Krzysztof Piotrzkowski

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A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9 pb⁻¹ collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately(More)
The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract Observation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions(More)
Exclusive production of 0 and J== mesons in e + p collisions has been studied with the ZEUS detector in the kinematic range 0:25 < Q 2 < 50 GeV 2 , 20 < W < 167 GeV for the 0 data and 2 < Q 2 < 40 GeV 2 , 50 < W < 150 GeV for the J== data. Cross sections for exclusive 0 and J== production have been measured as a function of Q 2 , W and t. The spin-density(More)
Search for supersymmetry in hadronic final states with missing transverse energy using the variables α T and b-quark multiplicity in pp collisions at √ s = 8 TeV Abstract An inclusive search for supersymmetric processes that produce final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of 8 TeV. The(More)
A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a bb quark pair. The searches use the 8 TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of(More)
Computing the trajectories of particles in generic beamlines is an important ingredient of experimental particle physics, in particular regarding near-beam detectors. A new tool, Hector, has been built for such calculations, using the transfer matrix approach and energy corrections. The limiting aperture effects are also taken into account. As an(More)
Using the ZEUS detector at HERA, we have studied the reaction e + p ! e + X for Q 2 > 5000 GeV 2 with a 20:1 pb ?1 data sample collected during the years 1994 to 1996. For Q 2 below 15000GeV 2 , the data are in good agreement with Standard Model expectations. For Q 2 > 35000 GeV 2 , two events are observed while 0:145 0:013 events are expected. A(More)
Results are presented from a search for particle dark matter (DM), extra dimensions, and unparticles using events containing a jet and an imbalance in transverse momentum. The data were collected by the CMS detector in proton–proton collisions at the LHC and correspond to an integrated luminosity of 19.7 fb −1 at a centre-of-mass energy of 8 TeV. The number(More)
A search for a standard-model-like Higgs bo-son in the H → WW and H → ZZ decay channels is reported , for Higgs boson masses in the range 145 < m H < 1000 GeV. The search is based upon proton–proton collision data samples corresponding to an integrated luminos-ity of up to 5.1 fb −1 at √ s = 7 TeV and up to 5.3 fb −1 at √ s = 8 TeV, recorded by the CMS(More)