ICHEP 2014 Tevatron Energy Scan Findings Surprises Rick

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ICHEP 2014 Tevatron Energy Scan: Findings & Surprises Rick Field University of Florida Outline

ICHEP 2014 Tevatron Energy Scan: Findings & Surprises Rick Field University of Florida Outline of Talk Æ CDF data from the Tevatron Energy Scan. Æ The overall event topology for events with at least 1 charged particle. Æ The “trans. MAX”, “trans. MIN”, “trans. AVE” and “trans. DIF” UE observables. Æ Mapping out the energy dependence: Tevatron to the LHC! Æ Comparisions with the new PYTHIA 8 tunes: CMS Tune CUETP 8 S 1 -CTEQ 6 L and Skands Monash Tune. Æ The UE and DPS. Æ Summary & Conclusions. ICHEP 2014 Valencia, Spain, July 5, 2014 CDF Run 2 300 Ge. V, 900 Ge. V, 1. 96 Te. V Rick Field – Florida/CDF/CMS at the LHC 900 Ge. V, 7 & 8 Te. V 1

Tevatron Energy Scan 900 Ge. V 300 1. 96 Te. V Æ Just before

Tevatron Energy Scan 900 Ge. V 300 1. 96 Te. V Æ Just before the shutdown of the Tevatron CDF has collected more than 10 M “min-bias” events at several center-of-mass energies! 300 Ge. V 12. 1 M MB Events 900 Ge. V 54. 3 M MB Events ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 2

QCD Monte-Carlo Models: High Transverse Momentum Jets “Hard Scattering” Component “Underlying Event” Æ Start

QCD Monte-Carlo Models: High Transverse Momentum Jets “Hard Scattering” Component “Underlying Event” Æ Start with the perturbative 2 -to-2 (or sometimes 2 -to-3) parton-parton scattering and add initial and finalstate gluon radiation (in the leading log approximation or modified leading log approximation). Æ The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or semi -soft multiple parton interactions (MPI). The “underlying event” is“jet” an unavoidable Æ Of course the outgoing colored partons fragment into hadron and inevitably “underlying event” background to most collider observables and observables receive contributions from initial and final-state radiation. having good understand of it leads to more precise collider measurements! ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 3

Jet Observables Æ “Toward” Charged Particle Density: Number of charged particles (p. T >

Jet Observables Æ “Toward” Charged Particle Density: Number of charged particles (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in the “toward” region (not including PTmax) as defined by the leading charged particle, PTmax, divided by the area in h-f space, 2 hcut× 2 p/3, averaged over all events with at least one particle with p. T > 0. 5 Ge. V/c, |h| < hcut. Æ “Toward” Charged PTsum Density: Scalar p. T sum of the charged particles (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in the “toward” region (not including PTmax) as defined by the leading charged particle, PTmax, divided by the area in h-f space, 2 hcut× 2 p/3, averaged over all events with at least one particle with p. T > 0. 5 Ge. V/c, |h| < hcut. Æ “Away” Charged Particle Density: Number of charged particles (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in the “away” region as defined by the leading charged particle, PTmax, divided by the area in h-f space, 2 hcut× 2 p/3, averaged over all events with at least one particle with p. T > 0. 5 Ge. V/c, |h| < hcut. Æ “Away” Charged PTsum Density: Scalar p. T sum of the charged particles (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in the “away” region as defined by the leading charged particle, PTmax, divided by the area in h-f space, 2 hcut× 2 p/3, averaged over all events with at least one particle with p. T > 0. 5 Ge. V/c, |h| < hcut = 0. 8 ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 4

UE Observables Æ “trans. MAX” and “trans. MIN” Charged Particle Density: Number of charged

UE Observables Æ “trans. MAX” and “trans. MIN” Charged Particle Density: Number of charged particles (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in the maximum (minimum) of the two “transverse” regions as defined by the leading charged particle, PTmax, divided by the area in h-f space, 2 hcut× 2 p/6, averaged over all events with at least one particle with p. T > 0. 5 Ge. V/c, |h| < hcut. Æ “trans. MAX” and “trans. MIN” Charged PTsum Density: Scalar p. T sum of charged particles (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in the maximum (minimum) of the two “transverse” regions as defined by the leading charged particle, PTmax, divided by the area in h-f space, 2 hcut× 2 p/6, averaged over all events with at least one particle with p. T > 0. 5 Ge. V/c, |h| < hcut. Overall “Transverse” = “trans. MAX” + “trans. MIN” hcut = 0. 8 Note: The overall “transverse” density is equal to the average of the “trans. MAX” and “Trans. MIN” densities. The “Trans. DIF” Density is the “trans. MAX” Density minus the “trans. MIN” Density “Transverse” Density = “trans. AVE” Density = (“trans. MAX” Density + “trans. MIN” Density)/2 “Trans. DIF” Density = “trans. MAX” Density - “trans. MIN” Density ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 5

“trans. MIN” & “trans. DIF” Æ The “toward” region contains the leading “jet”, while

“trans. MIN” & “trans. DIF” Æ The “toward” region contains the leading “jet”, while the “away” region, on the average, contains the “away-side” “jet”. The “transverse” region is perpendicular to the plane of the hard 2 -to-2 scattering and is very sensitive to the “underlying event”. For events with large initial or final-state radiation the “trans. MAX” region defined contains the third jet while both the “trans. MAX” and “trans. MIN” regions receive contributions from the MPI and beam remnants. Thus, the “trans. MIN” region is very sensitive to the multiple parton interactions (MPI) and beam-beam remnants (BBR), while the “trans. MAX” minus the “trans. MIN” (i. e. “trans. DIF”) is very sensitive to initial-state radiation (ISR) and final -state radiation (FSR). “Trans. MIN” density more sensitive to MPI & BBR. “Trans. DIF” density more sensitive to ISR & FSR. 0 ≤ “Trans. DIF” ≤ 2×”Trans. AVE” “Trans. DIF” = “Trans. AVE” if “Trans. MIX” = 3×”Trans. MIN” ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 6

PTmax UE Data Æ CDF PTmax UE Analysis: “Towards”, “Away”, “trans. MAX”, “trans. MIN”,

PTmax UE Data Æ CDF PTmax UE Analysis: “Towards”, “Away”, “trans. MAX”, “trans. MIN”, “trans. AVE”, and “trans. DIF” charged particle and PTsum densities (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in proton-antiproton collisions at 300 Ge. V, 900 Ge. V, and 1. 96 Te. V (R. Field analysis). Æ CMS PTmax UE Analysis: “Towards”, “Away”, “trans. MAX”, “trans. MIN”, “trans. AVE”, and “trans. DIF” charged particle and PTsum densities (p. T > 0. 5 Ge. V/c, |h| < 0. 8) in proton-proton collisions at 900 Ge. V and 7 Te. V (Mohammed Zakaria Ph. D. Thesis, CMS PAS FSQ-12 -020). Æ Old CMS UE Tunes: PYTHIA 6. 4 Tune Z 1 (CTEQ 5 L) and PYTHIA 6. 4 Tune Z 2* (CTEQ 6 L) and PYTHIA 8 Tune 4 C* (CTEQ 6 L). All 3 were tuned to the CMS leading chgjet “trans. AVE” UE data at 900 Ge. V and 7 Te. V. Similar to Tune 4 C by Corke and Sjöstrand! ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 7

Total Number of Charged Particles Overall average number of charged Æ CDF data at

Total Number of Charged Particles Overall average number of charged Æ CDF data at 1. 96 Te. V, Ge. V, and 300 particles (including all 900 PTmax values). Ge. V on the total number of charged particles (including PTmax) as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 8

Total Number of Charged Particles Æ CMS and CDF data on the total number

Total Number of Charged Particles Æ CMS and CDF data on the total number of charged particles (including PTmax) as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 9

“Associated” Charged Particle Density Æ Corrected CDF data at 1. 96 Te. V, 900

“Associated” Charged Particle Density Æ Corrected CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the “associated” charged particle density in the “toward”, “away”, and “transverse” regions as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. The data are compared with PYTHIA Tune Z 1. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 10

“Associated” Charged Particle Density Æ Corrected CDF data at 1. 96 Te. V, 900

“Associated” Charged Particle Density Æ Corrected CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the “associated” charged particle density in the “toward”, “away”, and “transverse” regions as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. The data are compared with PYTHIA Tune Z 1. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 11

“Associated” Charged PTsum Density Æ Corrected CDF data at 1. 96 Te. V, 900

“Associated” Charged PTsum Density Æ Corrected CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the “associated” charged PTsum density in the “toward”, “away”, and “transverse” regions as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. The data are compared with PYTHIA Tune Z 1. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 12

“trans. MAX/MIN” Nchg. Den Æ Corrected CDF data at 1. 96 Te. V, 900

“trans. MAX/MIN” Nchg. Den Æ Corrected CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the charged particle density in the “trans. MAX” and “trans. MIN” regions as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. The data are compared with PYTHIA 6. 4 Tune Z 1 and Tune Z 2*. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 13

“trans. MAX/MIN” Nchg. Den Æ Corrected CMS data at 7 Te. V and CDF

“trans. MAX/MIN” Nchg. Den Æ Corrected CMS data at 7 Te. V and CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the charged particle density in the “trans. MAX” charged particle density in the “trans. MIN” region as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. The data are compared with PYTHIA Tune Z 1 and Tune Z 2*. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 14

“trans. DIF/AVE” Nchg. Den Æ Corrected CMS data at 7 Te. V and CDF

“trans. DIF/AVE” Nchg. Den Æ Corrected CMS data at 7 Te. V and CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the charged particle density in the “trans. DIF” charged particle density in the “trans. AVE” region as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. The data are compared with PYTHIA Tune Z 1 and Tune Z 2*. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 15

“trans. MAX” Nchg. Den vs Ecm Æ Corrected CMS data at 7 Te. V

“trans. MAX” Nchg. Den vs Ecm Æ Corrected CMS data at 7 Te. V and CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the charged particle density in the “trans. MAX” region as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected to the particle level with errors that include both the statistical error and the systematic uncertainty. ICHEP 2014 Valencia, Spain, July 5, 2014 Æ Corrected CMS and CDF data on the charged particle density in the “trans. MAX” region as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8 with 5 < PTmax < 6 Ge. V/c. The data are plotted versus the center-of-mass energy (log scale). Rick Field – Florida/CDF/CMS 16

“Transverse” Nchg. Den vs Ecm <trans. MIN> = 4. 7 <trans. MAX> = 2.

“Transverse” Nchg. Den vs Ecm <trans. MIN> = 4. 7 <trans. MAX> = 2. 7 Æ Corrected CMS data at 7 Te. V and CDF data Æ Ratio of CMS data at 7 Te. V and CDF data at at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V on the 1. 96 Te. V, 900 Ge. V, and 300 Ge. V to the value charged particle density in the “trans. MAX” at 300 Ge. V for the charged particle density in and “trans. MIN” regions as defined by the “trans. MAX” and “trans. MIN” regions as leading charged particle (PTmax) for charged defined by the leading charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8 (PTmax) for charged particles with p. T > 0. 5 with 5 < PTmax < 6 Ge. V/c. The data are Ge. V/c and |h| < 0. 8 with 5 < PTmax < 6 plotted versus the center-of-mass energy (log Ge. V/c. The data are plotted versus the center scale). -of-mass energy (log scale). The data are compared with PYTHIA Tune Z 1 and Tune Z 2*. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 17

“Trans. MIN/DIF” vs Ecm <trans. MIN> = 5. 7 <trans. MIN> = 4. 7

“Trans. MIN/DIF” vs Ecm <trans. MIN> = 5. 7 <trans. MIN> = 4. 7 <trans. DIF> = 2. 2 <trans. DIF> = 2. 6 The “trans. MIN” (MPI-BBR component) increases much faster with center-of-mass energy than the “trans. DIF” (ISR-FSR component)! Æ Ratio of CMS data at 7 Te. V and CDF data at. Duh!! Æ Ratio of CMS data at 7 Te. V and CDF data at 1. 96 Te. V, 900 Ge. V, and 300 Ge. V to the value at 300 Ge. V for the charged particle density in at 300 Ge. V for the charged PTsum density in the “trans. MIN”, and “trans. DIF” regions as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8 with 5 < PTmax < 6 Ge. V/c. The data are plotted versus the center -of-mass energy (log scale). The data are compared with PYTHIA Tune Z 1 and Tune Z 2*. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 18

“Tevatron” to the LHC CMS CDF CDF Tune Z 2* & 4 C* ICHEP

“Tevatron” to the LHC CMS CDF CDF Tune Z 2* & 4 C* ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 19

“Tevatron” to the LHC CMS CDF Tune Z 2* & 4 C* ICHEP 2014

“Tevatron” to the LHC CMS CDF Tune Z 2* & 4 C* ICHEP 2014 Valencia, Spain, July 5, 2014 CDF Rick Field – Florida/CDF/CMS 20

New UE Tunes Æ New Herwig++ Tune: M. Seymour and A. Siódmok have used

New UE Tunes Æ New Herwig++ Tune: M. Seymour and A. Siódmok have used the CDF ar. Xiv: 1307. 5015 [hep-ph] UE data at 300 Ge. V, 900 Ge. V, and 1. 96 Te. V together with LHC UE data at 7 Te. V to construct a new and improved Herwig++ tune. Æ New PYTHIA 8 Monash Tune: P. Skands, S. Carrazza, and J. Rojo have used the CDF UE data at 300 Ge. V, 900 Ge. V, and 1. 96 Te. V together with LHC data at 7 Te. V to construct a new PYTHIA 8 tune (NNPDF 2. 3 LO PDF). Æ New CMS UE Tunes: CMS has used the CDF UE data at 300 Ge. V, 900 Ge. V, and 1. 96 Te. V together wth CMS UE data at 7 Te. V to construct a new PYTHIA 6 tune (CTEQ 6 L) and two new PYTHIA 8 tunes (CTEQ 6 L and HERAPDF 1. 5 LO PDF). ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS ar. Xiv: 1404. 5630 [hep-ph] CMS-PAS-GEN-14 -001 21

“Tevatron ” to the LHC CMS CDF CDF Æ Shows the “trans. AVE” charged

“Tevatron ” to the LHC CMS CDF CDF Æ Shows the “trans. AVE” charged particle density Æ Shows the “trans. AVE” charged PTsum density as defined by the leading charged particle, PTmax, as a function of PTmax at 300 Ge. V, 900 Ge. V, 1. 96 Te. V, and 7 Te. V compared with the Skands Monash tune. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 22

“Tevatron” to the LHC Æ Shows the “trans. AVE” charged particle density Æ Shows

“Tevatron” to the LHC Æ Shows the “trans. AVE” charged particle density Æ Shows the “trans. AVE” charged PTsum density as defined by the leading charged particle, PTmax, as a function of PTmax at 300 Ge. V, 900 Ge. V, 1. 96 Te. V, and 7 Te. V compared with the CMS tune CUETP 8 S 1 -CTEQ 6 L. Excludes the 300 Ge. V data! ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 23

Predictions at 13 Te. V ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field

Predictions at 13 Te. V ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 24

Predictions at 13 Te. V ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field

Predictions at 13 Te. V ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 25

DPS and the “Underlying Event” Multiple parton interactions (MPI)! 1/(p. T)4→ 1/(p. T 2+p.

DPS and the “Underlying Event” Multiple parton interactions (MPI)! 1/(p. T)4→ 1/(p. T 2+p. T 02)2 “Underlying Event” Having determined the parameters of an MPI model, one can make an unambiguous prediction of seff. In PYTHIA 8 seff depends DPS: Double Parton Scattering primarily on the matter overlap function, which for b. Profile = 3 is determined by Most of the time MPI are much “softer” than the primary “hard” scattering, however, the exponential shape parameter, exp. Pow, occasionally two “hard” 2 -to-2 parton scatterings can occur within the same hadronand the MPI cross section determined by p hadron. This is referred to as double parton scattering (DPS) and T 0 is typically described in and the PDF. terms of an effective cross section parameter, seff, defined as follows: Independent of A and B where s. A and s. B are the inclusive cross sections for individual hard scatterings of type A and B, respectively, and s. AB is the cross section for producing both scatterings in the same hadron-hardon collision. If A and B are indistinguishable, as in 4 -jet production, a statistical factor of ½ must be inserted. ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 26

Sigma-Effective PYTHIA 8 predicts an energy dependence for seff! 20 -30 mb New D

Sigma-Effective PYTHIA 8 predicts an energy dependence for seff! 20 -30 mb New D 0 values Æ Shows the seff values caluclated from the PYTHIA 8 Monash and CMS tune CUETP 8 S 1 -CTEQ 6 L. The seff predicted from the PYTHIA 8 UE tunes is slightly larger than the direct measurements! HERWIG++ Tune UE-ee-5 -CTEQ 6 L 1 seff ≈ 15 mb! ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 27

Summary & Conclusions ÆThe “transverse” = “trans. AVE” region is not a true measure

Summary & Conclusions ÆThe “transverse” = “trans. AVE” region is not a true measure of the energy dependence of MPI since it receives large contributions from ISR and FSR. ÆThe “trans. MIN” (MPI-BBR component) increases much faster with centerof-mass energy than the “trans. DIF” (ISR-FSR component)! Previously we we are should only knew the energy. What dependence of learning “trans. AVE”. allow for a deeper understanding of MPI ÆPYTHIA 6. 4 Tune Z 1 & Z 2* and PYTHIA 8 Tune 4 C* do a fairly good job whichdeperdence will resultofin precisethere is room for in describing the energy themore UE, however predictions at improvement! The parameterization PT 0 the (Ecmfuture ) = PT 0(Ecm/E 0)e seems to work! LHC energies of 13 & 14 Te. V! ÆNew tunes are being constructed that describe both the UE and DPS within the same formalism. Stay tuned! We now have at lot of MB & UE data at 300 Ge. V, 900 Ge. V, 1. 96 Te. V, and 7 Te. V! We can study the energy dependence more precisely than ever before! ICHEP 2014 Valencia, Spain, July 5, 2014 Rick Field – Florida/CDF/CMS 28