Download
1 / 18
180 likes | 279 Vues
Delve into the significance of rare charm processes in probing new physics beyond the Standard Model, focusing on FCNC decay and mixing phenomena sensitive to supersymmetry effects. Discusses implications for future experiments such as BESIII and potential enhancements in decay rates.
E N D
Rare Charm Processes and Supersymmetry Kwong Lau University of Houston PRC-US Workshop Beijing, June 11-18, 2006
Outline of talk • Why are rare charm processes important in searching for new physics outside the Standard Model? • Why rare charm processes are sensitive to supersymmetry? • Two benchmark charm rare processes: FCNC decay D0 -> m+m- and D0 mixing • Prospects at BES III • Summary
General Comments • Rare charm processes proceed in the Standard Model via box diagrams in the short distance limit • The GIM mechanism suppresses FCNC in the Standard model • The GIM mechanism is broken by non-degenerate quark masses • The FCNC box amplitude in the charm sector is undetectably small because of the smallness and/or degeneracy of the quark masses in the down-type quarks (d, s, and b) • Supersymmetric quarks (squarks) and wino can contribute to the box amplitude, and dominate if the squarks masses are not degenerate • Squark masses are a priori not degenerate unless there is additional symmetry • Fractional squark mass differences at O(10-3-10-4) will enhance the box amplitudes to a detectable level. • For example, the CCNC decay D mm branching ratio can be enhanced to 10-10 level • The purpose of this talk is to explore the relationship between the two main CCNC processes (rare decay and mixing) in the context of a generic supersymmetric model
The effective CCNC amplitude m c m Reference: Inami and Lim, NPB 207, 533 (1982).
CCNC predictions The two rare processes share common parameters through the C and E functions. One can do a parametric study by evaluating both process numerically as a function of model parameters (assumed free).
D -> mm decay rate in supersymmetric models Supersymmetric particles with natural mass differences (O(10-3)) can boost the rare D -> mm decay rate by 6-7 orders of magnitude
D0 mixing rate in supersymmetric models Supersymmetric particles with natural mass differences (O(10-3)) can boost the D mixing rate by 6-7 orders of magnitude
FCNC decay searches in E771 High rate hadroproduction of D0’s at hadron colliders and precision vertex measurement of D0 decays are both necessary, a challenging task.
Prospects at BESIII • BESIII expects to produce a few x 107 D0’s per year • It is unlikely that BESIII can improve the D0->mm limit • BESIII can reconstruct a large sample of low-multiplicity D0 decays, e.g., D0 -> Kp decays to search for mixing • The fact that D0’s are produced at threshold at BESIII is a challenge
D0 mixing vs D -> mm decay rate in supersymmetric models The next generation charm experiment at BES III can search D0 CCNC decay rates of order 10-10, probing squark mass up to TeV scale
