The CDF and D\O\ experiments at the Tevatron $p\bar{p}$ collider established
that extensive and detailed exploration of the $b$--quark dynamics is possible
in hadron collisions, with results competitive and supplementary to those from
$e^+e^-$ colliders. This provides a rich, and highly rewarding program that is
currently reaching full maturity. I report a few recent world-leading results
on rare decays, CP-violation in $B^0_s$ mixing, $b\to s$ penguin decays, and
charm physics.Comment: 5 pages, 1 figure, proceedings for IFAE2011. To be published in the
  Nuovo Cimento C - Colloquia on Physic

Morello, Michael Joseph

English

arXiv

The CDF and D0 experiments at the Tevatron p{bar p} collider established that extensive and detailed exploration of the b-quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from e{sup +}e{sup -} colliders. This provides a rich, and highly rewarding program that is currently reaching full maturity. I report a few recent world-leading results on rare decays, CP-violation in B{sub s}{sup 0} mixing, b {yields} s penguin decays, and charm physics

UNT Digital Library

IL NUOVO CIMENTO Vol. ?, N. ? ?B Physics at the TeVatronM.J. Morello(1)(∗)(1) University of Pisa and INFN of Pisa - Largo Bruno Pontecorvo 3, 56127 Pisa, ItalySummary. — The CDF and DØ experiments at the Tevatron pp̄ collider estab-lished that extensive and detailed exploration of the b–quark dynamics is possible inhadron collisions, with results competitive and supplementary to those from e+e−colliders. This provides a rich, and highly rewarding program that is currentlyreaching full maturity. I report a few recent world-leading results on rare decays,CP-violation in B0s mixing, b → s penguin decays, and charm physics.PACS 13.20.He – Decays of bottom hadrons.PACS 13.25.Ft – Decays of charmed hadrons.PACS 13.30.Eg – Hadronic decays.1. – IntroductionPrecise results from the successful B factory experiments disfavor large contribu-tions from non-standard model (SM) physics in tree-dominated bottom meson decays.Agreement with the SM within theory uncertainties is also manifest in higher-order pro-cesses, such as K0–K̄0 or B0–B̄0 flavor mixing. The emerging picture confirms theCabibbo-Kobayashi-Maskawa (CKM) framework as the leading pattern of flavor dynam-ics. Non-SM contributions, if any, are small corrections, or appear well beyond the TeVscale (and the LHC reach), or have an unnatural, highly fine-tuned flavor structure thatescaped all experimental tests to date. The last chances to avoid such a disappointingimpasse include the extensive study of the physics of the bottom-strange mesons, stillfairly unexplored, along with a few rare B0 decays, not fully probed at the B factoriesbecause of limited event statistics.CDF and DØ experiments at the Tevatron are currently leading the exploration ofthis physics, owing to CP-symmetric initial states in√s = 1.96 TeV pp̄ collisions, largeevent samples collected by well-understood detectors, and mature analysis techniques.CDF and DØ have currently collected more than 8 fb−1 of physics-quality data. Thesample size will reach 10 fb−1 in October 2011.(∗) for the CDF and DØ Collaborationsc© Società Italiana di Fisica 1FERMILAB-CONF-11-512-PPDOperated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy2 M.J. MORELLOIn the following I report some recent, world-leading results, selected among thosemore sensitive to the presence of non-SM particles or couplings. Branching fractionsindicate CP-averages, charge-conjugate decays are implied everywhere.2. – Rare B → µ+µ− and B → hµ+µ− decaysDecays mediated by flavor changing neutral currents, such as B0(s) → µ+µ− or B →hµ+µ− are highly suppressed in the SM because they occur only through higher orderloop diagrams. Their phenomenology provide enhanced sensitivity to a broad class ofnon-SM contributions.The B0(s) → µ+µ− rate is proportional to the CKM matrix element |Vtd|2(|Vts|2),and is further suppressed by helicity factors. The SM expectations for these branchingfractions are O(10−9), ten times smaller than the current experimental sensitivity. Anobservation of these decays at the Tevatron would unambiguously indicate physics beyondthe SM. On the other hand, improved exclusion-limits strongly constrain the availablespace of parameters of several models of supersymmetry (SUSY). The latest CDF searchfor B0(s) → µ+µ− decays uses 3.7 fb−1. The resulting 90 (95)% CL upper-limits areB(B0s → µ+µ−) < 3.6(4.3) × 10−8 and B(B0 → µ+µ−) < 6.0(7.6) × 10−9 [1]. Theseresults are the most stringent currently available and reduce significantly the allowedparameter space for a broad range of SUSY models. An update of this analysis withapproximately double sized sample will further improve them soon. The CDF expected95% CL upper-limit is B(B0s → µ+µ−) < 2×10−8 [2], on a data sample corresponding toapproximatively 7 fb−1. DØ performed a similar analysis using a data sample of about6.1 fb−1. The resulting 90 (95)% CL upper-limit is B(B0s → µ+µ−) < 4.2(5.1)×10−8 [3].CDF also updated the analysis of B0 → K∗(892)0µ+µ−, B+ → K+µ+µ−, andB0s → φµ+µ− decays to 4.4 fb−1of data [4]. These are suppressed in the SM (B ≈10−6), with amplitudes dominated by penguin and box b → s transitions. Despitethe presence of final-state hadrons, accurate predictions greatly sensitive to non-SMcontributions are possible for relative quantities based on angular-distributions of fi-nal state particles [5]. Prominent signals of 120 ± 16 B+ → K+µ+µ− and 101 ± 12B0 → K∗0µ+µ− events are observed. The absolute branching fractions, measured usingthe resonant decays as a reference, are [0.38 ± 0.05 (stat .) ± 0.03 (syst .)] × 10−6 and[1.06 ± 0.14 (stat .) ± 0.09 (syst .)] × 10−6, respectively, consistent and competitive withprevious determinations [6]. In addition, 27± 6 B0s → φµ+µ− events are reconstructed,corresponding to the first observation of this decay, with a significance in excess of 6σ.The branching ratio, [1.44 ± 0.33 (stat .) ± 0.46 (syst .)] × 10−5, is consistent with theo-retical prediction, and corresponds to the rarest B0s decay ever observed to date.3. – Measurement of the B0s mixing phaseNon-SM contributions have not yet been excluded in B0s -B0s mixing. Their magnitudeis constrained to be small by the precise determination of the frequency [7]. However,knowledge of only the frequency leaves possible non-SM contributions to the uncon-strained (CP-violating) mixing phase. The time evolution of flavor-tagged B0s → J/ψφdecays allows a determination of this phase largely free from theoretical uncertainties.These decays probe the phase-difference between the mixing and the b̄→ c̄cs̄ quark-leveltransition, βs = βSMs + βNPs , which equals βSMs = arg(−VtsV ∗tb/VcsV ∗cb) ≈ 0.02 in theSM and is extremely sensitive to non-SM physics in the mixing. A non-SM contributionB PHYSICS AT THE TEVATRON 3(βNPs ) would also enter φs = φSMs − 2βNPs , which is the phase difference between directdecay and decay via mixing into final states common to B0s and B0s, and is also tiny inthe SM: φSMs = arg(−M12/Γ12) ≈ 0.004. Because the SM values for βs and φs cannot beresolved with the precision of current experiments, the following approximation is used:φs ≈ −2βNPs ≈ −2βs, which holds in case of sizable non-SM contributions. Note thatthe phase φs also modifies the decay-width difference between light and heavy states,∆Γ = ΓL − ΓH = 2|Γ12| cos(φs), which enters in the B0s → J/ψφ amplitude and equals∆ΓSM ≈ 2|Γ12| = 0.086± 0.025 ps−1 in the SM [8].CDF and DØ updated the measurement of the time-evolution of flavor-tagged B0s →J/ψφ decays respectively to a sample of 5.2 fb−1 and 6.1 fb−1 [9, 10]. With phase floating (rad)                 sβ-1 0 1)                  -1 (psΓ∆-0.6-0.4-0.20.00.20.40.6-1CDF Run II Preliminary        L = 5.2 fb95% CL68% CLSM predictionFig. 1. – Confidence region in the (βs,∆Γ) plane for CDF (left pannel), in the (φs,∆Γ) planefor DØ (right pannel).the resulting allowed regions in the (βs, ∆Γs) plane are shown in Fig. 1. They are greatlyreduced with respect to the previous measurements [11]. CDF is fairly consistent withthe SM, at 0.8σ level with no external constraints. DØ reports a similar result, butusing external inputs for strong phases δ1 = −0.42 ± 0.18 and δ2 = 3.01 ± 0.14 [6] and∆Ms = 17.77± 0.12 ps−1 [7].The decay B0s → J/ψφ has a mixture of the CP-even and -odd components in thefinal state and an angular analysis is needed to separate them. A sufficiently copiousB0s → J/ψf0(980) signal with f0(980) → π+π−, and tagged B0s production flavor can beused to measure βs without the need of an angular analysis as J/ψf0(980) is a pure CP-odd final state. Further interest in the decay B0s → J/ψf0(980) arises from the fact thatit could contribute to an S-wave component in the B0s → J/ψK+K− decay if f0(980)decays to K+K−. CDF recently confirmed the observation of the B0s → J/ψf0(980)decay from the LHCb and Belle experiments [12]. At present the observed signal isthe world’s largest and the measurement of the ratio of branching fractions betweenB0s → J/ψf0(980) and B0s → J/ψφ decays 0.257± 0.020 (stat .)± 0.014 (syst .) [13] is thethe most precise. Using the world average B0s → J/ψφ branching fraction [6] this can beconverted into the product of branching fractions of B(B0s → J/ψf0(980))B(f0(980) →π+π−) = (1.63±0.12±0.09±0.50)×10−4 [13] where the first uncertainty is statistical, thesecond is systematic and the third one is due to the uncertainty on branching fraction ofnormalization channels. The measurement presented here agrees well with the previousmeasurements of this quantity. CDF reports also the first determination of the lifetimeof this decay mode τ = 1.70+0.12−0.11 (stat .)± 0.03 (syst .) [13].An alternative way of accessing φs is through the measurement of the asymmetry4 M.J. MORELLOAbsl defined as Absl ≡ N++b−N−−bN++b+N−−b, where N++b and N−−b represent the number of eventscontaining two b hadrons decaying semileptonically and producing two positive or twonegative muons, respectively. Measurements of Absl or φq that differ significantly fromthe SM expectations would indicate the presence of new physics.DØ analysed a data sample corresponding to an integrated luminosity of 6.1 fb−1 andmeasured the like-sign dimuon charge asymmetry of semileptonic b-hadron decays: Absl =−0.00957±0.00251 (stat)±0.00146 (syst) [14], which is in disagreement with the predic-tion of the standard model by 3.2 standard deviations, as reported in fig. 1 by the band,which is a 68% CL contour.4. – γ from B → DK decaysConventionally, CP violating observables are written in terms of the angles α, βand γ of the “Unitarity Triangle”, obtained from one of the unitarity conditions of theCKM matrix. While the resolution on α and β reached a good level of precision, themeasurement of γ is still limited by the smallness of the branching ratios involved in theprocesses. Among the various methods for the γ measurement, those which make use ofthe tree-level B− → D0K− decays have the smallest theoretical uncertainties [15, 16, 17].In fact γ appears as the relative weak phase between two amplitudes, the favored b→ cūstransition of the B− → D0K−, whose amplitude is proportional to VcbVus, and the color-suppressed b → uc̄s transition of the B− → D0K−, whose amplitude is proportional toVubVcs. The interference between D0 and D0, decaying into the same final state, leadsto measurable CP-violating effects, from which γ can be extracted. The effects canbe also enhanced choosing the interfering amplitudes of the same order of magnitude.All methods require no tagging or time-dependent measurements, and many of themonly involve charged particles in the final state. CDF reports the first results in hadroncollisions for the ADS [15] and GLW [16] methods.In a data sample of about 5 fb−1 CDFmeasures the following asymmetries: AADS(K) =−0.63±0.40(stat)±0.23(syst) and AADS(π) = 0.22±0.18(stat)±0.06(syst). [18]. For theratios of doubly Cabibbo suppressed mode to flavor eigenstate CDF finds RADS(K) =[22.5± 8.4(stat)± 7.9(syst)] ·10−3 and RADS(π) = [4.1± 0.8(stat)± 0.4(syst)] ·10−3 [18].These quantities are measured for the first time in hadron collisions. The results are inagreement with existing measurements performed at Υ(4S) resonance [19]. The resultson GLW method from CDF can be found in Ref. [20].5. – Charm PhysicsWhile investigations of the K and B systems have and will continue to play a rolein the understanding of flavor physics and CP violation, the D mesons sector have yetprobed with a sufficient precision to explore the range of SM predictions. Since charmquark is the only up-type charged quark accessible to experiment though the D mesons,it provides the unique opportunity to probe flavor physics in this sector that is com-plementary to the one of down-type quarks. Examples of clean channels sensitive topossible sources of CP violation in the charm system are the singly-Cabibbo suppressedtransitions such as D0 → π+π− and D0 → K+K−. Contribution to these decays from“penguin” amplitudes are negligible in the SM, thus the presence of new exotic parti-cles may enhance the size of CP violation with respect to the SM expectation. Anyasymmetry significantly larger than a few times 0.1% may unambiguously indicate NPB PHYSICS AT THE TEVATRON 5contributions.CDF recently measured the time-integrated CP asymmetry in the D0 → π+π− andD0 → K+K− decays using 5.94 fb−1 of data collected by the displaced track trigger. Thefinal results, which are the most precise up to date, are ACP (D0 → π+π−) = [+0.22±0.24 (stat .) ± 0.11 (syst .)]% and ACP (D0 → K+K−) =[−0.24 ± 0.22 (stat .) ±0.10 (syst .)]% [21]. They are consistent with CP conservation and also with the SMpredictions. As expressed by Eq. 3 of Ref. [21] the ACP (D0 → h+h−) measurementdescribes a straight line in the plane (AindCP , AdirCP ) with angular coefficient given by 〈t〉/τ ,being t the measured proper decay time of the D0 candidates and τ the lifetime of theD0 meson. Because of a threshold on the impact parameter of tracks, imposed at triggerlevel, the CDF sample ofD0 → π+π− (D0 → K+K−) decays is enriched in higher-valuedproper decay time candidates with a mean value of 2.40(2.65)± 0.03 (stat .+ syst .) timesthe D0 lifetime, as measured from a fit to the proper time distribution. Due to theirunbiased acceptance in charm decay time, B factories samples have instead 〈t〉 ≈ τ .Hence, the combination of the three measurements allow to constrain independentlyboth AdirCP and AindCP [21].REFERENCES[1] CDF Collaboration, Note 9892.[2] D. Kong (for the CDF Collaboration), Talk at BEAUTY 2011, Amsterdam.[3] V. Abazov et al. (DØ Collaboration), Phys. Lett. B, 693 (2010) 539.[4] T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett., 106 (2011) 161801.[5] A. Ali et al., Phys. Rev. D, 61 (2000) 074024.[6] K. Nakamura et al., J. Phys. G, 37 (2010) 075021.[7] A. Abulencia et al. (CDF Collaboration), Phys. Rev. Lett., 97 (2006) 242003.[8] A. Lenz and U. Nierste, J. High Energy Phys, 0706 (2007) 072.[9] CDF Collaboration, Note 10206.[10] DØ Collaboration, Note 6098.[11] T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett., 100 (2008) 161802;V. M. Abazov et al. (DØ Collaboration), Phys. Rev. Lett., 101 (2008) 241801.[12] R. Aaij et al. (LHCb Collaboration),Phys. Lett. B, 698 (2011) 115; J. Li et al. (BelleCollaboration),Phys. Rev. Lett., 106 (2011) 121802.[13] CDF Collaboration, arXiv:1106.3682 [hep-ex] preprint (2011).[14] V. M. Abazov et al. (DØ Collaboration), Phys. Rev. D, 82 (2010) 032001.[15] M. Gronau and D. Wyler, Phys. Lett. B, 265 (1991) 172.[16] D. Atwood, I. Dunietz and A. Soni, Phys. Rev. Lett., 78 (1997) 3257.[17] A. Giri, Y. Grossman, A. Soffer and J. Zupan, Phys. Rev. Lett., 68 (2003) 054018.[18] CDF Collaboration, Note 10309.[19] Y. Horii et al. (Belle Collaboration), Phys. Rev. Lett., 106 (2011) 231803;P. del Amo Sanchez et al. (BaBar Collaboration), Phys. Rev. D, 82 (2010) 072006.[20] T. Aaltonen et al. (CDF Collaboration), Phys. Rev., D81 (2010) 031105.[21] CDF Collaboration, Note 10296.

B Physics at the TeVatron

The CDF and DØ experiments at the Tevatron p¯p collider established that extensive and detailed exploration of the b-quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from e+e−

colliders. This provides a rich, and highly rewarding program that is currently reaching full maturity. I report a few recent world-leading results on rare decays, 

CP-violation in B0s mixing, b → s penguin decays, and charm physics

Morello, M. J.

Scientific Open-access Literature Archive and Repository

DOI 10.1393/ncc/i2011-11018-5Colloquia: IFAE 2011IL NUOVO CIMENTO Vol. 34 C, N. 6 Novembre-Dicembre 2011B physics at the TevatronM. J. Morello for the CDF and DØ CollaborationsUniversita` di Pisa and INFN, Sezione di Pisa - Largo B. Pontecorvo 3, 56127 Pisa, Italy(ricevuto il 29 Luglio 2011; pubblicato online il 25 Ottobre 2011)Summary. — The CDF and DØ experiments at the Tevatron pp¯ collider estab-lished that extensive and detailed exploration of the b-quark dynamics is possible inhadron collisions, with results competitive and supplementary to those from e+e−colliders. This provides a rich, and highly rewarding program that is currentlyreaching full maturity. I report a few recent world-leading results on rare decays,CP -violation in B0s mixing, b→ s penguin decays, and charm physics.PACS 13.20.He – Decays of bottom mesons.PACS 13.25.Ft – Decays of charmed mesons.PACS 13.30.Eg – Hadronic decays.1. – IntroductionPrecise results from the successful B factory experiments disfavor large contributionsfrom non-standard model (SM) physics in tree-dominated bottom meson decays. Agree-ment with the SM within theory uncertainties is also manifest in higher-order processes,such as K0-K¯0 or B0-B¯0 flavor mixing. The emerging picture confirms the Cabibbo-Kobayashi-Maskawa (CKM) framework as the leading pattern of flavor dynamics. Non-SM contributions, if any, are small corrections, or appear well beyond the TeV scale (andthe LHC reach), or have an unnatural, highly fine-tuned flavor structure that escapedall experimental tests to date. The last chances to avoid such a disappointing impasseinclude the extensive study of the physics of the bottom-strange mesons, still fairly un-explored, along with a few rare B0 decays, not fully probed at the B factories becauseof limited event statistics.CDF and DØ experiments at the Tevatron are currently leading the exploration ofthis physics, owing to CP -symmetric initial states in√s = 1.96TeV pp¯ collisions, largeevent samples collected by well-understood detectors, and mature analysis techniques.CDF and DØ have currently collected more than 8 fb−1 of physics-quality data. Thesample size will reach 10 fb−1 in October 2011.In the following I report some recent, world-leading results, selected among thosemore sensitive to the presence of non-SM particles or couplings. Branching fractionsindicate CP -averages, charge-conjugate decays are implied everywhere.c© Societa` Italiana di Fisica 8182 M. J. MORELLO for the CDF AND DØ COLLABORATIONS2. – Rare B → μ+μ− and B → hμ+μ− decaysDecays mediated by flavor changing neutral currents, such as B0(s) → μ+μ− or B →hμ+μ− are highly suppressed in the SM because they occur only through higher-orderloop diagrams. Their phenomenology provide enhanced sensitivity to a broad class ofnon-SM contributions.The B0(s) → μ+μ− rate is proportional to the CKM matrix element |Vtd|2(|Vts|2),and is further suppressed by helicity factors. The SM expectations for these branchingfractions are O(10−9), ten times smaller than the current experimental sensitivity. Anobservation of these decays at the Tevatron would unambiguously indicate physics beyondthe SM. On the other hand, improved exclusion-limits strongly constrain the availablespace of parameters of several models of supersymmetry (SUSY). The latest CDF searchfor B0(s) → μ+μ− decays uses 3.7 fb−1. The resulting 90 (95)% CL upper limits areB(B0s → μ+μ−) < 3.6(4.3) × 10−8 and B(B0 → μ+μ−) < 6.0(7.6) × 10−9 [1]. Theseresults are the most stringent currently available and reduce significantly the allowedparameter space for a broad range of SUSY models. An update of this analysis withapproximately double-sized sample will further improve them soon. The CDF expected95% CL upper limit is B(B0s → μ+μ−) < 2×10−8 [2], on a data sample corresponding toapproximatively 7 fb−1. DØ performed a similar analysis using a data sample of about6.1 fb−1. The resulting 90 (95)% CL upper limit is B(B0s → μ+μ−) < 4.2(5.1)×10−8 [3].CDF also updated the analysis of B0 → K∗(892)0μ+μ−, B+ → K+μ+μ−, andB0s → φμ+μ− decays to 4.4 fb−1 of data [4]. These are suppressed in the SM (B ≈ 10−6),with amplitudes dominated by penguin and box b → s transitions. Despite thepresence of final-state hadrons, accurate predictions greatly sensitive to non-SM con-tributions are possible for relative quantities based on angular-distributions of finalstate particles [5]. Prominent signals of 120 ± 16 B+ → K+μ+μ− and 101 ± 12B0 → K∗0μ+μ− events are observed. The absolute branching fractions, measured usingthe resonant decays as a reference, are [0.38 ± 0.05 (stat.) ± 0.03 (syst.)] × 10−6 and[1.06 ± 0.14 (stat.) ± 0.09 (syst.)] × 10−6, respectively, consistent and competitive withprevious determinations [6]. In addition, 27± 6 B0s → φμ+μ− events are reconstructed,corresponding to the first observation of this decay, with a significance in excess of 6σ.The branching ratio, [1.44±0.33 (stat.)±0.46 (syst.)]×10−5, is consistent with theoreticalprediction, and corresponds to the rarest B0s decay ever observed to date.3. – Measurement of the B0s mixing phaseNon-SM contributions have not yet been excluded in B0s -B0s mixing. Their magnitudeis constrained to be small by the precise determination of the frequency [7]. However,knowledge of only the frequency leaves possible non-SM contributions to the uncon-strained (CP -violating) mixing phase. The time evolution of flavor-tagged B0s → J/ψφdecays allows a determination of this phase largely free from theoretical uncertainties.These decays probe the phase-difference between the mixing and the b¯ → c¯cs¯ quark-leveltransition, βs = βSMs + βNPs , which equals βSMs = arg(−VtsV ∗tb/VcsV ∗cb) ≈ 0.02 in theSM and is extremely sensitive to non-SM physics in the mixing. A non-SM contribution(βNPs ) would also enter φs = φSMs − 2βNPs , which is the phase difference between directdecay and decay via mixing into final states common to B0s and B0s, and is also tiny inthe SM: φSMs = arg(−M12/Γ12) ≈ 0.004. Because the SM values for βs and φs cannot beresolved with the precision of current experiments, the following approximation is used:B PHYSICS AT THE TEVATRON 83 (rad)                 sβ-1 0 1)                  -1 (psΓΔ-0.6-0.4-0.20.00.20.40.6-1CDF Run II Preliminary        L = 5.2 fb95% CL68% CLSM predictionFig. 1. – Confidence region in the (βs,ΔΓ)-plane for CDF (left panel), in the (φs,ΔΓ)-plane forDØ (right panel).φs ≈ −2βNPs ≈ −2βs, which holds in case of sizable non-SM contributions. Note thatthe phase φs also modifies the decay-width difference between light and heavy states,ΔΓ = ΓL − ΓH = 2|Γ12| cos(φs), which enters in the B0s → J/ψφ amplitude and equalsΔΓSM ≈ 2|Γ12| = 0.086± 0.025 ps−1 in the SM [8].CDF and DØ updated the measurement of the time-evolution of flavor-tagged B0s →J/ψφ decays respectively to a sample of 5.2 fb−1 and 6.1 fb−1 [9,10]. With phase floatingthe resulting allowed regions in the (βs,ΔΓs)-plane are shown in fig. 1. They are greatlyreduced with respect to the previous measurements [11]. CDF is fairly consistent withthe SM, at 0.8σ level with no external constraints. DØ reports a similar result, butusing external inputs for strong phases δ1 = −0.42 ± 0.18 and δ2 = 3.01 ± 0.14 [6] andΔMs = 17.77± 0.12 ps−1 [7].The decay B0s → J/ψφ has a mixture of the CP -even and -odd components in thefinal state and an angular analysis is needed to separate them. A sufficiently copiousB0s → J/ψf0(980) signal with f0(980) → π+π−, and tagged B0s production flavor can beused to measure βs without the need of an angular analysis as J/ψf0(980) is a pure CP -odd final state. Further interest in the decay B0s → J/ψf0(980) arises from the fact thatit could contribute to an S-wave component in the B0s → J/ψK+K− decay if f0(980)decays to K+K−. CDF recently confirmed the observation of the B0s → J/ψf0(980)decay from the LHCb and Belle experiments [12]. At present the observed signal isthe world’s largest and the measurement of the ratio of branching fractions betweenB0s → J/ψf0(980) and B0s → J/ψφ decays 0.257± 0.020 (stat.)± 0.014 (syst.) [13] is thethe most precise. Using the world average B0s → J/ψφ branching fraction [6] this can beconverted into the product of branching fractions of B(B0s → J/ψf0(980))B(f0(980) →π+π−) = (1.63±0.12±0.09±0.50)×10−4 [13] where the first uncertainty is statistical, thesecond is systematic and the third one is due to the uncertainty on branching fraction ofnormalization channels. The measurement presented here agrees well with the previousmeasurements of this quantity. CDF reports also the first determination of the lifetimeof this decay mode τ = 1.70+0.12−0.11 (stat.)± 0.03 (syst.) [13].An alternative way of accessing φs is through the measurement of the asymmetryAbsl defined as Absl ≡ N++b−N−−bN++b+N−−b, where N++b and N−−b represent the number of eventscontaining two b hadrons decaying semileptonically and producing two positive or twonegative muons, respectively. Measurements of Absl or φq that differ significantly fromthe SM expectations would indicate the presence of new physics.84 M. J. MORELLO for the CDF AND DØ COLLABORATIONSDØ analysed a data sample corresponding to an integrated luminosity of 6.1 fb−1and measured the like-sign dimuon charge asymmetry of semileptonic b-hadron decays:Absl = −0.00957 ± 0.00251 (stat.) ± 0.00146 (syst.) [14], which is in disagreement withthe prediction of the standard model by 3.2 standard deviations, as reported in fig. 1 bythe band, which is a 68% CL contour.4. – γ from B → DK decaysConventionally, CP -violating observables are written in terms of the angles α, βand γ of the “Unitarity Triangle”, obtained from one of the unitarity conditions of theCKM matrix. While the resolution on α and β reached a good level of precision, themeasurement of γ is still limited by the smallness of the branching ratios involved in theprocesses. Among the various methods for the γ measurement, those which make use ofthe tree-level B− → D0K− decays have the smallest theoretical uncertainties [15-17]. Infact γ appears as the relative weak phase between two amplitudes, the favored b → cu¯stransition of the B− → D0K−, whose amplitude is proportional to VcbVus, and the color-suppressed b → uc¯s transition of the B− → D0K−, whose amplitude is proportional toVubVcs. The interference between D0 and D0, decaying into the same final state, leadsto measurable CP -violating effects, from which γ can be extracted. The effects canbe also enhanced choosing the interfering amplitudes of the same order of magnitude.All methods require no tagging or time-dependent measurements, and many of themonly involve charged particles in the final state. CDF reports the first results in hadroncollisions for the ADS [15] and GLW [16] methods.In a data sample of about 5 fb−1 CDF measures the following asymmetries:AADS(K) =−0.63±0.40 (stat.)±0.23 (syst.) and AADS(π) = 0.22±0.18 (stat.)±0.06 (syst.) [18]. Forthe ratios of doubly Cabibbo suppressed mode to flavor eigenstate CDF finds RADS(K) =[22.5±8.4 (stat.)±7.9 (syst.)]·10−3 and RADS(π) = [4.1±0.8 (stat.)±0.4 (syst.)]·10−3 [18].These quantities are measured for the first time in hadron collisions. The results are inagreement with existing measurements performed at Υ(4S) resonance [19]. The resultson GLW method from CDF can be found in ref. [20].5. – Charm physicsWhile investigations of the K and B systems have and will continue to play a rolein the understanding of flavor physics and CP violation, the D mesons sector haveyet probed with a sufficient precision to explore the range of SM predictions. Sincecharm quark is the only up-type charged quark accessible to experiment though the Dmesons, it provides the unique opportunity to probe flavor physics in this sector that iscomplementary to the one of down-type quarks. Examples of clean channels sensitive topossible sources of CP violation in the charm system are the singly-Cabibbo suppressedtransitions such as D0 → π+π− and D0 → K+K−. Contributions to these decaysfrom “penguin” amplitudes are negligible in the SM, thus the presence of new exoticparticles may enhance the size of CP violation with respect to the SM expectation. Anyasymmetry significantly larger than a few times 0.1% may unambiguously indicate NPcontributions.CDF recently measured the time-integrated CP asymmetry in the D0 → π+π− andD0 → K+K− decays using 5.94 fb−1 of data collected by the displaced track trigger.The final results, which are the most precise up to date, are ACP (D0 → π+π−) =[+0.22± 0.24 (stat.)± 0.11 (syst.)]% and ACP (D0 → K+K−) = [−0.24± 0.22 (stat.)±B PHYSICS AT THE TEVATRON 850.10 (syst.)]% [21]. They are consistent with CP conservation and also with the SMpredictions. As expressed by eq. (3) of ref. [21] the ACP (D0 → h+h−) measurementdescribes a straight line in the plane (AindCP , AdirCP ) with angular coefficient given by 〈t〉/τ ,t being the measured proper decay time of the D0 candidates and τ the lifetime of theD0 meson. Because of a threshold on the impact parameter of tracks, imposed at triggerlevel, the CDF sample of D0 → π+π− (D0 → K+K−) decays is enriched in higher-valued proper decay time candidates with a mean value of 2.40(2.65)±0.03 (stat.+syst.)times the D0 lifetime, as measured from a fit to the proper time distribution. Due totheir unbiased acceptance in charm decay time, B factories samples have instead 〈t〉 ≈ τ .Hence, the combination of the three measurements allow to constrain independently bothAdirCP and AindCP [21].REFERENCES[1] CDF Collaboration, Note 9892.[2] Kong D. (for the CDF Collaboration), Talk at BEAUTY 2011, Amsterdam.[3] Abazov V. et al. (DØ Collaboration), Phys. Lett. B, 693 (2010) 539.[4] Aaltonen T. et al. (CDF Collaboration), Phys. Rev. Lett., 106 (2011) 161801.[5] Ali A. et al., Phys. Rev. D, 61 (2000) 074024.[6] Nakamura K. et al., J. Phys. G, 37 (2010) 075021.[7] Abulencia A. et al. (CDF Collaboration), Phys. Rev. Lett., 97 (2006) 242003.[8] Lenz A. and Nierste U., JHEP, 0706 (2007) 072.[9] CDF Collaboration, Note 10206.[10] DØ Collaboration, Note 6098.[11] Aaltonen T. et al. (CDF Collaboration), Phys. Rev. Lett., 100 (2008) 161802;Abazov V. M. et al. (DØ Collaboration), Phys. Rev. Lett., 101 (2008) 241801.[12] Aaij R. et al. (LHCb Collaboration), Phys. Lett. B, 698 (2011) 115; Li J. et al. (BelleCollaboration), Phys. Rev. Lett., 106 (2011) 121802.[13] CDF Collaboration, arXiv:1106.3682 [hep-ex] preprint (2011).[14] Abazov V. M. et al. (DØ Collaboration), Phys. Rev. D, 82 (2010) 032001.[15] Gronau M. and Wyler D., Phys. Lett. B, 265 (1991) 172.[16] Atwood D., Dunietz I. and Soni A., Phys. Rev. Lett., 78 (1997) 3257.[17] Giri A., Grossman Y., Soffer A. and Zupan J., Phys. Rev. Lett., 68 (2003) 054018.[18] CDF Collaboration, Note 10309.[19] Horii Y. et al. (Belle Collaboration), Phys. Rev. Lett., 106 (2011) 231803; del AmoSanchez P. et al. (BaBar Collaboration), Phys. Rev. D, 82 (2010) 072006.[20] Aaltonen T. et al. (CDF Collaboration), Phys. Rev. D, 81 (2010) 031105.[21] CDF Collaboration, Note 10296.

B physics at the Tevatron

The CDF and DO experiments at the Tevatron $par{p}$ collider established that extensive and detailed exploration of the $b$--quark dynamics is possible in hadron collisions, with results competitive and supplementary to those from $e^+e^-$ colliders. This provides a rich, and highly rewarding program that is currently reaching full maturity. I report a few recent world-leading results on rare decays, CP-violation in $B^0_s$ mixing, $b	o s$ penguin decays, and charm physics

B Physics at the TeVatron

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