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Belle II Physics Program

Belle II Physics Program. Boštjan Golob University of Ljubljana/Jozef Stefan Institute & Belle/Belle II Collaboration. General (plan, specifics, subjects) Examples of measurements ( E miss , neutrals, inclusive) Summary. University of Ljubljana. “Jožef Stefan” Institute.

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Belle II Physics Program

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  1. Belle II Physics Program Boštjan Golob University of Ljubljana/Jozef Stefan Institute & Belle/Belle II Collaboration General (plan, specifics, subjects) Examples of measurements (Emiss, neutrals, inclusive) Summary University of Ljubljana “Jožef Stefan” Institute Strategic Workshop in Switzerland SWICH 2018

  2. Introduction Triple approach (... To contepmporary high energy physics) Energy Frontier origin of mass hierar- chies dark matter NP matter/ antimatter dark energy n‘s Intensity Frontier Cosmic Frontier

  3. Plan Super KEKB luminosity planning 3 - 6 ab-1 0.8 -1.5ab-1 7 - 13 ab-1 Phase 1 Phase 2 Phase 3 → Phase 1: w/o QCS w/o Belle 2 Phase 2: w/ QCS w/ Belle 2 (no VXD) Phase 3: full Belle 2 QCS, Belle 2 VXD 12 - 24ab-1 20 - 38 ab-1 http://lhc-commissioning.web.cern.ch/lhc-commissioning/schedule/LHC%20schedule%20beyond%20LS1%20MTP%202015_Freddy_June2015.pdf according to Medium Term Plan for 2016-2020, https://cds.cern.ch/record/2053977/files/MTP%202015_FC%205932.pdf

  4. Specifics • Properties of e+e-Colliders • (as compared to LHC) • low energy e- g g D. Curtin et al., arXiv:1412.0018 e e: g(Z0)A‘ coupling e+ A‘ c c A. Bondar et al., Belle2-note-ph-2015-003; l + B2TiP report Z0 h l - e A‘ l + Z0 l - 10-1 1 10 100

  5. Specifics • Properties of e+e-Colliders • (as compared to LHC) • low energy • low trigger rate / Event size (30 kHz 1st level, 10 kHz high level; • 300 kB event size) • low multiplicity (O(10)) • good hermiticity • specific methods for full event interpretation (FEI) fully (partially) reconstruct Btag; → Bsig 4-momentum known reconstruct h from e.g. Bsig→ t(→ hn)n; no additional energy in EM calorim.; signal at EECL~0; reconstruction of B mesons with invisible particles in final state; FEI performed using MVA, ehad ~ 1%, Phad~65% esl~ 3%, Psl~30% Missing E (n) Btag Bsig Bsig→t n (→ l n) candidate event

  6. Subjects Methods and processes where Belle 2 can provide important insight into NP complementary to other experiments: Emiss: B→tn, B →Xctn, B →hnn, B → Xu l n, Ds →tn, A‘→ cc,... (Semi)Inclusive: B → sll, B → sg, B → dg, ... Neutrals: B → KSp0g, B → h’ KS, B → KSKSKS, t→ mg, D0 → h0h0, D0 → Vg, Bs→ gg, ... N.B.: at the intensity frontier both, exp. and th. accuracy must ~match in order to be able to spot deviations from SM; Subjects can be re-ordered into physics topics: Belle II PhysicsGroups Semil. & EmissDecays Rad. & EW Penguins t-dependent CPV Hadronicb→c Hadronicb→non-c bb cc CharmLowmult. & darksector

  7. Subjects Methods and processes where Belle 2 can provide important insight into NP complementary to other experiments: Semil. & EmissDecays: inc. & excl. leptonicb → c, b → u transitions; leptonicB decays; EW penguindecayswithn‘ s; lepton flavor universality & lepton numberviolations B→tn, B →Xctn, B → Xu tn,B→tn, B →hnn,… Rad. & EW Penguins: B mesondecaysinvolving FCNC B → sll, B → sg, B → dg, Bs→ gg, ... t-dependent CPV: 1,(b), 2 (a) B → J/yKS, B → h’ KS, B → KSKSKS, ... Hadronicb→c: direct CPV, 3 (g) B → DK, B → Dhh‘, B → Dsp, ... Hadronicb→non-c: charmlesshadronic B decays & DCPV B → K0p0, B →p+p0p0, B → p0p0, Bs→ KsKs,… bb: U(nS) cc: charmonium(like) states Y(4260), X(3872), U(nS) → XYZ Charm: open charm, decays, oscillations & CPV Ds→tn, D0 → h0h0, D0 → Vg, ... Lowmult. & darksector: t, darkmattersearches, gg t→ mg,A‘→ cc,...

  8. Subjects Methods and processes where Belle 2 can provide important insight into NP complementary to other experiments: Detailed description of physics program at Belle 2 in: Physics of B Factories A.G. Akeroyd et al., arXiv: 1002.5012 B. O’Leary et al., arXiv: 1008.1541 Ed. A.J. Bevan, B. Golob, Th. Mannel, S. Prell, and B.D. Yabsley, Eur. Phys. J. C74 (2014) 3026 Belle I I Theory Interface Platfrom (B2TiP) E. Kou, P. Urquijo eds., to be published in Prog. Theor. Exp. Phys. New!

  9. Missing energy B D*tn R(D(*))= B(B D*tn) / B(B D* ln) R(D)SM= 0.300 ±0.008 R(D*)SM = 0.252 ±0.003 semil. tag; use NN with M2miss , Eecl, cosqB-D* lsig. data sample with low Onbused to fit the background contribution Belle, PRD 94, 072007, 700 fb-1 l=e,m Test of Lepton Flavor Universality (LFU) H. Na et al., Phys.Rev.D 92, 054410 (2015) signal → S.Fajfer et al., Phys.Rev.D85(2012) 094025 23123 D* tn 280057 D* ln Eeclfor data with Onb > 0.8

  10. Missing energy B D*tn R(D*)=0.302±0.030±0.011 Belle, PRD 94, 072007, 700 fb-1 current WA Belle II 5 ab-1 Belle II 50 ab-1 s(R(D(*)))/R(D(*))[%] SM 3.7 s @ 5 ab-1 (~2020) 6.3 s @ 20 ab-1 (~2022) R(D) R(D*) combination of tagging methods (R(D*): had., semil., untagged R(D): had.) L[ab-1] B2TiP Report

  11. Neutrals CPV in b → sqq some uncertainties cancel in DS (vtxreconstr., 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(sin2f1eff) B2TiP Report  P. Urquijo, Belle2-note-ph-2015-004 w(p+p-p0)Ks f(K+K-)Ks  h‘(gg)Ks  0.007 L[ab-1]  th. uncertainty s(sin2f1) fromB → J/yKs M. Beneke, PLB620,143 (2005)

  12. Inclusive b → Xs l +l - inclusive mode: complementary to B  Xsg ; lower hadronic uncertainties compared to exclusive; complement to meas.‘s of exclusive decays; main bkg‘s: cc semil. decays BB  semil. B/D decays B  j/y (Y(2S) Xs with larger statistics fully inclusive study possible (as for B  Xsg); Estimates for sum of exclusive modes, M(Xs)<2GeV (can be relaxed); can be rejected by Emiss can be rejected by M(l +l -) s(X)/X B2TiP Report Belle, PRL103, 241801, (2008), 605 fb-1 Dependingon q^2 Bin (3 bins) s(B)/B ~ 7% continuum p0 gg h gg b  sg B AFB s(Afb)/Afb ~ 5% L[ab-1]

  13. Inclusive b → Xs l +l - B and diff. decay distrib. (e.g. in q2 & cosq) depending on Wilson coeff.‘s (C7,9,10) q2=M2(l +l -) l + q B Xs B2TiP Report l - costraints on C9,10NP from Belle II measurements of B and AFB @ 50 ab-1 SM: (0,0) n : n s contour : fit to current exclusive observables 6 s 4 s

  14. Summary LHCb „domain“ Belle II „domain“ • complementarity! • not only for „political“ reasons, • needed for systematic checks of • NP signals and identification of • their nature B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002

  15. Summary scalar leptoquarks I. Dorsner et al., J. High Energ. Phys.2017: 188 intensity + energy frontier intensity frontier model param. 1 model param. 1 R(D(*)) Rem(D(*)) dilepton spectrum b smm model param. 2 model param. 2

  16. Summary LHCb „domain“ Belle II „domain“ • complementarity! • not only for „political“ reasons, • needed for systematic checks of • NP signals and identification of • their nature • Intensity frontier exp‘s able to reach • NP mass scales beyond the reach of • LHC B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002

  17. Summary MZ‘=15 TeV ! LH/RH A.J. Burasz et al., JHEP 1411, 121 (2014) B(B  K*nn) BSM(B  K*nn) B(B  K*nn) BSM(B  K*nn) Z‘ with L(R, L+R) couplings satisfying DF=2 constraints; effect on DF=1 processes RH LH B(B  Knn) BSM(B  Knn) B(B  Knn) BSM(B  Knn) MZ‘=50 ! TeV MZ‘=80 TeV ! LH/RH LH+RH B(KL p0nn) [10-11] LH < RH LH > RH B(K+ p+nn) [10-11]

  18. Summary LHCb „domain“ Belle II „domain“ • complementarity! • not only for „political“ reasons, • needed for systematic checks of • NP signals and identification of • their nature • Intensity frontier exp‘s able to reach • NP mass scales beyond the reach of • LHC • Belle ii will in 2019 – ~2025 perform • rich program of (very) rare • processes (very) sensitive to NP • eagerly expecting • high luminosity • datataking with • Belle II B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002

  19. Additional material

  20. Energy/Intensity frontier LHCb,LHCb-PAPER-2017-017 23123 D* tn b p(r)tn (~10%) bcJ/ytn (~10%) Lb Lctn (~5%) : Belle, PRD 92, 072014 (2015) 700 fb-1 „hope for“ accuracy in 2023 Intensity Frontier deviation from SM; systematic tests in related processes 127395 D* tn R(D(*)) I. Dorsner et al., J. High Energ. Phys.2017: 188 Models Models Rem(D(*)) model param. 1 dilepton spectrum model param. 2 b smm scalar leptoquarks Energy Frontier Search for direct production of related particles Atlas, DOI: 10.1007/JHEP10(2017)182

  21. SuperKEKB Accelerator “SuperKEKB” SuperKEKB: e- (HER): 7.0 GeV e+ (LER): 4.0GeV ECMS=M(U(4S))c2 (→BB) [M(U(1S))c2,M(U(6S))c2] dNf/dt =s(e+e-→f)L L =8x1035 cm-2 s-1 Tokyo (40 mins by Tsukuba Exps) LER e- HER Belle 2 e+

  22. Specifics • Propertiesofe+e-Colliders • (as compared to LHC) • lowenergy • low trigger rate / Event size • (30 kHz 1st level, 10 kHz high level; 300 kB event size) • low multiplicity (O(10))

  23. Semil. tagging Btn, hnn, Xctn,... Full reconstruction (hadronic tagging) or partial reconstruction (semileptonic tagging): Missing E (n) Btag Bsig Bsig → tn candidate event D*± Bsig l± Btag n

  24. Boost B → fKs Lumi ratio for same sensitivity B → J/yKs P. Urquijo, Belle2-note-ph-2015-004 B → tn Belle 2 Belle Ee+beam Ee-beamfrom U(4S) mass B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002 Belle 2: improved KS reconstr.; improved hadr. B tagging; LHCb: ss; run 2 50% less eff. for hadronic triggers than run 1; run 3 increase eff. for hadr. triggers by 2x w.r.t. run 1; Belle II B-tagged LHCb Hadronic Relative yield increase LHCb EPJC 73, 2373

  25. Beastphase1 Measurements of beam bkg‘s in Phase 1 P.M. Lewis et al., arXiv:1802.01366 spectrum of fast neutrons separation of Touschek and BeamGas (bremssthralung+Coulomb scattering) contrib. P: pressure Ze2: effective atomic number of gas sy: vertical beam dimension Obs.: bkg sensitive observable in Beast detector

  26. Phase 2 Status: Phase 2 (full Belle II w/o SVD) started March 19, ongoing until July; both beams successfully stored, collisions expected in ~ week Arich cherenkov ring cosmic ray (1/8 of) VXD CDC hits SVD hits cosmic ray top modules

  27. phase 2 Phase 2 (full Belle II w/o SVD) started March 19 24h SuperKEKB history both beams successfully stored, no collisions yet e- beam current

  28. phase 2 Beam squeezing L(phase 2) ≤ 4 1034 cm-2s-1 L(peak KEKB) ~ 2 1034cm-2s-1

  29. BD*tn M.Tanaka, R.Watanabe Phys. Rev. D87 (2013), 034028 Polarization in BD*tn SM+tensor SM+vector SM+scalar SM qhel M Using had. tag & 2-body hadronic tdecays JM=0, a=1 JM=1 (M=r a=0.45) W nt t nt Belle, arXiv:1608.06391 Belle II, 50 ab-1 B2TiP report diff. distr.‘s also differentiate between SM and NP: expected data @ 50 ab-1, SM Also D* polarization can be measured and can differentiate among NP models 2HDM type II, tanb/mH±=0.5(GeV/c2)-1

  30. LFU charm 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*) ~2.5% @ 20 ab-1

  31. Bhnn Belle preliminary, arXiv:1303.3719, 711 fb-1 Bhnn B(B+ K(*)nn) can be measured to ±10% with 50 ab-1; similaraccuracyfor B+ K*0nn, B+ K*+nn, B+ K+nn; combinedsemil. + had. tag; limits on right-handed currents -- signal -- background K*nn Knn FL SM approx. expected precision @ 50 ab-1 B2TiP report W. Altmannshofer et al., arXiv:0902.0160

  32. B+ tn B+ tn projected accuracy on B(B+→t+n) Belle, PRL110, 131801 (2013), 700fb-1 Nsig=62 ± 24 s(B)/B hadronic tag had. tag Nsig=222 ± 50 semil. tag L[ab-1] corresponding |Vub| uncertainty (experimental): semil. tag, 50 ab-1: ~3% hadr. tag, 50 ab-1: ~3% semil. tag Belle,arXiv:1503.05613, 700fb-1

  33. b → Xs l +l - b → Xs l +l - diff. distribution q2=M2(l +l -) z=cosq s=q2/mb2 l + q B Xs l - K.S.M. Lee et al., Phys. Rev., D75, 034016 (2007); A. Ali et al., Phys. Lett., B273, 505 (1991)

  34. b → K*l +l - b → K*l +l - P5‘ accuracy q2=M2(l +l -) s(P5‘ ) B2TiP report LHCb, JHEP 02 (2016) 104, 3 fb-1 l=e+m q2 [GeV2] 1.0-2.5 2.5-4.0 4.0-6.0 >14.2 L[ab-1]

  35. b → K(*)l +l - b → K(*)l +l - R(K), R(K*) accuracy s(x)/x B2TiP report R(K*) [1GeV2,6 GeV2] LHCb, arXiv:1705.05802, 3 fb-1 R(K) [1GeV2,6 GeV2] LHCb, Phys. Rev. Lett., 113, 151601 (2014), 3 fb-1 q2 [GeV2] 1.0-6.0 >14.4 R(K) R(K*) L[ab-1]

  36. b → stt b → stt probably not observed even with full stat.; Br(B→ K*tt) < 210-5 @ 50 ab-1 BrSM(B→ K*tt)~ 110-7 compared to K*nn(with additional two tracks from t) - using had. tagging only (too many n‘s in semil. tag) N(K*tt)/N(K*nn) ~ (ehad/(ehad+esl)) [Br(B→ K*tt) / Br (B→ K*nn)] Br(t) ~ ½ 10-2 0.1 ~ 5  10-4 + some bkg from B → Xc(→ Xsln)ln B2TiP report

  37. B  s(+d) g B s(+d) g experimental challenge: huge bkg; only greconstructed in the signal side g Bsig Xs Btag l±1.26 GeV < E < 2.20 GeV Belle, PRL103, 241801, (2008), 605 fb-1 K : different method: hadronic tagging (= full reconstruction of Btag); reduction of system.uncertainty on the account of lower efficiency (ehad ~ 1%); g Bsig continuum p0 gg h gg b  sg Xs p Btag p B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002 similar accuracy with sem. tag 5%

  38. B → sg • B → sg • 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 Adet: careful study of K/pasymmetries in (p,qlab) using D decays or inclusive tracks from fragmentation; lots of work on system.,  few 10-3 exp. sensitivity semi-inclusive method most accurate (uncertainty stat. dominated) b → sg b → sg HFAG, 2014 SM: ACP ~ (0.44±0.240.14)% T. Hurth et al., Nucl.Phys. B704, 56 (2005) 3x10-3 B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002

  39. b  d g b  d g within SM: Br(B → dg) / Br(B → sg) =(3.8 ±0.5) 10-2 (ratio can be used to determine |Vtd/Vts|) Br(B→sg) = 3.410-4 Br(B →dg) should be measured with an accuracy of ~(0.5 10-2) (3.410-4) ~210-6 sum of exclusive modes: s(Br(dg)) = (±3±1)10-7 low Xd mass region s(Br(dg)) = (±20±22)10-7 high Xd mass region T. Hurth et al., Nucl.Phys. B704, 56 (2005) BaBar, PRD82, 051101 (2010), 0.4ab-1 largest syst. uncertainty: B → s gbkg.; missing (>= 5 body) modes; significant improvement necessary Belle 2 full simulation: 15% B0K*(Kp)g, B0r(pp)g B. Golob, K. Trabelsi, P. Urquijo, Belle2-note-ph-2015-002

  40. DCPV puzzle B0 →K+p- • DCPV puzzle: • tree+penguin processes, B+(0)→K+p0(-) • DAKp= A(K+p-)- A(K+p0)= -0.147±0.028 Belle, Nature 452, 332 (2008), 480 fb-1 IKp B (B0→ K+p -) Mbc s(ACP(KSp+)) M. Gronau, PLB627, 82 (2005); D. Atwood, A. Soni, PRD58, 036005 (1998) s(ACP(K-p+)) Belle K0p0 Belle II K0p0 50 ab-1 P. Urquijo, Belle2-note-ph-2015-004 B2TiP report

  41. LFV e g Search for 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 polarized beam(s) would help t t p p n n signal n n expected sig. B5x10-7 background e

  42. LFV simplified (1D) toy MC UL90% B(t → m g) [10-8] 4 2 1 0.4 0.2 Search for t → m g  1/L w/o polarization: UL90%(B(t → m g))  2x10-9@ 50 ab-1 w/polarization: factor ~(2-3)x better sensitivity decays t→ 3l, l h0 background free UL90%(B(t → m g))   1/ L to ~10ab-1 B(t → m g)<4.4 ·10-8 Updated expected sensitivities  1/√L 0.2 1 10 L[ab-1] t → m g t → mmm Belle, PLB666, 16 (2008), 535 fb-1 K. Inami, PANIC 2011

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