Radiative Penguin Decays at the B Factories
The flavor-changing neutral current transitions b → s and b → d cannot proceed at the tree level in the Standard Model (SM). Radiative decays such as B → Xsγ , B → Xdγ and B → Xsll hence proceed primarily via one-loop diagrams known as penguin and box diagrams. Because of this, these processes are rare in the SM, with branching ratios on the order of 10 to 10. However, for the same reason, these channels are very sensitive to new physics beyond the SM. In the past few years, the B Factory detectors, Belle at the KEKB collider at KEK, Japan and BABAR at the PEP-II collider at SLAC, U.S.A., have recorded a total of more than 0.9 ab of data, making it possible to study these decays extensively. Both experiments benefit from high-granularity electromagnetic calorimetry with excellent angular and energy resolution (∼ 3% for 1 GeVphotons), silicon vertex detectors providing position resolution on the order of 100 μmalong the beam axis and K/π separation for momenta up to 3-4 GeV. Details of the detectors can be found in references [1]. The relevant theoretical framework for all the decays reviewed in this paper is the operator product expansion (OPE) [2], with which the heavy particles (the gauge bosons and the top quark in the SM) are integrated out to obtain an effective low-energy theory with five quarks. The long-distance contributions are captured in operator matrix elements, whereas the short-distance physics is described by the effective coupling constants, known as Wilson coefficients. Physics beyond the SM can manifest in new operators, or in vastly different values for the Wilson coefficients of the existing operators, compared to the SM predictions. The OPE framework provides parton-level predictions, so the connection to the experimental observables require further non-perturbative corrections. Form factors, calculations of which introduce significant theoretical uncertainties, are needed to study exclusive final states (B → K γ , B → Kll , etc.). On the other hand, for inclusive decays, heavy-quark expansion (HQE) and quark-hadron duality keep nonperturbative corrections under control. This allows more direct interpretations of the measurements of the inclusive decay rates. However, exclusive decays, being experimentally cleaner, are observed earlier and measured with better precision. Ratios of exclusivedecay observables, in which the form-factor corrections partially or completely cancel, can also provide complimentary information to that obtained from inclusive decays.
Measurement of Branching Fractions and Mass Spectra of B→Kππγ
B. Aubert, R. Barate, D. Boutigny, F. Couderc, Y. Karyotakis, J. P. Lees, V. Poireau, V. Tisserand, A. Zghiche, E. Grauges, A. Palano, M. Pappagallo, A. Pompili, J. C. Chen, N. D. Qi, G. Rong, P. Wang, Y. S. Zhu, G. Eigen, I. Ofte, B. Stugu, G. S. Abrams, M. Battaglia, A. B. Breon, D. N. Brown, J. Button-Shafer, R. N. Cahn, E. Charles, C. T. Day, M. S. Gill, A. V. Gritsan, Y. Groysman, R. G. Jacobsen, R. W. Kadel, J. Kadyk, L. T. Kerth, Yu. G. Kolomensky, G. Kukartsev, G. Lynch, L. M. Mir, P. J. Oddone, T. J. Orimoto, M. Pripstein, N. A. Roe, M. T. Ronan, W. A. Wenzel, M. Barrett, K. E. Ford, T. J. Harrison, A. J. Hart, C. M. Hawkes, S. E. Morgan, A. T. Watson, M. Fritsch, K. Goetzen, T. Held, H. Koch, B. Lewandowski, M. Pelizaeus, K. Peters, T. Schroeder, M. Steinke, J. T. Boyd, J. P. Burke, N. Chevalier, W. N. Cottingham, M. P. Kelly, T. Cuhadar-Donszelmann, B. G. Fulsom, C. Hearty, N. S. Knecht, T. S. Mattison, J. A. McKenna, A. Khan, P. Kyberd, M. Saleem, L. Teodorescu, A. E. Blinov, V. E. Blinov, A. D. Bukin, V. P. Druzhinin, V. B. Golubev, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, A. N. Yushkov, D. Best, M. Bondioli, M. Bruinsma, M. Chao, I. Eschrich, D. Kirkby, A. J. Lankford, M. Mandelkern, R. K. Mommsen, W. Roethel, D. P. Stoker, C. Buchanan, B. L. Hartfiel, S. D. Foulkes, J. W. Gary, O. Long, B. C. Shen, K. Wang, L. Zhang, D. del Re, H. K. Hadavand, E. J. Hill, D. B. MacFarlane, H. P. Paar, S. Rahatlou, V. Sharma, J. W. Berryhill, C. Campagnari, A. Cunha, B. Dahmes, T. M. Hong, M. A. Mazur, J. D. Richman, W. Verkerke, T. W. Beck, A. M. Eisner, C. J. Flacco, C. A. Heusch, J. Kroseberg, W. S. Lockman, G. Nesom, T. Schalk, B. A. Schumm, A. Seiden, P. Spradlin, D. C. Williams, M. G. Wilson, J. Albert, E. Chen, G. P. Dubois-Felsmann, A. Dvoretskii, D. G. Hitlin, I. Narsky, T. Piatenko, F. C. Porter, A. Ryd, A. Samuel, R. Andreassen, S. Jayatilleke, G. Mancinelli, B. T. Meadows, M. D. Sokoloff, F. Blanc, P. Bloom, S. Chen, W. T. Ford, U. Nauenberg, A. Olivas, P. Rankin, W. O. Ruddick, J. G. Smith, K. A. Ulmer, S. R. Wagner, J. Zhang, A. Chen, E. A. Eckhart, A. Soffer, W. H. Toki, R. J. Wilson, Q. Zeng, D. Altenburg, E. Feltresi, A. Hauke, B. Spaan, T. Brandt, J. Brose, M. Dickopp, V. Klose, H. M. Lacker, R. Nogowski, S. Otto, A. Petzold, G. Schott, J. Schubert, K. R. Schubert, R. Schwierz, J. E. Sundermann, D. Bernard, G. R. Bonneaud, P. Grenier, S. Schrenk, Ch. Thiebaux, G. Vasileiadis, M. Verderi, D. J. Bard, P. J. Clark, W. Gradl, F. Muheim, S. Playfer, Y. Xie, M. Andreotti, V. Azzolini, D. Bettoni, C. Bozzi, R. Calabrese, G. Cibinetto, E. Luppi, M. Negrini, L. Piemontese, F. Anulli, R. Baldini-Ferroli, A. Calcaterra, R. de Sangro, G. Finocchiaro, P. Patteri, I. M. Peruzzi,* M. Piccolo, A. Zallo, A. Buzzo, R. Capra, R. Contri, M. Lo Vetere, M. Macri, M. R. Monge, S. Passaggio, C. Patrignani, E. Robutti, A. Santroni, S. Tosi, S. Bailey, G. Brandenburg, K. S. Chaisanguanthum, M. Morii, E. Won, J. Wu, R. S. Dubitzky, U. Langenegger, J. Marks, S. Schenk, U. Uwer, W. Bhimji, D. A. Bowerman, P. D. Dauncey, U. Egede, R. L. Flack, J. R. Gaillard, G. W. Morton, J. A. Nash, M. B. Nikolich, G. P. Taylor, W. P. Vazquez, M. J. Charles, W. F. Mader, U. Mallik, A. K. Mohapatra, J. Cochran, H. B. Crawley, V. Eyges, W. T. Meyer, S. Prell, E. I. Rosenberg, A. E. Rubin, J. Yi, N. Arnaud, M. Davier, X. Giroux, G. Grosdidier, A. Höcker, F. Le Diberder, V. Lepeltier, A. M. Lutz, A. Oyanguren, T. C. Petersen, M. Pierini, S. Plaszczynski, S. Rodier, P. Roudeau, M. H. Schune, A. Stocchi, G. Wormser, C. H. Cheng, D. J. Lange, M. C. Simani, D. M. Wright, A. J. Bevan, C. A. Chavez, J. P. Coleman, I. J. Forster, J. R. Fry, E. Gabathuler, R. Gamet, K. A. George, D. E. Hutchcroft, R. J. Parry, D. J. Payne, K. C. Schofield, C. Touramanis, C. M. Cormack, F. Di Lodovico, R. Sacco, C. L. Brown, G. Cowan, H. U. Flaecher, M. G. Green, D. A. Hopkins, P. S. Jackson, T. R. McMahon, S. Ricciardi, F. Salvatore, D. Brown, C. L. Davis, J. Allison, N. R. Barlow, R. J. Barlow, M. C. Hodgkinson, G. D. Lafferty, M. T. Naisbit, J. C. Williams, C. Chen, A. Farbin, W. D. Hulsbergen, A. Jawahery, D. Kovalskyi, C. K. Lae, V. Lillard, D. A. Roberts, G. Simi, G. Blaylock, C. Dallapiccola, S. S. Hertzbach, R. Kofler, V. B. Koptchev, X. Li, T. B. Moore, S. Saremi, H. Staengle, S. Willocq, R. Cowan, K. Koeneke, G. Sciolla, S. J. Sekula, M. Spitznagel, F. Taylor, R. K. Yamamoto, H. Kim, P. M. Patel, S. H. Robertson, A. Lazzaro, V. Lombardo, F. Palombo, J. M. Bauer, L. Cremaldi, V. Eschenburg, R. Godang, R. Kroeger, J. Reidy, D. A. Sanders, D. J. Summers, H. W. Zhao, S. Brunet, D. Côté, P. Taras, B. Viaud, H. Nicholson, N. Cavallo, G. De Nardo, F. Fabozzi, C. Gatto, L. Lista, D. Monorchio, P. Paolucci, D. Piccolo, C. Sciacca, M. Baak, H. Bulten, G. Raven, H. L. Snoek, L. Wilden, C. P. Jessop, J. M. LoSecco, T. Allmendinger, G. Benelli, K. K. Gan, K. Honscheid, D. Hufnagel, PRL 98, 211804 (2007) P H Y S I C A L R E V I E W L E T T E R S week ending 25 MAY 2007
Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel
The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.