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Theoretical understanding of charm decays

Description: A detailed description of charm decays has emerged. The various concepts involved are sketched. Although this description is quite successful in reproducing the data the chapter on heavy flavour decays is far from closed. Relevant questions like on th real strength of weak annihilation, Penguin operators, etc. are still unanswered. Important directions in future work, both on the experimental and theoretical side are identified.
Date: August 1, 1986
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

On charm and beauty decays: A theorist's perspective

Description: The present understanding of charm and bottom decays is reviewed. Special emphasis is placed on discussing the theoretical uncertainties in view of the particularly rich harvest of new data from the last year. A semi-quantitative description of D decays has emerged enabling us to address rather detailed and relatively subtle questions there, like on once and twice Cabibbo suppressed decays. Beauty physics having left its infancy is now in its adolescence; its future development towards maturity is analyzed.
Date: October 1, 1987
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

On weak decays of heavy flavors, mixing and CP violation

Description: Detailed studies of weak decays serve not only to confirm the Standard Model, but possess also a high sensitivity to New Physics: tau and top decays are discussed in this vein, with some short remarks on beauty and charm. The sensitivity to New Physics is even higher in delicate phenomena like mixing and CP violation: a fairly detailed discussion on K/sup 0/ - anti K/sup 0/, D/sup 0/ - anti D/sup 0/, and B/sup 0/ - anti B/sup 0/ mixing and on CP violation in K/sup 0/ and B decays is presented. 48 refs., 11 figs.
Date: October 1, 1987
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

On charm decays: Present status and future goals

Description: After a qualitative introduction into the dynamics underlying charm decays the author describes in some detail three different theoretical treatments: the Stech et al. description based on factorization, the 1/N approach and an ansatz employing QCD sum rules. The overall agreement of the emerging theoretical picture with the data is rather encouraging and indicates that the effects of hadronization on these decays are under reasonable control. Yet more and more detailed data are needed to confirm (hopefully) this simple picture. The author lists the processes most relevant in this respect and emphasizes the need for increasing our theoretical sophistication. Once this is achieved we have on one hand acquired the theoretical tools to deal with B physics; on the other hand we will then be ready to exploit charm physics to the fullest in searching for exotic D decays, D/sup 0/ - anti D/sup 0/ mixing and CP violation.
Date: June 1, 1987
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

Flavor mixing with quarks and leptons

Description: The last year has brought such a wealth of new information on heavy flavors that meaningful bounds can now be placed on all fermion mass related parameters in the Standard Model. The status of the KM matrix is reviewed with particular emphasis on the theoretical uncertainties. B/sup 0/-anti B/sup 0/ mixing is reevaluated and CP violation is discussed as it is observed in K/sub L/ decays and as it hopefully can be studied in B decays. The report is concluded with short remarks on neutrino oscillations.
Date: October 1, 1987
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

Prospects of observing CP violation in bottom and charm decays

Description: A review is given on the phenomenology of CP violation in B and D decays that has been developed over the last few years. Since a firm data base on B decays is still lacking, semiquantitative scenarios are drawn. Within the Standard Model one predicts asymmetries that can be as large as O (10%) with a confidence level that ranges between hopeful and considerable. Even so, millions of produced B and D mesons are required to make such studies feasible. A B factory would be crucial in such an endeavor. 10 refs.
Date: September 1, 1986
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

CP violation in B and D decays

Description: Non-leptonic B decays offer the best opportunity to discover the violation of CP invariance outside the neutral K system. Employing the Standard Model one predicts - with reasonable confidence - CP asymmetries of up to 205 (or even more in some cases). The branching ratios for the individual exclusive modes of interest are not expected to exceed the 10/sup -3/ level in most cases; the identification of such decays poses non-trivial problems. It is shown that by summing intelligently over appropriate classes of decays one can greatly enhance statistics without jeopardizing the signal. Data that contain 10/sup 6/ produced B mesons would allow meaningful searches for CP violation. It is noted that ''New Physics'' could lead to CP asymmetries in D/sup 0/ decays of order 1%. Due to higher branching ratios one can search for such effects in samples of 10/sup 6/ produced D mesons. 7 refs.
Date: June 1, 1986
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

Indirect serarches for very heavy quarks

Description: Detailed studies of weak decays can reveal the presence of very massive quanta like heavy top quarks or fourth family quarks. The decay K/sup +/ ..-->.. ..pi../sup +/..nu.. anti ..nu.. and B/sub d/ - anti B/sub d/ mixing are particularly promising fields for such searches. We infer a rather conservative lower limit of 70 GeV on the top mass form recent ARGUS data on B/sub d/ - anti B/sub d/ mixing, near-maximal B/sub 8/ - anti B/sub 8/ mixing is another consequence. If on the other hand top were detected in Z/sup 0/ decays, then the presence of New Physics would be established in B/sup 0/ decays. The ratio between tau(B/sup 0/) and tau(B/sup + -/) is of considerable phenomenological relevance here.
Date: March 1, 1987
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

Search for CP violation in B/sup 0/ (and D/sup 0/) decays II: A closer look

Description: Recent findings from UA1 and ARGUS on B/sup 0/ - anti B/sup 0/ mixing brighten considerably the prospects of findings CP violation in B/sup 0/ decays. We sketch some semi-quantitative scenarios where we also address technical issues like the amount of time that is necessary. We point out that searching for the reaction UPSILON(4s) ..-->.. B/sup 0/ anti B/sup 0/ ..-->.. f/sub 1/, f/sub 2/, (where f/sub x/ = line integral), where f/sub 1/, f/sub 2/ are CP eigenstates of the same CP parity has a good chance of revealing CP violation. The tight upper bound on D/sup 0/ - anti D/sup 0/ mixing, namely 0.5-1%, still allows for CP asymmetries of up to 5% in (-) D/sup 0/ ..-->.. K/sup +/K/sup -/, K/sub s/K/sup +/K/sup -/.
Date: April 1, 1987
Creator: Bigi, I.I.
Partner: UNT Libraries Government Documents Department

Non multa, sed multum: Future lessons from two-prong, two-body decays of beauty

Description: There are four two-body, two-prong decays modes of B mesons and two for beauty baryons and they are quite rare, i.e., their branching ratios are not expected to exceed the script O(10/sup -4/) level. Yet a detailed study of their relative rates with a sensitivity level of 10/sup -5/ can yield unique and important information on strong interactions. If the evolution of these reactions in proper time can be traced then, under favorable conditions, one can analyze B/sup 0/ - anti B/sup 0/ mixing and CP invariance in a detailed way. 4 refs.
Date: December 1, 1987
Creator: Bigi, I.I. & Stech, B.
Partner: UNT Libraries Government Documents Department

B, D and K Decays

Description: The present report documents the results of Working Group 2: B, D and K decays, of the workshop on Flavor in the Era of the LHC, held at CERN from November 2005 through March 2007. With the advent of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct detection of new particles will be the main avenue to establish the presence of NP at the LHC, indirect searches will provide precious complementary information, since most probably it will not be possible to measure the full spectrum of new particles and their couplings through direct production. In particular, precision measurements and computations in the realm of flavor physics are expected to play a key role in constraining the unknown parameters of the Lagrangian of any NP model emerging from direct searches at the LHC. The aim of Working Group 2 was twofold: on one hand, to provide a coherent, up-to-date picture of the status of flavor physics before the start of the LHC; on the other hand, to initiate activities on the path towards integrating information on NP from high-p{sub T} and flavor data. This report is organized as follows. In Sec. 1, we give an overview of NP models, focusing on a few examples that have been discussed in some detail during the workshop, with a short description of the available computational tools for flavor observables in NP models. Sec. 2 contains a concise discussion of the main theoretical problem in flavor physics: the evaluation of the relevant hadronic matrix elements for weak decays. Sec. 3 contains a detailed discussion of NP effects in a set of flavor observables that we identified as 'benchmark channels' for NP ...
Date: March 7, 2008
Creator: Artuso, M.; Asner, D.M.; Ball, P.; Baracchini, E.; Bell, G.; Beneke, M. et al.
Partner: UNT Libraries Government Documents Department