We present the observation of doubly-produced $J/\psi$ mesons with the D0 detector at Fermilab in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV. The production cross section for both singly and ...doubly-produced $J/\psi$ mesons is measured using a sample with an integrated luminosity of 8.1~fb$^{-1}$. For the first time, the double $J/\psi$ production cross section is separated into contributions due to single and double parton scatterings. Using these measurements, we determine the effective cross section \sigteff, a parameter characterizing an effective spatial area of the parton-parton interactions and related to the parton spatial density inside the nucleon.
Here, the inclusive cross section of top quark-antiquark pairs produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton+jets and dilepton decay channels. The data sample ...corresponds to 9.7 fb-1 of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of σ$t\bar{t}$=7.26±0.13(stat)$+0.57\atop{-0.50}$(syst) pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is mt=172.8±1.1(theo)$+3.3\atop{-3.1}$(exp) GeV.
Measurement of the W boson mass with the D0 detector Acharya, B. S.; Augsten, K.; Bagby, L. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
2014, Letnik:
89, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We give a detailed description of the measurement of the W boson mass, MW, performed on an integrated luminosity of 4.3 fb super(-1), which is based on similar techniques as used for our previous ...measurement done on an independent data set of 1 fb super(-1) of data. The data were collected using the DO detector at the Fermilab Tevatron Collider. This data set yields 1.68 x 10 super(6) W arrow right ev candidate events. We measure the mass using the transverse mass, electron transverse momentum, and missing transverse energy distributions. The MW measurements using the transverse mass and the electron transverse momentum distributions are the most precise of these three and are combined to give MW = 80.367 + or - 0.013(stat) + or - 0.022(syst) GeV = 80. 367 + or - 0.026 GeV. When combined with our earlier measurement on 1 fb super(-1) of data, we obtain MW = 80.375 + or - 0.023 GeV.
We present a measurement of the fundamental parameter of the standard model, the weak mixing angle sin2θℓeff which determines the relative strength of weak and electromagnetic interactions, in ...pp¯→Z/γ*→e+e- events at a center of mass energy of 1.96 TeV, using data corresponding to 9.7 fb-1 of integrated luminosity collected by the D0 detector at the Fermilab Tevatron. The effective weak mixing angle is extracted from the forward-backward charge asymmetry as a function of the invariant mass around the Z boson pole. The measured value of sin2θℓeff=0.23147±0.00047 is the most precise measurement from light quark interactions to date, with a precision close to the best LEP and SLD results.
We present various properties of the production of the X ( 3872 ) and ψ ( 2S ) states based on 10.4 fb-1 collected by the D0 experiment in Tevatron p p ¯ collisions at s=1.96 TeV . For both states, ...we measure the nonprompt fraction fNP of the inclusive production rate due to decays of b -flavored hadrons. We find the fNP values systematically below those obtained at the LHC. The fNP fraction for ψ ( 2S ) increases with transverse momentum, whereas for the X ( 3872 ) it is constant within large uncertainties, in agreement with the LHC results. The ratio of prompt to nonprompt ψ ( 2S ) production, ( 1-fNP ) / fNP , decreases only slightly going from the Tevatron to the LHC, but for the X ( 3872 ) , this ratio decreases by a factor of about 3. We test the soft-pion signature of the X ( 3872 ) modeled as a weakly bound charm-meson pair by studying the production of the X ( 3872 ) as a function of the kinetic energy of the X ( 3872 ) and the pion in the X ( 3872 ) π center-of-mass frame. For a subsample consistent with prompt production, the results are incompatible with a strong enhancement in the production of the X ( 3872 ) at the small kinetic energy of the X ( 3872 ) and the π in the X ( 3872 ) π center-of-mass frame expected for the X+soft -pion production mechanism. For events consistent with being due to decays of b hadrons, there is no significant evidence for the soft-pion effect, but its presence at the level expected for the binding energy of 0.17 MeV and the momentum scale Λ =M ( π ) is not ruled out.
SPD Range (Muon) System Abazov, V. M.; Alexeev, G. D.; Golovanov, G. A. ...
Physics of particles and nuclei,
07/2021, Letnik:
52, Številka:
4
Journal Article
Recenzirano
The range system (RS) is one of the essential detectors of the spin physics detector (SPD) which is currently under preparation for the second interaction point of the NICA collider. RS provides ...identification of muons and can also be used as a coarse hadronic calorimeter. The SPD range system design and geometry modeling are presented as well as the main results of RS prototype tests.
We study the production of the exotic charged charmonium-like state $Z_c^{\pm}(3900)$ in $p \bar p$ collisions through the sequential process $\psi(4260) \rightarrow Z_c^{\pm}(3900) \pi^{\mp}$, ...$Z_c^{\pm}(3900) \rightarrow J/\psi \pi^{\pm}$. Using the subsample of candidates originating from semi-inclusive weak decays of $b$-flavored hadrons, we measure the invariant mass and natural width to be $M=3902.6^{+5.2}_{-5.0}{\rm \thinspace (stat)}^{+3.3}_{-1.4}{\rm \thinspace (syst)}$ MeV and $\Gamma=32 ^{+28}_{-21}{\rm \thinspace (stat)} ^{+26}_{-7}{\rm \thinspace (syst)}$ MeV, respectively. We search for prompt production of the $Z_c^{\pm}(3900)$ through the same sequential process. No significant signal is observed, and we set an upper limit of 0.66 at the 95\% credibility level on the ratio of prompt production to the production via $b$-hadron decays. The study is based on $10.4~\rm{fb^{-1}}$ of $p \overline p $ collision data collected by the D0 experiment at the Fermilab Tevatron collider.
Here, we present evidence for the exotic charged charmoniumlike state Z±c(3900) decaying to J/ψπ± in semi-inclusive weak decays of b-flavored hadrons. The signal is correlated with a parent J/ψπ+π- ...system in the invariant-mass range 4.2–4.7 GeV that would include the exotic structure Y(4260). The study is based on 10.4 fb-1 of pp¯ collision data collected by the D0 experiment at the Fermilab Tevatron collider.
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