φ meson production in NA60

Arnaldi, R.; Averbeck, R.; Castor, J.; Chaurand, B.; Cicalò, C.; Colla, A.; Cortese, P.; Damjanović, S.; David, A.; Falco, A. De; Devaux, A.; Ducroux, L.; En’yo, H.; Ferretti, A.; Floris, M.; Foerster, A.; Force, P.; Guettet, N.; Guichard, A.; Gulkanian, H.; Heuser, J. M.; Keil, M.; Kluberg, L.; Lozano, J.; Lourenço, C.; Manso, F.; Masoni, A.; Martins, P.; Neves, A.; Ohnìshì, H.; Oppedisano, C.; Parracho, P. G. Ferreira; Pillot, P.; Puddu, G.; Radermacher, E.; Ramalhete, P.; Rosinský, P.; Scomparin, E.; Seixas, J.; Serci, S.; Sonderegger, P.; Specht, H. J.; Tieulent, R.; Usai, G. L.; Veenhof, R.; Wöhri, H. K.

doi:10.1140/epjc/s10052-006-0111-8

Cited by 9 publications

(12 citation statements)

References 15 publications

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“…Fig. 4 shows a set of mass spectra for some selected slices in p T to illustrate the evolution from low to high p T (a p T -integrated mass spectrum over the whole mass region is contained in [11]). The spectra are normalized to dN ch /dη in absolute terms, using the same procedure as described in detail for the φ in [25] and relating N part ≃ dN ch /dη at η=2.9 as measured to within 10% by the Si pixel telescope.…”

Section: Acceptance-corrected Mass and P T Spectramentioning

confidence: 99%

“…Their slopes are, however, quite different (see below). The central NA60 results in the IMR region [11] are shown in Fig. 6.…”

Section: Acceptance-corrected Mass and P T Spectramentioning

confidence: 99%

“…A big step forward in technology, leading to completely new standards of the data quality in this field, has recently been achieved by NA60, a third-generation experiment built specifically to follow up the open issues addressed above [11]. Initial results on mass and transverse momentum spectra of the excess dimuons have already been published [11,12,13], supplemented by recent results on acceptance-corrected mass spectra and polarization [14]. This paper takes a broader view on the results, discussing in some detail the observed M -p T correlations, the connection to hadron-parton duality, and the present status of theoretical modeling.…”

Section: Introductionmentioning

confidence: 99%

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NA60 results on thermal dimuons

Arnaldi¹,

Banicz²,

Borer³

et al. 2009

Eur. Phys. J. C

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133

152

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The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158 A GeV In-In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2 < M < 2.6 GeV. The mass spectrum for M < 1 GeV is consistent with a dominant contribution from π + π − → ρ → μ + μ − annihilation. The associated ρ spectral function shows a strong broadening, but essentially no shift in mass. For M > 1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell-Yan pairs. The slope parameter T eff associated with the transverse momentum spectra rises with mass up to the ρ, followed by a sudden decline above. The rise for M < 1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M > 1 GeV and its relation to parton-hadron duality is discussed in detail, suggesting a dominantly partonic emission source in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated empirical evidence, including also a Plancklike shape of the mass spectra at low p T and the lack of a e-mail: sanja.damjanovic@cern.ch polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude with first results on ω in-medium effects.PACS 25.75.-q · 12.38.Mh · 13.85.Qk

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Section: Acceptance-corrected Mass and P T Spectramentioning

confidence: 99%

“…Their slopes are, however, quite different (see below). The central NA60 results in the IMR region [11] are shown in Fig. 6.…”

Section: Acceptance-corrected Mass and P T Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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NA60 results on thermal dimuons

Arnaldi¹,

Banicz²,

Borer³

et al. 2009

Eur. Phys. J. C

Self Cite

133

152

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“…In this context, concerning the in-medium behavior of vector mesons, measurements of dileptons produced in relativistic heavyion collisions have attracted great interest over the past decades (see, e.g., Ref. [3]). Dileptons as well as photons are excellent probes carrying information about vector meson spectral functions at the high temperatures and densities reached in the collision zone.…”

Section: Introductionmentioning

confidence: 99%

Vector mesons at finite temperature and QCD sum rules

2010

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Finite energy sum rules for vector and axial-vector currents are derived in a thermal medium to provide constraints for the spectral behavior of rho and a1 mesons at nonvanishing temperature and hence to study the tendency toward chiral symmetry restoration. The parity-mixing ansatz for the rho and a1 spectra, including finite widths, is investigated as a function of temperature. Characteristic differences between vector and axial-vector channels are discussed with regard to the implementation of the chiral-symmetry-breaking scale, 4pi times the pion decay constant, in the sum rule approach.Comment: 9 pages, 6 figure

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“…Results for dimuons, already presented in [7], are briefly summarized in the following. The dimuon sample consist of 440000 signal muon pairs.…”

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confidence: 99%

NA60 results on ϕ production in the hadronic and leptonic channels in In-In collisions at 158 GeV

Falco

2009

Nuclear Physics A

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The NA60 experiment at the CERN SPS studied φ meson production in In-In collisions at 158 A GeV via muon and kaon decay channels. Results in the hadronic channel are presented for the first time. These are discussed in the framework of the so-called φ puzzle through the comparison with the previous NA60 measurements in the muon channel. The yield and inverse m T slopes observed in the two channels are compatible within errors, showing that the large discrepancies seen in Pb-Pb collisions between NA50 (muon pairs) and NA49 (kaon pairs) are not seen in the NA60 In-In data.Strangeness enhancement was proposed already in 1982 as a signature of the occurrence of the quark gluon plasma phase [1]. Due to its ss valence quark content, the φ meson is a particularly valuable probe for the measurement of strangeness production.φ production measurements were performed at the CERN SPS by the NA49, NA50 and CERES experiments in lead induced collisions at 158 A·GeV. Discrepancies were observed in the measurements performed by NA50 [2] in the muon channel and by NA49 [3] in the kaon channel, both in Pb-Pb collisions. The φ multiplicity measured by NA50 is much higher than the one obtained by NA49. Concerning the transverse mass distributions, NA50 finds an inverse slope of about 230 MeV, almost independent of centrality, while NA49 measures values increasing with the number of participants N part from ∼250 MeV to ∼300 MeV.The origin of this discrepancy, known as the φ puzzle, has long been discussed. It was suggested that kaons may suffer rescattering and absorption in the medium, resulting in a depletion of kaon pairs, especially at low p T , that leads to a reduced yield and a hardening of the p T distribution in the hadronic channel. In this frame, the yield in lepton pairs is expected to exceed the one in kaon pairs by about 50% [4].Recent results by CERES [5] on φ production in Pb-Au collisions via the K + K − and e + e − decay channels confirm the NA49 results, and thus suggest that there is no φ puzzle. However, the results in dielectrons, being affected by large statistical errors, are not conclusive. The NA60 experiment at the CERN SPS studied φ meson production in In-In collisions both in muon and kaon pairs. Details of the apparatus are reported in [6].The sample used for the results presented in this paper was collected with a 158 A·GeV In beam impinging on a segmented In target, composed of 7 subtargets of 17% total interaction probability placed in vacuum. 230 million triggers, mainly dimuons, were acquired. In order to avoid events with reinteractions of nuclear fragments in the subsequent targets, only events with one vertex in the target region were selected.

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φ meson production in NA60

Cited by 9 publications

References 15 publications

NA60 results on thermal dimuons

NA60 results on thermal dimuons

Vector mesons at finite temperature and QCD sum rules

NA60 results on ϕ production in the hadronic and leptonic channels in In-In collisions at 158 GeV

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