共查询到20条相似文献,搜索用时 15 毫秒
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Coffman D DeJongh F Dubois G Eigen G Hauser J Hitlin DG Matthews CG Mincer A Richman JD Wisniewski WJ Zhu Y Burchell M Dorfan DE Drinkard J Gatto C Hamilton RP Heusch CA Köpke L Lockman WS Partridge R Sadrozinski HF Scarlatella M Schalk TL Seiden A Weinstein AJ Weseler S Xu R Becker JJ Blaylock GT Eisenstein BI Freese T Gladding G Izen JM Plaetzer SA Simopoulos C Spadafora AL Stockdale IE Tripsas B Mallik U Roco M Wang MZ Adler J Bolton T Brient JC Bunnell KO Cassell RE Coward DH Einsweiler KF 《Physical review D: Particles and fields》1990,41(5):1410-1413
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Armstrong TA Bettoni D Bharadwaj V Biino C Borreani G Broemmelsiek D Buzzo A Calabrese R Ceccucci A Cester R Church MD Dalpiaz P Dalpiaz PF Dibenedetto R Dimitroyannis D Fabbri MG Fast JE Gianoli A Ginsburg CM Gollwitzer KE Hahn AA Hasan MA Hsueh SY Lewis RA Luppi E Macrí M Majewska AM Mandelkern MA Marchetto F Marinelli M Marques JL Marsh W Martini M Masuzawa M Menichetti E Migliori A Mussa R Palestini S Pallavicini M Pastrone N Patrignani C Peoples J Pesando L Petrucci F Pia MG Pordes S 《Physical review D: Particles and fields》1993,48(7):3037-3044
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Recent measurements by the Belle Collaboration of the exclusive production of two charmonia in e(+)e(-) annihilation differ substantially from theoretical predictions. We suggest that a significant part of the discrepancy can be explained by the process e(+)e(-)-->J/psi+J/psi. Because the J/psi+J/psi production process can proceed through fragmentation of two virtual photons into two cc pairs, its cross section may be larger than that for J/psi+eta(c) by about a factor of 3.7, in spite of a suppression factor alpha(2)/alpha(2)(s) that is associated with the QED and QCD coupling constants. 相似文献
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Double-charm production e+e- -->J/psi + cc at B factories with next-to-leading-order QCD corrections
The inclusive J/psi production in e;{+}e;{-}-->J/psicc at B factories is one of the most challenging open problems in heavy quarkonium physics. The observed cross section of this double-charm production process is larger than existing leading order (LO) QCD predictions by a factor of 5. In the nonrelativistic QCD (NRQCD) factorization formalism, we calculate the next-to-leading order (NLO) QCD virtual and real corrections to this process, and find that these corrections can substantially enhance the cross section with a K factor of about 1.8. We further take into account the feeddown contributions from higher charmonium states [mainly the psi(2S) as well as chi_{cJ}] and the two-photon contributions, and find that the discrepancy between theory and experiment can be largely removed. 相似文献
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Yuan CZ Shen CP Wang P McOnie S Adachi I Aihara H Aulchenko V Aushev T Bahinipati S Balagura V Barberio E Bedny I Bitenc U Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang MC Chang P Chen A Chen KF Chen WT Cheon BG Chistov R Cho IS Choi Y Dalseno J Danilov M Dash M Eidelman S Fratina S Gabyshev N Golob B Ha H Haba J Hayasaka K Hayashii H Hazumi M Heffernan D Hokuue T Hoshi Y Hou WS Hsiung YB Hyun HJ Iijima T Ikado K Inami K Ishikawa A Itoh R Iwasaki Y Kah DH Kaji H Kang JH Katayama N 《Physical review letters》2007,99(18):182004
The cross section for e(+)e(-)-->pi(+)pi(-)J/psi between 3.8 and 5.5 GeV/c(2) is measured using a 548 fb(-1) data sample collected on or near the Upsilon(4S) resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c(2), corresponding to the so called Y(4260), is observed. In addition, there is another cluster of events at around 4.05 GeV/c(2). A fit using two interfering Breit-Wigner shapes describes the data better than one that uses only the Y(4260), especially for the lower-mass side of the 4.25 GeV enhancement. 相似文献
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Abouzaid E Arenton M Barker AR Bellantoni L Blucher E Bock GJ Cheu E Coleman R Corcoran MD Cox B Erwin AR Glazov A Golossanov A Hsiung YB Jensen DA Kessler R Kobrak HG Kotera K LaDue J Ledovskoy A McBride PL Monnier E Nguyen H Niclasen R Ramberg EJ Ray RE Ronquest M Shields J Slater W Smith D Solomey N Swallow EC Toale PA Tschirhart R Wah YW Wang J White HB Whitmore J Wilking MJ Winston R Worcester ET Yamanaka T Zimmerman ED 《Physical review letters》2007,99(5):051804
The E799-II (KTeV) experiment at Fermilab has collected 83 262 K(L)-->e+ e- gamma(gamma) events above a background of 79 events. We measure a decay width, normalized to the K(L)-->pi0pi0pi(D)0 (pi0-->gammagamma, pi0-->gammagamma, pi(D0-->e+ e- gamma(gamma)) decay width, of Gamma(K(L)-->e+e-gamma(gamma))/Gamma(K(L)-->pi0pi0pi(D)0)=(1.3302+/-0.0046(stat)+/-0.0102(syst)) x 10(-3). We also measure parameters of two K(L)gamma*gamma form factor models. In the Bergstr?m-Massó-Singer parametrization, we find Calpha(K*)= -0.517 +/- 0.030(stat) +/- 0.022(syst). We separately fit for the first parameter of the D'Ambrosio-Isidori-Portolés model and find alpha(DIP)= -1.729 +/- 0.043(stat) +/- 0.028(syst). 相似文献
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Baltrusaitis RM Becker JJ Blaylock GT Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Cui H Del Papa C Dorfan DE Duncan AL Einsweiler KF Eisenstein BI Fabrizio R Gladding G Grancagnolo F Hamilton RP Hauser J Heusch CA Hitlin DG Köpke L Mockett PM Moss L Mozley RF Nappi A Odian A Partridge R Perrier J Plaetzer SA Richman JD Roehrig JR Russell JJ Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Sleeman JC Spadafora AL Thaler JJ Toki W Unno Y Villa F Wattenberg A 《Physical review letters》1985,55(17):1723-1726
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Bolton RD Bowman JD Cooper MD Frank JS Hallin AL Heusi PA Hoffman CM Hogan GE Mariam FG Matis HS Mischke RE Nagle DE Piilonen LE Sandberg VD Sanders GH Sennhauser U Werbeck R Williams RA Wilson SL Hofstadter R Hughes EB Ritter MW Grosnick D Wright SC Highland VL McDonough J 《Physical review letters》1986,56(23):2461-2464
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Grosnick D Wright SC Bolton RD Cooper MD Frank JS Hallin AL Heusi PA Hoffman CM Hogan GE Mariam FG Matis HS Mischke RE Piilonen LE Sandberg VD Sanders GH Sennhauser U Werbeck R Williams RA Wilson SL Hofstadter R Hughes EB Ritter MW Highland VL McDonough J 《Physical review letters》1986,57(26):3241-3244
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Bolton T Brown JS Bunnell KO Burchell M Burnett TH Cassell RE Coffman D Coward DH Coyle P DeJongh F Drinkard J Dubois GP Eigen G Eisenstein BI Freese T Gatto C Gladding G Heusch CA Hitlin DG Izen JM Kim PC Labs J Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Odian A Parrish L Pitman D Richman JD Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Stockdale IE Toki W Tripsas B Wang MZ Weinstein AJ Weseler S Willutzki HJ Wisniewski WJ Xu R Zhu Y 《Physical review letters》1992,69(9):1328-1331
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Adler J Becker JJ Blaylock GT Bolton T Brient JC Brown JS Bunnell KO Burchell M Burnett TH Cassell RE Coffman D Cook V Coward DH Dorfan DE Drinkard J Dubois GP Duncan AL Eigen G Einsweiler KF Eisenstein BI Freese T Gatto C Gladding G Grab C Hamilton RP Hauser J Heusch CA Hitlin DG Izen JM Köpke L Li A Lockman WS Mallik U Matthews CG Mincer A Mir R Mockett PM Mozley RF Nemati B Odian A Parrish L Partridge R Perrier J Pitman D Plaetzer SA Richman JD Sadrozinski HF Scarlatella M Schalk TL 《Physical review D: Particles and fields》1989,40(11):3788
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Adler J Becker JJ Blaylock GT Bolton T Brient JC Brown JS Bunnell KO Burchell M Burnett TH Cassell RE Coffman D Cook V Coward DH DeJongh F Dorfan DE Drinkard J Dubois GP Eigen G Einsweiler KF Eisenstein BI Freese T Gatto C Gladding G Grab C Hamilton RP Hauser J Heusch CA Hitlin DG Izen JM Kim PC Köpke L Li A Lockman WS Mallik U Matthews CG Mincer A Mir R Mockett PM Nemati B Odian A Parrish L Partridge R Pitman D Plaetzer SA Richman JD Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A 《Physical review D: Particles and fields》1989,40(3):906-908
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Alavi-Harati A Albuquerque IF Alexopoulos T Arenton M Arisaka K Averitte S Barker AR Bellantoni L Bellavance A Belz J Ben-David R Bergman DR Blucher E Bock GJ Bown C Bright S Cheu E Childress S Coleman R Corcoran MD Corti G Cox B Crisler MB Erwin AR Ford R Fordyce PM Glazov A Golossanov A Graham G Graham J Hagan K Halkiadakis E Hanagaki K Hidaka S Hsiung YB Jejer V Jennings J Jensen DA Kessler R Kobrak HG LaDue J Lath A Ledovskoy A McBride PL McManus AP Mikelsons P Monnier E Nakaya T Nelson KS 《Physical review letters》2001,86(3):397-401
We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) at the 90% confidence level. 相似文献