Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays

J. Abdallah; P. Abreu; W. Adam; P. Adzic; T. Albrecht; R. Alemany-Fernandez; T. Allmendinger; P. P. Allport; U. Amaldi; N. Amapane; S. Amato; E. Anashkin; A. Andreazza; S. Andringa; N. Anjos; P. Antilogus; W-D. Apel; Y. Arnoud; S. Ask; B. Asman; J. E. Augustin; A. Augustinus; P. Baillon; A. Ballestrero; P. Bambade; R. Barbier; D. Bardin; G. J. Barker; A. Baroncelli; M. Battaglia; M. Baubillier; K-H. Becks; M. Begalli; A. Behrmann; E. Ben-Haim; N. Benekos; A. Benvenuti; C. Berat; M. Berggren; D. Bertrand; M. Besancon; N. Besson; D. Bloch; M. Blom; M. Bluj; M. Bonesini; M. Boonekamp; P. S. L. Booth; G. Borisov; O. Botner; B. Bouquet; T. J. V. Bowcock; I. Boyko; M. Bracko; R. Brenner; E. Brodet; P. Bruckman; J. M. Brunet; B. Buschbeck; P. Buschmann; M. Calvi; T. Camporesi; V. Canale; F. Carena; N. Castro; F. Cavallo; M. Chapkin; Ph. Charpentier; P. Checchia; R. Chierici; P. Chliapnikov; J. Chudoba; S. U. Chung; K. Cieslik; P. Collins; R. Contri; G. Cosme; F. Cossutti; M. J. Costa; D. Crennell; J. Cuevas; J. D’Hondt; T. da Silva; W. Da Silva; G. Della Ricca; A. De Angelis; W. De Boer; C. De Clercq; B. De Lotto; N. De Maria; A. De Min; L. de Paula; L. Di Ciaccio; A. Di Simone; K. Doroba; J. Drees; G. Eigen; T. Ekelof; M. Ellert; M. Elsing; M. C. Espirito Santo; G. Fanourakis; D. Fassouliotis; M. Feindt; J. Fernandez; A. Ferrer; F. Ferro; U. Flagmeyer; H. Foeth; E. Fokitis; F. Fulda-Quenzer; J. Fuster; M. Gandelman; C. Garcia; Ph. Gavillet; E. Gazis; R. Gokieli; B. Golob; G. Gomez-Ceballos; P. Goncalves; E. Graziani; G. Grosdidier; K. Grzelak; J. Guy; C. Haag; A. Hallgren; K. Hamacher; K. Hamilton; S. Haug; F. Hauler; V. Hedberg; M. Hennecke; J. Hoffman; S-O. Holmgren; P. J. Holt; M. A. Houlden; J. N. Jackson; G. Jarlskog; P. Jarry; D. Jeans; E. K. Johansson; P. Jonsson; C. Joram; L. Jungermann; F. Kapusta; S. Katsanevas; E. Katsoufis; G. Kernel; B. P. Kersevan; U. Kerzel; B. T. King; N. J. Kjaer; P. Kluit; P. Kokkinias; C. Kourkoumelis; O. Kouznetsov; Z. Krumstein; M. Kucharczyk; J. Lamsa; G. Leder; F. Ledroit; L. Leinonen; R. Leitner; J. Lemonne; V. Lepeltier; T. Lesiak; W. Liebig; D. Liko; A. Lipniacka; J. H. Lopes; J. M. Lopez; D. Loukas; P. Lutz; L. Lyons; J. MacNaughton; A. Malek; S. Maltezos; F. Mandl; J. Marco; R. Marco; B. Marechal; M. Margoni; J-C. Marin; C. Mariotti; A. Markou; C. Martinez-Rivero; J. Masik; N. Mastroyiannopoulos; F. Matorras; C. Matteuzzi; F. Mazzucato; M. Mazzucato; R. Mc Nulty; C. Meroni; E. Migliore; W. Mitaroff; U. Mjoernmark; T. Moa; M. Moch; K. Moenig; R. Monge; J. Montenegro; D. Moraes; S. Moreno; P. Morettini; U. Mueller; K. Muenich; M. Mulders; L. Mundim; W. Murray; B. Muryn; G. Myatt; T. Myklebust; M. Nassiakou; F. Navarria; K. Nawrocki; S. Nemecek; R. Nicolaidou; M. Nikolenko; A. Oblakowska-Mucha; V. Obraztsov; A. Olshevski; A. Onofre; R. Orava; K. Osterberg; A. Ouraou; A. Oyanguren; M. Paganoni; S. Paiano; J. P. Palacios; H. Palka; Th. D. Papadopoulou; L. Pape; C. Parkes; F. Parodi; U. Parzefall; A. Passeri; O. Passon; L. Peralta; V. Perepelitsa; A. Perrotta; A. Petrolini; J. Piedra; L. Pieri; F. Pierre; M. Pimenta; E. Piotto; T. Podobnik; V. Poireau; M. E. Pol; G. Polok; V. Pozdniakov; N. Pukhaeva; A. Pullia; D. Radojicic; P. Rebecchi; J. Rehn; D. Reid; R. Reinhardt; P. Renton; F. Richard; J. Ridky; M. Rivero; D. Rodriguez; A. Romero; P. Ronchese; P. Roudeau; T. Rovelli; V. Ruhlmann-Kleider; D. Ryabtchikov; A. Sadovsky; L. Salmi; J. Salt; C. Sander; A. Savoy-Navarro; U. Schwickerath; R. Sekulin; M. Siebel; A. Sisakian; G. Smadja; O. Smirnova; A. Sokolov; A. Sopczak; R. Sosnowski; T. Spassov; M. Stanitzki; A. Stocchi; J. Strauss; B. Stugu; M. Szczekowski; M. Szeptycka; T. Szumlak; T. Tabarelli; F. Tegenfeldt; J. Timmermans; L. Tkatchev; M. Tobin; S. Todorovova; B. Tome; A. Tonazzo; P. Tortosa; P. Travnicek; D. Treille; G. Tristram; M. Trochimczuk; C. Troncon; M-L. Turluer; I. A. Tyapkin; P. Tyapkin; S. Tzamarias; V. Uvarov; G. Valenti; P. Van Dam; J. Van Eldik; N. van Remortel; I. Van Vulpen; G. Vegni; F. Veloso; W. Venus; P. Verdier; V. Verzi; D. Vilanova; L. Vitale; V. Vrba; H. Wahlen; A. J. Washbrook; C. Weiser; D. Wicke; J. Wickens; G. Wilkinson; M. Winter; M. Witek; O. Yushchenko; A. Zalewska; P. Zalewski; D. Zavrtanik; V. Zhuravlov; N. I. Zimin; A. Zintchenko; M. Zupan

doi:10.1140/epjc/s10052-010-1315-5

2021 Impact factor 4.991

Particles and Fields

Open Access

Eur. Phys. J. C (2010) 67: 343-366
https://doi.org/10.1140/epjc/s10052-010-1315-5

Regular Article - Experimental Physics

Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z ⁰ decays

The DELPHI Collaboration
J. Abdallah²⁷, P. Abreu²⁴, W. Adam⁵⁷, P. Adzic¹³, T. Albrecht¹⁹, R. Alemany-Fernandez¹⁰, T. Allmendinger¹⁹, P. P. Allport²⁵, U. Amaldi³¹, N. Amapane⁴⁹, S. Amato⁵³, E. Anashkin³⁸, A. Andreazza³⁰, S. Andringa²⁴, N. Anjos²⁴, P. Antilogus²⁷, W-D. Apel¹⁹, Y. Arnoud¹⁶, S. Ask¹⁰, B. Asman⁴⁸, J. E. Augustin²⁷, A. Augustinus¹⁰, P. Baillon¹⁰, A. Ballestrero⁵⁰, P. Bambade²², R. Barbier²⁹, D. Bardin¹⁸, G. J. Barker, A. Baroncelli⁴¹, M. Battaglia¹⁰, M. Baubillier²⁷, K-H. Becks⁶⁰, M. Begalli⁸, A. Behrmann⁶⁰, E. Ben-Haim²⁷, N. Benekos³⁴, A. Benvenuti⁶, C. Berat¹⁶, M. Berggren²⁷, D. Bertrand³, M. Besancon⁴², N. Besson⁴², D. Bloch¹¹, M. Blom³³, M. Bluj⁵⁸, M. Bonesini³¹, M. Boonekamp⁴², P. S. L. Booth²⁵, G. Borisov²³, O. Botner⁵⁴, B. Bouquet²², T. J. V. Bowcock²⁵, I. Boyko¹⁸, M. Bracko⁴⁵, R. Brenner⁵⁴, E. Brodet³⁷, P. Bruckman²⁰, J. M. Brunet⁹, B. Buschbeck⁵⁷, P. Buschmann⁶⁰, M. Calvi³¹, T. Camporesi¹⁰, V. Canale⁴⁰, F. Carena¹⁰, N. Castro²⁴, F. Cavallo⁶, M. Chapkin⁴⁴, Ph. Charpentier¹⁰, P. Checchia³⁸, R. Chierici¹⁰, P. Chliapnikov⁴⁴, J. Chudoba¹⁰, S. U. Chung¹⁰, K. Cieslik²⁰, P. Collins¹⁰, R. Contri¹⁵, G. Cosme²², F. Cossutti⁵¹, M. J. Costa⁵⁵, D. Crennell³⁹, J. Cuevas³⁶, J. D’Hondt³, T. da Silva⁵³, W. Da Silva²⁷, G. Della Ricca⁵¹, A. De Angelis⁵², W. De Boer¹⁹, C. De Clercq³, B. De Lotto⁵², N. De Maria⁴⁹, A. De Min³⁸, L. de Paula⁵³, L. Di Ciaccio⁴⁰, A. Di Simone⁴¹, K. Doroba⁵⁸, J. Drees¹⁰^,60, G. Eigen⁵, T. Ekelof⁵⁴, M. Ellert⁵⁴, M. Elsing¹⁰, M. C. Espirito Santo²⁴, G. Fanourakis¹³, D. Fassouliotis⁴^,13, M. Feindt¹⁹, J. Fernandez⁴³, A. Ferrer⁵⁵, F. Ferro¹⁵, U. Flagmeyer⁶⁰, H. Foeth¹⁰, E. Fokitis³⁴, F. Fulda-Quenzer²², J. Fuster⁵⁵, M. Gandelman⁵³, C. Garcia⁵⁵, Ph. Gavillet¹⁰, E. Gazis³⁴, R. Gokieli¹⁰^,58, B. Golob⁴⁵^,47, G. Gomez-Ceballos⁴³, P. Goncalves²⁴, E. Graziani⁴¹, G. Grosdidier²², K. Grzelak⁵⁸, J. Guy³⁹, C. Haag¹⁹, A. Hallgren⁵⁴, K. Hamacher⁶⁰, K. Hamilton³⁷, S. Haug³⁵, F. Hauler¹⁹, V. Hedberg²⁸, M. Hennecke¹⁹, J. Hoffman⁵⁸, S-O. Holmgren⁴⁸, P. J. Holt¹⁰, M. A. Houlden²⁵, J. N. Jackson²⁵, G. Jarlskog²⁸, P. Jarry⁴², D. Jeans³⁷, E. K. Johansson⁴⁸, P. Jonsson²⁹, C. Joram¹⁰, L. Jungermann¹⁹, F. Kapusta²⁷, S. Katsanevas²⁹, E. Katsoufis³⁴, G. Kernel⁴⁵, B. P. Kersevan⁴⁵^,47, U. Kerzel¹⁹, B. T. King²⁵, N. J. Kjaer¹⁰, P. Kluit³³, P. Kokkinias¹³, C. Kourkoumelis⁴, O. Kouznetsov¹⁸, Z. Krumstein¹⁸, M. Kucharczyk²⁰, J. Lamsa¹, G. Leder⁵⁷, F. Ledroit¹⁶, L. Leinonen⁴⁸, R. Leitner³², J. Lemonne³, V. Lepeltier²², T. Lesiak²⁰, W. Liebig⁶⁰, D. Liko⁵⁷, A. Lipniacka⁴⁸, J. H. Lopes⁵³, J. M. Lopez³⁶, D. Loukas¹³, P. Lutz⁴², L. Lyons³⁷, J. MacNaughton⁵⁷, A. Malek⁶⁰, S. Maltezos³⁴, F. Mandl⁵⁷, J. Marco⁴³, R. Marco⁴³, B. Marechal⁵³, M. Margoni³⁸, J-C. Marin¹⁰, C. Mariotti¹⁰, A. Markou¹³, C. Martinez-Rivero⁴³, J. Masik¹⁴, N. Mastroyiannopoulos¹³, F. Matorras⁴³, C. Matteuzzi³¹, F. Mazzucato³⁸, M. Mazzucato³⁸, R. Mc Nulty²⁵, C. Meroni³⁰, E. Migliore⁴⁹, W. Mitaroff⁵⁷, U. Mjoernmark²⁸, T. Moa⁴⁸, M. Moch¹⁹, K. Moenig¹⁰, R. Monge¹⁵, J. Montenegro³³, D. Moraes⁵³, S. Moreno²⁴, P. Morettini¹⁵, U. Mueller⁶⁰, K. Muenich⁶⁰, M. Mulders³³, L. Mundim⁸, W. Murray³⁹, B. Muryn²¹, G. Myatt³⁷, T. Myklebust³⁵, M. Nassiakou¹³, F. Navarria⁶, K. Nawrocki⁵⁸, S. Nemecek¹⁴, R. Nicolaidou⁴², M. Nikolenko¹¹^,18, A. Oblakowska-Mucha²¹, V. Obraztsov⁴⁴, A. Olshevski¹⁸, A. Onofre²⁴, R. Orava¹⁷, K. Osterberg¹⁷, A. Ouraou⁴², A. Oyanguren⁵⁵, M. Paganoni³¹, S. Paiano⁶, J. P. Palacios²⁵, H. Palka²⁰, Th. D. Papadopoulou³⁴, L. Pape¹⁰, C. Parkes²⁶, F. Parodi¹⁵, U. Parzefall¹⁰, A. Passeri⁴¹, O. Passon⁶⁰, L. Peralta²⁴, V. Perepelitsa⁵⁶^,55, A. Perrotta⁶, A. Petrolini¹⁵, J. Piedra⁴³, L. Pieri⁴¹, F. Pierre⁴², M. Pimenta²⁴, E. Piotto¹⁰, T. Podobnik⁴⁵^,47, V. Poireau¹⁰, M. E. Pol⁷, G. Polok²⁰, V. Pozdniakov¹⁸, N. Pukhaeva¹⁸, A. Pullia³¹, D. Radojicic³⁷, P. Rebecchi¹⁰, J. Rehn¹⁹, D. Reid³³, R. Reinhardt⁶⁰, P. Renton³⁷, F. Richard²², J. Ridky¹⁴, M. Rivero⁴³, D. Rodriguez⁴³, A. Romero⁴⁹, P. Ronchese³⁸, P. Roudeau²², T. Rovelli⁶, V. Ruhlmann-Kleider⁴², D. Ryabtchikov⁴⁴, A. Sadovsky¹⁸, L. Salmi¹⁷, J. Salt⁵⁵, C. Sander¹⁹, A. Savoy-Navarro²⁷, U. Schwickerath¹⁰, R. Sekulin³⁹, M. Siebel⁶⁰, A. Sisakian¹⁸, G. Smadja²⁹, O. Smirnova²⁸, A. Sokolov⁴⁴, A. Sopczak²³, R. Sosnowski⁵⁸, T. Spassov¹⁰, M. Stanitzki¹⁹, A. Stocchi²², J. Strauss⁵⁷, B. Stugu⁵, M. Szczekowski⁵⁸, M. Szeptycka⁵⁸, T. Szumlak²¹, T. Tabarelli³¹, F. Tegenfeldt⁵⁴, J. Timmermans³³^*, L. Tkatchev¹⁸, M. Tobin²⁵, S. Todorovova¹⁴, B. Tome²⁴, A. Tonazzo³¹, P. Tortosa⁵⁵, P. Travnicek¹⁴, D. Treille¹⁰, G. Tristram⁹, M. Trochimczuk⁵⁸, C. Troncon³⁰, M-L. Turluer⁴², I. A. Tyapkin¹⁸, P. Tyapkin¹⁸, S. Tzamarias¹³, V. Uvarov⁴⁴, G. Valenti⁶, P. Van Dam³³, J. Van Eldik¹⁰, N. van Remortel², I. Van Vulpen¹⁰, G. Vegni³⁰, F. Veloso²⁴, W. Venus³⁹, P. Verdier²⁹, V. Verzi⁴⁰, D. Vilanova⁴², L. Vitale⁵¹, V. Vrba¹⁴, H. Wahlen⁶⁰, A. J. Washbrook²⁵, C. Weiser¹⁹, D. Wicke¹⁰, J. Wickens³, G. Wilkinson³⁷, M. Winter¹¹, M. Witek²⁰, O. Yushchenko⁴⁴, A. Zalewska²⁰, P. Zalewski⁵⁸, D. Zavrtanik⁴⁶, V. Zhuravlov¹⁸, N. I. Zimin¹⁸, A. Zintchenko¹⁸ and M. Zupan¹³

¹ Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011-3160, USA
² Physics Department, Universiteit Antwerpen, Universiteitsplein 1, 2610, Antwerpen, Belgium
³ IIHE, ULB-VUB, Pleinlaan 2, 1050, Brussels, Belgium
⁴ Physics Laboratory, University of Athens, Solonos Str. 104, 10680, Athens, Greece
⁵ Department of Physics, University of Bergen, Allégaten 55, 5007, Bergen, Norway
⁶ Dipartimento di Fisica, Università di Bologna and INFN, Viale C. Berti Pichat 6/2, 40127, Bologna, Italy
⁷ Centro Brasileiro de Pesquisas Físicas, rua Xavier Sigaud 150, 22290, Rio de Janeiro, Brazil
⁸ Inst. de Física, Univ. Estadual do Rio de Janeiro, rua São Francisco Xavier 524, Rio de Janeiro, Brazil
⁹ Collège de France, Lab. de Physique Corpusculaire, IN2P3-CNRS, 75231, Paris Cedex 05, France
¹⁰ CERN, 1211, Geneva 23, Switzerland
¹¹ Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, 67037, Strasbourg Cedex 2, France
¹² DESY-Zeuthen, Platanenallee 6, 15735, Zeuthen, Germany
¹³ Institute of Nuclear Physics, N.C.S.R. Demokritos, P.O. Box 60228, 15310, Athens, Greece
¹⁴ FZU, Inst. of Phys. of the C.A.S. High Energy Physics Division, Na Slovance 2, 182 21, Praha 8, Czech Republic
¹⁵ Dipartimento di Fisica, Università di Genova and INFN, Via Dodecaneso 33, 16146, Genova, Italy
¹⁶ Institut des Sciences Nucléaires, IN2P3-CNRS, Université de Grenoble 1, 38026, Grenoble Cedex, France
¹⁷ Helsinki Institute of Physics and Department of Physical Sciences, University of Helsinki, P.O. Box 64, 00014, Helsinki, Finland
¹⁸ Joint Institute for Nuclear Research, Dubna, Head Post Office, P.O. Box 79, 101 000, Moscow, Russian Federation
¹⁹ Institut für Experimentelle Kernphysik, Universität Karlsruhe, Postfach 6980, 76128, Karlsruhe, Germany
²⁰ Institute of Nuclear Physics PAN, Ul. Radzikowskiego 152, 31142, Krakow, Poland
²¹ Faculty of Physics and Nuclear Techniques, University of Mining and Metallurgy, 30055, Krakow, Poland
²² LAL, Univ Paris-Sud, CNRS/IN2P3, Orsay, France
²³ School of Physics and Chemistry, University of Lancaster, Lancaster, LA1 4YB, UK
²⁴ LIP, IST, FCUL - Av. Elias Garcia, 14-1º, 1000, Lisboa Codex, Portugal
²⁵ Department of Physics, University of Liverpool, P.O. Box 147, Liverpool, L69 3BX, UK
²⁶ Dept. of Physics and Astronomy, Kelvin Building, University of Glasgow, Glasgow, G12 8QQ, UK
²⁷ LPNHE, IN2P3-CNRS, Univ. Paris VI et VII, Tour 33 (RdC), 4 place Jussieu, 75252, Paris Cedex 05, France
²⁸ Department of Physics, University of Lund, Sölvegatan 14, 223 63, Lund, Sweden
²⁹ IPNL, IN2P3-CNRS, Université Claude Bernard de Lyon, 69622, Villeurbanne Cedex, France
³⁰ Dipartimento di Fisica, Università di Milano and INFN-MILANO, Via Celoria 16, 20133, Milan, Italy
³¹ Dipartimento di Fisica, Univ. di Milano-Bicocca and INFN-MILANO, Piazza della Scienza 3, 20126, Milan, Italy
³² IPNP of MFF, Charles Univ., Areal MFF, V Holesovickach 2, 180 00, Praha 8, Czech Republic
³³ NIKHEF, Postbus 41882, 1009 DB, Amsterdam, The Netherlands
³⁴ Physics Department, National Technical University, Zografou Campus, 15773, Athens, Greece
³⁵ Physics Department, University of Oslo, Blindern, 0316, Oslo, Norway
³⁶ Dpto. Fisica, Univ. Oviedo, Avda. Calvo Sotelo s/n, 33007, Oviedo, Spain
³⁷ Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK
³⁸ Dipartimento di Fisica, Università di Padova and INFN, Via Marzolo 8, 35131, Padua, Italy
³⁹ Rutherford Appleton Laboratory, Chilton, Didcot, OX11 OQX, UK
⁴⁰ Dipartimento di Fisica, Università di Roma II and INFN, Tor Vergata, 00173, Rome, Italy
⁴¹ Dipartimento di Fisica, Università di Roma III and INFN, Via della Vasca Navale 84, 00146, Rome, Italy
⁴² DAPNIA/Service de Physique des Particules, CEA-Saclay, 91191, Gif-sur-Yvette Cedex, France
⁴³ Instituto de Fisica de Cantabria (CSIC-UC), Avda. los Castros s/n, 39006, Santander, Spain
⁴⁴ Inst. for High Energy Physics, Serpukov P.O. Box 35, Protvino (Moscow Region), Russian Federation
⁴⁵ J. Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
⁴⁶ Laboratory for Astroparticle Physics, University of Nova Gorica, Kostanjeviska 16a, 5000, Nova Gorica, Slovenia
⁴⁷ Department of Physics, University of Ljubljana, 1000, Ljubljana, Slovenia
⁴⁸ Fysikum, Stockholm University, Box 6730, 113 85, Stockholm, Sweden
⁴⁹ Dipartimento di Fisica Sperimentale, Università di Torino and INFN, Via P. Giuria 1, 10125, Turin, Italy
⁵⁰ INFN, Sezione di Torino and Dipartimento di Fisica Teorica, Università di Torino, Via Giuria 1, 10125, Turin, Italy
⁵¹ Dipartimento di Fisica, Università di Trieste and INFN, Via A. Valerio 2, 34127, Trieste, Italy
⁵² Istituto di Fisica, Università di Udine and INFN, 33100, Udine, Italy
⁵³ Univ. Federal do Rio de Janeiro, C.P. 68528 Cidade Univ., Ilha do Fundão, 21945-970, Rio de Janeiro, Brazil
⁵⁴ Department of Radiation Sciences, University of Uppsala, P.O. Box 535, 751 21, Uppsala, Sweden
⁵⁵ IFIC, Valencia-CSIC, and D.F.A.M.N., U. de Valencia, Avda. Dr. Moliner 50, 46100, Burjassot (Valencia), Spain
⁵⁶ On leave of absence from: ITEP, 117259, Moscow, Russian Federation
⁵⁷ Institut für Hochenergiephysik, Österr. Akad. d. Wissensch., Nikolsdorfergasse 18, 1050, Vienna, Austria
⁵⁸ Inst. Nuclear Studies and University of Warsaw, Ul. Hoza 69, 00681, Warsaw, Poland
⁵⁹ University of Warwick, Coventry, CV4 7AL, UK
⁶⁰ Fachbereich Physik, University of Wuppertal, Postfach 100 127, 42097, Wuppertal, Germany

^* e-mail: jan.timmermans@cern.ch

Received: 1 July 2009
Revised: 17 March 2010
Published online: 22 April 2010

Abstract

An analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics (momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behavior to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences. However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the jet neutral multiplicity suggest that the rate is proportional to the number of quark pairs produced in the fragmentation process, with the neutral pairs being more effectively radiating than the charged ones.

Present address: University of Warwick, Coventry, CV4 7AL, UK

Present address: DESY-Zeuthen, Platanenallee 6, 15735, Zeuthen, Germany

© Springer-Verlag / Società Italiana di Fisica, 2010