Andrey Golutvin Moriond Prospects of search for New Physics in B decays at LHC Andrey Golutvin ITEP / Moscow - In CP - violation - In rare decays

2 In CP-violation

3 Inputs: Accuracy of sides is limited by theory: - Extraction of |Vub| - Lattice calculation of Accuracy of angles is limited by experiment: = ± 13°  = ± 1.5°  = ± 25° Mean values of angles and sides of UT are entirely consistent with SM predictions 3

4 Define the apex of UT using at least 2 independent quantities out of 2 sides: and 3 angles: ,  and  Extract quantities R b and  from the tree-mediated processes, that are expected to be unaffected by NP, and compare computed values for with direct measurements in the processes involving loop graphs. Interpret the difference as a signal of NP Standard strategy to search for New Physics

5 At present the sensitivity of standard approach is limited due to: - Theoretical uncertainties in sides - Experimental uncertainties in  and  angles - Geometry of UT (UT is almost rectangular) Comparison of precisely measured  with  is not meaningful due to error propagation: 3° window in  corresponds to (24  5)° window in  5

6 Precision comparison of the angle  and side Rt is very meaningful !!! ~5% theoretical precision in Rt is adequate to a few degree experimental precision in the angle  which should be achievable after 1 year of LHC running Precision measurement of  will effectively constrain Rt and thus calibrate the lattice calculation of the parameter

7 b q1q1 d, s q2q2 W−W− g d (s) q q W − bu,c,t b q q b W+W+ W−W− V* ib V iq V* ib trees d-/s- penguins d-/s- boxes m b γ L +m q γ R b q W–W– u, c, t Z, γ d (s) l+l+ l−l− W − bu, c, t Compare experimental observables measured in different topologies: Complementary Strategy

8 trees vs box loops vs penguin loops In trees:  (tree) is measured in B  J/  Ks  (tree) =  -  (tree) -  (tree)  (tree) is measured in B  J/  Precision measurements of angles in tree topologies should be possible. Eventually LHCb will measure , , and  with  (  ) ~ 0.5°,  (  ) ~ few° and  (  ) ~ 1° precision respectively Theoretical uncertainty in Vub extraction |VtsVtb*| and UT angles: ,  and 

9 For the angles: (theoretically clean) Measure  (peng) in B  , ,   (peng) in B   Ks  (peng) in Bs   New heavy particles, which may contribute to d- and s- penguins, would lead to some phase shifts in all three angles:  (NP) =  (peng) -  (tree)  (NP) =  (B   Ks) -  (B  J/  Ks)  (NP) =  (B   ) -  (B  J/  ) For |VtsVtb*| (at the moment not theoretically clean) : Proposed set of observables Theoretical input: improved precision of lattice calculations for B × f B and B  , ,K* formfactors Experimental input: precision measurement of BR(B  K* ,  )

10 Contribution of NP to processes mediated by loops ( present status) To boxes: -  vs Rb is limited by theory (~10% precision in Rb) (d-box) -  poorly measured at the moment (s-box) To penguins: -  (  (NP)) < 30° (d-penguin) -  (  2  (NP)) ~8° (2.6  hint) (s-penguin) -  (  (NP)) not measured yet (s-penguin) PS  (NP) =  (NP)

11 Angle ChannelYield*B bb /SLHCb (2/fb)  B d  J/Ψ K S B d   K S 216k 0.8k 0.8 <2.4 σ(  ) ≈ 0.6 ° σ(  ) ≈ 12 ° ss B s  J/ΨΦ B s  J/Ψη B s  η c Φ B s  ΦΦ 125k 12k 3k σ(  s ) ≈ 1.2° σ(  s ) ≈ 6° (2° with 10/fb)  B s  D s K B d  D 0 (K -  + )K* 0 B d  D 0 (K +  - )K* 0 B d  D CP (K + K - )K* B -  D 0 (K +  - )K - B -  D 0 (K -  + )K - 5.4k 0.5k 2.4k 0.6k 60k 2k <1.0 <0.3 <2.0 < σ(  ) ≈ 13 ° σ(  ) ≈ 8 ° σ(  ) ≈ 4 ° -13 °  B d   14k 0.8 σ(  ) < 10 ° ATLAS: similar to LHCb sensitivity in  with 30 /fb  (  s ) ~ 0.08 (10/fb, m s =20/ps, 90k J/ evts) CMS:  (  s ) ~ 0.07 (10/fb, on J/ evts, no tagging) LHCb (see M.John talk)

12 In Rare Decays

13 - Radiative penguins - Electroweak penguins - Very rare decays Bs,d  , e  Experimental challenge: keep backgrounds under control

14 Exclusive radiative penguins LHCb control channel: B d  K*  ~75k signal events per 2fb -1 13

15 Radiative Penguin Decays Measurement of the photon helicity is very sensitive test of SM Methods: - mixing induced CP asymmetries in B s  , B  K s  0  -  b   : asymmetries in the final states angular distributions are sensitive to the photon and  b polarizations. - Photon helicity can be measured directly using converted photons in B  K*  decay or parity-odd triple correlation (P(  ),[ P(h 1 )  P(h 2 )]) between photon and 2 out of 3 final state hadrons. Good examples are B   K  and B  K  decays b   (L) + (m s /m b )   (R)

16 Polarized  b decays:  b   (1115)   (1115)  p  violates pariry Assuming  b polarization > 20% LHCb can measure  (R) component down to 20% (in 1 years of data taking). Limitation - low annual yield (~675 events)  requires efficient performance of tracking system. Mixing induced CP asymmetries - B  B  K s  0  (B-factories) S = - (2+O(  s ))sin(2  )m s /m b + ( possible contribution from b  s  g ) = ± P.Ball and R.Zwicky hep-ph/ Present accuracy: S = ± 0.40 (BaBar : 232M BB) S = ± 0.31 (BELLE: 535M BB) - Bs    ( LHCb annual yield ~11 k, B/S ~0.6 )

17 Measuring the photon polarization in B  h 1 h 2 h 3  decays The measurement of the photon helicity requires the knowledge of the spin direction of the s-quark emitted from the penguin loop. Use the correlation between s-spin and angular momentum of the hadronic system (needs partial-wave analysis !!!) Promising channels for LHCb: Expected yield per 2 fb-1 BR(B +  K +  -  +  ) ~ 2.5  rich pattern of resonances ~60k BR(B +  K +  ) ~ 3  highly distinctive final state ~ 7k Sensitivity to photon helicity measurement is being studied M.Gronau,Y.Grossman,D.Pirjol,A.Ryd PRL 88, 5, 2002 D.Atwood,T.Gershon,M.Hazumi,A.Soni hep-ph/ v 1 V. Shevchenko paper in preparation

18 B d → K *   decay BdBd   s b  K* In SM, the decay is a b → s penguin diagram But NP diagrams could also contribute at the same level dd For 2 fb -1 LHCb expects 7200±2100 signal events.(Uncertainty mostly due to BR) with a B/S < 0.5 Branching ratio:( )   n addition to the virtual photon, there will be Z 0 contributions  Which will add some calculable right handed contributions.  But these could be added to by New Physics  Resulting in modified angular distributions

19 18

20 Kreuger, Matias hep-ph/ Prospects for Forward-Backward asymmetry measurements (see M. John talk)

21

22 LHCb prospects

23 Rare decays: B s →   for LHCb prospects see M. John talk)  Very small branching ratio in SM: (3.4 ± 0.5) x  Present limit from Tevatron at 95% CL(1 fb -1) : < 7 x  Expected final limit at 95% CL (8 fb -1 ): < 2 x  Sensitive to New Physics through loops  Could be strongly enhanced by SUSY. ? ? MSSM

24 Example: constrained minimal SSM: CMSSM Anomalous magnetic moment of muon: Measured at BNL, disagrees with SM at 2.7 .  a m = (25.2 ±9.2) To explain it with CMSSM: for different A 0 and tan  : 250 < m 1/2 (gaugino mass) < 650 GeV CMSSM with this same range of gaugino mass predicts BR (B s → m + m - ) could be ~ a few to much higher than SM:      

25 LHC Prospects Limit at 90% C.L. (only bkg is observed) Integrated Luminosity (fb -1 ) BR (x10 -9 ) Uncertainty in bkg prediction Expected CDF+D0 Limit SM prediction LHCb Sensitivity (signal+bkg is observed) Integrated Luminosity (fb -1 ) BR (x10 -9 ) 55 33 SM prediction

26 Important measurements to test SM and Search for NP In CP-violation: -  vs Rb and  vs Rt (Input from theory !) -  : if non-zero  NP in boxes -  (NP),  (NP) and  (NP): if non-zero  NP in penguins In rare decays: -Photon helicity in exclusive radiative penguins - Measurement of FBA, zero point, transversity amplitudes in B  sll exclusive decays (K* , , …) - Measurement of BR(B s,d   ) down to SM predictions - Search for lepton flavor violation