D0 Data Research Articles

Silicate glass fracture surface energy calculated from crystal structure and bond-energy data

We present a novel method to predict the fracture surface energy, γ, of isochemically crystallizing silicate glasses using readily available crystallographic structure data of their crystalline counterpart and tabled diatomic chemical bond energies, D0. The method assumes that γ equals the fracture surface energy of the most likely cleavage plane of the crystal. Calculated values were in excellent agreement with those calculated from glass density, network connectivity and D0 data in earlier work. This finding demonstrates a remarkable equivalence between crystal cleavage planes and glass fracture surfaces.

A computational inspection of the dissociation energy of mid-sized organic dimers.

The gas-phase value of the dissociation energy (D0) is a key parameter employed in both experimental and theoretical descriptions of noncovalent complexes. The D0 data were obtained for a set of mid-sized organic dimers in their global minima which was located using geometry optimizations that applied ample basis sets together with either the conventional second-order Møller-Plesset (MP2) method or several dispersion-corrected density-functional theory (DFT-D) schemes. The harmonic vibrational zero-point (VZP) and deformation energies from the MP2 calculations were combined with electronic energies from the coupled cluster theory with singles, doubles, and iterative triples [CCSD(T)] extrapolated to the complete basis set (CBS) limit to estimate D0 with the aim of inspecting values that were most recently measured, and an analogous comparison was performed using the DFT-D data. In at least one case (namely, for the aniline⋯methane cluster), the D0 estimate that employed the CCSD(T)/CBS energies differed from experiment in the way that could not be explained by a possible deficiency in the VZP contribution. Curiously, one of the DFT-D schemes (namely, the B3LYP-D3/def2-QZVPPD) was able to reproduce all measured D0 values to within 1.0 kJ/mol from experimental error bars. These findings show the need for further measurements and computations of some of the complexes. In order to facilitate such studies, the physical nature of intermolecular interactions in the investigated dimers was analyzed by means of the DFT-based symmetry-adapted perturbation theory.

Study of the normalized transverse momentum distribution of W bosons produced in pp¯ collisions at s=1.96 TeV

We present a study of the normalized transverse momentum distribution of $W$ bosons produced in $p \bar p$ collisions, using data corresponding to an integrated luminosity of 4.35 fb$^{-1}$ collected with the D0 detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96$ TeV. The measurement focuses on the transverse momentum region below 15 GeV, which is of special interest for electroweak precision measurements; it relies on the same detector calibration methods which were used for the precision measurement of the $W$ boson mass. The measured distribution is compared to different QCD predictions and a procedure is given to allow the comparison of any further theoretical models to the D0 data.

Impact of dijet and D-meson data from 5.02 TeV p+Pb collisions on nuclear PDFs

We discuss the new constraints on gluon parton distribution function (PDF) in lead nucleus, derivable with the Hessian PDF reweighting method from the 5.02 TeV p+Pb measurements of dijet (CMS) and D0-meson (LHCb) nuclear modification ratios. The impact is found to be significant, placing stringent constraints in the mid- and previously unconstrained small-x regions. The CMS dijet data confirm the existence of gluon anti-shadowing and the onset of small-x shadowing, as well as reduce the gluon PDF uncertainties in the larger-x region. The gluon constraints from the LHCb D0 data, reaching down to x ∼ 10−5 and derived in a NLO perturbative QCD approach, provide a remarkable reduction of the small-x uncertainties with a strong direct evidence of gluon shadowing. Furthermore, we find a good description of the data even down to zero D0-meson transverse momentum within a purely DGLAP-based approach without a need for imposing any non-linear effects. Importantly, the constraints obtained from the dijet and D0 data are mutually fully consistent, supporting the universality of nuclear PDFs in hard-scattering processes.

Associated production of J/ψ and mesons and the prospects to observe a new hypothetical tetraquark state

We propose a new mechanism for prompt simultaneous production of J/ψ and ϒ mesons in high energy hadronic collisions. The process is considered as a perturbative production of B c ( * ) mesons g + g → B c ( * ) + B c ( * ) followed by a long-distance final state interaction that rearranges the quarks to form J/ψ and ϒ mesons. Passing from B c ( * ) + B c ( * ) configuration to J/ψ+ ϒ configuration may proceed via a hypothetical resonance state, the tetraquark. The goal of this work is to examine whether the respective cross section is large enough to encourage a direct search for the tetraquark at the LHC conditions (yes), and whether this hypothesis can help to explain recent D0 data without assigning an unusually low value to σeff in the double parton scattering mechanism (no).

Higgs Boson Studies at the Tevatron

We present the combination of searches for the Standard Model Higgs boson at a center-of-mass energy of s=1.96 TeV, using the full Run 2 dataset collected with the CDF and D0 detectors at the Fermilab Tevatron collider. We also present combined measurements of Higgs Boson production cross sections, branching ratios, and couplings to fermions and bosons. Finally, we present tests of different spin and parity hypotheses for a particle H of mass 125 GeV produced in association with a vector boson and decaying into a pair of b quarks, and place constraints on such hypotheses using the D0 data.

Condensate-enclosed chiral-bag model of the proton and pp elastic scattering at LHC 13 TeV

Our investigation of high energy [Formula: see text] and [Formula: see text] elastic scattering over the last ten years has led us to consider that the proton has three regions: (i) an outer region consisting of a quark–antiquark [Formula: see text] condensate ground state (also described as quark–antiquark outer cloud), (ii) an inner shell of topological (geometrical) baryonic charge of size [Formula: see text] 0.44 fm, and (iii) a core of size [Formula: see text] 0.2 fm, where the three valence quarks of a proton with baryonic charges are confined. The proton structure that has emerged leads to four main elastic scattering processes in [Formula: see text] scattering. The first process (which gives rise to diffraction scattering) is described by a profile function. The second process involves multiple [Formula: see text]-exchanges. The third process in [Formula: see text] scattering is quark–quark scattering via gluon–gluon interaction. The fourth process — which appears for the first time in our investigation of [Formula: see text] scattering — is a glancing collision at the boundary of a proton with that of the other proton. To describe quantitatively the four processes, their parameters have to be determined. For this purpose, we investigate: (i) [Formula: see text] 7 TeV [Formula: see text] measured by the TOTEM Collaboration and (ii) [Formula: see text] 1.96 TeV [Formula: see text] measured by the D0 Collaboration. Once the parameters are satisfactorily obtained, we calculate [Formula: see text] [Formula: see text] at 7 TeV and compare with the TOTEM data. We also calculate [Formula: see text] [Formula: see text] at 1.96 TeV and compare with the D0 data. We then predict [Formula: see text] elastic [Formula: see text] at 13 TeV which will soon be measured at LHC by the TOTEM Collaboration. This measurement will establish how well we have predicted the 13 TeV [Formula: see text] and determined the structure of the proton.

Heavy flavor at the Tevatron

The CDF and D0 experiments at the Tevatron proton-antiproton collider have pioneered and established the role of hadron collisions in exploring flavor physics through a broad program that continues to offer competitive results. I report on latest results in the flavor sector obtained using the whole CDF and D0 data sets corresponding to ∼ 10 fb−1 of integrated luminosity; including B-mesons spectroscopy and production asymmetries, flavor specific decay bottom-strange mesons lifetime. I also present measurements of direct and indirect CP violation in bottom and charm meson decays.

Application of the principle of maximum conformality to the top-quark charge asymmetry at the LHC

The Principle of Maximum Conformality (PMC) provides a systematic and process-independent method to derive renormalization scheme- and scale- independent fixed-order pQCD predictions. In Ref.\cite{pmc3}, we studied the top-quark charge asymmetry at the Tevatron. By applying the PMC, we have shown that the large discrepancies for the top-quark charge asymmetry between the Standard Model estimate and the CDF and D0 data are greatly reduced. In the present paper, with the help of the Bernreuther-Si program, we present a detailed PMC analysis on the top-quark pair production up to next-to-next-to-leading order level at the LHC. After applying PMC scale setting, the pQCD prediction for the top-quark charge asymmetry at the LHC has very small scale uncertainty; e.g., $A_{\rm C}|_{\rm 7 TeV;PMC} =\left(1.15^{+0.01}_{-0.03}\right)\%$, $A_{\rm C}|_{\rm 8 TeV;PMC} =\left(1.03^{+0.01}_{+0.00}\right)\%$, and $A_{\rm C}|_{\rm 14 TeV;PMC} =\left(0.62^{+0.00}_{-0.02}\right)\%$. The corresponding predictions using conventional scale setting are: $A_{\rm C}|_{\rm 7 TeV;Conv.} =\left(1.23^{+0.14}_{-0.14}\right)\%$, $A_{\rm C}|_{\rm 8 TeV;Conv.} =\left(1.11^{+0.17}_{-0.13}\right)\%$, and $A_{\rm C}|_{\rm 14 TeV;Conv.} =\left(0.67^{+0.05}_{-0.05}\right)\%$. In these predictions, the scale errors are predicted by varying the initial renormalization and factorization scales in the ranges $\mu^{\rm init}_r\in[m_t/2,2m_t]$ and $\mu_f\in[m_t/2,2m_t]$. The PMC predictions are also in better agreement with the available ATLAS and CMS data. In addition, we have calculated the top-quark charge asymmetry assuming several typical cuts on the top-pair invariant mass $M_{t\bar{t}}$. For example, assuming $M_{t\bar{t}}>0.5 ~ {\rm TeV}$ and $\mu_f=\mu^{\rm init}_r =m_t$, we obtain $A_{\rm C}|_{\rm 7 TeV;PMC}=2.67\%$, $A_{\rm C}|_{\rm 8 TeV;PMC}=2.39\%$, and $A_{\rm C}|_{\rm 14 TeV;PMC}=1.28\%$.

ALICE Collaboration

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%.

$W$ boson mass measurement with D0 data

$W$ boson mass measurement with D0 data

Statistical issues in the parton distribution analysis of the Tevatron jet data

We analyse a tension between the D0 and CDF inclusive jet data and the perturbative QCD calculations, which are based on the ABKM09 and ABM11 parton distribution functions (PDFs) within the nuisance parameter framework. Particular attention is paid on the uncertainties in the nuisance parameters due to the data fluctuations and the PDF errors. We show that with account of these uncertainties the nuisance parameters do not demonstrate a statistically significant excess. A statistical bias of the estimator based on the nuisance parameters is also discussed.

Muon reconstruction and identification with the Run II D0 detector

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%.

Measurement of theZZproduction cross section and search for the standard model Higgs boson in the four lepton final state inpp¯collisions

We present a measurement of Z boson pair production in ppbar collisions at 1.96 TeV with 9.6 fb-1 to 9.8fb-1 of D0 data. We examine the final states with four electrons, two electrons plus two muons, and four muons. Based on selected data, the measured cross section in the mass region M(Z/gamma*) > 30 GeV is sigma(ppbar to Z/gamma* Z/gamma*)= 1.26 ^{+0.44}_{-0.36} (stat) ^{+0.17}_{-0.15} (syst) +/- 0.08 (lumi) pb; after correcting for the expected ratio of sigma(ppbar to Z/gamma* Z/gamma*) to sigma(ppbar to ZZ), we derive a cross section for ppbar to ZZ production of 1.05 ^{+0.37}_{-0.30} (stat) ^{+0.14}_{-0.12} (syst) +/- 0.06 (lumi) pb. This result is combined with a previous result from the ZZ to two charged leptons plus two neutrinos channel resulting in a combined ppbar to ZZ cross section measurement of 1.32 ^{+0.29}_{-0.25} (stat) +/- 0.12 (syst) +/- 0.04 (lumi)} pb. These measurements are consistent with the standard model expectation of 1.43 \pm 0.10 pb. We extend this analysis to search for the standard model (SM) Higgs boson between 115 and 200 GeV. At a Higgs boson mass of 125 GeV, we expect to set a limit of 43 times the SM expectation at 95% C.L., and set a limit of 42 times the SM expectation at 95% C.L.

Elasticpp¯scattering amplitude at 1.8 TeV and determination of total cross section

The data on $\mathrm{p}\overline{\mathrm{p}}$ elastic scattering at 1.8 and 1.96 TeV are analyzed in terms of real and imaginary amplitudes, in a treatment with high accuracy, covering the whole $t$ range, and satisfying the expectation of dispersion relation for amplitudes and for slopes. A method is introduced for the determination of the total cross section and the other forward scattering parameters and to check compatibility of E-710, CDF, and the recent D0 data. Slopes ${B}_{R}$ and ${B}_{I}$ of the real and imaginary amplitudes, treated as independent quantities, influence the amplitudes in the whole $t$ range and are important for the determination of the total cross section. The amplitudes are fully constructed, and a prediction is made of a marked dip in $d\ensuremath{\sigma}/dt$ in the $|t|$ range $3--5\text{ }\text{ }{\mathrm{GeV}}^{2}$ due to the universal contribution of the process of three-gluon exchange.

Three Pomerons versus D0 and TOTEM data

This paper highlights the predictive power of the three-component Pomeron model designed by the authors ten years ago, with a partial account of the multiplicity of Pomerons in QCD. The model is put to the test by comparing its predictions with the recent data from the D0 and TOTEM collaborations at 1.96 and 7 TeV, respectively. We also compare model predictions for inelastic cross sections to experimental measurements by the TOTEM, CMS, ALICE, and ATLAS collaborations. It is shown that the D0 data are perfectly predicted by the model. Total, elastic, and inelastic cross-section predictions are in agreement with the measurements by the TOTEM, CMS, ALICE, and ATLAS collaborations. Differential cross-section data at 7 TeV show slight disagreement with predictions of the model in the high-$t$ region. Discussions on the origin of the disagreement and conclusions are presented.

Application of the principle of maximum conformality to the top-quark forward-backward asymmetry at the Tevatron

The renormalization scale uncertainty can be eliminated by the Principle of Maximum Conformality (PMC) in a systematic scheme-independent way. Applying the PMC for the $t\bar{t}$-pair hadroproduction at the NNLO level, we have found that the total cross-sections $\sigma_{t\bar{t}}$ at both the Tevatron and LHC remain almost unchanged when taking very disparate initial scales $\mu^{\rm init}_R$ equal to $m_t$, $10\,m_t$, $20\,m_t$ and $\sqrt{s}$, which is consistent with renormalization group invariance. As an important new application, we apply PMC scale-setting to study the top-quark forward-backward asymmetry. We observe that the more convergent perturbative series after PMC scale-setting leads to a more accurate top-quark forward-backward asymmetry. The resulting PMC prediction on the asymmetry is also free from the initial renormalization scale-dependence. Because the NLO PMC scale has a dip behavior for the $(q\bar{q})$-channel at small subprocess collision energies, the importance of this channel to the asymmetry is increased. We observe that the asymmetries $A_{FB}^{t\bar{t}}$ and $A_{FB}^{p\bar{p}}$ at the Tevatron will be increased by 42% in comparison to the previous estimates obtained by using conventional scale-setting; i.e. we obtain $A_{FB}^{t\bar{t},{\rm PMC}} \simeq 12.5%$ and $A_{FB}^{p\bar{p},{\rm PMC}} \simeq 8.28%$. Moreover, we obtain $A_{FB}^{t\bar{t},{\rm PMC}}(M_{t\bar{t}}>450 \;{\rm GeV}) \simeq 35.0%$. These predictions have a $1\sigma$-deviation from the present CDF and D0 measurements; the large discrepancies of the top-quark forward-backward asymmetry between the Standard Model estimate and the CDF and D0 data are thus greatly reduced.

Mass dependent top forward–backward asymmetry in the effective Lagrangian approach: Addendum to “Model independent analysis of the forward–backward asymmetry of top quark production at the Tevatron”

Recently the CDF and the D0 Collaborations presented the data on the top forward–backward (FB) asymmetry AFB as functions of Mtt¯ and Δy≡yt−yt¯. We study these observables in the effective Lagrangian approach with dimension-6 qq¯tt¯ contact interactions, and compare with the CDF and D0 data. When we stay within the validity region of the effective Lagrangian approach, the mass dependent top FB asymmetry turns out to be smaller than the CDF data, more than 2-σ away. If this discrepancy remains in the future data with better statistics, it would imply that the effective Lagrangian approach is not adequate for the top FB asymmetry, and a new physics scale around a few hundred GeV in the t- or u-channel may be responsible for the observed top FB asymmetry.

Bounds on an Anomalous Dijet Resonance inW+jetsProduction inpp¯Collisions ats=1.96 TeV

We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W boson in data corresponding to an integrated luminosity of 4.3 fb(-1) collected with the D0 detector at √s = 1.96 TeV. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to 170 GeV/c(2). The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb production cross section at 145 GeV/c(2) is 8×10(-6).

Four-jet production at LHC and Tevatron in QCD

We demonstrate that in the back-to-back kinematics the production of four jets in the collision of two partons is suppressed in the leading log approximation of pQCD, compared to the \^Ehard processes involving the collision of four partons. We derive the basic equation for four-jet production in QCD in terms of the convolution of generalized two-parton distributions of colliding hadrons in the momentum space representation. Our derivation leads to geometrical approach in the impact parameter space close to that suggested within the parton model and used before to describe the four-jet production. We develop the independent parton approximation to the light-cone wave function of the proton. Comparison with the CDF and D0 data shows that the independent parton approximation to the light-cone wave function of the proton is insufficient to explain the data. We argue that the data indicate the presence of significant multiparton correlations in the light-cone wave functions of colliding protons.