Production of $\Lambda$ hyperons in inelastic p+p interactions at 158 GeV/$c$

The NA61/SHINE collaboration Aduszkiewicz, A. ; Ali, Y. ; Andronov, E. ; et al.
Eur.Phys.J.C 76 (2016) 198, 2016.
Inspire Record 1397634 DOI 10.17182/hepdata.76910

Inclusive production of $\Lambda$-hyperons was measured with the large acceptance NA61/SHINE spectrometer at the CERN SPS in inelastic p+p interactions at beam momentum of 158~\GeVc. Spectra of transverse momentum and transverse mass as well as distributions of rapidity and x$_{_F}$ are presented. The mean multiplicity was estimated to be $0.120\,\pm0.006\;(stat.)\,\pm 0.010\;(sys.)$. The results are compared with previous measurements and predictions of the EPOS, UrQMD and FRITIOF models.

6 data tables

Double-differential yield $\frac{d^2n}{dydp_{_T}}$.

Double-differential yield $\frac{d^2n}{dydm_{_T}}$.

Double-differential yields, $\frac{d^{2}n}{x_{_F}p_{_T}}$ and $f_n(x_{_F},p_{T})$, for $x_{_F}<0$.

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Dimuon production in collisions of proton, oxygen and sulfur ions on heavy targets at 200 GeV/nucleon; $J/\psi$ production, $\pi$ and $K$ distributions

The NA38 collaboration Grossiord, J.Y. ; Abreu, M.C. ; Alimi, M. ; et al.
Nucl.Phys.A 498 (1989) 249-260, 1989.
Inspire Record 1392869 DOI 10.17182/hepdata.36947

The dimuon production in 200 GeV/nucleon O-U, O-Cu, S-U and p-U reactions is studied in function of transverse energy E T produced by the collision. The J / ψ production relative to continuum events is suppressed for heavy ion induced reactions when E T increases. This suppression is enhanced at low transverse momentum. The π and K meson distributions extracted from the data, have, for each reaction, a similar average transverse momentum which increases only slightly with the transverse energy.

3 data tables

No description provided.

No description provided.

No description provided.


Impact parameter dependence of high-energy gamma-ray production in argon induced reaction at 85 MeV/nucleon

Njock, M. Kwato ; Maurel, M. ; Monnand, E. ; et al.
Nucl.Phys.A 489 (1988) 368-380, 1988.
Inspire Record 1389759 DOI 10.17182/hepdata.37000

The double-differential cross sections for high-energy γ-rays were measured for collisions of 36Ar on C, Al, Cu, Ag, Tb, and Au at 85 MeV/nucleon. The system 36Ar+ 27Al has been studied in more detail in an exclusive experiment where the charged-particle multiplicity was measured in coincidence with high-energy γ-rays. A clear correlation between the hardness of the γ-spectra and the overlap distance of the two ions is observed. This correlation is interpreted as due to the spatial dependence of the Fermi momentum of the nucleons.

2 data tables

No description provided.

No description provided.


$K^- p$ elastic scattering at 2.24 GeV/c

Dickinson, M. ; Miyashita, S. ; Libby, L.Marshall ; et al.
Phys.Lett.B 24 (1967) 596-598, 1967.
Inspire Record 1389623 DOI 10.17182/hepdata.29569

The differential elastic scattering cross section for 2.24 GeV/ c K − p collisions has been measured in film from the Brookhaven 20″ bubble chamber. The total elastic cross section is found to be 6.2 ± 0.7 mb. The exponential dependence on square of the momentum t in (GeV/ c ) 2 is fitted by ( d σ d Ω elastic = (12.4 ± 1.0 mb/sr) exp (7.81 ± 0.25)t . A A fit to a black disc model requires a radius of 0.95 ± 0.05 fm.

1 data table

D(SIG)/D(T) was fitted to CONST*EXP(-SLOPE*T).


Exclusive $\rho^0$ Meson Photoproduction with a Leading Neutron at HERA

The H1 collaboration Andreev, V. ; Baghdasaryan, A. ; Begzsuren, K. ; et al.
Eur.Phys.J.C 76 (2016) 41, 2016.
Inspire Record 1387751 DOI 10.17182/hepdata.74219

A first measurement is presented of exclusive photoproduction of $\rho^0$ mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years $2006$ and $2007$ at a centre-of-mass energy of $\sqrt{s}=319$ GeV and correspond to an integrated luminosity of $1.16$ pb$^{-1}$. The $\rho^0$ mesons with transverse momenta $p_T<1$ GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, $x_L>0.35$, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality $Q^2 < 2$ GeV$^2$, the total energy of the photon-proton system $20 < W_{\gamma p} < 100$ GeV and the polar angle of the leading neutron $\theta_n < 0.75$ mrad. The cross section of the reaction $\gamma p \to \rho^0 n \pi^+$ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a $\rho^0$ meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, $\sigma^{\rm el}(\gamma\pi^+ \to \rho^0\pi^+)$, is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction $\gamma p\to\rho^0 n \pi^+$.

11 data tables

The $\gamma p$ cross section integrated in the domain $0.35 < x_L < 0.95$ and $-t^\prime < 1$~GeV$^2$ and averaged over the energy range $20 < W_{\gamma p} < 100$ GeV for two intervals of leading neutron transverse momentum.

Differential photoproduction cross sections ${\rm d}\sigma_{\gamma p}/{\rm d}x_L$ for the exclusive process $\gamma p \to \rho^0 n \pi^+$ in two regions of neutron transverse momentum and $20 < W_{\gamma p} < 100$ GeV. The statistical, uncorrelated and correlated systematic uncertainties, $\delta_{stat}$, $\delta_{sys}^{unc}$ and $\delta_{sys}^{cor}$ respectively, are given, which does not include the global normalisation error of $4.4\%$.

Double differential photoproduction cross sections ${\rm d^2}\sigma_{\gamma p}/{\rm d}x_L{\rm d}p_{T,n}^2$ in the range $20 < W_{\gamma p} < 100$ GeV. The statistical, uncorrelated and correlated systematic uncertainties, $\delta_{stat}$, $\delta_{sys}^{unc}$ and $\delta_{sys}^{cor}$ respectively, are given, which does not include the global normalisation error of $4.4\%$.

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Observation of charge asymmetry dependence of pion elliptic flow and the possible chiral magnetic wave in heavy-ion collisions

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Rev.Lett. 114 (2015) 252302, 2015.
Inspire Record 1358666 DOI 10.17182/hepdata.72237

We present measurements of $\pi^-$ and $\pi^+$ elliptic flow, $v_2$, at midrapidity in Au+Au collisions at $\sqrt{s_{_{\rm NN}}} =$ 200, 62.4, 39, 27, 19.6, 11.5 and 7.7 GeV, as a function of event-by-event charge asymmetry, $A_{ch}$, based on data from the STAR experiment at RHIC. We find that $\pi^-$ ($\pi^+$) elliptic flow linearly increases (decreases) with charge asymmetry for most centrality bins at $\sqrt{s_{_{\rm NN}}} = \text{27 GeV}$ and higher. At $\sqrt{s_{_{\rm NN}}} = \text{200 GeV}$, the slope of the difference of $v_2$ between $\pi^-$ and $\pi^+$ as a function of $A_{ch}$ exhibits a centrality dependence, which is qualitatively similar to calculations that incorporate a chiral magnetic wave effect. Similar centrality dependence is also observed at lower energies.

10 data tables

The distribution of observed charge asymmetry from STAR data.

Pion $v_2${2} as a function of observed charge asymmetry.

$v_2$ difference between $\pi^-$ and $\pi^+$ as a function of charge asymmetry with the tracking efficiency correction, for 30-40% central Au+Au collisions at 200 GeV. The errors are statistical only.

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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.C 92 (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 RHIC. Systematic measurements of the dielectron yield as a function of transverse momentum ($p_{\rm T}$) and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region ($M_{ee}<$ 1 GeV/$c^2$). This enhancement cannot be reproduced by the $\rho$-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of 0.30 $-$ 0.76 GeV/$c^2$, integrated over the full $p_{\rm T}$ acceptance, the enhancement factor is 1.76 $\pm$ 0.06 (stat.) $\pm$ 0.26 (sys.) $\pm$ 0.29 (cocktail). The enhancement factor exhibits weak centrality and $p_{\rm T}$ 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 $\pm$ 0.10. Models that assume an in-medium broadening of the $\rho$ meson spectral function consistently describe the observed excess in these measurements. Additionally, we report on measurements of $\omega$ and $\phi$-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 $\phi$-meson, results through its $K^+K^-$ decay channel. In the intermediate invariant-mass region (1.1$<M_{ee}<$ 3 GeV/$c^2$), 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 proton-proton elastic scattering and total cross-section at S**(1/2) = 7-TeV

The TOTEM collaboration Antchev, G. ; Aspell, P. ; Atanassov, I. ; et al.
EPL 101 (2013) 21002, 2013.
Inspire Record 1220862 DOI 10.17182/hepdata.66456

At the LHC energy of $\sqrt s = 7\,{\mathrm { TeV}}$ , under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam center (≈5σ(beam)) in a dedicated run with β* = 90 m, |t|-values down to 5·10(−)(3) GeV(2) were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B = (19.9 ± 0.3) GeV(−)(2) over the large |t|-range from 0.005 to 0.2 GeV(2) describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t = 0. With the luminosity from CMS, the elastic cross-section was determined to be (25.4 ± 1.1) mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6 ± 2.2) mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al), EPL, 95 (2011) 41001).

5 data tables

The measured differential elastic cross section.

The measured differential elastic cross section in the high |T| region. where it originally appeared as a plot, but was not tabulated.

The fitted slope parameter for the elastic cross section fitted over 4 |T| ranges.

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Measurement of the reaction $\gamma p \TO K^ + \Lambda(1520)$ at photon energies up to 2.65 GeV

Wieland, F.W. ; Barth, J. ; Glander, K.H. ; et al.
Eur.Phys.J.A 47 (2011) 47, 2011.
Inspire Record 875422 DOI 10.17182/hepdata.57580

The reaction $\gamma p \TO K^+\Lambda(1520)$ was measured in the energy range from threshold to 2.65 GeV with the SAPHIR detector at the electron stretcher facility ELSA in Bonn. The $\Lambda(1520)$ production cross section was analyzed in the decay modes $pK^-$, $n \bar{K}^0$, $\Sigma^{\pm}\pi^{\mp}$, and $\Lambda\pi^+\pi^-$ as a function of the photon energy and the squared four-momentum transfer $t$. While the cross sections for the inclusive reactions rise steadily with energy, the cross section of the process $\gamma p \TO K^+\Lambda(1520)$ peaks at a photon energy of about 2.0 GeV, falls off exponentially with $t$, and shows a slope flattening with increasing photon energy. The angular distributions in the $t$-channel helicity system indicate neither a $K$ nor a $K^\star$ exchange dominance. The interpretation of the $\Lambda(1520)$ as a $\Sigma(1385)\pi$ molecule is not supported.

7 data tables

Total cross section averaged over the various LAMBDA(1510) decay modes. The errors are largely due to the systematic error in the background subtraction.

Total cross section determined for each of the separated decay modes of the LAMBDA(1510).

Differential cross sections for the photon energy range 1.69 TO 1.93 GeV. The errors are lapping due to the systematic error in the background subtraction.

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Diffractive Electroproduction of rho and phi Mesons at HERA

The H1 collaboration Aaron, F.D. ; Aldaya Martin, M. ; Alexa, C. ; et al.
JHEP 05 (2010) 032, 2010.
Inspire Record 835609 DOI 10.17182/hepdata.56191

Diffractive electroproduction of rho and phi mesons is measured at HERA with the H1 detector in the elastic and proton dissociative channels. The data correspond to an integrated luminosity of 51 pb^-1. About 10500 rho and 2000 phi events are analysed in the kinematic range of squared photon virtuality 2.5 &lt; Q^2 &lt; 60 GeV^2, photon-proton centre of mass energy 35 &lt; W &lt; 180 GeV and squared four-momentum transfer to the proton |t| &lt; 3 GeV^2. The total, longitudinal and transverse cross sections are measured as a function of Q^2, W and |t|. The measurements show a transition to a dominantly "hard" behaviour, typical of high gluon densities and small q\bar{q} dipoles, for Q^2 larger than 10 to 20 GeV^2. They support flavour independence of the diffractive exchange, expressed in terms of the scaling variable (Q^2 + M_V^2)/4, and proton vertex factorisation. The spin density matrix elements are measured as a function of kinematic variables. The ratio of the longitudinal to transverse cross sections, the ratio of the helicity amplitudes and their relative phases are extracted. Several of these measurements have not been performed before and bring new information on the dynamics of diffraction in a QCD framework. The measurements are discussed in the context of models using generalised parton distributions or universal dipole cross sections.

108 data tables

Q**2 dependence of the GAMMA* P elastic RHO0 meson production at mean W There is an additional overall normalization uncertainty of 3.9 PCT.

Q**2 dependence of the GAMMA* P cross section for proton dissociative RHO0 meson production at mean W There is an additional overall normalization uncertainty of 4.6 PCT.

Q**2 dependence of the GAMMA* P elastic PHI meson production at mean W There is an additional overall normalization uncertainty of 4.7 PCT.

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