Date

Subject_areas

Study of $D^{+} \to K^{-} \pi^+ e^+ \nu_e$

The BESIII collaboration Ablikim, Medina ; Achasov, Mikhail N ; Ai, Xiaocong ; et al.
Phys.Rev. D94 (2016) 032001, 2016.
Inspire Record 1411645 DOI 10.17182/hepdata.77048

We present an analysis of the decay D+→K-π+e+νe based on data collected by the BESIII experiment at the ψ(3770) resonance. Using a nearly background-free sample of 18262 events, we measure the branching fraction B(D+→K-π+e+νe)=(3.77±0.03±0.08)%. For 0.8<mKπ<1.0  GeV/c2, the partial branching fraction is B(D+→K-π+e+νe)[0.8,1.0]=(3.39±0.03±0.08)%. A partial wave analysis shows that the dominant K¯*(892)0 component is accompanied by an S-wave contribution accounting for (6.05±0.22±0.18)% of the total rate and that other components are negligible. The parameters of the K¯*(892)0 resonance and of the form factors based on the spectroscopic pole dominance predictions are also measured. We also present a measurement of the K¯*(892)0 helicity basis form factors in a model-independent way.

2 data tables

The $S$-wave phase $\delta_{S}$ measured in the 12 $m_{K\pi}$ bins with statistical and systematic uncertainties. The systematic uncertainties include: (I) background fraction, (II) background shape, (III) the $\bar K_{0}^{*}(1430)^{0}$ mass and width, (IV) additional resonances, (V) tracking efficiency correction, (VI) PID efficiency correction.

Average form-factor products in the $K^{*}$-dominated region.


Measurements of the atmospheric neutrino flux by Super-Kamiokande: energy spectra, geomagnetic effects, and solar modulation

The Super-Kamiokande collaboration Richard, E. ; Okumura, K. ; Abe, K. ; et al.
Phys.Rev. D94 (2016) 052001, 2016.
Inspire Record 1401192 DOI 10.17182/hepdata.76912

A comprehensive study of the atmospheric neutrino flux in the energy region from sub-GeV up to several TeV using the Super-Kamiokande (SK) water Cherenkov detector is presented in this paper. The energy and azimuthal spectra, and variation over time, of the atmospheric νe+ν¯e and νμ+ν¯μ fluxes are measured. The energy spectra are obtained using an iterative unfolding method by combining various event topologies with differing energy responses. The azimuthal spectra depending on energy and zenith angle, and their modulation by geomagnetic effects, are also studied. A predicted east-west asymmetry is observed in both the νe and νμ samples at 8.0σ and 6.0σ significance, respectively, and an indication that the asymmetry dipole angle changes depending on the zenith angle was seen at the 2.2σ level. The measured energy and azimuthal spectra are consistent with the current flux models within the estimated systematic uncertainties. A study of the long-term correlation between the atmospheric neutrino flux and the solar magnetic activity cycle is performed, and a weak preference for a correlation was seen at the 1.1σ level, using SK-I–SK-IV data spanning a 20-year period. For several particularly strong solar activity periods, corresponding to Forbush decrease events, no theoretical prediction is available but a deviation below the typical neutrino event rate is seen at the 2.4σ level. The seasonal modulation of the neutrino flux is also examined, but the change in flux at the SK site is predicted to be negligible, and, as expected, no evidence for a seasonal correlation is seen.

2 data tables

Electron neutrino flux measured by SK I-IV data. Error written in percentage including both statistical and systematic uncertainties.

Muon neutrino flux measured by SK I-IV data. Error written in percentage including both statistical and systematic uncertainties.


Measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon at $\langle E_{\nu} \rangle $ = 3.6 GeV

The MINERvA collaboration Wolcott, J. ; Aliaga, L. ; Altinok, O. ; et al.
Phys.Rev.Lett. 116 (2016) 081802, 2016.
Inspire Record 1393997 DOI 10.17182/hepdata.75538

The first direct measurement of electron neutrino quasielastic and quasielasticlike scattering on hydrocarbon in the few-GeV region of incident neutrino energy has been carried out using the MINERvA detector in the NuMI beam at Fermilab. The flux-integrated differential cross sections in the electron production angle, electron energy, and Q2 are presented. The ratio of the quasielastic, flux-integrated differential cross section in Q2 for νe with that of similarly selected νμ-induced events from the same exposure is used to probe assumptions that underpin conventional treatments of charged-current νe interactions used by long-baseline neutrino oscillation experiments. The data are found to be consistent with lepton universality and are well described by the predictions of the neutrino event generator GENIE.

9 data tables

The $\nu_{e}+\bar{\nu}_{e}$ flux as a function of neutrino energy from the beam simulation for the data used in this analysis. The $\bar{\nu}_{e}$ fraction is shown separately to emphasize the dominance of $\nu_{e}$ in the sum.

Flux-integrated differential $\nu_{e}$ CCQE-like cross section versus electron energy.

Covariance matrix for flux-integrated differential $\nu_{e}$ CCQE-like cross section versus electron energy.

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Measurements of top-quark pair to $Z$-boson cross-section ratios at $\sqrt s = 13, 8, 7$TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
No Journal Information, 2016.
Inspire Record 1502921 DOI 10.17182/hepdata.75536

Ratios of top-quark pair to $Z$-boson cross sections measured from proton--proton collisions at the LHC centre-of-mass energies of $\sqrt s=13$TeV, 8TeV, and 7TeV are presented by the ATLAS Collaboration. Single ratios, at a given $\sqrt s$ for the two processes and at different $\sqrt s$ for each process, as well as double ratios of the two processes at different $\sqrt s$, are evaluated. The ratios are constructed using previously published ATLAS measurements of the $t\overline{t}$ and $Z$-boson production cross sections, corrected to a common phase space where required, and a new analysis of $Z \rightarrow \ell^+ \ell^-$ where $\ell=e,\mu$ at $\sqrt s=13$TeV performed with data collected in 2015 with an integrated luminosity of $3.2$fb$^{-1}$. Correlations of systematic uncertainties are taken into account when evaluating the uncertainties in the ratios. The correlation model is also used to evaluate the combined cross section of the $Z\rightarrow e^+e^-$ and the $Z\rightarrow \mu^+ \mu^-$ channels for each $\sqrt s$ value. The results are compared to calculations performed at next-to-next-to-leading-order accuracy using recent sets of parton distribution functions. The data demonstrate significant power to constrain the gluon distribution function for the Bjorken-$x$ values near 0.1 and the light-quark sea for $x<0.02$.

11 data tables

Measured fiducial cross section times leptonic branching ratio for Z/gamma* production in the Z/gamma* -> e+e- final state at 13TeV.

Measured fiducial cross section times leptonic branching ratio for Z/gamma* production in the Z/gamma* -> mu+ mu- final state at 13TeV.

Breakdown of systematic uncertainties in percent for the measured fiducial cross section times leptonic branching ratio for Z/gamma* production in the Z/gamma* -> e+e- final state at 13TeV.

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Search for new resonances in events with one lepton and missing transverse momentum in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett. B762 (2016) 334-352, 2016.
Inspire Record 1469070 DOI 10.17182/hepdata.75363

A search for W′ bosons in events with one lepton (electron or muon) and missing transverse momentum is presented. The search uses 3.2 fb −1 of pp collision data collected at s=13 TeV by the ATLAS experiment at the LHC in 2015. The transverse mass distribution is examined and no significant excess of events above the level expected from Standard Model processes is observed. Upper limits on the W′ boson cross-section times branching ratio to leptons are set as a function of the W′ mass. Within the Sequential Standard Model W′ masses below 4.07 TeV are excluded at the 95% confidence level. This extends the limit set using LHC data at s=8 TeV by around 800 GeV.

4 data tables

Observed and predicted electron channel transverse mass (MT) distribution in the search region. The bin width is constant in log(MT).

Observed and predicted muon channel transverse mass (MT) distribution in the search region. The bin width is constant in log(MT).

W' Product of acceptance and efficiency for the electron and muon selections as a function of the SSM W' pole mass.

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Transverse-target-spin asymmetry in exclusive $\omega$-meson electroproduction

The HERMES collaboration Airapetian, A. ; Akopov, N. ; Akopov, Z. ; et al.
Eur.Phys.J. C75 (2015) 600, 2015.
Inspire Record 1391139 DOI 10.17182/hepdata.75465

Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi\omega$ transition form factor.

4 data tables

The amplitudes of the five sine and two cosine modulations as determined in the entire kinematic region. The results receive an additional 8.2% scale uncertainty corresponding to the target-polarization uncertainty.

The definition of intervals and the mean values of the kinematic variables.

Results on the kinematic dependences of the five asymmetry amplitudes $A_{UT}$ and two amplitudes $A_{UU}$. The first two columns correspond to the $-t'$ intervals $0.00 - 0.07 - 0.20$ GeV$^2$ and the last two columns to the $Q^{2}$ intervals $1.00 - 1.85 - 10.00$ GeV$^2$. The results receive an additional 8.2% scale uncertainty corresponding to the target-polarization uncertainty.

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Measurement of the $\eta_c (1S)$ production cross-section in proton-proton collisions via the decay $\eta_c (1S) \rightarrow p \bar{p}$

The LHCb collaboration Aaij, Roel ; Abellán Beteta, Carlos ; Adeva, Bernardo ; et al.
Eur.Phys.J. C75 (2015) 311, 2015.
Inspire Record 1316329 DOI 10.17182/hepdata.75251

The production of the $\eta _c (1S)$ state in proton-proton collisions is probed via its decay to the $p\overline{p}$ final state with the LHCb detector, in the rapidity range $2.0 < y < 4.5$ and in the meson transverse-momentum range $p_\mathrm{T} > 6.5 \mathrm{{\,GeV/}{ c}} $ . The cross-section for prompt production of $\eta _c (1S)$ mesons relative to the prompt ${{ J}}/{\psi } $ cross-section is measured, for the first time, to be $\sigma _{\eta _c (1S)}/\sigma _{{{{ J}}/{\psi }}} = 1.74\, \pm \,0.29\, \pm \, 0.28\, \pm \,0.18 _{{\mathcal{B}}}$ at a centre-of-mass energy ${\sqrt{s}} = 7 {~\mathrm{TeV}}$ using data corresponding to an integrated luminosity of 0.7 fb$^{-1}$ , and $\sigma _{\eta _c (1S)}/\sigma _{{{{ J}}/{\psi }}} = 1.60 \pm 0.29 \pm 0.25 \pm 0.17 _{{\mathcal{B}}}$ at ${\sqrt{s}} = 8 {~\mathrm{TeV}}$ using 2.0 fb$^{-1}$ . The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the $\eta _c (1S)$ and ${{ J}}/{\psi } $ decays to the $p\overline{p}$ final state. In addition, the inclusive branching fraction of ${b} $ -hadron decays into $\eta _c (1S)$ mesons is measured, for the first time, to be ${\mathcal{B}}( b {\rightarrow } \eta _c X ) = (4.88\, \pm \,0.64\, \pm \,0.29\, \pm \, 0.67 _{{\mathcal{B}}}) \times 10^{-3}$ , where the third uncertainty includes also the uncertainty on the ${{ J}}/{\psi } $ inclusive branching fraction from ${b} $ -hadron decays. The difference between the ${{ J}}/{\psi } $ and $\eta _c (1S)$ meson masses is determined to be $114.7 \pm 1.5 \pm 0.1 {\mathrm {\,MeV\!/}c^2} $ .

4 data tables

Differential cross-section for $\eta_c(1S)$ prompt production for $p_T > 6.5$ [GeV/$c$] and $2.0 < y < 4.5$. The reported uncertainties are total errors.

Differential cross-section for $\eta_c(1S)$ prompt production for $p_T > 6.5$ [GeV/$c$] and $2.0 < y < 4.5$. The reported uncertainties are total errors.

Differential cross-section for $\eta_c(1S)$ from inclusive charmonium production in b-hadrons decays for $p_T > 6.5$ [GeV/$c$] and $2.0 < y < 4.5$. The reported uncertainties are total errors.

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Study of Dynamics of $D^0 \to K^- e^+ \nu_{e}$ and $D^0\to\pi^- e^+ \nu_{e}$ Decays

The BESIII collaboration Ablikim, M. ; Achasov, M.N. ; Ai, X.C. ; et al.
Phys.Rev. D92 (2015) 072012, 2015.
Inspire Record 1391138 DOI 10.17182/hepdata.74726

In an analysis of a 2.92~fb$^{-1}$ data sample taken at 3.773~GeV with the BESIII detector operated at the BEPCII collider, we measure the absolute decay branching fractions to be $\mathcal B(D^0 \to K^-e^+\nu_e)=(3.505\pm 0.014 \pm 0.033)\%$ and $\mathcal B(D^0 \to \pi^-e^+\nu_e)=(0.295\pm 0.004\pm 0.003)\%$. From a study of the differential decay rates we obtain the products of hadronic form factor and the magnitude of the CKM matrix element $f_{+}^K(0)|V_{cs}|=0.7172\pm0.0025\pm 0.0035$ and $f_{+}^{\pi}(0)|V_{cd}|=0.1435\pm0.0018\pm 0.0009$. Combining these products with the values of $|V_{cs(d)}|$ from the SM constraint fit, we extract the hadronic form factors $f^K_+(0) = 0.7368\pm0.0026\pm 0.0036$ and $f^\pi_+(0) = 0.6372\pm0.0080\pm 0.0044$, and their ratio $f_+^{\pi}(0)/f_+^{K}(0)=0.8649\pm 0.0112\pm 0.0073$. These form factors and their ratio are used to test unquenched Lattice QCD calculations of the form factors and a light cone sum rule (LCSR) calculation of their ratio. The measured value of $f_+^{K(\pi)}(0) |V_{cs(d)}|$ and the lattice QCD value for $f^{K(\pi)}_+(0)$ are used to extract values of the CKM matrix elements of $|V_{cs}|=0.9601 \pm 0.0033 \pm 0.0047 \pm 0.0239$ and $|V_{cd}|=0.2155 \pm 0.0027 \pm 0.0014 \pm 0.0094$, where the third errors are due to the uncertainties in lattice QCD calculations of the form factors. Using the LCSR value for $f_+^\pi(0)/f_+^K(0)$, we determine the ratio $|V_{cd}|/|V_{cs}|=0.238\pm 0.004\pm 0.002\pm 0.011$, where the third error is from the uncertainty in the LCSR normalization. In addition, we measure form factor parameters for three different theoretical models that describe the weak hadronic charged currents for these two semileptonic decays. All of these measurements are the most precise to date.

2 data tables

Summary of the range of each $q^2$ bin, the number of the observed events $N_{\rm observed}$, the number of produced events $N_{\rm produced}$, and the partial decay rate $\Delta\Gamma$ in each $q^2$ bin for $D^0\to K^-e^+\nu_e$ decays.

Summary of the range of each $q^2$ bin, the number of the observed events $N_{\rm observed}$, the number of produced events $N_{\rm produced}$, and the partial decay rate $\Delta\Gamma$ in each $q^2$ bin for $D^0\to \pi^-e^+\nu_e$ decays.


Evidence for exclusive $\gamma\gamma \to W^+ W^-$ production and constraints on anomalous quartic gauge couplings in $pp$ collisions at $ \sqrt{s}=7 $ and 8 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
JHEP 1608 (2016) 119, 2016.
Inspire Record 1448100 DOI 10.17182/hepdata.74707

A search for exclusive or quasi-exclusive γγ → W$^{+}$ W$^{−}$ production, via pp → p$^{(*)}$ W$^{+}$ W$^{−}$ p$^{(*)}$ → p$^{(*)}$ μ$^{±}$e$^{∓}$ p$^{(*)}$ at $ \sqrt{s}=8 $ TeV, is reported using data corresponding to an integrated luminosity of 19.7 fb$^{−1}$. Events are selected by requiring the presence of an electron-muon pair with large transverse momentum p$_{T}$(μ$^{±}$e$^{∓}$) > 30 GeV, and no associated charged particles detected from the same vertex. The 8 TeV results are combined with the previous 7 TeV results (obtained for 5.05 fb$^{−1}$ of data). In the signal region, 13 (2) events are observed over an expected background of 3.9 ± 0.6 (0.84 ± 0.15) events for 8 (7) TeV, resulting in a combined excess of 3.4σ over the background-only hypothesis. The observed yields and kinematic distributions are compatible with the standard model prediction for exclusive and quasi-exclusive γγ → W$^{+}$ W$^{−}$ production. Upper limits on the anomalous quartic gauge coupling operators a$_{0,C}^{W}$ (dimension-6) and f$_{M0,1,2,3}$ (dimension-8), the most stringent to date, are derived from the measured dilepton transverse momentum spectrum.

1 data table

8 TeV cross section multiplied by branching fraction to opposite-sign mue final states, corrected for all experimental efficiencies and extrapolated to the full phase space.


Measurement of the t-tbar production cross section in the e-mu channel in proton-proton collisions at sqrt(s) = 7 and 8 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
JHEP 1608 (2016) 029, 2016.
Inspire Record 1426692 DOI 10.17182/hepdata.74208

The inclusive cross section for top quark pair production is measured in proton-proton collisions at $ \sqrt{s}=7 $ and 8 TeV, corresponding to 5.0 and 19.7 fb$^{−1}$, respectively, with the CMS experiment at the LHC. The cross sections are measured in the electron-muon channel using a binned likelihood fit to multi-differential final state distributions related to identified b quark jets and other jets in the event. The measured cross section values are 173.6 ± 2.1(stat)$_{− 4.0}^{+ 4.5}$ (syst) ± 3.8(lumi)pb at $ \sqrt{s}=7 $ TeV, and 244.9 ± 1.4(stat)$_{− 5.5}^{+ 6.3}$ (syst) ± 6.4(lumi)pb at $ \sqrt{s}=8 $ TeV, in good agreement with QCD calculations at next-to-next-to-leading-order accuracy. The ratio of the cross sections measured at 7 and 8 TeV is determined, as well as cross sections in the fiducial regions defined by the acceptance requirements on the two charged leptons in the final state. The cross section results are used to determine the top quark pole mass via the dependence of the theoretically predicted cross section on the mass, giving a best result of 173. 8$_{− 1.8}^{+ 1.7}$ GeV. The data at $ \sqrt{s}=8 $ TeV are also used to set limits, for two neutralino mass values, on the pair production of supersymmetric partners of the top quark with masses close to the top quark mass.

3 data tables

Measurement of the visible $t\bar{t}$ production cross-section in $pp$ collisions at $\sqrt{s} = 7$ and $8$ TeV. The visible cross section is defined for events containing an oppositely charged $\rm{e}\mu$ pair from the decay chain ${\rm t} \rightarrow {\rm W b} \rightarrow {\ell} \nu {\rm b}$ (including ${\rm W} \rightarrow \tau \nu \rightarrow {\ell} \nu \nu \nu$) and with both leptons satisfying $p_T > 20\, \rm{GeV}$ and $|{\eta}| < 2.4$.

Measurement of the inclusive $t\bar{t}$ production cross-section in $pp$ collisions at $\sqrt{s} = 7$ and $8$ TeV.

Top quark pole mass at NNLO+NNLL extracted by comparing the measured $t\bar{t}$ production cross sections at 7 and 8 TeV with predictions employing different PDF sets. The uncertainties of the CT14 PDF set are scaled to 68% confidence level.


Production of exclusive dijets in diffractive deep inelastic scattering at HERA

The ZEUS collaboration Abramowicz, H. ; Abt, I. ; Adamczyk, L. ; et al.
Eur.Phys.J. C76 (2016) 16, 2016.
Inspire Record 1372086 DOI 10.17182/hepdata.73738

Production of exclusive dijets in diffractive deep inelastic $e^\pm p$ scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb$^{-1}$. The measurement was performed for $\gamma^*-p$ centre-of-mass energies in the range $90 < W < 250$ GeV and for photon virtualities $Q^2 > 25$ GeV$^2$. Energy and transverse-energy flows around the jet axis are presented. The cross section is presented as a function of $\beta$ and $\phi$, where $\beta=x/x_{\rm I\!P}$, $x$ is the Bjorken variable and $x_{\rm I\!P}$ is the proton fractional longitudinal momentum loss. The angle $\phi$ is defined by the $\gamma^*-$dijet plane and the $\gamma^*-e^\pm$ plane in the rest frame of the diffractive final state. The $\phi$ cross section is measured in bins of $\beta$. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.

3 data tables

Differential cross-section $d\sigma/d\beta$ in the kinematic range: $Q^2 > 25 GeV^2$, $90 < W < 250 GeV^2$, $x_{\rm I\!P} < 0.01$, $M_X > 5 GeV$ and $p_{T,jet} > 2 GeV$. The contribution from proton dissociation was subtracted. The uncertainty of the subtraction determines the uncertainty of the normalisation also given in the table.

Differential cross-section $d\sigma/d\phi$ in the kinematic range: $Q^2 > 25 GeV^2$, $90 < W < 250 GeV$, $x_{\rm I\!P} < 0.01$, $M_X > 5 GeV$ and $p_{T,jet} > 2 GeV$. The contribution from proton dissociation was subtracted. The uncertainty of the subtraction determines the uncertainty of the normalisation given in the table.

Results of the fit to the cross-section $d\sigma/d\phi$ in bins of $\beta$. The fitted function is proportional to $(1+A \rm{cos}2\phi)$. The uncertainty includes both statistical and systematical contributions (see text of paper).


Search for a Higgs boson decaying into $\gamma^* \gamma \to \ell \ell \gamma$ with low dilepton mass in pp collisions at $\sqrt s = $ 8 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett. B753 (2016) 341-362, 2016.
Inspire Record 1382587 DOI 10.17182/hepdata.73712

A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair ( ℓℓγ ). The analysis is performed using proton–proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb −1 . The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120<mℓℓγ<150 GeV , and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H→γ⁎γ→ℓℓγ , where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with mH=125 GeV , a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 ( 5.9−1.8+2.8 ) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H→(J/ψ)γ for the 125 GeV Higgs boson is set at 1.5×10−3 .

4 data tables

The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.

The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.

The 95% CL exclusion limit, as a function of the mass hypothesis, $m_H$ , on $\sigma/\sigma_{SM}$, the cross section times the branching fraction of a Higgs boson decaying into a photon and a lepton pair with $m_{\ell\ell}$ < 20 GeV, divided by the SM value.

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Search for the isospin violating decay Y(4260)→J/ψηπ$^0$

The BESIII collaboration Ablikim, M. ; Achasov, M.N. ; Ai, X.C. ; et al.
Phys.Rev. D92 (2015) 012008, 2015.
Inspire Record 1366025 DOI 10.17182/hepdata.73692

Using data samples collected at center-of-mass energies of s=4.009, 4.226, 4.257, 4.358, 4.416, and 4.599 GeV with the BESIII detector operating at the BEPCII storage ring, we search for the isospin violating decay Y(4260)→J/ψηπ0. No signal is observed, and upper limits on the cross section σ(e+e-→J/ψηπ0) at the 90% confidence level are determined to be 3.6, 1.7, 2.4, 1.4, 0.9, and 1.9 pb, respectively.

1 data table

Results on $e^{+}e^{-}\rightarrow J/\psi\eta\pi^{0}$. Listed in the table are the integrated luminosity $\cal{L}$, radiative correction factor (1+$\delta^{r}$) taken from QED calculation assuming the $Y(4260)$ cross section follows a Breit$-$Wigner line shape, vacuum polarization factor (1+$\delta^{v}$), average efficiency ($\epsilon^{ee}{\cal B}^{ee}$ + $\epsilon^{\mu\mu}{\cal B}^{\mu\mu}$), number of observed events $N^\text{obs}$, number of estimated background events $N^\text{bkg}$, the efficiency corrected upper limits on the number of signal events $N^\text{up}$, and upper limits on the Born cross section $\sigma^\text{Born}_\text{UL}$ (at the 90 $\%$ C.L.) at each energy point.


Measurement of parity-violating spin asymmetries in W$^{\pm}$ production at midrapidity in longitudinally polarized $p$$+$$p$ collisions

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev. D93 (2016) 051103, 2016.
Inspire Record 1365091 DOI 10.17182/hepdata.73691

We present midrapidity measurements from the PHENIX experiment of large parity-violating single-spin asymmetries of high transverse momentum electrons and positrons from W±/Z decays, produced in longitudinally polarized p+p collisions at center of mass energies of s=500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parity-violating nature of the W-boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240  pb-1, which exceeds previous PHENIX published results by a factor of more than 27. These high Q2 data probe the parton structure of the proton at W mass scale and provide an important addition to our understanding of the antiquark parton helicity distribution functions at an intermediate Bjorken x value of roughly MW/s=0.16.

1 data table

Longitudinal single-spin asymmetries, $A_L$, for the 2011 and 2012 data sets (combined) spanning the entire $\eta$ range of PHENIX ($\left|\eta\right|<0.35$), for the 2013 data set separated into two $\eta$ bins, and for the combined 2011-2013 data sets.


Observation of the Dalitz Decay $\eta' \to \gamma e^+e^-$

The BESIII collaboration Ablikim, M. ; Achasov, M.N. ; Ai, X.C. ; et al.
Phys.Rev. D92 (2015) 012001, 2015.
Inspire Record 1364494 DOI 10.17182/hepdata.73672

We report the first observation of the Dalitz decay $\eta' \to \gamma e^+e^-$, based on a data sample of 1.31 billion $J/\psi$ events collected with the BESIII detector. The $\eta'$ mesons are produced via the $J/\psi \to \gamma \eta'$ decay process. The ratio $\Gamma(\eta' \to \gamma e^+ e^-)/\Gamma(\eta'\to\gamma\gamma)$ is measured to be $(2.13\pm0.09(\text{stat.})\pm0.07(\text{sys.}))\times10^{-2}$. This corresponds to a branching fraction ${\cal B}(\eta' \to \gamma e^+e^-)= (4.69 \pm0.20(\text{stat.})\pm0.23(\text{sys.}))\times10^{-4}$. The transition form factor is extracted and different expressions are compared to the measured dependence on the $e^+e^-$ invariant mass. The results are consistent with the prediction of the Vector Meson Dominance model.

2 data tables

Fitted ($n^{\text{obs}}_i$) and efficiency-corrected ($n^{\text{corr}}_i$) signal yields for the eight $M(e^+e^-)$ bins, and ratios ($r_i$). The uncertainties are statistical only.

Values of $|F|^2$ in each $M(e^+e^-)$ bin.


Measurement of $W^{\pm}$ and $Z$-boson production cross sections in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Phys.Lett. B759 (2016) 601-621, 2016.
Inspire Record 1436497 DOI 10.17182/hepdata.73611

Measurements of the $W^{\pm} \rightarrow \ell^{\pm} \nu$ and $Z \rightarrow \ell^+ \ell^-$ production cross sections (where $\ell^{\pm}=e^{\pm},\mu^{\pm}$) in proton-proton collisions at $\sqrt{s}=13$ TeV are presented using data recorded by the ATLAS experiment at the Large Hadron Collider, corresponding to a total integrated luminosity of 81 pb$^{-1}$ The total inclusive $W^{\pm}$-boson production cross sections times the single-lepton-flavour branching ratios are $\sigma_{W^+}^{tot}= 11.83 \pm 0.02 (stat) \pm 0.32 (sys) \pm 0.25 (lumi)$ nb and $\sigma_{W^-}^{tot} = 8.79 \pm 0.02 (stat) \pm 0.24 (sys) \pm 0.18 (lumi)$ nb for $W^+$ and $W^-$, respectively. The total inclusive $Z$-boson production cross section times leptonic branching ratio, within the invariant mass window $66 < m_{\ell\ell} < 116$ GeV, is $\sigma_{Z}^{tot} = 1.981 \pm 0.007 (stat) \pm 0.038 (sys) \pm 0.042 (lumi)$ nb. The $W^+$, $W^-$, and $Z$-boson production cross sections and cross-section ratios within a fiducial region defined by the detector acceptance are also measured. The cross-section ratios benefit from significant cancellation of experimental uncertainties, resulting in $\sigma_{W^+}^{fid}/\sigma_{W^-}^{fid} = 1.295 \pm 0.003 (stat) \pm 0.010 (sys)$ and $\sigma_{W^{\pm}}^{fid}/\sigma_{Z}^{fid} = 10.31 \pm 0.04 (stat) \pm 0.20 (sys)$. Theoretical predictions, based on calculations accurate to next-to-next-to-leading order for quantum chromodynamics and to next-to-leading order for electroweak processes and which employ different parton distribution function sets, are compared to these measurements.

24 data tables

Measured fiducial cross section times leptonic branching ratio for W+ production in the W+ -> e+ nu final state.

Measured fiducial cross section times leptonic branching ratio for W- production in the W- -> e- nubar final state.

Measured fiducial cross section times leptonic branching ratio for Z/gamma* production in the Z/gamma* -> e+e- final state.

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Measurements of Dielectron Production in Au$+$Au Collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV from the STAR Experiment

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev. C92 (2015) 024912, 2015.
Inspire Record 1357992 DOI 10.17182/hepdata.73504

We report on measurements of dielectron (e+e−) production in Au+Au collisions at a center-of-mass energy of 200 GeV per nucleon-nucleon pair using the STAR detector at BNL Relativistic Heavy Ion Collider. Systematic measurements of the dielectron yield as a function of transverse momentum (pT) and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region (Mee<1GeV/c2). This enhancement cannot be reproduced by the ρ-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of 0.30–0.76GeV/c2, integrated over the full pT acceptance, the enhancement factor is 1.76±0.06(stat.)±0.26(sys.)±0.29(cocktail). The enhancement factor exhibits weak centrality and pT dependence in STAR's accessible kinematic regions, while the excess yield in this invariant-mass region as a function of the number of participating nucleons follows a power-law shape with a power of 1.44±0.10. Models that assume an in-medium broadening of the ρ-meson spectral function consistently describe the observed excess in these measurements. Additionally, we report on measurements of ω- and ϕ-meson production through their e+e− decay channel. These measurements show good agreement with Tsallis blast-wave model predictions, as well as, in the case of the ϕ meson, results through its K+K− decay channel. In the intermediate invariant-mass region (1.1<Mee<3GeV/c2), we investigate the spectral shapes from different collision centralities. Physics implications for possible in-medium modification of charmed hadron production and other physics sources are discussed.

50 data tables

Estimated electron purity vs. momentum in 200 GeV Au + Au collisions.

Acceptance correction factor for unlike-sign and like-sign pair difference from 200 GeV Au+Au minimum-bias collisions.

Ratio of the same-event like-sign to the mixed event unlike-sign distributions.

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Measurement of the $e^{+}e^{-} \to \eta J/\psi$ cross section and search for $e^{+}e^{-} \to \pi^{0} J/\psi$ at center-of-mass energies between 3.810 and 4.600 GeV

The BESIII collaboration Ablikim, M. ; Achasov, M.N. ; Ai, X.C. ; et al.
Phys.Rev. D91 (2015) 112005, 2015.
Inspire Record 1355215 DOI 10.17182/hepdata.73336

Using data samples collected with the BESIII detector operating at the BEPCII collider at 17 center-of-mass energies from 3.810 to 4.600 GeV, we perform a study of e+e-→ηJ/ψ and π0J/ψ. The Born cross sections of these two processes are measured at each center-of-mass energy. The measured energy-dependent Born cross section for e+e-→ηJ/ψ shows an enhancement around 4.2 GeV. The measurement is compatible with an earlier measurement by Belle.

3 data tables

Results on $e^{+}e^{-}\to\eta J/\psi$ in data samples in which a signal is observed with a statistical significance larger than $5\sigma$. The table shows the CM energy $\sqrt{s}$, integrated luminosity $\mathcal{L}_\mathrm{int}$, number of observed $\eta$ events $N^\mathrm{obs}_{\eta}(\mu^{+}\mu^{-})$/$N^\mathrm{obs}_{\eta}(e^{+}e^{-})$ from the fit, efficiency $\epsilon_{\mu}/\epsilon_{e}$, radiative correction factor $(1+\delta^{r})$, vacuum polarization factor $(1+\delta^{v})$, Born cross section $\sigma^{B}(\mu^{+}\mu^{-})$/$\sigma^{B}(e^{+}e^{-})$ and combined Born cross section $\sigma^{B}_\mathrm{Com}$. The first uncertainties are statistical and the second systematic.

Upper limits of $e^{+}e^{-} \to \eta J/\psi$ using the $\mu^{+}\mu^{-}$ mode. The table shows the CM energy $\sqrt{s}$, integrated luminosity $\mathcal{L}_\mathrm{int}$, number of observed $\eta$ events $N^\mathrm{sg}_{\eta}$, number of background from $\eta$ sideband $N^\mathrm{sb}_{\eta}$, and from $J/\psi$ sideband $N^\mathrm{sb}_{J/\psi}$, efficiency $\epsilon$, upper limit of signal number with the consideration of selection efficiency $N^\mathrm{up}_{\eta}/\epsilon$ (at the $90\%$ C.L.), radiative correction factor $(1+\delta^{r})$, vacuum polarization factor $(1+\delta^{v})$, Born cross section $\sigma^{B}$ and upper limit on the Born cross sections $\sigma^{B}_\mathrm{up}$ (at the $90\%$ C.L.). The first uncertainties are statistical and the second systematic.

Upper limits of $e^{+}e^{-} \to \pi^{0} J/\psi$. The table shows the number of observed events in the $\pi^{0}$ signal region $N^\mathrm{sg}$, number of events in $\pi^{0}$ sideband $N^\mathrm{sb}_{\pi^{0}}$, and in $J/\psi$ sideband $N^\mathrm{sb}_{J/\psi}$, efficiency $\epsilon$, the upper limit of signal events with the consideration of the selection efficiency $N^\mathrm{up}(\mu^{+}\mu^{-})/\epsilon$ (at the $90\%$ C.L.) and the upper limit of Born cross sections $\sigma^{B}_\mathrm{up}$ (at the $90\%$ C.L.).


Combination of differential D$^{∗\pm}$ cross-section measurements in deep-inelastic ep scattering at HERA

The H1 ZEUS collaborations Abramowicz, H. ; Abt, I. ; Adamczyk, L. ; et al.
JHEP 1509 (2015) 149, 2015.
Inspire Record 1353667 DOI 10.17182/hepdata.73328

H1 and ZEUS have published single-differential cross sections for inclusive D$^{∗±}$-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q$^{2}$ > 5 GeV$^{2}$, electron inelasticity 0.02 < y < 0.7 and the D$^{∗±}$ meson’s transverse momentum p$_{T}$(D$^{∗}$) > 1.5 GeV and pseudorapidity |η(D$^{∗}$)| < 1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d$^{2}$ σ/dQ$^{2}$dy are combined with earlier D$^{∗±}$ data, extending the kinematic range down to Q$^{2}$ > 1.5 GeV$^{2}$. Perturbative next-to-leading-order QCD predictions are compared to the results.

6 data tables

The combined differential $D^{*\pm}$-production cross section as a function of $p_T(D^{*})$, with its uncorrelated and correlated uncertainties.

The combined differential $D^{*\pm}$-production cross section as a function of $\eta(D^{*})$, with its uncorrelated and correlated uncertainties.

The combined differential $D^{*\pm}$-production cross section as a function of $z(D^{*})$, with its uncorrelated and correlated uncertainties.

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Measurement of forward $\rm Z\rightarrow e^+e^-$ production at $\sqrt{s}=8$ TeV

The LHCb collaboration Aaij, Roel ; Adeva, Bernardo ; Adinolfi, Marco ; et al.
JHEP 1505 (2015) 109, 2015.
Inspire Record 1347133 DOI 10.17182/hepdata.73305

A measurement of the cross-section for Z-boson production in the forward region of pp collisions at 8 TeV centre-of-mass energy is presented. The measurement is based on a sample of Z → e$^{+}$e$^{−}$ decays reconstructed using the LHCb detector, corresponding to an integrated luminosity of 2.0 fb$^{−1}$. The acceptance is defined by the requirements 2.0 < η < 4.5 and p$_{T}$ > 20 GeV for the pseudorapidities and transverse momenta of the leptons. Their invariant mass is required to lie in the range 60-120 GeV. The cross-section is determined to be $ \sigma \left(\mathrm{pp}\to \mathrm{Z}\to {\mathrm{e}}^{+}{\mathrm{e}}^{-}\right)=93.81\pm 0.41\left(\mathrm{stat}\right)\pm 1.48\left(\mathrm{syst}\right)\pm 1.14\left(\mathrm{lumi}\right)\mathrm{p}\mathrm{b}, $ where the first uncertainty is statistical and the second reflects all systematic effects apart from that arising from the luminosity, which is given as the third uncertainty. Differential cross-sections are presented as functions of the Z-boson rapidity and of the angular variable ϕ$^{∗}$, which is related to the Z-boson transverse momentum.

3 data tables

Integrated cross-section for Z$\to$ e$^+$e$^-$ within the LHCb acceptance.

Differential cross-section for Z$\to$ e$^+$e$^-$ as a function of Z-boson rapidity. The first error is statistical, the second the uncorrelated experimental systematic, the third the correlated experimental systematic and the last error is the uncertainty in luminosity. The cross-sections are at the Born level, i.e. before FSR. The rightmost column gives values of the additional factor, $f_{\rm FSR}$, by which the results should be multiplied in order to give the cross-sections after FSR.

Differential cross-section for Z$\to$ e$^+$e$^-$ as a function of $\phi^*$. The first error is statistical, the second the uncorrelated experimental systematic, the third the correlated experimental systematic and the last error is the uncertainty in luminosity. The cross-sections are at the Born level, i.e. before FSR. The rightmost column gives values of the additional factor, $f_{\rm FSR}$, by which the results should be multiplied in order to give the cross-sections after FSR.


Diffractive Dijet Production with a Leading Proton in $ep$ Collisions at HERA

The H1 collaboration Andreev, V. ; Baghdasaryan, A. ; Begzsuren, K. ; et al.
JHEP 1505 (2015) 056, 2015.
Inspire Record 1343110 DOI 10.17182/hepdata.73234

The cross section of the diffractive process e^+p -> e^+Xp is measured at a centre-of-mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities Q^2 <2 GeV^2 and in deep-inelastic scattering with 4 GeV^2<Q^2<80 GeV^2. The results are compared to next-to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering.

23 data tables

Integrated $e^{+}p$ diffractive dijet cross sections in $\gamma p$. The hadronisation correction factor ($1+\delta_{\text{hadr}}$) applied to the NLO calculation is also listed. The overall normalisation uncertainty of $6\%$ is not included in the table.

Integrated $e^{+}p$ diffractive dijet cross sections in DIS. The hadronisation correction factor ($1+\delta_{\text{hadr}}$) applied to the NLO calculation and the radiative correction ($1+\delta_{\text{rad}}$) are also listed. The overall normalisation uncertainty of $6\%$ is not included in the table.

Ratio of integrated $e^{+}p$ diffractive dijet cross sections for $Q^2<2\,\text{GeV}^2$ (photoproduction) to $Q^2>4\,\text{GeV}^2$ (DIS).

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Measurement of the transverse single-spin asymmetry in $p^\uparrow+p \to W^{\pm}/Z^0$ at RHIC

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 116 (2016) 132301, 2016.
Inspire Record 1405433 DOI 10.17182/hepdata.73263

We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at s=500  GeV by the STAR experiment at RHIC. The measured observable is sensitive to the Sivers function, one of the transverse-momentum-dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD.

6 data tables

$P_{T}$ Recoil distribution of events simulated with PYTHIA 6.4 and reconstructed before and after the boson's PT correction has been applied.

Estimated background contributions for the $W^+ -> ev$ data yields.

Estimated background contributions for the $W^- -> ev$ data yields.

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Forward–backward asymmetry of Drell–Yan lepton pairs in pp collisions at $\sqrt{s} = 8$ $\,\mathrm{TeV}$

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Eur.Phys.J. C76 (2016) 325, 2016.
Inspire Record 1415949 DOI 10.17182/hepdata.73121

A measurement of the forward–backward asymmetry ${A}_{\mathrm{FB}}$ of oppositely charged lepton pairs ( $\mu \mu $ and $\mathrm{e}\mathrm{e}$ ) produced via $\mathrm{Z}/\gamma ^*$ boson exchange in pp collisions at $\sqrt{s} = 8$ $\,\mathrm{TeV}$ is presented. The data sample corresponds to an integrated luminosity of 19.7 $\,\mathrm{fb}^{-1}$ collected with the CMS detector at the LHC. The measurement of ${A}_{\mathrm{FB}}$ is performed for dilepton masses between 40 $\,\text {GeV}$ and 2 $\,\mathrm{TeV}$ and for dilepton rapidity up to 5. The ${A}_{\mathrm{FB}}$ measurements as a function of dilepton mass and rapidity are compared with the standard model predictions.

40 data tables

Unfolded combined measurements of AFB in each M-|y| bin (mu+mu- and e+e- combined).

Unfolded measurement of AFB for the forward rapidity region (e+e-).

Unfolded measurements of AFB in each M-|y| bin (mu+mu-).

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