QGP-like effects in Small Systems with LHC Run3+ Naghmeh Mohammadi arxiv:1812.06772 (HL-LHC WG5 yellow report) � 1 01.03.2019 COST Workshop on Interplay of hard and soft QCD probes for collectivity in HIC, Lund, Sweden
Emergence of Hot and Dense QCD in Small Systems ❖ Initially a reference for the e ff ects observed in Pb-Pb collisions ❖ Observations in high multiplicity pp collisions: ❖ Azimuthal correlations of final state hadrons pp pp JHEP09(2010)091 Phys. Lett. B 765 (2017) 193 � 2 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Emergence of Hot and Dense QCD in Small Systems ❖ Initially a reference for the e ff ects observed in Pb-Pb collisions Nature Physics 13, 535–539 (2017) ❖ Observations in high multiplicity pp collisions: Κ 0s / π ❖ Azimuthal correlations of final state hadrons Λ / π ❖ Enhanced production of multi-strange hadrons Ξ / π Ω / π pp pp PbPb pPb pp JHEP09(2010)091 Phys. Lett. B 765 (2017) 193 3 � 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Emergence of Hot and Dense QCD in Small Systems ❖ Initially a reference for the e ff ects observed in Pb-Pb collisions Nature Physics 13, 535–539 (2017) ❖ Observations in high multiplicity pp collisions: Κ 0s / π ❖ Azimuthal correlations of final state hadrons ➡ Is the physical origin of collectivity the same in small and large systems? Λ / π ❖ Enhanced production of multi-strange hadrons ➡ Is there a smooth transition from pp to PbPb collisions? Ξ / π Ω / π pp pp PbPb pPb pp JHEP09(2010)091 Phys. Lett. B 765 (2017) 193 � 4 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Emergence of Hot and Dense QCD in Small Systems ❖ Initially a reference for the e ff ects observed in Pb-Pb collisions Nature Physics 13, 535–539 (2017) ❖ Observations in high multiplicity pp collisions: Κ 0s / π ❖ Azimuthal correlations of final state hadrons ➡ Is the physical origin of collectivity the same in small and large systems? Λ / π ❖ Enhanced production of multi-strange hadrons ➡ Is there a smooth transition from pp to PbPb collisions? Ξ / π ❖ Is there a unified theory to describe small and large systems simultaneously? Ω / π pp pp PbPb pPb ❖ To tackle these questions: Higher luminosity LHC for more detailed studies pp JHEP09(2010)091 Phys. Lett. B 765 (2017) 193 5 � 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Proton-proton multiplicity distribution ❖ Multiplicity distribution extrapolation based on the current ALICE and ATLAS data ❖ Extrapolated to 200 pb -1 14 TeV high multiplicity pp collisions Run 3+4 � 6 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Proton-proton multiplicity distribution ❖ Multiplicity distribution extrapolation based on the current ALICE and ATLAS data ❖ Extrapolated to 200 pb -1 14 TeV high multiplicity pp collisions ❖ Few particle systems to study the onset of collectivity Run 3+4 � 7 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Proton-proton multiplicity distribution ~65-70% PbPb ❖ Multiplicity distribution extrapolation based on the current ALICE and ATLAS data ❖ Extrapolated to 200 pb -1 14 TeV high multiplicity pp collisions ❖ 730k events in multiplicity range of 65-70% PbPb collisions ❖ Overlap between pp and PbPb allows to compare the two systems Run 3+4 � 8 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Proton-proton multiplicity distribution ~60-65% PbPb ❖ Multiplicity distribution extrapolation based on the current ALICE and ATLAS data ❖ Extrapolated to 200 pb -1 14 TeV high multiplicity pp collisions ❖ 28k events in multiplicity range of 60-65% PbPb collisions ❖ Overlap between pp and PbPb allows to compare the two systems Run 3+4 � 9 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Energy density in di ff erent collision systems Same multiplicity does not mean same energy density ❖ Energy density: ) 3 = 0.2 fm/c τ (GeV/fm ❖ An estimate for pp, pPb and Pb-Pb collisions based on ❖ IP-Glasma 2 10 Central Pb-Pb ❖ Glauber MC (for pPb and PbPb) + Bjorken estimate ε 10 ❖ Dependent on the system at fixed multiplicity ❖ It can reach large values in pp and pPb collisions, of pp p-Pb Pb-Pb the order of central Pb-Pb collisions IP Glasma 1 Glauber MC ❖ One way of calculating the energy density 0 20 40 60 80 100 dN /dy ch � 10 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
Global-event properties ❖ Shape of the multiplicity distribution ❖ Mechanisms producing very high multiplicity events not clear ❖ Mean p T increases with multiplicity ❖ Measurements exist only up to dN ch /d η ~55 ❖ HL-LHC will provide twice this value ❖ High multiplicity collisions originate from MPI within the same pp collision ❖ Understanding particle production in high energy pp collisions ❖ Number of low momentum transfer parton interactions increases linearly with multiplicity ❖ Possible saturation at large multiplicity � 11 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
<latexit sha1_base64="nJzBtlJ7Isc6eVyGzFcDp4dHlj4=">ACeHicfVFNS8NAEN3Er1q/qh69LFZREUsSC3oRC8eK1gVmho2m7dLMJuxuhPwG/5s3f4gXT27TIGrFgeU93szb3ZkJE86Udpw3y56bX1hcqixXV1bX1jdqm1v3Kk4lhTaNeSwfQ6KAMwFtzTSHx0QCiUIOD+HoepJ/eAapWCzu9DiBbkQGgvUZJdpIQe2FBpnI/azp5/gC+5yIAYcvhKeMiUM/GbLAPS7AOyngdArNoxz7svSUeIK9f+ZOr0/nE+Zlwe1utNwisCzxC1JHZXRCmqvfi+maQRCU06U6rhOorsZkZpRDnVTxUkhI7IADqGChKB6mbF4HK8b5Qe7sfSHKFxoX53ZCRSahyFpjIieqh+5ybiX7lOqvnXdNzkmoQdPpQP+VYx3iyBdxjEqjmY0MIlcz8FdMhkYRqs6uqGYL7u+VZcu81XMNvm/XLq3IcFbSDdtEhctEZukQ3qIXaiKJ3a8fas/atDxvbB/bRtNS2Ss82+hG29wlg5b1V</latexit> <latexit sha1_base64="nJzBtlJ7Isc6eVyGzFcDp4dHlj4=">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</latexit> <latexit sha1_base64="nJzBtlJ7Isc6eVyGzFcDp4dHlj4=">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</latexit> <latexit sha1_base64="nJzBtlJ7Isc6eVyGzFcDp4dHlj4=">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</latexit> Particle correlations: multi-particle cumulants pp ❖ Particle correlations: 6 − 10 × 1.5 ❖ In high multiplicity pp to compare with pPb and PbPb {4} ATLAS Internal collisions 3 c pp s =13 TeV ❖ In low multiplicity regions to investigate the onset of the 1 | |<2.5 0.3<p <3.0 GeV η collective-like e ff ects T 1.5% v {4} 3 ❖ 4 particle cumulants (c n {4}) 0.5 2.0% v {4} 3 c n { 4 } = hh e in ( φ 1 + φ 2 − φ 3 − φ 4 ) ii � 2 hh e in ( φ 1 − φ 2 ) ii 2 0 prescaled HMT unprescaled HMT ❖ Suppresses correlations from jets and dijets 0.5 − ❖ Measured in pp and pPb with Run 1 & 2 using 3 subevent method -1 Run 2, 0.9 pb 1 − ❖ c3{4} lacks statistics in pp and mostly consistent with zero -1 ❖ c3{4} negative non zero magnitude in PbPb collisions Projected, 200 pb ❖ Is c 3 {4} negative in pp collisions? 1.5 − 50 100 150 200 250 N ch Run 3+4 � 12 01.03.2019 Naghmeh Mohammadi @ COST workshop-Lund university
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