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Searching for New Physics in CP-violation measurements at LHCb

Searching for New Physics in CP-violation measurements at LHCb. Steven Blusk Syracuse University (on behalf of the LHCb Collaboration). 701 members 15 countries 52 institutes. Other LHCb talks at DPF09 LHC b Detector Status………………..… E. Jans……27-July

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Searching for New Physics in CP-violation measurements at LHCb

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  1. Searching for New Physics in CP-violation measurements at LHCb Steven Blusk Syracuse University (on behalf of the LHCb Collaboration) • 701 members • 15 countries • 52 institutes Other LHCb talks at DPF09 LHCb Detector Status………………..… E. Jans……27-July Early Physics with LHCb…………..…F. Dettori……27-July LHCb Prospects for rare Decays…..M-O. Bettler……30-July DPF2009, July 26-31, 2009, Wayne State University

  2. Outline • Introduction • The LHCb Experiment • sin(2bs) in Bs mixing • Measurements of g • Conclusions • Not covering measurements of a, sin(2b) or D0 mixing/CPV, although these are also part of the LHCb core program. • Rare decays covered in talk by M-O. Bettler @ 17:10 in “Beyond the Standard Model” session

  3. DirectProduction Loopdiagrams Higgs-Yukawa Sector, EWSBNew Physics Introduction • Standard Model cannot be the final word • Hierarchy problem? Dark Matter? BAU? Why 3 generations? Patterns of masses & couplings? … • New physics at the TeV energy scale (LHC) • New gauge fields  new particles, new couplings • Can be probed via: • Direct production of new HEAVY particles. • Loop diagrams: A2 = |ASM+ANP|2 = |ASM|2 + |ANP|2 +2 |ASM||ANP|cosf • Heavy particles dominate in loops • Complementary approaches to uncovering New Physics Higgs-Yukawa Sector, EWSBNew Physics

  4. B0 mix/CPV Bs mix/CPV D0 mix/CPV Wolfenstein parameterization (, A, , ): A~0.8,l~ 0.22 1-2/2- 4/8  A3( - i) - 1-2/2 -4/8(1+4A2) A2 A3(1- - i) -A2+A4/2(1-2( + i)) 1- A24/2 + O(5) V = Magnitudes Phases 2 2 l + n Vub b W- u W+ CKM & Measuring its M.E.’s To diagonalize mass matrix, must use rotated states (3x3 Unitary  3 angles + 1 CPV phase) Unitarity  r,h in Vub, Vtd, Vts Only accessible in processes that probe these M.E.

  5. Lenz, Nierste, arXiv.0612.167 NP in Bd mixing NP in Bs mixing Much learned from B-factories and Tevatron. ImD(d,s) CKMFitter, arXiv.0810.3139 ~2s from SM in both! Great progress, but much room for NP • Need more precise m’ment of Bs mixing phase • CKM Angleg • Only CKM angle that can be measured from purely trees • Indirect g = (67.8+4.2-3.9 )o possible NP contribution • Direct g = (70+27-20 )o : from Trees, but large uncertainty. • With precise Dmd, Dms, sin(2b) in hand, and first meas. of sin(2bs), we may be seeing hints of NP.

  6. The LHCb Experiment LHCbis a first dedicated precision heavy flavor experiment searching for New physics in CP-Violation and Rare Decays at a hadron collider • Beams (intentionally) less focused Lint ~ 2 x 1032cm-2s-1 mostly single interaction. • 100K bb/sec expected and all B-hadron species produced: • B0, B+, Bs, Bc, b-baryons. • Yields ~102 - 106 / channel per 2 fb-1 • Forward, correlated bb production Single arm forward spectrometer 13 mrad<θ< 300 mrad (1.9<η<4.9)‏

  7. VeLo sIP~14+35/pT mm) st ~ 40 fs MUON (Trigger &m PID) RICH 1, 2 (PID: p,K,p) e(KK) ~ 96% e(pK,p) ~ 6% PRS/SPD (PID: e,g,p0) 144 mm 47 mm K K Bs K Ds  d~1cm 440 mm Bs→ DsK Bs →Dsp KK : ~96% pK : ~6% Spectrometer Silicon + Straws sp/p ~ 0.5% sM(Bhh)~20 MeV ECAL: ~9%/√E HCAL: ~70%/ √E Hadronic Trigger PID: e,g,p0,h,h...) The LHCb detector Example: Bs → Ds K s(t) ~40 fs Primary vertex LHCb is ready for data !

  8. fs or sin(2bs) Side note: 2 fb-1 == 1 nominal year’s running at LHCb (2x1032 cm-2 s-1)

  9. + CP Asymmetry isolates interference term • cc = J/ym+m- provides excellent trigger • ss detected in fK+K-, f0(980)p+p-,h()gg(p+p-) Observables: flavor tag, t Fit parameters: Dms ,DGs , fs ηf = CP eigenvalue fs (or 2bs )Anatomy • Analogous to B0J/yKs • Sensitive to New Physics in Bs mixing 2

  10. 0- 1-- 1– • 3 independent amplitudes • L=0, 2 CP+ • L=1 CP- total CP even CP odd flat background sin(2bs) in BsJ/yf • Must disentangle CP=±1. • Sensitive to angular distributions Transversity angles

  11. 10%rel. Asymmetry sin 2βs sin Dmst • s(2bs) ~ 0.07 with just 0.5 fb-1 2 fb-1 • s(2b)s ~ 0.035 • If 2bs 0.25s NP discoveryin 1st year of data! Bs vs Bs tags 10 x SM for visibility • Likelihood fit: • 6 observablesm, t, cosq, j, cosy,tag • 7 free parameters :fs, DGs, Gs, R┴, R||, d, d||Detector parameters fixed [Inclusion of S-wave component leads to ~10-20% reduction in resolution] Proper time (ps) BsJ/yf -- fs Analysis Signal: BsJ/ Control channels: • Acceptance:B J/ K*0 • Tagging: B J/ K*, B+J/K+, BsDs+- • Background:Sidebands Example acceptance plots (note zero suppression) 10%rel. 11

  12. BsJ/yf0(980), f0p+p- • See poster by L. Zhang at FPCP09 • Also, S. Stone and L. Zhang, Phys. Rev. D 79, 074024 (2009). • ss can form f0(980) • Estimate:based on the similar energy available for the (ss) system. • No angular analysis needed  increased single-event sensitivity • This mode looks very promising for LHCb

  13. fs mixing Summary (2 fb-1) • Sensitive to SM value before/by end of year 1 (2 fb-1) ! • NP discover could come beforeif sin(2bs) large-ish For 10 fb-1, scale down error by ~2.2

  14. Vtb Vts* f f s s Bsff • Penguin loop diagram. => Interference of direct decay and mixing • Vts appears in both decay and mixing. => cancellation of SM contribution of amplitudes => (VtbV*ts/V*tbVts)(V*tbVts/VtbV*ts) = 1 mixing decay =>But, new physics unlikely to cancel • Prediction of CP violation in SM < 1%. => Observation of any CP violation is signature for NP. • Again, PVV  angular analysis required. • Sensitivity: • 2 fb-1: Signal ~ 4K events, 0.4<B/S<2.1 at 90% CL (2bs) ~ 0.13 rad • 10 fb-1: ~20K events ~ 0.06 rad

  15. ( ) ( ) g Measurements in LHCb • B+D0K+ TREE, No Mixing -  gSM • D0/D0fCP , e.g. K+K-, p+p- (GLW): • D0/D0 CF, DCSe.g. K-p+, K+p- (ADS) + 3-body, 4-body • D0/D0 CF multi-body, e.g. D0Ksp+p- , KsK+K- (GGSZ) • D04-body, e.g. K+K-p+p- • B0D0K*0*(K+p-)Tree, Self-tagging -  gSM • Much the same issues/techniques as in B+ decay • Time-dependent analysis not required. • Dalitz analysis to extract D0K*0* amplitude (T. Gershon, PRD79, 051301 (2009)) • BsDsK & B0Dp gSM+fs • Time-dependent analysis necessary • Simultaneous fit with BsDsp • g with Penguins • Bp+p-/K+K-gSM+NP • BKpp and other 3 body modes GLW: Gronau & London, PLB253, 483 (1991), Gronau and Wyler, PLB265, 172 (1991) and Dunietz, PLB270, 75 (1991). ADS: Atwood, Duietz & Soni, PRL78, 3257 (1997) GGSZ: Giri, Grossman, Soffer, & Zupan PRD 68, 054018 (2003); also Atwood, Dunietz and Soni, PRD63 036005 (2001) More details in LHCb-2008-031, and references therein

  16. Interference between two O(l3) diagrams  large interference term • But, one bc(us) is color favored , the other bu(cs) is color suppressed Vub ( ) GLW: Use D0 fCP ADS: Interference between CF & DCS Decays Sensitivity to g through interference in D0/D0 CP final states  Large-ish rates  Small interference  rB • Large interference in (2) & (3)  Enhanced sensitivity to g  Low rates (DCSD) g in B-D0K- Vcb rB ~0.1

  17. ADS/GLW Two-Body Combined GLW Include both D0KK,pp ADS LHCb-2009-011 sg ~ 10-11o for 2 fb-1 ~ 5o for 10 fb-1 for rB = 0.10

  18. 2 fb-1 g in B+D0(Ksp+p-)K+ BaBar • CF, common final state: Much larger BFs. • Interference between the D0Kspp and D0Ksp+p- . • Relative strong phase shift DdD= dD(m-2,m+2) - dD(m+2,m-2) • Using flavor-tagged D0Kspp  ~7-9o model uncertainty • Use QC y(3770)D0D0 from CLEO-c ~2o model uncertainty! (PRD78, 092007 (2008)) Signal / 2 fb-1: ~ 5K B/S : ~ 0.5 sg ~12-13o / 2 fb-1 sg ~ 6o / 10 fb-1 LHCb-2008-028

  19. T. Gershon, PRD79, 051301 (2009)) The amplitudes in CF, DCS, and CP final states ( ) Form 2 ratios, AK* cancels (2 more for B0): • Here, AK* associated with the B0 decay and is therefore the same for all three cases. • Three corresponding equations for B0, g-g • 4 amplitude ratios • 3 unknowns: rB, dB and g! • Can be extended to other K* resonances ( ) g in B0D0K*0 Vub~e-ig bu bc • B0D0K*0, K*0K+p-not accessible in B0 decay  self tagging. • Both diagrams color suppressed! • rB~ 0.4 compared to ~0.1 in B+D0K+  larger interference term This mode looks extremely promising for LHCb, may provide the greatest sensitivity to g !

  20. Direct decay Phase relativeto Direct decay fs g+d Vts t Vtb s W W t Vtb* Vts* • Simultaneous fit for BsDsK, Dsp • Dsp ~140K/2 fb-1, constrains: wmistag, Dms, DGs, Gs • ~50% of events with no flavor tag included, provide some additional sensitivity. BsDsK: Signal ~ 7K/2 fb-1, B/S ~ 0.7 • BsDsK*, BsDs(Kpp) will also add sensitivity g in BsDsK • 4 time-dependent rates, 3 fit parameters (|l|, d, g+fs)

  21. CPV from interference between T&P with & without mixing Vub • 3 unknowns, 2 measurements.. ?Add BsK+K- and invoke U-spin symmetry KK pp Input: 2b & 2bs Allow for ±20%U-spin breaking sg ~10o / 2 fb-1 ~5o / 10 fb-1 g from Bpp,KK LHCb-2007-059 2 fb-1

  22. gindirect g Summary 10 fb-1: • g Trees: ~ 3o • g Time-dependent: ~5o • g Combined: ~ (1.9 – 2.7)o (depending on rB, dB) • g Penguins: ~ 5o gtrees (2011-2014)

  23. Jan Dec Feb Nov Mar Oct Apr Sept May Aug Jun Jul Summary • New Physics is not only about producing new particles. • Although that would clearly be tremendous! • New Physics should couple non-trivially with flavor. • Should lead to modified rates, CPV asymmetries, angular distributions, etc • Critical to measure CKM parameters in many different decays since we don’t know how the NP will manifest itself. • LHCb expects to expose these differences, if they are observable • Measurements of sin(2bs) and g could reveal NP within just 1 nominal year. • Also expect to break new ground in CPV in D0 decays • Many topics I did not have time to cover; apologies to my colleagues Special thanksto Wayne Stateand the organizingcommittee 2009 2010 2011 2012 2013 2014 The next few years should bequite exciting!

  24. Backups

  25. BsJ/yf Differential Rate

  26. What has B Physics taught us • Explosion of results over the last ~8 years. CKM describes major part of flavor-changing and CP violating effects. • New Physics a correction to LO CKM • Surprising we haven’t seen larger effects by now • But, there are tantalizing hints that New Physics may be around the corner • E.g. 2.2s tension in 2bs from the Tevatron M. Neubert, FPCP09 Widely disparate scales? Minimal Flavor Violation?

  27. B-Vertex Measurement 144 mm 47 mm K K Bs K Ds  d~1cm 440 mm Example: Bs → Ds K s(t) ~40 fs Primary vertex Vertex Locator (Velo) 21 stations of silicon strip detectors (r-f) ~ 8 mm hit resolution ~25 mm IP resolution • Trigger on large IP tracks • Measurement of decay distance (time)

  28. Momentum measurement OuterTracker 24 layer Straws shit~200mm Bs→ DsK Bs →Dsp By [T] measured TriggerTracker InnerTracker Bdl ~ 4 Tm 4 layers Si: ~200 mm pitch simulation Z [cm] sp/p~0.5%

  29. Particle Identification RICH: p/K/p identification using Cherenkov angle (rings) ,K Bs K KK : 97% pK : 5% K Ds  Primary vertex btag  • RICH1: 5 cm aerogel n=1.03 • 4 m3 C4F10 n=1.0014 RICH2: 100 m3 CF4 n=1.0005

  30. ECAL & HCAL: L0 trigger & Particle ID ECAL (inner modules): σ(E)/E ~ 8.2% /√E + 0.9% ECAL: Pb-Scint. HCAL Fe-Scint. e h • Level 0 trigger: high ET electron and hadron • Identify electrons, hadrons, p0, g

  31. Muon System: L0 trigger & Particle ID Pad MWPCsand GEMs m • Muon system: • Level 0 trigger: High Pt muons

  32. LHCb trigger Detector 40 MHz L0: high pT ~ 1-4 GeV(m, di-m, e, g, h, di-h…) [hardware] 1 MHz 16000coreonlinefarm HLT1: Confirm L0 w/ tracking in ROI; pT, IP cuts ~30 kHz • Inclusive selections • Ex: Single high pTm, di-m, J/y, 2h, 3h, 4h • Exclusive selections : • Ex: B(s)D(s)h(*), ff, K*ll, p+p-p0, p+p-, K+K-, HLT2: full reconstruction of event To tape: 35 kB @ 2 kHz

  33. D0Kpp0 has large coherence and BF~14%! investigations underway…stay tuned … Additional ADS:B+D0(K-p+p-p-,K-p+p0)K • Interference over the D0K-p+p-p+ Dalitz • RK3p is the Coherence factor [0-1]  Bigger is better ! • dK3p is the strong phase diff. averaged over the Dalitz plot • These have been measured with CLEO-c • Low coherence in B+D0(Kppp)K+, but does help in global fit to constrain rB. See: arXiv.0903.4853

  34. CPV in D0 Decays • CPV in D0 decays expected to be at the level 10-3. • ~108 D*+D0(hh)ps+ / 2 fb-1 (~50% from B, 50% prompt) • Any CPV at the level of even 1% would be a signal for NP. • One example: CPV in SCS decays < 0.1% in SM

  35. Recent News on BsJ/yf G. Punzi, EPS09, Krakow

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