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Exploring New Physics with Belle II: A Comprehensive Overview of Methods and Processes

This paper provides an in-depth examination of how the Belle II experiment can offer crucial insights into new physics phenomena, complementing other experiments. It covers various processes such as (semi)inclusive B meson decays and neutrals, showcasing the experiment's potential impact on flavor physics. Detailed physics programs and methodologies are discussed, highlighting the experiment's significance in the context of the B Factories. The document also references key papers exploring Belle II's contributions to flavor physics studies.

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Exploring New Physics with Belle II: A Comprehensive Overview of Methods and Processes

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  1. CPV & LFV/LFU @ Belle II BoštjanGolob University of Ljubljana/Jožef StefanInstitute & Belle/Belle II Collaboration Introduction (Examples of...) LFU LFV CPV Summary University of Ljubljana “Jožef Stefan” Institute Heavy Flavor 2016 Quo Vadis?

  2. Introduction “SuperKEKB”Accelerator e- (HER): 7.0 GeV e+ (LER): 4.0GeV ECMS=M(U(4S))c2 dNf/dt =s(e+e-→f) L L =8x1035 cm-2 s-1 B → fKs Lumi ratio for same sensitivity B → J/yKs B → tn Belle 2 Belle Ee+beam 5 ab-1 20 ab-1 Phase 1: w/o QCS, Belle 2 Phase 2: w/ QCS, Belle 2 (no VXD) Phase 3: full Belle 2 2016 2017 2018 2019 2020 2021 Phase 3 Phase 1 Phase 2 QCS, Belle 2 VXD 35 ab-1 50 ab-1 2022 2023 2024 2025 2026 2027 2028

  3. Subjects Methods and processes where Belle 2 can provide important insight into NP complementary to other experiments: Emiss: B(B→tn), B(B → Xctn), B(B → hnn),... (Semi)Inclusive: B(B → sg), ACP(B → sg), B(B → sll ), ... Neutrals: S(B → KSp0g), S(B → h’ KS), S(B → KSKSKS), B(t→ mg), B(Bs→ gg), ... Detailed description of physics program at Belle 2 in: The Physics of the B Factories B.G.,, K, Trabelsi, P. Urquijo, BE LLE2-NOTE- PH-2015-002 A.G. Akeroyd et al., arXiv: 1002.5012 Impact of Belle II on Flavor Physics P. Urquijo, BE LLE2-NOTE- PH-2015-002 Ed. A.J. Bevan, B. Golob, Th. Mannel, S. Prell, and B.D. Yabsley, Eur. Phys. J. C74 (2014) 3026 Belle I I - LHCb measurement extrapolation comparisons B. O’Leary et al., arXiv: 1008.1541

  4. LFU/Missing energy Btn, hnn, Xctn,... possible to reconstruct events with n‘s; fully (partially) reconstruct Btag; reconstruct h± from Bsig; no additional energy in EM calorim.; signal at EECL~0; Partial reconstruction (semileptonic tagging): etag~1% Missing E (n) Btag Bsig Bsig → tn candidate event D*± Bsig l Btag n

  5. LFU/Missing energy B D*tn R(D(*)) R(D)SM=0.300 ±0.008 R(D*)SM =0.252 ±0.003 use NN with M2miss, Evis, cosqB-D* lsig. data sample with low M2miss used to fit the background contribution l=e,m Belle, arXiv:1603.06711, 700fb-1 H. Na et al., Phys.Rev.D 92, 054410 (2015) S.Fajfer et al., Phys.Rev.D85(2012) 094025 NN output for data with M2miss > 0.85 GeV2 signal is to the right →

  6. LFU/Missing energy B D*tn R(D*)=0.302±0.030±0.011 Belle, arXiv:1603.06711, 700fb-1 s(R(D*))/R(D(*))[%] HFAG, http://www.slac.stanford.edu/xorg/hfag/ 4s discrepancy with SM 3.5 s from SM @ 5 ab-1 5 sfrom SM @ 20 ab-1 L[ab-1]

  7. LFU/Missing energy Dsln inclusive D meson reconstr. cc→ Dtag Ds* (→ Dsg) Kfrag Xfrag Mmiss(Dtag gKfragXfrag) = MDs Ds→mn Mmiss(Dtag gKfragXfrag m) = Mn inclusive reconstruction of Ds Belle, JHEP09, 139 (2013), 900fb-1 reconstruction of Dsmn

  8. LFU/Missing energy Dsln Ds→tn EECL Belle, JHEP09, 139 (2013), 900fb-1

  9. LFU/Missing energy s(X)/X[%] Dsln B.G.,, K, Trabelsi, P. Urquijo, BE LLE2-NOTE- PH-2015-002 RDst/m Br(Ds→mn) Br(Ds→tn) RDst/m= Br(Ds→tn) / Br(Ds→mn) RDst/m=10.73 ± 0.69 ± 0.55 (RDst/m)SM= 9.762 ± 0.031 Belle, JHEP09, 139 (2013), 900fb-1 L[ab-1] n.b.: s(R(D*))/R(D(*)) ~4% @20 ab-1

  10. LFU/B →K*l l B K*l l angular analysis BK*mm BK*ee Nsig=118±12 Nsig=69±12 Belle, arXiv:1604.04042, 700fb-1 P5‘ LHCb, JHEP 1308 (2013) 131

  11. LFU/B →K*l l B K*l l R(K*)= N(BK*ee) N(BK*mm) approximate stat. uncertainty on R(K*) Belle, arXiv:1604.04042, 700fb-1 L[ab-1] 0.7 5.0 20.0

  12. LFV/t → m g e g t → m g g m m t t Belle, PLB66, 16 (2008), 535 fb-1 e e e e kinematic variables for signal isolation: DE=ECM(mg)-ECM(beam) Minv=m(mg) main background from ee→ t(mnn) t(pn)gISR BrUL 1/ √L t t p p n n signal n n expected sig. B5x10-7 background e

  13. LFV/t → m g simplified (1D) toy MC UL90% B(t → m g) [10-8] 4 2 1 0.4 0.2 t → m g  1/L Belle, PLB66, 16 (2008), 535 fb-1 B(t→ m g) < 4.4 ·10-8 decays t→ 3l, l h0background free  1/√L 0.2 1 10 L[ab-1] B.G.,, K, Trabelsi, P. Urquijo, BE LLE2-NOTE- PH-2015-002

  14. CPV/B→ sqq b → sqq t-dependent CPV - some uncertainties cancel in DS (vtx reconstr., flavor tag, likelihood fit) ; - better KS eff. with vtx hits - larger vtx radius, 30%); - vtxreconstr. improved with better tracking; 41 new phases in MSSM DS=sin2f1eff -sin2f1 s(sin2f1(J/yKs)) s(s) 3Ks 0.007 fKs P. Urquijo, Belle2-note-ph-2015-004 0.045 h‘Ks s(sin2f1(fKs)) 0.020 J/yKs 0.02 B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002

  15. CPV/B→ sg t-dependent decays rate of B → fCP; S and A: CP violating parameters B → K* (→KSp0)g t-dependent CPV SM: SCPK*g -(2ms/mb)sin2f1  -0.04 Left-Right Symmetric Models: SCPK*g 0.67 cos2f1  0.5 SCP(Ksp0g) = -0.10 ±0.31 ±0.07 ACP(Ksp0g) = -0.20 ±0.20 ±0.06 for m(Ksp0) < 1.8 GeV (mainly K*g) D. Atwood et al., PRL79, 185 (1997) B. Grinstein et al., PRD71, 011504 (2005) Belle, PRD74, 111104 (2006), 500 ab-1

  16. CPV/B→ sg B → K* (→KSp0)g t-dependent CPV SCPKsp0g= -0.15 ±0.20 ACPKsp0g= -0.07 ±0.12 HFAG Summer 2012 HFAG, Summer’12 5 ab-1 s(SCPKsp0g)= 0.11 @ 5 ab-1 0.04 @ 50 ab-1 (~SM prediction) 50 ab-1 B.G.,, K, Trabelsi, P. Urquijo, BE LLE2-NOTE- PH-2015-002 for B→r0g ~2x larger uncertainty

  17. DCPV/B→ sg B → s(+d)g direct CPV Semi-inclusive, sum of many exclusive states:all flavor specific final states; <D>: average dilution due to flavour mistag, 1 DD: difference between flavour mistag for b and b, << 1 Adet: detector induced asymmetry BaBar, PRL101, 171804(2008),350 fb-1 b → sg b → sg Adet: careful study of K/pasymmetries in (p,qlab) using D decays or inclusive tracks from fragmentation; lots of work on system.,  few 10-3exp. sensitivity

  18. DCPV/B→ sg B → sg direct CPV Inclusive, g recontruction only; bkg. suppression (kinematic event shape variables); semileptonic tagging; Similar sensitivity expected for semi-inclusive & fully inclusive Belle, PRL114, 151601 (2015), 700 fb-1 HFAG, 2014(?) SM: ACP ~ (0.0044±0.00240.0014)% T. Hurth et al., Nucl.Phys. B704, 56 (2005) sum of excl. incl. 5x10-3

  19. Summary LFU: important measurements to be performed already with 5 – 10 ab-1 (2019-2020) LFV: 50 ab-1 (2023) needed to reduce existing limits by > 10 CPV: in rare modes 20-50 ab-1 (2021-2023) needed to reach SM expectations

  20. Summary

  21. Summary

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