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Rare B and decays and searches for New Physics. Roger Barlow Manchester University and. New (preliminary) results, mostly but not entirely from the B factory experiments Belle and BaBar. b. +. H +. u. . Why look for Rare Decays?.
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Rare B and decays and searches for New Physics Roger Barlow Manchester University and New (preliminary) results, mostly but not entirely from the B factory experiments Belle and BaBar.
b + H+ u Why look for Rare Decays? Our chance to see them is when the Standard Model amplitudes are small: Rare decays If new particles are to appear on-shell at high energy colliders, they must appear in virtual loops and affect amplitudes Roger Barlow: Rare B and tau Decays and New Physics
What made it possible? Measuring Branching ratios of ~10-6 needs millions of events Physics progress possible thanks to machine physicists at SLAC and KEK • designed and built B factories operating in a new high-current regime, • continually faced and overcame new problems and challenges. • design luminosities met and exceeded. Roger Barlow: Rare B and tau Decays and New Physics
“Finding a needle in haystack.” Huge backgrounds from other Bs and e+e-qq E(GeV) Use of E=EB-Ei and MES=EB2-(pi)2 Use data sidebands (rather than Monte Carlo) to estimate background “Blind Analysis” Tune cuts without looking in the MES-E ‘signal box’ MES(GeV/c2) (taken from Sekula’s talk. One of many) Roger Barlow: Rare B and tau Decays and New Physics
Other Experimental techniques Continuum suppression from combined information from shape variables “Single-B beam” technique: Reconstruct one “tag” B in a common decay mode (hadronic or semileptonic). Remaining particles must also form a B Limits from N= S + b N small Uncertainties on , b Roger Barlow: Rare B and tau Decays and New Physics
Contents • B decays • Leptonic • Radiative • bs and bs l + l - • bd and bd l + l - • Hadronic Charmless • Branching Fractions • Charge Asymmetries • Polarisation • Tau decays Roger Barlow: Rare B and tau Decays and New Physics
W + b u,c,t b b W + + - W+ H+ d,s u u B Decays to leptons Proceeds through one or two weak bosons with strong CKM suppression – door open for NP particles to contribute Free of hadronic uncertainties in final state Plus many other diagrams b + ~ d,s - Roger Barlow: Rare B and tau Decays and New Physics
B CP, Rare decays, CKM V Browder (Belle) Sekula (BaBar) Important as W (suppressed by Vub) can be replaced by charged Higgs, etc Difficult due to neutrinos in the final state tag with fully reconstructed B mesons (180 channels) Tag with BD(*)l SM prediction (1.59 0.40) x 10-4 (depends on fB and Vub) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM V Browder (Belle) Sekula (BaBar) B Identify possible in common decay mode Look at extra calorimeter energy (validate with for D*ln) H+? Extra E(GeV) Extra E(GeV) Roger Barlow: Rare B and tau Decays and New Physics
Results (revised). 3.5 significance (new) BF(B++)= (0.88 0.11) x10-4 BR< 1.80 10-4 @ 90%CL +0.68 -0.67 Belle and BaBar results are similar. Agree within errors Can be combined (R. Faccini) to give (1.36 0.48)x10-4 BF(B++) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM V Browder (Belle) Impact Limits on e.g. 2 Higgs doublet model: W.S.Hou, PRD 48, 2342 (1993) SM prediction enhanced/reduced by factor rH Or: Within the SM, use the value of BF(B++) to give a measurement of fB Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM V Sekula (BaBar) B and e Helicity Suppressed Use hadronic tags: B fully reconstructed as B to D(*) X Lepton is monoenergetic in signal-B rest frame Limits (@ 90% CL) <7.9 x10-6 for e(SM ~ 10-12) <6.2 x10-6 for (SM ~ 10-7) Lepton momentum in B frame (GeV/) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM V Sekula (BaBar) B0 to l l FCNC and helicity suppressed, but an initial state photon allows helicity flip SM predictions of order 10-10 (10-15, 10-11 respectively without the ) See 0 events for e, 3 events for (but compatible with background) Limits (at 90% CL) BR(Bee)< 0.7 x 10-7 BR(Bmm)< 3.4 x 10-7 (simulated) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM V Browder (Belle) B K* Tag on other B Identify K* Look for extra energy SM prediction ~1.3 x 10-5 Signal is BK* + missing mass. (Could be light dark matter particle: publications by M. Pospelov et al.) Extra Calorimeter Energy (GeV) (at 90% C.L) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM IV-V Farrington (CDF) Strauss (DØ) Sivoklokov (ATLAS) Langenegger (CMS) Ruf (LHCb) B0 +- SM predicts Bs:(3.40.5)x10-9 Bd:(1.00.1)x10-10 NP can boost this by ~100 B0s +-B0d +- LHC experiments will do this very precisely DØ analysis not yet complete. Combines Bs and Bd. Expect limit ~ 2 10-7 Have result on BR(B ) BR < 4.1 x10-6 @ 95% Roger Barlow: Rare B and tau Decays and New Physics
Radiative B decays FCNC process suppressed in SM: sensitive to new particles in loops bs Inclusive and many exclusive measurements bsl+l -: More information from kinematics bd : strongly suppressed but open to different physics bd l+l-: on the way Roger Barlow: Rare B and tau Decays and New Physics
HFAG average (3.55 0.24 0.03) x10-4 +0.09-0.10 Heavy Quark Physics I &III Hurth (Theory) Convery (BaBar) B s inclusive ‘Fully Inclusive’ and ‘sum of exclusives’ (38 modes) Branching Fraction now well measured. Theory and experimental error similar +0.37 -0.49 NLO calculation (3.61 ) x10-4 result: (Eg >1.9GeV) = (3.67 0.29 0.34 0.29) x10-4 Not much room for New Physics here Constrains model builders Roger Barlow: Rare B and tau Decays and New Physics
B s exclusive Heavy Quark Physics III Limosami (Belle) • Lots of channels • Branching Fractions measured • CP violating asymmetries measured If nonzero these would be a signature of New Physics Example: B K0s0 t(ps) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM VI Kovalskyi (BaBar) BSM VI Hamel de Monchenault B Kl l B K*l l Standard Model Amplitudes have 3 parts with different kinematics. Check out each separately through Wilson Coefficients: Photon C7 Vector EW C9 Axial EW C10 CKM factors x Ci(q2) x local operators BKll (46 events) Dilepton mass q2 MES(GeV/c2) E(GeV) Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM VI Kovalskyi (BaBar) Angular variables e.g.*: angle of l l pair in their rest frame. C10 interferes with C7/C9 to give asymmetry K*ll Asymmetry as a function of q2 Roger Barlow: Rare B and tau Decays and New Physics
B++ B00 B d CP, Rare decays, CKM VI Kovalskyi (BaBar) First observation of B++ MES(GeV/c2) Roger Barlow: Rare B and tau Decays and New Physics
+0.018 -0.021 +0.017 -0.014 |Vtd/Vts|=0.171 Compare with BK* CP, Rare decays, CKM VI Kovalskyi (BaBar) Same CKM elements as mixing – but a non-trivial test W d,s b t t W b d,s ds t Roger Barlow: Rare B and tau Decays and New Physics
B l +l - CP, Rare decays, CKM VI Kovalskyi (BaBar) Prediction: few 10-8 Measure B + +l +l - and B0 0l + l - with l =e or (and e - ) Total limit 7.9 x 10 -8 at 90% CL for B+ ( twice B0) Amazing to be probing at this level E(GeV) E(GeV) MES(GeV/c2) MES(GeV/c2) Roger Barlow: Rare B and tau Decays and New Physics
Charmless Hadronic Decays • Many modes • Will present collected branching ratios • Will present measurements of time-integrated CP violation ACP: they follow on directly from differences in charge conjugate decay states • from the B+/B- difference - trivial • From self-tagged neutral modes – trivial • From C part of CP+mixing fit – nontrivial but standard Roger Barlow: Rare B and tau Decays and New Physics
Heavy Quark Physics I Dragic (Belle) Bona (BaBar) Examples MES(GeV/c2) MES(GeV/c2) E(GeV) Roger Barlow: Rare B and tau Decays and New Physics
Heavy Quark Physics I Dragic (Belle) Bona (BaBar) 2 body -K combinations Results on many other decays. See talks by Dragic, Bona, Latham and Schümann in Heavy Quark Physics Session I Roger Barlow: Rare B and tau Decays and New Physics
CP, Rare decays, CKM IV Di Marco (BaBar) Unno (Belle) B K+- /K-+ Direct CP violation Experiments agree: BaBar: ACP=-0.108 0.0240.007 Bel ACP=-0.093 0.0180.008 Roger Barlow: Rare B and tau Decays and New Physics
Direct CP in K Competing amplitudes with different strong and weak phases ACP should be the same for K+- and K+0 (Gronau: hep-ph 0508047) Current averages (HFAG) ACP (K+-)=-0.093 0.015 ACP (K+0)=+0.047 0.026 Difference 0.14 0.03 – a long way from zero Maybe colour-suppressed trees are responsible Maybe New Physics Roger Barlow: Rare B and tau Decays and New Physics
Lipkin Sum Rule RLipkin=2(B+K+0)+(B0K00) (B+K0+)+(B0K+-) From isospin and assuming the b s penguin diagram dominates R should be 1+O(10-2) Obtain (HFAG average) RLipkin=1.06 0.05 (Was 1.25 0.10 in 2003) Roger Barlow: Rare B and tau Decays and New Physics
Heavy Quark Physics I Dragic (Belle) BK ratios Can form many ratios, especially (A Buras, R Fleischer et al, Phys J C 45 (701-710) 2006) Rn=(K+-)Rc=2 (K+0) 2 (K00) (K0+) Obtain (HFAG averages) Rn=0.99 0.07 Rc=1.11 0.07 Agree with each other And with SM predictions The “K puzzle” is no more Roger Barlow: Rare B and tau Decays and New Physics
The Polarisation Puzzle B V V decays are spin 0 to spin1+spin1 Should be 100% longitudinally polarised (if tree or penguin dominates) Measurements confute this – for heavier V especially Needs to be understood – affects CP decomposition More data now available Roger Barlow: Rare B and tau Decays and New Physics
CP, rare decays, CKM III Telnov (BaBar) B 00 See 98 22 events - 3 significance BR (1.16 0.27)10-6 +32 -31 +0.36 -0.37 E(GeV) Fit longitudinal polarisation fl= 0.86 0.05 Measurement needed for B 0+- , used for alpha Informs penguin uncertainty in determination MES(GeV/c2) +0.11 -0.13 Roger Barlow: Rare B and tau Decays and New Physics
Heavy Quarks I Bona (BaBar) B K* and f(980)K* fL around 0.5, as in B K* as opposed to ~1 from simple models Roger Barlow: Rare B and tau Decays and New Physics
CP, rare decays, CKM VI Bussey (CDF) More on B to V V CDF measure longitudinal polarisation in K*, K* Confirm BaBar and Belle results that polarisation is not 100% on the way M(K) (GeV) Roger Barlow: Rare B and tau Decays and New Physics
BSM VI Hayasaka Rare Tau Decays Search for New Physics in decays with Lepton Flavour Violation The B factories are also factories (+ -) = 0.89 nb ats = M() Total sample of ~1.5 billion tau leptons Roger Barlow: Rare B and tau Decays and New Physics
BSM VI Hayasaka Compendium of results Roger Barlow: Rare B and tau Decays and New Physics
m signal event g t e e t generic t decay General techniques Divide event into two hemispheres ‘Tag side’ usual 1prong (e, , , ) or 3 prong decay. Different analyses use different tags, trading purity for numbers. ‘Signal side’ with no neutrinos. Powerful energy/momentum constraint. Roger Barlow: Rare B and tau Decays and New Physics
BaBar result Excluded region Belle result BSM VI Hayasaka l l K0 l is or e. Theoretical predictions vary from ~10-40 for SM (with mixing) upwards New 90% CL limits Br ( - e -g ) < 12 x 10-8 Br (-m-g ) < 4.1 x 10-8 Br (t- e -KS) < 5.6 ×10-8 Br (-m -KS) < 4.9 ×10-8 (hep-ex/0605025) Tan Roger Barlow: Rare B and tau Decays and New Physics
BSM VI Hayasaka - -, K -, -, K – Look for B-L conserved processes as allowed in the Standard Model Look for B-L violating processes as Baryogenesis may need them E(GeV) Decays to non-strange baryons ruled out through proton lifetime measurements Roger Barlow: Rare B and tau Decays and New Physics
% % g % g % g BSM VI Hayasaka • in and 3 modes • Limit 1.6 x10-7 @ 90% CL (BaBar) • 0.65 x10-7 @ 90% from Belle MSSM prediction Tan MA(GeV/c2) Roger Barlow: Rare B and tau Decays and New Physics
BSM VI Besson(CLEO) Y(1S) CLEO result on Lepton flavour violation Detect through decay to e pe/Ebeam (e) BR< 6.2 10-6 LFV Scale >1 TeV p/Ebeam Roger Barlow: Rare B and tau Decays and New Physics
BSM VI Hamel de Monchenault Putting it all together An example: MSSM parameter space Isidori and Paradisi hep-ex 0605012 One set of Parameters {,AU, sparticle masses} Restrictions on MH, Tan Due to bs Bs g-2 MB B Tan M(H+) Roger Barlow: Rare B and tau Decays and New Physics
Conclusion BaBar and Belle are probing physics at the TeV scale, exploring parameter spaces of proposed New Physics models Limits on Higgs Masses, Tan , SUSY particles. Precision Frontier and Energy Frontier are Complementary. LHC results will benefit from Rare Decay information. Standard Model beginning to be heavily stressed A SuperB factory would stress it even further Roger Barlow: Rare B and tau Decays and New Physics