Nuclear dependence of light neutral meson production in p–A collisions at 400 GeV with NA60

R. Arnaldi; K. Banicz; K. Borer; J. Castor; B. Chaurand; W. Chen; C. Cicalò; A. Colla; P. Cortese; S. Damjanovic; A. David; A. De Falco; A. Devaux; L. Ducroux; H. En’yo; J. Fargeix; A. Ferretti; M. Floris; A. Förster; P. Force; N. Guettet; A. Guichard; H. Gulkanian; J. M. Heuser; P. Jarron; M. Keil; L. Kluberg; Z. Li; C. Lourenço; J. Lozano; F. Manso; P. Martins; A. Masoni; A. Neves; H. Ohnishi; C. Oppedisano; P. Parracho; P. Pillot; T. Poghosyan; G. Puddu; E. Radermacher; P. Ramalhete; P. Rosinsky; E. Scomparin; J. Seixas; S. Serci; R. Shahoyan; P. Sonderegger; H. J. Specht; R. Tieulent; A. Uras; G. Usai; R. Veenhof; H. K. Wöhri

doi:10.1140/epjc/s10052-019-6848-7

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2019) 79: 443
https://doi.org/10.1140/epjc/s10052-019-6848-7

Regular Article - Experimental Physics

Nuclear dependence of light neutral meson production in p–A collisions at 400 GeV with NA60

R. Arnaldi¹, K. Banicz²^,3, K. Borer⁴, J. Castor⁵, B. Chaurand⁶, W. Chen⁷, C. Cicalò⁸, A. Colla¹^,9, P. Cortese⁹^,10, S. Damjanovic²^,3, A. David²^,11, A. De Falco⁸^,12, A. Devaux⁵, L. Ducroux¹³, H. En’yo⁴, J. Fargeix⁵, A. Ferretti¹^,9, M. Floris⁸^,12, A. Förster², P. Force⁵, N. Guettet²^,5, A. Guichard¹³, H. Gulkanian¹⁵, J. M. Heuser¹⁴, P. Jarron², M. Keil²^,11, L. Kluberg⁶, Z. Li⁷, C. Lourenço², J. Lozano¹¹, F. Manso⁵, P. Martins²^,11, A. Masoni⁸, A. Neves¹¹, H. Ohnishi¹⁴, C. Oppedisano¹, P. Parracho²^,11, P. Pillot¹³, T. Poghosyan¹⁵, G. Puddu¹², E. Radermacher², P. Ramalhete²^,11, P. Rosinsky², E. Scomparin¹, J. Seixas¹¹^,16^,17, S. Serci⁸^,12, R. Shahoyan²^,11, P. Sonderegger¹¹, H. J. Specht³, R. Tieulent¹³, A. Uras⁸^,12^,13^*, G. Usai⁸^,12^**, R. Veenhof¹¹, H. K. Wöhri²^,11^,12 and NA60 Collaboration

¹ INFN, Torino, Italy
² CERN, Geneva, Switzerland
³ Physikalisches Institut der Universität Heidelberg, Heidelberg, Germany
⁴ University of Bern, Bern, Switzerland
⁵ LPC, Université Clermont Auvergne and CNRS-IN2P3, Clermont-Ferrand, France
⁶ LLR, Ecole Polytechnique and CNRS-IN2P3, Palaiseau, France
⁷ BNL, Upton, NY, USA
⁸ INFN, Cagliari, Italy
⁹ Università di Torino, Torino, Italy
¹⁰ Università del Piemonte Orientale, Alessandria, Italy
¹¹ Instituto Superior Tecnico, Dep. Fisica, Lisbon, Portugal
¹² Università di Cagliari, Cagliari, Italy
¹³ IPN-Lyon, Univ. Claude Bernard Lyon-I and CNRS-IN2P3, Lyon, France
¹⁴ RIKEN, Wako, Saitama, Japan
¹⁵ YerPhI, Yerevan, Armenia
¹⁶ Center for Physics and Engineering of Advanced Materials (CeFEMA), Lisbon, Portugal
¹⁷ Laboratorio de Intrumentação e Fisica experimental de Particulas (LIP), Lisbon, Portugal

^* e-mail: antonio.uras@cern.ch
^** e-mail: gianluca.usai@ca.infn.it

Received: 26 September 2018
Accepted: 1 April 2019
Published online: 25 May 2019

Abstract

The NA60 experiment has studied low-mass muon pair production in proton–nucleus collisions with a system of Be, Cu, In, W, Pb and U targets, using a 400 GeV proton beam at the CERN SPS. The transverse momentum spectra of the $\rho /\omega$ and $\phi$ mesons are measured in the full $p_{\mathrm {T}}$ range accessible, from $p_{\mathrm {T}}= 0$ up to $2 \, {\hbox {GeV/c}}$ . The nuclear dependence of the production cross sections of the $\eta$ , $\omega$ and $\phi$ mesons has been found to be consistent with the power law $\sigma _{\mathrm {pA}} \propto {\mathrm {A}}^\alpha$ , with the $\alpha$ parameter increasing as a function of $p_{\mathrm {T}}$ for all the particles, and an approximate hierarchy $\alpha _\eta \approx \alpha _\phi > \alpha _\omega$ . The cross section ratios $\sigma _\eta /\sigma _\omega$ , $\sigma _\rho /\sigma _\omega$ and $\sigma _\phi /\sigma _\omega$ have been studied as a function of the size A of the production target, and an increase of the $\eta$ and $\phi$ yields relative to the $\omega$ is observed from p–Be to p–U collisions.