Charm production in antiproton–nucleus collisions at the J/ψ and the ψ′ thresholds (original) (raw)
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Charm production in antiproton–nucleus collisions at the and the thresholds
Physics Letters B, 2005
We discuss the production of charmonium states in antiproton-nucleus collisions at the ψ threshold. It is explained that measurements inpA collisions will allow to get new information about the strengths of the inelastic J/ψN and ψ N interaction, on the production of Λ c andD in charmonium-nucleon interactions and for the first time about the nondiagonal transitions ψ N → J/ψN. The inelastic J/ψ-nucleon cross section is extracted from the comparison of hadron-nucleus collisions with hadron-nucleon collisions. We extract the total J/ψ-nucleon cross section from photon-nucleon collisions by accounting for the color transparency phenomenon within the frame of the GVDM (generalized vector meson dominance model). We evaluate within the GVDM the inelastic ψ -nucleon cross section as well as the cross section for the nondiagonal transitions. Predictions for the ratio of J/ψ to ψ yields in antiproton-nucleus scatterings close to the threshold of ψ production for different nuclear targets are presented.
Charmonium production in antiproton-nucleus reactions at low energies
Physical Review C, 2013
The J/Ψ(1S) and Ψ ′ (2S) production near threshold in antiproton-nucleus reactions is calculated on the basis of the Glauber model. The model takes into account the antiproton (pre)absorption, proton Fermi motion, and charmonium formation length. We confirm earlier prediction that the charmonium production inpA collisions at p lab = 3 − 10 GeV/c is not influenced by formation length effects and is very well suited to determine the genuine charmonium-nucleon dissociation cross sections. The comparison is performed with the J/Ψ photoproduction at high energies, where formation length effects play a very important role. However, we demonstrate that the detailed structure of the proton and neutron density profiles has to be taken into account, if one wants to extract information on the J/ΨN dissociation cross section from J/Ψ transparency ratios. These studies are relevant for the upcoming PANDA experiment at FAIR.
A quantitative analysis of charmonium suppression in nuclear collisions
European Physical Journal C, 1997
Data from J/ψ and ψ′ production in p - A collisions are used to determine the cross section for absorption of pre-resonance charmonium in nuclear matter. The J/ψ suppression in O - Cu, O - U and S - U collisions is fully reproduced by the corresponding nuclear absorption, while Pb - Pb collisions show an additional suppression increasing with centrality. We study the onset of this change in terms of hadronic comover interactions and conclude that so far no conventional hadronic description can consistently account for all data. Deconfinement, starting at a critical point determined by central S - U collisions, is in accord with the observed suppression pattern.
Color Deconfinement and Charmonium Production in Nuclear Collisions
Landolt-Börnstein - Group I Elementary Particles, Nuclei and Atoms, 2010
In statistical QCD, color deconfinement and the properties of the quark-gluon plasma determine the in-medium behavior of heavy quark bound states. In high energy nuclear collisions, charmonia probe the partonic medium produced in the early stages of the interaction. We survey the present theoretical status and provide a critical evaluation of the charmonium production measurements in experiments at the CERN-SPS and the BNL-RHIC.
Color screening and the suppression of the charmonium state yield in nuclear reactions
Physical Review C, 2004
We discuss the new data for the production of the ψ ′ meson in pA collisions at 450 GeV at CERN-SPS (of the NA50-collaboration) [1]. We extract from the CERN data σ(ψ ′ N ) ≈ 8 mb under the assumption that the ψ ′ is produced as a result of the space-time evolution of a point-like cc pair which expands with time to the full size of the charmonium state. In the analysis we assume the existence of a relationship between the distribution of color in a hadron and the cross section of its interaction with a nucleon. However, our result is rather sensitive to the pattern of the expansion of the wave packet and significantly larger values of σ(ψ ′ N ) are not ruled out by the data. We show that recent CERN data confirm the suggestion of ref.
2009
In CDF we have observed the reactions p þ" p! p þ X þ" p, with X being a centrally produced J= c, cð2SÞ, or c0, and! þ À in p" p collisions at ffiffiffi sp ¼ 1: 96 TeV. The event signature requires two oppositely charged central muons, and either no other particles or one additional photon detected. Exclusive vector meson production is as expected for elastic photoproduction, þ p! J= cðcð2SÞÞ þ p, observed here for the first time in hadron-hadron collisions. We also observe exclusive c0! J= c þ.
J/ψ Suppression in Nucleus-Nucleus Collisions
Physical Review Letters, 2002
We propose a model for the production and suppression of J/ψ mesons in high-energy hadronic collisions. We factorized the process into a production of the cc pairs of relative momentum k = k c − kc convoluted with a transition probability from the produced cc pairs into the observed J/ψ mesons. As the produced cc pairs exit the nuclear matter, the multiple scattering between the colored c andc and the nuclear medium increases the square of the relative momentum between the c andc, q 2 = −k 2 , such that some of the cc pairs gain enough invariant mass to transmute into open charm states. With only one parameter, the amount of energy gained by the produced cc pair per unit length in the nuclear medium, our model can fit all observed J/ψ suppression data including recent NA50 data from Pb-Pb collisions.
Observation of charmonium pairs produced exclusively in pppppp collisions
Journal of Physics G-Nuclear and Particle Physics, 2014
A search is performed for the central exclusive production of pairs of charmonia produced in proton-proton collisions. Using data corresponding to an integrated luminosity of 3 fb −1 collected at centre-of-mass energies of 7 and 8 TeV, J/ψJ/ψ and J/ψψ(2S) pairs are observed, which have been produced in the absence of any other activity inside the LHCb acceptance that is sensitive to charged particles in the pseudorapidity ranges (−3.5, −1.5) and (1.5, 5.0). Searches are also performed for pairs of P-wave charmonia and limits are set on their production. The cross-sections for these processes, where the dimeson system has a rapidity between 2.0 and 4.5, are measured to be σ J/ψ J/ψ = 58 ± 10(stat) ± 6(syst) pb, σ J/ψ ψ(2S) = 63 +27 −18 (stat) ± 10(syst) pb, σ ψ(2S)ψ(2S) < 237 pb, σ χ c0 χ c0 < 69 nb, σ χ c1 χ c1 < 45 pb, σ χ c2 χ c2 < 141 pb,
Charmonium suppression in heavy ion collisions by prompt gluons
Physics Letters B, 1998
In relativistic heavy ion collisions, also the bremsstrahlung of gluons in the fragmentation regions of the nuclei suppresses the produced charmonium states. In the energy range of the SPS, the radiation of semi-hard gluons occurs in the Bethe-Heitler regime and the density of gluons and therefore the suppression goes like (AB) 1 3 , where A and B are the nucleon numbers of the projectile and target nuclei. In contrast, the suppression via collisions with nucleons is proportional to (A 1 3 + B 1 3). Parameter free perturbative QCD calculations are in a good agreement with the data on J/Ψ and Ψ suppression in heavy ion collisions at SPS CERN. At higher energies (RHIC, LHC) the number of gluons which are able to break-up the charmonium substantially decreases and the additional suppression is expected to vanish. Challenges in charmonium production off nuclei Charmonium production in heavy ion collisions is considered as one of several sensitive probes for the formation of a quark-gluon plasma [1]. This idea has led the NA38 and NA50 collaborations at SPS CERN to perform a series of measurements of nuclear suppression for charmonium production in p A and A B collisions. We recall some remarkable observations (see the collection of data in [2]): (i) If J/Ψ suppression in proton-nucleus collisions is treated as a final state absorption phenomenon one extracts an absorption cross section σ in (J/Ψ N) ≈ 6 − 7 mb from the data. At the same time, the vector dominance model applied to J/Ψ photoproduction data on protons results in a much smaller value σ tot (J/Ψ N) ≈ 1.1 mb, which increases to a value of 3 − 4 mb for a coupled-channel analysis of the photoproduction data [3]. However, a