Diffraction, saturation, and pp cross-sections at the LHC and beyond Konstantin Goulianos The Rockefeller University A topical conference on elementary particles, astrophysics, and cosmology The to

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 2 CONTENTS  Introduction  Diffractive cross sections  The total cross section  Ratio of pomeron intercept to slope  Conclusions

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 3 Two reasons: one fundamental / one practical.  fundamental  practical: underlying event, triggers, calibrations Why study soft physics?  T optical theorem Im f el (t=0) dispersion relations Re f el (t=0) Diffraction measure  T &  -value at LHC: violation of dispersion relations  sign for new physics Bourrely, C., Khuri, N.N., Martin, A.,Soffer, J., Wu, T.T All MCs based on pre-LHC data are inadequate  need to build robust soft physics MC simulations  saturation   T  dark energy???

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 4 ATLAS: UE data vs MC at 900 GeV  wrt to leading particle at 900 GeV ~30%

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 5 ATLAS: UE data vs MC at 7 TeV  wrt to lead particle at 7 TeV ~30%

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 6 CMS: observation of Diffraction at 7 TeV An example of a beautiful data analysis and of MC inadequacies Pre-approved on 11/11/2012

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 7 Regge theory – values of s o & g? Parameters:  s 0, s 0 ' and g(t)  set s 0 ‘ = s 0 (universal IP)  g(t)  g(0) ≡ g PPP  KG-1995  determine s 0 and g PPP – how? KG-1995: PLB 358, 379 (1995 )

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 8 Global fit to p ± p,  ±, K ± p x-sections  INPUT  RESULTS CMG-1996 PLB 389, 176 (1996) Regge theory eikonalized negligible

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 9 Born Eikonal  T at LHC from CMG global fit   LHC √s=14 TeV: 122 ± 5 mb Born, 114 ± 5 mb eikonal  error estimated from the error in  given in CMG-96 caveat: s o =1 GeV 2 was used in global fit! Compare with SUPERBALL  (14 TeV) = 109 ± 6 mb

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 10 but Peter Landshoff says… How well can we predict the total cross section at the LHC? Authors: P V Landshoff (Submitted on 3 Nov 2008) Abstract: Independently of any theory, the possibility that the large value of the Tevatron cross section claimed by CDF is correct suggests that the total cross section at the LHC may be large. Because of the experimental and theoretical uncertainities, the best prediction is $125\pm 35$ mb. arXiv: v1 [hep-ph]

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 11 The problem is  Unitarity!  d  /dt  sd grows faster than  t as s increases  unitarity violation at high s (similarly for partial x-sections in impact parameter space)  the unitarity limit is already reached at √s ~ 2 TeV

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 12  T SD vs  T (pp & pp) Factor of ~8 (~5) suppression at √s = 1800 (540) GeV KG, PLB 358, 379 (1995) 1800 GeV 540 GeV M ,t,t p p p’  T SD mb √s=22 GeV  RENORMALIZATION MODEL CDF Run I results TT TT

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 13 Diffractive pp/pp Processes   Elastic scatteringTotal cross section SD DDDPESDD=SD+DD  T =Im f el (t=0) OPTICAL THEOREM   GAP

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 14 p-p Interactions Diffractive: Colorless exchange with vacuum quantum numbers Non-diffractive: Color-exchange Incident hadrons retain their quantum numbers remaining colorless pseudo- DECONFINEMENT Incident hadrons acquire color and break apart CONFINEMENT POMERONPOMERON Goal: understand the QCD nature of the diffractive exchange rapidity gap

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 15 Basic and combined (“nested”) diffractive processes multi-gap “nested” process

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 16 Renormalization  the key to diffraction in QCD

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 17 Diffractive gaps definition: gaps not exponentially suppressed p p X p Particle productionRapidity gap   -ln  ln M X 2 ln s X No radiation

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 18  T SD (pp & pp) - data Factor of ~8 (~5) suppression at √s = 1800 (540) GeV  suppressed relative to Regge for √s>22 GeV KG, PLB 358, 379 (1995) 1800 GeV 540 GeV M ,t,t p p p’  T SD mb √s=22 GeV  RENORMALIZATION MODEL CDF Run I results

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 19 M 2 distribution: data KG&JM, PRD 59 (1999)  factorization breaks down to ensure M 2 scaling Regge 1 Independent of s over 6 orders of magnitude in M 2  M 2 scaling  d  dM 2 | t=-0.05 ~ independent of s over 6 orders of magnitude ! data

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 20 Saturation at low Q 2 and small-x figure from a talk by Edmond Iancu

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 21 Gap probability  (re)normalize to unity Single diffraction renormalized – (1) 2 independent variables: t color factor gap probability sub-energy x-section EDS 2009: CORFU-2001: hep-ph/

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 22 Single diffraction renormalized – (2) color factor Experimentally: KG&JM, PRD 59 (114017) 1999 QCD:

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 23 Single diffraction renormalized - (3) set to unity  determine s o

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 24 Single diffraction renormalized – (4)  Pumplin bound obeyed at all impact parameters grows slower than s 

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 25 Scale s o and triple-pom coupling  Two free parameters: s o and g PPP  Obtain product g PPP s o  from  SD  Renormalized Pomeron flux determines s o  Get unique solution for g PPP Pomeron-proton x-section Pomeron flux: interpret as gap probability  set to unity: determines g PPP and s 0 KG, PLB 358 (1995) 379 S o =3.7±1.5 GeV 2 g PPP =0.69 mb -1/2 =1.1 GeV -1

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 26 Saturation glueball? See M.G.Albrow, T.D. Goughlin, J.R. Forshaw, hep-ph>arXiv: Giant glueball with f 0 (980) and f 0 (1500) superimposed, interfering destructively and manifesting as dips (???) √s o

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 27 Multigap diffraction KG, hep-ph/  y

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 28 Rapidity Gaps in Fireworks

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 29 Multigap cross sections Same suppression as for single gap! Gap probabilitySub-energy cross section (for regions with particles) 5 independent variables color factor

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 30 Gap survival probability S =

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 31 The total x-section √s F =22 GeV SUPERBALL MODEL 98 ± 8 mb at 7 TeV 109 ±12 mb at 14 TeV abs/

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 32  SD and ratio of  ' 

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 33 Monte Carlo Strategy for the LHC   T  from SUPERBALL model  optical theorem  Im f el ( t=0 )  dispersion relations  Re f el ( t=0 )  differential  SD  from RENORM  use nested pp final states for pp collisions at the IP­p sub-energy √s‘ Strategy similar to that employed in the MBR (Minimum Bias Rockefeller) MC used in CDF based on multiplicities from: K. Goulianos, Phys. Lett. B 193 (1987) 151 pp “A new statistical description of hardonic and e + e − multiplicity distributions “  T optical theorem Im f el (t=0) dispersion relations Re f el (t=0) MONTE CARLO STRATEGY

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 34 Dijets in  p at HERA from RENORM Factor of ~3 suppression expected at W~200 GeV (just as in pp collisions) for both direct and resolved components K. Goulianos, POS (DIFF2006) 055 (p. 8)

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 35 Dark Energy P(  y) is exponentially suppressed Rapidity gaps are formed by multiplicity fluctuations: Non-diffractive interactions Rapidity gaps at t=0 grow with  y: Diffractive interactions 2  : negative particle density! Gravitational repulsion ?

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 36 SUMMARY  Introduction  Diffractive cross sections  The total cross section  Ratio of pomeron intercept to slope  Monte Carlo strategy for the LHC  Dark energy (?)

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 37 BACKUP

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 38 RISING X-SECTIONS IN PARTON MODEL (see E. Levin, An Introduction to Pomerons,Preprint DESY ) y  Emission spacing controlled by  -strong    : power law rise with energy  s  ’ reflects the size of the emitted cluster, which is controlled by 1 /  s and thereby is related to  y  Forward elastic scattering amplitude assume linear t-dependence

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 39 Diffractive Tevatron p jet reorganize jet

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 40 F D JJ ( , Q 2 Tevatron

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 41 SD/ND dijet ratio vs. x CDF <  < Flat  dependence for  < 0.5 CDF Run I

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 42 Diffractive HERA e Q2Q2 ** p jet  reorganize J. Collins: factorization holds (but under what conditions?) e **  t p IP Pomeron exchangeColor reorganization Results favor color reorganization

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 43 Vector meson production (Pierre Marage, HERA-LHC 2008)  left - why different  vs. W slopes?  more room for particles  right - why smaller b-slope in  *p?  same reason

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 44 Dijets in  p at HERA DIS 2008 talk by W. Slomiński, ZEUS  % apparent rise when E T jet 5  10 GeV  due to suppression at low E T jet !!!

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 45 Unexpected, not understood QCD factorisation not OK Dijets in  p at HERA – 2007 Hadron-like  e Q2Q2 ** p jet  reorganize Direct vs. resolved  the reorganization diagram predicts:  suppression at low Z | P jets, since larger  is available for particles  same suppression for direct and resolved processes

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 46 EXCLUSIVE HIGGS PRODUCTION psec timing   M~(1-2) GeV basically determine spin of H gap -jet  p p H see, e.g.,  detect protons in roman pots in coincidence with b-bbar  use missing mass technique to measure mass  Low QCD bgd from Jz=0 selection rule

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 47 Exclusive Dijet and Higgs Production H DPEMC Phys. Rev. D 77, ExHuME

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 48 Exclusive Dijet x-section vs. M jj Exclusive Dijet x-section vs MC left: the data favor ExHuME (updated DPEMC agrees now with data) right: points derived from CDF excl. di-jet x-sections using ExHuME  predictions for Higgs production should be within factor of 2

K. Goulianos MIAMI 2010, Dec Diffraction, saturation, and pp cross sections at the LHC and beyond 49 The end