The MPD detector at the NICA heavy-ion collider at JINR Afanasiev, S.V.; Alfeev, V.S.; Aslanyan, P.Zh ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
628, Številka:
1
Journal Article
Recenzirano
The MultiPurpose Detector (MPD) is designed to study heavy-ion collisions at the Nuclotron-based heavy Ion Collider fAcility (NICA) at JINR, Dubna. Its main components located inside a ...superconducting solenoid are a tracking system composed of a silicon microstrip vertex detector followed by a large volume time-projection chamber, a time-of-flight system for particle identification and a barrel electromagnetic calorimeter. A zero degree hadron calorimeter is designed specifically to measure the energy of spectators. In this paper, all parts of the apparatus are described and their tracking and particle identification (PID) parameters are discussed in some detail.
New developments of the CompHEP package and its applications to the top quark and the Higgs boson physics at the LHC collider are reviewed. These developments were motivated mainly by the needs of ...experimental searches of DO (Tevatron) and CMS (LHC) collaborations where identification of the top quark and the Higgs boson in the framework of the Standard Model (SM) or possible extensions of the SM played an important role. New useful features of the CompHEP Graphics User Interface (GUI) are described.
We present measurements of direct photon pair production cross sections using 8.5 fb−1 of data collected with the D0 detector at the Fermilab Tevatron pp¯ collider. The results are presented as ...differential distributions of the photon pair invariant mass dσ/dMγγ, pair transverse momentum dσ/dpTγγ, azimuthal angle between the photons dσ/dΔϕγγ, and polar scattering angle in the Collins–Soper frame dσ/d|cosθ⁎|. Measurements are performed for isolated photons with transverse momenta pTγ>18(17) GeV for the leading (next-to-leading) photon in pT, pseudorapidities |ηγ|<0.9, and a separation in η–ϕ space ΔRγγ>0.4. We present comparisons with the predictions from Monte Carlo event generators diphox and resbos implementing QCD calculations at next-to-leading order, 2γnnlo at next-to-next-to-leading order, and sherpa using matrix elements with higher-order real emissions matched to parton shower.
Muon reconstruction and identification with the Run II D0 detector Abbott, B.; Adams, M.; Adams, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2014, Letnik:
737
Journal Article
Recenzirano
Odprti dostop
We present an overview of the muon reconstruction and identification methods employed by the D0 collaboration to analyze the Run II (2001–2011) pp¯ data of the Fermilab Tevatron collider at ...s=1.96TeV. We discuss the performance of these methods, how it is measured using D0 data, and how it is properly modeled by the D0 simulation program. In its pseudorapidity acceptance, |η|<2, the muon system identifies high-pT muons (pT≳10GeV) with efficiencies ranging from 72% to 89%. Muons tracks are reconstructed in the D0 central tracking system with efficiencies ranging from 85% to 92% and with a typical relative momentum resolution of 10% for pT=40GeV. Isolation criteria reject multijet background with efficiencies of 87–99%.
We present a search for the standard model Higgs boson in final states with an electron or muon and a hadronically decaying tau lepton in association with zero, one, or two or more jets using data ...corresponding to an integrated luminosity of up to 7.3 fb−1 collected with the D0 detector at the Fermilab Tevatron collider. The analysis is sensitive to Higgs boson production via gluon–gluon fusion, associated vector boson production, and vector boson fusion, and to Higgs boson decays to ττ, WW, ZZ and bb¯ pairs. Observed (expected) limits are set on the ratio of 95% C.L. upper limits on the cross section times branching ratio, relative to those predicted by the Standard Model, of 22 (14) at a Higgs boson mass of 115 GeV and 6.8 (7.7) at 165 GeV.
Energy scales in a stabilized brane world Boos, Edward E.; Mikhailov, Yuri S.; Smolyakov, Mikhail N. ...
Nuclear physics. B,
06/2005, Letnik:
717, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Brane world gravity looks different for observers on positive and negative tension branes. First we consider the well-known RS1 model with two branes embedded into the
AdS
5
space–time and recall the ...results on the relations between the energy scales for an observer on the negative tension brane, which is supposed to be “our” brane. Then from the point of view of this observer we study energy scales and masses for the radion and graviton excitations in a stabilized brane world model. We argue that there may be several possibilities leading to scales of the order 1–10 TeV or even less for new physics effects on our brane. In particular, an interesting scenario can arise in the case of a “symmetric” brane world with a nontrivial warp factor in the bulk, which however takes equal values on both branes.
We present a measurement of the ratio of multijet cross sections in p p A= collisions at s = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set corresponding to an ...integrated luminosity of 0.7 fb - 1 collected with the D0 detector. The ratio of the inclusive three-jet to two-jet cross sections, R 3 / 2 , has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the pythia event generator do not agree with the data, while sherpa provides a reasonable description of the data. A perturbative QCD prediction in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects, gives a good description of the data.
We present measurements of the differential cross section d I / d p T gamma for the associated production of a c-quark jet and an isolated photon with rapidity | y gamma | 15 GeV . The ratio of ...differential cross sections for gamma + c to gamma + b production as a function of p T gamma is also presented. The results are based on data corresponding to an integrated luminosity of 8.7 fb - 1 recorded with the D0 detector at the Fermilab Tevatron p p A= Collider at s = 1.96 TeV . The obtained results are compared to next-to-leading order perturbative QCD calculations using various parton distribution functions, to predictions based on the k T -factorization approach, and to predictions from the sherpa and pythia Monte Carlo event generators.
We present searches for the anomalous gamma WW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from W gamma , WW, ...and WZ production with leptonic final states. The analyzed data correspond to up to 8.6 fb - 1 of integrated luminosity collected by the D0 detector in p p A= collisions at s = 1.96 TeV . We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters I kappa gamma , I>, and I g 1 Z for a cutoff energy scale I = 2 TeV . The combined 68% C.L. limits are - 0.057 < I kappa gamma < 0.154 , - 0.015 < 0.028 , and - 0.008 < I g 1 Z < 0.054 for the LEP parameterization, and - 0.007 < I kappa < 0.081 and - 0.017 < 0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to ...parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance IR in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of IR and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider in p p A= collisions at s = 1.96 TeV . The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50a400 GeV.
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