Diffractive and Total Cross Sections @ Tevatron and LHCphysics.rockefeller.edu › dino › myhtml › talks › HCP2006_dino.pdf · T P L, m p S M P P X L L 2 = Δ ξ 0.025 2 2 t=−

$Page 1: Diffractive and Total Cross Sections @ Tevatron and LHCphysics.rockefeller.edu › dino › myhtml › talks › HCP2006_dino.pdf · T P L, m p S M P P X L L 2 = Δ ξ 0.025 2 2 t=−$
K. Goulianos

The Rockefeller University

Diffractive and Total Cross Sections @ Tevatron and LHC

HCP 2006Duke University, NC, USA, 22-26 May 2006

CDF results are presented on behalf of the CDF Collaboration

HCP 2006, Duke U, May 22-26 Diffractive ant Total Cross Sections @ Tevatron and LHC K. Goulianos 2

ContentsIntroductionTotal Cross SectionsDiffractionExclusive Production


p-p InteractionsDiffractive:Colorless exchange with vacuum quantum numbers

Non-diffractive:Color-exchange

Incident hadrons retain their quantum numbersremaining colorless

pseudo-DECONFINEMENT

Incident hadrons acquire colorand break apart

CONFINEMENT

POMERON

Goal: understand the QCD nature of the diffractive exchange

rapidity gap


Elastic Scattering

DIFFRACTION PATTERN

PROTON BEAM

TARGETPROTON

PROTON-PROTON ELASTIC SCATTERING

p p' dtdσ

2

π

)(p4

R

cGeV13b

m1R

e~bte~dtdσ 2

2

−

−

⎟⎠⎞

⎜⎝⎛≈⇒=

θ


Diffraction DissociationRT

RL

M

P0

P0

Δ PT Δ PL,

m p

SM

PP X

L

L2

=Δ

=ξ

025.02

2

−=tdMdt

d σ

Momentum loss fraction

COHERENCE CONDITION 1.0

mm

p

≈< πξξ< 0.1

d

?M1~

dMdσwhyBut 22

@Tevatron MX 600 GeV@ LHC 4.4 TeV


Rapidity Gaps

ξ1~

dξdσ

M

1~dM

dσconstantΔηddσ

220t

⇒⇒≈⎟⎟⎠

⎞⎜⎜⎝

⎛

=

p pX p

ξp

Particle production Rapidity gap

η

φ

-ln ξln MX2

ln s

X


Diffractive pp Processes

η

φ

Elastic scattering Total cross section

SD DD DPE SDD=SD+DD

σT=Im fel (t=0)

OPTICALTHEOREM

η

φGAP


Rapidity Gaps in Fireworks


The PhysicsElastic and Total Cross Sections:……….pp pp and pp X

Fundamental Quantum MechanicsFroissart Unitarity Bound……….σT < C ln2s Optical theorem………………………..σT ~Im f(t=0)Dispersion relations………………....Re f(t=0)~Im f(t=0)Is space-time discrete? Measure the ρ-value at the LHC!

Diffraction Dissociation:………………pp pX, pp pXp, pp XGX, pp pXGXNon-perturbative QCD

Soft & hard diffractionFactorizationMulti-gap diffractionDiffraction in QCD:…….……what is the Pomeron?Dark energy?

Exclusive Production:………………….…..pp pp+A (jet+jet, γ+γ, …, H0)Discovery channel

Diffractive Higgs production at the LHC (?)


Tevatron Experiments

InfoExp

RomanPots El σT

Soft diffraction Hard diffraction

p, pbar

CDF-0 p, pbar x x sd

pbar

pbar

p, pbar

D0-I JJ,W,Z,JGJ, …

E710/811(Scint. Counters)

x x sd

CDF-I sd,dd,dpe,sdd JJ,b,J/ψ,W,JGJ

CDF-II sd JJ,W,Z,JGJExclusive JJ,γγ,...

D0-II x x sd,dpe,… JJ,W,Z,JGJ,…Exclusive ???


CDF Run 1-0 (1988-89)Elastic, diffractive, and total cross section

@ 546 and 1800 GeV

Roman Pot Spectrometers

Roman Pot DetectorsScintillation trigger countersWire chamber Double-sided silicon strip detector

Roman Pots with Trackersup to |η| = 7

CDF-I


CDF-I

DIPOLE MAGNETS

ROMAN POTS at 57 m

p- CDF

Scintillator fiber xy-tracker 270 pitch, 2 m lever armx<0.97

x=1

μ

Acceptance: 0 < |t| < 1, 0.03< < 0.1ξ

Run-IC Run-IA,B

HADRON

END PLUG EM

CENTRAL EMCES

EM

Forward(Not-To-Scale)

CPR

CENTRAL MUON

CENTRAL MUON UPGRADE

STEEL ABSORBER

η = 0

Silicon Vertex Detector

Central Muon Extension

Z

Vertex Tracking Chamber

CHAMBERTRAKCING

INTERACTION POINT

DetectorCDF

η = 4.2

η = 2.4

η = 0.9

PLUG

ENDHADRONCENTRAL

BBC

WALL

CENTRAL

SOLENOID

HADRON

END

HADRON

Forward DetectorsBBC 3.2<η<5.9FCAL 2.4<η<4.2

beam


CDF-IIROMAN POT DETECTORS

BEAM SHOWER COUNTERS:Used to reject ND events

MINIPLUG CALORIMETER


CDF & D0 - Run II

Z(m)

D SQ2Q3Q4S A1A2

P1U

P2I

P2O

P1DD2 D1

233359 3323057

Q4Q3Q2

D0

From Barreto’s talk in small-x

LM 2.5<η<4.4VC 5.2<η<5.9

Z(m)

p

D Q2Q3Q4

p

RP3 RP1

2332 3223057

Q4Q3Q2

MP 3.5<η<5.5BSC1 5.5<η<7.5

RP2

S S

BSC4 BSC2BSC3 BSC2 BSC3CDF

CDF & D0:COMPLIMENTARY

COVERAGE


ELASTIC AND TOTAL CROSS SECTIONSAt Tevatron:

CDF and E710/811use luminosity independent method

Optical theorem

Alert:background Ninel yields small σTundetected Ninel yields large σT

( )

inelelt

elT

inelelTt

elT

NNdtdN

NNLdt

dNL

++=⇒

++

=

=

1116

1~&1

11~

02

02

2

ρπσ

σρ

σ

optical theorem


σT and ρ-values from PDG

E710

ρ = ratio of real/imaginary partsof elastic scattering amplitude at t=0

E811

CDF

CDF & UA4

CDF and E710/811 disagree

σT

optical theoremIm fel(t=0)

dispersion relationsRe fel(t=0)E811

N. Khuri and A. Martin:measuring ρ at the LHC tests discreteness of space-time


Total Cross Sections: Regge fitCMG: Covolan, Montagna, and G

PLB 389 (1995) 176

Simultaneous Regge fit to pp, πp, and Kp x-sections using the eikonal approachto ensure unitarity

σ Sε

ε = 1.104 +/- 0.002

σLHC = 115 mb@14 TeV

Bornlevel

DL

E710CDF


Elastic/Total and ρ-values: Regge fitCovolan, Montagna, and G

PLB 389 (1995) 176

Agreement with data on:

b-slopesσel/σT

ρ-valuesUnitarity assured


Other Approaches

σT (LHC) = 107.3 ± 1.2 mb

eg, M. Block, arXiv:hep-ph/0601210 (2006)

fit data using analyticity constraintsM. Block and F. Halzen, Phys. Rev. D 72, 036006

Recall CMG Regge fit: 115 mb


TOTEM experiment @ LHCTotal Cross Section, Elastic Scattering, and Diffraction Dissociation

Aim at 1% accuracy on σT

RP stations

RP stations

CMS


DIFFRACTIONSoft & hard diffraction

Factorization / renormalization

Multi-gap diffraction

Diffraction in QCD

Dark energy ???


Regge theoryσSD exceeds σT at

RenormalizationPomeron flux integral(re)normalized to unity

A unitarity issue)(Mσξ)(t,f

dtdξσd 2

XpIPIP/pSD

2

−•=

KG, PLB 358 (1995) 379

TeV.2s ≈

1dtdξξ)(t,f0.1

ξIP/p

0

tmin

=∫ ∫−∞=

εσ 2~ sSD

Pomeron fluxFactorization


A Scaling Law in Diffraction

14 GeV (0.01 < ξ < 0.03)

20 GeV (0.01 < ξ < 0.03)

546 GeV (0.005 < ξ < 0.03)

1800 GeV (0.003 < ξ < 0.03)

1____

(M2)1+Δ.....

←_____ 546 GeV std.flux prediction

← 1800 GeV std.flux prediction

Δ = 0.05 ________→

Δ = 0.15 _________→

renorm. fluxprediction

_________→

std. and renorm.flux fits

|↑

KG&JM, PRD 59 (1999) 114017

ε≡Δ

Factorization breaks down so as to ensure M2-scaling!

ε

εσ+∝ 12

2

2 )(Ms

dMd

renormalization

1

Independent of S over 6 orders of magnitude in M2 !


The QCD Connection

( ) ytel etsf Δ′+∝ αε),(Im

yφ sy ln=Δ

The exponential rise of σT(Δy’) is dueto the increase of wee partons with Δy’

(E. Levin, An Introduction to Pomerons,Preprint DESY 98-120)

εε σσσ ses oy

oT == ′Δ)(y

φ sy ln=′ΔTotal cross section:power law increase versus s

Elastic cross section:forward scattering amplitude

∼1/αs


y′ΔyΔ

yt Δ,2 independent variables:

( ){ } { }yo

ytp eetFC

yddtd ′ΔΔ′+ ••••=

Δεαε σκσ 22

2

)(

Gap probability

Renormalization removes the s-dependence SCALING

Single Diffraction in QCD

ye Δε2~εε 22ln

minsyssy

y ≈Δ∫ =ΔΔ

t

colorfactor

(KG, hep-ph/0205141)

ε12

2ε

REGGE2 )(M

sdMdσ

+∝


Multi-gap Renormalization

ye Δε2~εε 22ln

minsyssy

y ≈Δ∫ =ΔΔ

Same suppressionas for single gap!

1y′Δ 2y′Δ1yΔ 2yΔ

1y′ 2y

1t 21 yyy Δ+Δ=Δ5 independent variables

2t

( ){ } ( ){ }2122

2-1i1

2

51

5

)( yyo

ytp

ii

eetFCdV

dii ′Δ+′Δ

=

Δ′+

−=

××= ∏∏εαε σκσ

Gap probability Sub-energy cross section(for regions with particles)

colorfactors

(KG, hep-ph/0205141)


p

p

IP

IPp p

η0ηp_ ηp

p

pIP

M1

M2

η

dNdη

ηη maxmin

ln M1 ln M22 2

ln s

ηη maxminp

0η

ln M1 ln M22 2

ln1/ξp ln s’ln s

p p

IP tpM1

IP tp

M2

Double Diffraction Dissociation

One central gap

Double Pomeron Exchange

Two forward gaps

SDD: Single+Double Diffraction

One forward + one central gap

Central and Double Gaps @ CDF


1

10

10 2

10 102

103

√s (GeV)

σ DD (

mb)

for

Δη >

3.0

ReggeRenormalized gap

CDFUA5 (adjusted)

10-1

1

103

sub-energy √s--, (GeV)

gap

frac

tion

Δη >

3.0 CDF: one-gap/no-gap

CDF: two-gap/one-gapRegge predictionRenorm-gap prediction

2-gap

1-gap

210

0

0.1

0.2

0.3

0.4

0.5

103

√s⎯

(GeV)F

ract

ion

of E

vent

s w

ith ξ

p <

0.02

CDF Data: DPE/SD ratio (Preliminary)

Regge + Factorization

Gap Probability Renorm.

Pomeron Flux Renom.

One-gap cross sections are suppressedTwo-gap/one-gap ratios are 17.0=≈ κ

Central & Double-Gap CDF ResultsDifferential shapes agree with Regge predictions

10

10 2

10 3

10 4

10 5

10-6

10-5

10-4

10-3

10-2

10-1

1ξp

X

MX2

Num

ber

of E

vent

s pe

r Δl

ogξ

= 0

.1

Data

DPE MC

SD MC

DPE+SD MC

√s⎯

= 1800 GeV

0.035 ≤ ξ- p ≤ 0.095

| t- p | ≤ 1.0 GeV2

( GeV 2 )1 10 10

210

310

410

510

6CDF Preliminary

10

10 2

10 3

10 4

10 5

0 1 2 3 4 5 6 7

√s=1800 GeV

DATADD + non-DD MCnon-DD MC

Δη0=ηmax-ηmin

even

ts

10 2

10 3

10 4

10 5

0 1 2 3 4 5 6 7Δη0

exp=ηmax-ηmin

even

ts

√s=1800 GeVDATASDD + SD MCSD MC

DD SDD DPE


Dark Energy

P(Δy) is exponentially suppressed

dydN

ρ,ey)P( particlesΔyρ ==Δ −

Rapidity gaps are formed bymultiplicity fluctuations:

Non-diffractive interactions

Δy2εe~0ty)P( =Δ

2lnlnln Msy −=−≈Δ ξ

Rapidity gaps at t=0 grow with Δy:

Diffractive interactions

2ε: negative particle density!

Gravitational repulsion?


HARD DIFFRACTIONDiffractive fractions

Diffractive structure function

factorization breakdown

Restoring factorization

Hard diffraction in QCD

η

dN/dη

JJ, W, b, J/ψ


All ratios ~ 1% ~ uniform suppression~ FACTORIZATION !

Diffractive Fractions @ CDF

gap)( ++→ Xpp

1.45 (0.25)J/ψ

0.62 (0.25)b

0.75 (0.10)JJ

1.15 (0.55)W

Fraction(%)Fraction:SD/ND ratioat 1800 GeV


The diffractive structure function at the Tevatron is suppressed by a factor of ~10 relative to expectation from pdf’s measured by H1 at HERA

Similar suppression factor as in soft diffraction

relative to Regge expectations!

Diffractive Structure Function:Breakdown of QCD Factorization

CDF

H1

β = momentum fractionof parton in Pomeron

Using preliminary pdf’s from


Restoring QCD Factorization

0.1 1

0.1

1

10

100

β

FD jj(β

)

from DPE/SD , 0.01 ≤ ξ ≤ 0.03

from SD/ND , 0.035 ≤ ξ ≤ 0.095

p

p

ND jetjet

0p

p

p

IP

SD jetjet

p

0

p

p

IP

IP

DPE jetjet

p p

η0ηp_ ηp

R(SD/ND)

R(DPE/SD)DSF from two/one gap:factorization restored!

The diffractive structure function measured on the proton side in events with a leading antiproton is NOT suppressed relative to predictions based on DDIS


Diffractive Structure Function:Q2 dependence

ETjet ~ 100 GeV !

Small Q2 dependence in region 100 < Q2 < 10,000 GeV2

Pomeron evolves as the proton!


Diffractive Structure Function:t- dependence

No diffraction dipsNo Q2 dependence in slopefrom inclusive to Q2~104 GeV2

Fit dσ/dt to a double exponential:

Same slope over entire region of0 < Q2 < 4,500 GeV2

across soft and hard diffraction!


valence quarks

antiproton

x=ξ

Hard Diffraction in QCD

proton

deep sea

Derive diffractivefrom inclusive PDFsand color factors

antiproton

valence quarks

p

p


EXCLUSIVE PRODUCTION

H

Measure exclusive jj & γγ Calibrate predictions for H production rates @ LHC

Bialas, Landshoff,Phys.Lett. B 256,540 (1991)Khoze, Martin, Ryskin,Eur. Phys. J. C23, 311 (2002); C25,391 (2002);C26,229 (2002)C. Royon, hep-ph/0308283B. Cox, A. Pilkington,PRD 72, 094024 (2005)OTHER…………………………

Search for exclusive dijets:Measure dijet mass fraction

Look for signal as Mjj 1

( )rscalorimeteallMM

RX

jjjj =

Search for exclusive γγ

Search for events with two high ET gammas and no other activity in the calorimeters or BSCs

KMR: σH(LHC) ~ 3 fbS/B ~ 1 if ΔM ~ 1 GeVClean discovery channel


Exclusive Dijet and γγ Searchb-taqged dijet fractionDijet fraction – all jets

Exlusive b-jets are suppressedby JZ= 0 selection rule

Excess over MC predictions at large dijet mass fractionSystematic uncertainties under study: tune in this summer for results

Exclusive γγBased on 3 events observed:

Good agreement with KMR:

pb0.03(syst)(stat)0.14σ 0.140.04MEAS ±= +

−

pb3)20.04(0.04σKMR −×±=

DIJETS


Looking forward @ LHC

TOTEM/CMS ATLAS

FP420 projectMeasure protons at 420 m from the IP during normal high luminosity running to be used in conjunction with CMS and ATLASFeasibility study and R&D for Roman Pot detector development

Physics aim :pp → p+ X + p (Higgs, New physics, QCD studies)Status: Project funded by the UK


SummaryTEVATRON – what we have learntM2 – scalingNon-suppressed double-gap to single-gap ratiosPomeron: composite object made up from underlying pdf’s subject to color constraints

LHC - what to doElastic and total cross sections & ρ-valueHigh mass 4 TeV and multi-gap diffraction Exclusive production (FP420 project)

Reduced bgnd for std Higgs to study propertiesDiscovery channel for certain Higgs scenarios

Documents

Diffractive and Total Cross Sections @ Tevatron and LHCphysics.rockefeller.edu › dino › myhtml › talks › HCP2006_dino.pdf · T P L, m p S M P P X L L 2 = Δ ξ 0.025 2 2 t=−