Since the Easter break the activity in the Physics Coordination area has steadily increased on fronts.
The approaching of Summer Conferences is reflected in an increased rate of approvals.
The Heavy Ion group has started its analysis campaign for QuarkMatter 2014. No fewer than 14 new analyses are en route to being presented there; six of these have already been approved. Among these analyses: an extension of the two- and four-particle correlations studies to six- and eight-particle correlations for both pPb and PbPb collisions (HIN-14-006); the measurement of the production cross section of Z bosons, as a function of pT and pseudorapidity, for pPb collisions (HIN-14-003) and the measurement of the jet nuclear modification factor RAA in pPb collisions, for both light and b quarks (HIN-14-001 and HIN-14-007).
Two important analyses, just approved and presented for the first time at DIS 2014, aim at giving a better tuning of PDF and of the underlying event in preparation of the 13 TeV run:
⁃ SMP-13-013 presents a measurement of the doubly differential Drell-Yan cross section as a function of the Z pT and rapidity in the Z peak region at 8 TeV. This measurement has the potential to constrain the gluon PDF in a kinematic region relevant for Higgs phenomenology;
⁃ GEN-14-001 uses our dN/dY analysis, together with CDF results at lower energies, to derive a substantially improved underlying event tuning.
The TOP group has also finalized and approved an impressive list of four analyses in the last few days. The measurements of the production cross sections for three processes, namely ttbar with a tau in the final state, accompanied by and electron or a muon (TOP-12-026), and the ttW and ttZ final states, show no discrepancies with respect to the Standard Model expectations. Both analyses are aiming at producing directly a publication. Flavour-changing neutral currents are also searched for in single top events. No signs of a deviation from the SM expectation are found and stringent limits, in many cases the best to date, are set on anomalous tcγ, tuγ, tcg, tug couplings (TOP-14-003 and TOP-14-007)
On the Higgs front we have two important news:
⁃ the requested additions to the Higgs width paper (HIG-14-002) have been approved during the WGM meeting of Apr. 30th. The inclusion of the 7 TeV data for the four-lepton final state, of the EW NLO correction and the combination of low- and high-mass region do not change substantially the final result that sports now an upper limit on Γ of 22 MeV (33 expected) @ 95% CL.
⁃ our paper on the evidence of fermionic decays of the Higgs (HIG-13-033) has just been accepted for publication by Nature.
In preparation for data taking in 2015, an important milestone has been achieved with a very first definition of the miniAOD format. This initial format has been discussed in a PPD meeting (https://indico.cern.ch/event/315313/contribution/1/material/slides/0.pdf) and implemented in a CMSSW_7_1_X pre-release. The format is still under active development in order to optimize its content. Nevertheless, its first incarnation provides a reduction factor with respect to the “standard” AOD format of one order of magnitude. The full potential of the miniAOD will be studied in more detail in the upcoming CSA14 exercise.
by Luca Malgeri
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