Search for the Rare Decay $$K_L \to \pi^0 \pi^0 \mu^+ \mu^-$$
- Univ. of Virginia, Charlottesville, VA (United States)
This thesis describes the search for KL → π0π0μ+μ-, which was conducted using data collected by the KTeV Experiment at Fermi National Accelerator Laboratory in Batavia, Illinois. Although this decay mode is possible within the Standard Model, it is limited to a very narrow band of phase space. The HyperCP Experiment has recently observed three Σ+ → pμ+μ- events within a narrow dimuon mass range of 213.8 MeV/c2 to 214.8 MeV/c2. This suggests that the process could occur via a neutral intermediary particle, Σ+ → pX0 → pμ+μ-, with an X0 mass of 214.3 MeV/c2 ± 0.5 MeV/c2 . Since the X0 has a light mass and a low interaction probability, then it is most likely a new neutral boson that exists beyond the Standard Model. Recent theoretical predictions suggest that the decay mode KL → π0π0μ+μ- can also occur via the aforementioned neutral boson: KL → π0π0X0→ π0π0μ+μ-. Therefore, in addition to a Standard Model measurement, the search for KL → π0π0μ+μ- is also carried out in an effort to address the viability of X0 in explaining the HyperCP phenomena. Measurement of the upper limits presented in this thesis were performed using blind analysis techniques. The upper limit of the decay KL → π0π0μ+μ- has been measured in this thesis to be BR(KL → π0π0μ+μ-) < 8.63 x 10-11 at 90% confidence level. In addition, this thesis has measured the upper limit of the decay KL → π0π0X0 → π0π0μ+μ- to be Br(KL → π0π0X0 → π0π0μ+μ-) < 9.44 x 10-11 at the 90% confidence level.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 984004
- Report Number(s):
- FERMILAB-THESIS-2009-61; TRN: US1005276
- Country of Publication:
- United States
- Language:
- English
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