich Habs, H. J. Hennrich, W. Zipper, A. Lazzarini, Roland Repnow, R. Kroth, and W. Trautmann

Subjects
Physics, Nuclear reaction, Isotope, Scattering, Stable isotope ratio, Carbon-12, General Physics and Astronomy, Parity (physics), Inelastic scattering, Molecular physics, Crystal Ball
Abstract

The correlation between the spin orientations of the two /sup 12/C(2/sup +/) nuclei in mutual inelastic /sup 12/C+ /sup 12/C scattering has been deduced from the directional correlations of the particle-coincident ..gamma.. rays measured with a crystal ball. Resonances in the cross section are found to be nearly uniquely associated with the mutually aligned component. The strong resonance structure as well as the characteristic behavior of the angular distributions of this reaction component are suggestive of the formation of a rotating dinuclear complex in the sticking configuration.

Published
1985

8. Ejectile Polarization in Heavy-Ion Reactions

Author

W. Dünnweber, W. Hering, W. Dahme, J.P. Wurm, H. Puchta, W. Kühn, W. Trautmann, and C. Lauterbach

Subjects
Nuclear reaction, Physics, Astrophysics::High Energy Astrophysical Phenomena, Excited state, Transmission method, General Physics and Astronomy, Heavy ion, Atomic physics, Nuclear Experiment, Polarization (waves), Excitation, Circular polarization, Spectral line
Abstract

Using the transmission method we have measured the circular polarization, ${P}_{\ensuremath{\gamma}}$, of $\ensuremath{\gamma}$ rays from excited projectilelike fragments in the reaction $^{16}\mathrm{O}$+$^{58}\mathrm{Ni}$ at 100 MeV. The polarizations are large with values up to $|{P}_{\ensuremath{\gamma}}|\ensuremath{\cong}100$%. Over the whole $Q$ range, the sign and magnitude of ${P}_{\ensuremath{\gamma}}$ can be interpreted in terms of matching conditions familiar from direct-reaction analysis, contrasting the statistical character of the associated heavy-fragment excitation.

Published
1981

9. Evidence for Negative Deflection Angles inAr40+ Ag Deep-Inelastic Reactions fromγ-Ray Circular Polarization Measurements

Author

G. Graw, H. Puchta, W. Trautmann, U. Lynen, R. Kopp, W. Dünnweber, J. de Boer, and C. Lauterbach

Subjects
Physics, Excited state, media_common.quotation_subject, Nuclear Theory, General Physics and Astronomy, Atomic physics, Nuclear Experiment, Asymmetry, Circular polarization, Ion, media_common
Abstract

We have measured the circular polarization of the deexcitation $\ensuremath{\gamma}$ rays following the bombardment of natural Ag targets with 284-MeV and 303-MeV $^{40}\mathrm{Ar}$ ions. A symmetric setup containing two polarimeters normal to the reaction plane was used. From the observed count-rate asymmetry of + 0.65%\ifmmode\pm\else\textpm\fi{}0.15% for deep-inelastic events we conclude that the excited product nuclei are polarized in the direction of the reaction normal ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}}_{i}\ifmmode\times\else\texttimes\fi{}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}}_{f}$ which provides evidence for a predominance of negative classical deflection angles.

Published
1977

10. Selective Parity Transitions and Dinuclear Orbiting ofC12+Mg24

Author

A. Glaesner, W. Zipper, J. Czakanski, R. Ritzka, D. Konnerth, W. Trombik, W. Dünnweber, and W. Hering

Subjects
Physics, Nuclear reaction, Particle properties, Q value, Nuclear Theory, General Physics and Astronomy, Coulomb barrier, Parity (physics), Atomic physics, Nuclear Experiment, Selectivity, Spectral line, Excitation
Abstract

In a spectroscopic study of the backward-angle yield from /sup 12/C+/sup 24/Mg at 3--4 times the Coulomb barrier, we find a strong preference for natural parity transitions in the excitation of close-to-yrast rotational bands. This selectivity is in strong quantitative disagreement with Hauser-Feshbach calculations for a compound-nuclear reaction and provides evidence for the conservation of the dinuclear parentage.

Published
1988

11. Observation of Spin Flip inC13+Mg24Inelastic Scattering

Author

S. Kubono, W. Dünnweber, C. Chasman, and P. D. Bond

Subjects
Nuclear reaction, Physics, education.field_of_study, Scattering, Population, General Physics and Astronomy, Spin-flip, State (functional analysis), Born approximation, Atomic physics, Inelastic scattering, Coupling (probability), education
Abstract

Evidence for spin-dependent interactions in heavy-ion reactions has been found in the inelastic scattering of 35-MeV $^{13}\mathrm{C}$ from the 1.368-MeV, ${2}^{+}$ state in $^{24}\mathrm{Mg}$. $\ensuremath{\gamma}$ rays emitted perpendicular to the reaction plane have been measured and $|m|$-substate populations deduced. At $^{13}\mathrm{C}$ scattering angles ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}=10\ifmmode^\circ\else\textdegree\fi{} \mathrm{and} 21\ifmmode^\circ\else\textdegree\fi{}$, probabilities for the $|m|=1$ population (which is equivalent to spin flip) are found to be (1.7\ifmmode\pm\else\textpm\fi{}0.5)% and less than 0.8%, respectively.

Published
1980

12. High-Statistics Measurement of Collins and Sivers Asymmetries for Transversely Polarized Deuterons.

Author

Alexeev GD, Alexeev MG, Alice C, Amoroso A, Andrieux V, Anosov V, Asatryan S, Augsten K, Augustyniak W, Azevedo CDR, Badelek B, Barth J, Beck R, Beckers J, Bedfer Y, Bernhard J, Bodlak M, Bradamante F, Bressan A, Chang WC, Chatterjee C, Chiosso M, Chumakov AG, Chung SU, Cicuttin A, Correia PMM, Crespo ML, D'Ago D, Dalla Torre S, Dasgupta SS, Dasgupta S, Delcarro F, Denisenko I, Denisov OY, Donskov SV, Doshita N, Dreisbach C, Dünnweber W, Dusaev RR, Ecker D, Eremeev D, Faccioli P, Faessler M, Finger M, Finger M, Fischer H, Flöthner KJ, Florian W, Friedrich JM, Frolov V, Garcia Ordòñez LG, Gautheron F, Gavrichtchouk OP, Gerassimov S, Giarra J, Giordano D, Grasso A, Gridin A, Grosse Perdekamp M, Grube B, Grüner M, Guskov A, Haas P, von Harrach D, Hoffmann M, Hoghmrtsyan A, d'Hose N, Hsieh CY, Huber S, Ishimoto S, Ivanov A, Iwata T, Jary V, Joosten R, Kabuß E, Kaspar F, Kerbizi A, Ketzer B, Khatun A, Khaustov GV, Klasek T, Klein F, Koivuniemi JH, Kolosov VN, Kondo Horikawa K, Konorov I, Konstantinov VF, Korzenev AY, Kotzinian AM, Kouznetsov OM, Koval A, Kral Z, Krinner F, Kunne F, Kurek K, Kurjata RP, Kveton A, Lavickova K, Levorato S, Lian YS, Lichtenstadt J, Lin PJ, Longo R, Lyubovitskij VE, Maggiora A, Magnon A, Makke N, Mallot GK, Maltsev A, Martin A, Marzec J, Matoušek J, Matsuda T, Mattson G, Menezes Pires C, Metzger F, Meyer M, Meyer W, Mikhailov YV, Mikhasenko M, Mitrofanov E, Miura D, Miyachi Y, Molina R, Moretti A, Movsisyan A, Nagaytsev A, Neyret D, Niemiec M, Nový J, Nowak WD, Nukazuka G, Olshevsky AG, Ostrick M, Panzieri D, Parsamyan B, Paul S, Pekeler H, Peng JC, Pešek M, Peshekhonov DV, Pešková M, Platchkov S, Pochodzalla J, Polyakov VA, Quaresma M, Quintans C, Reicherz G, Riedl C, Ryabchikov DI, Rychter A, Rymbekova A, Samoylenko VD, Sandacz A, Sarkar S, Savin IA, Sbrizzai G, Schmieden H, Selyunin A, Sharko K, Sinha L, Spülbeck D, Srnka A, Stolarski M, Sulc M, Suzuki H, Takanashi Y, Tessaro S, Tessarotto F, Thiel A, Tosello F, Townsend A, Triloki T, Tskhay V, Valinoti B, Veit BM, Veloso JFCA, Ventura B, Vijayakumar A, Virius M, Wagner M, Wallner S, Zaremba K, Zavertyaev M, Zemko M, Zemlyanichkina E, and Ziembicki M

Abstract

New results are presented on a high-statistics measurement of Collins and Sivers asymmetries of charged hadrons produced in deep inelastic scattering of muons on a transversely polarized ^{6}LiD target. The data were taken in 2022 with the COMPASS spectrometer using the 160 GeV muon beam at CERN, statistically balancing the existing data on transversely polarized proton targets. The first results from about two-thirds of the new data have total uncertainties smaller by up to a factor of three compared to the previous deuteron measurements. Using all the COMPASS proton and deuteron results, both the transversity and the Sivers distribution functions of the u and d quark, as well as the tensor charge in the measured x range are extracted. In particular, the accuracy of the d quark results is significantly improved.

Published
2024
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13. Final COMPASS Results on the Transverse-Spin-Dependent Azimuthal Asymmetries in the Pion-Induced Drell-Yan Process.

Author

Alexeev GD, Alexeev MG, Alice C, Amoroso A, Andrieux V, Anosov V, Augsten K, Augustyniak W, Azevedo CDR, Badelek B, Barth J, Beck R, Beckers J, Bedfer Y, Bernhard J, Bodlak M, Bradamante F, Bressan A, Chang WC, Chatterjee C, Chiosso M, Chumakov AG, Chung SU, Cicuttin A, Correia PMM, Crespo ML, D'Ago D, Dalla Torre S, Dasgupta SS, Dasgupta S, Delcarro F, Denisenko I, Denisov OY, Donskov SV, Doshita N, Dreisbach C, Dünnweber W, Dusaev RR, Ecker D, Eremeev D, Faccioli P, Faessler M, Finger M, Finger M, Fischer H, Flöthner KJ, Florian W, Friedrich JM, Frolov V, Garcia Ordòñez LG, Gautheron F, Gavrichtchouk OP, Gerassimov S, Giarra J, Giordano D, Grasso A, Gridin A, Grosse Perdekamp M, Grube B, Grüner M, Guskov A, Haas P, von Harrach D, Heitz R, Hoffmann M, d'Hose N, Hsieh CY, Huber S, Ishimoto S, Ivanov A, Iwata T, Jary V, Joosten R, Kabuß E, Kaspar F, Kerbizi A, Ketzer B, Khatun A, Khaustov GV, Klein F, Koivuniemi JH, Kolosov VN, Kondo Horikawa K, Konorov I, Konstantinov VF, Korzenev AY, Kotzinian AM, Kouznetsov OM, Koval A, Kral Z, Krinner F, Kunne F, Kurek K, Kurjata RP, Kveton A, Lavickova K, Levorato S, Lian YS, Lichtenstadt J, Lin PJ, Longo R, Lyubovitskij VE, Maggiora A, Magnon A, Makke N, Mallot GK, Maltsev A, Martin A, Marzec J, Matoušek J, Matsuda T, Mattson G, Menezes Pires C, Metzger F, Meyer M, Meyer W, Mikhailov YV, Mikhasenko M, Mitrofanov E, Miura D, Miyachi Y, Molina R, Moretti A, Nagaytsev A, Neyret D, Niemiec M, Nový J, Nowak WD, Nukazuka G, Olshevsky AG, Ostrick M, Panzieri D, Parsamyan B, Paul S, Pekeler H, Peng JC, Pešek M, Peshekhonov DV, Pešková M, Platchkov S, Pochodzalla J, Polyakov VA, Quaresma M, Quintans C, Reicherz G, Riedl C, Ryabchikov DI, Rychter A, Rymbekova A, Samoylenko VD, Sandacz A, Sarkar S, Savada T, Savin IA, Sbrizzai G, Schmieden H, Selyunin A, Sharko K, Sinha L, Spülbeck D, Srnka A, Stolarski M, Sulc M, Suzuki H, Tessaro S, Tessarotto F, Thiel A, Tosello F, Townsend A, Triloki T, Tskhay V, Valinoti B, Veit BM, Veloso JFCA, Ventura B, Vijayakumar A, Virius M, Wagner M, Wallner S, Zaremba K, Zavertyaev M, Zemko M, Zemlyanichkina E, and Ziembicki M

Abstract

The COMPASS Collaboration performed measurements of the Drell-Yan process in 2015 and 2018 using a 190  GeV/c π^{-} beam impinging on a transversely polarized ammonia target. Combining the data of both years, we present final results on the amplitudes of five azimuthal modulations, which correspond to transverse-spin-dependent azimuthal asymmetries (TSAs) in the dimuon production cross section. Three of them probe the nucleon leading-twist Sivers, transversity, and pretzelosity transverse-momentum dependent (TMD) parton distribution functions (PDFs). The other two are induced by subleading effects. These TSAs provide unique new inputs for the study of the nucleon TMD PDFs and their universality properties. In particular, the Sivers TSA observed in this measurement is consistent with the fundamental QCD prediction of a sign change of naive time-reversal-odd TMD PDFs when comparing the Drell-Yan process with deep inelastic scattering. Also, within the context of model predictions, the observed transversity TSA is consistent with the expectation of a sign change for the Boer-Mulders function.

Published
2024
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14. Triangle Singularity as the Origin of the a&#95;{1}(1420).

Author

Alexeev GD, Alexeev MG, Amoroso A, Andrieux V, Anosov V, Antoshkin A, Augsten K, Augustyniak W, Azevedo CDR, Badełek B, Balestra F, Ball M, Barth J, Beck R, Bedfer Y, Berenguer Antequera J, Bernhard J, Bodlak M, Bradamante F, Bressan A, Burtsev VE, Chang WC, Chatterjee C, Chiosso M, Chumakov AG, Chung SU, Cicuttin A, Correia PMM, Crespo ML, D'Ago D, Dalla Torre S, Dasgupta SS, Dasgupta S, Denisenko I, Denisov OY, Donskov SV, Doshita N, Dreisbach C, Dünnweber W, Dusaev RR, Efremov A, Eversheim PD, Faccioli P, Faessler M, Finger M, Finger M, Fischer H, Franco C, Friedrich JM, Frolov V, Gautheron F, Gavrichtchouk OP, Gerassimov S, Giarra J, Gnesi I, Gorzellik M, Grasso A, Gridin A, Grosse Perdekamp M, Grube B, Guskov A, von Harrach D, Heitz R, Herrmann F, Horikawa N, d'Hose N, Hsieh CY, Huber S, Ishimoto S, Ivanov A, Iwata T, Jandek M, Jary V, Joosten R, Jörg P, Kabuß E, Kaspar F, Kerbizi A, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Koivuniemi JH, Kolosov VN, Kondo Horikawa K, Konorov I, Konstantinov VF, Kotzinian AM, Kouznetsov OM, Koval A, Kral Z, Krinner F, Kulinich Y, Kunne F, Kurek K, Kurjata RP, Kveton A, Lavickova K, Levorato S, Lian YS, Lichtenstadt J, Lin PJ, Longo R, Lyubovitskij VE, Maggiora A, Magnon A, Makins N, Makke N, Mallot GK, Maltsev A, Mamon SA, Marianski B, Martin A, Marzec J, Matoušek J, Matsuda T, Mattson G, Meshcheryakov GV, Meyer M, Meyer W, Mikhailov YV, Mikhasenko M, Mitrofanov E, Mitrofanov N, Miyachi Y, Moretti A, Nagaytsev A, Naim C, Neyret D, Nový J, Nowak WD, Nukazuka G, Nunes AS, Olshevsky AG, Ostrick M, Panzieri D, Parsamyan B, Paul S, Pekeler H, Peng JC, Pešek M, Peshekhonov DV, Pešková M, Pierre N, Platchkov S, Pochodzalla J, Polyakov VA, Pretz J, Quaresma M, Quintans C, Reicherz G, Riedl C, Rudnicki T, Ryabchikov DI, Rybnikov A, Rychter A, Samoylenko VD, Sandacz A, Sarkar S, Savin IA, Sbrizzai G, Schmieden H, Selyunin A, Sinha L, Slunecka M, Smolik J, Srnka A, Steffen D, Stolarski M, Subrt O, Sulc M, Suzuki H, Sznajder P, Tessaro S, Tessarotto F, Thiel A, Tomsa J, Tosello F, Townsend A, Tskhay V, Uhl S, Vasilishin BI, Vauth A, Veit BM, Veloso J, Ventura B, Vidon A, Virius M, Wagner M, Wallner S, Zaremba K, Zavada P, Zavertyaev M, Zemko M, Zemlyanichkina E, Zhao Y, and Ziembicki M

Abstract

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a&#95;{1}(1420), decaying to f&#95;{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a&#95;{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a&#95;{1}(1260) resonance into K^{*}(→Kπ)K[over ¯] and subsequent rescattering through a triangle singularity into the coupled f&#95;{0}(980)π channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect.

Published
2021
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15. First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process.

Author

Aghasyan M, Akhunzyanov R, Alexeev GD, Alexeev MG, Amoroso A, Andrieux V, Anfimov NV, Anosov V, Antoshkin A, Augsten K, Augustyniak W, Austregesilo A, Azevedo CDR, Badełek B, Balestra F, Ball M, Barth J, Beck R, Bedfer Y, Bernhard J, Bicker K, Bielert ER, Birsa R, Bodlak M, Bordalo P, Bradamante F, Bressan A, Büchele M, Chang WC, Chatterjee C, Chiosso M, Choi I, Chung SU, Cicuttin A, Crespo ML, Dalla Torre S, Dasgupta SS, Dasgupta S, Denisov OY, Dhara L, Donskov SV, Doshita N, Dreisbach C, Dünnweber W, Dziewiecki M, Efremov A, Eversheim PD, Faessler M, Ferrero A, Finger M, Finger M, Fischer H, Franco C, du Fresne von Hohenesche N, Friedrich JM, Frolov V, Fuchey E, Gautheron F, Gavrichtchouk OP, Gerassimov S, Giarra J, Giordano F, Gnesi I, Gorzellik M, Grasso A, Grosse Perdekamp M, Grube B, Grussenmeyer T, Guskov A, Hahne D, Hamar G, von Harrach D, Heinsius FH, Heitz R, Herrmann F, Horikawa N, d'Hose N, Hsieh CY, Huber S, Ishimoto S, Ivanov A, Ivanshin Y, Iwata T, Jary V, Joosten R, Jörg P, Kabuß E, Kerbizi A, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Koivuniemi JH, Kolosov VN, Kondo K, Königsmann K, Konorov I, Konstantinov VF, Kotzinian AM, Kouznetsov OM, Kral Z, Krämer M, Kremser P, Krinner F, Kroumchtein ZV, Kulinich Y, Kunne F, Kurek K, Kurjata RP, Kveton A, Lednev AA, Levillain M, Levorato S, Lian YS, Lichtenstadt J, Longo R, Maggiora A, Magnon A, Makins N, Makke N, Mallot GK, Marianski B, Martin A, Marzec J, Matoušek J, Matsuda H, Matsuda T, Meshcheryakov GV, Meyer M, Meyer W, Mikhailov YV, Mikhasenko M, Mitrofanov E, Mitrofanov N, Miyachi Y, Nagaytsev A, Nerling F, Neyret D, Nový J, Nowak WD, Nukazuka G, Nunes AS, Olshevsky AG, Orlov I, Ostrick M, Panzieri D, Parsamyan B, Paul S, Peng JC, Pereira F, Pešek M, Peshekhonov DV, Pierre N, Platchkov S, Pochodzalla J, Polyakov VA, Pretz J, Quaresma M, Quintans C, Ramos S, Regali C, Reicherz G, Riedl C, Rogacheva NS, Roskot M, Ryabchikov DI, Rybnikov A, Rychter A, Salac R, Samoylenko VD, Sandacz A, Santos C, Sarkar S, Savin IA, Sawada T, Sbrizzai G, Schiavon P, Schmidt K, Schmieden H, Schönning K, Seder E, Selyunin A, Shevchenko OY, Silva L, Sinha L, Sirtl S, Slunecka M, Smolik J, Srnka A, Steffen D, Stolarski M, Subrt O, Sulc M, Suzuki H, Szabelski A, Szameitat T, Sznajder P, Takewaka S, Tasevsky M, Tessaro S, Terça G, Tessarotto F, Thiel A, Tomsa J, Tosello F, Tskhay V, Uhl S, Vauth A, Veloso J, Virius M, Vit M, Vondra J, Wallner S, Weisrock T, Wilfert M, Ter Wolbeek J, Zaremba K, Zavada P, Zavertyaev M, Zemlyanichkina E, Zhuravlev N, and Ziembicki M

Abstract

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190  GeV/c π^{-} beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3  GeV/c^{2} and 8.5  GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

Published
2017
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16. Observation of a New Narrow Axial-Vector Meson a1(1420).

Author

Adolph C, Akhunzyanov R, Alexeev MG, Alexeev GD, Amoroso A, Andrieux V, Anosov V, Austregesilo A, Azevedo C, Badełek B, Balestra F, Barth J, Beck R, Bedfer Y, Bernhard J, Bicker K, Bielert ER, Birsa R, Bisplinghoff J, Bodlak M, Boer M, Bordalo P, Bradamante F, Braun C, Bressan A, Büchele M, Burtin E, Chang WC, Chiosso M, Choi I, Chung SU, Cicuttin A, Crespo ML, Curiel Q, Dalla Torre S, Dasgupta SS, Dasgupta S, Denisov OY, Dhara L, Donskov SV, Doshita N, Dünnweber W, Duic V, Dziewiecki M, Efremov A, Eversheim PD, Eyrich W, Faessler M, Ferrero A, Finger M, Finger M, Fischer H, Franco C, du Fresne von Hohenesche N, Friedrich JM, Frolov V, Gautheron F, Gavrichtchouk OP, Gerassimov S, Gnesi I, Gorzellik M, Grabmüller S, Grasso A, Grosse-Perdekamp M, Grube B, Grussenmeyer T, Guskov A, Haas F, Hahne D, von Harrach D, Hashimoto R, Heinsius FH, Herrmann F, Hinterberger F, Horikawa N, d'Hose N, Hsieh CY, Huber S, Ishimoto S, Ivanov A, Ivanshin Y, Iwata T, Jahn R, Jary V, Jörg P, Joosten R, Kabuß E, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Klimaszewski K, Koivuniemi JH, Kolosov VN, Kondo K, Königsmann K, Konorov I, Konstantinov VF, Kotzinian AM, Kouznetsov O, Krämer M, Kremser P, Krinner F, Kroumchtein ZV, Kuchinski N, Kunne F, Kurek K, Kurjata RP, Lednev AA, Lehmann A, Levillain M, Levorato S, Lichtenstadt J, Maggiora A, Magnon A, Makins N, Makke N, Mallot GK, Marchand C, Martin A, Marzec J, Matousek J, Matsuda H, Matsuda T, Meshcheryakov G, Meyer W, Michigami T, Mikhailov YV, Miyachi Y, Nagaytsev A, Nagel T, Nerling F, Neyret D, Nikolaenko VI, Novy J, Nowak WD, Nunes AS, Olshevsky AG, Orlov I, Ostrick M, Panzieri D, Parsamyan B, Paul S, Peng JC, Pereira F, Pesek M, Peshekhonov DV, Platchkov S, Pochodzalla J, Polyakov VA, Pretz J, Quaresma M, Quintans C, Ramos S, Regali C, Reicherz G, Riedl C, Rocco E, Rossiyskaya NS, Ryabchikov DI, Rychter A, Samoylenko VD, Sandacz A, Santos C, Sarkar S, Savin IA, Sbrizzai G, Schiavon P, Schmeing S, Schmidt K, Schmieden H, Schönning K, Schopferer S, Schlüter T, Selyunin A, Shevchenko OY, Silva L, Sinha L, Sirtl S, Slunecka M, Sozzi F, Srnka A, Stolarski M, Sulc M, Suzuki H, Szabelski A, Szameitat T, Sznajder P, Takekawa S, Ter Wolbeek J, Tessaro S, Tessarotto F, Thibaud F, Tskhay V, Uhl S, Veloso J, Virius M, Wallner S, Weisrock T, Wilfert M, Zaremba K, Zavertyaev M, Zemlyanichkina E, Ziembicki M, and Zink A

Abstract

The COMPASS Collaboration at CERN has measured diffractive dissociation of 190  GeV/c pions into the π(-)π(-)π(+) final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of 3π mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow peak is observed in the f0(980)π channel with spin, parity and C-parity quantum numbers J(PC)=1(++). We present a resonance-model study of a subset of the spin-density matrix selecting 3π states with J(PC)=2(++) and 4(++) decaying into ρ(770)π and with J(PC)=1(++) decaying into f0(980)π. We identify a new a1 meson with mass (1414(-13)(+15))  MeV/c2 and width (153(-23)(+8))  MeV/c2. Within the final states investigated in our analysis, we observe the new a1(1420) decaying only into f0(980)π, suggesting its exotic nature.

Published
2015
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17. Measurement of the charged-pion polarizability.

Author

Adolph C, Akhunzyanov R, Alexeev MG, Alexeev GD, Amoroso A, Andrieux V, Anosov V, Austregesilo A, Badełek B, Balestra F, Barth J, Baum G, Beck R, Bedfer Y, Berlin A, Bernhard J, Bicker K, Bieling J, Birsa R, Bisplinghoff J, Bodlak M, Boer M, Bordalo P, Bradamante F, Braun C, Bressan A, Büchele M, Burtin E, Capozza L, Chiosso M, Chung SU, Cicuttin A, Colantoni M, Crespo ML, Curiel Q, Dalla Torre S, Dasgupta SS, Dasgupta S, Denisov OY, Dinkelbach AM, Donskov SV, Doshita N, Duic V, Dünnweber W, Dziewiecki M, Efremov A, Elia C, Eversheim PD, Eyrich W, Faessler M, Ferrero A, Filin A, Finger M Jr, Finger M, Fischer H, Franco C, du Fresne von Hohenesche N, Friedrich JM, Frolov V, Gautheron F, Gavrichtchouk OP, Gerassimov S, Geyer R, Gnesi I, Gobbo B, Goertz S, Gorzellik M, Grabmüller S, Grasso A, Grube B, Grussenmeyer T, Guskov A, Guthörl T, Haas F, von Harrach D, Hahne D, Hashimoto R, Heinsius FH, Herrmann F, Hinterberger F, Höppner Ch, Horikawa N, d'Hose N, Huber S, Ishimoto S, Ivanov A, Ivanshin Y, Iwata T, Jahn R, Jary V, Jasinski P, Jörg P, Joosten R, Kabuss E, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Klimaszewski K, Koivuniemi JH, Kolosov VN, Kondo K, Königsmann K, Konorov I, Konstantinov VF, Kotzinian AM, Kouznetsov O, Krämer M, Kroumchtein ZV, Kuchinski N, Kuhn R, Kunne F, Kurek K, Kurjata RP, Lednev AA, Lehmann A, Levillain M, Levorato S, Lichtenstadt J, Maggiora A, Magnon A, Makke N, Mallot GK, Marchand C, Martin A, Marzec J, Matousek J, Matsuda H, Matsuda T, Meshcheryakov G, Meyer W, Michigami T, Mikhailov YV, Miyachi Y, Moinester MA, Nagaytsev A, Nagel T, Nerling F, Neubert S, Neyret D, Nikolaenko VI, Novy J, Nowak WD, Nunes AS, Olshevsky AG, Orlov I, Ostrick M, Panknin R, Panzieri D, Parsamyan B, Paul S, Peshekhonov D, Platchkov S, Pochodzalla J, Polyakov VA, Pretz J, Quaresma M, Quintans C, Ramos S, Regali C, Reicherz G, Rocco E, Rossiyskaya NS, Ryabchikov DI, Rychter A, Samoylenko VD, Sandacz A, Sarkar S, Savin IA, Sbrizzai G, Schiavon P, Schill C, Schlüter T, Schmidt K, Schmieden H, Schönning K, Schopferer S, Schott M, Shevchenko OY, Silva L, Sinha L, Sirtl S, Slunecka M, Sosio S, Sozzi F, Srnka A, Steiger L, Stolarski M, Sulc M, Sulej R, Suzuki H, Szabelski A, Szameitat T, Sznajder P, Takekawa S, ter Wolbeek J, Tessaro S, Tessarotto F, Thibaud F, Uhl S, Uman I, Virius M, Wang L, Weisrock T, Wilfert M, Windmolders R, Wollny H, Zaremba K, Zavertyaev M, Zemlyanichkina E, Ziembicki M, and Zink A

Abstract

The COMPASS collaboration at CERN has investigated pion Compton scattering, π(-)γ→π(-)γ, at center-of-mass energy below 3.5 pion masses. The process is embedded in the reaction π(-)Ni→π(-)γNi, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q(2)<0.0015  (GeV/c)(2). From a sample of 63,000 events, the pion electric polarizability is determined to be α(π)=(2.0±0.6(stat)±0.7(syst))×10(-4)  fm(3) under the assumption α(π)=-β(π), which relates the electric and magnetic dipole polarizabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambiguously known, was performed for an independent estimate of the systematic uncertainty.

Published
2015
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18. First measurement of chiral dynamics in π- γ → π- π- π+.

Author

Adolph C, Alekseev MG, Alexakhin VY, Alexandrov Y, Alexeev GD, Amoroso A, Antonov AA, Austregesilo A, Badełek B, Balestra F, Barth J, Baum G, Bedfer Y, Bernhard J, Bertini R, Bettinelli M, Bicker KA, Birsa R, Bisplinghoff J, Bordalo P, Bradamante F, Braun C, Bravar A, Bressan A, Burtin E, Chaberny D, Chiosso M, Chung SU, Cicuttin A, Crespo ML, Dalla Torre S, Das S, Dasgupta SS, Denisov OY, Dhara L, Donskov SV, Doshita N, Duic V, Dünnweber W, Dziewiecki M, Efremov A, Elia C, Eversheim PD, Eyrich W, Faessler M, Ferrero A, Filin A, Finger M, Finger M Jr, Fischer H, Franco C, du Fresne von Hohenesche N, Friedrich JM, Garfagnini R, Gautheron F, Gavrichtchouk OP, Gazda R, Gerassimov S, Geyer R, Giorgi M, Gnesi I, Gobbo B, Goertz S, Grabmüller S, Grasso A, Grube B, Gushterski R, Guskov A, Haas F, von Harrach D, Hasegawa T, Heinsius FH, Herrmann F, Hess C, Hinterberger F, Horikawa N, Höppner Ch, d'Hose N, Huber S, Ishimoto S, Ivanov O, Ivanshin Y, Iwata T, Jahn R, Jasinski P, Jegou G, Joosten R, Kabuss E, Kang D, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Klimaszewski K, Koblitz S, Koivuniemi JH, Kolosov VN, Kondo K, Königsmann K, Konorov I, Konstantinov VF, Korzenev A, Kotzinian AM, Kouznetsov O, Krämer M, Kroumchtein ZV, Kunne F, Kurek K, Lauser L, Lednev AA, Lehmann A, Levorato S, Lichtenstadt J, Maggiora A, Magnon A, Makke N, Mallot GK, Mann A, Marchand C, Martin A, Marzec J, Massmann F, Matsuda T, Meyer W, Michigami T, Mikhailov YV, Moinester MA, Morreale A, Mutter A, Nagaytsev A, Nagel T, Nerling F, Neubert S, Neyret D, Nikolaenko VI, Nowak WD, Nunes AS, Olshevsky AG, Ostrick M, Padee A, Panknin R, Panzieri D, Parsamyan B, Paul S, Perevalova E, Pesaro G, Peshekhonov DV, Piragino G, Platchkov S, Pochodzalla J, Polak J, Polyakov VA, Pontecorvo G, Pretz J, Quintans C, Rajotte JF, Ramos S, Rapatsky V, Reicherz G, Richter A, Rocco E, Rondio E, Rossiyskaya NS, Ryabchikov DI, Samoylenko VD, Sandacz A, Sapozhnikov MG, Sarkar S, Savin IA, Sbrizzai G, Schiavon P, Schill C, Schlüter T, Schmitt L, Schönning K, Schopferer S, Schröder W, Shevchenko OY, Siebert HW, Silva L, Sinha L, Sissakian AN, Slunecka M, Smirnov GI, Sosio S, Sozzi F, Srnka A, Stolarski M, Sulc M, Sulej R, Sznajder P, Takekawa S, Ter Wolbeek J, Tessaro S, Tessarotto F, Teufel A, Tkatchev LG, Uhl S, Uman I, Vandenbroucke M, Virius M, Vlassov NV, Windmolders R, Wiślicki W, Wollny H, Zaremba K, Zavertyaev M, Zemlyanichkina E, Ziembicki M, Zhuravlev N, and Zvyagin A

Abstract

The COMPASS Collaboration at CERN has investigated the π- γ → π- π- π+ reaction at center-of-momentum energy below five pion masses, sqrt[s]<5m(π), embedded in the Primakoff reaction of 190 GeV pions impinging on a lead target. Exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, t'<0.001  GeV2/c2. Using partial-wave analysis techniques, the scattering intensity of Coulomb production described in terms of chiral dynamics and its dependence on the 3π-invariant mass m(3π)=sqrt[s] were extracted. The absolute cross section was determined in seven bins of sqrt[s] with an overall precision of 20%. At leading order, the result is found to be in good agreement with the prediction of chiral perturbation theory over the whole energy range investigated.

Published
2012
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19. Observation of a J(PC)=1-+ exotic resonance in diffractive dissociation of 190   GeV/c π- into π- π- π+.

Author

Alekseev MG, Alexakhin VY, Alexandrov Y, Alexeev GD, Amoroso A, Austregesilo A, Badełek B, Balestra F, Ball J, Barth J, Baum G, Bedfer Y, Bernhard J, Bertini R, Bettinelli M, Birsa R, Bisplinghoff J, Bordalo P, Bradamante F, Bravar A, Bressan A, Brona G, Burtin E, Bussa MP, Chapiro A, Chiosso M, Chung SU, Cicuttin A, Colantoni M, Crespo ML, Dalla Torre S, Dafni T, Das S, Dasgupta SS, Denisov OY, Dhara L, Diaz V, Dinkelbach AM, Donskov SV, Doshita N, Duic V, Dünnweber W, Efremov A, El Alaoui A, Eversheim PD, Eyrich W, Faessler M, Ferrero A, Finger M, Finger M Jr, Fischer H, Franco C, Friedrich JM, Garfagnini R, Gautheron F, Gavrichtchouk OP, Gazda R, Gerassimov S, Geyer R, Giorgi M, Gobbo B, Goertz S, Grabmüller S, Grajek OA, Grasso A, Grube B, Gushterski R, Guskov A, Haas F, von Harrach D, Hasegawa T, Heckmann J, Heinsius FH, Hermann R, Herrmann F, Hess C, Hinterberger F, Horikawa N, Höppner Ch, d'Hose N, Ilgner C, Ishimoto S, Ivanov O, Ivanshin Y, Iwata T, Jahn R, Jasinski P, Jegou G, Joosten R, Kabuss E, Kang D, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Klimaszewski K, Koblitz S, Koivuniemi JH, Kolosov VN, Komissarov EV, Kondo K, Königsmann K, Konopka R, Konorov I, Konstantinov VF, Korzenev A, Kotzinian AM, Kouznetsov O, Kowalik K, Krämer M, Kral A, Kroumchtein ZV, Kuhn R, Kunne F, Kurek K, Lauser L, Le Goff JM, Lednev AA, Lehmann A, Levorato S, Lichtenstadt J, Liska T, Maggiora A, Maggiora M, Magnon A, Mallot GK, Mann A, Marchand C, Marroncle J, Martin A, Marzec J, Massmann F, Matsuda T, Maximov AN, Meyer W, Michigami T, Mikhailov YV, Moinester MA, Mutter A, Nagaytsev A, Nagel T, Nassalski J, Negrini T, Nerling F, Neubert S, Neyret D, Nikolaenko VI, Olshevsky AG, Ostrick M, Padee A, Panknin R, Panzieri D, Parsamyan B, Paul S, Pawlukiewicz-Kaminska B, Perevalova E, Pesaro G, Peshekhonov DV, Piragino G, Platchkov S, Pochodzalla J, Polak J, Polyakov VA, Pontecorvo G, Pretz J, Quintans C, Rajotte JF, Ramos S, Rapatsky V, Reicherz G, Reggiani D, Richter A, Robinet F, Rocco E, Rondio E, Ryabchikov DI, Samoylenko VD, Sandacz A, Santos H, Sapozhnikov MG, Sarkar S, Savin IA, Sbrizzai G, Schiavon P, Schill C, Schlüter T, Schmitt L, Schopferer S, Schröder W, Shevchenko OY, Siebert HW, Silva L, Sinha L, Sissakian AN, Slunecka M, Smirnov GI, Sosio S, Sozzi F, Srnka A, Stolarski M, Sulc M, Sulej R, Takekawa S, Tessaro S, Tessarotto F, Teufel A, Tkatchev LG, Uhl S, Uman I, Venugopal G, Virius M, Vlassov NV, Vossen A, Weitzel Q, Windmolders R, Wiślicki W, Wollny H, Zaremba K, Zavertyaev M, Zemlyanichkina E, Ziembicki M, Zhao J, Zhuravlev N, and Zvyagin A

Abstract

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66  GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0))  MeV/c2 and a width of (269±21(-64)(+42))  MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.

Published
2010
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20. First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering.

Author

Alexakhin VY, Alexandrov Y, Alexeev GD, Amoroso A, Badełek B, Balestra F, Ball J, Baum G, Bedfer Y, Berglund P, Bernet C, Bertini R, Birsa R, Bisplinghoff J, Bradamante F, Bravar A, Bressan A, Burtin E, Bussa MP, Cerini L, Chapiro A, Cicuttin A, Colantoni M, Colavita AA, Costa S, Crespo ML, d'Hose N, Dalla Torre S, Dasgupta SS, De Masi R, Dedek N, Denisov OY, Dhara L, Diaz Kavka V, Dolgopolov AV, Donskov SV, Dorofeev VA, Doshita N, Duic V, Dünnweber W, Efremov A, Ehlers J, Eversheim PD, Eyrich W, Fabro M, Faessler M, Fauland P, Ferrero A, Ferrero L, Finger M, Finger M Jr, Fischer H, Franz J, Friedrich JM, Frolov V, Fuchs U, Garfagnini R, Gautheron F, Gavrichtchouk OP, Gerassimov S, Geyer R, Giorgi M, Gobbo B, Goertz S, Grajek OA, Grasso A, Grube B, Grünemaier A, Gustafsson K, Hannappel J, von Harrach D, Hasegawa T, Hedicke S, Heinsius FH, Hinterberger F, von Hodenberg M, Horikawa N, Horikawa S, Ijaduola RB, Ilgner C, Ishimoto S, Iwata T, Jahn R, Janata A, Joosten R, Jouravlev NI, Kabuss E, Kalinnikov V, Kang D, Karstens F, Kastaun W, Ketzer B, Khaustov GV, Khokhlov YA, Kisselev Y, Klein F, Koivuniemi JH, Kolosov VN, Komissarov EV, Kondo K, Königsmann K, Konoplyannikov AK, Konorov I, Konstantinov VF, Korentchenko AS, Korzenev A, Kotzinian AM, Koutchinski NA, Kowalik K, Kravchuk NP, Krivokhizhin GV, Kroumchtein ZV, Kuhn R, Kunne F, Kurek K, Lamanna M, Le Goff JM, Leberig M, Lichtenstadt J, Maggiora A, Maggiora M, Magnon A, Mallot GK, Manuilov IV, Marchand C, Marroncle J, Martin A, Marzec J, Matsuda T, Maximov AN, Medved KS, Meyer W, Mielech A, Mikhailov YV, Moinester MA, Nähle O, Nassalski J, Neyret DP, Nikolaenko VI, Nozdrin AA, Obraztsov VF, Olshevsky AG, Ostrick M, Padee A, Pagano P, Panebianco S, Panzieri D, Paul S, Pereira HD, Peshekhonov DV, Peshekhonov VD, Piragino G, Platchkov S, Platzer K, Pochodzalla J, Polyakov VA, Popov AA, Pretz J, Rebourgeard PC, Reicherz G, Reymann J, Rozhdestvensky AM, Rondio E, Sadovski AB, Saller E, Samoylenko VD, Sandacz A, Sans M, Sapozhnikov MG, Savin IA, Schiavon P, Schmidt T, Schmitt H, Schmitt L, Shishkin AA, Siebert H, Sinha L, Sissakian AN, Skachkova A, Slunecka M, Smirnov GI, Sugonyaev VP, Stinzing F, Sulej R, Takabayashi N, Tchalishev VV, Tessarotto F, Teufel A, Thers D, Tkatchev LG, Toeda T, Tretyak VI, Trousov S, Vlassov NV, Webb R, Weise E, Wiesmann M, Windmolders R, Wirth S, Wiślicki W, Zanetti AM, Zaremba K, Zhao J, Ziegler R, and Zvyagin A

Abstract

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

Published
2005
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