Soft and hard diffraction at cdf
This presentation is the property of its rightful owner.
Sponsored Links
1 / 30

Soft and Hard Diffraction at CDF PowerPoint PPT Presentation


  • 88 Views
  • Uploaded on
  • Presentation posted in: General

Soft and Hard Diffraction at CDF. Konstantin Goulianos The Rockefeller University & The CDF Collaboration. Xth Blois Workshop on Elastic and Diffractive Scattering 23-28 June 2003, Helsinki, Finland. Introduction. X. What is hadronic diffraction?. Diffraction dissociation. coherence.

Download Presentation

Soft and Hard Diffraction at CDF

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Soft and hard diffraction at cdf

Soft and Hard Diffraction at CDF

Konstantin Goulianos

The Rockefeller University & The CDF Collaboration

Xth Blois Workshop on Elastic and Diffractive Scattering

23-28 June 2003, Helsinki, Finland

K. Goulianos, Blois Workshop, Helsinki, Finland


Introduction

Introduction

X

What is hadronic diffraction?

Diffraction

dissociation

coherence

KG, Phys. Rep. 101 (1983) 171

K. Goulianos, Low-x Workshop, Nafplion


Diffraction and rapidity gaps

Non-diffractive interactions:

Diffractive interactions:

Diffraction and Rapidity Gaps

  • rapidity gaps are regions of rapidity devoid of particles

rapidity gaps are formed by

multiplicity fluctuations

rapidity gaps, like diamonds,

‘live for ever’

From Poisson statistics:

(r=particle density in rapidity space)

Gaps are exponentially suppressed

  • large rapidity gaps are signatures for diffraction

K. Goulianos, Blois Workshop, Helsinki, Finland


The pomeron

?

The Pomeron

  • Quark/gluon exchange across a rapidity gap:

    POMERON

  • No particles radiated in the gap:

    the exchange is COLOR-SINGLETwith quantum numbers of vacuum

  • Rapidity gap formation:

    NON-PERTURBATIVE

  • Diffraction probes the large distance aspects of QCD:

    POMERON CONFINEMENT

  • PARTONIC STRUCTURE

  • FACTORIZATION

K. Goulianos, Blois Workshop, Helsinki, Finland


Diffraction at cdf in run i

Diffraction at CDF in Run I

PRD 50 (1994) 5518

  • Elastic scattering

  • Total cross section

  • Diffraction

PRD 50 (1994) 5550

SOFT diffraction

Control

sample

PRD PRL PRL PRL

50 (1994) 5535 87 (2001)141802 to be sub’d accepted

HARD diffraction

PRL reference

with roman pots

K. Goulianos, Blois Workshop, Helsinki, Finland


Soft diffraction

Soft diffraction

f

parton model

Factorization & (re)normalization

Pomeron

trajectory

COLOR

FACTOR

Renormalize to unity

KG, PLB 358 (1995) 379

Gap probability

K. Goulianos, Low-x Workshop, Nafplion


Soft single diffraction data

Soft Single Diffraction Data

Total cross section

KG, PLB 358 (1995) 379

Differential cross section

KG&JM, PRD 59 (114017) 1999

REGGE

RENORM

s-independent

  • Differential shape agrees with Regge

  • Normalization is suppressed by factor ~

  • Renormalize Pomeron flux factor to unity

M2 SCALING

K. Goulianos, Blois Workshop, Helsinki, Finland


Central and double gaps

Central and Double Gaps

  • Double diffraction

  • Plot #Events versus Dh

  • Double Pomeron Exchange

  • Measure

  • Plot #Events versus log(x)

  • SDD: single+double diffraction

  • Central gaps in SD events

K. Goulianos, Blois Workshop, Helsinki, Finland


Two gap diffraction hep ph 0205141

Two-Gap Diffraction (hep-ph/0205141)

5 independent variables

color

factor

Gap probability

Sub-energy cross section

(for regions with particles)

Integral

Renormalization removes the s-dependence SCALING

K. Goulianos, Blois Workshop, Helsinki, Finland


Central and double gap results

Central and Double-Gap Results

Differential shapes agree with Regge predictions

DD

SDD

DPE

  • One-gap cross sections require renormalization

  • Two-gap/one-gap ratios are

K. Goulianos, Blois Workshop, Helsinki, Finland


Soft double pomeron exchange

Soft Double Pomeron Exchange

  • Roman Pot triggered events

  • 0.035 < x-pbar < 0.095

    |t-pbar| < 1 GeV 2

  • x-proton measured using

  • Data compared to MC based

    on Pomeron exchange with

    Pomeron intercept e=0.1

  • Good agreement over the entire kinematic region (4 orders of magnitude!)

K. Goulianos, Blois Workshop, Helsinki, Finland


Hard diffraction in run i

Hard diffraction in Run I

BBC

FCAL

CDF Forward Detectors

Rapidity gaps

Antiproton tag

BBC 3.2<h<5.9

FCAL 2.4<h<4.2

Diffractive

dijets

K. Goulianos, Low-x Workshop, Nafplion


Hard diffraction using rapidity gaps

SINGLE DIFFRACTION

DOUBLE DIFFRACTION

X

CDF

D0

W

1.15 (0.55)

JJ

0.75 (0.10)

0.65 (0.04)

b

0.62 (0.25)

J/y

1.45 (0.25)

Hard Diffraction Using Rapidity Gaps

SD/ND gap fraction (%) at 1800 GeV

DD/ND gap fraction at 1800 GeV

  • All SD/ND fractions ~1%

  • Gluon fraction

  • Suppression by ~5 relative to HERA

Just like in ND except for the

suppression due to gap formation

K. Goulianos, Blois Workshop, Helsinki, Finland


Diffractive dijets with leading antiproton

(not detected)

Diffractive Dijets with Leading Antiproton

The diffractive structure function

Bjorken-x of antiproton

Nucleon structure function

Diffractive structure function

ISSUES:1) QCD factorization > is FSD universal?

2) Regge factorization >

?

momentum fraction of parton in IP

METHODof measuring FSD : measure ratio R(x,t) of SD/ND rates for given x,t

set R(x,t)=FSD/FND

evaluate FSD = R * FND

K. Goulianos, Blois Workshop, Helsinki, Finland


Dijets in single diffraction

Dijets in Single Diffraction

Test Regge factorization

Test QCD factorization

Suppressed at the Tevatron

relative to predictions based

on HERA parton densities

Regge factorization holds

!!!

K. Goulianos, Blois Workshop, Helsinki, Finland


Dijets in double pomeron exchange

(not detected)

Dijets in Double Pomeron Exchange

Test of factorization

R(SD/ND)

equal?

R(DPE/SD)

Factorization breaks down

The second gap is un-suppressed!!!

K. Goulianos, Blois Workshop, Helsinki, Finland


Run ii diffraction at the tevatron

Run II Diffraction at the Tevatron

CDF Forward Detectors

  • MiniPlug calorimeters (3.5<h<5.5)

  • Beam Shower Counters (5.5<h<7.5)

  • Antiproton Roman Pot Spectrometer

K. Goulianos, Low-x Workshop, Nafplion


Run ii forward detector layout

Run II Forward Detector Layout

K. Goulianos, Blois Workshop, Helsinki, Finland


Miniplug run ii data

MiniPlug Run II Data

MiniPlug tower structure

  • ADC counts in MiniPlug towers

  • in a pbar-p event at 1960 GeV.

  • “jet” indicates an energy cluster

  • and may be just a hadron.

  • Approximately 1000 counts = 1 GeV

Multiplicity distribution in SD and ND events

K. Goulianos, Blois Workshop, Helsinki, Finland


Run ii data samples

Run II Data Samples

Triggers

  • Results presented are from ~26 pb-1 of data

  • The Roman Pot tracking system was not operational for these data samples

  • The x of the (anti)proton was determined from calorimeter information:

(-)+ is for (anti)proton

K. Goulianos, Blois Workshop, Helsinki, Finland


Diffractive dijet sample

ND+SD & SD+MB

overlap events

x ~ 1

SD

events

0.03<x<0.1

Flat

region

Diffractive Dijet Sample

K. Goulianos, Blois Workshop, Helsinki, Finland


Diffractive dijet structure function

Diffractive Dijet Structure Function

Ratio of SD to ND dijet event rates

as a function of xBj

compared with Run I data

No x dependence observed within 0.03 < x <0.1

(confirms Run I result)

Ratio of SD to ND dijet eventrates

as a function of xBj

for different values of Q2=ET2

No appreciable Q2 dependence observed

within 100 < Q2 < 1600 GeV

K. Goulianos, Blois Workshop, Helsinki, Finland


Dijets in dpe

Dijets in DPE

In SD data with RP+J5 trigger

select events with rapidity gap

in both the BSC_p and MP_p

(3.5 < h <7.5)

K. Goulianos, Blois Workshop, Helsinki, Finland


Data selection

DPE: RP+J5+BSC_GAP_p

DPE dijet candidates

Prescale=5

SD: RP+J5

Single Diffractive dijet candidates

Prescale=280

ND: J5

Tower with ET > 5 GeV

Data Selection

K. Goulianos, Blois Workshop, Helsinki, Finland


Dpe dijet kinematics

DPE Dijet Kinematics

K. Goulianos, Blois Workshop, Helsinki, Finland


Inclusive exclusive dpe dijet predictions

Inclusive/Exclusive DPE Dijet Predictions

K. Goulianos, Blois Workshop, Helsinki, Finland


Limit on exclusive dpe dijets run i

Limit on Exclusive DPE Dijets (Run I)

  • Observed ~100 DPE dijet events

  • 0.035 < x < 0.095

  • Jet ET > 7 GeV

  • Rapidity gap in 2.4 < h < 5.9

Dijet mass fraction

MJJ based on energy within cone of 0.7

=> look for exclusive dijets in window

0.7 < RJJ < 0.9

K. Goulianos, Blois Workshop, Helsinki, Finland


Run ii exclusive dpe dijets

Run II: Exclusive DPE Dijets ?

No exclusive dijet

bump observed

K. Goulianos, Blois Workshop, Helsinki, Finland


Double pomeron exchange dijet events

Double Pomeron Exchange Dijet Events

Rjj=0.81, Jet1(2)=33.4(31.5) GeV

Rjj=0.36, Jet1(2)=36.2(33.3) GeV

K. Goulianos, Blois Workshop, Helsinki, Finland


Summary

SUMMARY

  • Soft Diffraction

Use the reduced energy cross section

  • Pay a color factor k for each gap

  • Hard Diffraction

Get gap size from renormalized Pgap

Soft and hard conclusions

Hard

SOFT

Diffraction is an interaction between low-x partons subject to color constraints

K. Goulianos, Low-x Workshop, Nafplion


  • Login