Summary of WG B contributions at DIS03 ElectroWeak and Physics Beyond the SM Convenor: Wilfried Buchm

1
Summary of WG B contributions at
DIS03ElectroWeak and Physics Beyond the
SMConvenor Wilfried Buchmüller (DESY), Stefan
Schlenstedt (DESY Zeuthen)

• Electroweak Physics and Top Production
  (three talks)
• Physics Beyond the Standard Model
  (18 talks)
• SUSY, LeptoQuarks, Contact Interactions, Extra
  Dimensions
• Search for Excited Fermions
• Excess of isolated leptons and search for
  unusual events
• Limits on Single Top production

2
ElectroWeak Physics

• over 1000 measurements can be presented as 20
  pseudo-observables (talks by A Mehta, G Altarelli
  and recent reviews)
• on the Z pole line shape, asymmetries, charm-
  and beauty-production
• and W mass and width, top-production, ?N-cross
  section (translated into sin2?W or MW ), Atomic
  parity-violation
• collected at LEP I/II ,
  Tevatron
• and , HERA
  (see WG A)

3
ElectroWeak physics at LEP II
Many precise measurements up to vs209 GeV

• Branching ratios and cross sections
• new measurements of the W-mass at threshold and
  at high energies
• and the W-width
• the triple charged and neutral gauge couplings
  (ZWW, ZZZ, ZZ? )

Talk by J Wilson
4
ElectroWeak physics at LEP II contd
Measure directly the triple-boson vertex
threshold measurement
Talk by J Wilson
5
ElectroWeak physics at LEP II
and lepton universality and ? the global SM fit
Talk by J Wilson
6
ElectroWeak results from Tevatron Run I
W
?(?2) Theory
Z
Talk by A Stone
Top cross section (pb) (based on 100 evts)
7
Tevatron Run II

• Higher beam energy
• new detectors and trigger
• CDF and D0 took 100 pb-1, presented analyses of
  3090 pb-1
• detector commissioning and physics analysis hand
  in hand
• in 0304 less integrated luminosity but improved
  detector acceptances

Talks by A Stone and T Nelson
8
ElectroWeak Results from CDF
combined e, ?, ?
sW ? B(W? l?) 2640 12 93 158lum pb sZ ?
B(Z? ll) 251.5 4.3 10.6 15.1lum pb
?tt (pb)
measured ?W? ? B(W ? e?,??), ?Z?
Talk by T Nelson
9
D0 EW Results

• Four new W Z cross section measurements

?(W) B(W???) 3226128100323lum pb
?(W) B(W?e?) 3054100 86305lum pb
?(Z) B(Z???) 264 7 17 26lum pb
?(Z) B(Z?ee) 294 11 8 29lum pb

• Combining the observation of the top decay
  channels an excess of 3s is observed, compatible
  with a signal expectation at the 35 CL

0
40
?tt (pb)
?
Talk by A Stone
10
ElectroWeak summary
Because of two 3 sigma anomalies, the Standard
Model (SM) fit of the precision electroweak data
has a poor confidence level, CL 0.02. The
data then favor new physics whether the anomalous
measurements are excluded from the fit or notand
the Higgs boson mass cannot be predicted until
the new physics is understood. M Chanowitz, hep
0304199

• AFB(b) and NuTeV 3 ? effects
• Just a regular statistical pattern?
• QCD effects (s, c, isospin)?

11
NNLO for EW, Higgs and SUSY processes

• Calculation of cross sections in pQCD
  factorization of calculable hard short-distance
  and soft long-distance physics, the latter with
  virtual corrections
• A unified approach and a master formula to
  calculate in NNLO the soft and virtual functions
  for processes like hadron-hadron- (Drell-Yan),
  lepton-hadron-scattering, total xsecs, SM and
  charged Higgs production, FCNC single top
  production, SUSY
• Example FCNC single top production at HERA eu ?
  et

at vs 300
Talk by N Kidonakis
12
Phenomenology of a SU(2) Triplet Higgs

• Extension of the SM Higgs sector add a real
  triplet to the complex doublet (unlike the MSSM
  with a second doublet)
• investigate if the then SM Higgs can be heavy
  and what the relation to the new Higgs masses is

500

• checked if the Quantum- corrections are changing
  the picture ( ? no)

100
Talk by A Sabio-Vera
500
100
13
Double charged Higgs at LEP
Predicted by LR super symmetric model (Higgs
triplet)
Decay in two charged leptons, mainly in taus.
Yukawa coupling to lepton is free parameter.
h??gt10-7 look for 4 ?s close to interaction
point h??lt10-7 search for kick of charged
tracks h??lt10-8 search for anomalous ionisation
Talk by A Tilquin
14
Doubly Charged Higgs at CDF

• Same sign dielectron data analyzed
• Selection High ET inclusive electron trigger
• Search in mass windows of 10 MH (3?)
• Signal 0 observed
• Control Region Zmass 0 observed
• (0.60.5-0.1 predicted)

Any model with Higgs triplets predicts double
charged Higgs.
Reach sensitivity up to 125 GeV/ c 2 by Summer
(see also H from H1 later)
Talk by A Munar
15
Slepton searches at LEP
2 acoplanar leptons missing energy Main
background from WW?l?l?
Channel ?10 mass Mass limit
Selectron 0 GeV 40 GeV 99.6 GeV 99.4 GeV
Smuon 0 GeV 40 GeV 94.9 GeV 96.5 GeV
stau 0 GeV 40 GeV 85.0 GeV 91.7 GeV
Talk by A Tilquin
16
Search for Neutralino at LEP
Chargino, neutralino slepton and Higgs results
are combined.
LSP mass limit obtained at high tan(?)
Talk by A Tilquin
17
Search for resonant squarks in H1
94-97 data H1, EPJC20 (2001) 639.
Here 99-00 e p data, L 63 pb-1
Look for the signal in all possible decay
modes

1. Rp-violating decay q ? e q
(mainly at large ? )

• High ET e jet

(similar to scalar LeptoQuark )
i.e. look for signal in high ET/ Q2 NC DIS


2. Gauge decays q ? q ?i0 or q ?i or q
g followed by cascade decay of gaugino
?L 2
All decays involving at most 2 gauginos are
considered

• e multi-jets NC DIS
• e- multi-jets ? bckgd free
• ? multi-jets CC DIS
• e (?) l multi-jets small SM bckgd

(Majorana)
Large number of final states ! BRs depend on
model parameters
18
Constraints in the MSSM sector from H1
example for j1,2
Consider first an unconstrained model
sfermion gaugino sectors are not
related, i.e. M f are free parameters

0.3
Scan of the SUSY parameter space M2, ?, tan?

• Limits on ? 1j1 do not depend strongly
• on the MSSM parameters

• For ? 0.3 ( ?2 / 4? ? em)
• squarks can be ruled out up to ? 280 GeV

• HERAs sensitivity extends beyond the indirect
  limits from low energy experiments for cL (also
  for tL)

weakest
strongest
Talk by E Perez
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Constraints on mSUGRA model ?111,121 from H1

• Sfermion gaugino masses related via RGE
• m0 (m1/2) common mass param for scalar
  (gauginos) at GUT scale
• Assume Radiative Electroweak Symmetry Breaking

5 parameters
m0, m1/2, tan?, sgn(?), A0
tan ? 2
tan ? 6
? 1j1 0.3
m1/2 (GeV)
m1/2 (GeV)
(pair prod, sfermion ?)
100
100
? 1j1 0.3

0
0
150
0
150
0
m0 (GeV)
m0 (GeV)
For medium tan? H1s sensitivity extends beyond
the domain excluded by D0 ? Complementarity.
However H1 bounds depend on ?, D0s do not.
Talk by H Dreiner
In such constrained models LEPII has highest
sensitivity
Talk by E Perez
20
Constraints on mSUGRA ?131 from H1
the stop
?131 would allow resonant stop production at
HERA. Interesting since the stop might be the
lightest squark !
tan ? 10
Larger part of the parameter space is covered
(compared to the case ?1j1, j ? 3)
m1/2 (GeV)
?131 0.3
For intermediate m0, excluded domain not ruled
out by LEPII

100
Sensitivity to M(t1,L) up to ? 270 GeV
?01 lt 30 GeV, i.e. loose t ? b ?1
? b?01XX
sensitivity via RpV decay only
NB Tevatron RunI different frameworks,
but typical sensitivities ? 130 GeV.
RunII ? 200-250 GeV
?1 lt 30 GeV, loose t ? b ?1
0
Discovery potential for RpV stop at HERA with
larger L !
100
200
0
m0 (GeV)
Talk by E Perez
21
Resonance search in the CDF-dijet Spectrum
Event Selection Inclusive Jet Sample (75 pb-1),
two Highest ET jets Fit the Mass Spectrum with
a smooth background
No evidence of resonances

• Limits on Axigluons, Excited Quarks, Octet
  Technirhos , E6 Diquarks, W
• already improved with respect run I

Talk by A Munar
22
LeptoQuarks at Tevatron
LQ
LQs appear in extended gauge sectors and
composite models, scalar and vector particles,
coupling ? to u or d
decay and search strategy LQ ? e (?)q, ?q with
? ? Branching Ratio (LQ ? l q)
LQ
and qq ?LQ LQ
already strong limits from run I
for all three generations
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LeptoQuarks at D0
1st Gen LQ 2 e 2 jets
2nd Gen 2 ? 2 jets
MLQ gt 179 GeV
Theoretical NLO ? (for Q 1, 0.5, 2 ? MLQ)
MLQ gt 157 GeV
L 43.0 pb-1
L 30.0 pb-1
? limit at 95 CL
MLQ gt 225 GeV (L 115 pb-1)
MLQ gt 200 GeV (L 120 pb-1)
Run I
Talks by O Kouznetsov
24
LeptoQuarks at CDF (1rst Gen)
2 high ET electrons and 2 jets
Missing Energy and 2 jets
M(LQ) gt 230 GeV/c2 _at_ 95 CL (Run I 220 GeV/c2 )
M(LQ) lt 60 GeV/c2 or M(LQ) gt 107 GeV/c2 _at_ 95 CL

• Limit already better than Run I
• 25 increase in the cross section
• factor 1/3 less luminosity
• acceptances slightly higher

• ( not searched in Run I by CDF)
• Limit from D0 (Run I, similar luminosity) M(LQ)
  gt 98 GeV/c2 _at_ 95 CL

Talk by A Munar
25
LeptoQuarks at H1
direct search of resonant LQ production in NC
mass spectrum no excess ? limits
e- sensitive to F3BL2
99-00 data
above vs318 u- and s-channel contribution
Talk by J Scheins
26
LeptoQuarks at ZEUS
Combine channels with eq and ?q when possible
Constant ? for scalar LQ as function of
branching ratios ? into eq and ?q
Talk by G Barbagli
27
LeptoQuarks at LEP
New color triplets bosonic fields mediating
interaction between quark and leptons
Spin Q F ?l
Scalar Vector ?1/3,?2/3 ?4/3,?5/3 0,2 0,1/2,1
Talk by A Tilquin
28
Contact Interaction at HERA
parametrize the deviation from SM through
four-fermion contact interaction with an
effective coupling g2/?2 for different chiral
combinations
Limits for effectice mass scale ?eeqq 1.7 7.0
TeV
All models are consistent with the SM
Talks by J Scheins and G Barbagli
29
Extra dimensions at LEP
Trying to solve the hierarchy problem Weakness
of Gravity at electroweak scale

• Our word confined to four dimensions
• Gravity propagates in extra dimensions (ADD)

By choosing MD??EW?No hierarchy problem
Small but large number of states (GKK)
1/MPl
d1 ?R1013 m Excluded d2 ?R1 mm d3 ?R1
nm . d7 ?R1 fm Max in M-theory
f,V
G
f,V
Talk by A Tilquin
30
Extra dimensions at LEP (cont)
Direct search missing energy
LEP average MSgt1.2 TeV (?1) MSgt1.09TeV
(?-1)
Indirect look for deviation from (d?/d?)SM
Talk by A Tilquin
31
Search for Extra Dimensions at D0
Fit the distributions in the Mll - cos? plane
to determine the value of hG di-e hG 0.00.27
TeV-4, di-? hG 0.021.35 TeV-4 ( hG 0 in
SM) Extract 95 CL upper limits on hG ?translate
to 95 CL lower limits on Planck scale MS
Di-e limit close to Run I, Di- ? (new)
Talk by O Kouznetsov
32
Search for Extra Dimensions at HERA
Search again for deviations in the Q2 distribution
MSgt (TeV) H1 ZEUS
? -1 0.78 0.82
? 1 0.82 0.81
Talks by J Scheins and G Barbagli
33
Excited Fermions Composite models to explain the
number of families
Talk by M Schneider
34
Excited Fermions at HERA
Neutrino?
Electron?
Quarks?
gt HERA superior at high s (LEP) gt more sensitive
at small fs (FNAL)
Talk by M Schneider
35
Excited fermions at LEP
In composite models, fermion boson are
composite with and associated energy scale ?.
gauge group weights factor
Lot of decay channel at LEP
From differential x-section
Talk by A Tilquin
36
Excited Fermions at CDF
Search
0 events observed

• Limits on Me? and ??BR(e?e? )
• Me? ?, Me? lt 785 GeV/c2
• compare to current Limit ( H1 )
• Me? ? Me? lt 223 GeV/c2

Talk by A Munar
37
Inclusive Searches in DiPhoton Signature at CDF
Search for Diphoton extra leptons 0 events
found (in agreement w SM)
? Limits on Gauge Mediated Supersymmetry
Observed 2 Expected Events 2 ? 2

• MC gt 113 GeV/c2 _at_ 95 C.L.

Talk by A Munar
38
Unusual events at HERA
39
Isolated e and ? at HERA with large missing pT
Talk by G Frising
Confirmation of excess H1 in e data no excess in
H1 e and ZEUS e
Backgrounds well understood largest SM
contribution W production (hadronic channel
checked as well)
W production calculated in NLO (two independent
calculations) correction 10-15 w
reduced scale uncertainty - not the source of the
H1 excess Talk by C
Schwanenberger
Excess at large pT and MT where the SM
contribution is small
40
Unusual events at HERA
41
Isolated ? at ZEUS with large missing pT
Talk by D Lelas
42
Multileptons at HERA

• di-? cross section (H1) and events (ZEUS) OK
• di-e cross section (H1) and events (ZEUS) OK
• H1 observes excess at high masses M12gt100 3/3
  
• (for 2/3 e) and expects .25/.23
• ZEUS observes 2/0 (for 2/3 e) and expects 1.2/0.4

at high pT mainly ??
Understand this SM process, e.g. as BG to
isolated leptons and for the
exclusion plot on coupling hee
Search for Higgs (coupling to di-lepton) as
source for excess ? too small ? set limits
Talk by A Parenti
43
Single Top production at HERA
e
e

• physics explanation of the lepton excess could be
  anomalous top production in FCNC (see Fritsch and
  Holtmann 1999) - the SM cross section is small 1
  pb
• Search for isolated electron or muon with a high
  missing pT (from the ?)
• Search for 3 jets (two from W)
• reconstruct the top mass
• main Background is SM W production
• no excess found set 95 CL limit on ?(ep?etX)
  and the tu? magnetic coupling limit ??

W
?
t
u,c
b
p
W ? lep or had
??
H1 ZEUS
? (pb) lt 0.43 pb 0.23 pb
?? lt 0.22 0.17
Talks by A Schöning and D Dannheim
(status of ICHEP02)
44
Talk by D Dannheim
45
Anomalous t-coupling and SUSY at LEP
R-parity violation
Talk by A Tilquin
46
Summary

• LEP1/2 and Tevatron run I and HERA I data sets
  analyzed
• Tevatron run II preliminary results, HERA II will
  start
• Electroweak Standard Model sector well measured
  and understood we need more top and of course
  the Higgs
• One expects Physics Beyond the SM at ?(1/?GF)
  300 GeV
• A wide search program showed no signal yet
• A few interesting event classes need confirmation
  at high luminosities at FNAL and DESY

Many thanks to the speakers and the local help