Measurement of the charged-pion polarizability
Affiliations
- 1 Universität Erlangen-Nürnberg, Physikalisches Institut, 91054 Erlangen, Germany.
- 2 Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia.
- 3 University of Turin, Department of Physics, 10125 Turin, Italy.
- 4 University of Turin, Department of Physics, 10125 Turin, Italy and Torino Section of INFN, 10125 Turin, Italy.
- 5 CEA IRFU/SPhN Saclay, 91191 Gif-sur-Yvette, France.
- 6 CERN, 1211 Geneva 23, Switzerland and Technische Universität München, Physik Department, 85748 Garching, Germany.
- 7 University of Warsaw, Faculty of Physics, 00-681 Warsaw, Poland.
- 8 Universität Bonn, Physikalisches Institut, 53115 Bonn, Germany.
- 9 Universität Bielefeld, Fakultät für Physik, 33501 Bielefeld, Germany.
- 10 Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, 53115 Bonn, Germany.
- 11 Universität Bochum, Institut für Experimentalphysik, 44780 Bochum, Germany.
- 12 Universität Mainz, Institut für Kernphysik, 55099 Mainz, Germany.
- 13 Trieste Section of INFN, 34127 Trieste, Italy.
- 14 Charles University in Prague, Faculty of Mathematics and Physics, 18000 Prague, Czech Republic.
- 15 LIP, 1000-149 Lisbon, Portugal.
- 16 University of Trieste, Department of Physics, 34127 Trieste, Italy and Trieste Section of INFN, 34127 Trieste, Italy.
- 17 Universität Freiburg, Physikalisches Institut, 79104 Freiburg, Germany.
- 18 Technische Universität München, Physik Department, 85748 Garching, Germany.
- 19 Trieste Section of INFN, 34127 Trieste, Italy and Abdus Salam ICTP, 34151 Trieste, Italy.
- 20 Torino Section of INFN, 10125 Turin, Italy.
- 21 Matrivani Institute of Experimental Research & Education, Calcutta 700 030, India.
- 22 State Scientific Center Institute for High Energy Physics of National Research Center "Kurchatov Institute," 142281 Protvino, Russia.
- 23 Yamagata University, Yamagata, 992-8510 Japan.
- 24 University of Trieste, Department of Physics, 34127 Trieste, Italy.
- 25 Ludwig-Maximilians-Universität München, Department für Physik, 80799 Munich, Germany.
- 26 Warsaw University of Technology, Institute of Radioelectronics, 00-665 Warsaw, Poland.
- 27 CERN, 1211 Geneva 23, Switzerland and Universität Mainz, Institut für Kernphysik, 55099 Mainz, Germany.
- 28 CERN, 1211 Geneva 23, Switzerland.
- 29 Lebedev Physical Institute, 119991 Moscow, Russia and Technische Universität München, Physik Department, 85748 Garching, Germany.
- 30 Nagoya University, 464 Nagoya, Japan.
- 31 Czech Technical University in Prague, 16636 Prague, Czech Republic.
- 32 National Centre for Nuclear Research, 00-681 Warsaw, Poland.
- 33 Tel Aviv University, School of Physics and Astronomy, 69978 Tel Aviv, Israel.
- 34 University of Miyazaki, Miyazaki 889-2192, Japan.
- 35 University of Eastern Piedmont, 15100 Alessandria, Italy and Torino Section of INFN, 10125 Turin, Italy.
- 36 Institute of Scientific Instruments, AS CR, 61264 Brno, Czech Republic.
- 37 Technical University in Liberec, 46117 Liberec, Czech Republic.
- 38 Lebedev Physical Institute, 119991 Moscow, Russia.
- PMID: 25723208
- DOI: 10.1103/PhysRevLett.114.062002
Measurement of the charged-pion polarizability
Authors
Affiliations
- 1 Universität Erlangen-Nürnberg, Physikalisches Institut, 91054 Erlangen, Germany.
- 2 Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region, Russia.
- 3 University of Turin, Department of Physics, 10125 Turin, Italy.
- 4 University of Turin, Department of Physics, 10125 Turin, Italy and Torino Section of INFN, 10125 Turin, Italy.
- 5 CEA IRFU/SPhN Saclay, 91191 Gif-sur-Yvette, France.
- 6 CERN, 1211 Geneva 23, Switzerland and Technische Universität München, Physik Department, 85748 Garching, Germany.
- 7 University of Warsaw, Faculty of Physics, 00-681 Warsaw, Poland.
- 8 Universität Bonn, Physikalisches Institut, 53115 Bonn, Germany.
- 9 Universität Bielefeld, Fakultät für Physik, 33501 Bielefeld, Germany.
- 10 Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, 53115 Bonn, Germany.
- 11 Universität Bochum, Institut für Experimentalphysik, 44780 Bochum, Germany.
- 12 Universität Mainz, Institut für Kernphysik, 55099 Mainz, Germany.
- 13 Trieste Section of INFN, 34127 Trieste, Italy.
- 14 Charles University in Prague, Faculty of Mathematics and Physics, 18000 Prague, Czech Republic.
- 15 LIP, 1000-149 Lisbon, Portugal.
- 16 University of Trieste, Department of Physics, 34127 Trieste, Italy and Trieste Section of INFN, 34127 Trieste, Italy.
- 17 Universität Freiburg, Physikalisches Institut, 79104 Freiburg, Germany.
- 18 Technische Universität München, Physik Department, 85748 Garching, Germany.
- 19 Trieste Section of INFN, 34127 Trieste, Italy and Abdus Salam ICTP, 34151 Trieste, Italy.
- 20 Torino Section of INFN, 10125 Turin, Italy.
- 21 Matrivani Institute of Experimental Research & Education, Calcutta 700 030, India.
- 22 State Scientific Center Institute for High Energy Physics of National Research Center "Kurchatov Institute," 142281 Protvino, Russia.
- 23 Yamagata University, Yamagata, 992-8510 Japan.
- 24 University of Trieste, Department of Physics, 34127 Trieste, Italy.
- 25 Ludwig-Maximilians-Universität München, Department für Physik, 80799 Munich, Germany.
- 26 Warsaw University of Technology, Institute of Radioelectronics, 00-665 Warsaw, Poland.
- 27 CERN, 1211 Geneva 23, Switzerland and Universität Mainz, Institut für Kernphysik, 55099 Mainz, Germany.
- 28 CERN, 1211 Geneva 23, Switzerland.
- 29 Lebedev Physical Institute, 119991 Moscow, Russia and Technische Universität München, Physik Department, 85748 Garching, Germany.
- 30 Nagoya University, 464 Nagoya, Japan.
- 31 Czech Technical University in Prague, 16636 Prague, Czech Republic.
- 32 National Centre for Nuclear Research, 00-681 Warsaw, Poland.
- 33 Tel Aviv University, School of Physics and Astronomy, 69978 Tel Aviv, Israel.
- 34 University of Miyazaki, Miyazaki 889-2192, Japan.
- 35 University of Eastern Piedmont, 15100 Alessandria, Italy and Torino Section of INFN, 10125 Turin, Italy.
- 36 Institute of Scientific Instruments, AS CR, 61264 Brno, Czech Republic.
- 37 Technical University in Liberec, 46117 Liberec, Czech Republic.
- 38 Lebedev Physical Institute, 119991 Moscow, Russia.
- PMID: 25723208
- DOI: 10.1103/PhysRevLett.114.062002
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.
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