DIFFRACTION and Forward Physics

1
DIFFRACTION and Forward Physics2
M. Arneodo, M.Diehl, V.A.Khoze, P.Newman
with a bit of personal flavour
Plan

• 1. New theoretical results presented at the 4th
  Workshop
• 2. Selected hot topics
• survival of
  the survival factor,
• basic
  soft cross-sections at the LHC
  
  
• 3. What can HERA still provide ?
• 4. Selected early LHC measurements to test
  predictions
• for diffractive processes
• Apologies to those excellent enthusiastic
  speakers,
• whose results were not (properly) covered
• 
  (lack of time or / and expertise)

by popular demand
2
Theory Talks
(??-part)
Selection -as seen through the eyes of the needs
of Forward Physics Community
-minimal overlap with other WGs
some overlap SATURATION ? JB
nontrivial task of transferring a theoretical
description of saturation from HERA to the LHC
? K. G-B, GW sensitivity of the
Diffractive DIS to the saturation ?
sat. effects quantified- GW
3
Exclusive Central Production
(10 talks)

• Selection rules mean that central system is 0
  ?pinning down the quantum numbers
• CP violation in the Higgs sector shows up
  directly as azimuthal asymmetries
• Tagging the protons means excellent mass
  resolution ( GeV) irrespective of the decay
  products of the central system. LO QCD
  backgrounds suppressed
• Proton tagging may be the discovery channel in
  certain regions of the MSSM.
• Unique access to a host of interesting QCD
  processes

Very promising addition to the party line
Higgs studies at the LHC and even at the
ILC/CLIC (KMR, J.Ellis et al,
Manchester group )
(gg)CED ? bb
Very schematically exclusive central production
is a glue glue collider where you know the beam
energy of the gluons - source of pure gluon jets
- and central production of any 0 state which
couples strongly to glue is a possibility
4
(P. Bussey, C. Royon)
H
Improved during this Workshop, coming soon
(already a bit outdated)
5
Photon-photon and photon-proton collider _at_ LHC
(P. Bussey, J. Nystrand,M. Strikman)
Process
WWA spectrum

• Extensive Program
• ? ?? ??, ee QED processes
• ? ?? QCD (jets..)
• ? ?? WW anomalous couplings
• ? ?? squark, top pairs
• ? ?? BSM Higgs
• ? ?? Charginos

and ?p
6
LHC as a High Energy ??? Collider
KMR-02
7
(P. Bussey )
?? PHOTOPRODUCTION
Cross sections for various ?? processes. The
dimuon process may be good for LHC luminosity
monitoring. WW- has a large cross section of
100 fb.
8
Recently -renewal of the interest
BAD NEWS
KMR-02
9
Exclusive Channels in pp -collisions
G. Watt, L.Motyka, A.Martin, J.Nystrand
in a peaceful coexistence
exclusive J/? from HERA data as an independent
source of information on unintegr.
gluons, needed for the H-Central Excl. Higgs
Production (TT,GW)
(GW, LM, JN)
Exclusive ? production at the LHC as probe of
unintegrated gluons
(GW, AM)
Give us unintegrated gluons in advance (P.Bussey )
a nice way to search for the Odderon ( LM, AM,
JN) a potential discovery
channel
10
(No Transcript)
11
(L. Motyka, A.Martin)
odderon exch
g exch
(ALICE, LHCb)
(R. Schicker, ?, J/? - RG)
12
G. Watt, L.Motyka (good agreement with J.Nystrand
and KMR )
(blessed)
(J. Pinfold)
13
Selected Hot Topics
conflict of interests
Importance for the Forward Physics Studies at the
LHC Serve as a litmus paper indicator of the
level of our knowledge (theory experiment) on
diffractive physics at high energies
Survival of the Survival Factor
(Regular talks by U. Maor (GLM), A. Martin (KMR)
and M. Strikman (FHSW))
Account for the absorption effects -necessitated
by unitarity
S² -a crucial ingredient of the calculations of
the rate of the Central Excl. Diffractive
processes .. Prospects of New Physics
studies in the Forward Proton mode
qualitatively new stage a delivery of our
meetings orders of magnitude differences in
theoretical expectations are a history







(not so long ago- between Scylla
and Charybdis) new (encouraging) CED
Tevatron results available, more results to come
(K. Goulianos, J. Pinfold) we are discussing
now the differences on the level of a factor of
(4-5) (M. Strikman)
14
(K . Goulianos)
arXiv0712.0604 , PRD to appear soon
A killing blow to the wide range of theoretical
models.
15
PT LO undisputable
16
FHSW
weak (1/2) suppression
(a factor of 4-5 diff. )
(M. Strikman)
it might be much worse
17
Approach to the Black Disc Regime
(how rapid is it above 2 TeV ?)
START at ? 2 TeV
FINISH BDR,
1
1. KMR ? slow (logarithmic) rise
by few at the LHC 2. FHSW ? BDR for
energies ? 2 TeV (soft interactions and hard
dipole-proton int. up to
) 3. GLM(M) ? two components conservative
BDR-like
18
?(tot) , ?(el) , ?(SD)
Bread and butter of TOTEM and ALFA measurements
Importance for various LHC studies ( e.g.
notorious Pile-Up) Low mass SD (DD)- one of the
major current limitations on the models ( still
not sufficient exp. Information)
KMR-07, A. Martin relatively low (about 20
below the standard central value) value of
?(tot) at the LHC

( S.Sapeta and K.
Golec-Biernat-05) , ?(tot) ?90
mb cosmic rays, (early) LHC tests
coming soon inescapable consequence of the
absorptive corrections caused by the higher-mass
excitations (A.Martin)



GLM (arXiv 0805.0418) ?(tot ) 110.5 mb, ?(el)
25.3 mb
?
(GLM)M (arXiv 0805.2799) ?(tot ) 92,1 mb,
?(el) 20.9 mb KMR (A.Martin)
?(tot ) 90.5 mb, ?(el) 20.8 mb
GLM(M)- essential improvement of their
description of the Tevatron elastic and SD data
19
th
20

Selection Criteria for the Models of Soft
Diffraction
We have to be open-eyed when the soft physics is
involved. Theoretical models contain various
assumptions and parameters. Available data on
soft diffraction at high energies are still
fragmentary, especially concerning the (low mass)
diffractive dissociation.
?
?
A viable model should incorporate the
inelastic diffraction SD, DD (for instance
2-3 channel eikonal of KMR or GLM(M)) describe
all the existing experimental data on elastic
scattering and SD ,DD and CED at the Tevatron
energies and below (A. Martin GLM(M),
0805.2799 ) be able to explain the existing CDF
data on the HERA-Tevatron factorization breaking
and on the CED production of the di-jets,
di-photons, ?, J/?, ?.., lead. neutr. at
HERA provide testable pre-dictions or at least
post-dictions for the Tevatron and HERA So
far KMR model has passed these tests.
Only a large enough data set would impose the
restriction order on the theoretical models and
to create a full confidence in the
determination of S².
Program of Early LHC
measurements (KMR, A. Martin)
LET THE DATA TALK !
21
What can HERA still
provide ?
(From DIS08)
test higher twists
t- depencences (VM, (V)FPS) Odderon
searches
22
More detailed data on proton dissociation in
diffractive J/? production (better statistics,
M²-slicing).
Improved statistics on exclusive ?- production
(not sufficient at the moment).
The ratio of diffractive to exclusive dijets,
photo to electroproduction.
Transverse momentum distribution of secondaries
in the Pomeron fragmentation.
23
The Extraction of the Bare Triple-Pomeron Vertex
Existing (ZEUS) data on J/? -still fragmentary
Needed - improved statistics
-distributions over M²Y
-inelast. diffractive ? data small size-
component
(small rescatter. effects)
(dress code)

• a crucial ingredient for understanding
  diffraction (e.g. S² calc.)

? Bare
?
A way to extract the information on
?
?
KMR-06
(by integration over ZEUS range)
(after acconting for the second.
traject.)
?0.2
(A. Martin)
?
Importance of an explicit measurement of the
Y-system mass spectrum. To perform a full
triple-Regge analysis with different
contributions quantified.
24
(No Transcript)
25
(A. Martin)
Are the early LHC runs, without proton
taggers, able to check estimates for pp ?
pAp ?
gap
gap
KMR 0802.0177
Possible checks of
(i) survival factor S2 Wgaps,
Zgaps
(ii) generalised gluon fg gp ?Up
Divide et Impera
(iii) Sudakov factor T 3 central
jets
(iv) soft-hard factorisation
(Agap) evts (enhanced
absorptive corrn) (inclusive A) evts

with A W, dijet, U
26
LHC with 220m and 420m Forward Taggers
High sensitivity to the parameters of models for
Soft Diffraction
y-ln ?, ?(1-x)
TOTEM, ALFA, ALICE (RG) ?
27
(No Transcript)
28
Backup
29
(M.Strikman)
30
Watt
S2 0.02
(A. Martin)
31
Exposing the contribution of the Perturbative
Pomeron to DDIS
(G. Watt, A.Martin and M. Ryskin (2006))
The perturbative .resolved Pomeron contribution.
Nonperturbative resolved Pomeron.
Measurements of the kt of secondaries in the
Pomeron fragmentation (edge of LRG). The kt
distribution of the lowest jet should obey the
power law in marked contrast with the
expectations based on Regge-factorization. Large
r kt of the secondaries with the long power-like
tail should be observed.
32
(No Transcript)
33
(No Transcript)
34
P. Bussey
Very promising addition to the party line
Higgs studies at the LHC and even at the
ILC/CLIC (KMR, J.Ellis et al,
Manchester )
H
Improved during this Workshop, coming (very)
soon