D Ø Calorimeter Algorithms & Objects

1. DØ Calorimeter Algorithms & Objects Krisztian Peters University of Manchester Dec. 20th, 2006 Annual Group Meeting, Manchester D0 Calorimeter Algorithm & Objects

2. Calgo • My main time consuming tasks at the moment are within the DØ Calorimeter Algorithm & Objects Group, (where I am group convener) D0 Calorimeter Algorithm & Objects

3. RunIIb calorimeter calibration • Since Oct. 100%: coordinate, supervise and actively participate in the calorimeter calibration after the major shutdown • Determine energy scale (i.e. multiplicative correction factor), if possible per cell • Factorize roughly into two parts (LAr): • First: Calibration of the EM CAL • Second: Calibration of the HCAL • 1st: f-intercalibration to reduce the number of degrees of freedom • Use special triggered RunIIb data • 2nd: h-intercalibration to get access to the remaining degrees of freedom, as well as the absolute scale for the EM CAL • for the EM CAL and QCD dijet events for the HCAL • Intercryostat detector: scintillation counter arrays between the cryostat walls.We have to deal withaging PMTs which depend on the instantaneous luminosity:new and involved development D0 Calorimeter Algorithm & Objects

4. Isolated pion studies • Quantify, understand and possibly further improve the response and resolution of the CAL to hadrons • The definite understanding of the single pion response has to come from studies in situ Need to obtain isolated pion sample with the final detector setup • Have to handle large backgrounds: neutral energy overlap, tracks not due to pions. Requires detailed understanding of various detector parts and MC models • Provide feedbackto the development of the full GEANT based DØ detector simulation • Direct input and essential for the development of Eflow algorithms(to improve jet energy resolution) • Tau energy resolution. Basic idea is the same as for Eflow (next slide) • Analysis is converging, I am working on the neutral background subtraction and the final understanding of the results D0 Calorimeter Algorithm & Objects

5. Improving tau energy scale using tracks • Investigate the impact of different methods on the tau energy resolution for hadronic tau decays • Aim is to find a method which yields a better energy resolution compared to the one of the calorimeter alone • Hadronic taus decay into several charged and neutral pions (and neutrinos), based on these decays they are divided into 3 types • Basic idea:at lower energies tracking is more accurate than the CAL Measure charged pions with the tracker and neutral ones with the calorimeter (need to avoid double counting of the CAL energy) • Various modifications of this basic idea exist, they lead to different results depending on the tau type, energy and rapidity of the decay products. Determined the best method in these various kinematical ranges D0 Calorimeter Algorithm & Objects

6. Higgs analysis, conferences, papers • Started to work on the channel zh→nnbbtogether with Remi, and in close cooperation with Philip who will analyze wh→tnbb • Complete analysis chain is (almost) set up. Our aim is to converge with wh→tnbb for Moriond and with zh→nnbb for the summer conferences • Further work on and DIS’06 presentation of our phenomenological studies: Non-linear gluon evolution and heavy quark production at the LHC. This work mainly addresses the question:What is the region of applicability of PDFs and of linear QCD evolution? • CALOR’06 presentation on: Precision calibration of the DØ HCALin Run II • Finished paper: The Pomeranchuk singularity and vector boson reggeization in electroweak theory. High energy behaviour of vector boson scattering in the electroweak sectorof the standard model in analogy with the BFKL analysis in QCD D0 Calorimeter Algorithm & Objects