Transcript Document 7260516

INFN Roadmap
WG
“Upgrade di luminosità di LHC”
(SLHC)
Convener: M. de Palma
Out line




Participants
Physics issues
Detectors point of view (limited to those in which INFN
Conclusion and question to WG
is involved)
NB: WG have still not looked at trigger, DAQ and costs.
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Participants

Theorist: Frixione,Colangelo

Atlas: Laurelli, Dardo, Meroni, (ID), Citterio, Costa (ECAL), Del Prete
(Hcal), Bagnaia, Nisati, Primavera (MU), DiCiaccio, Veneziano (Trigger)

CMS: Messineo, Palla, Bisello (Tracker), Pastrone, Ragazzi (ECAL),
Dalla Valle, Paoloucci, Zotto (MU)

LHCb: Bencivenni(Tracker), Lai(Elet.), Marconi(Trigger)
+ all expert and volounteers……….
First meetings held the 17 Oct. and 14 Nov.
Next meeting 24 Nov.
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Physics issues
Two (obvious) caveats:
 The physics program
of a luminosity upgraded SLHC will be mainly
determined by the discoveries and the experience collected at LHC in a
few years of running
 Discussion is based on existing studies (starting point for subsequent
work)
There hasn't been much of theoretical activity recently specially devoted to
SLHC. There is of course a lot of work done for LHC, which will be fine for
SLHC as well.
Main reference:
SLHC physics and detectors: F. Gianotti et al., Eur. J. Phys. C 39 (2005) 293
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Scenario
LHC
SLHC
s
L
Bunch spacing t
14 TeV
1034
25 ns
14 TeV
1035
12.5 ns *
pp (inelastic)
N. interactions/x-ing
(N=L pp t)
dNch/d per x-ing
<ET> charg. particles
~ 80 mb
~ 20
~ 80 mb
~ 100
~ 150
~ 450 MeV
~ 750
~ 450 MeV
Tracker occupancy
Pile-up noise in calo
Dose central region
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~3
10
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Physics motivation
Tanks to S. Frixione
and P. Colangelo
Tests of the SM:
Multiple gauge boson production
Triple gauge couplings 
Higgs physics:
Higgs pair production and trilinear coupling 
Couplings to bosons and fermions
Rare Higgs decays
Scattering of VB:
( i.e. new strong interaction regime) 
Susy:
Heavy Higgs bosons of MSSM 
SUSY particle reach 
Exotica:
Heavy gauge bosons 
Quark compositeness
Extra-dimensions
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Triple gauge boson couplings (I)
Three- and (four) -vector-boson couplings are a direct
consequence of the non-abelian gauge structure of the SM. In the
SM they are uniquely fixed, extensions to SM induce deviations
(form factors are introduced ->  scale of new physics)
LHC favourable channels :
W  ℓ 
WZ  ℓ  ℓ ℓ
Expected sensitivity to TGC,
95% CL constraints, ATLAS
5 parameters introduced to describe TGCs:
g1Z (1 in SM), kz, k, , z (0 in SM)
W  probes k ,   and WZ probes g1z, kz, z
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Triple gauge boson couplings (II)
Correlations among parameters
14 TeV 100 fb-1  LHC

kZ
28 TeV 100 fb-1
14 TeV 1000 fb-1  SLHC
28 TeV 1000 fb-1
Z
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Z
SLHC improves LHC
results by at least 50%
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Higgs pair production and self coupling (I)
Two Higgs radiated independently (from VB, top) and trilinear self-coupling terms
proportional to HHHSM. Higgs self-interactions fully determined in the SM after
fixing mH Tests of SM EWSB sector
qq ->VHH
qq -> qqVV -> qqHH
very small cross sections, hopeless
at LHC (1034), hope at SLHC
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Higgs pair production and self coupling (II)
ATLAS: preliminary study for
SLHC (1035 cm-2 s-1)

a first measurement of HHH is
possible (170 < mH < 200 GeV)
better than 25%.
Cross sections for Higgs boson pair production in
various production mechanisms and sensitivity to
HHH. Arrows correspond to variations of λHHH
from 1/2 to 3/2 of its SM value
gg  HH 
W+ W– W+ W–  ℓ±jj ℓ±jj
with same-sign dileptons
Probably a strongest physics case for SLHC
A delicate counting experiment: background control essential
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Scattering of vector bosons
If no (light) Higgs, anomalies should appear in VB scattering:
 deviations in WW scattering
 resonance production
This should be a possible onset of a new strong interaction regime
Vector resonance (r-like) in WLZL
scattering from Chiral Lagrangian
(BESS) model
Scalar resonance in WL WL, ZL ZL
-> ZL ZL scattering (BESS model)
S
V
Preliminary results indicate that these should be observable at SLHC, but
not at LHC  A “discovery" at SLHC
A counting experiment; good background knowledge mandatory
Detectors must have good jet-tagging and jet-veto capabilities
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Heavy Higgs bosons of MSSM
The MSSM features a rich Higgs sector (h;H; A;H). The discovery of its heavy
part could be beyond reach at LHC for large mA
LHC 300 fb-1
green: region where only
one (the h, SM-like)
among the 5 MSSM
Higgs bosons can be
found (assuming SM
decay modes)
SLHC 3000 fb-1
MSSM parameter space regions for > 5  discovery for the
various Higgs bosons (both experiments combined)
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A 95% C.L.exclusion
boundary is a further
~ 50 - 100 GeV to the
right of the discovery
boundary
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SUSY particle reach
Higher integrated luminosity  obvious increase in mass reach in g~ , q~ searches
5-discovery countours
SLHC improves LHC reach for g~ , q~ up to 0.5 TeV
(to ~ 3 TeV in mass) with inclusive searches.
But this is just “ the reach”: the main advantage
of increased statistics should be in the sparticle
spectrum reconstruction possibilities. Some
exclusive searches be come possible at SLHC
g~ , q~
SLHC
LHC
g~ , q~
But for decay studies good detector performances
are needed: lepton, jets, Emiss, b-tagging……
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Heavy gauge bosons
Additional heavy gauge bosons (W,Z-like) are expected in various
extensions of the SM symmetry group (LR,E6,SO10…..), with couplings to
leptons ~ similar to SM W,Z
Ex. sequential Z’ model
Z’ production and Z’ width
(assuming same BR as for ZSM)
For high mass objects electrons more usefull
than muons - thanks to better resolution
Expected backgrounds from Drell-Yan and
tt production at the few % level
With 10 events to claim discovery, reach improves from 5.3 TeV
at LHC to 6.5 TeV at SLHC
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LHC luminosity profile vs physic cases
cm-2s-1

De Negri
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Physics summary
 Significantly increased physics reach in all typical LHC physics
channels.
 These improvements are, at least, better measurements and better
exploitation of the LHC energy domain and make the LHC
upgrade very attractive and an obvious next
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SLHC Scenario
The most relevant SLHC parameter for experimental apparatus are:
(from W. Scandale talk)
 BCO interval:
 Forward area:
 Timescales:
 Environment :
(?)25ns, 15ns, 12.5ns, 10ns
The closest machine element will be move towards the IP
Assume 2014±2 years
Increased radiation levels (and resulting activation)
The luminosity will increase as function of time at LHC, we will need to upgrade the
detectors in time to take the maximum advantage of this.
We know that some parts of the detector systems might have performance problems
or operational problems, and therefore interventions and improvements are require.
Issues:
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Radiation damage
Pileups of MB events
Bunch spacing and trigger Timing
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Basic assumption for detector up-grade
 To take advantage of a luminosity increase the detector performance
of ATLAS and CMS have to be kept at foreseen actual level ( i.e
tracking, b-tagging, vertexing, energy resolution and momentum
measurements)
 The detector changes have to be “reasonable”. We cannot replace the
entire detectors for obvious reasons of cost and time.
 One would like to keep as much as possible of the existing large
items (calorimeters, muon systems, magnets, cooling, gas, cables,
pipes, support structures, movement systems, cryogenic systems,
etc).
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…… work are already started ……
In the experiment;
ATLAS: Steering Group established, two workshops in Feb and July 2005.
– Plan to organise R&D with Steering Group and Project Office as part of
technical coordination to ensure coherence.
CMS: Three workshops on SLHC; Feb 2004, July 2004, July 2005. (next Apr 06)
– To assist in the R&D project definition, already agreed CMS peer-review
scheme. Main lines identified:
• Tracker & Trigger
• Microelectronics and Power
• Optoelectronics & data architectures
and ouside experiment ( also inside INFN-G5 programs)
• RD50 in the area of radiation hard sensor R&D
• Activity on rad-hard electronics
• Simulation study
– ....and could be that those attivities faster increase with the end of
construction tasks of the LCH experiment
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ATLAS - Muon system from P.Bagnaia, L. Nisati
MDT
Muon system designed with a 5 safety
margin on bck rate
The detector performance should be Ok
with a acceptable degradation of the
spatial resolution.
The Front-end electronic should be Ok
with some problems with high rate but on
DAQ side.
Single tube resolution
(bck x 5, x 2 worsening
for charge fluctuation)
SLHC
Also the LV1 electronic should be Ok
•If BC < 25 ns
•If the trigger decision can be taken on 2
and BCID done al LVL2
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ATLAS - Muon system from A. Di Ciaccio
At SLHC additional shielding and
beryllium beam pipe should be inserted
RPC
to further decrease (x 2 reduction) the
background rate The expected rate in
All along the test (8 ATLAS year, safety
the Barrel muon system could be
factor 5 = 100 Hz/cm2), chamber performance estimated ~50-100 Hz/cm2
(efficiency, cluster size, rate capability) have
remained largely above the actual ATLAS
requirements and cover the SLHC request.
SLHC
(provided that Temperature, RH of the
environment and gas mixture are kept at a
Few Hz/cm2
proper value)
500
Hz/cm2
The detector performance should be OK
Since all tests have been done with final
Front-end electronic that should be also OK
(without safety factor on bkg level)
RPC efficiency after 7 ATLAS year
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CMS - Muon system from M. Dallavalle
MDT
The detector performance should be Ok
but study on general ageing are still needed.
Since chamber will demand higher currents than now available,
HV PS system would require some upgrading
SLHC would require a full redesign of the trigger and readout
electronics, in new technologies to cope with radiation environment,
(and to be able to operate at 80 MHz)
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CMS - Muon system from P. Paolucci
RPC
•BARREL: muon rate ~10 Hz/cm2, n and  < 40-50 Hz/cm2
•ENDCAP: muon rate ~10 KHz/cm2, n and  < 10 KHz/cm2
GIF Test on production chamber (equivalent to ~ 15 CMS years)
have shown good efficiency and stable current
The detector performance should be Ok
but without safety margin, more studies needed
Front-end work up to 5 MHz  Ok
Trigger electronic should be Ok but it is at limit.
Situation is very different for End-Cap where even the detector technology
is no more adequate
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Atlas – LAr Calorimeter from M. Citterio
The liquid argon calorimeter was optimized for the nominal LHC
luminosity, a x 10 increase of this luminosity would rise concerns on:
Space charge effects → signal reduction
Argon contamination → signal reduction
Charge density increase → pile-up
Activation → noise increase
phase instability → operation problems
Voltage drop in the HT distribution → rate dependent response
General radiation damage of electronics → single element (now built
in 13 different ICs) could not be changed (next slide)
8) The high occupancy of SLHC require a new read-out chain design
9) A BC rate > 40 MHz require new pipeline
1)
2)
3)
4)
5)
6)
7)
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Overview of main components on a FEB
128
input
signals
Analog
sums
to TBB
32 0T
32 Shaper
2 LSB
14 pos. Vregs
+6 neg. Vregs
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2 SCAC
2 DCU
16 ADC
8 GainSel
1 Config.
1 SPAC
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DMILL
AMS
DSM
COTS
1 MUX
1 GLink
7 CLKFO
1 TTCRx
1 fiber
to
ROD
TTC,
SPAC
signals
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Atlas – LAr Calorimeter(II)
15 Those affects as expected to be non critical and, since it is
impossible to change the detector, we have to survive. More
study to drive an optimization strategy are needed.
Detector is assumed to be Ok
6
The HV system will be revisited and HV filter must be
redesigned to reduce the rate fluctuation response and noise.
79 A complete new architecture of the read-out system is
needed.
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Atlas -Tile hadron calorimeter from T. Del Prete
Detector should be OK
A decrease of the light budget produces a degradation of the energy
measurement (3-5%) which effects Jet Energy Reconstruction.
/E ≈ 10% @1034  ≈ 30% @ 1035 for Ejet = 100 GeV
All Electronic components have been tested above the rad doses for 10Y
@ 1034 . They should survive 5Y @ L = 1035 but no NO safety margin.
Some part: (Mother Boards, Digitisers, Interface…..) are more rad-fragile
If SLHC needs to increase BC rate, all the F/E logic has probably to be
redesigned.
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CMS – EM Calorimeter from N. Pastrone
Crystal
The dose in the Barrel ( = 2.4) goes from 0.15 Gy/h @ 1034 to 1.5 Gy/h, in the
EndCap it reaches 30 Gy/h at  = 2,6 and 75 Gy/h at  = 3.
Those produce at SLHC a
significant change in LY:
<LY> drops by ~25% in
barrel, 30% Endcap.
In EndCap we are close to
the “saturation” condition.
Still more study are
needed ( irradiation test,
calibration study…)
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LY for different densities of colour centres
( Radiation damage increase colour centres)
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CMS – EM Calorimeter (II)
Photosensors
In Barrel, sensible increase of leakage current (130 A at SLHC) of APD is
expected. It translates in large increase in electronic noise ( ~190 MeV per
channel with respect to ~ 40 MeV al LHC) (study performance with higher
n fluxes)
In Endcap, VTP glass window has to be tested at the expected dose.
In conclusion:
Considering work for disassembly and refurbishing (at least 2 years) and
the costs involved, ECAL barrel could be used even with a degradeted
performances (to be studied !) due to decrease of LY, increase of noise and
pileup.
For the Endcap, the situation is more difficult.
Read out chain should be OK for BC 2 X 40 MHz
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Inner tracking detector
General consideration:
The limiting factor for the detector lifetime
will be radiation damage, which is mainly a
function of the integrated luminosity.
Assuming 3000 fb-1 at SLHC ( x 6 the
integrated luminosity for which currently
planned silicon system has been designed)
the hadrons fluence and radiation dose at
different radius are:
LHC
SLHC
Cumulative effects (NIEL, TID) increase by a factor 5
Instantaneous effects (occupancy, SEU) increase by a
factor 10
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Inner tracking detector
General considerations:

The silicon sensor, both strip and pixel, would suffer substantial
radiation damage strongly degrading the performance.
 For the electronic, the situation is somewhat more favourable but similar.
 Most of material (frames, glues, insulators… etc.. are not tested to the
dose above.
 The inner detector system must be completely
rebuilt, both for ATLAS and CMS
The bunch timing should have a strong impact on tracker project, both on
sensor and electronic. Shorter Bunch give less occupancy but requires
better time resolution……
Information for Atlas came from a 3 days dedicated Workshop (1820/07/2005) in Genova: http://atu-2005.ge.infn.it/ while the CMS
comments presented here are only representative of our present
thinking.
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Trackers Sensor Material issues
• Substrate
– Outer layers, silicon looks promising
• n+-in-n (as for today pixel), p-type floating zone FZ (50% cheaper,
need single side processing) for μstrips Oxygen doped, Magnetic,
High resistivity
– Inner region - no proven alternative to silicon yet - but are other
materials possible?
• Performance
– Series noise (Cdet) can decrease but parallel (Ileak) may not (Ileak ~ strip
length, thickness, particle fluence)
– Charge collection, high bias voltage (>1000 V), S/N
• Structure
– Pixel and pixel 3D, short strips, 2D detectors (stripxel), SS, DS
• Power dissipation
• Manufacturability
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Trackers Electronic issues
• Very rad-hard electronics
Single Event Upset (SEU) will be a serious problems.
• Technology and design
0.13 µm or smaller CMOS for Pixel, BiCMOS e CMOS per strips:
• Data rate / opto-links:
• Power scheme
• Trigger
(with muon system, very appealing but difficult, some ideas from CMS)
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Trackers design issues
• Dimensions
sensor size, finer pitch, number of different nodule type,….
• Ease of handling and assembly
We must minimize handling - could this be done by industry?
Should be base units still the Module or Stave or Sector (could high
integration give yield problems)?
• Module construction
• Integration (still to proof al LHC!)
• Cost
– Present design originates in bottom-up approach, underestimates many
costs and difficulties
– Need we approach !
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ATLAS Tracker, from G. Darbo
Number of layers 8÷11 (most probably 10):
Inner layer:
Pixel, 3÷4 layers, 300÷400 µm x 50 µm, 2.9÷3.7 m2.
Middle layer:
short strips or stripxel, 3÷4 layers, 3.5 cm x 80 µm, 21÷27 m2.
Outer layer:
µstrips, 2÷4 layers, 9 cm x 80 µm, 116 ÷ 327 m2.
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CMS Tracker
from F. Palla
Inner part (R< 60cm)  Pixel layers
•Pixel system 1 - 1 layer at radius about 7 cm
– Change detector more often (annually)
– Improve fluence limit of sensor. Need to study sensors more RD50 activity
fundamental research rather than development)
•Pixel System 2 - 2 layers at 18 and 22 cm ( need cheaper pixel technology)
– Single sided pixel detectors, n+ on p – Silicon (Czochralski)
– Large Module size, e.g. 32 x 80 mm sensitive area
– Pixel area ~ 160 mm x 650 mm
•Pixel System 3 - 3 Layers 30, 40 and 50 cm
– Macro pixel detectors of 1 mm x 1 mm/ Micro strips of 200 mm x 5 mm
– Simple DC coupled p+ on n – Silicon detector
External part ( R> 60cm)  strip layer
•Strip System 3-4 Layers fro 60 to 110 cm
– About similar to present one
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Schedule
The WG idea about time:
 2006-2008 General R&D program ( maybe shared with other programs
(ILC, -factory, etc…)
 2009-2010 Definition of detector upgrading design within clear SLHC
machine project.
 2010-2012 (?) Prototypes, modules “0”, start of construction
 2012- 2015 (?) Construction
 2015(?)- 2017(?) Assembling, integration, commissioning….

Running
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Conclusion
• The Inner Detectors will need to be replaced (the actual have been
designed for a lifetime of 10 years at 1034).
• Ageing and space-charge effects of calorimeters and muon chambers,
due to the radiation and activation levels increase, need to be studied in
more detail to point out the optimization and/or modifications needed
with the goal to change as little as possible. The read-out electronic
chain in some case, need to be replaced
• Depending on the chosen BCO frequency - the impact on the existing
electronics can change significantly.
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Questions to WG (I)
1) Physics case
There is!
2) Competition and competitivity
No competitors are
foreseen in the SLHC time
scale
3) Interest of INFN teams involved in
LCH exp. to participate ad SLHC:
a) On same item
b) On new item
At moment, all team show
interest toward SLHC on
the same LHC item
4) Needed upgrade to the different
detectors in both exp. considering
the different LHC upgrade
scenarios
Subject of firsts WG
meetings, we have
reported here ………
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Questions to WG (II)
5) Within the different LHC upgrade scenarios
and after the first LHC results when (and
how) decide to start:
a) the dedicate R&D
b) the experiment upgrade
(a later start of dedicate R&D could
compromise the detector upgrade)
More detail should be point
out in next meetings……..
6) Within the different LHC upgrade scenarios
versus SLC:
a) The detector up-grade cost
b) Their share(?)
c) The dedicated R&D cost
next meetings …..
7) Two experiment remain general purpose
experiments.
8) Still two experiment are needed.
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at moment, seem yes
seem yes
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Other physics case
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Higgs couplings to fermions and bosons
Combining different production mechanisms and decay modes get ratios of
Higgs couplings to bosons and fermions. Ratios of rates are theoryindependent measurements; i.e. are independent form σtot Higgs, ΓH, and Lint.
full symbols: LHC (300 fb-1 per exp)
open symbols: SLHC (3000 fb-1 per exp)
qqHWWqqH
ttHttHbb
HHZZ
HWWHZZ
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HWWHtt WHWWWHWW
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It is mostly statistics
limited at LHC therefore
should benefit from
SLHC luminosity
increase  provided
detector performances are
not significantly reduced.
At the SLHC the
ratios of Higgs
couplings should be
measurable with a ~
10% precision
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Multiple gauge boson production
Test of high energy behaviour of weak interactions
W and Z -> leptons cleanest channel, but the rates are limited at LHC -> SLHC
expected numbers of events in purely leptonic final states, 3 and 4 Vector Boson production,
SLHC 6000 fb-1
(lepton cuts: pt > 20 GeV, || < 2.5, assumed reconstruction efficiency 90%)
WZZ -> 5 leptons, ZZZ -> 6 leptons accessible at SLHC
WWWW -> 4 leptons could allow to put limits on 5-ple coupling (zero in SM)
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Higgs rare decays
Increased statistics would allow to look for rare decay modes (difficult to
observe at LHC). A couple of cases with BR=O(10-4) have been considered.
HSM  Z 
ℓ+ ℓ- 
•At the LHC (300 fb-1/experiment) signicance is about 3.5 
•At the SLHC (3000 fb-1/experiment) signicance is about 11 
 HSM  + Impossible to discover at the LHC
(significance <3.5) while at
LHC expected significance
 5s
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Compositeness
Quarks (and leptons) may be composite structures, bound states of
“preons", whose interactions are characterized by a mass scale 
Symmetry considerations imply that  > O(1 TeV)
A counting experiment:
a) deviation in high-pT SM jet production
b) angular distribution of the jet pairs
from QCD
Effect of compositeness
May not be observed at LHC, but evidence at SLHC
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Extra-dimensions
Theories with extra dimensions lead to expect characteristic new signatures
/signals at LHC/SLH. Various models exist and their scales are completely
unknown.
As a result, an immense spectrum of possibilities opens up in a high-energy
regime.
Strategies are typically based on (direct or indirect) graviton and/or on
Kaluza-Klein excitation searches, and generally involve dileptons orjets
plus missing ET signals.
The signatures are expected to be spectacular, and detector
performances are probably less crucial than elsewhere.
All this is very, very, very speculative. But it's probably the most
ground-breaking discovery LHC/SLHC can possibly make.
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