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The anatomy of quark flavour observables in the flavour precision era

The anatomy of quark flavour observables in the flavour precision era. Fulvia De Fazio INFN- Bari. Portoroz 2013. Two topics Improving data precision and reducing theoretical uncertainties (FPE) would it be possible to understand from flavour observables

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The anatomy of quark flavour observables in the flavour precision era

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  1. The anatomy of quark flavour observables in the flavour precision era Fulvia De Fazio INFN- Bari Portoroz 2013 • Twotopics • Improving data precision and reducingtheoreticaluncertainties (FPE) • woulditbepossibletounderstandfromflavourobservables • if the lightest NP messangeris a new Z’ gaugeboson? • anexistingtension: exclusivesemileptonic b  c decays: • anomalousenhancementofmodeswith a t in the final state Based on works in collaborationwith A.J.Buras, J. Girrbach (Munich) & P. Biancofiore, P. Colangelo (Bari)

  2. Anatomy of Z’ with FCNC in the FPE A.J.Buras, J. Girrbach, FDF JHEP 1302 (2013) 116 • CKM parametershavebeendeterminedbymeansoftree-leveldecays • Non-perturbativeparameters are affectedbyverysmalluncertainties and fixed • Letusconsider the following case • Thereexists a newneutralgaugeboson Z’ mediatingtree-level FCNC processes • MZ’=1 TeVfordefiniteness • Couplingstoquarks are arbitrarywhilethosetoleptons are assumedalready • determinedbypurelyleptonicmodes Existing data constrain Z’ couplingstoquarks Fourpossiblescenariosforsuchcouplings can beconsidered Predictions on correlationsamongflavourobservablesprovide the path toidentifywhich, in any, ofthemisrealized in nature

  3. Anatomy of Z’ with FCNC in the FPE Analogousscenarios can beconsideredfor the quark pairs (bs) and (sd) Two cases |Vub| fixedto the exclusive (smaller) value |Vub| fixedto the inclusive (larger) value

  4. Anatomy of Z’ with FCNC in the FPE: the Bs system Weconsider the fourobservables: Mass difference in the B̅s–Bs system CP asymmetry in BsJ/ f CP asymmetry in Bsm+m- Theydependall on Imposing the experimentalconstraints: wefindallowedrangesfor the parameters s23 >0 & 0<d23<2p

  5. Bs system in LHS1 scenario A3 A4 Blueregions come from the constraint on Sf Red onesfrom the constraint on DMs Fourallowedoases: twobigones & twosmallones A2 A1 A1 Big Small Big Small Howtofind the optimaloasis?

  6. The decay Bsm+m- SMeffectivehamiltonian one master function Y0(xt) independent on the decayingmeson and on the leptonflavour Z’contributionmodifiesthisfunctionto: a newphase The variousscenariospredictdifferentresults Theoretically cleanobservable: phaseof the function S entering in the box diagram vanishes in SM the newphaseinvolved LHCb 1211.2674 SM

  7. The decay Bsm+m- A1 smalloases A3 exp 1 srange Excludes the smalloases Sm+m- >0 wouldchoose A1 Sm+m- <0 wouldchoose A3 No differencesfound in LHS2

  8. Anatomy of Z’ with FCNC in the FPE: the Bd system Weconsider the fourobservables: Mass difference in the B̅d–Bd system CP asymmetry in BdJ/ Ks CP asymmetry in Bdm+m- Theydependall on Imposing the experimentalconstraints: wefindallowedrangesfor the parameters s13 >0 & 0<d13<2p

  9. Bd system in LHS1 & LHS2 scenarios B3 B4 Blueregions SKs Red ones DMd B1 B2

  10. Bd system in LHS1 & LHS2 scenarios B2 B2 B4 B3 B4 B1 B3 B1 LHCb 1203.4493 SM • in the smalloases B(Bdm+m- ) is always larger than in SM • the signof Sm+m- distinguishes B1 from B3 and B2 from B4 Correlationbetween Sm+m- andB(Bdm+m- ): LHS1 vs LHS2 LHS1 : in B1 Sm+m- >0 & B(Bdm+m- ) > B(Bdm+m- ) SM in B3 Sm+m- <0 & B(Bdm+m- ) < B(Bdm+m- ) SM LHS2 : in B1 Sm+m- >0 & B(Bdm+m- ) < B(Bdm+m- ) SM in B3 Sm+m- <0 & B(Bdm+m- ) > B(Bdm+m- ) SM

  11. RHS1 & RHS2 scenarios Means Z’ withexclusively RH couplingstoquarks QCD isparityconserving hadronicmatrixelementsofoperatorswith RH currents & QCD correctionsremainunchanged DF=2 constraintsappear the sameas in LHS scenarios  the oasesremain the same DF=1 observables: decaystomuonsgovernedby the function Y Thereis a changeofsignof NP contributions in a givenoasis

  12. RHS1 & RHS2 scenarios Bs system LHS RHS Sm+m- >0 wouldchoose A1 Sm+m- <0 wouldchoose A3 Sm+m- >0 wouldchoose A3 Sm+m- <0 wouldchoose A1 Bd system Correlationbetween Sm+m- andB(Bdm+m- ): LHS1 vs LHS2 LHS1 : in B1 Sm+m- >0 & B(Bdm+m- ) > B(Bdm+m- ) SM in B3 Sm+m- <0 & B(Bdm+m- ) < B(Bdm+m- ) SM LHS2 : in B1 Sm+m- >0 & B(Bdm+m- ) < B(Bdm+m- ) SM in B3 Sm+m- <0 & B(Bdm+m- ) > B(Bdm+m- ) SM Oppositesigns in RHS scenarios On the basisoftheseobservablesitwouldnotbepossibletoknowwhether LHS in oases A1 (B1) isrealized or RHS in oases A3 (B3)

  13. LRS1 & LRS2 scenarios Bs system Bd system Maindifferencewithrespectto the previouscases: No NP contributiontoBd,sm+m-  We cannot rely on this observable to identify the right oases ALRS1 & ALRS2 scenarios Similarto LHS scenario, but NP effectsmuchsmaller

  14. Can we exploit other observables? b  s l+l- SM NP operators coefficients

  15. b  s l+l- W. Altmannshofer & D. Straub, JHEP 1208 (2012) 121 Exploitingpresent data constraints can beobtained: A3 A1 A1 Oasis A1 excluded in LRS

  16. b  s l+l- Blackregions are excluded due to the constraint on C10’ An enhancementof B(Bsm+m- ) withrespectto SM isexcluded ONLY in RHS!! Possibilitytodifferentiatebetween LHS and RHS scenarios, butonlyif B(Bsm+m- )> B(Bsm+m- )SM

  17. b  s n̅n SM EXP Altmannshoferet al. JHEP 04 (2009) 022 Sensitive observables excludedby b  s l+l- Cleardistinctionbetween LHS and RHS

  18. B  D(*) t n̅t BaBarmeasurements: BaBar, PRL 109 (2012) 101802 SM • BaBarquotes a 3.4 sdeviationfrom SM predictions • isthisrelatedto the enhancementof B(B tnt) ? …but… SM predictionfor |Vub|=0.0035  0.0005

  19. B  D(*) t n̅t • Mostnaturalexplanation: newscalarswithcouplingstoleptonsproportionaltotheir mass • wouldexplain the enhancementoftmodes • wouldenhancebothsemileptonic and purelyleptonicmodes The simplestofsuchmodels (2HDM) hasbeenexcludedbyBaBar: No possibilitytosimultaneouslyreproduce R(D) and R(D*) • Alternative explanationsusingseveralvariantsofeffectivehamiltonian • S. Fajferet al, PRD 85 (2012) 094025; PRL 109 (2012) 161801 • A. Crivellinet al., PRD 86 (2012) 054014 • A. Dattaet al., PRD 86 (2012) 034027 • A. Celiset al., JHEP 1301 (2013) 054 • D. Choudhuryet al, PRD 86 (2012) 114037

  20. B  D(*) t n̅t P. Biancofiore, P. Colangelo, FDF 1302.1042, PRD 87 (2013) 074010 • A differentstrategy: • consider a NP scenario thatenhancessemileptonicmodesbutnotleptonicones • predictsimilareffects in otheranalogousmodes SM NP newcomplexcoupling: eTm,e=0, eTt≠ 0 Charmedmeson  |eT|2  Re(eT) • A simlarstrategy in • M. Tanaka & R. Watanabe 1212.1878

  21. B  D(*) t n̅t Including a newtensoroperator in Heff : isitpossibletoreproduceboth R(D) and R(D*)? Big circle: R(D) constraint overlapregion: Smallcircle: R(D*) constraint varyingeT in thisrangepredictions forseveralobservables can begained

  22. B  D(*) t n̅t: whichobservables are the most sensitive ? Comparisonwith the latestBaBarresults: BaBarCollab. 1303.0571 include NP The spectradG/dq2cannotdistinguish the SM from the NP case

  23. B  D*t n̅t Forward-Backwardasymmetry angle between the chargedlepton and the D* in the leptonpairrest-frame The SM predicts a zero at q2 6.15 GeV2 In NP the zero isshiftedto q2 [8.1,9.3] GeV2 • Uncertainty in the SM predictionis due to 1/mQcorrections • and to the parametersof the IW functionfittedby Belle • NP includesuncertainty on eT

  24. B  D** t n̅t D**=positive parityexcitedcharmedmesons Twodoublets: (D(s)0*,D(s)1’) withJP=(0+,1+) and (D(s)1,D(s)2*) withJP=(1+,2+) Formfactorsforsemileptonic B decaystothesestates can beexpressed in termsof universalfunctionsanalogousto the IW B  (D(s)0*,D(s)1’) t1/2(w) B  (D(s)1,D(s)2*) t3/2(w) Weconsideragainratios in which the dependence on the modelfor the tfunctionsmostlydrops out

  25. B  D** t n̅t Orange= non strange Bluecircle= SM Green=strange Triangle= SM The inclusionof the tensoroperatorproduces a sizableincrease in the ratios Forward-backwardasymmetries shift in the position of the zero the zero disappears

  26. summary Studyingcorrelationsbetweenflavourobservablesmayleadusto select the right scenario (ifany) for Z’ couplingstoquarksfor MZ’=1 TeV Largermasses (>5 TeV) havenegligible impact on the observablesconsidered • The mostconstrained system isthatofBs • importantroleisplayedby Sf and B(Bsm+m-) • highest sensitivity to RHC is that of b  s l+l- and b  s n̅n Anomalousenhancementof R(D(*)) couldbeexplainedintroducing a newtensoroperator in the effectivehamiltonian. Differentialdistributions help to discriminate this scenario from SM Largeeffectsforseen in B  D** t n̅t

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