1 Searching for New Physics in Beauty and Charm Brendan Casey Brown University Stony Brook HEP Seminar February 13, 2007 2 What is new physics? Current theories explain the entire dynamics of our universe from about 1 second after birth. What was happening before the 1 st second? New physics is what ever it takes to answer this question. 3 Matter at t 1 second: BBN Burles, Nollett, Turner astro-ph/ Evolution of light elements in first hour of the universe Extraordinary success of GR, astro, particle, nuclear physics But: Small excess of baryons is an initial condition of BBN, not a prediction. No explanation of the evolution of anti- elements 4 CPV: Standard Model to the rescue? mass basis, d,s,b weak basis, d, s, b quarks: d I = V ij d j antiquarks: d i = V ij *d j Provides a mechanism to generate a net baryon number through decay of heavy to light particles V ub V ub *, V td V td * CPV production decay 5 Standard Model CPV Mag(CPV) f(m 2 j -m 2 i ) f( ij ) sin CP Three properties govern size of CPV in SM: quarks: Large mass splitting Small mixing angles Large CP neutrinos: small mass splitting large mixing angles CP ? ~15 orders of magnitude too small Huet, Sather PRD (1995) Jury still out Need new sources of CPV! More generations, more interactions.new particles 6 Direct versus Indirect Year quark mass (GeV/c 2 ) t t 1 TeV p 5 GeV B t t b d b d W W charm discovered 1974 bottom discovered 1977 top discovered 1995 charm predicted, mass scale set by K 1970 bottom and top predicted from CPV in kaon mixing 1973 Top mass scale set from B d mixing 1987 direct indirect 7 Cast of Characters Mesons B 0 : ( b d ), B s : ( b s ), D + : ( c d ), D s : ( c s ) Flavor Changing Interactions b t s b t s Box: Penguin: 8 Apparatus 9 The Tevatron and D Detector 400 MeV 150 GeV ~1 TeV + 1 TeV 10 Why the Tevatron? Dont they do B physics at B factories now? B factory on L = cm -2 s -1 L = cm -2 s -1 B production rate~10 Hz~1 kHz B s production rate0~100 Hz Longitudinal boost~0.5~1-2 Transverse boost~0~1-2 Tevatron is the only B s factory 11 Why D? Excellent muon identification Large semileptonic B samples ideal for mixing and CPV studies Uranium Iron 12 Why D? Excellent vertexing capabilities for flight length determination Just enough resolution to probe SM expected value of the B s mixing frequency Error on the flight length determination 13 Tevatron Data Set >2.3 fb -1 delivered FY01 FY02 FY03 FY04 FY05 FY06 FY07 Run IIa: 1.3 fb -1 on tape Run IIb: 700 pb-1 analyzed 14 Tevatron Data Set >2.3 fb -1 delivered FY01 FY02 FY03 FY04 FY05 FY06 FY07 Run IIa: 1.3 fb -1 on tape Run IIb: 700 pb-1 analyzed Fast turn around in the heavy flavor group fb -1 results last winter Pushing for close to 2 fb -1 results this winter 15 B s Mixing 16 General rule of neutral flavor changing processes: New physics: Second order loop or box New particles can enter the loop SM contribution is suppressed Precision SM tests: no new physics? Measure fundamental Standard Model parameters clean in B mesons b quark is heavy, top loop dominates. Every measurement of mixing has lead to a major discovery: K: CPV, 3 rd generation, B d : top mass, : neutrino mass Why Mixing? b ??? s b t V td(s) s,d Rate ( m t / m W ) 2 s,d 17 Analysis Overview ++ K+K+ KK +,e + q B s Candidate Recoil system Primary and secondary vertices Reconstruct the B s in a flavor specific final state Determine lifetime in the B s rest frame Determine initial flavor by studying recoil system Extract the mixing frequency from the time dependence of mixed and unmixed samples 18 Mixing Frequency Extraction Reconstructed decay length (cm) 19 Mixing Frequency Extraction Reconstructed decay length (cm) Looking for this Reconstructed decay length (cm) 20 Mixing Frequency Extraction Reconstructed decay length (cm) Perform a Fourier analysis of the decay length distribution to extract the mixing frequency Power Spectrum for winter data set Time domain Frequency domain 1/ m mm 21 Winter 06 Mixing Frequency Results m s < 21 ps 90% CL Maximum likelihood at m s = 19 ps -1 1 fb -1 First time m s bounded on both sides!!!!! Change in log(L) versus m s D s only 22Reflections m( ) m( S ) D s K*K D + K c pK D s K S K D + K S c K S p Original results based on D s Needed to add more channels: K*K and K S K Difficult to include these modes without particle identification 23 Taming Reflections Momentum asymmetry between K S and K candidate Take advantage of the fact that the mass shift is a function of the particle momentum D + K S MC m( S ) m( * ) High p low p 24 Fall 06 Results K*K e S Extra data cured fluctuation 25 Time Evolution of Results LEP/SLD/CDF I were able to exclude values below about 15 ps -1 New Physics Realm msms LEP/SLD Era SM expectation 26 Time Evolution of Results March 06: D provides first upper bound on the B s oscillation frequency. Rules out large new physics effects at high confidence level. Still 5% chance of background fluctuation. msms New Physics Realm SM expectation D, March 2006 27 Time Evolution of Results Confirmed by CDF in April >5 measurement Fall Closes the chapter on the magnitude of the Bs oscillation frequency. msms New Physics Realm SM expectation Tevatron Era 17.7+/ ps -1 28 Indirect Searches so far Now reached SM level for one of our key indirect NP search modes, m s. No new physics. Not just a Tevatron problem, problem for B physics in general. Choice: Wait for new energy frontier Expand current physics program beauty charm 29 Flavor Changing Neural Current Charm Decay 30 Up versus Down Generation Mass (MeV/c 2 ) up line q = 2/3 down line q = 1/3 t c u d s b 31 Up versus Down Generation Mass (MeV/c 2 ) up line q = 2/3 down line q = 1/3 t c u d s b Very different mass hierarchy 32 Up versus Down Generation Mass (MeV/c 2 ) t c u d s b c u b W+W+ WW up FCNC ~ ( m b / m W ) 2 WW W+W+ b s t down FCNC ~ ( m t / m W ) 2 33 Up versus Down Generation Mass (MeV/c 2 ) t c u d s b c u b W+W+ WW up FCNC ~ ( m b / m W ) 2 WW W+W+ b s t down FCNC ~ ( m t / m W ) 2 Down the down line: suppressed but measurable (eg. mixing) Down the up line: almost impossible for SM, any signal = new physics 34 Why 3 body FCNC charm? D + m( GeV) (1/ )(d /dm 2 ) GeV -2 ) Long distance Short distance c u Two processes: Long distance (strong scale), short distance (weak scale) Clear separation of long distance and short distance components New Physics only effects short distance. (rare clean channel) c s s u d D+D+ ++ D D 35 New Phenomena in c u New Phenomena in c u Strict limits from b s, interesting scenarios effect up sector quarks and not down sector quarks. 36 New Phenomena in c u New Phenomena in c u Strict limits from b s, interesting scenarios effect up sector quarks and not down sector quarks. D + m( GeV) (1/ )(d /dm 2 ) GeV -2 ) RPV in the up sector and not the down sector Burdman et al. hep-ph/ c u 37 New Phenomena in c u New Phenomena in c u Strict limits from b s, interesting scenarios effect up sector quarks and not down sector quarks. D + m( GeV) (1/ )(d /dm 2 ) GeV -2 ) RPV in the up sector and not the down sector Burdman et al. hep-ph/ c u Little Higgs models with new up sector vector quark Fajfer et al. hep-ph/ factors of >1000 over SM not ruled out. 38 D Selection Require well reconstructed track in the muon spectrometer matched to a central track with p T >2 GeV, p > 3 GeV First select 0.96 < m( ) < 1.06 GeV 1.3 fb -1 Combine with a track in the same jet and select D candidate 1.4 < m ) < 2.4 GeV 39 Best Track Selection Large track multiplicity leads to several candidates per event. Select best track based on the D vertex 2, and distance between the track and the dimuon system M = 2 + R 2 All candidates false candidates correct candidate Candidate multiplicity MC 40 Background Suppression Isolation Flight length significance impact parameter significance Colinearity angle SS D s MC D + MC data sidebands 41 Results for Resonance Production Long Distance D Dimuon invariant mass n(D + ) = 115 +/- 33 > 4 sigma n(D s ) = 254 +/- 38 BF( D (1.41 +/ /- 0.46) x (PRL for 1.3 fb -1 result about to be released.) D significance > 5 Pion IP significance > fb -1 42 Next Step: Continuum Production By making a cut on m( ) around the , we clearly see the long distance component Now make a veto Large background enormous background Long Distance D n(D + ) = 115 +/- 33 > 4 sigma n(D s ) = 254 +/ fb -1 43 More Background Reduction Next step: continuum production. Much larger dimuon phase space requires more stringent requirements 44 Continuum Results n = 19 n(bkg) = 31 +/- 4 Short Distance D (PRL for 1.3 fb -1 result about to be released.) 1.3 fb -1 BF( D )