D0 Measurement Research Articles

Measurement of nonprompt and prompt D0 azimuthal anisotropy in Pb-Pb collisions at √SNN = 5.02 TeV

Heavy quarks are primarily produced via initial hard scatterings, and thus carry information about the early stages of the Quark-Gluon Plasma (QGP). Measurements of the azimuthal anisotropy of the final-state heavy flavor hadrons provide information about the initial collision geometry, its fluctuation, and more importantly, the mass dependence of energy loss in QGP. Due to the larger bottom quark mass as compared to the charm quark mass, separate measurements of charm and bottom hadron azimuthal anisotropy can shed new light on understanding the dependence of the heavy quark and medium interaction. Because of the high branching ratio and large D0 mass, measurements of D0 meson coming from bottom hadron decay (nonprompt D0) can cover a broad kinematic range and be a good proxy of the parent bottom hadrons results. In this talk, we report on the prompt D0 and the first nonprompt D0 measurements of the azimuthal anisotropy elliptic (v2) and triangular (v3) coefficients of nonprompt D0 in PbPb collisions at √SNN = 5.02 TeV. The measurements are performed as functions of transverse momentum pT, in three centrality classes, from central to midcentral collisions. Compared to the prompt D0 results, the nonprompt D0 v2 flow coefficients are systematically lower but have a similar dependence on pT and centrality. A non-zero v3 coefficient of the nonprompt D0 is observed. The obtained results are compared with theoretical predictions. The comparison could provide new constraints on the theoretical description of the interaction between heavy quarks and the medium.

Bonding, Thermodynamics, and Dissociation Dynamics of NiO+ and NiS+ Determined by Photofragment Imaging and Theory.

We use photofragment ion imaging and ab initio calculations to determine the bond strength and photodissociation dynamics of the nickel oxide (NiO+) and nickel sulfide (NiS+) cations. NiO+ photodissociates broadly from 20350 to 32000 cm-1, forming ground state products Ni+(2D) + O(3P) below ∼29000 cm-1. Above this energy, Ni+(4F) + O(3P) products become accessible and dominate over the ground state channel. In certain images, product spin-orbit levels are resolved, and spin-orbit propensities are determined. Image anisotropy and the results of MRCI calculations suggest NiO+ photodissociates via a 3 4Σ- ← X 4Σ- transition above the Ni+(4F) threshold and via 3 4Σ-, 2 4Σ-, and/or 2 4Π and 3 4Π excited states below the 4F threshold. The photodissociation spectrum of NiS+ from 19900 to 23200 cm-1 is highly structured, with ∼12 distinct vibronic peaks, each containing underlying substructure. Above 21600 cm-1, the Ni+(2D5/2) + S(3P) and Ni+(2D3/2) + S(3P) product spin-orbit channels compete, with a branching ratio of ∼2:1. At lower energy, Ni+(2D5/2) is formed exclusively, and S(3P2) and S(3P1) spin-orbit channels are resolved. MRCI calculations predict the ground state of NiS+ to be one of two nearly degenerate states, the 1 4Σ- and 1 4Δ. Based on images and spectra, the ground state of NiS+ is assigned as 4Δ7/2, with the 1 4Σ3/2- and 1 4Σ1/2- states 81 ± 30 and 166 ± 50 cm-1 higher in energy, respectively. The majority of the photodissociation spectrum is assigned to transitions from the 1 4Δ state to two overlapping, predissociative excited 4Δ states. Our D0 measurements for NiO+ (D0 = 244.6 ± 2.4 kJ/mol) and NiS+ (D0 = 240.3 ± 1.4 kJ/mol) are more precise and closer to each other than previously reported values. Finally, using a recent measurement of D0(NiS), we derive a more precise value for IE (NiS): 8.80 ± 0.02 eV (849 ± 1.7 kJ/mol).

Odderon Exchange from Elastic Scattering Differences between pp and pp[over ¯] Data at 1.96TeV and from pp Forward Scattering Measurements.

We describe an analysis comparing the pp[over ¯] elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96TeV to that in pp collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13TeV using a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of sqrt[s]=1.96 TeV, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the pp cross section. The two data sets disagree at the 3.4σ level and thus provide evidence for the t-channel exchange of a colorless, C-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same C-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering for which the significance is between 3.4σ and 4.6σ. The combined significance is larger than 5σ and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.

Measurement of the Effective Weak Mixing Angle in pp[over ¯]→Z/γ^{*}→ℓ^{+}ℓ^{-} Events.

We present a measurement of the effective weak mixing angle parameter sin^{2}θ_{eff}^{ℓ} in pp[over ¯]→Z/γ^{*}→μ^{+}μ^{-} events at a center-of-mass energy of 1.96TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb^{-1} of integrated luminosity. The measured value of sin^{2}θ_{eff}^{ℓ}[μμ]=0.23016±0.00064 is further combined with the result from the D0 measurement in pp[over ¯]→Z/γ^{*}→e^{+}e^{-} events, resulting in sin^{2}θ_{eff}^{ℓ}[comb]=0.23095±0.00040. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the Z/γ^{*} to light quarks.

Combination of D0 measurements of the top quark mass

We present a combination of measurements of the top quark mass by the D0 experiment in the lepton+jets and dilepton channels. We use all the data collected in Run I (1992--1996) at $\sqrt s=1.8$ TeV and Run II (2001--2011) at $\sqrt s=1.96$ TeV of the Tevatron $p \bar{p}$ collider, corresponding to integrated luminosities of 0.1 fb$^{-1}$ and 9.7 fb$^{-1}$, respectively. The combined result is: $m_t = 174.95 \pm0.40\,{\rm(stat)} \pm 0.64\,{\rm(syst)}\,{\rm{GeV}}=174.95 \pm 0.75 \, {\rm{GeV}}$.

Complete Study of Hadroproduction of a ϒ Meson Associated with a Prompt J/ψ.

We present the first complete study of ϒ and prompt J/ψ production from single-parton scattering, including the complete O(α_{S}^{6}) color-singlet contribution, the O(α_{S}^{2}α^{2}) electroweak contribution, and the complete nonrelativistic S-wave and P-wave color-octet contribution as well as the feeddown contribution. Our study was motivated by the recent evidence reported by the D0 Collaboration of prompt J/ψ and ϒ simultaneous production at the Tevatron. With our complete evaluation, we are able to refine the determination of the double-parton scattering contribution made by the D0 Collaboration. We find that the effective cross section characterizing the importance of double-parton scatterings is σ_{eff}≤8.2 mb at 68%confidence level from the D0 measurement.

Top quark pair production

These proceedings discuss D0 measurements of the top pair differential cross section and forward-backward asymmetry. All measurements are consistent with the predictions based on the standard model.

Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element V_{tb}.

We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb^{-1} per experiment. The t-channel cross section is measured to be σ_{t}=2.25_{-0.31}^{+0.29} pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in σ_{s+t}=3.30_{-0.40}^{+0.52} pb, without assuming the standard model value for the ratio σ_{s}/σ_{t}. The resulting value of the magnitude of the top-to-bottom quark coupling is |V_{tb}|=1.02_{-0.05}^{+0.06}, corresponding to |V_{tb}|>0.92 at the 95% C.L.

Mixing asymmetries inBmeson systems, the D0 like-sign dimuon asymmetry, and generic new physics

The measurement of a large like-sign dimuon asymmetry $A^b_{SL}$ by the D0 experiment at the Tevatron departs noticeably from Standard Model expectations and it may be interpreted as a hint of physics beyond the Standard Model contributing to $\Delta B\neq 0$ transitions. In this work we analyse how the natural suppression of $A^b_{SL}$ in the SM can be circumvented by New Physics. We consider generic Standard Model extensions where the charged current mixing matrix is enlarged with respect to the usual $3\times 3$ unitary Cabibbo-Kobayashi-Maskawa matrix, and show how, within this framework, a significant enhancement over Standard Model expectations for $A^b_{SL}$ is easily reachable through enhancements of the semileptonic asymmetries $A^d_{SL}$ and $A^s_{SL}$ of both $B^0_d$ - $\bar B^0_d$ and $B^0_s$ - $\bar B^0_s$ systems. Despite being insufficient to reproduce the D0 measurement, such deviations from SM expectations may be probed by the LHCb experiment.

Observation of s-channel production of single top quarks at the Tevatron.

We report the first observation of single-top-quark production in the s channel through the combination of the CDF and D0 measurements of the cross section in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb(-1) per experiment. The measured cross section is σ(s) = 1.29(-0.24)(+0.26) pb. The probability of observing a statistical fluctuation of the background to a cross section of the observed size or larger is 1.8 × 10(-10), corresponding to a significance of 6.3 standard deviations for the presence of an s-channel contribution to the production of single-top quarks.

Combination of CDF and D0W-Boson mass measurements

We summarize and combine direct measurements of the mass of the $W$ boson in $\sqrt{s} = 1.96 \text{TeV}$ proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to $2.2 \mathrm{fb}^{-1}$ of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to $4.3 \mathrm{fb}^{-1}$ of integrated luminosity. The resulting Tevatron average for the mass of the $W$ boson is $\MW = 80\,387 \pm 16 \text{MeV}$. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of $\MW = 80\,385 \pm 15 \text{MeV}$.

The effect of d0 reference value on a neutron diffraction study of residual stress in a γ/γ′ nickel-base superalloy

A nickel-base superalloy sub-scale disc has been studied using neutron diffraction to characterise the residual stress distribution following heat treatment. Strain has been calculated using measured neutron diffraction d-spacings in combination with d0 reference values obtained using three distinct methods, namely, measurement of a stress-free cube, a sin2 ψ characterisation (used independently and as a correction factor), and an axial stress balance. In addition, data obtained using the contour method have been included since it allows comparison of diffraction-based data to a technique that does not require a d0 value. In terms of residual stress, agreement between all d0 measurement techniques and the contour method was high, with the exception being those made using the sin2 ψ technique. An offset of approximately 350 MPa was observed in these data, and a possible systematic error was ascribed to a unique diffraction characteristic of a γ/ γ′ nickel-base superalloy. A global d0 value obtained using a stress balance or stress-free cube was found to be reliable throughout the sample bulk in cases where thermal processing was carried out at a slow rate, such as ageing. However, d0 differences equivalent to 400 µε were observed between central and surface regions when a global d0 was applied to a water-quenched sample.

Eliminating the Renormalization Scale Ambiguity for Top-Pair Production Using the Principle of Maximum Conformality

It is conventional to choose a typical momentum transfer of the process as the renormalization scale and take an arbitrary range to estimate the uncertainty in the QCD prediction. However, predictions using this procedure depend on the renormalization scheme, leave a nonconvergent renormalon perturbative series, and moreover, one obtains incorrect results when applied to QED processes. In contrast, if one fixes the renormalization scale using the principle of maximum conformality (PMC), all nonconformal {β(i)} terms in the perturbative expansion series are summed into the running coupling, and one obtains a unique, scale-fixed, scheme-independent prediction at any finite order. The PMC scale μ(R)(PMC) and the resulting finite-order PMC prediction are both to high accuracy independent of the choice of initial renormalization scale μ(R)(init), consistent with renormalization group invariance. As an application, we apply the PMC procedure to obtain next-to-next-to-leading-order (NNLO) predictions for the tt-pair production at the Tevatron and LHC colliders. The PMC prediction for the total cross section σ(tt) agrees well with the present Tevatron and LHC data. We also verify that the initial scale independence of the PMC prediction is satisfied to high accuracy at the NNLO level: the total cross section remains almost unchanged even when taking very disparate initial scales μ(R)(init) equal to m(t), 20m(t), and √s. Moreover, after PMC scale setting, we obtain A(FB)(tt)≃12.5%, A(FB)(pp)≃8.28% and A(FB)(tt)(M(tt)>450 GeV)≃35.0%. These predictions have a 1σ deviation from the present CDF and D0 measurements; the large discrepancy of the top quark forward-backward asymmetry between the standard model estimate and the data are, thus, greatly reduced.

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.

Combination of CDF and D0 measurements of theWboson helicity in top quark decays

We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.7 - 5.4 fb^-1 of ppbar collisions collected during Run II of the Fermilab Tevatron Collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f0) and right-handed (f+) helicities, we find f0 = 0.722 \pm 0.081 [\pm 0.062 (stat.) \pm 0.052 (syst.)] and f+ = -0.033 \pm 0.046 [\pm 0.034 (stat.) \pm 0.031 (syst.)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f0 = 0.682 \pm 0.057 [\pm 0.035 (stat.) \pm 0.046 (syst.)] and f+ = -0.015\pm0.035 [\pm 0.018 (stat.) \pm 0.030 (syst.)]. The results are consistent with standard model expectations.

Plasma Concentration of ST2, the IL33 Receptor, At Initiation of Graft Versus Host Disease Therapy Predicts Day 28 Response and Day 180 Survival Post-Treatment

Abstract 152Acute graft-versus-host disease (GVHD) is the primary limitation of allogeneic hematopoietic cell transplantation (HCT). Current diagnostic tests do not predict a patient's response to therapy, particularly at GVHD onset, when risk-stratification is most beneficial. We hypothesized that biomarkers discovered with an intact proteomic analysis system (IPAS) approach that we have previously described (Paczesny et al. 2010) will discriminate between therapy responsive (resolution or improvement of GVHD by day (D) 28 post-therapy initiation) and unresponsive (absence of complete or partial response) patients and predict survival in patients receiving GVHD therapy.We first performed an IPAS comparing pooled plasma taken at D16 ± 5 post-therapy from 10 responders (R) and 10 non-responders (NR). Ten candidate biomarkers with an NR/R ratio of > 1.5 in the IPAS were measurable by ELISA. We therefore measured concentrations in the 20 individual plasma aliquots. Five were significantly increased in NR vs. R, with an area under the receiver operator characteristic curve of ≥ 0.85 (ST2, IL1sRII, MIF, LYVE, and Lipocalin). These were then measured at therapy initiation (D0), with 6 previously validated diagnostic biomarkers of GVHD (IL2Rα, TNFR1, HGF, IL8, Elafin, a skin-specific marker, and Reg3α, a gut-specific marker) in plasma samples from a validation set of 381 patients with acute GVHD grade 1–4 at onset and treated with systemic steroids at the University of Michigan from 2000 to 2011. Preliminary analyses (not shown) determined that D0 measurements predicted D28 non-response and D180 OS. HLA match (match vs. mismatched; Odds Ratio (OR) 1.5, p = 0.07), conditioning intensity (full vs. reduced; OR 1.7, p = 0.04), and GVHD onset grade (grade 3–4 vs. grade 1–2; OR 2.2, p = 0.001) predicted day 28 non-response in univariate analysis, while age at transplant (≥ 55 years vs. < 55 years), donor (unrelated vs. related), and stem cell source (peripheral blood vs. bone marrow/cord) did not. After adjustment for the 3 clinical characteristics which predicted D28 response, multivariate analysis of the 11 protein concentrations showed that 3 predicted D28 response (ST2, p = 0.001; IL1sRII, p = 0.07; and IL8, p = 0.03) and 7 predicted post-therapy D180 OS (ST2, p = 0.003; IL1sRII, p = 0.07; IL8, p = 0.05; Elafin, p = 0.06; MIF, p = 0.04; TNFR, p = 0.03; and Reg3α, p = 0.002 in gut-GVHD subset). Using logistic regression, we examined the ability of both the 7 biomarkers and ST2 alone to predict for D28 non-response, as ST2 was the most significant marker in all previous analyses. ST2 is the IL33 receptor, a member of the IL1/ Toll-like receptor superfamily, which promotes a Th2-type immune response in diseases such as arthritis and asthma (Kakkar et al. 2008). A high biomarker value was defined as a plasma concentration greater than 50% above the median value of the responders’ group. A high panel was defined as having at least 5 of 7 high biomarkers. Patients with high ST2 levels were 2.6 times more likely not to respond to therapy independent of the aforementioned significant clinical characteristics (p < 0.001) while patients with a high panel were only 1.9 times more likely not to respond (p = 0.004). Thus, only ST2 measurement was used for further analyses.Because ST2 concentrations correlated with response, we hypothesized that ST2 would predict D180 non-relapse mortality (NRM), independent of GVHD onset grade, the strongest clinical predictor of NRM (20% for GVHD grade 1–2 vs. 50% for GVHD grade 3–4, Hazard ratio (HR) 3.0, p < 0.001). NRM cumulative incidence curves and HR for the 4 risk categories of low ST2 / grade 1–2, low ST2 / grade 3–4, high ST2 / grade 1–2, and high ST2 / grade 3–4 are shown in Figure 1. Interestingly, patients presenting with high clinical grade and low ST2 had a good prognosis, suggesting that ST2 provides important prognostic information at initiation of therapy above the clinical grade. [Display omitted] In conclusion, soluble ST2, the form measured by ELISA, is a decoy receptor that drives the Th2 phenotype toward Th1, a mechanism by which it may act in the pathophysiology of resistant GVHD. ST2 concentrations obtained at initiation of GVHD therapy significantly enhance the accuracy of outcome prediction independent of GVHD grade. Measurement of ST2 may allow for early identification of patients at risk for subsequent non-response and mortality, and may provide a promising target for novel therapeutic interventions. Disclosures:No relevant conflicts of interest to declare.

Effect of spatial variation of stress-free lattice spacings on measured residual stresses

When neutron diffraction is used to measure residual stresses, estimates of the unstressed lattice spacing ( d0) are often required. These are generally measured on a sample that is considered representative of the component. In the case of welded samples, the possibility of variation in weld shape between the d0 sample and the area where stresses are determined must be taken into account. To assess this, d0 values are measured on an area considered representative of the sample, and then are re-measured on a sample cut from the actual strain measurement plane. The residual stresses are re-calculated with these new d0 values and the results compared to those based on the initial d0 measurement. Methods of estimating these errors are discussed. The errors in residual stress that arise from the spatial variation of d0 values are greater than the commonly reported peak fitting errors. These errors can be estimated and should be included in the reported residual stress measurements. Cutting a d0 sample from the measurement plane makes this a destructive technique.

Anomalous CP-violation in [formula omitted] mixing due to a light spin-one particle

The recent measurement of the like-sign dimuon charge asymmetry in semileptonic b-hadron decays by the D0 Collaboration is about three sigmas away from the standard-model prediction, hinting at the presence of CP-violating new physics in the mixing of Bs mesons. We consider the possibility that this anomalous result arises from the contribution of a light spin-1 particle. Taking into account various experimental constraints, we find that the effect of such a particle with mass below the b-quark mass can yield a prediction consistent with the anomalous D0 measurement within its one-sigma range.

B-meson observables in the maximallyCP-violating MSSM with minimal flavor violation

Additional sources of $CP$ violation in the MSSM may affect $B$-meson mixings and decays, even in scenarios with minimal flavor violation (MFV). We formulate the maximally $CP$-violating and minimally flavor-violating (MCPMFV) variant of the MSSM, which has 19 parameters, including 6 phases that violate $CP$. We then develop a manifestly flavor-covariant effective Lagrangian formalism for calculating Higgs-mediated flavor-changing-neutral-current (FCNC) observables in the MSSM at large $\mathrm{tan}\ensuremath{\beta}$, and analyze within the MCPMFV framework FCNC and other processes involving $B$ mesons. We include a new class of dominant subleading contributions due to nondecoupling effects of the third-generation quarks. We present illustrative numerical results that include effects of the $CP$-odd MCPMFV parameters on Higgs and sparticle masses, the ${B}_{s}$ and ${B}_{d}$ mass differences, and on the decays ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, ${B}_{u}\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\nu}$, and $b\ensuremath{\rightarrow}s\ensuremath{\gamma}$. We use these results to derive illustrative constraints on the MCPMFV parameters imposed by D0, CDF, Belle, and BABAR measurements of $B$ mesons, demonstrating how a potentially observable contribution to the $CP$ asymmetry in the $b\ensuremath{\rightarrow}s\ensuremath{\gamma}$ decay may arise in the MSSM with MCPMFV.

TestingCPTinvariance inBd0–B¯d0andBs0–B¯s0oscillations

Recent CDF and D0 measurements of ${B}_{s}^{0}--{\overline{B}}_{s}^{0}$ mixing make it possible to search for $CP$ violation and test $CPT$ symmetry in a variety of ${B}_{s}$ decays. Considering both coherent ${B}_{d}^{0}{\overline{B}}_{d}^{0}$ decays at the $\ensuremath{\Upsilon}(4S)$ resonance and coherent ${B}_{s}^{0}{\overline{B}}_{s}^{0}$ decays at the $\ensuremath{\Upsilon}(5S)$ resonance, we formulate their time-dependent and time-integrated rates by postulating small $CPT$ violation in ${B}_{d}^{0}--{\overline{B}}_{d}^{0}$ and ${B}_{s}^{0}--{\overline{B}}_{s}^{0}$ oscillations. We show that the opposite-sign dilepton events from either $C$-odd or $C$-even ${B}_{q}^{0}{\overline{B}}_{q}^{0}$ states (for $q=d$ or $s$) can be used to determine or constrain the $CPT$-violating parameter at a super-$B$ factory. The possibility of distinguishing between the effect of $CPT$ violation and that of $\ensuremath{\Delta}B=\ensuremath{-}\ensuremath{\Delta}Q$ transitions is also discussed.