Minutes for CEPC Flavor White Paper Discussion
Date: 2022.12.08 10:30-12:00 (Beijing time)
Participants (12): Tao Liu, Lorenzo, Liming Zhang, Lingfeng Li, Anson, Yingying Li, Xuai Zhuang, Manqi Ruan, Hao Liang, Hanhua Cui, Yongfeng Zhu, Yuexin Wang
Indico page: https://indico.ihep.ac.cn/event/18498/
Talk by Hao: Measurement of Vcb from W→μνqq
- Need further comparison with FCC (the fundamental difference?)
- Signal efficiency & purity
- Full simulation results
- Assumption of flavor tagging
- Luminosity, etc.
- Anticipated precision of Vcb should at 1% level
- Possibility to measure Vcb via full hadronic decay?
- May provide additional information, but challenging (e.g. jet confusion)
- Corresponding accuracy unlikely overwhelms the semileptonic one (which is much easier to handle)
- Using information at event level instead of jet level analysis
- We always lose some message at jet level analysis
- Hao proposes to use neural network with particle level information as inputs
- Using truth level particles as first step
- Flavor tagging efficiency should be a function, instead of using the average efficiency
- Dependence on the jet energy/PT/polar angle, etc.
- Efficiency of W→cb different from that of W→c(s/d) or W→u(s/d)
- Possible reason: the missing PT cut or the MC uncertainty?
- The missing PT cut may cause systematics
Talk by Hanhua: Jet charge measurement at CEPC
- To further understand the fragmentation method of different generators
- The only difference of different generators is the hadronization and the parton shower
- To quantify the possible correlation induced by hard gluon emission
- Look into the dependence on some jet shape parameters (like thrust, Y23, etc.)
- Also plan to look into the dependence of jet charge performance on the ECM
- Muon has the biggest difference
- Maybe hadron decay should be taken into account
- b cascading
- Benchmark applications
- All CP violation related measurements
- Some new physics may be also sensitive to the jet charge
- Current two methods (Leading Particle & Weighted Charge)
- Weighted Charge: the traditional one, dominate the b-performance
- Leading Particle: only use one dimensional information
- Suggest to explore other more methods to include more information (like 2nd/3rd vertex), all the LEP methods can be a good reference to start with
- Worry about correlations between multiple methods when combining them
- Suggest at least 3 subcategories (B0, Bs, Λb, only the neutral ones need to be tagged)
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