Download Searches for NP : non-SUSY scenarios

Thirteenth International Conference on Supersymmetry
and Unification of Fundamental Interactions
Searches for New Phenomena :
non-SUSY scenarios
Emmanuelle PEREZ
DESY & CEA-Saclay, DSM / DAPNIA / Spp
• Searches in well-known final states :
• indirect effects
• resonances
• Searches in rare SM final states
• Funny experimental signatures…
SUSY ’05, Durham
1
23 July 2005
Searches for New Physics : why & where
Mechanism of the EW symmetry breaking ?
 Higgs (i.e. fundamental scalar) ? Find it…
 structure of the Higgs sector ?
 solution of the hierarchy problem ? SUSY  MPl ? “Little Higgs”   10 TeV ?
extra dimensions  no hierarchy ?
 no Higgs ? Dynamical breaking ? ( H ~ condensate )
extra-dim physics ? ( H ~ Gauge Field|4d )
In most scenarios, new physics is expected at the TeV scale.
Also hoped for, that NP might answer some of the questions unexplained by the
SM or by SM+SUSY (e.g. quantization of EM charge, particle masses etc)
Various strategies to track new physics, e.g. :
- high precision measurements ( need good theoretical control )
- rare decays (K & B) , LFV processes
- searches at high energy colliders  LEP, Tevatron, HERA
Some complementarities between these different approaches and between
measurements at the three high energy colliders.
E. Perez
2
SUSY’ 05, 23 / 07 / 05
Good performances of our facilities !
_
Tevatron pp, s = 1.96 TeV CDF & D0
Run I (92-96) :  110 pb-1 / exp
Run II (since 01)   1 fb-1 delivered
HERA
ep, s = 320 GeV
H1 &
ZEUS
until summer 2000 :  120 pb-1 / exp
(mainly e+ p)
1000 !
2005
2003-04
Analyses presented here  200-450 pb-1
of Run II data (2002 - 2004)
HERA-II
sample >
HERA-I
HERA I+II analyses : up to  200 pb-1
+ LEP data ! Very relevant constraints on NP ! some final combinations are still to come
+ B-factories : BaBar and Belle collected 350 millions of BB pairs !
E. Perez
3
SUSY’ 05, 23 / 07 / 05
Some news from the Standard Model…
• sin2W at NuTev ? Differs by  3  from global SM analysis
Not clear… theoretical uncertainty ? e.g. asymmetry in s-s, violaton of
isospin in parton distributions due to QED effects ?
?
• (g-2) ? Very precise measurement at BNL (0.5 ppm !)
Above the SM value (2.7 ) if low energy e+e- data are used for aHAD
- e+e-  4 at BaBar using ISR photons : somehow in-between e+e- & 
- (e+e-  ) by KLOE at DANE (s  1 GeV) : confirms the other e+e- meas. …
KLOE, hep-ex/0407048
Burkhardt & Pietrzyk, hep-ph/0506323
• New value of Vus : New measurements from
KTeV and KLOE  unitarity restored !
• sin(2) from b  s penguins :
WA. from charmonium modes went down (LP’05)
Discrepancies seem to get smaller …
E. Perez
• Still discrepancies in polarisation data in
B decays into vector meson when penguins are
involved… could be explained by final state
interactions ? Belle, PRL 94 (2005) 221804
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SUSY’ 05, 23 / 07 / 05
Our backgrounds for NP searches at colliders
NC(Q2>400GeV2) ~ 1000 pb
CC(Q2>400GeV2) ~ 25 pb
Blue = not yet
observed
NC
Tevatron
tt
HERA
Single top
CC
Wbb
Q2 (GeV2)
WZlll
LEP
In this talk :
From well-known
processes to
rare & very rare
processes
WZ+ZZl,ll,llll,ll
E. Perez
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SUSY’ 05, 23 / 07 / 05
d / (d)SM
A lot to learn from “bread & butter” @ colliders
First simple example :
E.g. DIS as the golden process to study the structure
of matter : (at HERA, Q2max  105 GeV2)
Rq < 10-18 m
assign a finite size to the EW charge distributions.
f(Q ) = 1 2
< r2 >
6
2
Q
2nd “generic” example : assume
Q2 (GeV2) that the scale  of NP is large,
parameterize the effects of
NP as a four-fermion
interaction :
_
_
e ,q 4

( ei  ei )( qj  qj )
L=

i, j

i , j = L,R

Typical bounds  > 5 – 20 TeV
Next slides : examples of model-dependent constraints
E. Perez
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SUSY’ 05, 23 / 07 / 05
Dileptons, , DIS & Extra Dim. Scenarios
Interference of KK exchange with SM processes (ee, , , DIS)
• Large extra-dim (AADD) : tower of gravitons G(k)
q
q
, Z
l
G(k)
l
- ee &  at LEP : MS > 1.34 TeV
- DIS at HERA : MS > 0.82 TeV
DY,
QCD “fake”

DY
D0 Run II + Run I,
ee &  :
MS > 1.43 TeV
D0 Run II Prelim, 200 pb-1
SM
SM + signal,
Mc = 500 GeV
E. Perez
ee
Most stringent collider bound:
Tevatron 2 fb-1 : MS up to  2 TeV
QCD
bckgd

At high mass :
e.g. ll,  at
Tevatron :
Effective coupling : A   / MS4
(not a direct probe of MD)
D0, hep-ex/0506063
Negative
interference
• Gauge bosons in “internal” extra-dim :
MC = 1/R// ~ mass of V(1)
qq  , Z, (1), Z(1)  ee
LEP & low energy  Mc > a few TeV
Mc > 1.12 TeV
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First dedicated search
at a collider
SUSY’ 05, 23 / 07 / 05
Examples of dilepton resonances
• New heavy gauge boson Z ’, e.g. models with L-R symmetry or E6 GUT inspired
• (Color-singlet) technirho in Technicolor models
• Kaluza-Klein gravitons in some extra-dim. models
q
_
q
cotan 
• ZH
- Intrinsic width of new particles usually small
compared to the detector resolution
- At high mass acceptances do not depend too much
on the spin (typically ~ 50% for ee)
“Little
Higgs”
CDF II Prelim, 200 pb-1
D0/CDF,

from Mll and 
~ 200 pb-1 
Z’H  ee
E. Perez
above
600
GeV
Still
good
agreement
with SM
in 450 pb-1
First constraints
(direct) on “Little
Higgs” models !
(although “minimal” models predict
heavier ZH, 2-6 TeV)
BR(e) < ~ 30 fb from ee
X BR() < ~ 40-80 fb from 
X BR() < ~ 1 pb from 
X
~ 100 evts
above
200 GeV
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SUSY’ 05, 23 / 07 / 05
Recent Z’ searches
Limits & sensitivities on Z ’ bosons often expressed in :
• SSM : Z ’ couples to fermions like the SM Z
CDF Prelim, 450 pb-1, e+e• E6 inspired models :
Z ’ = Z sin6 + Z cos6
• Recent Tevatron searches
for Z’ use both Mee and cos(*)
(cf LEP sensitivity via AFB)
E6 Z’ models
Adding cos(*)  to 25% more L !
M(Z’SSM) > 845 GeV
(LEP : 1.8 TeV)
 X BR(e) < 30 fb @ 800 GeV
APV
E6 models : direct bounds from Tevatron better
than the indirect LEP bounds Indirect bounds from LEP
much more model dependent
• New models tested, beyond E6
M. Carena et al,
PRD70 (2004) 093009
- Relax GUT relations for gZ’
- Classify models according to the U(1)’ charges of fermions :
E. Perez
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SUSY’ 05, 23 / 07 / 05
Dilepton & diboson resonances : RS gravitons
“Localized gravity” on a “brane” at d  0 from our brane; propagation of gravity
in the extra dim is exponentially damped due to the (tuned) space-time metric
PRL 83 (1999) 3370;
Randall & Sundrum models; “usual” version : n=1, Rc  Planck length
Graviton propagate in extra dim  Kaluza-Klein modes
In localized gravity :
Spin 2
resonance
First direct
constraints
on Randall-Sundrum
models !
G(k) heavy, G(1)  TeV
Coupling of G(k) to SM fields  TeV
Coupling k/MPl
(determined by some model param, k/MPl  0.1)
 brings a large
sensitivity to RS
gravitons since
large branching
PRL 83 (1999) 4690
785 GeV
D0 (, ee, ) :
for M > 500 GeV,
 X BR() < 18 fb
E. Perez
Main bckgs in  :
D0, hep-ex/0505018
0
- jets  
- genuine , dominates at high masses 10
(1) mass
05, 23 /(GeV)
07 / 05
GSUSY’
Z from a long-lived particle ?
Look at the Z resonance itself… but in events where the Z decay vertex
is displaced, e.g. in Z  
Use of the silicon devices to measure the transverse
dca of tracks; apply tight track quality criteria.
Could come from a 4th
generation b’ :
If m(b’) < m(top) :
b’  bZ via loop decay
Acceptance depends mainly on c(b’)
Complements earlier searches :
- b’  bZ, negligible lifetime, b-tag
- low mass b’ via FCNC (b’  b, bg)
Analysis not optimised for the b’ hypothesis
i.e. constraints are quite model-independent.
E. Perez
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SUSY’ 05, 23 / 07 / 05
W  l, DIS and new W’ bosons
q
_
q
WR
e,
e
R
q
WR
R
q’
s-channel W production at Tevatron
and t-channel exchange in DIS at HERA :
very clean experimental signatures
 Look for new W’ boson, e.g. WR
Same signature as W exchanged provided that R is light and stable
• Tevatron : ET and ET thresholds ~ 25 GeV,  ~ 45%
Likelihood fit of the MT distribution :
*BR(W’  e) < 50 – 100 fb for M > 500 GeV
For gL = gR :
M(W’) > 788 GeV
e-
e+
E. Perez
• HERA : polarised eL,R
beam since 2003
CC(e,SM) ~ (1  Pe)
Extrapolations to Pe =  1 consistent with no WR
(not competitive with Tevatron bounds, but
nice “textbook” plot !)
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SUSY’ 05, 23 / 07 / 05
DIS, Zjj, Wjj: Leptoquarks
Apparent symmetry between the lepton & quark sectors ?
Exact cancellation of QED triangular anomaly ?
• LQs appear in many extensions of SM
• Scalar or Vector color triplet bosons
• Carry both L and B, frac. em. charge
LQ decays into (lq) or (q) :
HERA
 (unknown) Yukawa coupling l-q-LQ
TEVATRON
eq
q
llqq
lqq
qq
NC DIS
CC DIS
Z/DY + jj
QCD
W + jj
W/Z + jj
QCD
ZEUS, PRD 68 (2003) 052004
NC DIS
E. Perez
ee
13
• HERA : resonant peak, ang. distr.
• Tevatron : highest ET events
PRD 71, 071104 (2005)
Z/DY+jets
05, 23(GeV)
/ 07 / 05
ST = ETe1 + ETe2+ SUSY’
ETjets
Existing Bounds on 1st Generation LQs
 = BR( LQ  eq )
e
1
1
0.5
0.5
0
Run II bounds
D0
241
CDF
235
208
D0 (ejj)
176
CDF (ejj)
CDF
117
For
 = 4  em  0.3 :
HERA rules out
LQ masses
<  290 GeV @ 95 % CL
 = BR (LQ  eq)
D0 Run II + D0 Run I : M > 256 GeV for =1
=1
H1, hep-ex/0506044
D0, PRD 71, 071104 (2005)
CDF, hep-ex/0506074
• Tevatron probes large masses for large
 (LQ  eq) independently of 
• HERA better probes LQs with small 
provided that  not too small
 Complementarity of both facilities
NB : at HERA, e+ / e- + polarisation could
help in disentangling the LQ quantum nbs
E. Perez
MLQ (GeV)
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SUSY’ 05, 23 / 07 / 05
Second and Third Generation Leptoquarks
So far, LQ2,3 with M > 100 GeV can be probed  exclusively at the Tevatron !
• Search for LQ2 in Run II data :
 + at least 2 jets : bckgd = only DY+jets
~ no bckgd at the end while  ~ 20%
• Search for LQ3  b :
one   e or , the other  had.
Same analysis as RPV stop  b
Total acceptance ~ a few %
D0 Prelim., 300 pb-1
SM bckgd
 DY + jets
M > 129 GeV
… New physics might couple
mainly to 3rd gene fermions
Combined with MLQ > 251 GeV
for  = 1
D0 Run I :
E. Perez
15
More sensitivity expected by
using b-tagging techniques
SUSY’ 05, 23 / 07 / 05
Searches in radiative processes
•  + E at LEP sets strong constraints on large
extra-dim (ADD) : (also branons)
Coupling of G(k) to SM fields
 1 / MPl  G(k) stable !
May be copiously produced
n=2 : MD > 1.5 TeV
n=4 : MD > 0.9 TeV
1 / MPl
compensated by huge
multiplicity of states
CDF, PRL 94 (2005) 101802
• Searches for singly produced excited fermions,
e.g. e*  e , search for a (e) resonance
- Z/DY +  at Tevatron
q , Z
e
- radiative Bhabha at LEP
- radiative DIS, QED Compton q
e*
at HERA
For f/ = 1/M(e*) :
E. Perez
 M(e*) > 250 GeV
16
LEP & HERA : all decay
modes considered
SUSY’ 05, 23 / 07 / 05
Multilepton events at HERA
Events with  2 leptons in final state. Mainly produced via 
Cross-section when both leptons are central,
PT1 > 10 GeV, PT2 > 5 GeV : ~ 0.6 pb
H1 data 94-00 : excess of 2e+3e events at
high M12 = mass of two highest PT e
No such excess seen in ZEUS HERA-I data
The H1 evts are not consistent with
e  H++ (e)  ee(e)
209 pb-1
H1 ( 115 pb-1)
2e, M12 > 100 GeV
3 / 0.30  0.04
3e, M12 > 100 GeV
3 / 0.23  0.04
H1, EPJ C31 (2003) 17
(H1 prelim.)
H1 Prelim.,
HERA I+II
obs. / exp.
H1 94-00 data
expt
selection
H1 analysis extended to include 03-05 data
Extended to other 2l & 3l topologies :
Now ee, , e, eee, e are considered
• no new 2e / 3e evt at M12 > 100 GeV
(but one high mass 3e event …)
• one e evt at M > 100 GeV, one at Me > 100 GeV
2l + 3l
E. Perez
E. Perez
Altogether, at PT > 100 GeV :
Nobs = 4, Nexp = 0.81  0.14
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SUSY’ 05, 23 / 07 / 05
W Production at HERA
Main SM contribution for single W production at HERA :
HERA I : excess (H1) of observed evts
at high PTX w.r.t. SM expectation
PTX
H1,
PLB 561
(2003)
241
(W prod)
 1 pb
e p  l + jet + PT,miss
H1 prelim 94-05, ep, 211 pb-1
H1 ep data,
118 pb-1
Combined e & 
PTX > 25 GeV
11 / 3.4  0.6
Such evts are still observed in HERA II H1 data…
PTX > 25 GeV
e channel
 channel
Combined e & 
H1 94-05
211 pb-1
11 / 3.2  0.6
6 / 3.2  0.6
17 / 6.4  1.1
ZEUS 99-05
106 pb-1
1 / 1.5  0.18
But still do not show up
in ZEUS data…
• no new  evt in H1 HERA II data
• new ZEUS analysis : close to H1 cuts
• ZEUS & H1 expectations agree…
• no significant excess in H1 e-p data (53 pb-1)
E. Perez
18
SUSY’ 05, 23 / 07 / 05
HERA events with isolated lepton + PT,miss
H1 Preliminary, 211 pb-1
obs. / exp.
PTX > 25 GeV
e channel
 channel
Combined e & 
Electrons, 98-05
53 pb-1
2 / 0.9  0.2
0 / 0.9  0.2
2 / 1.8  0.3
Positrons, 94-04
158 pb-1
9 / 2.3  0.4
6 / 2.3  0.4
15 / 4.6  0.8
A “leptoquark-like”
interaction, e.g. RpV
SUSY e+ d  stop ?
(was not supported by
HERA-I data alone)
Wait for more e- data…
• Non SM W production in e ? Most likely smthg should have been seen at LEP…
• New physics in q ?
D0, hep-ex/0503048
But NP might not be
W

seen in W if q’ is a b,
NP
e.g. FCNC coupling to
the top quark ?
q
q’

u
q
q’
E. Perez

NP
W
t
ET (GeV)
W production at Tevatron
agrees with SM…
19
_
b
tu
W+
SUSY’ 05, 23 / 07 / 05
FCNC couplings to the top quark ?
FCNC couplings tq, tqZ (tqg) where q = u,c can be searched for in single top
prod. at LEP & HERA, in t  qV decays in tt pairs at Tevatron.
 Possible explanation of “the H1 events” ?
H1 @ HERA-I : 5 (3e + 2) of the “isolated
lepton evts” appear top-like ! exp. = 1.31  0.22
H1, EPJ. C33 (2004) 9
ZEUS, PLB 559 (2003) 153.
To explain the “H1 events” as FCNC top production :
need  ~ 0.4 pb (tu ~ 0.2 in the fig.)
Not excluded by CDF & LEP. Not inconsistent with
ZEUS HERA-I modulo little + (-) fluct. in H1 (ZEUS)
tu ~ 0.2 would lead to (single top, FCNC)
of ~ O(1 pb) at Tevatron
NB : getting close
to observe
SM single top at
Tevatron !
Future
HERA &
Tevatron
sensitivities
D0, hep-ex/0505063
E. Perez
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SUSY’ 05, 23 / 07 / 05
Other searches for NP in the top sector
Pair-production of top at Tevatron Run II:  ~ 7 pb
_
• Searches for t t resonances
• Tests of the (V-A) nature of the tbW vertex :
t
l

b
W from t decays are mainly longitudinal (f0 = 70%).
Rest has =-1 (f-1 = 30%). Fit to cos(*) yields :
f+1 < 0.25 @ 95% CL
| R | < 1.05
Yields to (my interpretation) :
if the tbW vertex is :
t  [ (1 + R) – (1 - R) 5 ] b W
(more stringent bounds from b  s but model dependent)
• Constraints on R = (t  b W) / (qW)
• Flavor anomaly in dilepton tt ?
By comparing the number
of tt candidates with
0, 1 or 2 b-tags.
Excess in e, not
stat. significant
(yet…)
E. Perez
21
SUSY’ 05, 23 / 07 / 05
Wbb production at Tevatron
• Enhanced Wbb production ? may occur from
- WH followed by H  bb
- technicolor resonances (T  TW, T  bb)
1 b-tagged jet, sample of ~ 100 events
Search for a mass peak in M(jj) & M(Wjj)
Sensitivity getting close to theo. predictions.
• Run I CDF data : excess of W + 2,3 jets where
both a secondary vertex and a soft lepton are
found in one jet (“superjets”)
Similar analysis carried out on Run II data,
W  e or 
D0, PRL 94 (2005) 152002
Dominant SM contributions from
Wbb ( ~ 3 pb), tt & single top, mistags
No excess observed in the “doubly-tagged”
jet sample in Run II data.
E. Perez
22
SUSY’ 05, 23 / 07 / 05
Very rare processes : B decays
Probe very rare processes : better have a huge lumi… e.g. B-factories.
Tevatron also probes very rare decays, e.g. Bs,d  
Branchings as low as a few 10-8 can be observed.
Known that b  s (~ 3 X 10-4) is a sensitive probe to NP. Eg SUSY, top couplings, …
Recent observation of b  d (5) !
Belle, hep-ex/0506079
Large bckgd (continuum & b  s)
Look in exclusive modes B+  +,
B0  0, B0  . Simultaneous fit assuming isospin relations
BR(B  / + ) =
+ 0.14
1 . 34 +- 0.34
31 - 0 10
0.
X
10-6
.
Consistent
w/ CKM
… Constraints on FCNC top coupling t-u- ?
E. Perez
23
t
Vtb
tu
•
u
*
Vtd
SUSY’ 05, 23 / 07 / 05
Lepton Flavor Violation
• New results (BaBar) on    and   e :
BR(  ) < 6.8 x 10-8
BR(  e ) < 1.1 x 10-7
(hep-ex/0502032)
(prelim.)
BR ~ 10-40 in SM but could be
much enhanced beyond SM
NB : 200 M of ee   evts !
e.g.    constrains a particle coupling both to (l) and to (l), l=e,,
hl hl < 0.18 (MH/1 TeV)2 (my interpretation)
Similar constraints from   e and   e (latter : BR < 1.2 x 10-11, MEGA Coll.)
Example for a doubly-charged Higgs:
• Searches for LFV B-decays : eg Bd  e : BR(Bd  e) < 1.7 10-7 Belle, PRD 68
(2003) 111101
_
23
b

 Bounds on ed b / M2LQ
LQ
e.g. case of Pati-Salam LQs where  = S(MLQ) : M > 46 TeV
d
11
e
Such exchanges are also probed in DIS :
Several examples where DIS constraints
are competitive with those from rare
B decays
ZEUS, hep-ex/0501070
E. Perez
24
ZEUS bounds on eq q / MLQ2
in units of TeV-2, for  LQ types
ed  b
eb  s
SUSY’ 05, 23 / 07 / 05
Exotic experimental signatures
Rich detector capabilities ! search for particles which behave in an exotic way :
 Charged quasi-stable particles : will look like anomalous . Large mass implies :
• a fraction of them will have low =v/c
D0 Run II Preliminary
i.e. reach our muon detector “late”
390 pb-1

Use timing information from  det. to reco 
e.g. allows to set a limit on stable charginos :
M(, “stable”, gaugino-like) > 174 GeV
MC signal
CDF, hep-ex/0503004, 292 pb-1
0
HL
HR
133 GeV
4
10
(1-)/
• Large energy loss by ionisation
 exploit the dEdx measurement
e.g. with cuts for a doubly-charged Higgs,
no candidate while  ~ 40%
m ~ 34 n2 >> e
eg = nhc/4
 Magnetic monopoles M :
- exploit the large energy loss (CDF Prelim.)
H1, DESY 04-240
- Eloss could be so large that M may stop in the beam-pipe ! EPJC xxx (2005)
E. Perez
 Upper bounds on pp & ep (MM)
as a function of M massSUSY’ 05, 23 / 07 / 05
25
Conclusions
The search for new physics is a very active field.
Tevatron & HERA are working very well, the experiments might “see” something
in the near future !
Constraints set on many models, often the most stringent up to date.
e.g.
Z’ and W’ above ~ 750 GeV
Leptoquarks > ~ 250 GeV (Tevatron)
> ~ 290 GeV (HERA, coupling of EM strength)
Randall-Sundrum gravitons > 780 GeV (coupling 0.1)
Complementarity between the experiments.
“Puzzling” events observed at HERA by H1. Clarification (or discovery ?) should
come soon with the increasing HERA-II luminosity.
E. Perez
26
SUSY’ 05, 23 / 07 / 05