# Presentation: 138340

## Emmanuelle PEREZ

- CEA-Saclay,  DSM / DAPNIA / Spp

- Lepton Photon ‘03, Fermilab

- 11 August 2003

-   Not Higgs, not SUSY (cf M. Schmitt’s talk)...
-   Emphasis on recent results
-   Selected topics ...

- XXI International Symposium on Lepton and Photon Interactions at High Energies
- Fermilab, 11-16 August 2003

## “Exotic” Physics : Why ?

-  SM works so far, but raises a crucial question :
-      Where/what is the Higgs boson ?
-      Fundamental scalar field  ??

- Hierarchy pb

- Supersymmetry

- Extra-dimensions

- Dynamical Breaking of EW

- technicolor,  topcolor

-  Questions which the SM (or SM + SUSY) does not answer :
-  Quantization of  EM charge
-  Mass terms for ’s  ?
-  “Replication” of three families ?
-   Additionnal source of CP ?
-   Particle masses & their hierarchy ?
-   Strong CP problem ?
-   Flavor ?     ...............

- Symmetry leptons-quarks ? Magnetic Monopoles ?

- R, Higgs triplets, RpV SUSY  ?

- Compositeness ?  Superstrings ?

- SUSY ( phases ), additionnal quarks ?

- Extra-dimensions ?

- Horizontal Symmetries ?

- “Little” hierarchy

- Axions, mu = 0 ?

## Where to look for ? 

**Where to look for ? **

-  In rare meson decays

-  In Lepton Flavor Violating processes  (  e, e conversion in nuclei ...)

-  In the sky (Cold Dark Matter, SN, red giants...)

-  Various other places, amongst which :  High Energy Colliders

- 99-00 e+ p

- 98-99 e- p

- 94-97 e+ p

- see previous talks

- HERA

- ep, s  = 300 – 320 GeV
- H1 / ZEUS   (colliding experiments)
- until summer 2000 :  120 pb-1 / expt
- Restart (fall 01) more difficult than expected
- Expect high L (high Ie/Ip) back in sep 03

- 1 fb-1
- till
- 2006

- Tevatron

- 2 fb-1
- in
- 06-07

## Any Hints for New Physics ?

- Yes. Neutrinos do oscillate !  But no strong implication in the charged sector...

-  Atomic Parity Violation : weak charge in Cs measured to 0.6 % (1997)
-     > 2 discrepancy with expectation until last spring
-     SM prediction revised – now very good agreement

- Latest : Kuchiev & Flambaum,  hep-ph/0305053

-  sin2W at NuTev ?   Differs by  3  from global SM analysis

-  (g-2) ?

- BNL (ave.)

- ?

- from    had

- from e+e-  had

-  2.5 

- KLOE & BaBar enter the game via
- radiative return data

-  Some interesting events / measurements
-   at colliders ...  Some examples shown in the next slides...

- _

## New Physics in B   Ks ?

- At ICHEP ’02 BaBar & Belle reported a measurement of sin(2) from :

- Hint of new physics in B   K ?  (NP effects might be large in loop induced processes)

- (2002)

- Triggered various speculations...

- SUSY (non-universality), some 2HDM models, extra down quark...

- Looking forward to reducing stat. error in sin(2)K !

- Constrained by
- B mixing and
- b  s ...

## (Run I) CDF events with  + ET,miss + X

**(Run I) CDF events with ******** + E****T,miss ****+ X**

-  Run I ee + ET,miss event : triggered a lot of activity...  ( 10-6 evt expected !)

- Run II data : look for
- events with two
- central ’s

- CDF Run II Prelim, 84 pb-1

- No such spectacular evt
- observed so far ! (CDF & D0)

-  Run I data : slight excess of evts with high ET lepton &  + large ET,miss

- Run I data,
- 86 pb-1

- mainly diboson
- production

- CDF RunII Prelim, 72 pb-1

- Not confirmed
- by RunII data

- (excess mainly
- in  channel)

|  | e+ |
| --- | --- |
| Obs. | 16 |
| Exp. | 7.6
 0.7 |

- CDF, PRD 66, 012004 (02)

- Better hermiticity
- of Run II detector !

- W production at
- Run II : good
- agreement with SM

## CDF “superjets” Events

- 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”)

- 13 evts observed, 4.4  0.6 expected

-  atypical kinematic properties
-  SM reproduces well closely related data
-    samples
-  many, many checks; e.g. that the correlation
-   of SVX and SLT taggers are well described
-   by simulation

- No explanation for this excess.
- Probability (stat. fluctuation)  0.1 %

- Run I “superjets” (CDF)

- CDF Collab, PRD 65 (2002) 052007

- No statement yet from Run II.  Good performance of b-tagging in both
- experiments, but correlations between taggers not yet studied. Work is
- going on in both experiments.

## HERA multilepton events

**H1, hep-ex/0307015, submitted to Eur. Phys. J**

- Search for events with several leptons in final state
- Mainly produced via  collisions

- M12 = mass of
- two highest
- PT e

- (different angular ranges in H1 / ZEUS analyses)

- No excess in ep  X

- 2e

- 3e

**H1**

**H1**

- e

- p

- observed / expected

## HERA events with isolated lepton + PT,miss

**HERA events with isolated lepton + P****T,miss**

| H1 e+ p data | e channel  |  channel  | Combined e &  |
| --- | --- | --- | --- |
| PTX > 25 GeV | 4 / 1.48  0.25 | 6 / 1.44  0.25 | 10 / 2.92  0.49 |
| PTX > 40 GeV | 3 / 0.54  0.11 | 3 / 0.55  0.12 | 6 / 1.08  0.22 |

-  No excess in H1 e- p data
-  No excess in ZEUS data in e &  channels,  candidates
-  Agreement in the had. channel (but large bckgd)
-  W prod : full NLO corrections included
-               (recently available)

- e p   l + jet + PT,miss

-    Main SM contribution :

| ZEUS e p data |  channel |
| --- | --- |
| PTX > 25 GeV |  2 / 0.12  0.02 |
| PTX > 40 GeV | 1 / 0.06  0.01 |

- observed / expected

- PTX

- ZEUS Prelim

-   had

- 130 pb-1

- (W prod)
-   1 pb

- Events

- Events

## HERA events with isolated lepton + PT,miss

****

**jet**

- e

- p

- e p   + jet + X

- e p   + jet + X

## Complementarity of Experiments

- Statistical fluctuation in H1 / ZEUS data ?  The answer should come soon !

- Meanwhile, possible hint for new physics ? i.e. should other expts see something ?

-  e-q resonance ?

- e

- q

- X

- ?

- ?

- ??

- W

-  not a lot of phase space
-  but possibilities exist...
-  if ?? can be pair produced at
-   Tevatron, could look like tt

- 

- q

- W

- had.

- To go further in such comparisons, one needs specific models ...

- Illustrates the complementarity between the 3 colliders

- LEP, e

- HERA, e

- HERA, q

- Tevatron, q

- Adapted from P. Schleper

- “Partonic luminosities”

-  =   PL

- ^

## Models for New Physics

- Try to address one/several  question(s) not solved by the SM...
- Extend the SM by :

-  Enlarged/modified matter field content    - neutrino masses, new fermions
-    to cancel m2h divergences up to ~ 10 TeV ...
-      - may arise in GUTs
-     - possibly together with some new interaction(s)  - dynamical EWSB

-  Enlarged space-time    - hierarchy problem, fermion masses, links with
-      cosmology;  links with string theories

- Build models taking into account precision measurements & bounds from low E

-  Composite fermions
-  Technicolor resonances
-  Leptoquarks
-  Z ’  (W ’)  gauge bosons
-  Models with extra dimensions

- Not covered :
- - Extra generations of leptons
-   or/and quarks
-  Lepton Flavor Violation
-  some models with extra dim.
-  ...

- Covered :

- (a bit...)

## A new scale of matter ?

- Other possible approach IF leptons & quarks have
- common constituents :

- Baur et al,
- PRD 42
- (1990) 815.

- Experimentally  similar, mainly  normalization

-  First approach : assign a finite size to the EW charge
-   distributions. E.g. in DIS at HERA,
-   where Q2max  105 GeV2

-  Interaction between fermion constituents can be
-   parameterized as a Contact Interaction  ( ff  ff )

- Rq < 10-18 m

- Q2 (GeV2)

- d / (d)SM

## Excited Electrons : e + V Resonances

-  Pair production at LEP  masses below  100 GeV ruled out
-  Single production at LEP and HERA

- All e* decay
- modes considered
- at LEP & HERA

- e*  e  at Tevatron

- To fix the ideas :
- M(e*) > 250 GeV

- Take care of
-   conventions !

- Branching ratios of e, eZ, W
- depend on f vs f ’

- contact term

- formalism

- 863 GeV

- M(e*) GeV)

- with  = M

- f = f ’

## Excited quarks & other j-j resonances

**Excited quarks & other j-j resonances**

-  Dijet resonances predicted in various models

-  New fermions, e.g. excited quarks
-      expect signal in q /Z, q W depending on fs vs f & f’
-  new gauge bosons, Z’, W’  (but signal mainly in the dilepton channels)
-  new massive colored bosons, e.g. SU(3)1 x SU(3)2  SU(3)QCD
-   ( chiral color, colorons, topgluons...)

-  Look for a narrow resonance in the di-jet spectrum : use a simple background
-   parametrization for d/dM and search for bumps  resolution

- Narrow
- resonances
- compared to
- (Mjj)  10% Mjj

- 200

- 1100

- 1

- 10

-  Axigluon & (flavor univ.) colorons :

- assuming
- (qqg) = (qqG)

- M > 1130 GeV

- First direct bound > 1 TeV !!

-  Excited quarks :

- M > 760 GeV

- (f=f’=fs=1,  = M)

## New Physics in the Top Quark Sector ?

-  Topcolor : introduced in DEWSB models to account for large Mtop

- SU(3)1 x SU(3)2  SU(3)QCD  with e.g. SU(3)2 coupling strongly to 3rd gene only

-  Topgluons coupling mainly to bb, tt

- Avoid a large mass for b ?
-       e.g. a new Z boson, attractive to tt
-          & repulsive to bb

- i.e. no bb condensate

-  “ Little Higgs” models

-    New heavy T , could be observed in

- ATLAS

- L = 300 fb-1

- Bckgd =
- tZ, WZ

- Look for a tZ resonance

- NB : “recent” model... experimental studies have
-          already started !

- q b  q’ T

- Might expect
- some
- tt resonances

- Large top mass... Might expect first hints of new physics in the top sector

- +  T  tZ  3 leptons

-  Single Top production @ Tevatron

- Should be observed with  2 fb-1

- Might bring surprises, eg Vtb, anomalous couplings

- _

## FCNC couplings involving the top quark ?

**FCNC couplings involving the top quark ?**

- Anomalous couplings between top, /Z and u/c may arise in SM extensions.
- Would lead to:

-  enhanced single top production @ Tevatron
-  single top production at LEP & HERA (tiny rate within the SM)
-   ( HERA has  no sensitivity on couplings top-c)
-  t  u/c + /Z   @ Tevatron

-  not excluded by LEP & Run I data
-  ZEUS vs H1 : too few events so far...
-    looking forward to doubling L !

- H1 Prelim., Contrib. Paper #181
- ZEUS Collab., PLB 559, 153 (2003)
- Final DELPHI results, Contrib. Paper #53
- L3, PLB 549 (2002) 290

- Possible explanation of HERA’s events ?
-  e q  (e) t  (e) + b + lepton + ET,miss

- H1 : 5 candidates, 1.70.4 expected (Prelim.)

- (CDF Run I)

- Coupling top, q, Z

- Coupling top, q, 

- 0.2

- 0.2

- 0.4

- 0.6

- Sensitivity @Tevatron :
-  mainly via radiative top decays
-  u/c   t :  quite large but huge bckgd !
-   for   0.2,    (SM single t)  2 pb...

## Lepton + Quark Resonances : Leptoquarks

- Exact cancellation of QED triangular anomaly ?

**Lepton + Quark Resonances : Leptoquarks**

-  (unknown) Yukawa coupling lepton-quark-LQ

- ZEUS, DESY-03-041

| Topologies | SM Background |
| --- | --- |
| e + jet | Neutral Current DIS
Exploit specific angular distribution of LQ decay products |
|  + jet | Charged Current DIS |

-  Single LQ prod at HERA

- Look for a resonant peak in M spectra
-                    reduced background

- No excess observed in both channels

-  LQs appear in many extensions of SM
-   (enlarged gauge structure, compositeness, technicolor...)
-  Connect  lepton & quark sectors
-  Scalar or Vector color triplet bosons
-  Carry both L and B,  frac. em. charge

## First Generation Leptoquarks at Tevatron

**First Generation Leptoquarks at Tevatron**

-  Pair production at Tevatron

| Topol. | SM Background |
| --- | --- |
| eejj | DY + jets,
QCD “fake”, top |
| ejj  | QCD, W + jets,  top |
| jj  | W ( / ) + jets
Z () + jets
QCD |

- Require a good
- understanding of
- missing ET !

- Make use of ST =  ET

|  | D0 | CDF |
| --- | --- | --- |
| eejj | 0 / 0.45  0.12
(135 pb-1) | 0 / 3.4  3.2
(72 pb-1) |
| ejj | 3 / 4.19  1.00
(121 pb-1) | 2 / 1.73  1.40
(72 pb-1) |
| jj | __ | 42 / 42.5  10.7
( 76 pb-1) |

- No attempt to reconstruct the LQ mass

- jj channel

- Mainly from
- the data

-  rate for a jet to “fake” an e
-  use of control / bckgd
-   enriched samples
-  correct the O(s0) MC to
-   reproduce the observed jet mult.

- Mainly W+jets
- QCD dominates
- at large MT
- & ST

- Bckgd
- well
- controlled

- Missing ET (GeV)

- QCD

- Transverse mass (e, ) (GeV)

- ejj channel

- D0, 121 pb-1

## Existing Bounds on 1st Generation LQs

| e | Run II bounds |  |
| --- | --- | --- |
| 1 | 231 | D0 |
| 1 | 230 | CDF |
| 0.5 | 166 | CDF (ejj) |
| 0.5 | 169 | D0 (eejj) |
| 0.5 | 156 | D0 (ejj) |
| 0 | 107 | CDF |

- D0 Run II + D0 Run I : M > 253 GeV for =1

-  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

-  = BR( LQ  eq )

-  = 1

-  = BR (LQ  eq)

- MLQ (GeV)

## Second and Third Generation Leptoquarks

- Already competitive
- with Run I
- result (200 GeV)
- obtained from a
- NN analysis

-  Search for LQ2 & LQ3 using heavy
-   flavor tagging  ( Run I results ) :

- LQ2  c
- LQ3  b, LQ3  b

- CDF, PRL 85  (2000) 2056

|  | Scalar |
| --- | --- |
| 1 | 99 |
| 0 | 149 |

- ... New physics might couple
- mainly to 3rd gene fermions

- Run II will bring much more
- sensitivity (improved SVX)

- So far, LQ2,3 with M > 100 GeV can be probed  exclusively at the Tevatron !

- (b)

- (b)

## Dilepton resonances

**Dilepton resonances**

-  New heavy gauge boson Z ’, e.g. models with L-R symmetry or E6 GUT inspired
-  Kaluza-Klein gravitons in some extra-dim. models
-  (Color-singlet) technirho in Technicolor models ...

| ee | DY,
QCD “fake”  |
| --- | --- |
|  | DY |

- Model  couplings of Z ’ to fermions;
-              mixing with the Z  0 (mainly Z peak data)

- D0 & CDF searched for ee &  resonances :

- direct

- Run II direct
- bounds between
-  545 and
- 730 GeV

- D0 Run II Prelim, 122pb-1

- Expected signal
- MZ ’ = 750 GeV

- QCD “fake”

- Main bckgds @ high M :

- Already competitive with indirect LEP bounds

- CDF Run II Prelim

- 126 pb-1

- 

- ee

## Status & Prospects on New Z’ Bosons

|  | LEP
Combined | APV
(*) | CDF ee+
(126 pb-1) | D0 
(100 pb-1) | D0 ee 
(122 pb-1) |
| --- | --- | --- | --- | --- | --- |
| SSM | 1787 | 835 | 730 | 610 | 719 |
|  | 673 | 740 | 590 |  |  |
|  | 481 | - | 605 |  |  |
|  | 434 | 540 | 630 |  530 |  605 |

- Indirect bounds from LEP
- much more model dependent

- APV ? QW would need
- to be measured within 
- 0.1% to compete with LHC

- (*) my estimations using Casalbuoni et al, PLB 460, 135
-                                     & Kuchiev & Flambaum,  hep-ph/0305053

- my estimations from
- D0 bounds on  x BR :

##  l+l+ Resonances ? E.g. Doubly Charged Higgs 

- Appear in L- R symmetric models :   SU(2)L x SU(2)R broken by Higgs triplet
- (or extended Higgs sector by a triplet with Y=2).  Might explain small (Majorana)  masses.

-  LEP & Hera : single production via e+   e- H++

-  Tevatron : pair
-   production dominates

- H1 2e & 3e events at high M :
- only one 2e evt fulfils charge
- requirement

- H++ couples to fermions via unknown Yukawa couplings hij, not related to masses
- SUSY L – R models predict low H++ masses, below  1 TeV

-  Pair production at LEP : H  ee, , , e, e,  considered

- MH > 98.5 GeV

- No sensitivity yet !

- Run II should probe
- masses up to 180 GeV

## Search for H   at Tevatron

- Look for events with at least 2  and one pair of  with like-sign charges

-  Basic  like-sign selection :

- _

- Mainly  bb events

- Rate well described by SM prediction
- when bb expectation is rescaled following
- Run I ( bb, inclusive) measurement

- _

- _

-  Signal selection   2 candidates (exp. 0.34  0.1)

- MH > 116 (95) GeV
- for L (R) H  

- D0 Run II, 107 pb-1

- Could this be the
-  1st ZZ candidate
- in Run II ?

- 1-

- 2+

- 3-

- 4+

- M(12) = 91 GeV

- D0, Preliminary

- (similar result from CDF)

-  CDF also looked at
-   non-diagonal coupling
-   H  e 

-  MH > 110 GeV

## Kaluza-Klein Gravitons

- Why is the gravity so weak, i.e. MPl >>> MEW ?
-          All attempts  higher dim. space, with n compactified extra dimensions

-  “Strong gravity” ; fundamental scale ~ TeV;  gravity appears weaker in
-   4d because flux lines are “diluted” in large extra dimensions
-   Large Rc  0.1 mm. Not excluded by  gravity measurements
-       Arkani-Hamed, Dimopoulos, Dvali,  PLB 429 (1998) 263
-        revived ideas in Antoniadis, PLB 246 (1990) 377.

- Randall & Sundrum models; “usual” version : n=1, Rc  Planck length

-  “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

- In localized gravity :

- PRL 83 (1999) 3370;
- PRL 83 (1999) 4690

- CDF : qq, gg  ee, ,  jj

- Spin 2
- resonance

- Coupling k/MPl

- G(1) mass (GeV)

- First direct constraints on Randall-Sundrum models !

- CDF Run II, Prelim, 126 pb-1

- ee &  combined

- Graviton propagate in extra dim  Kaluza-Klein modes

## Kaluza-Klein Gravitons in Large Extra Dim

- Very different phenomenology if “large” extra dimensions.

- G(k) with quantized momentum qT = k/R in extra dim :

| 4+n dim | 4 dim |
| --- | --- |
| Massless graviton G(k) | Massive graviton G(k) |
| with momentum qT = k/R | with m2 = k2/R2 |

- R  0.1 mm  i.e. 1/R  1 meV  Mass “continuum”,
- “first” states very light !!

-  Hadronic colliders : mainly jet + Missing Et

-  D0 & CDF (Run I) : bounds  1 TeV
-  LHC (100 fb-1) : reach  7 – 8 TeV

- (n=2)

- Direct probe of MD

## Kaluza-Klein Gravitons in Large Extra Dim

- Interference of G(k) exchange with
- SM processes affects observables

- divergent for n > 1...

- (  1 / (i2+j2+...) DV )

- Effective coupling with
-  = O(1), MS = O(MD)

- (various formalisms...)

-             i.e. not a direct probe of MD

-  Bhabha &  at LEP
-  NC DIS at HERA
-  ee & ,  at Tevatron

- MS > 1.35 TeV
- MS > 0.82 TeV
- MS > 1.28 TeV

- “GRW” formalism :

- D0 Run II
- 100 pb-1

- (also CDF, ee & , Run I)

- With 2 fb-1, MS up to  2 TeV can be probed
- at the Tevatron

- for the
- 1st time
- in pp

- (LEP combined, Bhabha)

- ee & , 128 pb-1

- instr.
- bckgd

- (D0 Run II, Prelim., ee & )

- 1.38 TeV
- combined
- with Run I

## New ED Searches from LEP: Branons & Radions

-  LED : Remind the DV problem in (tree-level) amplitudes involving G(k) exchange...

- Allow the SM brane to “vibrate” in the extra dim, on a length 1/f
- Emission/absorption of KK modes  brane deformation; larger deformations  higher modes
- Large 1/f (small tension)  Strong suppression of G(k) emission for large |k| !
-                                             might regularize the DVs, but suppress the standard signal !!

- Scalar field associated to the brane vibrations : “branon” 
- May be pair produced, e.g. e+e-   , coupling  1/f4

- f << MD : branon sig.
- f >> MD : graviton sig.

- gravity
- expts

- SN
- 1987A

-  Extra dim models : also new scalars
- In RS model : only one, the radion R
- Mixes with the Higgs, large coupling to gg

- Re-interpretation
- of the flavor ind.
- Higgs searches

- <R> = W

- M(h-like) > 58 GeV

- First collider bound
- on Higgs-radion

- OPAL, contrib
- paper #238

## “Signature Based” Searches for NP

- (Quasi) “model-independent” search for new physics :
-  definition of objects (e, , , , jet, W, Z, ...)
-  look at data vs SM in all “channels” with > 1 object
-  in each channel, find the part of  space with largest deviation (e.g. in M,  pT )
-  quantify the agreement using “Gedanken” (Mock, MC) expts

- Pionnered by DZero with
- the full Run I sample

- D0, PRD64, 012004 (2001)

- Applied recently to the full sample of H1 data

- # Events

- 2B

- 3B

- 4B

- Requires a very good understanding of
- detector & backgrounds !

-  overall very good agreement H1 data / SM
-  retrieves the “lepton-jet-ET,miss” and
-   “multi-electron” anomalies
-    (dedicated analyses might be more sensitive)

- H1, contrib paper #195

## Searches for Magnetic Monopoles

- (Dirac) Magnetic Monopoles may explain the quantization of Qem

- -i = /L

- + 0 g / L

- eg = nhc/4

- If light enough, could be produced at colliders: pp, ee, ep  MM  (via )

- Might affect     via a Monopole (M) loop. Prediction ??  (non-perturbative...)

- High energy loss  might be stopped + trapped in material (e.g. beam pipe)

- H1 used its (old !) beam pipe, cut it in strips & analyze with a SQUID

- distance

- SC coil

- Cabrera, PRL 48

- Candidate !

- search in
- cosmic rays,
- SLAC (81-82)

- Calibration using “pseudo-poles”;
- sensitivity of  0.2 gD

- No such
- signal in
- H1 BP !

- Similar studies using pieces of D0 & CDF detectors & BP

- H1 Collab
- contributed
- paper #186

- Kalbfleisch et al,  PRL 85 (2000) & hep-ex/0306045

## Conclusions

-  Many new results from Tevatron experiments using Run II data.
-   No signal for new physics observed so far.
-   Constraints set on many models, often the most stringent up to date.
-   Established the good performances of key components of the detector.
-   Good understanding of SM physics as seen in the detectors.

-  “Puzzling” events observed at HERA. Clarification (or discovery ?) should
-    come soon with HERA-II luminosity.

-  We do not know what form “new physics” will take, but expect to see
-    something at the TeV scale. Could happen soon :

- Apologies for results I did not present, for mistakes, for missing references.

-  at Tevatron & HERA, within models & beyond models
-  in precision measurements, rare decays and LFV processes
-  or a bit later with the Large Hadron Collider...

- Within the next 10 years we should have a much deeper understanding
- of fundamental physics at the highest energy scales !