First measurement of the Q spectral function in nuclear collisions

R. Arnaldi; R. Averbeck; K. Banicz; J. Castor; B. Chaurand; C. Cicalo; A. Colla; P. Cortese; S. Damjanovic; A. David; A. De Falco; A. Devaux; A. Drees; L. Ducroux; H. En'Yo; A. Ferretti; M. Floris; A. Foerster; P. Force; N. Guettet; A. Guichard; H. Gulkanian; J. Heuser; M. Keil; L. Kluberg; J. Lozano; C. Lourenço; F. Manso; A. Masoni; P. Martins; A. Neves; H. Ohnishi; C. Oppedisano; P. Parracho; P. Pillot; G. Puddu; E. Radermacher; P. Ramalhete; P. Rosinsky; E. Scomparin; J. Seixas; S. Serci; R. Shahoyan; P. Sonderegger; H. J. Specht; R. Tieulent; G. Usai; R. Veenhof; H. K. Wöhri

doi:10.1140/epjc/s10052-006-0060-2

First measurement of the Q spectral function in nuclear collisions

R. Arnaldi, R. Averbeck, K. Banicz, J. Castor, B. Chaurand, C. Cicalo, A. Colla, P. Cortese, S. Damjanovic, A. David, A. De Falco, A. Devaux, A. Drees, L. Ducroux, H. En'Yo, A. Ferretti, M. Floris, A. Foerster, P. Force, N. GuettetA. Guichard, H. Gulkanian, J. Heuser, M. Keil, L. Kluberg, J. Lozano, C. Lourenço, F. Manso, A. Masoni, P. Martins, A. Neves, H. Ohnishi, C. Oppedisano, P. Parracho, P. Pillot, G. Puddu, E. Radermacher, P. Ramalhete, P. Rosinsky, E. Scomparin, J. Seixas, S. Serci, R. Shahoyan, P. Sonderegger, H. J. Specht, R. Tieulent, G. Usai, R. Veenhof, H. K. Wöhri

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Abstract

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A∈GeV In-In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π⁺π ^-→ →μ⁺μ^- annihilation. The associated Q spectral function exhibits considerable broadening, but essentially no shift in mass. The p_T-differential mass spectra show the excess to be much stronger at low p_T than at high p_T. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.

Original language	English
Pages (from-to)	235-241
Number of pages	7
Journal	European Physical Journal C
Volume	49
Issue number	1
DOIs	https://doi.org/10.1140/epjc/s10052-006-0060-2
Publication status	Published - Jan 2007
Externally published	Yes

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10.1140/epjc/s10052-006-0060-2

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Arnaldi, R., Averbeck, R., Banicz, K., Castor, J., Chaurand, B., Cicalo, C., Colla, A., Cortese, P., Damjanovic, S., David, A., De Falco, A., Devaux, A., Drees, A., Ducroux, L., En'Yo, H., Ferretti, A., Floris, M., Foerster, A., Force, P., ... Wöhri, H. K. (2007). First measurement of the Q spectral function in nuclear collisions. European Physical Journal C, 49(1), 235-241. https://doi.org/10.1140/epjc/s10052-006-0060-2

@article{bdec60a420974bcd81797ff6a08ddc6e,

title = "First measurement of the Q spectral function in nuclear collisions",

abstract = "The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A∈GeV In-In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π+π -→ →μ+μ- annihilation. The associated Q spectral function exhibits considerable broadening, but essentially no shift in mass. The pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.",

author = "R. Arnaldi and R. Averbeck and K. Banicz and J. Castor and B. Chaurand and C. Cicalo and A. Colla and P. Cortese and S. Damjanovic and A. David and {De Falco}, A. and A. Devaux and A. Drees and L. Ducroux and H. En'Yo and A. Ferretti and M. Floris and A. Foerster and P. Force and N. Guettet and A. Guichard and H. Gulkanian and J. Heuser and M. Keil and L. Kluberg and J. Lozano and C. Louren{\c c}o and F. Manso and A. Masoni and P. Martins and A. Neves and H. Ohnishi and C. Oppedisano and P. Parracho and P. Pillot and G. Puddu and E. Radermacher and P. Ramalhete and P. Rosinsky and E. Scomparin and J. Seixas and S. Serci and R. Shahoyan and P. Sonderegger and Specht, {H. J.} and R. Tieulent and G. Usai and R. Veenhof and W{\"o}hri, {H. K.}",

year = "2007",

month = jan,

doi = "10.1140/epjc/s10052-006-0060-2",

language = "English",

volume = "49",

pages = "235--241",

journal = "European Physical Journal C",

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Arnaldi, R, Averbeck, R, Banicz, K, Castor, J, Chaurand, B, Cicalo, C, Colla, A, Cortese, P, Damjanovic, S, David, A, De Falco, A, Devaux, A, Drees, A, Ducroux, L, En'Yo, H, Ferretti, A, Floris, M, Foerster, A, Force, P, Guettet, N, Guichard, A, Gulkanian, H, Heuser, J, Keil, M, Kluberg, L, Lozano, J, Lourenço, C, Manso, F, Masoni, A, Martins, P, Neves, A, Ohnishi, H, Oppedisano, C, Parracho, P, Pillot, P, Puddu, G, Radermacher, E, Ramalhete, P, Rosinsky, P, Scomparin, E, Seixas, J, Serci, S, Shahoyan, R, Sonderegger, P, Specht, HJ, Tieulent, R, Usai, G, Veenhof, R & Wöhri, HK 2007, 'First measurement of the Q spectral function in nuclear collisions', European Physical Journal C, vol. 49, no. 1, pp. 235-241. https://doi.org/10.1140/epjc/s10052-006-0060-2

TY - JOUR

T1 - First measurement of the Q spectral function in nuclear collisions

AU - Arnaldi, R.

AU - Averbeck, R.

AU - Banicz, K.

AU - Castor, J.

AU - Chaurand, B.

AU - Cicalo, C.

AU - Colla, A.

AU - Cortese, P.

AU - Damjanovic, S.

AU - David, A.

AU - De Falco, A.

AU - Devaux, A.

AU - Drees, A.

AU - Ducroux, L.

AU - En'Yo, H.

AU - Ferretti, A.

AU - Floris, M.

AU - Foerster, A.

AU - Force, P.

AU - Guettet, N.

AU - Guichard, A.

AU - Gulkanian, H.

AU - Heuser, J.

AU - Keil, M.

AU - Kluberg, L.

AU - Lozano, J.

AU - Lourenço, C.

AU - Manso, F.

AU - Masoni, A.

AU - Martins, P.

AU - Neves, A.

AU - Ohnishi, H.

AU - Oppedisano, C.

AU - Parracho, P.

AU - Pillot, P.

AU - Puddu, G.

AU - Radermacher, E.

AU - Ramalhete, P.

AU - Rosinsky, P.

AU - Scomparin, E.

AU - Seixas, J.

AU - Serci, S.

AU - Shahoyan, R.

AU - Sonderegger, P.

AU - Specht, H. J.

AU - Tieulent, R.

AU - Usai, G.

AU - Veenhof, R.

AU - Wöhri, H. K.

PY - 2007/1

Y1 - 2007/1

N2 - The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A∈GeV In-In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π+π -→ →μ+μ- annihilation. The associated Q spectral function exhibits considerable broadening, but essentially no shift in mass. The pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.

AB - The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A∈GeV In-In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π+π -→ →μ+μ- annihilation. The associated Q spectral function exhibits considerable broadening, but essentially no shift in mass. The pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.

UR - http://www.scopus.com/inward/record.url?scp=33846428120&partnerID=8YFLogxK

U2 - 10.1140/epjc/s10052-006-0060-2

DO - 10.1140/epjc/s10052-006-0060-2

M3 - Article

SN - 1434-6044

VL - 49

SP - 235

EP - 241

JO - European Physical Journal C

JF - European Physical Journal C

IS - 1

ER -

First measurement of the Q spectral function in nuclear collisions

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