Topical Summary of Experimental Results

1
Topical Summary of Experimental Results

Kerstin Borras D E S Y Hamburg

• What to take home from
• inclusive and diffractive e p scattering
• exclusive production processes in ep, pp
• Tevatron and LHC
• spin, nuclei physics ?
• What might the future bring ?

2
Some Statistics
2 talks with 1.25 h on inclusive results 5 talks
with 2.5 h on diffractive results 5 talks with
2.25 h on exclusive results 2 talks with 1.25 h
on spin physics 3 talks with 1.5 h on Tevatron
RHIC 4 talks with 2.25 h on LHC 21 talks with
11h in total (compared to 36 talks with 12.5 h
in theory) ? increased a lot compared to
Diffraction 2004, 2002, 2000 ? now the right
balance for fruitful discussions between
theorists and experimentalists
? means 1-2 slides per presentation, please
consult the original talks for details and
... stay awake and watch out for your slide
3
Thanks

• Before I might be cut off at the end, because I
  want to
• report on too many interesting results
• Thanks to the organizers for giving me the
  opportunity to summarize all these nice results.
• Thanks to all speaker for having me provided with
  their slides in advance, all talks were so well
  prepared, that it was a pleasure to cut and paste
  
• Thanks once more to the organizers for this
  enjoyable workshop !

4
Inclusive DIS _at_ HERA (J.Kretzschmar)

• incredible accuracy achieved

• same statistics for e and e-

• polarization data analysed

• joint ZEUS H1 analysis to
• increase the statistic

5
Inclusive DIS _at_ HERA (J.Kretzschmar)
Higher precision achieved by including jet data
into the QCD fit data sample still differences to
be sorted out between the experiments common
working groups established
6
PDF Uncertainties _at_ Tevatron (A.Robson)
W charge asymmetry ? d / u
1998 30 in d _at_ Q220
7
PDF Uncertainties _at_ Tevatron (V.ODell)
Inclusive jets for the most uncertain pdf high
x-gluon. Main uncertainties jet algorithms
and jet energy scale.
8
Spinning Protons (A.Krisch)
Enjoyable review of polarized proton
scattering starting in the 70-ties and planning
for the future
9
Gluon Polarization (K.Kurek)
10
Exclusive Processes
Vector Meson Production N.Berger (H1), D.Szuba
(ZEUS), A.Borissov (HERMES) R. Fabbri
(HERMES) DVCS, high t photon production
M.Beckingham (H1), R.Fabbri (HERMES) ?
incredible rich physics field
impressive new results with high precision
11
Exclusive Vector Meson Production
Genralized Parton Density Functions
Regge - Ansatz
2-gluon, gluon-ladder
Extraction of the pomeron trajectory
12
Exclusive VM Regge Trajectory
(N.Berger)
in ? in PHP ?IP(t) ? 1.093 0.116 t J/? PHP
?IP(t) ? 1.200 0.115 t J/? in DIS
?IP(t) ? 1.20 0.07 t J/? in PHP, high t
?IP(t) ? 1.15 - 0.02 t

• universal pomeron ?
• appropriate scale, a combination of Q2, M2, t ?

(D.Szuba)
13
Exclusive Vector Meson Production
Genralized Parton Density Functions
Regge - Ansatz
2-gluon, gluon-ladder
Extraction of the pomeron trajectory
Sensitivity to gluon density and parton evolution
14
Exclusive VM 2-gluon BFKL models
(N.Berger)

• access to gluon densities at small x, where
  inclusive DIS provides only poor constrains

15
Exclusive Vector Meson Production
Genralized Parton Density Functions
Regge - Ansatz
2-gluon, gluon-ladder
Extraction of the pomeron trajectory
Sensitivity to gluon density and parton evolution
16
Exclusive VM GPDs from Pion Pairs
Legendre Moment ltP1(cos?)gt interference of
different p p isospin states
R. Fabbri
17
DVCS and high-t Photons
(M.Beckingham)

• DVCS _at_ HERMES (R.Fabbri)
• Transverse Target-Spin Asymmetry
• versus Q2, x and t
• sensitive to H , E
• first model dependent constraint on Ju and Jd

18
Summary of this part

• A lot of accurate data have been taken and
  carefully analyzed
• inclusive DIS _at_ HERA has achieved an
  unprecedented precision for unpolarized and
  polarized measurements with electrons and
  positrons,
• HERA experiments now started common projects to
  decrease the statistical uncertainty even
  further.
• At the Tevatron several analyses have now such
  small statistical and experimental uncertainties,
  that the uncertainty in the pdfs plays a major
  role.
• The experiments use a large variety of processes
  which are sensitive to different pdfs in
  different kinematic regions.
• Exclusive processes at HERA show a large
  sensitivity to the gluon pdfs and to parton
  evolution schemes and interesting results have
  been obtained.

19
Inclusive Diffractive DIS (P.Laycock, H1,
B.Löhr,
ZEUS)
Comparison of new preliminary data for ALL three
analysis methods (LRG,LPS,Mx) for data of the
same running period ? general agreement, details
have to be looked at more closer ? aim for a
consistent picture

• Recently published data
• ? comprehensive study of inclusive
• diffractive DIS !
• Points of debate
• Q2 dependence of ?IP(0)
• (dis-)agreement with Mx method

? homework ? fit for fixed
xIP (Dino)
20
Inclusive Diffractive DIS (B.Löhr)
r 0.22 0.034.ln(1Q2)
Diffractive contribution ranges from 16 down to
2 ? at high Q2 already close to Tevatron ratios.
21
Fits to Diffractive DIS (P.Laycock,M.Mozer)
Now finally published
different ?S ? not easy to compare to the
previous diffractive pdfs
22
Diffractive Dijet Charm Production (M.Mozer,
H1,
I.Korzhavina, ZEUS)
DIS QCD - Factorization is proven for ? pdfs
applicable to other processes PHP Violation of
factorization expected (possibly due to
re-scattering)
23
Leading Baryon Production (L.Rinaldi)
Re-scattering processes expected to lead to
absorptive effects in xL
spectrum and b-slopes.
PHP DIS
Absorptive effects observed between PHP and DIS
and described by model of DAlesio and Pirner
Precise data available, absorption described by
theoretical models ? can derive valuable input
for exclusive Higgs production _at_ LHC
24
Changing the Processes
25
Diffraction at the Tevatron (CDF) (K.Goulianos)
New preliminary results from Run II higher
statistics ? higher Q2
and t-dependence
ETjet 100 GeV !

• Small Q2 dependence in region 100 lt Q2 lt
  10,000 GeV2
• Pomeron evolves as
• the proton!

26
Diffraction at the Tevatron (CDF) (K.Goulianos)
Detailed comparisons for exclusive dijet
production with Monte Carlo
Helpful for adjusting model parameters in
exclusive Higgs production _at_ LHC. Three events
for exclusive ?? production identified. CDF in
the process of completing the background
estimation.
27
Diffraction at the Tevatron (DØ) (V.ODell)

• The new DØ diffractive spectrometers are working
  well and are being understood
• FPD data is recorded in all 9 spectrometers
  (Still effort ongoing in alignment, calibration )
• Diffractive analysis program at DØ is starting to
  take off
• 10 Ph.D. students pursuing diverse analysis
  topics (diffractive Z, W, HF, forward jets, SF,
  DPJets, inclusive DP, exclusive events in
  double pomeron, elastic)

28
Diffraction _at_ RHIC (S.White)
Main detector component Zero Degree Calorimeter

• Total Cross Sections
• RHIC methodology uses calculable EM cross
  sections to calibrate (eg Coulomb Dissociation,
  gd ? np)
• Peripheral g-A interactions
• Diffractive Vector meson production
• gg ? ee-
• Deep inelastic g-A interactions
• -dijet, jetg, Heavy Flavor production
• Other Forward Physics, eg pp ? np

ZDC very successful for RHIC
? proposed a ZDC for ATLAS _at_ LHC
29
Forward Physics _at_ LHC
Presentations F.Ferro TOTEM R.Orava Forward
Physics measurements _at_ LHC C.Royon Forward
Detectors in ATLAS S.White Inelastic Diffraction
with Heavy Ions _at_ RHIC and
LHC R.Croft Experimental Aspects of Central
Exclusive Higgs Production
30
LHC Experiments pT-h coverage
CMS fwd calorimetry up to h ? 5 Castor ZDC
1000
CMS
ATLAS
100
T1
T1
pT (GeV)
ALICE
LHCb
10
T2
T2
1
microstation
microstation
CASTOR
CASTOR
RP
RP
0.1
veto
veto
pTmax ?s exp(-h)
ZDC
ZDC
0
-12
-10
-8
-6
-4
-2
2
4
6
8
10
12
h
The base line LHC experiments will cover the
central rapidity region. TOTEM?CMS will
complement the coverage in the forward region.
fp420m
R. Orava Diffraction 2006 Milos Island
31
Status of TOTEM (F.Ferro)
TOTEM will be ready
for data taking
at the start of LHC
32
Physics Menue _at_ LHC (R.Orava)

• TOTEM
• total pp cross section (and luminosity) with a
  precision of 1
• elastic scattering dsel/dt for 10-3 lt t lt 10
  GeV2
• pp interaction radius (slope in dsel/dt)
• total pp cross section (with the inelastic rate)
  
• Coulomb-nuclear Interference (expected to have an
  effect over large interval in t).
• ratio of the real and imaginary parts (dispersion
  relations ? precise measurement of r will
  constrain stot at substantially higher energies)

• CMS TOTEM (see also forth coming paper)
• single diffractive cross section to 10 ? test
  various models
• diffractive heavy flavor production, t t
  production
• low x measurements via forward jet production
  with veto-counter upgrade down to x ? 10-8 !
• Drell Yan in CASTOR ? x ? 10-7
• Central Diffraction
• Higgs production with various decay channels
• heavy flavor quark systems
• gluon collider ? glueballs hybrids
• Photon - Physics
• SM tets with ?? , ?p and ? N interaction
• luminosity measurement with lepton pairs
• minimum bias events

33
The minimum-bias events should be
understood, too...
(R.Orava)
The minimum-bias energy flows populate the
forward detectors ... while the central
detectors are floded by a large multiplicity of
soft particles...
Underlying events probed by the forward tags.
Underlying event energy has to be subtracted in
all measurements ? quite strong
impact on all results. Underlying event is
closely related to forward physics parton
evolution models, AGK cutting rules, color flow
screening, string length in hadronization ?
see proceedings of the HERA-LHC workshop.
34
Forward Detector _at_ ATLAS (C.Royon,S.White)
35
The FP 420 Project (R.Croft)

• Extend the acceptance for leading proton tagging
• combine information from central detector and RP
  _at_ 220m

CMS/ATLAS
TOTEM / ATLAS RPs
FP420

• CEP offers complementary Higgs production
  
  precision physics at a
  Hadron Collider (Mass, Spin, Parity).
• Trigger
• Latency limits forward trigger information to
  near-beam detectors at 220m for L1, but not HLT.
• Triggering on light H-gtbb_bar (Jet-Jet) tricky,
  but feasible.
• Pile-up Background
• Fast-timing detectors ? leading protons are
  connected to primary vertex of hard-scattering
  process ?
• Provides good control of pile-up produced
  background at high luminosity.
• FP420
• RD fully funded.
• Technical Design Proposal to ATLAS/CMS by
  first-half of 07. If accepted by either / both,
  then to the LHCC.
• Installation 08-09 (1st LHC Long break)?

36
Prospects for the Future

• HERA running fine with occasional problems,
  
• on the way to collect a lot of lumi,
  
• special low energy running for FL measurement,
• HERMES has installed the Recoil Detector (DVCS)

37
Prospects for the Future
Run plan up to 2010 (RHIC II)pp is polarized
beam run
RHIC

• Outlook for COMPASS
• long term project, formally approved until 2010
• running time will be adjusted on a year to year
  basis (? LHC running)

38
LHC

• L.Evans (ICHEP06)
• First beams will be injected into the LHC in
  November 2007 and will be brought into collision
  at 900 GeV (cm) in order to debug the machine and
  the detectors.
• The first high energy run will start in spring
  2008 and continue through the year, when it is
  expected that a few fb-1 will be accumulated.
  Running at nominal luminosity would give around
  80 fb-1 per year.
• The LHC is designed for an ultimate luminosity
  of 2.3x1034cm-2.s-1 without further hardware
  investment and with only two detectors
  illuminated.

• The luminosity could be increased by a further
  factor of two by reducing the beam size at the
  interaction point. As a consequence, the beam
  size in the inner triplet would become
  unacceptably large. The aperture in the inner
  triplet would need to be increased from the
  present 70mm to at least 90mm, increasing the
  field on the conductor by the same amounts.
  Studies are under way on the design of new inner
  triplet quadrupoles.

39
Summary of the Summary
All experiments have considerably improved the
precision of their data. Looking forward to even
more precise data in different kinematic regions
from all various kinds of accelerators and
experiments and of course to first diffractive
events at LHC. A lot of progress has been
achieved so far, but still a lot remains to be
understood ? intensive discussions
between the theorists and experimentalist of the
various fields are vital.
40
Need Discussions Among Each Other
RHIC
SPS
Tevatron
HERA
Next Opportunity XII International Conference on
Elastic and Diffractive Scattering (Blois
Workshop) 21st 25th of
May _at_ D E S Y (prel. date) (Organizers
J.Bartels, K.B., M.Diehl, H.Jung)
LHC
ILC
41
What to take home ?
42
Backup Slides
for more Information
43
Tevatron SD dijets _at_ 1800 GeV

• x1/?s ? ?i ET,i e-?i
• ? (xIP) from RPS
• ? x/ ?

p
IP (? (xIP) ,t)
p
p
RPS
Ratio power law behavior, independent
from (? xIP)
Effective structure function for dijet
production Fjj(x)x g(x) 4/9 ?(q(x)q(x))
Tevatron unfold from ratio
Fjj from proton pdf (HERA use diffractive
pdf and extrapolate xIPlt0.05 ? 0.035lt?lt0.095)
44
Reggeon and pion contributions in diffractive
processes
K. Golec-Biernat, J. Kwiecinski and A. Szczurek,
Phys. Rev. D56 (1997) 3955.
from Aharons talk at last DIS
CDF
Note from KB Expect IR contributions to
dominate in the CDF region, but when folding the
above flux with the hard cross section, where the
dijet production st Tevatron is dominated by
gluons ? the reggeons and pions (containing
mostly quarks) are in the end suppressed in the
CDF diffractive dijets.
45
Tevatron SD dijets _at_ 1800 GeV
FjjD(? ,?) 1/ ?n
and FjjD(? ,?) 1/ ?m
?IP
?IR

• FjjD(? ,?) 1/ ?n independent
  of ? ? no change in
  structure from IP region to IR region
• FjjD(?0.1,?) 1/ ?m m1.0?0.1 for dijets
  ? hard interaction has larger ?IP than soft
  incl. diffraction
• ? dijets are IP dominated,
  soft incl. diffraction more IR like

? p
large IR contribution expected from
0.035lt?lt0.095, but ? dependence more IP like (m
for IP is 1.1, for IR 0 and for Pi -1 at
Tevatron ).
Structure power law behavior Fjj 1/ ?n with
n1.00.1 for ?lt0.5
46
Comparisons Tevatron - HERA
H1 2002 fit Shape now similar for low ß ? same
evolution, but difference at high ß
normalization off by a factor 10 (careful
large uncertainties for CDF 25 and also for
HERA as, initial parameterizations . large IR
contribution, here up to 50 ! ?
47
LPS Comparison with CDF

• No estimate of uncertainties yet
• large at high b (no coverage !)
• result stable at low b
• Smaller discrepancy with respect to
• CDF than suggested by H1 estimate
• CDF data close to Reggeon
• contribution
• does this mean something ?
• Difference with respect to H1
• - a small contribution (10 ?)
• possibly due to proton-dissociative
• background in H1 data.
• - Where does the rest come from ??
• (in particular for the Reggeon part)
• - Different xIPcoverage (LPS up to
• xIP0.07) ?

(LPS)
NO !
48
Diffractive Characteristics compared to HERA
(animated slide)
FjjD(? ,?) 1/ ?n ? 1/ ?m for ? lt 0.5
FjjD(? ,?) 1/ ?m
Although 0.035lt?lt0.095 no large IR contribution
(mIP?1.1, mIR?0, m??-1)
m
Same ? dependence in very old HERA 94 data
ZEUS-Mx, ZEUS-LPS, H1 rap.gap (xIPlt0.05) and CDF
(0.035lt?lt0.095) (See DIS2000 Liverpool) Not
straight forward to explain in particle picture
of pomeron with Regge-fluxes from soft hadron
interactions.
IP ?
IR ?

• Leaving the IP particle picture and going back to
  underlying proton pdf shows the accidential
  agreement
• CDF dijets are gluon-interaction dominated, at
  larger x higher Q2
• HERA DIS more quark-interaction dominated, at
  smaller x medium Q2
• When looking in terms of ?, the gluon and quark
  pdfs have a similar slope in the two relevant
  kinematic regions.
• diffraction is given by the parton behavior in
  the sea at the relevant kinematic values and is
  not to be defined by the value of xIP ? !