Events with Isolated Leptons and Missing Transverse Momentum and Measurement of W Production at HERA

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Eur.Phys.J.C 64 (2009) 251-271, 2009.
Inspire Record 810292 DOI 10.17182/hepdata.53047

Events with high energy isolated electrons, muons or tau leptons and missing transverse momentum are studied using the full e^\pm p data sample collected by the H1 experiment at HERA, corresponding to an integrated luminosity of 474 pb^{-1}. Within the Standard Model, events with isolated leptons and missing transverse momentum mainly originate from the production of single W bosons. The total single W boson production cross section is measured as 1.14 \pm 0.25 (stat.) \pm 0.14 (sys.) pb, in agreement with the Standard Model expectation. The data are also used to establish limits on the WW\gamma gauge couplings and for a measurement of the W boson polarisation.

2 data tables

Total single W boson production cross section.

Differential single W boson production cross section.


Measurement of the Inclusive ep Scattering Cross Section at Low $Q^2$ and x at HERA

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Eur.Phys.J.C 63 (2009) 625-678, 2009.
Inspire Record 817368 DOI 10.17182/hepdata.52425

A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2 GeV^2 < Q^2 < 12 GeV^2, and low Bjorken x, 5x10^-6 < x < 0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously published by H1 leads to a cross section measurement of a few percent accuracy. A kinematic reconstruction method exploiting radiative ep events extends the measurement to lower Q^2 and larger x. The data are compared with theoretical models which apply to the transition region from photoproduction to deep inelastic scattering.

39 data tables

Reduced cross section as measured in the SVX data sample for Q**2 = 0.20 GeV**2. Additional 3 PCT luminosity uncertainty not included in the total error.

Reduced cross section as measured in the SVX data sample for Q**2 = 0.25 GeV**2. Additional 3 PCT luminosity uncertainty not included in the total error.

Reduced cross section as measured in the SVX data sample for Q**2 = 0.35 GeV**2. Additional 3 PCT luminosity uncertainty not included in the total error.

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Measurement of Diffractive Scattering of Photons with Large Momentum Transfer at HERA

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Phys.Lett.B 672 (2009) 219-226, 2009.
Inspire Record 799783 DOI 10.17182/hepdata.45289

The first measurement of diffractive scattering of quasi-real photons with large momentum transfer gamma p -> gamma Y, where Y is the proton dissociative system, is made using the H1 detector at HERA. The measurement is performed for initial photon virtualities Q^2 &lt; 0.01 GeV^2. Cross sections are measured as a function of W, the incident photon-proton entre of mass energy, and t, the square of the four-momentum transferred at the proton vertex, in the range 175 &lt; W &lt; 247 GeV and 4&lt;|t|&lt;36 GeV^2. The W dependence is well described by a model based on perturbative QCD using a leading logarithmic approximation of the BFKL evolution. The measured |t| dependence is harder than that predicted by the model and those observed in exclusive vector meson production.

4 data tables

Cross section for the process E+ P --> E+ GAMMA DD as a function of W.

Cross section for the process GAMMA P --> GAMMA DD as a function of W.

Cross section for the process E+ P --> E+ GAMMA DD as a function of T.

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Measurement of the e+ e- ---> b anti-b cross section between s**(1/2) = 10.54-GeV and 11.20-GeV

The BaBar collaboration Aubert, Bernard ; Bona, M. ; Karyotakis, Y. ; et al.
Phys.Rev.Lett. 102 (2009) 012001, 2009.
Inspire Record 797507 DOI 10.17182/hepdata.18666

We report e+e- --> b anti-b cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the PEP-II e+e- collider. A total relative error of about 5% is reached in more than three hundred center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Y(10860) and Y(11020) resonances. In particular we show that their widths may be smaller than previously measured.

1 data table

Measured values of R(b) from the detailed scan in SQRT(S),. where R(b) is the ratio between the number of observed E+ E- --> B BBAR(GAMMA) normalized to luminosity divided to the bare dimuon cross-section.


Study of Charm Fragmentation into $D^{*\pm}$ Mesons in Deep-Inelastic Scattering at HERA

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Eur.Phys.J.C 59 (2009) 589-606, 2009.
Inspire Record 792603 DOI 10.17182/hepdata.45316

The process of charm quark fragmentation is studied using $D^{*\pm}$ meson production in deep-inelastic scattering as measured by the H1 detector at HERA. Two different regions of phase space are investigated defined by the presence or absence of a jet containing the $D^{*\pm}$ meson in the event. The parameters of fragmentation functions are extracted for QCD models based on leading order matrix elements and DGLAP or CCFM evolution of partons together with string fragmentation and particle decays. Additionally, they are determined for a next-to-leading order QCD calculation in the fixed flavour number scheme using the independent fragmentation of charm quarks to $D^{*\pm}$ mesons.

20 data tables

Normalised D*+- cross section as a function of zJet for the D*+- jet sample.

Normalised D*+- cross section as a function of zHem for the D*+- jet sample.

Normalised D*+- cross section, corrected to the parton level, as a function of zJet for the D*+- jet sample.

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Measurement of the Proton Structure Function $F_L$ at Low x

The H1 collaboration Aaron, F.D. ; Alexa, C. ; Andreev, V. ; et al.
Phys.Lett.B 665 (2008) 139-146, 2008.
Inspire Record 786161 DOI 10.17182/hepdata.45340

A first measurement is reported of the longitudinal proton structure function F_L(x,Q^2) at the ep collider HERA. It is based on inclusive deep inelastic e^+p scattering cross section measurements with a positron beam energy of 27.5 GeV and proton beam energies of 920, 575 and 460 GeV. Employing the energy dependence of the cross section, F_L is measured in a range of squared four-momentum transfers 12 &lt; Q^2 &lt; 90 GeV^2 and low Bjorken x 0.00024 &lt; x &lt; 0.0036. The F_L values agree with higher order QCD calculations based on parton densities obtained using cross section data previously measured at HERA.

9 data tables

The measured longitudinal proton structure function FL at Q**2 = 12 GeV**2 extracted from the combined 920,575 and 450 GeV proton energy data.

The measured longitudinal proton structure function FL at Q**2 = 15 GeV**2 extracted from the combined 920,575 and 450 GeV proton energy data.

The measured longitudinal proton structure function FL at Q**2 = 20 GeV**2 extracted from the combined 920,575 and 450 GeV proton energy data.

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Study of the Exclusive Initial-State-Radiation Production of the DDbar System

The BaBar collaboration Aubert, Bernard ; Bona, M. ; Boutigny, D. ; et al.
SLAC-PUB-12818, 2008.
Inspire Record 776519 DOI 10.17182/hepdata.18803

A search for charmonium and other new states is performed in a study of exclusive initial-state-radiation production of D Dbar events from electron-positron annihilations at a center-of-mass energy of 10.58 GeV. The data sample corresponds to an integrated luminosity of 384 fb-1 and was recorded by the BABAR experiment at the PEP-II storage ring. The D Dbar mass spectrum shows clear evidence of the psi(3770) plus other structures near 3.9, 4.1, and 4.4 GeV/c^2. No evidence for Y(4260) -> D Dbar is observed, leading to an upper limit of B(Y(4260) -> D Dbar)/B(Y(4260) -> J/psi pi+ pi-) < 1.0 at 90 % confidence level.

1 data table

Measured cross section for D0 DBAR0 and D+ D- production. Bins with no data are shown with a 'dash'.


Measurement of isolated photon production in deep-inelastic scattering at HERA

The H1 collaboration Aaron, F.D. ; Aktas, A. ; Alexa, C. ; et al.
Eur.Phys.J.C 54 (2008) 371-387, 2008.
Inspire Record 768933 DOI 10.17182/hepdata.45424

The production of isolated photons in deep-inelastic scattering $ep\to e \gamma X$ is measured with the H1 detector at HERA. The measurement is performed in the kinematic range of negative four-momentum transfer squared $4&lt;Q^2&lt;150 $~GeV$^2$ and a mass of the hadronic system $W_X>50$ GeV. The analysis is based on a total integrated luminosity of 227~pb$^{-1}$. The production cross section of isolatedphotons with a transverse energy in the range $3 &lt; E_T^\gamma &lt; 10$ GeV and pseudorapidity range $-1.2 &lt; \eta^\gamma &lt; 1.8$ is measured as a function of $E_T^\gamma$, $\eta^\gamma$ and $Q^2$. Isolated photon cross sections are also measured for events with no jets or at least one hadronic jet. The measurements are compared with predictions from Monte Carlo generators modelling the photon radiation from the quark and the electron lines, as well as with calculations at leading and next to leading order in the strong coupling. The predictions significantly underestimate the measured cross sections.

15 data tables

Measured inclusive isolated photon cross section.

Measured total cross section for isolated photons plus no-jets and 1-jet.

Differential cross section as a function of the photon ET.

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Three- and Four-jet Production at Low x at HERA

The H1 collaboration Aaron, F.D. ; Aktas, A. ; Alexa, C. ; et al.
Eur.Phys.J.C 54 (2008) 389-409, 2008.
Inspire Record 767896 DOI 10.17182/hepdata.45429

Three- and four-jet production is measured in deep-inelastic $ep$ scattering at low $x$ and $Q^2$ with the H1 detector using an integrated luminosity of $44{.}2 {\rm pb}^{-1}$. Several phase space regions are selected for the three-jet analysis in order to study the underlying parton dynamics from global topologies to the more restrictive regions of forward jets close to the proton direction. The measurements of cross sections for events with at least three jets are compared to fixed order QCD predictions of ${\mathcal{O}}(\alpha_{\rm s}^2)$ and ${\mathcal{O}}(\alpha_{\rm s}^3) $ and with Monte Carlo simulation programs where higher order effects are approximated by parton showers. A good overall description is provided by the ${\mathcal{O}}(\alpha_{\rm s}^3) $ calculation. Too few events are predicted at the lowest $x \sim 10^{-4}$, especially for topologies with two forward jets. This hints to large contributions at low $x$ from initial state radiation of gluons close to the proton direction and unordered in transverse momentum. The Monte Carlo program in which gluon radiation is generated by the colour dipole model gives a good description of both the three- and the four-jet data in absolute normalisation and shape.

23 data tables

Differential cross section as a function of the minimum number of jet for events with at least 3-jets.

Differential cross section as a function of X for events with at least 3-jets.

Differential cross section for events with at least 3-jets as a function of the pseudorapidity of each jet.

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Measurements of e+ e- ---> K+ K- eta, K+ K- pi0 and K0(s) K+- pi-+ cross- sections using initial state radiation events

The BaBar collaboration Aubert, Bernard ; Bona, M. ; Boutigny, D. ; et al.
Phys.Rev.D 77 (2008) 092002, 2008.
Inspire Record 765258 DOI 10.17182/hepdata.50372

This paper reports measurements of processes: e+e- -> gamma KsK+pi-, e+e- -> gamma K+K-pi0, e+e- -> gamma phi eta, and e+e- -> gamma phi pi0. The initial state radiated photon allows to cover the hadronic final state in the energy range from thresholds up to ~4.6 GeV. The overall size of the data sample analyzed is 232 fb-1, collected by the BaBar detector running at the PEP-II e+e- storage ring. From the Dalitz plot analysis of the KsK+pi- final state, moduli and relative phase of the isoscalar and the isovector components of the e+e- -> K K*(892) cross section are determined. Parameters of phi and rho recurrences are also measured, using a global fitting procedure which exploits the interconnection among amplitudes, moduli and phases of the e+e- -> KsK+pi-, K+K-pi0, phi eta final states. The cross section for the OZI-forbidden process e+e- -> phi pi0, and the J/psi branching fractions to KK*(892) and K+K-eta are also measured.

9 data tables

The cross section for E+ E- --> K0S K+ PI- + CC with statistical errors only.

The cross section for E+ E- --> K+ K- PI0 with statistical errors only.

The cross section for E+ E- --> PHI PI0 with statistical errors only.

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