Abstract
As first observed by the NA48/2 experiment at the CERN SPS, the π0π0 invariant mass (M00) distribution from K±→π±π0π0 decay shows a cusp-like anomaly at M00=2m+, where m+ is the charged pion mass. An analysis to extract the ππ scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively, has been recently reported. In the present work the Dalitz plot of this decay is fitted to a new empirical parameterization suitable for practical purposes, such as Monte Carlo simulations of K±→π±π0π0 decays.
Highlights
Since 1960 the square of the matrix element absolute value |M | which describes the K± → π±π0π0 Dalitz plot distribution has been parameterized by a series expansion such as that introduced by Weinberg [1]: d|M |2 dU dV ∝ 1 + GU + HU2 + KV 2 + ..., (1)where U = (s3 − s0)/m2π+, V = (s2 − s1)/m2π+ and si = (PK − Pi)2, i = 1, 2, 3; s0 = (m2K+ + 2m2π0 + m2π+ )/3.Here Pi are the ith pion four-momenta and i = 3 is assigned to the charged pion
In 2005 the NA48/2 experiment at the CERN SPS first observed a cusp-like anomaly in the π0π0 invariant mass (M00) distribution of this decay in the region around M00 = 2m+, where m+ is the charged pion mass [5]
In order to describe the cusp observed in the π0π0 invariant mass distribution, we propose the following empirical parameterization for the square of the K± → π±π0π0 decay matrix element: d|M |2 dU dV
Summary
J.R. Batley1, A.J. Culling1, G. Kalmus1, C. Lazzeroni1,22, D.J. Munday1, M.W. Slater1,22, S.A. Wotton1, R. Arcidiacono2,19,20, G. Bocquet2, N. Cabibbo2,23,24, A. Ceccucci2, D. Cundy2,25, V. Falaleev2, M. Fidecaro2, L. Gatignon2, A. Gonidec2, W. Kubischta2, A. Norton2,6,7, A. Maier2, M. Patel2, A. Peters2, S. Balev3,14,15, P.L. Frabetti3, E. Goudzovski3,22, P. Hristov3,2, V. Kekelidze3, V. Kozhuharov3,26, L. Litov3, D. Madigozhin3, E. Marinova3,13, N. Molokanova3, I. Polenkevich3, Yu. Potrebenikov3, S. Stoynev3,11, A. Zinchenko3, E. Monnier4,27, E. Swallow4, R. Winston4, P. Rubin5,28, A. Walker5, W. Baldini6,7, A. Cotta Ramusino6,7, P. Dalpiaz6,7, C. Damiani6,7, M. Fiorini6,7,2, A. Gianoli6,7, M. Martini6,7, F. Petrucci6,7, M. Savrie6,7, M. Scarpa6,7, H. Wahl6,7, M. Calvetti8,9, E. Iacopini8,9, G. Ruggiero8,9,14,15, A. Bizzeti9,29, M. Lenti9, M. Veltri9,30, M. Behler10, K. Eppard10, K. Kleinknecht10, P. Marouelli10, L. Masetti10,31, U. Moosbrugger10, C. Morales Morales10, B. Renk10, M. Wache10, R. Wanke10, A. Winhart10, D. Coward11,32, A. Dabrowski11, T. Fonseca Martin11,33, M. Shieh11, M. Szleper11, M. Velasco11, M.D. Wood11,34, G. Anzivino12,13, E. Imbergamo12,13, A. Nappi12,13, M. Piccini12,13, M. Raggi12,13,35, M. Valdata-Nappi12,13, P. Cenci13, M. Pepe13, M.C. Petrucci13, C. Cerri14, R. Fantechi14, G. Collazuol14,15, L. DiLella14,15, G. Lamanna14,15, I. Mannelli14,15, A. Michetti14,15, F. Costantini14,16, N. Doble16, L. Fiorini14,16,36, S. Giudici14,16, G. Pierazzini14,16, M. Sozzi14,16, S. Venditti14,16, B. Bloch-Devaux17, C. Cheshkov17,2, J.B. Cheze17, M. De Beer17, J. Derre17, G. Marel17, E. Mazzucato17, B. Peyaud17, B. Vallage17, M. Holder18, M. Ziolkowski18, C. Biino19, N. Cartiglia19, F. Marchetto19, S. Bifani19,20,37, M. Clemencic19,20,2, S. Goy Lopez19,20,38, H. Dibon21, M. Jeitler21, M. Markytan21, I. Mikulec21, G. Neuhofer21, L. Widhalm21 Road, Edinburgh, EH9 3JZ, UK 6Dipartimento di Fisica dell’Universita, I-44100 Ferrara, Italy 11Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA 12Dipartimento di Fisica dell’Universita, I-06100 Perugia, Italy 13Sezione dell’INFN di Perugia, I-06100 Perugia, Italy 14Sezione dell’INFN di Pisa, I-56100 Pisa, Italy 15Scuola Normale Superiore, I-56100 Pisa, Italy 16Dipartimento di Fisica dell’Universita, I-56100 Pisa, Italy 17DSM/IRFU - CEA Saclay, F-91191 Gif-sur-Yvette, France 18Fachbereich Physik, Universitat Siegen, D-57068 Siegen, Germany41 19Sezione dell’INFN di Torino, I-10125 Torino, Italy 20Dipartimento di Fisica Sperimentale dell’Universita, I-10125 Torino, Italy 21Osterreichische Akademie der Wissenschaften, Institut fur Hochenergiephysik, A-10560 Wien, Austria42 22University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK 23Universitadi Roma “La Sapienza”, I-00185 Roma, Italy 24Sezione dell’INFN di Roma, I-00185 Roma, Italy 25Istituto di Cosmogeofisica del CNR di Torino, I-10133 Torino, Italy 26Faculty of Physics, University of Sofia “St. Kl. Ohridski”, 5 J. Bourchier Blvd., 1164 Sofia, Bulgaria 27Centre de Physique des Particules de Marseille, IN2P3-CNRS, Universite de la Mediterranee, Marseille, France 28Department of Physics and Astronomy, George Mason University, Fairfax, VA 22030, USA 29Dipartimento di Fisica, Universitadi Modena e Reggio Emilia, I-41100 Modena, Italy 30Istituto di Fisica, Universitadi Urbino, I-61029 Urbino, Italy 31Physikalisches Institut, Universitat Bonn, D-53115 Bonn, Germany 32SLAC, Stanford University, Menlo Park, CA 94025, USA 33Royal Holloway, University of London, Egham Hill, Egham, TW20 0EX, UK 34UCLA, Los Angeles, CA 90024, USA 35Laboratori Nazionali di Frascati, I-00044 Frascati (Rome), Italy 36Institut de Fısica d’Altes Energies, UAB, E-08193 Bellaterra (Barcelona), Spain 37University of Bern, Institute for Theoretical Physics, Sidlerstrasse 5, CH-3012 Bern, Switzerland 38Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, E-28040 Madrid, Spain
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