1 / 21

B physics prospects with Atlas and CMS

B physics prospects with Atlas and CMS. M.Smizanska, LancasterUniversity,UK maria.smizanska@cern.ch. Experimental conditions. Trigger strategies.

toviel
Download Presentation

B physics prospects with Atlas and CMS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. B physics prospects with Atlas and CMS M.Smizanska, LancasterUniversity,UK maria.smizanska@cern.ch

  2. Experimental conditions B physics prospects in ATLAS and CMS

  3. Trigger strategies B physics prospects in ATLAS and CMS

  4. 1. Both ATLAS and CMS detectors layouts have been changed over last 2 years. Some of the changes have been accepted as permanent ones, while some of them represent only staging over the initial LHC period. 2. Intensive studies in both ATLAS and CMS are in progress to understand the performance under the new conditions and several scenarios. Different topics are in different stages of understanding. In order to give a consistent picture of all the physics processes ATLAS and CMS decided to present all the studies within the original detector layouts and scenario. 3. Unless otherwise said the ATLAS and CMS results are shown for statistics measured in 3 years at luminosity 1033cm-2 s-1 B physics prospects in ATLAS and CMS

  5. Precise measurements in B decays Can LHC investigate different CP violation mechanisms in Bd  J/yKs0? In time-dependent analyses the decay probabilities of neutral B mesons are conveniently parametrized in terms of two phenomenological amplitudes Amix , Adir : Experimental inputs are: proper decay time, invariant mass, tag probability, wrong tag fraction and background composition. Neglecting other then mixing CP violation the measured time-dependent asymmetry: Amix sinDmt = D sin2b sinDmt D - overall dilution factor due to tagging and background CKM triangle will be over constrained and discrepancies would indicate New Physics.Amix the mixing induced amplitude may exhibit a weak phase shift due to New Physics contri-butions to DB=2 process Amix = - sin(2b +fNP) B physics prospects in ATLAS and CMS

  6. Precise measurements in B decays,continue Bd  J/yKs0 , direct CP violation 1. ATLAS+CMS+LHCb simultaneous fit of both Amix and Adir leads to statistical error dAdir~0.01. Observation of Adir of level 0.1 would be indication of New physics. 2. Direct CP violation: increase precision by using combined variables: Adir + ACP and Adir - ACP , where Adir determined from Bd  J/yKs0and ACP fromB+ J/y K+ The present Babar results indicate (0.04 +- 0.06) identical with 0. The expected statistics of B+ J/y K+ in ATLAS alone (3years) is 5 x 106. B physics prospects in ATLAS and CMS

  7. Precise measurements in B decays,continuation Search for physics beyond SM in B+K+K-p- With significance S/ =3 an upper limit on BR(B+K+K-p-)=5.3 x 10-7 3years@1033cm-2 s-1 B physics prospects in ATLAS and CMS

  8. sensitivity in 1. Divergencies appeare as sin or cos->1 2. Linear |P/T| approximation is not justified for value 0.36 suggested by current evaluations. 3. The current theoretical uncertainty |P/T|~30% dominates other systematical and statistical errors of full LHC potential. Exact: |P/T|2 Approx: |P/T| B physics prospects in ATLAS and CMS

  9. Physics of Bs mesons ATLAS and CMS prepare a program for precise measurements of Bs-anti-Bs system parameters : DGs, Dms and probing Bs mixing phase fs= -2l2hallowing to indicate new physics phenomena . Precision measurements of Dms: already after 1 year fully explore SM allowed range Dms (14.3 - 26) ps-1 4 dedicated presentations of ATLAS and CMS are on Bs topics: 1. A.Nairz Search for Bs oscillations with 2. G.Segneri Bs oscillations with CMS 3. R.Ranieri Study of Bs->J/yf at CMS 4. F.Ohlson-Malek Potential of Bs->J/yh in ATLAS B physics prospects in ATLAS and CMS

  10. Physics of Bs mesons, continuation Determination of DGs and fs= -2l2h Angular analyses of cascade decay Bs->J/yf->mmKK determine DGs, Gs and fs simultaneously with parameters of helicity amplitudes A||(t=0), AT(t=0), A0(t=0), d1, d2; using the maximum likelihood fit. Parameter Dms to be measured by flavour specific decays. Both sensitive, but statistics of reconstructed events dominated by f q1 q2 Bs B physics prospects in ATLAS and CMS

  11. Physics of Bs mesons, continuation xs - fs region Allowed by Standard Model by New physics Left-right symmetric model (NP-LR) Regions of experimental sensitivity: CMS(3Y): for 1st level triggers 1m, 2m, e-e, e+m ATLAS (3y): for 1st level trigger 1m only. Extension by 2m trigger under investiga- tion, not included. LHCb(5Y): full 1st Level trigger Experimental potential of 3 experiments not yet fully exploited: more studies on additional triggers, tagging, J/y(ee) under way. CP - violation weak phase in Bs->J/y f B physics prospects in ATLAS and CMS

  12. Physics of Bs mesons, conclusions 1. Already after 1 year fully explore Dms range allowed today by SM. 2. Precision on Dms with full LHC data will be such that extraction of |Vtd|/|Vts| will likely be limited by theoretical uncertainty of QCD calculation. 3. DGs can be measured with relative precision better then 8-12% for DGs/Gs=15% by each experiment. 4. There is sensitivity close to the range of fs allowed in SM and clear potential for probing models containing new physics. B physics prospects in ATLAS and CMS

  13. Potential for Rare decays FCNC decay bs, bd at SM only at loop level: exclusive Br<O(10-5). Sensitive to new physics. Within SM sensitive to |Vtd|, |Vts| - complementary to determination from Dms. Before LHC BK*mm will be measured but mass and angular distributions only at LHC. Bmm can be seen before LHC only if drastically enhanced LHC era: radically increase statistics from e+e- factories and Tevatron 1 year at nominal LHC luminosity 1034cm-2 s-1 3 years at luminosity 1033cm-2 s-1 Different conclusions about BG: 1.CMS - already exploit isolation cuts in calorimetry, 2. Different assumptions about tails in VTX resolution. B physics prospects in ATLAS and CMS

  14. Exclusive Rare decays of B mesons LHC statistics will allow angular analyses that can carry evidence for new physics. E.g. forward-backward asymmetry: Three points: mean values of AFB in three q2/MB2 experimental regions with error bars Lowest mass region: sufficient accuracy to separate SM and MSSM if Wilson coefficient C7g <0 SM MSSM C7g >0 MSSM C7g <0 B physics prospects in ATLAS and CMS

  15. Potential for Rare decays, conclusion • 1. Improve + radically increase statistics from e+e- factories and Tevatron on b->s b->d exlusive rare decays • 2. Simulations showed that ATLAS and CMS are capable to measure B->mm also at nominal LHC luminosity 1034cm-2 s-1 • 3. Will measure branching ration of Bs ->mm which is in SM of order Br<(10-9) • 4. Perform high sensitivity search on Bd ->mm • B->K*mm FB asymmetry precision will allow to distinguish between SM and certain classes of MSSM. B physics prospects in ATLAS and CMS

  16. B production at LHC p-p collisions Bjorken x region: one of B’s in detector volume: LHCb most sensitive to knowledge of structure functions at very low x Common part of phase space: opportunity for normalization checks in Beauty Cross-section measurements CDF ATLAS/CMS LHCb B physics prospects in ATLAS and CMS

  17. B production at LHC, continue CDF and D0 measurement of beauty cross section in barrel region: QCD - NLO describe the shape of differential cross section however underestimates absolute value of cross section by factor ~2.4. Better agreement at higher pT covered by new D0 measurement based on b-jets . B physics prospects in ATLAS and CMS

  18. B production at LHC, continue CDF measurement of b-b correlation using m - b-jet data and comparison to models. LHC statistics will allow using of exclusive channel instead of b-jet PYTHIA PYTHIA all QCD 3 points where the model dependent acceptance correction was used to correct for isolation cut between m and b-jet gb->gb g->bb Semihard gg->bb B physics prospects in ATLAS and CMS

  19. B production at LHC, continue ATLAS - proposal for measurement of b-b production correlations using exlusive B-decay and semi leptonic decay to muon Bm Bs  J/yf Bm Bd  J/yKs0 Df=f J/y - fm No degradation of efficiency as b-b close in space. In Bs case – interesting specific background Kmoriginating from s-quark associated with Bs production. Need Be Bs  J/yf B physics prospects in ATLAS and CMS

  20. Measurement of Lb production polarization In p-p collisions Lb baryon will be polarized perpendicularly to production plane. The polarization vanish as h 0 because of p-p symmetry. At LHCb polarization higher then ATLAS/CMS. Angular distribution LbJ/y(mm)L(pp) depends on 5 angles (fig) + 6 parameters of 4 helicity amplitudes and polarization Pb . Helicity amplitudes and Pb – simultaneously determined. 75000 LbJ/y(mm)L(pp) in3years will allow precision dPb 0.016. q1 q1 p q f2 q2 Lb p n p p B physics prospects in ATLAS and CMS

  21. B-physics prospects with ATLAS and CMS - conclusions General purpose central LHC detectors ATLAS and CMS are well equipped for multi thematic B-physics program - including B-decays and B-production. 1. In CP violation the main emphasis will be on underlying mechanisms and evidence of New physics. ATLAS and CMS are especially precise in measurement of b. LHC ‘gold-platted’ mode is also Bs->J/y f 2. Bs mixing studies make clear that there is sensitivity to Dms far beyond SM expectations. The width difference DGs can be measured best in Bs->J/y f. 3. Rare decays B->mm have the most favorable experimental signature allowing to measure also at nominal LHC luminosity 1034cm-2 s-1. Will measure branching ration of Bs ->mm which is in SM of order Br<(10-9) Precision measurements will be done for B->K*mm. 4. Beauty production and correlations at central LHC collisions will be measured for QCD tests. The program includes baryon production polarizations. 5. ATLAS and CMS beauty trigger strategies will be adapted according to luminosity conditions at initial LHC period. B physics prospects in ATLAS and CMS

More Related