2039813 SzGeCERN 20220810143553.0 oai:cds.cern.ch:2039813 cerncds:FULLTEXT cerncds:CERN:FULLTEXT cerncds:CERN DOI 10.1103/PhysRevD.94.032007 arXiv oai:arXiv.org:1507.08764 Inspire 1385877 arXiv arXiv:1507.08764 hep-ex CERN-PH-EP-2015-201 eng CERN Library PH-EP-2015-201 CERN-PH-EP-2015-201 CERN-PH-EP-DRAFT-LHCf-2015-002 Adriani, O. INFN, Florence Florence U. INFN Section of Florence , Italy and University of Florence , Italy Measurements of longitudinal and transverse momentum distributions for neutral pions in the forward-rapidity region with the LHCf detector 2016-08-22 Geneva CERN 31 Jul 2015 38 p arXiv 47 pages, 23 figures, 59 tables, accepted in PRD takashi.sako@cern.ch takashi.sako@cern.ch cds-ph-ep-publications-referee [CERN] The transverse and longitudinal momentum distributions for inclusive neutral pions in the very forward rapidity region have been measured with the Large Hadron Collider forward detector in proton-proton collisions at $\sqrt{s}=$ 2.76 and 7 TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of $\sqrt{s_\text{NN}}=$ 5.02 TeV at the LHC. Such momentum distributions in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. A sizable suppression of the production of neutral pions, after taking into account ultraperipheral collisions, is found in the transverse and longitudinal momentum distributions obtained in proton-lead collisions. This leads to a strong nuclear modification factor value of about 0.1-0.3. The experimental measurements presented in this paper provide a benchmark for the hadronic interaction Monte Carlo simulations codes that are used for the simulation of air showers. HEPDATA CERN-LHC. The differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward rapidity region have been measured at the Large Hadron Collider (LHC) with the Large Hadron Collider forward detector (LHCf) in proton-proton collisions at $\sqrt{s}=$ 2.76 and 7 TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of $\sqrt{s_\text{NN}}=$ 5.02 TeV. Such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. Comparing proton-proton with proton-lead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultra-peripheral proton-lead collisions. This suppression corresponds to the nuclear modification factor value of about 0.1-0.3. The experimental measurements presented in this paper provide a benchmark for the hadronic interaction Monte Carlo simulation codes that are used for the simulation of cosmic ray air showers. APS The differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward-rapidity region have been measured at the LHC with the LHC forward detector in proton-proton collisions at s=2.76 and 7 TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of sNN=5.02  TeV. Such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. Comparing proton-proton with proton-lead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultraperipheral proton-lead collisions. This suppression corresponds to the nuclear modification factor value of about 0.1–0.3. The experimental measurements presented in this paper provide a benchmark for the hadronic interaction Monte Carlo simulation codes that are used for the simulation of cosmic ray air showers. arXiv The differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward rapidity region have been measured at the Large Hadron Collider (LHC) with the Large Hadron Collider forward detector (LHCf) in proton-proton collisions at $\sqrt{s}=$ 2.76 and 7 TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of $\sqrt{s_\text{NN}}=$ 5.02 TeV. Such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. Comparing proton-proton with proton-lead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultra-peripheral proton-lead collisions. This suppression corresponds to the nuclear modification factor value of about 0.1-0.3. The experimental measurements presented in this paper provide a benchmark for the hadronic interaction Monte Carlo simulation codes that are used for the simulation of cosmic ray air showers. preprint CC-BY-4.0 publication CC-BY-3.0 preprint CERN 2015 publication CERN 2015 CERN EDS LANL EDS CERN-PH-EP arXiv Particle Physics - Experiment CERN forward physics CERN minimum bias CERN experimental results CERN ARTICLE LHCf_Papers CERN LHC LHCf LANL EDS hep-ex Berti, E. INFN, Florence Florence U. INFN Section of Florence , Italy and University of Florence , Italy Bonechi, L. INFN, Florence INFN Section of Florence , Italy Bongi, M. INFN, Florence Florence U. INFN Section of Florence , Italy and University of Florence , Italy D'Alessandro, R. INFN, Florence Florence U. INFN Section of Florence , Italy and University of Florence , Italy Del Prete, M. INFN, Florence Florence U. INFN Section of Florence , Italy and University of Florence , Italy Haguenauer, M. Ec. Polytech., Palaiseau (main) Ecole-Polytechnique , Palaiseau, France Itow, Y. Nagoya U., Solar-Terrestrial Environ. Lab. KMI, Nagoya Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan and Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University , Nagoya, Japan Iwata, T. Waseda U., RISE Kasahara, K. Waseda U., RISE RISE, Waseda University , Japan Kawade, K. Nagoya U., Solar-Terrestrial Environ. Lab. Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan Makino, Y. Nagoya U., Solar-Terrestrial Environ. Lab. Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan Masuda, K. Nagoya U., Solar-Terrestrial Environ. Lab. Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan Matsubayashi, E. Nagoya U., Solar-Terrestrial Environ. Lab. Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan Menjo, H. Nagoya U. Graduate school of Science, Nagoya University , Japan Mitsuka, G. gaku.mitsuka@riken.jp Florence U. University of Florence , Italy Muraki, Y. Nagoya U., Solar-Terrestrial Environ. Lab. Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan Papini, P. INFN, Florence INFN Section of Florence , Italy Perrot, A.L. CERN CERN , Switzerland Ricciarini, S. INFN, Florence IFAC, Florence INFN Section of Florence , Italy and IFAC-CNR , Italy Sako, T. Nagoya U., Solar-Terrestrial Environ. Lab. KMI, Nagoya Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan and Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University , Nagoya, Japan Sakurai, N. KMI, Nagoya Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University , Nagoya, Japan Suzuki, T. Waseda U., RISE RISE, Waseda University , Japan Tamura, T. Kanagawa U. Kanagawa University , Japan Tiberio, A. INFN, Florence Florence U. INFN Section of Florence , Italy and University of Florence , Italy Torii, S. Waseda U., RISE RISE, Waseda University , Japan Tricomi, A. INFN, Catania Catania U. INFN Section of Catania , Italy and University of Catania , Italy Turner, W.C. LBL, Berkeley LBNL , Berkeley, California, USA Ueno, M. KMI, Nagoya Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan Zhou, Q.D. Nagoya U., Solar-Terrestrial Environ. Lab. Institute for Space-Earth Environmental Research, Nagoya University , Nagoya, Japan PH LHCf Collaboration 032007 Phys. Rev. D 94, 032007 (2016) Phys. Rev. D 94 2016 https://rivet.hepforge.org/analyses/LHCF_2016_I1385877 Rivet analyses reference 1154861 2256989 http://cds.cern.ch/record/2039813/files/arXiv:1507.08764.pdf 1154858 34439 http://cds.cern.ch/record/2039813/files/dndy.png 00019 (color online). The $\pizero$ yield in each rapidity interval as a function of rapidity loss $\deltay = \ybeam-y$. Open red circles and filled black circles indicate LHCf data in $\pp$ collisions at $\sqs=2.76$ and $\tev{7}$, respectively. The results of the UA7 experiment (open magenta squares) at Sp$\bar{\text{p}}$S ($p+\bar{p}$ collisions at $\sqs=\gev{630}$) and the predictions by \textsc{dpmjet} (thick red line) and \textsc{qgsjet} (thin blue line) are added for reference. 1154859 7994 http://cds.cern.ch/record/2039813/files/energy_2TeV.png 00011 (color online). LHCf $\pz$ distributions (filled circles) in $\pp$ collisions at $\sqs=\tev{2.76}$. Error bars indicate the total statistical and systematic uncertainties. The predictions of hadronic interaction models are shown for comparison: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), \textsc{sibyll} (dotted green line), \textsc{epos} (dashed-dotted magenta line), and \textsc{pythia} (dashed-double-dotted brown line). 1154860 21567 http://cds.cern.ch/record/2039813/files/pt_pPb.png 00013 (color online). LHCf $\pt$ distributions (filled circles) in $\pPb$ collisions at $\snn=\tev{5.02}$. Error bars indicate the total statistical and systematic uncertainties. The predictions of hadronic interaction models are shown for comparison: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), and \textsc{epos} (dashed-dotted magenta line). 1154862 46825 http://cds.cern.ch/record/2039813/files/pt_scale.png 00018 (color online). Average $\pt$ as a function of rapidity loss $\deltay = \ybeam-y$. Open red circles and filled black circles indicate LHCf data in $\pp$ collisions at $\sqs=2.76$ and $\tev{7}$, respectively. The results of the UA7 experiment (open magenta box) at Sp$\bar{\text{p}}$S ($p+\bar{p}$ collisions at $\sqs=\gev{630}$) and the predictions from \textsc{dpmjet} (thick lines) and \textsc{qgsjet} (thin lines) are added for reference. 1154863 26096 http://cds.cern.ch/record/2039813/files/xf.png 00021 (color online). The $\pizero$ yield in each $\pt$ range as a function of $\xf$. Left: the distributions for $0.0<\pt<\gev{0.2}$. Right: the distributions for $0.2<\pt<\gev{0.4}$. Open red circles and filled black circles indicate LHCf data in $\pp$ collisions at $\sqs=2.76$ and $\tev{7}$, respectively. 1154864 79543 http://cds.cern.ch/record/2039813/files/acceptance.png 00004 (color online). The acceptance map of $\pizero$ detection by the LHCf detectors in $\pz$--$\pt$ phase space: Arm1 Type-I (left top), Arm1 Type-II (right top), Arm2 Type-I (left bottom), and Arm2 Type-II (right bottom). The fiducial area cuts and energy threshold ($E_{\text{photon}}>\gev{100}$) are taken into account. Dashed curves indicate lines of constant rapidity $\pizero$s, $y$ = 8.8, 9.0, and 10.0 reading from top to bottom. 1154865 22250 http://cds.cern.ch/record/2039813/files/pt_7TeV.png 00005 (color online). LHCf $\pt$ distributions (filled circles) in $\pp$ collisions at $\sqs=\tev{7}$. Error bars indicate the total statistical and systematic uncertainties. The predictions of hadronic interaction models are shown for comparison: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), \textsc{sibyll} (dotted green line), \textsc{epos} (dashed-dotted magenta line), and \textsc{pythia} (dashed-double-dotted brown line). 1154866 29951 http://cds.cern.ch/record/2039813/files/pt_fit.png 00017 (color online). LHCf $\pt$ distributions (filled black circles), the best-fit Gaussian distributions (dotted red curve), and the best-fit Hagedorn functions (dashed blue curve). Left: the data for $\pp$ collisions at $\sqs=\tev{7}$. Right: the data for $\pPb$ collisions at $\snn=\tev{5.02}$. 1154867 16051 http://cds.cern.ch/record/2039813/files/nmf.png 00023 (color online). The nuclear modification factor for $\pizero$s. Filled circles indicate the factors obtained from LHCf data. Error bars indicate the total uncertainties incorporating both statistical and systematic uncertainties. Other lines are the predictions from hadronic interaction models: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), and \textsc{epos} (dashed-dotted magenta line). 1154868 16188 http://cds.cern.ch/record/2039813/files/energy_pPb.png 00015 (color online). LHCf $\pz$ distributions (filled circles) in $\pPb$ collisions at $\snn=\tev{5.02}$. Error bars indicate the total statistical and systematic uncertainties. The predictions of hadronic interaction models are shown for comparison: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), and \textsc{epos} (dashed-dotted magenta line). 1154869 32951 http://cds.cern.ch/record/2039813/files/mass.png 00002 (color online). Reconstructed invariant mass distributions in $\pp$ collisions at $\sqs=\tev{7}$. Left: Type-II $\pizero$ events in the Arm2 small calorimeter. Right: Type-II $\pizero$ events in the Arm2 large calorimeter. The solid curves show the best-fit composite physics model to the invariant mass distributions. 1154870 16948 http://cds.cern.ch/record/2039813/files/energy_7TeV.png 00007 (color online). LHCf $\pz$ distributions (filled circles) in $\pp$ collisions at $\sqs=\tev{7}$. Error bars indicate the total statistical and systematic uncertainties. The predictions of hadronic interaction models are shown for comparison: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), \textsc{sibyll} (dotted green line), \textsc{epos} (dashed-dotted magenta line), and \textsc{pythia} (dashed-double-dotted brown line). 1154871 13175 http://cds.cern.ch/record/2039813/files/pt_2TeV.png 00009 (color online). LHCf $\pt$ distributions (filled circles) in $\pp$ collisions at $\sqs=\tev{2.76}$. Error bars indicate the total statistical and systematic uncertainties. The predictions of hadronic interaction models are shown for comparison: \textsc{dpmjet} (solid red line), \textsc{qgsjet} (dashed blue line), \textsc{sibyll} (dotted green line), \textsc{epos} (dashed-dotted magenta line), and \textsc{pythia} (dashed-double-dotted brown line). 1154872 8973 http://cds.cern.ch/record/2039813/files/type1.png 00000 (color online). Observation of $\pizero$ decay by a LHCf detector. Left: Type-I $\pizero$ event having one photon entering each calorimeter. Right: Type-II $\pizero$ event having two photons entering one calorimeter, here entering the small calorimeter. 1154873 13547 http://cds.cern.ch/record/2039813/files/xf2.png 00020 (color online). The $\pizero$ yield at $0.0<\pt<\gev{0.4}$ as a function of $\xf$. Open red circles and filled black circles indicate LHCf data in $\pp$ collisions at $\sqs=2.76$ and $\tev{7}$, respectively. 1154874 11657 http://cds.cern.ch/record/2039813/files/xf_expo.png 00022 (color online). The best-fit leading exponent of (1-$\xf$) as a function of $\pt$. Open red circles and filled black circles indicate LHCf data in $\pp$ collisions at $\sqs=2.76$ and $\tev{7}$, respectively. Filled blue triangles indicate LHCf data in $\pPb$ collisions at $\snn=\tev{5.02}$. 1154875 8023 http://cds.cern.ch/record/2039813/files/type2.png 00001 (color online). Observation of $\pizero$ decay by a LHCf detector. Left: Type-I $\pizero$ event having one photon entering each calorimeter. Right: Type-II $\pizero$ event having two photons entering one calorimeter, here entering the small calorimeter. 1235121 8131 http://cds.cern.ch/record/2039813/files/energy_2TeV_ratio.png 00012 (color online). Ratios of LHCf $\pz$ distributions to the $\pz$ distributions predicted by hadronic interaction models in $\pp$ collisions at $\sqs=\tev{2.76}$ are shown by solid red line (\textsc{dpmjet}), dashed blue line (\textsc{qgsjet}), dotted green line (\textsc{sibyll}), dashed-dotted magenta line (\textsc{epos}), and dashed-double-dotted brown line (\textsc{pythia}). Shaded areas indicate the range of total uncertainties of the $\pz$ distributions. 1235122 16148 http://cds.cern.ch/record/2039813/files/energy_7TeV_ratio.png 00008 (color online). Ratios of LHCf $\pz$ distributions to the $\pz$ distributions predicted by hadronic interaction models in $\pp$ collisions at $\sqs=\tev{7}$ are shown by solid red line (\textsc{dpmjet}), dashed blue line (\textsc{qgsjet}), dotted green line (\textsc{sibyll}), dashed-dotted magenta line (\textsc{epos}), and dashed-double-dotted brown line (\textsc{pythia}). Shaded areas indicate the range of total uncertainties of the LHCf $\pz$ distributions. 1235123 25534 http://cds.cern.ch/record/2039813/files/pt_7TeV_ratio.png 00006 (color online). Ratios of LHCf $\pt$ distributions to the $\pt$ distributions predicted by hadronic interaction models in $\pp$ collisions at $\sqs=\tev{7}$ are shown by solid red line (\textsc{dpmjet}), dashed blue line (\textsc{qgsjet}), dotted green line (\textsc{sibyll}), dashed-dotted magenta line (\textsc{epos}), and dashed-double-dotted brown line (\textsc{pythia}). Shaded areas indicate the range of total uncertainties of the LHCf $\pt$ distributions. 1235124 14158 http://cds.cern.ch/record/2039813/files/pt_2TeV_ratio.png 00010 (color online). Ratios of LHCf $\pt$ distributions to the $\pt$ distributions predicted by hadronic interaction models in $\pp$ collisions at $\sqs=\tev{2.76}$ are shown by solid red line (\textsc{dpmjet}), dashed blue line (\textsc{qgsjet}), dotted green line (\textsc{sibyll}), dashed-dotted magenta line (\textsc{epos}), and dashed-double-dotted brown line (\textsc{pythia}). Shaded areas indicate the range of total uncertainties of the $\pt$ spectra. 1235125 5592 http://cds.cern.ch/record/2039813/files/multipi0.png 00003 (color online). Diagrams of all multi-hit events that are rejected. Panels (a) and (b) show the multi-hit Type-I $\pizero$ events and panels (c) and (d) show the multi-hit Type-II $\pizero$ events. Red and green arrows indicate a background particle not originating in a $\pizero$ decay and two photons originating in a $\pizero$ decay, respectively. 1235126 20891 http://cds.cern.ch/record/2039813/files/pt_pPb_ratio.png 00014 (color online). Ratios of LHCf $\pt$ distributions to the $\pt$ distributions predicted by hadronic interaction models in $\pPb$ collisions at $\snn=\tev{5.02}$ are shown by solid red line (\textsc{dpmjet}), dashed blue line (\textsc{qgsjet}), and dashed-dotted magenta line (\textsc{epos}). Shaded areas indicate the range of total uncertainties of the $\pt$ distributions. 1235127 15184 http://cds.cern.ch/record/2039813/files/energy_pPb_ratio.png 00016 (color online). Ratios of LHCf $\pz$ distributions to the $\pz$ distributions predicted by hadronic interaction models in $\pPb$ collisions at $\snn=\tev{5.02}$ are shown by solid red line (\textsc{dpmjet}), dashed blue line (\textsc{qgsjet}), and dashed-dotted magenta line (\textsc{epos}). Shaded areas indicate the range of total uncertainties of the $\pt$ distributions. 1240820 2216176 http://cds.cern.ch/record/2039813/files/PhysRevD.94.032007.pdf APS 1463943 2216176 http://cds.cern.ch/record/2039813/files/10.1103_PhysRevD.94.032007.pdf Fulltext 1240820 3062137 http://cds.cern.ch/record/2039813/files/PhysRevD.94.032007.pdf?subformat=pdfa pdfa APS Open Access article takashi.sako@cern.ch Approval requested for number CERN-PH-EP-2015-201 CERN-PH-EP-2015-201 EPPHAPP 2015-07-28 19:59:24 2015-08-04 19:59:24 takashi.sako@cern.ch waiting Document approved CERN-PH-EP-2015-201 EPPHAPP 2015-07-30 11:15:14 roger.forty@cern.ch approved n 201531 13 LHCf_Papers ARTICLE 2038550