Diffractive and Exclusive Production of Dijets and W/Z at...

Low x 2008, Kolymbari-Crete, Greece Diffractive and Exclusive JJ and W/Z at CDF K. Goulianos 1

Diffractive and Exclusive Production of Dijets

and W/Z at CDF

K. GoulianosThe Rockefeller Universityand the CDF collaboration

A bit of history…Diffraction in the70s the Pomeron unveiled!

Opening night at Chez Leon - Fermilab (1989)

(right) Greg Snow on violin (Ph.D thesis: first observation of diffractive γ dissociation)

At the Gorge of Samaria (1980)

w/R. Feynman – a day of jokes!

Contents IntroductionDijetsW/Z

Introduction

SD DD DPE SDD=SD+DD

JJ, ee, μμ, γγ

Soft and hard diffraction @ CDF

JJ, b, J/ψ,

exclusive

SD kinematics

dN/dη

p p’

p’rap-gap

Δη=-lnξ

Lpξ ⋅

Breakdown of factorization –

ZEUS and H1 vs. CDF

ξxβ =H1

CDFKG, PLB 358 (1995) 379

1dtdξξ)(t,f0.1

ξIP/p

=∫ ∫−∞=

softγ*e

Magnitude:

same suppression factor in soft and hard diffraction!Shape of β

distribution:

ZEUS, H1, and Tevatron

why different shapes?

All fractions ~ 1% (differences due to kinematics)

~ uniform suppression~ FACTORIZATION !

Hard diffractive fractions –

dN/dη

gap)( ++→ Xpp

1.45 +/-

0.25J/ψ

0.62 +/-

0.115 +/-

0.75 +/-

0.10JJ

Fraction %Fraction:SD/ND ratio@ 1800 GeV

FACTORIZATION !

Multi-gap diffraction –

Run Irestoring factorization

FD jj(β

from DPE/SD , 0.01 ≤ ξ ≤ 0.03

from SD/ND , 0.035 ≤ ξ ≤ 0.095

ND jetjet

SD jetjet

DPE jetjet

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

w/preliminary pdf’s

( )ξ1

β1~ξβ,FD

jj ⋅ Pomeron

dominated

constantdξ

dσincl ∝

( ) 0.10.90.11.0Djj ξ

1ξβ,F ±± ⋅∝

dependence of FDjj

– Run I

Diffractive structure function –

Run II Q2

dependence

ETjet ~ 100 GeV !

Small Q2 dependence in region 100<Q2<10 000 GeV2where each dσND/dET dσND/dET vary by a factor of ~104

The Pomeron evolves as the proton !

Diffractive structure function –

Run II t -

dependence

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

Fit dσ/dt

to a double exponential:

Same slope over entire region of0 < Q2

< ~ 10 000 GeV2

across soft and hard diffraction!

Looks like…

… the underlying diffractive PDF on a hard scale is similar to the proton PDF except for small differences - presumably due to the requirement of combining with the soft PDF to form a spin 1 color singlet with vacuum quantum numbers.

Diffractive W/Z production

Diffractive W production probes the quark content of the Pomeron– To leading order,

the W is produced by a quark in the Pomeron

Production by gluons is suppressed by a factor of αS, and can be distinguished from quark production by an associated jet

Diffractive W/Z -

motivation

• In Run I, by combining diffractive dijet production with diffractive W production we determined the quark/gluon content of the Pomeron ===

• In Run II we aim at determining the diffractive structure function for a more direct comparison with HERA.

• To accomplish this we use:New forward detectorsNew methodologyMore data

Phys Rev Lett 78, 2698 (1997)Fraction of W events due to SD Rw=[1.15±0.51(stat)±0.20(syst) ]%

for ξ<0.1 integrated over t

DIS @ JJ

The DF II detectors

RPS acceptance ~80% for 0.03 < x < 0.1 and |t| < 0.1

The MiniPlugs

Using RPS information:

No background from gaps due to multiplicity fluctuationsNo gap survival probability systematicsThe RPS provides accurate event-by-event ξ measurementDetermine the full kinematics of diffractive W production by

obtaining ην

using the equation:

This allows the determination of:W mass xBj

Diffractive structure function

νηTcalRPS es

Eξξ −/=−

Diffractive W/Z analysis

towers

Tcal es

Eξ −∑=

W/Z selection requirements

cm60|Z|GeV120M40

GeV25MGeV25(pE

cm60|Z|

GeV116M66

GeV25(pE

Standard W/Z selection

Diffractive W/Z selectionRPS trigger counters - MIPRPS track - 0.03< ξ <0.10, |t|<1 W 50 < MW(ξRPS,ξcal) < 120Z ξcal < 0.1

Reconstructed diffractive W mass

Rejection of multiple interaction events

ND dijetw/soft SDoverlap

Diffractive W/Z resultsRW (0.03 < ξ < 0.10, |t|<1)= [0.97 ± 0.05(stat) ± 0.11(syst)]%

Run I: RW =1.15±0.55 % for ξ<0.1 estimate 0.97±0.47 % in 0.03 < ξ < 0.10 & |t|<1)

RZ (0.03 < x < 0.10, |t|<1)= [0.85 ± 0.20(stat) ± 0.11(syst)]%

DØ Phys Lett B 574, 169 (2003) Rw=[5.1±0.51(stat)±0.20(syst)]%gap acceptance Agap=(0.21±4)%

uncorrected for Agap

RW=[0.89+0.19-0.17 ]% RZ=[1.44+0.61-0.52 ]%

Stay connected tor results on FDW/Z

CDF PRL 78, 2698 (1997)Rw=[1.15±0.51(stat)±0.20(syst)]% gap acceptance Agap=0.81

uncorrected for Agap

Rw=(0.93±0.44)%(Agap calculated from MC)

CDF/DØ Comparison – Run I (ξ < 0.1)

EXCLUSIVE JJ & HIGGS BOSONS

22H )'pp'p(pM −−+= ΔM~(1-2) GeV Determine spin of H

gap gap

b -jet

Exclusive dijet and Higg production

ExHuMEURL: http://link.aps.org/abstract/PRD/v77/e052004 DOI: 10.1103/PhysRevD.77.052004

The DPE data sample

towers

TCALpbar e

sEξ −∑=

Kinematic distributions

Exclusive dijet signal

mass fraction –

all jets

Exclusive b-jets are suppressedas expected (JZ

= 0 selection rule)Excess observed over POMWIG MC prediction at large Rjj

b-jet dijet

mass fraction

Underlying event

Jet1 vs. Jet2: signal and background regions

POMWIG

A: signal regionB: background region

Background region

Inclusive DPE W/LRG-p data vs. MC

Shape of excess of events at high Rjjis well described by both ExHuME & DPEMC

ExHuME

(KMR): gg gg process(based on

LO pQCD)DPEMC: exclusive DPE MC

based on Regge

theory

ExHuME DPEMCexclusive MC models

HF suppression vs. inclusive signal

HF suppression

Invert HF vertically and compare with 1-MC/DATAgood agreement observed

HF vs. incl

ExHuME vs. DPEMC and vs. data

Measured x-sections favor ExHuME

KMR x 1/3 agrees with dataWithin theoretical uncertainty of +/- factor of 3

σjjexcl/σincl approx. independent of ET

Exclusive dijet x-section vs. Mjj

curve: ExHuME

hadron-level exclusive dijet

cross sections vs. dijet

mass points: derived from CDF excl. dijet

x-sections using ExHuME

Stat. and syst. errors are propagated

from measured cross section uncertainties using Mjj

distribution

shapes of ExHuME

generated data.

SUMMARY HIGGS ?

Introductiondiffractive PDF looks like proton PDF

Diffractive W/Z – RPS dataW diffractive fraction in agreement with Run IW/Z diffractive fractions equal within errorNew techniques developed to enable extracting

the diffractive structure function in W production

Exclusive dijet/(Higgs?) productionResults favor ExHuME over DPEMCPhys. Rev. D 77, 052004 (2008)

BACKUPMeasurements with the MiniPlugsDynamic alignment of RPS detectorsET

jet calibration

Measurements w/the

MiniPlugs

ADC counts in MiniPlug towersin a pbar-p event at 1960 GeV.• “jet” indicates an energy cluster

and may be just a hadron.• 1000 counts ~ 1 GeVMultiplicity of SD and ND events

ENERGY

MP TOWER

STRUCTURE

MULTIPLICITY

@ POSITION

NIM A 430 (1999)

NIM A 496 (2003)

NIM A 518 (2004)

seEΣξ

iηiTiCAL

Dynamic Alignment of RPS DetectorsMethod:

iteratively adjust the RPS X and Y offsets from the nominal beam axis until a maximum in the b-slope is obtained @ t=0.

Limiting factors1-statistics2-beam size3-beam jitter

@ CDF W/lowlum

μm30±

Calibration

Xjjξ - RPSξ = ξΔ

-0.1 -0.05 0 0.05 0.1

Raw Jets (dotted)Entries 160Mean 0.02438RMS 0.01115

Xjjξ - RPSξ = ξΔ

-0.1 -0.05 0 0.05 0.1

80 Raw Jets (dotted)Entries 160Mean 0.02438RMS 0.01115L5 Corrected Jets (dashed)Entries 293Mean 0.004665RMS 0.01315L7 Corrected Jets (shaded)Entries 360Mean 0.00269RMS 0.01364

L5 Corrected Jets (dashed)Entries 293Mean 0.004665RMS 0.01315

Raw Jets (dotted)Entries 160Mean 0.02438RMS 0.01115

CDF Run II Data

> 10 GeVjet1,2TE

< 5 GeVjet3TE

0.095≤ RPSξ ≤0.035 | < 5.9gapη3.6 < |

> 0.8jj

iη- eiT E

i=1,2∑

= Xjjξ

Calibrate Etjet

or ξ, as you wish!

use RPS information to check jet energy corrections

thank you

Diffractive and Exclusive Production of Dijets and W/Z at...

Documents

Single Diffractive Higgs Production at the LHC *

NON-DIFFRACTIVE PRODUCTION OF MESON …jpac/ScatteringRef/1970s/Non-diffractive... · 388 G C Fox, A J Hey, Productzon of meson resonances 2. The L = 1 and 2 quark model states In

Charm production in diffractive DIS and PHP at ZEUS

Double-diffractive production of heavy quarkonia

Diffractive W and Z Production at Tevatron

Measurement of Dijet Production in Diffractive Deep ...arXiv:1111.0584v1 [hep-ex] 2 Nov 2011 DESY 11-166 ISSN 0418-9833 September 2011 Measurement of Dijet Production in Diffractive

Diffractive Optical

Results on Diffractive Vector Meson Production in ZEUS

M. Kozlov, E. Levin, V. Khachatryan and J. Miller-The BFKL Pomeron Calculus in zero transverse dimensions: diffractive processes and survival probability for central diffractive production

Searches for Diffractive Dijet Production Hardeep Bansil University of Birmingham SM Soft QCD meeting 24/10/2011

Diffractive Triggers

Diffractive W/Z and central gaps at CDF IIphysics.rockefeller.edu/dino/myhtml/talks/manchester08... · 2008-12-06 · Diffractive W/Z and central gaps at CDF II K. Goulianos 6-8 December

Measurement of Dijet Production in Diffractive Deep-Inelastic ...sschmitt/talks/dis2015_lrgdijets.pdfDiffractive dijet production in DIS QCD factorisation in diffractive DIS (Collins):

Marta Ruspa, "Inclusive diffraction", DIS 20041 Inclusive diffractive DIS Diffractive cross section and diffractive structure function Comparison with

Diffractive quarkonium production in association with a photon at the LHC *

Diffractive Optical Elements

Issues concerning diffractive Higgs production at the LHC

Quarkonium plus photon at LHC: diffractive production *

Diffractive Quarkonium Production at High Energies

Measurement of dijet production with a leading proton in ......Single diffractive dijet production ๏ Diffractive dijet production is characterized by the presence of a high momentum