Observation of a New Isoscalar Vector Meson in $e^+ e^- \to \omega \pi^+ \pi^-$ Annihilation at 1.65-{GeV}

Cordier, A. ; Bisello, D. ; Bizot, J.C. ; et al.
Phys.Lett.B 106 (1981) 155-158, 1981.
Inspire Record 166964 DOI 10.17182/hepdata.31042

The e + e − → ωπ + π − → π + π − π + π − π 0 cross section has been measured at DCI by the DMI experiment in the 1.4–2.2 GeV energy range. A bump in this cross section appears at 1.65 GeV above a small background, with 6.2 s.d. statistical significance. It can be interpreted as a new isoscalar vector meson: ω ′ or ø ′.

1 data table

THE INDIVIDUAL SYSTEMATIC ERRORS ARISE FROM THE UNCERTAINTY IN SUBTRACTING THE FIVE-PION (NON-OMEGA) BACKGROUND. THESE ERRORS ARE CORRELATED WITH THE STATISTICAL ERRORS.


Study of the Reaction $e^+ e^- \to K^+ K^-$ in the Energy Range 1350 $\le \sqrt{s} \le$ 2400-{MeV}

The DM2 collaboration Bisello, D. ; Busetto, G. ; Castro, A. ; et al.
Z.Phys.C 39 (1988) 13, 1988.
Inspire Record 262690 DOI 10.17182/hepdata.15622

Thee+e−→K+K− cross section has been measured from about 750 events in the energy interval\(1350 \leqq \sqrt s\leqq 2400 MeV\) with the DM2 detector at DCI. TheK± form factor |FF±| cannot be explained by the ρ, ω, ϕ and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment.

2 data tables

No description provided.

No description provided.


Measurement of the e+ e- ---> pi+ pi- pi0 and e+ e- ---> omega pi+ pi- reactions in the energy interval 1350-MeV - 2400-MeV

The DM2 collaboration Antonelli, A. ; Baldini, R. ; Biagini, M.E. ; et al.
Z.Phys.C 56 (1992) 15-20, 1992.
Inspire Record 339265 DOI 10.17182/hepdata.14555

The cross sections fore+e−→π+π−π0 ande+e−→ωπ+π− have been measured in the 1.35 ≦\(\sqrt s \) ≦2.4 GeV range from 1900 nb−1 collected by DM2 at DCI. The second process proceeds via a resonant state at ≈- 1660 MeV/c2, ≈- 280 MeV/c2 wide. The first one is larger than a VDM extrapolation from the ω-ϕ peaks and, although does not show any clear structure, is compatible with the presence of the above resonance.

2 data tables

No description provided.

No description provided.


Study of the eta(c) (s wave singlet) state of charmonium formed in anti-p p annihilations and a search for the eta(c)-prime (s wave doublet)

The E760 collaboration Armstrong, T.A. ; Bettoni, D. ; Bharadwaj, V. ; et al.
Phys.Rev.D 52 (1995) 4839-4854, 1995.
Inspire Record 395314 DOI 10.17182/hepdata.42381

The E760 Collaboration performed an experiment in the Antiproton Accumulator at Fermilab to study the two photon decay of the ηc(1 1S0) charmonium state formed in p¯p annihilations. This resulted in a new measurement of the mass Mηc=2988.3−3.1+3.3 MeV/c2 and of the product B(ηc→p¯p)×Γ(ηc→γγ) =(8.1−2.0+2.9) eV. We performed a search for the process p¯p→ηc′(2 1S0)→γγ over a limited range of center-of-mass energies. Since no signal was observed, we derived upper limits on the product of branching ratios B(ηc′→p¯p)×B(ηc′→γγ) in the center-of-mass energy range 3584≤ √s ≤3624 MeV. We observed no signal for the nonresonant process p¯+p→γ+γ and obtain upper limits.

2 data tables

No description provided.

No description provided.


Midrapidity antiproton-to-proton ratio in pp collisions at $\sqrt{s} = 0.9$ and $7$~TeV measured by the ALICE experiment

The ALICE collaboration Aamodt, K. ; Abel, N. ; Abeysekara, U. ; et al.
Phys.Rev.Lett. 105 (2010) 072002, 2010.
Inspire Record 859610 DOI 10.17182/hepdata.55557

The ratio of the yields of antiprotons to protons in pp collisions has been measured by the ALICE experiment at $\sqrt{s} = 0.9$ and $7$ TeV during the initial running periods of the Large Hadron Collider(LHC). The measurement covers the transverse momentum interval $0.45 < p_{\rm{t}} < 1.05$ GeV/$c$ and rapidity $|y| < 0.5$. The ratio is measured to be $R_{|y| < 0.5} = 0.957 \pm 0.006 (stat.) \pm 0.014 (syst.)$ at $0.9$ TeV and $R_{|y| < 0.5} = 0.991 \pm 0.005 (stat.) \pm 0.014 (syst.)$ at $7$ TeV and it is independent of both rapidity and transverse momentum. The results are consistent with the conventional model of baryon-number transport and set stringent limits on any additional contributions to baryon-number transfer over very large rapidity intervals in pp collisions.

2 data tables

The PT dependence of the pbar/p ratio for the central rapidity region ABS(YRAP)<0.5.

The central rapidity pbar/p ratio as a function of the rapidity interval Ybeam-Ybaryon and centre-of-mass energy. As well as the present ALICE measurements this table also lists the values from other experiments (see the text of the paper for details).


Initial-State Radiation Measurement of the e+e- -> pi+pi-pi+pi- Cross Section

The BaBar collaboration Lees, J.P. ; Poireau, V. ; Tisserand, V. ; et al.
Phys.Rev.D 85 (2012) 112009, 2012.
Inspire Record 1086164 DOI 10.17182/hepdata.57561

We study the process e+e- -> pi+pi-pi+pi-gamma, with a photon emitted from the initial-state electron or positron, using 454.3 fb^-1 of data collected with the BABAR detector at SLAC, corresponding to approximately 260,000 signal events. We use these data to extract the non-radiative sigma(e+e- ->pi+pi-pi+pi-) cross section in the energy range from 0.6 to 4.5 Gev. The total uncertainty of the cross section measurement in the peak region is less than 3%, higher in precision than the corresponding results obtained from energy scan data.

1 data table

The dressed and undressed cross sections for the reaction E+ E- --> PI+ PI- PI+ PI-. Statistical errors only.


Measurement of the inclusive differential jet cross section in pp collisions at sqrt{s} = 2.76 TeV

The ALICE collaboration Abelev, B. ; Adam, J. ; Adamova, D. ; et al.
Phys.Lett.B 722 (2013) 262-272, 2013.
Inspire Record 1210881 DOI 10.17182/hepdata.60430

The ALICE collaboration at the CERN Large Hadron Collider reports the first measurement of the inclusive differential jet cross section at mid-rapidity in pp collisions at $\sqrt{s} = 2.76$ TeV, with integrated luminosity of 13.6 nb$^{-1}$. Jets are measured over the transverse momentum range 20 to 125 GeV/c and are corrected to the particle level. Calculations based on Next-to-Leading Order perturbative QCD are in good agreement with the measurements. The ratio of inclusive jet cross sections for jet radii $R = 0.2$ and $R = 0.4$ is reported, and is also well reproduced by a Next-to-Leading Order perturbative QCD calculation when hadronization effects are included.

2 data tables

Inclusive differential jet cross section for R=0.2 and R=0.4.

Ratio of the inclusive differential jet cross section for R=0.2 and R=0.4.


Mid-rapidity anti-baryon to baryon ratios in pp collisions at sqrt(s) = 0.9, 2.76 and 7 TeV measured by ALICE

The ALICE collaboration Abbas, E. ; Abelev, B. ; Adam, J. ; et al.
Eur.Phys.J.C 73 (2013) 2496, 2013.
Inspire Record 1232209 DOI 10.17182/hepdata.61965

The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for $\bar{\rm p}/{\rm p}$, $\bar{\rm \Lambda}/{\rm \Lambda}$, $\rm\bar{\Xi}$$^{+}/{\rm \Xi}^{-}$ and $\rm\bar{\Omega}$$^{+}/{\rm \Omega}^{-}$ in pp collisions at $\sqrt{s} = 0.9$, 2.76 and 7 TeV, measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING-B, that are used to model the particle production in pp collisions. The energy dependence of $\bar{\rm p}/{\rm p}$, $\bar{\rm \Lambda}/{\rm \Lambda}$, $\rm\bar{\Xi}$$^{+}/{\rm \Xi^{-}}$ and $\rm\bar{\Omega}$$^{+}/{\rm \Omega^{-}}$, reaching values compatible with unity for $\sqrt{s} = 7$ TeV, complement the earlier $\bar{\rm p}/{\rm p}$ measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of $\alpha_{\rm {J}} \approx 0.5$, which are suppressed with increasing rapidity interval ${\rm \Delta} y$. Any significant contribution of an exchange not suppressed at large ${\rm \Delta} y$ (reached at LHC energies) is disfavoured.

20 data tables

The pbar/p ratio at sqrt(s) = 2.76 TeV as a function of pT.

The pbar/p ratio at sqrt(s) = 2.76 TeV as a function of rapidity.

The LambdaBar/Lambda ratio at sqrt(s) = 0.9 TeV as a function of pT.

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Measurement of charged jet suppression n Pb-Pb collisions at sqrt(sNN)=2.76TeV

The ALICE collaboration Abelev, B. ; Adam, J. ; Adamova, D. ; et al.
JHEP 03 (2014) 013, 2014.
Inspire Record 1263194 DOI 10.17182/hepdata.62723

A measurement of the transverse momentum spectra of jets in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV is reported. Jets are reconstructed from charged particles using the anti-$k_{\rm T}$ jet algorithm with jet resolution parameters $R$ of $0.2$ and $0.3$ in pseudo-rapidity $|\eta|<0.5$. The transverse momentum $p_{\rm T}$ of charged particles is measured down to $0.15$ GeV/$c$ which gives access to the low $p_{\rm T}$ fragments of the jet. Jets found in heavy-ion collisions are corrected event-by-event for average background density and on an inclusive basis (via unfolding) for residual background fluctuations and detector effects. A strong suppression of jet production in central events with respect to peripheral events is observed. The suppression is found to be similar to the suppression of charged hadrons, which suggests that substantial energy is radiated at angles larger than the jet resolution parameter $R=0.3$ considered in the analysis. The fragmentation bias introduced by selecting jets with a high $p_{\rm T}$ leading particle, which rejects jets with a soft fragmentation pattern, has a similar effect on the jet yield for central and peripheral events. The ratio of jet spectra with $R=0.2$ and $R=0.3$ is found to be similar in Pb-Pb and simulated PYTHIA pp events, indicating no strong broadening of the radial jet structure in the reconstructed jets with $R<0.3$.

30 data tables

Average values of the number of participating nucleons (Npart), number of binary collisions (Ncoll), and the nuclear overlap function (TAA) for the centrality intervals used in the jet analysis.

Charged jet spectra using two cone radius parameters R = 0.2 and 0.3 and a leading track selection of pT > 0.15 GeV, for centrality 0-10%. The two systematic uncertainties correspond to the shape uncertainty and the correlated uncertainty.

Charged jet spectra using two cone radius parameters R = 0.2 and 0.3 and a leading track selection of pT > 0.15 GeV, for centrality 10-30%. The two systematic uncertainties correspond to the shape uncertainty and the correlated uncertainty.

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Two-particle Bose-Einstein correlations in $pp$ collisions at $\mathbf {\sqrt{s} =}$ 0.9 and 7 TeV measured with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Eur.Phys.J.C 75 (2015) 466, 2015.
Inspire Record 1346844 DOI 10.17182/hepdata.70016

The paper presents studies of Bose-Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range $p_{\rm T}>$ 100 MeV and $|\eta|<$ 2.5 in proton--proton collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The integrated luminosities are approximately 7 $\mu$b$^{-1}$, 190 $\mu$b$^{-1}$ and 12.4 nb$^{-1}$ for 0.9 TeV, 7 TeV minimum-bias and 7 TeV high-multiplicity data samples, respectively. The multiplicity dependence of the BEC parameters characterizing the correlation strength and the correlation source size are investigated for charged-particle multiplicities of up to 240. A saturation effect in the multiplicity dependence of the correlation source size is observed using the high-multiplicity 7 TeV data sample. The dependence of the BEC parameters on the average transverse momentum of the particle pair is also investigated.

24 data tables

Systematic uncertainties on $\lambda$ and $R$ for the exponential fit of the two-particle double-ratio correlation function $R_{2}(Q)$ in the full kinematic region at $\sqrt{s} = 0.9$ and $7\ TeV$ for minimum-bias and high-multiplicity (HM) events, $n_{ch} \ge 2$ and $n_{ch} \ge 150$, respectively.

Results of fitting the multiplicity, $n_{ch}$, dependence of the BEC parameters $R$ and $\lambda$ with different functional forms for $\sqrt{s} = 0.9$ and $7\ TeV$. The $n_{ch}$ fit of $R(n_{ch})$ is applied to $7\ TeV$ minimum-bias events at $n_{ch} \le 55$ and to $0.9\ TeV$ minimum-bias events. The constant fit of $R(n_{ch} )$ is applied to $7\ TeV$ minimum-bias events for $n_{ch} > 55$ and to $7\ TeV$ high-multiplicity events. The exponential fit of $\lambda(n_{ch})$ is applied to $7\ TeV$ minimum-bias and high-multiplicity events.The error represent the quadratic sum of the statistical and systematic uncertainties.

Results of fitting the transverse momentum of the pair, $k_{T}$, dependence of the BEC parameters $R$ and $\lambda$ with the exponential fitting function for $\sqrt{s} = 0.9$ and $7\ TeV$. The error represent the quadratic sum of the statistical and systematic uncertainties.

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