Charmonia production in 450 GeV/c proton-induced reactions

Absolute \jpsi\ and \psip\ production cross sections have been measured at the CERN SPS, with 450~GeV/$c$ protons incident on a set of C, Al, Cu and W targets. Complementing these values with the results obtained by experiment NA51, which used the same beam and detector with H and D targets, we establish a coherent picture of charmonia production in proton-induced reactions at SPS energies. In particular, we show that the scaling of the \jpsi\ cross section with the mass number of the target, A, is well described as A$^\alpha$ with $\alpha^\psi=0.919\pm0.015$. The ratio between the \jpsi\ and \psip\ yields, in our kinematical window, is found to be independent of A, with $\alpha^{\psi^\prime}-\alpha^{\psi}=0.014\pm0.0 11$

Low mass dimuon production in proton and ion induced interactions at SPS

The low mass dimuon spectra collected in $p$-U collisions by the NA38 experiment significantly exceeds the total cross section expected from previous analysis, done by other experiments. The 'excess' events have a harder $p_{T}$ distribution than the muon pairs from $\eta$ and $\omega$ Dalitz decays, expected to dominate the mass window 0.4—0.65~GeV/$c^2$. We conjecture that the excess events might be due to $q\bar{q}$ annihilations, negligible at low $p_{T}$ but made visible by the $m_{T}$ cut applied in the NA38 data. Taking this assumption to parametrise the $p$-U spectra, we proceed with the analysis of the S-Cu, S-U and Pb-Pb data, collected by the NA38 and NA50 experiments, where we find that the measured mass spectra does not seem to exceed the expected low mass `cocktail' by more than 20%

Transverse momentum distributions of J/ψ\psi, ψ′\psi^{\prime}, Drell-Yan and continuum dimuons produced in Pb-Pb interactions at the SPS

Muon pairs produced in Pb-Pb interactions at 158~GeV/$c$ per nucleon are used to study the transverse momentum distributions of the J/$\psi$, $\psi^{\prime}$ and dimuons in the mass continuum. In particular, the dependence of these distributions on the centrality of the Pb-Pb collision is investigated in detail

Scaling of charged particle multiplicity in Pb-Pb collisions at SPS energies

The charged particle multiplicity distribution $dN_{ch}/d\eta$ has been measured by the NA50 experiment in Pb--Pb collisions at the CERN SPS. Measurements were done at incident energies of 40 and 158 GeV per nucleon over a broad impact parameter range. The multiplicity distributions are studied as a function of centrality using the number of participating nucleons ($N_{part}$), or the number of binary nucleon--nucleon collisions ($N_{coll}$). Their values at midrapidity exhibit a power law scaling behaviour given by $N_{part}^{1.00}$ and $N_{coll}^{0.75}$ at 158 GeV. Compatible results are found for the scaling behaviour at 40 GeV. The width of the $dN_{ch}/d\eta$ distributions is larger at 158 than at 40 GeV/nucleon and decreases slightly with centrality at both energies. Our results are compared to similar studies performed by other experiments both at the CERN SPS and at RHIC.

Results on Charmonium States in Pb-Pb Interactions

We present cross-sections for J/$\psi$, $\psi^{\prime}$ and Drell-Yan production in lead-lead interactions at 158 GeV/nucleon. The Pb-Pb data, when compared with previous results obtained with lighter target or projectiles, show a similar behaviour for Drell-Yan, but exhibit an anomalous J/$\psi$ suppression, which increases with centrality

Intermediate mass dimuons in NA38/NA50

The NA38/NA50 experiments have measured, at the CERN SPS, the dimuon production in proton-nucleus and nucleus-nucleus collisions. In this paper it is shown that the mass continuum between the $\phi$ and the $J/{\psi}$ can be satisfactorily described, after having removed the combinatorial background due to uncorrelated $\pi$ and $K$ decays, as a sum of two contributions, namely the Drell-Yan process and the semi-leptonic decay of pairs of charmed mesons, whose mass shape in the acceptance of the experiment has been evaluated using PYTHIA. However, in order to describe the A - B (namely S - U and Pb - Pb) mass spectra, the dimuon yield from open charm decays, which in $p$ - A collisions is found to be consistent with direct open charm measurements from other CERN and FNAL experiments, has to be enhanced with respect to a linear extrapolation of $p$ - A results. The size of the enhancement smoothly increases from peripheral S - U to central Pb - Pb interactions, reaching a factor $\sim$ 3 in central Pb - Pb collisions. The $P_{T}$ distributions of the events in the mass continuum are also compatible with the hypothesis of open charm enhancement in A - B collisions

Charmonia and Drell-Yan production in proton-nucleus collisions at the CERN SPS

Charmonium production in p-A collisions is a unique tool for the study of the interaction of bound ccbar in nuclear matter. It can provide details on the basic features of the resonance formation mechanism and, in particular, on its non-perturbative aspects. In this Letter, we present an experimental study of Charmonia and Drell-Yan production in proton-nucleus collisions at 450GeV/c. The results are analyzed in the framework of the Glauber model and lead to the values of the nuclear absorption cross-section sigma^abs_pA for j/psi and psi'. Then, we compare the J/psi absorption in proton-nucleus and sulphur-uranium interactions, using NA38 data. We obtain that, for the J/psi, omega^abs_pA and omega^abs_SU are compatible, showing that no sizeable additional suppression mechanism in present S-U collisions, and confirming that the anomalous J/psi suppression only sets in for Pb-Pb interactions

Rethinking European integration history in light of capitalism: the case of the long 1970s

This introduction outlines the possibilities and perspectives of an intertwining between European integration history and the history of capitalism. Although debates on capitalism have been making a comeback since the 2008 crisis, to date the concept of capitalism remains almost completely avoided by historians of European integration. This introduction thus conceptualizes ‘capitalism’ as a useful analytical tool that should be used by historians of European integration and proposes three major approaches for them to do so: first, by bringing the question of social conflict, integral to the concept of capitalism, into European integration history; second, by better conceptualizing the link between European governance, Europeanization and the globalization of capitalism; and thirdly by investigating the economic, political and ideological models or doctrines that underlie European cooperation, integration, policies and institutions. Finally, the introduction addresses the question of the analytical benefits of an encounter between capitalism and European integration history, focusing on the case of the 1970s. This allows us to qualify the idea of a clear-cut rupture, and better highlight how the shift of these years resulted from a complex bargaining that took place in part at the European level

Breeding Experience and the Heritability of Female Mate Choice in Collared Flycatchers

Heritability in mate preferences is assumed by models of sexual selection, and preference evolution may contribute to adaptation to changing environments. However, mate preference is difficult to measure in natural populations as detailed data on mate availability and mate sampling are usually missing. Often the only available information is the ornamentation of the actual mate. The single long-term quantitative genetic study of a wild population found low heritability in female mate ornamentation in Swedish collared flycatchers. One potentially important cause of low heritability in mate ornamentation at the population level is reduced mate preference expression among inexperienced individuals.Applying animal model analyses to 21 years of data from a Hungarian collared flycatcher population, we found that additive genetic variance was 50 percent and significant for ornament expression in males, but less than 5 percent and non-significant for mate ornamentation treated as a female trait. Female breeding experience predicted breeding date and clutch size, but mate ornamentation and its variance components were unrelated to experience. Although we detected significant area and year effects on mate ornamentation, more than 85 percent of variance in this trait remained unexplained. Moreover, the effects of area and year on mate ornamentation were also highly positively correlated between inexperienced and experienced females, thereby acting to remove difference between the two groups.The low heritability of mate ornamentation was apparently not explained by the presence of inexperienced individuals. Our results further indicate that the expression of mate ornamentation is dominated by temporal and spatial constraints and unmeasured background factors. Future studies should reduce unexplained variance or use alternative measures of mate preference. The heritability of mate preference in the wild remains a principal but unresolved question in evolutionary ecology