Z-Factory Physics. Physics for Modernized Z-Factory. Chao-Hsi Chang (Zhao-Xi Zhang) ITP, CAS

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1 Z-Factory Physics Physics for Modernized Z-Factory Chao-Hsi Chang (Zhao-Xi Zhang) ITP, CAS --- Working Group for Z-factory Physics --- Group WeiHai The topics for Z-factory Physics July 13-17, 2011 Modenized Z-Factory 1

2 The modernlized Z-factory The Z-Factories: The old ones LEP-I: L 0 = 2.4 ê cm -2 s -1 SLC: L 0 = 0.6 ê cm -2 s -1 The modernized ones: L =10 3~4 L 0 even higher 10 10~11 Z/year and etc The modernized factory is accessible in technique ( modernized is based on the present techniques) The techniques in e + e - collider are in progress greatly! e.g. Super B-factory: L 10 35~36 cm -2 s -1 ILC: L >10 34 cm -2 s -1 July 13-17, 2011 Modenized Z-Factory 2

3 Physics for Modernized Z-Factory The Physics Topics for a Modern Z-Factory (Theoretical considerations mainly so far) A. Z boson properties (Precision Test SM & New Physics) B. c, b-hadron physics (QCD & New Physics) C.τ lepton physics (Precision Test SM & New Physics) The Report on Our Work Plan? ( ) Sub-groups? etc July 13-17, 2011 Modenized Z-Factory 3

4 Physics Topics Theoretical investigation (for physics goals of Z-factory) (The theoretical investigation might influence ILC final decision) A. Z boson properties: (Precision Test SM & New Physics) LEP-I: Scan 88GeV~94GeV hadronic events; leptonic events Detectors: Aleph, Delphi, L3, Opal. SLC: At Z-peak events (Especially electron polarization beam: 70%) Detector: SLD Very precision and rich results for Z-boson properties were achieved and indicated the predictions of SM work well: July 13-17, 2011 Modenized Z-Factory 4

5 A. The properties of Z-boson Measurements vs SM prediction: SM works well! If Z-factory may improve the results substantially, the systematical errors must be suppressed & to understand the precision results, two-loop theoretical cals. of SM (self-energy & vertices) are needed Constraints for new physics! July 13-17, 2011 Modenized Z-Factory 5

6 A. The Z effective coupling (to lepton) New Physics: (W.G. Ma et al, Z.-X. Yue et al, K.M. Yang et al, X.-Q. Li et al, Z Z L. Han et al, J.-J. Cao et al etc) Multi-Higgs Model, Little Higgs Model, RPV SUSY Model, Extra Z- boson Model etc The effective coupling Z-ff (tree and loops & specially f,f are leptons) : effective vertex specially the couples to lepton sector ff is a very strong constraint to the models, and Z- factory will offer the precise measurements of it. New physics through tree and/or loop diagrams July 13-17, 2011 Modenized Z-Factory 6

7 A.The neutral flavor change vertex The coupling ZAAA (A: a CP odd light Higgs): A strongly couples to leptons (especially to pair) and the decay of Z to A are very strong constraints to such models. etc Some special models are very sensitive to the coupling of Z- boson to τ-lepton and relevant decays, thus Z-factory is crucial for this kind of models. The Models: Lepton number violation Baryon number violation Cosmology baryon number generation. July 13-17, 2011 Modenized Z-Factory 7

8 A.The neutral flavor change vertex Very important work for high precision tests: Two loop corrections for SM: (focus on lepton sector more) Self-energy corrections, Vertex corrections, etc Shell we discuss (focus on) the difficulties and accessibility for precision physics in the meeting? July 13-17, 2011 Modenized Z-Factory 8

9 B. c & b-hadron physics (QCD) c & b-quark fragmentation: (Z.-G. Si, et al) Non-perturbative fragmentation models: LUND, Webber Cluster, Quark Combination (ShangDong) Model. The best place to test the model. Fragmentation functions (FFs) from c or b quark: Very important for flavor-tagging! July 13-17, 2011 Modenized Z-Factory 9

10 B. c & b-hadron physics (QCD) Confirm B-factory results for flavor c: Ds meson: to confirm the excited states etc, c-baryons (Λ c, Ξ c, Ω c, etc): production mechanism(s), to confirm the decays, excited states etc, Double heavy baryons (Ξ cc, Ω cc, Ξ bc,,ω bc etc): production mechanism(s), decays, excited states etc, To confirm the ISR production of X, Y, Z particles: production mechanism(s), properties etc. July 13-17, 2011 Modenized Z-Factory 10

11 B. c & b-hadron physics b-hadron excited states (beyond B-factory): B c meson and baryons Λ b, Ξ b, Ω b,, Ξ bc, Ξ bb, etc and their excited states, can be expected to observe at Z-factory, although it is difficult. Heavy quarkonium physics: a. Puzzle or not? for Υ(η b ) production mechanism b. Υ(η b ) excited states (even hybrids) c. Exotics X b, Y b, Z b via ISR similar to B-Factory d. Hybrid states? maybe the heavy quark hybrid states are easier identified than light quark ones. etc b-rare decays: July 13-17, 2011 Modenized Z-Factory 11

12 B. c & b-hadron physics (QCD) c-hadron studies (competitions from B- factories, Tevatron, LHCb etc) : 0 0 D-meson: D D mixing (New) Due the Lorentz boost and the lifetime of D meson at Z-factory the CP violation in the mixing can be observed, whereas it is impossible at B-factory & τ- Charm factory. (H.-B. Li & M.-Z. Yang) To confirm and/or discovery the excited charmed states (mesons and baryons) etc July 13-17, 2011 Modenized Z-Factory 12

13 B. c & b-hadron physics (QCD) b-hadron studies (competitions from LHCb) B-meson: excited states etc, Bs meson: mixing, CP violation, rare decays, excited states etc, Bc meson: production mechanism(s), decays, excited states etc, b-baryons (Λ b, Ξ b, Ω b, etc): production mechanism(s), decays, excited states etc, Double heavy baryons (Ξ bc, Ξ bb, etc): production mechanism(s), decays, excited states etc, bb ISR production of -like X, Y, Z particles: production mechanism(s), properties etc The heavy quark hybrid states are easier identified than light quark ones. July 13-17, 2011 Modenized Z-Factory 13

14 B. c & b-hadron physics & mass spectra : (G.L. Wang et al; X.Q. Li et al) The D-wave dominant 1 -- states of have not observed yet! July 13-17, 2011 Modenized Z-Factory 14

15 B. c & b-hadron physics (QCD) Production mechanisms for double heavy hadrons: (C.H. Chang, X.G. Wu et al) At LEP-I: Bc meson just a few (J/Ѱ+π) events, thus at Z-factory a few thousands of such events! Many decay modes can be observed, and excited states may be seen too. The cross-sections for heavy quarkonia and excited states are similar to that of Bc meson but they are easy to observe. The cross-section of double heavy baryon production is the same in magnitude, thus the situation is similar to Bc meson. July 13-17, 2011 Modenized Z-Factory 15

16 B. c & b-hadron physics -like X, Y, Z particles (ISR): The cross-section is smaller than that of X off Z-peak, because charge Q b = -1/2 Q c! Structures July 13-17, 2011 Modenized Z-Factory 16

17 B. c & b-hadron physics (QCD) Production of heavy quarkonia and X -type particles via two-body exclusive production with a photon: July 13-17, 2011 Modenized Z-Factory 17

18 B. c & b-hadron physics (QCD) July 13-17, 2011 Modenized Z-Factory 18

19 B. c & b-hadron physics (QCD) July 13-17, 2011 Modenized Z-Factory 19

20 B. c & b-hadron physics (QCD) In SM Z-boson is a gauge boson for weak interaction & couples to all quarks and leptons directly. The effects of resonance at Z-factory for all flavors of quarks and leptons Focus on heavy flavors c, b and relevant hadrons! Shell we focus on the heavy flavor (b) physics in the meeting? July 13-17, 2011 Modenized Z-Factory 20

21 C.τ-lepton physics Very good source ofτ-lepton Z-factory): Based on SM: m Z, Sin 2 θ W, α,γ Z, etc Z-peak ~ 0.5 the highest one ~ 2.3 B-factory The most important thing is the Lorentz boost effects: July 13-17, 2011 Modenized Z-Factory 21

22 C.τ-lepton physics The most important is the Lorentz boost effects: Lifetime : τ= s (comparatively small), cτ μm Lorentz Z-factory: γ Z-fac = 25.66, cτ γ μm B + -meson: τ= s cτ μm B 0 -meson: τ= s cτ μm B s -meson: τ= s cτ 441 μm D + -meson: τ= s cτ μm D 0 -meson: τ= s cτ μm D s -meson: τ= s cτ μm With vertex detector the momentum-energy of the produced τ-lepton is well measured, but the vertex detector works well for the τ-lepton only when γ is comparative Z-factory, γ is quite great indeed. July 13-17, 2011 Modenized Z-Factory 22

23 C.τ-lepton physics Very good source of τ lepton Production at a much high energy (much higher than threshold) thus cause greater boost effects than B-factory (good for vertex detector) Rare decays for τ-lepton (sensitive to new physics): e,,, ee, eee, the models: baryon genesis via lepton number violation! etc, crucial for the upper bound for τ lepton rare decays will be suppressed much Polarized beam of e - e + and CP violation relating to τ lepton 电子束极化的条件下 ( 如 SLC 上的实验 ), 末态轻子对左右前后不对称大小为 0, 3 ( FB) L( FB) R 1 ALRFB Pe A 4 ( F B) L( FB) R Pe Various CP-odd observables: July 13-17, 2011 Modenized Z-Factory 23

24 C. CP violation in leptonic sector Via measuring the CP(T)-odd observables: in the process with un-polarized beam and the CP odd observables: in the process with polarized beam To find CP violation purely in the leptonic sector and precisely to set stringent bounds on CP violation. All of the above CP-odd observables contain the momentum of the produced τ-lepton, is crucial! July 13-17, 2011 Modenized Z-Factory 24

25 C. CP violation in leptonic sector LEP-I example: CPV of V Zττ : (weak dipole) If we define: The limit means: Statistics errors quite large, so there are rooms to improve the measurement(s)! July 13-17, 2011 Modenized Z-Factory 25

26 C. CP violation in leptonic sector Effective L: T. Huang, J.-M. Yang et al, PRD 58, (1998) July 13-17, 2011 Modenized Z-Factory 26

27 C.τ-lepton physics 比较无极化极化束条件 ( 如 LEP 上的实验 ) 0, 3 F B AFB Ae A 4 F B 极化束的优点在于, 可以在统计精度上使测量值优于非极化束条件下的测量, 例如,75% 电子极化可给出相当与非极化束条件下的 25 倍统计量的精度 Polarized e - and/or e + beam produces τ + τ - pair: CP violation: to measure CP(T)-odd operators precisely To measure the CP violation in τ decays beyond SM: (numerous events with great boost) July 13-17, 2011 Modenized Z-Factory 27

28 C.τ-lepton physics Pure leptonic and hadronic decays (test of universality sensitive to QCD and light hadron physics etc): 弱作用低能有效理论 e,, W d d s cosc sinc e,, d u hadron() s l To determine the quantum numbers of the excited states (vector and axial vector currents respectively) July 13-17, 2011 Modenized Z-Factory 28

29 τ -lepton physics 例如 : 在 KK 末态的 V 与 A 贡献 (I1) 2 4 s ee KK ( KK) Aleph & CLEO: A: (7525)% etc July 13-17, 2011 Modenized Z-Factory 29

30 C.τ-lepton physics Shell we focus on the τ-lepton physics (CPV) in the meeting? July 13-17, 2011 Modenized Z-Factory 30

31 D. What topic(s) else More topics, if they are interesting enough! Let us think about. July 13-17, 2011 Modenized Z-Factory 31

32 E. Plan for next To make the working plan for next Sub-group? Link persons? etc July 13-17, 2011 Modenized Z-Factory 32

33 Thanks! July 13-17, 2011 Modenized Z-Factory 33