Measurement of the high mass Drell-Yan cross-section and limits on quark electron compositeness scales

The D0 collaboration Abbott, B. ; Abolins, M. ; Abramov, V. ; et al.
Phys.Rev.Lett. 82 (1999) 4769-4774, 1999.
Inspire Record 480590 DOI 10.17182/hepdata.42142

We present a measurement of the Drell-Yan cross section at high dielectron invariant mass using 120/pb of data collected in pbar-p collisions at sqrt(s) = 1.8 TeV by the D0 collaboration during 1992-96. No deviation from standard model expectations is observed. We use the data to set limits on the energy scale of quark-electron compositeness with common constituents. The 95% confidence level lower limits on the compositeness scale vary between 3.3 TeV and 6.1 TeV depending on the assumed form of the effective contact interaction.

1 data table match query

Dielectron production cross section.


Measurement of the $W W$ production cross section in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.Lett. 94 (2005) 151801, 2005.
Inspire Record 1650063 DOI 10.17182/hepdata.42037

A change in estimated integrated luminosity (from 226 pb$^{-1} to 257 pb$^{-1}$ leads to a corrected value for ${\sigma (p \bar p \to Z) \cdot}$Br${(Z \to \tau \tau)}$ of $209\pm13(stat.)\pm16(syst.)\pm13(lum) pb.

1 data table match query

Total cross section for W boson pair production. The second systematic (DSYS) error is due to the uncertainty in the luminosity.


Probing BFKL dynamics in the dijet cross section at large rapidity intervals in $p\bar{p}$ collisions at $\sqrt{s} = 1800$ GeV and 630-GeV

The D0 collaboration Abbott, B. ; Abolins, M. ; Abramov, V. ; et al.
Phys.Rev.Lett. 84 (2000) 5722-5727, 2000.
Inspire Record 511525 DOI 10.17182/hepdata.41510

Inclusive dijet production at large pseudorapidity intervals (delta_eta) between the two jets has been suggested as a regime for observing BFKL dynamics. We have measured the dijet cross section for large delta_eta in ppbar collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic cross section increases strongly with the size of delta_eta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of a_{BFKL}(20GeV)=1.65+/-0.07.

4 data tables match query

Z(P=3) and Z(P=4) are longitudinal momentum fractions of the proton and antiproton, carried by the two interacting partons: Z(P=3,4) = 2*ET(P=3,4)/SQRT(S)*EXP(+-ETARAP)*COSH(DELTA(ETARAP)/2), where ETARAP = (ETARAP(P=3)+ETARAP(P=4))/2,DELTA(ETARAP) = ABS(ETARAP(P=3)-ETARAP(P=4)).

Z(P=3) and Z(P=4) are longitudinal momentum fractions of the proton and antiproton, carried by the two interacting partons: Z(P=3,4) = 2*ET(P=3,4)/SQRT(S)*EXP(+-ETARAP)*COSH(DELTA(ETARAP)/2), where ETARAP = (ETARAP(P=3)+ETARAP(P=4))/2,DELTA(ETARAP) = ABS(ETARAP(P=3)-ETARAP(P=4)).

Z(P=3) and Z(P=4) are longitudinal momentum fractions of the proton and antiproton, carried by the two interacting partons: Z(P=3,4) = 2*ET(P=3,4)/SQRT(S)*EXP(+-ETARAP)*COSH(DELTA(ETARAP)/2), where ETARAP = (ETARAP(P=3)+ETARAP(P=4))/2,DELTA(ETARAP) = ABS(ETARAP(P=3)-ETARAP(P=4)).

More…

Search for top squark pair production in the dielectron channel

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.D 57 (1998) 589-593, 1998.
Inspire Record 427311 DOI 10.17182/hepdata.41662

This report describes the first search for top squark pair production in the channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using 74.9 +- 8.9 pb~-1 of data collected using the D0 detector. A 95% confidence level upper limit on sigma*B is presented. The limit is above the theoretical expectation for sigma*B for this process, but does show the sensitivity of the current D0 data set to a particular topology for new physics.

1 data table match query

Data are extracted from the figure. Sigma*Br.


Search for a fourth generation charge -1/3 quark via flavor changing neutral current decay

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.Lett. 78 (1997) 3818-3823, 1997.
Inspire Record 426498 DOI 10.17182/hepdata.42251

We report on a search for pair production of a fourth generation charge -1/3 quark (b') in pbar p collisions at sqrt(s) = 1.8 TeV at the Fermilab Tevatron using an integrated luminosity of 93 pb^-1. Both quarks are assumed to decay via flavor changing neutral currents (FCNC). The search uses the signatures gamma + 3 jets + mu-tag and 2 gamma + 2 jets. We see no significant excess of events over the expected background. We place an upper limit on the production cross section times branching fraction that is well below theoretical expectations for a b' quark decaying exclusively via FCNC for b' quark masses up to m(Z) + m(b).

3 data tables match query

Cross section times branching fraction for the gamma+3jets channel.

Cross section times branching fraction for the 2gamma+2jets channel.

No description provided.


Search for additional neutral gauge bosons

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Lett.B 385 (1996) 471-478, 1996.
Inspire Record 421554 DOI 10.17182/hepdata.42253

We have searched for a heavy neutral gauge boson, Z ′, using the decay channel Z ′ → ee . The data were collected with the DØ detector at the Fermilab Tevatron during the 1992–1993 p p collider run at s =1.8 TeV from an integrated luminosity of 15±1 pb −1 . Limits are set on the cross section times brancing ratio for the process p p → Z′ → ee as a function of the Z ′ mass. We exclude the existence of a Z ′ of mass less than 490 GeV/c 2 , assuming a Z ′ with the same coupling strengths to quarks and leptons as the standard model Z boson.

1 data table match query

No description provided.


Search for First Generation Scalar and Vector Leptoquarks

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abdesselam, A. ; et al.
Phys.Rev.D 64 (2001) 092004, 2001.
Inspire Record 557085 DOI 10.17182/hepdata.42922

We describe a search for the pair production of first-generation scalar and vector leptoquarks in the eejj and enujj channels by the D0 Collaboration. The data are from the 1992--1996 ppbar run at sqrt{s} = 1.8 TeV at the Fermilab Tevatron collider. We find no evidence for leptoquark production; in addition, no kinematically interesting events are observed using relaxed selection criteria. The results from the eejj and enujj channels are combined with those from a previous D0 analysis of the nunujj channel to obtain 95% confidence level (C.L.) upper limits on the leptoquark pair-production cross section as a function of mass and of beta, the branching fraction to a charged lepton. These limits are compared to next-to-leading-order theory to set 95% C.L. lower limits on the mass of a first-generation scalar leptoquark of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively. For vector leptoquarks with gauge (Yang-Mills) couplings, 95% C.L. lower limits of 345, 337, and 206 GeV/c^2 are set on the mass for beta=1, 1/2, and 0, respectively. Mass limits for vector leptoquarks are also set for anomalous vector couplings.

3 data tables match query

No description provided.

No description provided.

No description provided.


Search for Single Top Quark Production at D0 Using Neural Networks

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abdesselam, A. ; et al.
Phys.Lett.B 517 (2001) 282-294, 2001.
Inspire Record 558406 DOI 10.17182/hepdata.42932

We present a search for electroweak production of single top quarks in $\approx 90$ $pb^{-1}$ of data collected with the DZero detector at the Fermilab Tevatron collider. Using arrays of neural networks to separate signals from backgrounds, we set upper limits on the cross sections of 17 pb for the s-channel process $p\bar{p} \to tb + X$, and 22 pb for the t-channel process $p\bar{p} \to tqb + X$, both at the 95% confidence level.

1 data table match query

No description provided.


Measurement of the $p$ - $\bar{p} \to W \gamma$ + $X$ cross section at $\sqrt{s}$ = 1.96-TeV and $W W \gamma$ anomalous coupling limits

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.D 71 (2005) 091108, 2005.
Inspire Record 679253 DOI 10.17182/hepdata.42778

The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.

1 data table match query

Measured cross section for the electron and muon channels combined.


Measurement of the $p \bar{p} \to WZ + X$ cross-section at $\sqrt{s}$ = 1.96-TeV and limits on WWZ trilinear gauge couplings

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, Maris A. ; et al.
Phys.Rev.D 76 (2007) 111104, 2007.
Inspire Record 761244 DOI 10.17182/hepdata.42722

We present measurements of the process $p\bar{p} \to WZ+X \to \ell^{\prime} \nu_{\ell^{\prime}} \ell \bar{\ell}$ at $\sqrt{s}=1.96$ TeV, where $\ell$ and $\ell^{\prime}$ are electrons or muons. Using 1 fb$^{-1}$ of data from the D0 experiment, we observe 13 candidates with an expected background of $4.5\pm0.6$ events and measure a cross section $\sigma(WZ)=2.7^{+1.7}_{-1.3}$ pb. From the number of observed events and the $Z$ boson transverse momentum distribution, we limit the trilinear $WWZ$ gauge couplings to $-0.17 \le \lambda_Z \le 0.21$ $(\Delta \kappa_Z = 0)$ at the 95% C.L. for a form factor scale $\Lambda=2$ TeV. Further, assuming that $\Delta g^Z_1 = \Delta\kappa_Z$, we find $-0.12 \le \Delta\kappa_Z \le 0.29$ $(\lambda_Z=0)$ at the 95% C.L. These are the most restrictive limits on the $WWZ$ couplings available to date.

1 data table match query

Measured WZ cross section.


Measurement of the ratio of the $p \bar{p} \to W^+ c^-$ jet cross section to the inclusive $p \bar{p} \to W +$ jets cross section

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Lett.B 666 (2008) 23-30, 2008.
Inspire Record 781444 DOI 10.17182/hepdata.42740

We present a measurement of the fraction of inclusive $W$+jets events produced with net charm quantum number $\pm1$, denoted $W$+$c$-jet, in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using approximately 1~fb$^{-1}$ of data collected by the D0 detector at the Fermilab Tevatron Collider. We identify the $W$+jets events via the leptonic $W$ boson decays. Candidate $W$+$c$-jet events are selected by requiring a jet containing a muon in association with a reconstructed $W$ boson and exploiting the charge correlation between this muon and $W$ boson decay lepton to perform a nearly model-independent background subtraction. We measure the fraction of $W$+$c$-jet events in the inclusive $W$+jets sample for jet $p_{T}>20$ GeV and pseudorapidity $|\eta|<2.5$ to be 0.074$\pm0.019$(stat.)$\pm^{0.012}_{0.014}$(syst.), in agreement with theoretical predictions. The probability that background fluctuations could produce the observed fraction of $W$+$c$-jet events is estimated to be $2.5\times 10^{-4}$, which corresponds to a 3.5 $\sigma$ statistical significance.

3 data tables match query

Measured value of the W+ charm jet to W+ jet cross sections for W decay into the (E NU) channel for various jet PT ranges.

Measured value of the W+ charm jet to W+ jet cross sections for W decay into the (MU NU) channel for various jet PT ranges.

Measured value of the W+ charm jet to W+ jet cross sections for W decay into the (LEPTON NU) channel for various jet PT ranges.


Measurement of the ratios of the Z/gamma* + >= n jet production cross sections to the total inclusive Z/gamma* cross section in p anti-p collisions at s**(1/2) = 1.96-TeV

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Lett.B 658 (2008) 112-119, 2008.
Inspire Record 724239 DOI 10.17182/hepdata.42763

We present a study of events with Z bosons and jets produced at the Fermilab Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV. The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding to the integrated luminosity of 0.4 fb-1 collected using the D0 detector. Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross section have been measured for n = 1 to 4 jet events. Our measurements are found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.

4 data tables match query

Ratio of the cross sections.

Number of observed events per 5 GeV bin for the >=`1Jet sample. Data read from plots.

Number of observed events per 5 GeV bin for the >=2Jet sample. Data read from plots.

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Measurement of the $t \bar{t}$ production cross section in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.96-TeV in dilepton final states

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Lett.B 626 (2005) 55-64, 2005.
Inspire Record 683416 DOI 10.17182/hepdata.42759

We present a measurement of the top quark pair (ttbar) production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb-1 of data collected by the DO detector at the Fermilab Tevatron Collider. We select events in the dilepton final states ee, emu and mumu based on kinematical properties consistent with ttbar events. For a top quark mass of 175 GeV, we measure a top pair production cross section sigma(ttbar) = 8.6 +3.2-2.7 (stat) +/-1.1 (syst) +/-0.6 (lumi) pb, in good agreement with the standard model prediction.

1 data table match query

TTBAR production cross section.


Measurement of the $t \bar{t}$ production cross section in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.96-TeV using kinematic characteristics of lepton + jets events

The D0 collaboration Abazov, V.M. ; Abbott, B. ; Abolins, M. ; et al.
Phys.Rev.D 76 (2007) 092007, 2007.
Inspire Record 750966 DOI 10.17182/hepdata.42702

We present a measurement of the top quark pair production cross section in ppbar collisions at sqrt(s)=1.96 TeV utilizing 425 pb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider. We consider the final state of the top quark pair containing one high-pT electron or muon and at least four jets. We exploit specific kinematic features of ttbar events to extract the cross section. For a top quark mass of 175 GeV, we measure sigma_ttbar = 6.4 +1.3-1.2(stat} +/- 0.7(syst)+/- 0.4(lum) pb in good agreement with the standard model prediction.

1 data table match query

TOP TOPBAR production cross section.


Double boson production at D0

The D0 collaboration Yasuda, T. ;
567-573, 1996.
Inspire Record 423583 DOI 10.17182/hepdata.43003
1 data table match query

E + MU combined. Limits on CP-conserving anomalous W_W_GAMMA couplings DELTA(K) and LAMBDA (see paper). The cross section times branching ratio are presented.


Results from a search for a neutral scalar produced in association with a W boson in $p\bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
1996.
Inspire Record 424540 DOI 10.17182/hepdata.43005
1 data table match query

The cross section limits are set using two methods. The first (C=COUNT) is a simple counting experiment, and the second (C=SHAPE) use the shape of the dij et mass spectrum input to a likelihood fit.


Search for $W$ boson pair production in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8-TeV

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
1995.
Inspire Record 398747 DOI 10.17182/hepdata.43019
1 data table match query

Upper limit at the 95% C.L.


Inclusive $B$ quark and heavy quarkonium production at D$\emptyset$

The D0 collaboration Bazizi, Kamel A. ;
AIP Conf.Proc. 357 (2008) 105-119, 2008.
Inspire Record 398746 DOI 10.17182/hepdata.43020

We report the latest results on the measurement of inclusive b quark and heavy quarkonium production by the DO/ collaboration in pp̄ collisions at √s=1.8 TeV at the Fermilab Tevatron Collider. The results are from analyses of the 1992–93 data. This report includes measurements of inclusive b quark, J/ψ and Υ meson production cross sections. The b quark production cross section, measured in inclusive muon data, is consistent with next to leading order QCD predictions within theoretical and experimental errors. We study J/ψ and Υ meson production in dimuon events and perform an investigation of the J/ψ production mechanisms. Including the latest developments in charmonium phenomenology, the J/ψ production rates are now almost all accounted for in the transverse momentum range above 8 GeV/c. The observed Υ production rates, however, are higher than expected by a factor five.

2 data tables match query

No description provided.

No description provided.


Inclusive muon and $B$ quark production cross-sections in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8-TeV

The D0 collaboration Abachi, S. ; Abbott, B. ; Abolins, M. ; et al.
(1995), 1995.
Inspire Record 398709 DOI 10.17182/hepdata.43027

We have calculated the double and triple differential cross sections for electron ejection with energy of 14.6 eV in single ionization of H2 by 75 keV proton impact. A molecular version of the continuum distorted wave-eikonal initial state approach is applied, where the interaction between the projectile and the residual molecular ion is considered more properly than in previous applications of the method. For triple differential cross sections, the present results are in better agreement with the experimental data than those of other descriptions when large momentum transfer values are considered. For double differential cross sections the experimental data are reproduced quite well for both coherent and incoherent proton beams.

2 data tables match query

No description provided.

No description provided.


Observation of the top quark

The D0 collaboration Greenlee, Herbert ;
Frascati Phys.Ser. 2 (1995) 0695-712, 1995.
Inspire Record 395692 DOI 10.17182/hepdata.43028
1 data table match query

The cross section was obtained aunder the assumption that top quark has a mass of 200 GeV.


Measurement of the top quark pair production cross section in $p\bar{p}$ collisions using multijet final states

The D0 collaboration Abbott, B. ; Abolins, M. ; Abramov, V. ; et al.
Phys.Rev.D 60 (1999) 012001, 1999.
Inspire Record 475565 DOI 10.17182/hepdata.42156

We have studied tbar-t production using multijet final states in pbar-p collisions at a center-of-mass energy of 1.8 TeV, with an integrated luminosity of 110.3 pb(-1). Each of the top quarks with these final states decays exclusively to a bottom quark and a W boson, with the W bosons decaying into quark-antiquark pairs. The analysis has been optimized using neural networks to achieve the smallest expected fractional uncertainty on the tbar-t production cross section, and yields a cross section of 7.1 +/- 2.8(stat.) +/- 1.5(syst.) pb, assuming a top quark mass of 172.1 GeV/c^(2). Combining this result with previous D0 measurements, where one or both of the W bosons decay leptonically, gives a tbar t production cross section of 5.9 +/- 1.2(stat) +/- 1.1(syst) pb.

1 data table match query

The second value is the combination of the data reported here combined withthe previous result of D0 reported in PRL 79(1997)1203.


A Search for heavy point - like Dirac monopoles

The D0 collaboration Abbott, B. ; Abolins, M. ; Acharya, Bannanje Sripath ; et al.
Phys.Rev.Lett. 81 (1998) 524-529, 1998.
Inspire Record 468445 DOI 10.17182/hepdata.42158

We have searched for central production of a pair of photons with high transverse energies in $p\bar p$ collisions at $\sqrt{s} = 1.8$ TeV using $70 pb^{-1}$ of data collected with the D\O detector at the Fermilab Tevatron in 1994--1996. If they exist, virtual heavy pointlike Dirac monopoles could rescatter pairs of nearly real photons into this final state via a box diagram. We observe no excess of events above background, and set lower 95% C.L. limits of $610, 870, or 1580 GeV/c^2$ on the mass of a spin 0, 1/2, or 1 Dirac monopole.

1 data table match query

No description provided.


Search for first generation scalar leptoquark pairs in $p\bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV

The D0 collaboration Abbott, B. ; Abolins, M. ; Acharya, Bannanje Sripath ; et al.
Phys.Rev.Lett. 80 (1998) 2051-2056, 1998.
Inspire Record 450538 DOI 10.17182/hepdata.42159

We have searched for first generation scalar leptoquark (LQ) pairs in the enu+jets channel using ppbar collider data (integrated luminosity= 115 pb^-1) collected by the DZero experiment at the Fermilab Tevatron during 1992-96. The analysis yields no candidate events. We combine the results with those from the ee+jets and nunu+jets channels to obtain 95% confidence level (CL) upper limits on the LQ pair production cross section as a function of mass and of beta, the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95% CL lower limits on the LQ mass of 225, 204, and 79 GeV/c^2 for beta=1, 1/2, and 0, respectively.

1 data table match query

The cross section values are extracted with the assumption that BR(LQ --> EQUARK) = 1/2.


Direct measurement of the top quark mass at D0

The D0 collaboration Abbott, B. ; Abolins, M. ; Acharya, B.S. ; et al.
Phys.Rev.D 58 (1998) 052001, 1998.
Inspire Record 466578 DOI 10.17182/hepdata.42170

We determine the top quark mass m_t using t-tbar pairs produced in the D0 detector by \sqrt{s} = 1.8 TeV p-pbar collisions in a 125 pb^-1 exposure at the Fermilab Tevatron. We make a two constraint fit to m_t in t-tbar -> b W^+bbar W^- final states with one W boson decaying to q-qbar and the other to e-nu or mu-nu. Likelihood fits to the data yield m_t(l+jets) = 173.3 +- 5.6 (stat) +- 5.5 (syst) GeV/c^2. When this result is combined with an analysis of events in which both W bosons decay into leptons, we obtain m_t = 172.1 +- 5.2 (stat) +- 4.9 (syst) GeV/c^2. An alternate analysis, using three constraint fits to fixed top quark masses, gives m_t(l+jets) = 176.0 +- 7.9 (stat) +- 4.8 (syst) GeV/C^2, consistent with the above result. Studies of kinematic distributions of the top quark candidates are also presented.

1 data table match query

No description provided.


Search for scalar leptoquark pairs decaying to electrons and jets in $\bar{p}p$ collisions

The D0 collaboration Abbott, B. ; Abolins, M. ; Acharya, Bannanje Sripath ; et al.
Phys.Rev.Lett. 79 (1997) 4321-4326, 1997.
Inspire Record 446155 DOI 10.17182/hepdata.42172

We have searched for the pair production of first generation scalar leptoquarks in the eejj channel using the full data set (123 pb-1) collected with the D0 detector at the Fermilab Tevatron during 1992--1996. We observe no candidates with an expected background of approximately 0.4 events. Comparing the experimental 95% confidence level upper limit to theoretical calculations of the cross section with the assumption of a 100% branching fraction to eq, we set a lower limit on the mass of a first generation scalar leptoquark of 225 GeV/c^2. The results of this analysis rule out the interpretation of the excess of high Q^2 events at HERA as leptoquarks which decay exclusively to eq.

1 data table match query

No description provided.