A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315??nb-1 collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C.L. the q* mass interval 0.30(mq*(1.26??TeV, extending the reach of previous experiments.
COBISS.SI-ID: 24118055
By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the LHC. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.
COBISS.SI-ID: 24297767
The most accurate measurement of the purely leptonic branching fraction of Bs mesons. The measurement constraints the parameters describing the charged Higgs boson predicted in some supersymmetric extensions of the SM.
COBISS.SI-ID: 24336167
The Dalitz analysis of the D0 decay products enables the most accurate determination of the unitary triangle angle phi_3 which parametrizes the violation of the CP symmetry. Within the accuracy the results are in agreement with measurements of other parameters of the unitary triangle and predictions of the SM.
COBISS.SI-ID: 24330535
Measurement of the Bs › Ds(*)Ds(*) decay width enables the determination of the mixing and CP violation parameters for the Bs mesons, Delta Gamma / cos(phi). It can be used to constrain possible values of the CP violating parameter cos(phi).
COBISS.SI-ID: 24334375