Monte Carlo study of diffraction in p-p collisions at s=13tev with the LHCf detector

Transcription

1 Monte Carlo study of diffraction in p-p collisions at s=tev with the LHCf detector Qi-Dong Zhou Nagoya University (JP) on behalf of the LHCf collaboration Low-X 26, Gyongyos, Hungary, 6- Jun 26

2 The LHCf Collaboration *,** Y.Itow, * Y.Makino, * K.Masuda, * Y.Matsubara, * E.Matsubayashi, *** H.Menjo, * Y.Muraki, *,** T.Sako, * K.Sato, * M.Shinoda, * M.Ueno, * Q.D.Zhou * Institute for Space-Earth Environmental Research, Nagoya University, Japan ** Kobayashi-Maskawa Institute, Nagoya University, Japan *** Graduate School of Science, Nagoya University, Japan K.Yoshida Shibaura Institute of Technology, Japan T.Iwata, K.Kasahara, T.Suzuki, S.Torii Waseda University, Japan Y.Shimizu, T.Tamura Kanagawa University, Japan N.Sakurai Tokushima University, Japan M.Haguenauer Ecole Polytechnique, France W.C.Turner LBNL, Berkeley, USA O.Adriani, E.Berti, L.Bonechi, M.Bongi, G.Castellini, R.D Alessandro, P.Papini, S.Ricciarini, A.Tiberio INFN, Univ. di Firenze, Italy A.Tricomi INFN, Univ. di Catania, Italy 2

3 Outline Introduction LHCf experiment: detector, results. A MC study about diffractive and non-diffractive interaction contribution to the LHCf spectrum. ATLAS-LHCf common operation (MC study). Detector acceptance Efficiency and purity of diffraction identification by common data Low mass diffraction selection Summary

4 The LHCf experiment Measure hadronic production cross section of neutral particles emitted in the very forward region of LHC. To afford the data for verifying and improving the hadronic interaction models. LHCf and ATLAS are observing the particles from the same collisions, but different position Neutron LHCf Arm 4m 4m Collision Gamma LHCf Arm2 LHCf detectors are sensitive to the soft processes 4

5 Particle density and energy flow at TeV Most of secondary particles concentrate to the center dn/dη dn/dη PYTHIA8 η distrobution Multiplicity total non diffractive X-B sigle diffractive A-X sigle diffractive X-X double diffrcative The most energetic secondary particles emitted to the very forward region (LHCf sensitive region) de/dη de/dη PYTHIA8 E-η distrobution total non diffractive X-B sigle diffractive A-X sigle diffractive X-X double diffrcative Energy-flow ATLAS LHCf 4 2 ATLAS LHCf η Neutron LHCf Arm η η=-2. η= η η=2. η Gamma Collision LHCf Arm2

6 The LHCf calorimeter Two imaging sampling shower calorimeters 44r.l. tungsten, 6 layers of GSO scintillators and 4 position sensitive layers The η coverage of the calorimeter: η >8.4 Arm detector Position sensor: 4XY GSO-bar hodoscope + MAPAT Arm2 detector Position sensor: 4XY silicon strip detectors γ π γ n Energy resolution:(>gev) <% for photons 4% for neutrons Position resolution: <2μm for photons <mm for neutrons n γ γ π 6

7 Operations and schedule at the LHC December 29 ~ July 2 9GeV 7TeV January, February~ 2 (only arm2) 2.76TeV June 2 TeV November or December 26 8.TeV (only arm2) 7

8 Results Photon Neutron π p+p 9GeV Phys. Lett. B 7, (22)298- p+p 2.76TeV arxiv: p+p 7TeV Phys. Lett. B 7, (2)28-4 Phys. Lett. B 7, (2)6-66 Phys. Lett. D 86, (22) 92 + arxiv: p+p TeV Preparing On-going p+pb.2tev Phys. Rev. C 89, (24) 629 p+pb 8.TeV 8

9 π was reconstructed from the two decayed γ observed by the LHCf π at s=7tev, p+p Type I π Type II π Good agreement with QGSJET-II-4 EPOS-LHC at PT<. is OK 9

10 Neutron at s=7tev, p+p Forward neutron measurement can give constraint of forward baryon production in the models. No model can represent the data Models give a large discrepancy at η>.76 DPMJET represent the data better than the other models at 8.8<η<9.22

11 - dn [GeV ] Photon at s=tev, p-p η>.94 LHCf s=tev photon η >.94, φ=8 Ldt=.9+.9nb Preliminary - 8.8<η<8.99 LHCf s=tev photon 8.8<η<8.99, φ=2 - Ldt=.9+.9nb Preliminary /N ine Data QGSJET II-4 EPOS-LHC DPMJET.6 SIBYLL 2. PYTHIA 8.22 ] - dn [GeV /N ine 4 4 MC/Data 2 MC/Data Energy Energy

12 What s the source of the difference No MC simulation model can represent LHCf data perfectly Hard interactions can be predicted by using perturbative QCD. Soft interactions dominate by non-perturbative QCD, phenomenological models base on Regge theory proposed Diffractive dissociation belong to soft process. measurement is difficult issue for experiment. especially, low mass diffraction. 2

13 Diffractive dissociation contribute 2%~% of total cross sections. P Pomeron quantum number of vacuum P P2 P X P M X X M X Rapidity gap P 2 P Y M Y (a) (b) (c) Single-diffraction Double-diffraction Central-diffraction P P 2 P P P 4 P X was described by pemeron based model, but the technic of calculation in each model is a little different EPOS-LHC : cut diagrams (pomeron) QGSJET-II-4: renormalized pomeron flux SIBYLL2. : eikonal picture

14 Monte Carlo study about diffractive and non-diffractive interaction contribution to LHCf spectrum 4

15 Investigation of photon spectrum collisions: diffraction + non-diffraction = +DD+CD The excess of PYTHIA8 at E>TeV due to over contribution from diffraction

16 Photon spectrum comparison η>.94 dn γ /N EPOS-LHC p-p, s = TeV η>.94 QGSJET-II-4 p-p, s = TeV η>.94 Model comparison = diff. + non-diff. EPOS-LHC QGSJET-II-4 dn γ /N SIBYLL2. p-p, s = TeV η>.94 dn γ /N PYTHIA822 p-p, s = TeV η>.94 SIBYLL2. PYTHIA EPOS-LHC Models/ LHC 6

17 Investigation of PYTHIA8 diffraction dn γ /N EPOS-LHC p-p, s = TeV η>.94 η>.94 QGSJET-II-4 p-p, s = TeV η>.94 Pomeron flux options in PYTHIA dn γ /N PYTHIA822 DL p-p, s = TeV η>.94 dn γ /N PYTHIA822 p-p, s = TeV η>.94 EPOS-LHC Models/ arxiv:.894v Regge trajectory: αp(t)=.8+.2t as default PYTHIA8DL gives better agreement to ATLAS n(mbts) distribution [ATLAS-CONF- 2-8]. However,it give too much diffraction at E>TeV to LHCf spectra 7

18 Neutron spectrum comparison dn n /N EPOS-LHC p-p, s = TeV η>.94 η>.94 QGSJET-II-4 p-p, s = TeV η>.94 dn n SIBYLL2. p-p, s = TeV η>.94 dn n SIBYLL2. p-p, s = TeV η>.94 /N /N EPOS-LHC Models/ Dominated by diff. or non-diff.? Increased baryon pair production (SIBYLL2.->2.), non-diff. production increased. 8

19 Prospects for ATLAS-LHCf common analysis 9

20 ATLAS-LHCf common operation LHCf ATLAS Final trigger DATA record LID hardware signals Final trigger DATA record Beam condition β*=9m μ=.~. Common data acquisition for the minimum bias measurement. LHCf detectors were incorporated into ATLAS readout system. LHCf triggers ATLAS with trigger rate ~4Hz. The event matching was done offline by using ATLAS LID. Event matching succeed, data analysis on going 2

21 Detector acceptance p p2 Δη p X M(x) ξ=(m(x)/ s ) 2 =-XF ~ e -Δη Trigger efficiency (only with ) Trigger condition of LHCf Photon: Eγ > 2GeV Neutron: En > GeV ATLAS Pass track selection Nhit>2 PYTHIA has different fragmentation function? LHCf and ATLAS cover different diffractive mass range Efficiency ATLAS-CONF-2-8 LHCf preliminary M(x)<2GeV EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA822 log (ξ) 2

22 LHCf event selection w/ ATLAS central trackers Δη Rapidity gap ATLAS Inner detector (tracking system) Condition: Charged particle (PT >MeV) number at η <2. Diffractive like (ATLAS veto) Tracks = Tracks <= Tracks <=2 Tracks <= Efficiency Purity Efficiency.8.6 EPOS-LHC p-p, s = TeV ATLAS veto: charged, -2.<η<2., P >MeV T Tracks= Tracks= Tracks=2 Tracks=.4 identification: No charged particle (tracks=) at η <2. was employed in this analysis.2 Non-Diff Central-Diff Single-Diff Double-Diff 22

23 LHCf photon spectrum w/ ATLAS veto dn γ /N EPOS-LHC p-p, s = TeV η>.94 ATLAS QGSJET-II-4 p-p, s = TeV η>.94 : MC true ATLAS veto: tracks=@ η overlap ATLAS veto dn γ /N SIBYLL2. p-p, s = TeV η>.94 dn γ /N PYTHIA822 p-p, s = TeV η>.94 high diff. selection purity Miss selection efficiency = LHCf _ event@atlasveto LHCf _ Diff. Efficiency.. η>.94 purity = Diff.@ATLASveto LHCf _ event@atlasveto Purity EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA High purity model independently. Efficiency ~%, EPOS and QGSJET give almost consistent efficiency. 2

24 LHCf neutron spectrum w/ ATLAS veto η> <η<8.99 dn n /N EPOS-LHC p-p, s = TeV η>.94 QGSJET-II-4 p-p, s = TeV η>.94 dn n /N EPOS-LHC p-p, s = TeV 8.8< η<8.99 ATLAS dn n /N QGSJET-II-4 p-p, s = TeV dn n SIBYLL2. p-p, s = TeV η>.94 dn n PYTHIA822 p-p, s = TeV η>.94 dn n SIBYLL2. p-p, s = TeV 8.8<η<8.99 dn n PYTHIA822 p-p, s = TeV 8.8<η<8.99 /N /N n /N /N n E E Efficiency. η>.94 Efficiency. 8.8<η< Purity Purity EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA822. EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA822 DL

25 LHCf π spectrum w/ ATLAS veto <PT<.2.8<PT<. /σ EPOS-LHC p-p, s = TeV <P <.2 T QGSJET-II-4 p-p, s = TeV <P <.2 T /σ EPOS-LHC p-p, s = TeV.8<P <. T /σ QGSJET-II-4 p-p, s = TeV.8<P <. T /σ SIBYLL2. p-p, s = TeV <P <.2 T /σ PYTHIA822 p-p, s = TeV <P <.2 T /σ P z SIBYLL2. p-p, s = TeV.8<P <. T /σ P z PYTHIA822 p-p, s = TeV.8<P <. T P z P z P z P z Efficiency. <P T <.2 Efficiency..2<P T <.4.. Purity P z Purity P z. EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA822. EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA P z P z 2

26 Diffractive mass distribution (ξ) dn/dlog (pp->xp) EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA822 PYTHIA822DL Pomeron flux options in PYTHIA 4 2 ξ=(m(x)/ s ) 2 =-XF ~ e -Δη log (ξ) arxiv:.894v log(ξ) distribution of represents the pomeron flux implemented in the model. Large discrepancy exists between models Pomeron flux is an extremely important parameter for modeling diffraction 26

27 Low mass diffraction CMS-PAS-FSQ-2- The inefficiency parts of ATLAS-veto are high mass diff.. ATLAS-LHCf can access the low mass single diffraction region, with high efficiency, experimentally. Efficiency EPOS-LHC QGSJET-II-4 SIBYLL2. PYTHIA822 (ξ)[mb] dσ/dlog 4 2 QGSJET-II-4 p-p, s = TeV M(x)<GeV M(x)<GeV (pp -> Xp) w/ ATLAS veto.2. log (ξ) 2 log (ξ) 27

28 Summary LHCf has taken data in p-p and p-pb collisions at different energies, results have been published about photon, neutron and π No models represent the data perfectly The identification of diffraction can verify and improve the hadronic interaction models. The efficiency and purity of diffractive event identification by ATLAS-LHCf common operation were estimated. - The efficiency of diffraction identification is approximately %, with 99% purity. LHCf detectors have high sensitivity at log(ξ) < -6 Application of ATLAS veto to the LHCf data purifies low mass diffraction event samples Stay Tuned 28

29 Backup 29

30 What to be calibrated by accelerators Hard interactions can be predicted by using perturbative QCD. Soft interactions dominate by non-perturbative QCD, Phenomenological models base on Regge theory proposed Proton Neutron Neutral meson Charged meson Gamma Muon Neutrino Key parameters Inelastic cross section(interaction mean free path) TOTEM, ATLAS, CMS etc. Multiplicity Central detector Inelasticity (k = -Plead/Pbeam) LHCf, ZDC, etc. Forward energy spectrum LHCf, ZDC, etc. Nuclear effect LHCf, ALICE, etc.

31 Hadronic interaction models km ΔXmax indicates the different primary mass composition Iron Proton Models uncertainties Altitude(km) 4. km (6g/cm 2 ).4 km (87g/cm 2 ) Sea level (g/cm 2 ) Xmax Xmax Air showers ΔXmax The issue to interpret the air shower data: The limitations in modeling of hadronic interactions in air shower and largely unknown model uncertainties.

32 Detection efficiency of photon LHCf#Arm2 LHCf#Arm Efficiency LHCf p-p s=tev Arm-Large Tower Photon Arm-Large Tower Efficiency LHCf p-p s=tev Arm2-Large Tower Photon Arm2-Large Tower. 2 4 E γ. 2 4 E γ Efficiency LHCf p-p s=tev Arm-Small Tower Photon Arm-Small Tower Efficiency LHCf p-p s=tev Arm2-Small Tower Photon Arm2-Small Tower. 2 4 E γ. 2 4 E γ Threshold for Arm small tower and large tower are 76,2GeV, respectively. Threshold for Arm2 small tower and large tower are and GeV. 2

33 LHCf detector performance (Arm2) Neutron Energy resolution of TeV Position resolution of TeV

34 Systematic uncertainties (preliminary) Iterms Arm η <.94 Arm 8.99<η<.8 Energy scale -%, +4% -28%, +2% PID correction ±% ±2.% Beam center ±2% ±% Multi hit performance ±2% ±% Multi hit correction -%, +2% -9%, +4% Luminosity ±% ±% Normalized Errors Size... Energy Scale Beam Center PID correction Multi-Hit Performance Multi-Hit Correction Luminosity Systematic Errors (Arm) Rapidity- Normalized Errors Size... Energy Scale Beam Center PID correction Multi-Hit Performance Multi-Hit Correction Luminosity Systematic Errors (Arm) Rapidity Photon Energy Photon Energy 4

35 UPC process at p-pb impact parameter b γ* Pb Ultra Peripheral Collisions (UPCs) If b > Rp+RPb, hadron interaction is strongly suppressed and proton collides with electro- magnetic Cield of Pb, of which strength is proportional to Z 2. The EM interaction can be described as a collision between proton and quasi- photon. Exp.) p+pb X+ Pb p + γ* X In UPCs, what can we see at zero degree of collision? = in LHCf LHCf had operations with p+pb collisions of snn =.2 TeV in 2 LHCf measured the energy spectra of γ, π, neutron inclusively.

36 Energy Spectra - Hadron like -(neutron) Events / GeV 4 2 LHCf-Tower Small(TS), η < -9.6 LHCf-Tower Large(TL), -9. < η < -8.4 ATLAS-LHCf Internal p-pb, s NN =.2 TeV LHCf-TS, Hadron like w/o selection n sel = > n sel Events / GeV 4 2 ATLAS-LHCf Internal p-pb, s NN =.2 TeV LHCf-TL, Hadron like w/o selection n sel = > n sel ΔE/E = 4% Energy Energy Clear difference between spectra of nsel= and of nsel>. Harder spectrum of nsel= due to contribution of Δ resonance at UPCs 6

37 Scattering angle distribution sr] -2 dn/dω [events/ ATLAS-LHCf Preliminary Hadron like, E > GeV p+pb, =.2 TeV s NN w/o selection n sel > } MC (UPC+QCD) MC (QCD) } Data with the event selection by number of tracks in ATLAS; nsel MC with the selection by process Scattering angle [µrad] Note) The sum of UPC and QCD simulations was normalized to all data in the range from µrad to 2 µrad. Clear concentration at zero degree with events of nsel=. Similar distribution of nsel> as one of MC (QCD) The joint analysis clearly helps to study the forward particle production with categorizing the type of interaction. 7

38 8 Impact of diffraction collisions to Xmax K= ΔE/E = exp(-δη) << (asticity) (ΔE: the energy loss of the leading secondary nucleon). diffraction collision is relate to the Xmax The higher rate of Diffractive collision, the deeper Xmax Δη LHCf LHCf S. Ostapchenko, et al., Phy. Rev. D 89, 749 (24) dσsd/dδη[mb] σ σ + σ DD QGSJET-Ⅱ-4 Δη Option σ σ + σ DD σ σ + σ DD QGSJET-Ⅱ-4 Option + Option - Option + Δη Δη

39 Impact of diffraction collisions to X u max Gamma Neutron Collision LHCf Arm LHCf Arm2 Weak influence on EM Xmas Cumulative effect for X u max Neutron (baryon) and gamma (pair production from π meson) are detectable for LHCf detectors T. Pieorg, HESZ 2 9

40 Photon at s=7tev, p+p 4

41 Consistence of Arm and Arm2 LHCf s=tev photon η >.94, φ=8 Ldt=.9+.9nb Preliminary - LHCf s=tev photon 8.8<η<8.99, φ=2 Ldt=.9+.9nb Preliminary - Y [mm] dn [/GeV] ine dn [/GeV] ine 4 2 /N /N Data(Arm) Syst. Error(Arm) Data(Arm) Syst. Error(Arm) Data(Arm) Syst. Error(Arm2) Data(Arm) Syst. Error(Arm2) 2 4 X [mm] Energy Energy 4

42 LHCf-ATLAS Event matching Consistent 42

43 Photon spectrum comparison II 8.8<η<8.99 dn γ /N EPOS-LHC p-p, s = TeV 8.8< η<8.99 QGSJET-II-4 p-p, s = TeV 8.8< η<8.99 dn γ /N SIBYLL2. p-p, s = TeV 8.8< η<8.99 dn γ /N PYTHIA822 p-p, s = TeV 8.8< η< EPOS-LHC Models/

44 Photon spectrum comparison η> <η<8.99 dn γ /N EPOS-LHC p-p, s = TeV η>.94 QGSJET-II-4 p-p, s = TeV η>.94 dn γ /N EPOS-LHC p-p, s = TeV 8.8< η<8.99 dn γ /N QGSJET-II-4 p-p, s = TeV 8.8< η<8.99 dn γ /N SIBYLL2. p-p, s = TeV η>.94 dn γ /N PYTHIA822 p-p, s = TeV η>.94 dn γ /N SIBYLL2. p-p, s = TeV 8.8< η<8.99 dn γ /N PYTHIA822 p-p, s = TeV 8.8< η< EPOS-LHC Models/ EPOS-LHC Models/

45 Neutron spectrum comparison dn n EPOS-LHC p-p, s = TeV η>.94 η>.94 QGSJET-II-4 p-p, s = TeV η>.94 dn n EPOS-LHC p-p, s = TeV 8.8<η< <η<8.99 dn n QGSJET-II-4 p-p, s = TeV 8.8<η<8.99 /N /N /N dn n SIBYLL2. p-p, s = TeV η>.94 dn n PYTHIA822 p-p, s = TeV η>.94 dn n SIBYLL2. p-p, s = TeV 8.8<η<8.99 dn n PYTHIA822 p-p, s = E TeV 8.8<η<8.99 /N /N /N /N EPOS-LHC Models/ EPOS-LHC Models/

46 π spectrum comparison EPOS-LHC p-p, s = TeV <P <.2 T <PT<.2 QGSJET-II-4 p-p, s = TeV <P <.2 T EPOS-LHC p-p, s = TeV.8<P <. T.8<PT<. QGSJET-II-4 p-p, s = TeV.8<P <. T /σ /σ /σ SIBYLL2. p-p, s = TeV <P <.2 T PYTHIA822 p-p, s = TeV <P <.2 T P z SIBYLL2. p-p, s = TeV.8<P <. T P z PYTHIA822 p-p, s = TeV.8<P <. T /σ /σ /σ /σ P z P z P z P z EPOS-LHC Models/ P z P z P z EPOS-LHC Models/ P z P z P z 46

47 dn n /N Low mass diffraction (photon) EPOS-LHC p-p, s = TeV η>.94 LM η>.94 dn n /N QGSJET-II-4 p-p, s = TeV η>.94 LM M(x)<GeV dn n /N EPOS-LHC p-p, s = TeV 8.8< η< <η<8.99 LM dn n /N QGSJET-II-4 p-p, s = TeV 8.8< η<8.99 LM dn n /N SIBYLL2. = TeV p-p, s PYTHIA822 p-p, s = TeV η>.94 LM dn n /N η>.94 LM dn n /N SIBYLL2. p-p, s = TeV 8.8<η<8.99 LM dn n /N PYTHIA822 p-p, s = TeV 8.8<η<8.99 LM dn n /N EPOS-LHC p-p, s = TeV η>.94 ATLAS VETO LM QGSJET-II-4 p-p, s = TeV η>.94 ATLAS VETO LM dn n /N EPOS-LHC p-p, s = TeV 8.8< η<8.99 ATLAS VETO LM dn n /N QGSJET-II-4 p-p, s = TeV 8.8< η<8.99 ATLAS VETO LM dn n /N SIBYLL2. p-p, s = TeV η>.94 ATLAS VETO LM PYTHIA822 η>.94 p-p, s = TeV ATLAS VETO LM dn n /N SIBYLL2. p-p, s = TeV 8.8< η<8.99 ATLAS VETO LM dn n /N PYTHIA822 p-p, s = TeV 8.8< η<8.99 ATLAS VETO LM

48 dn n /N Low mass diffraction (neutron) EPOS-LHC p-p, s = TeV η>.94 η>.94 QGSJET-II-4 p-p, s = TeV η>.94 M(x)<GeV dn n /N EPOS-LHC p-p, s = TeV 8.8<η< <η<8.99 LM dn n /N QGSJET-II-4 p-p, s = TeV 8.8<η<8.99 LM LM LM dn n /N SIBYLL2. p-p, s = TeV η>.94 PYTHIA822 η>.94 p-p, s = TeV dn n /N SIBYLL2. p-p, s = TeV 8.8<η<8.99 LM dn n /N PYTHIA822 p-p, s = TeV 8.8<η<8.99 LM LM LM dn n /N EPOS-LHC p-p, s = TeV η>.94 ATLAS VETO LM dn n /N QGSJET-II-4 p-p, s = TeV η>.94 ATLAS VETO LM dn n /N EPOS-LHC p-p, s = TeV 8.8< η<8.99 ATLAS VETO LM dn n /N QGSJET-II-4 p-p, s = TeV 8.8< η<8.99 ATLAS VETO LM dn n /N SIBYLL2. p-p, s = TeV η>.94 ATLAS VETO LM dn n /N PYTHIA822 p-p, s = TeV η>.94 ATLAS VETO LM dn n /N SIBYLL2. p-p, s = TeV 8.8<η<8.99 ATLAS VETO LM dn n /N PYTHIA822 p-p, s = TeV 8.8<η<8.99 ATLAS VETO LM

49 /σ EPOS-LHC p-p, s = TeV <PT <.2 Low mass diffraction (π ) <PT<.2 LM /σ QGSJET-II-4 p-p, s = TeV <PT <.2 LM M(x)<GeV /σ EPOS-LHC p-p, s = TeV.8<PT <..8<PT<. LM /σ QGSJET-II-4 p-p, s = TeV.8<PT <. LM /σ P z SIBYLL2. p-p, s = TeV <P <.2 T LM /σ P z PYTHIA822 p-p, s = TeV <P <.2 T LM /σ P z SIBYLL2. p-p, s = TeV.8<P <. T LM /σ P z PYTHIA822 p-p, s = TeV.8<P <. T LM P z P z P z P z EPOS-LHC p-p, s = TeV <PT <.2 ATLAS VETO LM QGSJET-II-4 p-p, s = TeV <PT <.2 ATLAS VETO LM EPOS-LHC p-p, s = TeV.8<PT <. ATLAS VETO LM QGSJET-II-4 p-p, s = TeV.8<PT <. ATLAS VETO LM /σ /σ /σ /σ SIBYLL2. p-p, s = TeV <P <.2 T ATLAS VETO LM PYTHIA822 p-p, s = TeV <P <.2 T ATLAS VETO LM /σ P z SIBYLL2. p-p, s = TeV.8<P <. T ATLAS VETO LM /σ P z PYTHIA822 p-p, s = TeV.8<P <. T ATLAS VETO LM P z P z P z P z 49