The CDF and D0 experiments at the Tevatron p{bar p} collider have pioneered and established the role of flavor physics in hadron collisions. A broad program is now at its full maturity. We report on three new results sensitive to physics beyond the standard model, obtained using the whole CDF dataset: a measurement of the difference of CP asymmetries in K{sup +}K{sup -} and {pi}{sup +}{pi}{sup -} decays of D{sup 0} mesons, new bounds on the B{sub s}{sup 0} mixing phase and on the decay width difference of B{sub s}{sup 0} mass-eigenstates, and an update of the summer 2011 search for B{sub (s)}{sup 0} mesons decaying into pairs of muons. Finally, the D0 confirmation of the observation of a new hadron, the {chi}{sub b}(3P) state, is briefly mentioned

/Trieste U. /INFN, Trieste

Dorigo, Mirco

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RECENT HEAVY FLAVOR RESULTS FROM THE TEVATRONM. DORIGO on behalf of the CDF and D0 Collaborations.University of Trieste and INFN TriesteThe CDF and D0 experiments at the Tevatron pp̄ collider have pioneered and established therole of flavor physics in hadron collisions. A broad program is now at its full maturity. Wereport on three new results sensitive to physics beyond the standard model, obtained usingthe whole CDF dataset: a measurement of the difference of CP asymmetries in K+K− andπ+π− decays of D0 mesons, new bounds on the B0s mixing phase and on the decay widthdifference of B0s mass-eigenstates, and an update of the summer 2011 search for B0(s) mesonsdecaying into pairs of muons. Finally, the D0 confirmation of the observation of a new hadron,the χb(3P ) state, is briefly mentioned.1 Measurement of CP violation in charm in the final CDF datasetViolation of the CP symmetry in tree-dominated decays D0 → π+π− and D0 → K+K− is asensitive probe of physics beyond the standard model (SM). Both the D0–D̄0 mixing amplitudeand the SM-suppressed penguin amplitude can be greatly enhanced by new dynamics, which canalso increase the size of the CP violation over that expected from to the Cabibbo-Kobayashi-Maskawa (CKM) hierarchy. Last year, using 5.9 fb−1 of data, CDF produced the world’s mostprecise measurements of the CP asymmetriesACP(KK) = (−0.24±0.22±0.09)% andACP(ππ) =(0.22±0.24±0.11)%.1 In spite of the hadronic uncertainties, there is broad consensus that directCP asymmetries of D0 → K+K− and of D0 → π+π− should be of opposite sign. Therefore,a measurement of the difference between asymmetries of those decays is maximally sensitive todetect CP violation. Indeed, the LHCb collaboration reported recently the first evidence of CPviolation in charm measuring ∆ACP = ACP(KK) − ACP(ππ) = (−0.82 ± 0.21 ± 0.11)%.2 Anindependent measurement is crucial to establish the effect, and the 10 fb−1 sample of hadronicD decays collected by CDF is the only one currently available to attain sufficient precision.The analysis follows closely the measurement of individual asymmetries.3 The flavor of theD0 meson is tagged from the charge of the soft pion in the strong D?+ → D0π+ decay. SinceD?+ and D?− mesons are produced in equal number in strong pp̄ interactions, any asymmetrybetween the number of D0 and D̄0 decays is due to either CP violation or instrumental effects.The latter can be induced only by the difference in reconstruction efficiency between positiveand negative soft pions. Provided that the relevant kinematic distributions are equalized inthe two decay channels, the instrumental asymmetry cancels to an excellent level of accuracyin the difference between the observed asymmetries between signal yields. Such cancellationallows one to increase the sensitivity on ∆ACP by loosening some selection criteria with respectto the measurement of individual asymmetries and double the signal yields. The trigger isfired by two charged particles with transverse momenta greater than 2 GeV/c. The excellentCDF momentum resolution yields precise mass resolution (∼8 MeV/c2 for D mesons) whichprovides good signal-to-background. The typical resolution (50 µm) on the impact parameter(IP) of the tracks is effective to trigger on good kaon or pion candidates, that are required tohave IP>100 µm. The offline selection adds some basic additional requirements on track andvertex quality. The numbers of D0 and D̄0 decays are determined with a simultaneous fit tothe D0π-mass distribution of positive and negative D? decays (see Fig. 1, left). About 1.21million D0 → K+K− decays and 550 thousand D0 → π+π− decays are reconstructed, yieldingthe following observed asymmetries between signal yields, Araw(KK) = (−2.33 ± 0.14)% andFERMILAB-CONF-12-244-EOperated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy. 2.005 2.01 2.015 2.025101520310×+sπ) -π+π → (0 D→ +D*2.005 2.01 2.015 2.0205000100001500020000-sπ) -π+π → (0D → -D*)-1Data (9.7 fbFitD decaysMultibodyRandom pionsCDF Run II Preliminary2.005 2.01 2.0150102030405010×+sπ) -K+ K→ (0 D→ +D*2.005 2.01 2.015 2.0201000020000300004000050000 -sπ) -K+ K→ (0D → -D*]2-mass [GeV/csπ0Invariant D2Candidates per 0.1 MeV/c [rad]φψJ/sφ-3 -2 -1 0 1 2 3]-1 [pssΓ∆-0.6-0.4-0.200.20.40.6-1CDF Run II Preliminary L = 9.6 fb A. Lenz and U. Nierste, arXiv:1102.4274v1 (2011)1-1 0.021) ps±|= (0.087 12Γ 2|268% CL  95% CL 1SM expectationSymmetry line2Mixing Induced CP ViolationFigure 1: Left: D0π-mass distributions of positive and negative D? decays with fit projections overlaid.Right: 68% and 95% confidence regions in the plane (φs,∆Γs) from profile-likelihood of CDF data.Araw(ππ) = (−1.71 ± 0.15)%. Residual systematic uncertainties total 0.10% and are drivenby differences between distributions associated with charm and anticharm decays. The finalresult is ∆ACP = (−0.62 ± 0.21 ± 0.10)%, which is 2.7σ different from zero. This providesstrong indication of CP violation in CDF charm data, supporting the LHCb earlier evidencewith same resolution. The combination of CDF, LHCb and B-factories measurements deviatesby approximately 3.8σ from the no CP violation point.2 Measurement of the B0s → J/ψϕ time-evolution in the final CDF datasetThe B0s–B̄0s mixing is a promising process where to search for new physics (NP), given the D03.9σ anomaly in dimuon charge asymmetry.4 If the anomaly is due to new dynamics in theB0s sector, the phase difference between the B0s–B̄0s mixing amplitude and the amplitude of B0sand B̄0s decays into common final states, φs, would be significantly altered with respect to itsnearly vanishing value expected in the SM. A non-CKM enhancement of φs can also decreasethe decay width difference between the heavy and light mass-eigenstate of the B0s meson, ∆Γs.The analysis of the time evolution of B0s → J/ψϕ decays is the most effective experimental probeof such a CP-violating phase. Since the decay is dominated by a single real amplitude, the phasedifference equals the mixing phase to a good approximation. Early Tevatron measurements haveshown a mild discrepancy of about 2σ with the SM expectation.5 Latest updates by CDF andD0 are in better agreement with the SM, as well as first measurements provided by LHCb.6,7,8Here we report the new CDF update using the final dataset of 10 fb−1 which comprisesabout 11000 B0s → J/ψϕ decays collected by a low-momenta dimuon trigger.9 The decays arefully reconstructed through four tracks that fit to a common displaced vertex, two matched tomuon pairs consistent with a J/ψ decay, and two consistent with a φ→ K+K− decay. A joint fitthat exploits the candidate-specific information given by the B mass, decay time and productionflavor, along with the decay angles of kaons and muons, is used to determine both φs and ∆Γs.The analysis closely follows the previous measurement obtained on a subset of the data.6 Theonly major difference is the use of an updated calibration of the tagging algorithm that usesinformation from the decay of the “opposite side” bottom hadron in the event to determinethe flavor of the B0s at its production, with tagging power (1.39 ± 0.01)%. The informationfrom the tagger that exploits charge-flavor correlations of the neighboring kaon to the B0s isinstead restricted to only half of the sample, in which has tagging power (3.2 ± 1.4)%. Thisdegrades the statistical resolution on φs by no more than 15%. A decay-resolution of ∼90fs allows resolving the fast B0s oscillations to increase sensitivity on the mixing phase. The68% and 95% confidence regions in the plane (φs,∆Γs) obtained from the profile-likelihood ofthe CDF data are reported in Fig. 1 (right). The confidence interval for the mixing phase isφs ∈ [−0.60, 0.12] rad at 68% C.L., in agreement with the CKM value and recent D0 and LHCbdeterminations.7,10 This is the final CDF measurement on the B0s mixing phase, and providesa factor 35% improvement in resolution with respect to the latest determination. CDF alsoreports ∆Γs = (0.068 ± 0.026 ± 0.007) ps−1 under the hypothesis of a SM value for φs, alongwith the measurement of the B0s lifetime, τs = (1.528 ± 0.019 ± 0.009) ps, in agreement withother experiments’ results.7,103 Final search for dimuon decays of B mesons at CDFThe B0(s) → µ+µ− decays involve flavor changing neutral currents and the observation of anabnormal decay rate can provide excellent evidence of NP since in the SM they can occur onlythrough high-order loop diagrams. Enhancements to the SM expectation of their branchingratios (BR) can indeed occur in a variety of different NP models. Last summer CDF reportedan intriguing ∼2.5σ fluctuation over background in 7 fb−1 of data. Even if compatible with theSM and other experiments’ results, it allowed the first two sided bound on the B0s → µ+µ−rate.11Here we report the CDF update of the analysis with the final 10 fb−1 dataset.12 The analysismethods are not changed from the previous iteration to ensure the unbiased processing of newdata. The events are collected using a set of dimuon triggers and are divided in two categories:“CC” events have both muon candidates in the central region of the detector, while “CF” eventshave one central muon and another muon in the forward region. The signal candidates are fullyreconstructed with a secondary vertex due to the long B0s lifetime (∼450 µm). They also featurea primary-to-secondary vertex vector aligned with the B0s candidate momentum and a veryisolated B0s candidate. There are two sources of background: combinatorial background andpeaking background. The former tends to be partially reconstructed and shorter-lived thansignal. It is estimated by extrapolating the number of events in the sideband regions of the Bmass distribution to the signal window using a linear fit. The peaking background are due todecays of B0s and B0 mesons to pions and kaons that are misreconstructed as muons, and it isten times greater in the B0 search with respect to the B0s analysis. It is carefully taken intoaccount with simulation (mass shape) and with D0 → Kπ decays from data (misidentificationprobability). A neural network (NN) classifier is optimized to reject the background using 14event variables. The background estimates are checked to be consistent in many control samples.Finally, when the background is well understood, the number of observed events is compared tothe number expected. The data are found to be consistent with the background expectationsfor the B0 → µ+µ− decay and yield an observed limit of BR < 4.6 × 10−9 at 95% C.L (withexpected limit 4.2×10−9). In the case of B0s → µ+µ− the summer 2011 excess is not reinforced,even though it is still present as shown in the most sensitive (top-right) bin of the NN in Fig. 2.The resulting bounds at 95% C.L. are 0.8× 10−9 < BR < 3.4× 10−8, which is still compatibleboth with the SM expectation and the latest limits from LHC experiments.13 An upper limit at95% C.L. of BR < 3.1× 10−8 (expected 1.3× 10−8) is also derived.4 A new state decaying into Υ(1S) + γUsing data corresponding to an integrated luminosity of 1.3 fb−1, the D0 collaboration observesa narrow mass state decaying into Υ(1S) + γ, where the Υ(1S) meson is detected by its decay0510CC 0.2× < 0.97Nν0.70 <  < 0.987Nν0.97 <  < 0.995Nν0.987 <  > 0.995Nν-µ+µ→0sB )2 (MeV/cµµm05105322 5370 5418 5322 5370 5418 5322 5370 5418 5322 5370 5418CF 0.2× < 0.97Nν0.70 <  < 0.987Nν0.97 <  < 0.995Nν0.987 <  > 0.995NνBackground4.1)×+Signal (SM 2Candidates per 24 MeV/cCDF Run II Preliminary ] 2 [GeV/c(1S)Υ + mµµ - MγµµM9.5 10 10.5 11 11.52Events /  50 MeV/c051015202530354045DataFull fitBkg only(1P)bχ(2P)bχNew state-1DØ, 1.3 fbFigure 2: Left: comparison of the CDF B0s → µ+µ− data (points ) and expected background (solid grey) for CCand CF muons. Right: mass distribution of Mµµγ −Mµµ +MΥ(1S) of D0 data with fit overlaid.into a muons pair, and the photon through its conversion into an e+e− pair.14 The fit to the massspectrum in Fig. 2 (right) shows three structures above a smooth, threshold-like background.The one at the highest mass has a statistical significance of 5.6σ. It is interpreted as the stateχb(3P ) and is centered at 10.551 ± 0.014 ± 0.017 GeV/c2, consistent with the recent ATLASobservation.155 ConclusionsWe reported the final CDF results on three flagship measurements in the indirect search for NPat Tevatron, and the confirmation of a new hadron (χb(3P )) by the D0 collaboration. The CPasymmetries of D0 meson decays reported by CDF confirm the first evidence of CP violationin charm reported by LHCb; in the B0s sector, tensions with SM predictions are now softenedby latest updates of φs and ∆Γs bounds, making the D0 Asl anomaly even harder to depuzzle.The final CDF update on the B0s → µ+µ− rate is concluding a decade-long program of Tevatronsearches that improved the experimental bounds on the rate down to the 10−8 range, nearingnow the sensitivity to observe a SM signal. Analyses of the unique (pp̄ charge-symmetric), rich(e.g., millions of charm decays), and well-understood (10-years expertise) data sample acquiredby CDF and D0 are still in progress and may reserve interesting results in the near future.References1. T. Aaltonen et al. (CDF Collaboration), Phys. Rev. D 85, 012009 (2012).2. R. Aaij et al. (LHCb Collaboration), Phys. Rev. Lett. 108, 111602 (2012).3. T. Aaltonen et al. (CDF Collaboration), CDF Note 10784 (2012).4. V. M. Abazov et al. (D0 Collaboration), Phys. Rev. D 84, 052007 (2011).5. CDF and D0 Collaborations, CDF Note 9787, D0 Note 5928 (2009).6. T. Aaltonen et al. (CDF Collaboration), Phys. Rev. D 85, 072002 (2012).7. V. M. Abazov et al. (D0 Collaboration), Phys. Rev. D 85, 032006 (2012).8. R. Aaij et al. (LHCb Collaboration), Phys. Rev. Lett. 108, 101803 (2012)9. T. Aaltonen et al. (CDF Collaboration), CDF Note 10778 (2012).10. R. Aaij et al. (LHCb Collaboration), LHCb-CONF-2012-002.11. T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett. 107, 191801 (2011).12. http://www-cdf.fnal.gov/physics/new/bottom/120209.blessed-bmumu10fb.13. CMS PAS BPH-11-020; ATLAS-CONF-2012-010; LHCb-PAPER-2012-007.14. V. M. Abazov et al. (D0 Collaboration), arXiv:1203.6034 [hep-ex].15. Georges Aad et al. (ATLAS Collaboration), Phys. Rev. Lett. 108, 152001 (2012).

Recent heavy flavor results from the Tevatron

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Recent heavy flavor results from the Tevatron

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