motivazioni per collider adronici dopo l’lhc: dall’slhc al vlhc
DESCRIPTION
MOTIVAZIONI PER COLLIDER ADRONICI DOPO L’LHC: DALL’SLHC AL VLHC. Padova, 19 Nov 2003. G.F. Giudice CERN. R. Brock (EXP Fermilab) C. Hill (TH Fermilab) P. Sphicas (EXP Cern) G. Giudice (TH Cern). LHC. Well-motivated energy range. Find the Higgs - PowerPoint PPT PresentationTRANSCRIPT
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MOTIVAZIONI PER COLLIDER ADRONICI DOPO L’LHC: DALL’SLHC AL VLHC
G.F. Giudice
CERN
R. Brock (EXP Fermilab)
C. Hill (TH Fermilab)
P. Sphicas (EXP Cern)
G. Giudice (TH Cern)
Padova, 19 Nov 2003
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LHC
2
22222
2
2 GeV200TeV
4228
3
SM
tHZWSMF
H mmmmG
m
Well-motivated energy range
• Find the Higgs
• Find the physics ultimately responsible for EW breaking
TeVSM
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4
300-450 MCHF (incluso 70 MCHF di Linac4, ma senza rivelatori); 500 MCHF per SPL
~ 2 GCHF
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A. De Roeck
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Qual e’ il futuro dei collider adronici dopo l’LHC?
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VLHC ParametersStage 1 Stage 2
Total Circumference (km) 233 233
Center-of-Mass Energy (TeV) 40 200
Number of interaction regions 2 2
Peak luminosity (cm-2s-1) 1 x 1034 2.0 x 1034
Dipole field at collision energy (T) 2 11.2
Average arc bend radius (km) 35.0 35.0
Initial Number of Protons per Bunch 2.6 x 1010 5.4 x 109
Bunch Spacing (ns) 18.8 18.8
* at collision (m) 0.3 0.5
Free space in the interaction region (m) ± 20 ± 30
Interactions per bunch crossing at Lpeak 21 55
Debris power per IR (kW) 6 94
Synchrotron radiation power (W/m/beam) 0.03 5.7
Average power use (MW) for collider ring 25 100
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Stage-2 VLHC Conclusions
• The Stage 2 VLHC can reach 200 TeV and 2x1034 or more in the 233 km tunnel.
• A large-circumference ring is a great advantage for the high-energy Stage-2 collider. A small-circumference high-energy VLHC may not be realistic.
• There is the need for magnet and vacuum R&D to demonstrate feasibility and to reduce cost. – This R&D will not be easy, will not be
quick, and will not be cheap.
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VLHC Tunnel Cross Section
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Underground Construction
• Three orientations chosen to get representative geological samples of sites near Fermilab.– South site samples many geologic
strata and the Sandwich fault.– One north site is flat and goes
through many strata.– Other north site is tipped to stay
entirely within the Galena-Platteville dolomite, and is very deep.
• These are not selected sites – merely representative.– Cost of other sites can be built
from data gained in these sites.
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LHC is the machine to study the scale of EW breaking
NEW THEORY
Desert, e.g. conventional susy need for precision
New thresholds around 10 TeV need for energy increase to make next step of discoveries
Multi-TeV linear collider?
VLHC ?
m < TeV measurements after LHC
VLHC not meant to push new-physics limits by an order of magnitude, but to explore a well-motivated
(after some LHC discoveries) energy region
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DESERT
• Connection with GUT, strings, quantum gravity
• Gauge-coupling unification
• Neutrino masses
• Suppression of proton decay and flavour violations
• Setup for cosmology (inflation, baryogenesis)
NON DESERT
• Low-scale string theory,…
• Accelerated running, different sin2W
• R in bulk
• Different location of quarks and leptons in bulk
• Low-scale inflation, EW baryogenesis
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NON-DESERT SCENARIOS offer good motivations for explorations with a √s ~ 100 TeV hadron collider
• Need to test the theory well above the EW breaking scale
• Existence of new thresholds in the 10 TeV region
Not a systematic review, but some examples relevant to VLHC
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GRAVITY IN EXTRA DIMENSIONS
GRAVITY IN EXTRA DIMENSIONSFundamental scale at SM
Any short-distance scale < SM
-1 explained by geometry
42/12/ DMRM DPl
KRPl eMM 5
FLAT Arkani Hamed-Dimopoulos-Dvali
WARPED Randall-Sundrum
20H
QUANTUM GRAVITY AT LHCQUANTUM GRAVITY AT LHC
Graviton emissionMissing energy (flat)
Resonances (warped)
TT
4
1
252
1ff
Contact interactions (loop dominates over tree if gravity is strong)
Higgs-radion mixing
G.G.- Rattazzi - Wells
G.G. - Strumia
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These processes are based on linearized gravity valid at √s <<MD ~TeV
• Suitable for LHC
• VLHC can extend limits, but the motivations are weak
VLHC can probe the region √s >>MD~TeV
(only marginal at LHC)
independent test, crucial to verify gravitational nature of new physics
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TRANSPLANCKIAN REGIME
2
1
3
c
GDP
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1
3
1
1
2
3
2
81
c
sGR DS
Planck length quantum-gravity scale
PSD
PS
RM
R
:slimit kian transplanc
:0 limit classical
Schwarzschild radius
classical gravity
same regime
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b > RS
Non-perturbative, but calculable for b>>RS (weak gravitational field)
Gravitational scattering: two-jet signal at hadron colliders
G.G.-Rattazzi-Wells
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b < RSGiddings-Thomas, Dimopoulos-Landsberg
At b<RS, no longer calculable
Strong indications for black-hole formation
At the LHC, limited space for transplanckian region and quantum-gravity pollution
At the VLHC, perfect conditions
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2-jets with large Minv and Black holes
Jets + missing ET 2-leptons
QUANTUM GRAVITY
Semi-classical approximation
Linearized gravity
Transplanckian
Cisplanckian
VLHC
LHC
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INVESTIGATING THE THEORY OF ELECTROWEAK BREAKING
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5.6
9.2
9.7
4.6
7.3
6.1
4.3
4.5
3.2
6.4
9.3
5.0
12.4
FqdH
bbee
ee
LLHDiH
HDH
BWHH
LuudR
uuL
aa
2
55
2
2
1
LEP1
LEP2
MFV
Bounds on LH
LH > 5-10 TeV
+
O2LH
1L
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SM<1 TeV, LH>5-10 TeV
“Little” hierarchy between SM and LH
•New physics at SM is weakly interacting
•No (sizable) tree-level contributions from new physics at SM
•Strongly-interacting physics can only occur at scales larger than LH
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22222
2
2 GeV200TeV
4228
3
SM
tHZWSMF
H mmmmG
m
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t
mH2 =
H H+
t~
2
2
2
22
~ln2
~3
t
ttF
m
mmG
PROBLEMA DELLA GERARCHIA controllo delle divergenze quadratiche alla massa dell’Higgs
SUPERSIMMETRIA:
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HIGGS AS PSEUDOGOLDSTONE BOSON
HIGGS AS PSEUDOGOLDSTONE BOSON
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/
forbids
symmetry realizedlinearly -Non
:
2
hmahh
ae
fef
ia
fi
Gauge, Yukawa and self-interaction are large non-derivative couplings
Violate global symmetry and introduce quadratic div.
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A less ambitious programme:
Explain only little hierarchy
At SM new physics cancels one-loop power divergences
LITTLE HIGGSLITTLE HIGGS
LH
224
4
22
222
2
TeV10 loops Two
TeV loop One
SMFSM
FH
F
SMSMSMF
H
mGm
Gm
Gm
Gm
“Collective breaking”: many (approximate) global symmetries preserve massless Goldstone bosonℒ1ℒ
2
H2
222
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Hm
ℒ1 ℒ2
Arkani Hamed-Cohen-Georgi
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Realistic models are rather elaborate
Effectively, new particles at the scale f ~ SM
canceling (same-spin) SM one-loop divergences with couplings related by symmetry
Typical spectrum:
Vectorlike charge 2/3 quark
Gauge bosons EW triplet + singlet
Scalars (triplets ?)
Arkani Hamed-Cohen-Georgi-Katz-Nelson-Gregoire-Wacker-Low-Skiba-Smith-Kaplan-Schmaltz-Terning…
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HIGGS AS EXTRA-DIM COMPONENT OF GAUGE FIELD
AM = (A,A5), A5 A5 +∂5 forbids m2A52
gauge HiggsHiggs/gauge unification as graviton/photon unification in Kaluza-Klein
Higgs/gauge unification as graviton/photon unification in Kaluza-Klein
Correct Higgs quantum numbers by projecting out unwanted states with orbifold
Yukawa couplings, quartic couplings without reintroducing quadratic divergences
Csaki-Grojean-Murayama
Burdman-Nomura
Scrucca-Serone-Silvestrini
EW BROKEN BY BOUNDARY CONDITIONS? Csaki-Grojean-Murayama-Pilo-Terning
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Calculable description of EW breaking with strong dynamics at 5-10 TeV
New realizations of technicolour theories with new elements (extra dimensions, AdS/CFT correspondence) allowing some calculability
“Little hierarchy” is satisfied
LHC will discover weak physics at SM
New strong-dynamics thresholds at LH within the reach of VLHC
KKMgN
sRgg
sgN
T
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2500
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96
2
1
192
23 Unitarity
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• The most important requirement for the survival of HEP is worldwide cooperation resulting in a global strategy based on a visionary science roadmap.
• Sell the science, not the instruments– Learn from the NASA strategy, in which the goals are truly large and
visionary, and the instruments are missions along the way.
• The parameters and schedule for a VLHC will depend on the timing and location of all other large facilities. The global plan should recognize these couplings.
• If we ever want to build a VLHC, or any other very large facility, we need to have a vigorous R&D program now.
– The R&D is very challenging, and the penalty for failure will be severe.
P. Limon
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• Anni futuri cruciali per i nuovi progetti di alte energie
• La fisica fondamentale puo’ difendere con orgoglio la sua missione
EXP
• Un grande progetto negli USA necessario per la fisica delle particelle
• R&D sui vari fronti deve proseguire
TH
• Nuove strategie per capire la fisica della rottura EW
• In scenari “non-desert”, forti motivazioni per una nuova scala a ~ 10 TeV VLHC
CONCLUSIONI
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