Prospects of rare B decays at high luminosity B factories Nobu Katayama KEK

July 13, 2001Nobu Katayama2 High luminosity B factories 4.4  cm  2 s  1 (KEKB, peak luminosity) –gives 5  10 7 BBbar pairs/year Luminosity goal of HLBF:10 35 cm  2 s  1 –10 9 BBbar /year Competition with the hadron collider experiments –10 32 cm  2 s  1 gives BBbar /year –a factor of 100 will be overwhelming for rare B decays? Yes and no

July 13, 2001Nobu Katayama3 Possible Belle run plan Date Int. Lum. (fb  ) Comments May 5, (on 4S)Summer conf Jul. 15, on, 3 offJournal papersSoon! Summer 2002~10060/year10 8 B’s By ~50060~100/year By ~ ~1000/year10 9 B’s

July 13, 2001Nobu Katayama4 How I estimated Many conventional measurements on the sides of the triangle are already systematically limited Measurements on the phase and branching fractions and other parameters that are sensitive to New Physics are not yet systematically limited –Estimations of the measurement accuracy based on the current Belle analyses are given –Will not quote the central values of the Belle measurements but discuss the errors only

July 13, 2001Nobu Katayama5 Rare B decays Modes for angle measurements –not covered by this talk Modes for “beyond the SM” search are discussed –B  X s,d  –B  X s,d ll –B  X s,d –Exclusive decays of the above –B  ll,l –B  D* 

July 13, 2001Nobu Katayama6 BXsBXs Theory(SM):    –By P. Gambino and U. Haisch Experiment:    –CLEO, ALEPH, BELLE combined CLEO:    inclusive –using 9.7M BBbar

July 13, 2001Nobu Katayama7 Inclusive B  X s factories  Br(B  X s  )     with 30 fb  –~10% error (statistical + systematic) from the semi exclusive measurements –Experiments at the B factories take only 10% off- resonance data and they must be clever about the subtraction  Br(B  X s  ) <    Br/Br  by 2006 –By summing all exclusive measurements ? –Inclusive photon spectrum above 2GeV (The new CLEO measurement) ?? Most likely, B factories do better than hadron machines

July 13, 2001Nobu Katayama8 Exclusive B  K x  decays  Br(B  K*(832)  )=    with 30 fb  –<10% error (statistical + systematic)  Br(B  K x  )=    with 30 fb  –B  K  and B  K  are now being analyzed –resonance structure, spin analysis  Br(B  K*(832)  )=    by 2006 –~3% error  Br(B  K x  )=    by 2006 –5~20% error on higher resonances Modes involving neutrals will also be understood very well

July 13, 2001Nobu Katayama9 B  X s  CP asymmetry  A cp (B  X s  )=  ~  with 30 fb   A cp (B  K*(832)  )=  ~  with 30 fb  S.E.S.(B  K 1  )~    with 30 fb    A cp (B  X s  )=  ~  by 2006  A cp (B  K*(832)  )=  ~  by 2006  A cp (B  K 1 , indirect) =~  by 2006

July 13, 2001Nobu Katayama10 Inclusive B  X d  B  X d  :Large background from b  s  –very good particle identification devices in order to separate X d from X s –understanding the performance of the PID devces –qq  and continuum backgrounds are much larger than s  case. B  X d  inclusive branching fraction semi-exclusively by 2011? –Need to study more

July 13, 2001Nobu Katayama11 B  X s ll Theory(SM): –Inclusive    –Br(B  K *  ) =    Experimental limits (CLEO 2001) –9.6M BBbar –Br(B  Kll) <    –Br(B  K*(892)ll) m ll >0.5GeV/c 2 <   

July 13, 2001Nobu Katayama12 B  X s ll Single event sensitivity/10fb  (10  BB), Belle –K +    1.21  10  –K +  4.41  10  –K +   ee 1.56  10   10~30% error on exclusive b.r. by ~10% error on exclusive b.r. by 2011 Inclusive measurements, A fb, m ll will have similar fractional errors B factories are better for low m ll region

July 13, 2001Nobu Katayama13 B  ll and  B  l Theory(SM): –Br(B  )=    –Br(B  )=    –Br(B  )=    Experimental limit (CLEO 2000) –Br(B  ) <    –Br(B  <   

July 13, 2001Nobu Katayama14 B  ll and  B  l SES with 30 fb , Belle – B  0.8  10  Belle on Br(B  ) with 20 fb  –  Br(B  ) ~ 2    No chance to observe if SM but if the b.r is ~10  we can observe by 2006 and 10 , 2011 If SM, we might be able to observe  by 2011

July 13, 2001Nobu Katayama15 B  X s  B  B  D*  One side of the event (B) must be reconstructed. Efficiency ~ 10  The same analysis technique Single event sensitivity/10fb  (10  BB) –X s,  10  –D*  10   ~30% error on Br(X s ) by 2011 ~10% error on Br(  ) by 2011 D*  ~100 events by 2006

July 13, 2001Nobu Katayama16 BKsBKs Single event sensitivity/10fb  (10  BB), Belle –  K s 2  10  –  K + 6  10   10~20% error on Br(  K s ) by ~10% error on Br(  K s ) by 2011 Asymmetry error: < 0.2 by 2011

July 13, 2001Nobu Katayama17 Summary Belle has started analyses of many decay modes/asymmetries discussed here. Most of estimations are based on the numbers we already measure (but have not announced!) Others are just wild guesses. Sorry, if they are wrong by more than factor 3 There could be a discovery of new physics with < 500 fb  but even with 4000 fb , some parameters may not distinguish new physics from the SM