Test of QCD analytic predictions for the multiplicity ratio between gluon and quark jets

Abstract Gluon jets with about 39 GeV energy are identified in hadronic Z 0 decays by tagging two jets in the same hemisphere of an event as quark jets. Identifying the gluon jet to be all the particles observed in the hemisphere opposite to that containing the two tagged jets yields an inclusive gluon jet definition corresponding to that used in analytic calculations, allowing the first direct test of those calculations. In particular, this jet definition yields results which are only weakly dependent on a jet finding algorithm. We find r ch. =1.552±0.0041 ( stat ) ±0.061 ( syst. ) for the ratio of the mean charged particle multiplicity in gluon jets to that in light quark uds jets, where the uds jets are identified using an inclusive jet definition similar to that used for the gluon jets. Our result is in general agreement with the prediction of a recent analytic calculation which incorporates energy conservation into the parton shower branching processes, but is considerably smaller than analytic predictions which do not incorporate energy conservation.

Jean-Arcady Meyer | John S. White | T. Geralis | C. Hajdu | Paolo Capiluppi | G. M. Dallavalle | C. Grandi | S. Marcellini | A. Montanari | G. P. Siroli | Frans Meijers | C. H. Shepherd-Themistocleous | Peter R Hobson | D. Lazic | G. G. Hanson | J. Letts | M. D. Hildreth | P. Schütz | J. M. Roney | H. Lafoux | Jeroan J. Allison | Andris Skuja | Otmar Biebel | Klaus Kurt Desch | T. Kress | M. Schröder | D. R. Ward | T. G. Shears | R. J. Barlow | S. Tarem | B. Schmitt | D. R. Rust | Silvia Arcelli | V. Gibson | C. R. Jones | Carla Sbarra | Hans-Christian Schultz-Coulon | F. K. Loebinger | I. Cohen | Yoram Rozen | Stefan Schmitt | Daniel Lellouch | Giora Mikenberg | Danny Miller | Kiyotomo Kawagoe | Robert Victor Kowalewski | Christopher Hawkes | Eilam Gross | Stephen Hillier | Joleen Pater | Markus Schumacher | Pauline Gagnon | Gideon Alexander | Peter Sherwood | Lorne Levinson | Randall Sobie | Stephen Lloyd | Gideon Bella | Richard Nisius | Georges Azuelos | Janet Carter | Christoph Geich-Gimbel | Tetsuro Mashimo | Richard Keeler | Derek Strom | Carlo Dallapiccola | T. Kawamoto | J. Pálinkás | Paul M. Schenk | Franco Strumia | S. A. Wotton | K. W. Bell | J. E.G. Edwards | Michael Hauschild | J. von Krogh | F. Fiedler | P. Jovanovic | W. G. Scott | R. Giacomelli | M. Hapke | S. W. O'Neale | G. Duckeck | G. Wolf | M. J. Goodrick | Sachio Komamiya | N. Wermes | A. N. Bell | R. Bartoldus | P. Vikas | I. Nakamura | Helfried Burckhart | A. S. Turcot | M. J. Losty | J. C. Hill | A. K. Honma | P. G. Estabrooks | M. Rosvick | I. P. Duerdoth | D. Glenzinski | G. Herten | J. S. 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