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2 Updated measurements of hadronic B decays at 1 0 CDF 2 n a J 5 2 ] x MichaelJ. Morello∗† e ScuolaNormaleSuperiorediPisaandINFNSezionediPisa - p E-mail: [email protected] e h [ The CDF experimentat the Tevatron pp¯ collider established that extensive and detailed explo- 1 ration of the b–quark dynamics is possible in hadron collisions, with results competitive and v supplementary to those from e+e colliders. This provides a rich, and highly rewarding pro- 7 − 6 gram that has currently reached full maturity. In the following I report some recent results on 2 hadronicdecays: the evidenceforthe charmlessannihilationdecaymodeB0 p +p , andthe 5 s → − . first reconstruction in hadron collisions of the suppressed decays B D( K+p )K and 1 − − − → → 0 B D( K+p )p . − − − 2 → → 1 : v i X r a The2011EurophysicsConferenceonHighEnergyPhysics,EPS-HEP2011, July21-27,2011 Grenoble,Rhône-Alpes,France Speaker. ∗ †OnbehalfoftheCDFCollaboration. (cid:13)c Copyrightownedbytheauthor(s)underthetermsoftheCreativeCommonsAttribution-NonCommercial-ShareAlikeLicence. http://pos.sissa.it/ UpdatedmeasurementsofhadronicBdecaysatCDF MichaelJ.Morello 1. Evidence forthe charmless annihilationdecay modeB0 p +p s − → Two-body non-leptonic charmless decays of b–hadrons are very widely studied processes in flavor physics. The variety of open channels involving similar final states provides useful exper- imental information to improve the accuracy of effective models of strong interaction dynamics. Somedecaysreceivecontributionsfromhigher-order(‘penguin’)transitions,andarethereforesen- sitivetothepossible presenceofnewphysicsininternal loops. TheB0 p +p andB0 K+K decaymodeshaveaspecial status, inthatallquarks inthe s − − → → final state are different from those in the initial state. This limits the possible diagrams that can contribute tothesedecaytopenguin-annihilation (PA)andW-exchange (E)topologies. Theyhave never been observed, andthebest upper limits comefrom [1,2]. Theseamplitudes are difficultto predictwithinthecurrentphenomenological models,andareoftenneglectedincalculations ofde- cayswheretheyarenottheonlycontributors,usinggenericargumentofsmallness. Thesediagrams may carry different CP-violating and CP-conserving phases with respect to leading diagrams; the lack of knowledge of their size therefore introduces unavoidable uncertainties in the conclusions drawnfromtheanalyses ofotherwell-studied decays, likeB0 p +p andB0 K+K . Amea- − s − → → surementofbranchingfractionofbothB0 p +p andB0 K+K wouldbeparticularlyuseful, s − − → → asitallowabetterdetermination ofthestrength ofPAandEamplitudes. CDF Run II Preliminary (cid:242) L dt = 6.11 fb-1 CDF Run II Preliminary (cid:242) L dt = 6.11 fb-1 22MeV/MeV/cc11550000 dtoattaal 22MeV/MeV/cc 110044 dtoattaal BB00sfifi KK++pK-- LB0s0bfifi Kp+-pK+- 0 0 B0fi K+p - 0 0 B0fi p +p - L 0bfi p+p - per 1per 1 BB0s0fifi pK++pK-- per 1per 1 110033 B0fi K+K- B0sfi p +p - ndidates ndidates 11000000 LLB0s0b0bfififi Kpp++-pKp+-- ndidates ndidates 110022 MCoumltibboindayt oBri adle bckagys CaCa B0fi K+K- CaCa 550000 B0sfi p +p - 1100 Multibody B decays Combinatorial bkg 11 55..00 55..22 55..44 55..66 55..88 55..00 55..22 55..44 55..66 55..88 IInnvvaarriiaannpptt pp --mmaassss [[GGeeVV//cc22]] IInnvvaarriiaannpptt pp --mmaassss [[GGeeVV//cc22]] Figure1: InvariantmassdistributionofreconstructedB0 h+h candidates(linearscaleontheleftand (s)→ ′− logarithmic scale on the right). The charged pion mass is assigned to both tracks. The sum of the fitted distributionsandtheindividualcomponentsofsignalandbackgroundareoverlaidonthedatadistribution. CDFrecentlysearchedforbothB0 p +p andB0 K+K ,usingadatasampleof6fb 1of s − − − → → integratedluminosity. Anextendedunbinnedlikelihoodfit,incorporatingkinematic(invariantmass and momenta) and particle identification (dE/dx) information, is used to determine the fraction of eachindividualB0 h+h (wherehisforapionorkaon)modeinthesample. Thefitprojection (s)→ ′− on the invariant pp -mass is reported in fig. 1. A 3.7s significant signal is observed for the B0 s → p +p mode, whilea deviation atthe 2s level from nosignal hypothesis isreported for the B0 − → K+K . The measured branching ratios are B(B0 p +p )=(0.57 0.15 0.10) 10 6 and − s − − → ± ± × 2 UpdatedmeasurementsofhadronicBdecaysatCDF MichaelJ.Morello B(B0 K+K )=(0.23 0.10 0.10) 10 6 [3]. A90%confidenceintervalfortheB0 K+K − − − → ± ± × → mode is also reported [0.05,0.46] 10 6 [3]. The result for the B0 p +p mode is consistent − s − × → with the previous upper limit (< 1.2 10 6 at 90% C.L.), based on a subsample of the current − × data [2] and it is in agreement with the very recent result from LHCb [4]. This agrees with the predictionsinRef.[5]withinthepQCDapproach. Itishigherthanmostotherpredictions[6,7,8]. Thepresent measurementofB(B0 K+K )supersedes theprevious limit[2]. Thecentral value − → isinagreement withotherexistingmeasurements [9,1,4],andwiththeoretical predictions [6,8]. 2. g from B DK decays → Conventionally, CPviolating observables are written interms of theangles a , b and g ofthe “Unitarity Triangle", obtained from one of theunitarity conditions ofthe CKMmatrix. While the resolution on a and b reached a good level of precision, the measurement of g is still limited by the smallness of the branching ratios involved in the processes. Among the various methods for the g measurement, those which make use of the tree-level B D0K decays have the smallest − − → theoretical uncertainties. Infactg appears astherelative weakphase between twoamplitudes, the favored b cu¯stransition oftheB D0K ,whoseamplitude isproportional toV V ,andthe − − cb us → → 0 color-suppressed b uc¯stransitionoftheB D K ,whoseamplitudeisproportionaltoV V . − − ub cs The interference be→tween D0 and D0, decayin→g into the same final state, leads to measurable CP- violating effects, from which g can be extracted. The effects can be also enhanced choosing the interfering amplitudes of the same order of magnitude. All methods require no tagging or time- dependent measurements, andmanyofthemonlyinvolve charged particlesinthefinalstate. CDF Run II Preliminary L = 7 fb-1 CDF Run II Preliminary L = 7 fb-1 int int 40 40 2c B- fi D0 p - fi [K+ p -] p - 2c B+ fi D0 p + fi [K- p +] p + V/ sup V/ sup e Data e Data M M er 14 30 BTBo-- fifital DD0s0suupp pK-- er 14 30 TBBo++ tfifial DD0s0suupp pK++ p B- fi K-p +p - p B+ fi K+p -p + ents 20 BB-- fifi DD00Kp --,, DD00fifi XX ents 20 BB++ fifi DD00Kp ++,, DD00fifi XX Ev B0 fi D0*- e+ n e Ev B0 fi D0*+ e- n e B- fi D0* p - B+ fi D0* p + Combinatorial background Combinatorial background 10 10 0 0 5.2 5.3 5.4 5.5 5.6 5.2 5.3 5.4 5.5 5.6 K+p -p - mass [GeV/c2] K-p +p + mass [GeV/c2] Figure2:InvariantmassdistributionsofB Dh forthesuppressedmode(bottommesonontheleftand ± ± → antibottomontheright). ThepionmassisassignedtothechargedtrackfromtheBcandidatedecayvertex. Theprojectionsofthelikelihoodfitareoverlaid. In a data sample of about 7 fb 1 CDF reports the first reconstruction in hadron collisions − of the suppressed decays B D( K+p )K and B D( K+p )p , which are the main − − − − − − → → → → ingredient of the the ADS method [10]. Also in this case an extended unbinned likelihood fit, 3 UpdatedmeasurementsofhadronicBdecaysatCDF MichaelJ.Morello incorporating kinematic (invariant mass) and particle identification (dE/dx) information, is used to determine the fraction of each individual modes. The fit projection on the invariant Kpp -mass is reported in fig. 2. CDF measures the following asymmetries: A (K)= 0.82 0.44(stat) ADS − ± ± 0.09(syst) andA (p )=0.13 0.25(stat) 0.02(syst) [11],andfortheratiosofdoublyCabibbo ADS ± ± suppressed mode to flavor eigenstate CDF finds R (K)=[22.0 8.6(stat) 2.6(syst)] 10 3 ADS − ± ± × andR (p )=[2.8 0.7(stat) 0.4(syst)] 10 3 [11]. Theresultsareinagreementwithexisting ADS − ± ± × measurements performed at¡ (4S)resonance [12]andveryrecentlyatLHCb[13]. 3. Conclusions CDFexperiment attheTevatronkeepsproviding excellentresultsintheexploration ofHeavy Flavor Physics, owing to CP-symmetric initial states in √s=1.96 TeV pp¯ collisions, large event samples collected by well-understood detector, and mature analysis techniques. In summary, this shortwrite-upreportsonthefirstevidenceforthecharmlessannihilationdecaymodeB0 p +p , s − → an updated upper limit for the B0 K+K mode, and on the first reconstruction in hadron colli- − → sionsofthesuppressed decaysB D( K+p )K andB D( K+p )p . − − − − − − → → → → References [1] K.Abeetal.(BelleCollaboration),ObservationofBDecaystoTwoKaons,Phys.Rev.Lett.98, 181804(2007)[hep-ex/0608049]. [2] T.Aaltonenetal.(CDFCollaboration),ObservationofNewCharmlessDecaysofBottomHadron, Phys.Rev.Lett.103,031801(2009)[hep-ex/0812.4271]. 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