s - Indico

Transcript

s - Indico

INFN what next
- prima discussione in ALICE -
Andrea Dainese
(INFN Padova, Italy)
Discussione What next, 19.02.14
Andrea Dainese
1
Introduzione
u  What
next: workshop a Roma il 7-8 aprile
u  Discussione
su nuove idee e prospettive per le linee di
ricerca “fondamentale” dell’INFN à studio particelle e
interazioni fondamentali: SM EWSB e QCD, BSM, dark
matter and energy, gravitational waves, vuoto
u  In particolare: quali direzioni prendere se LHC e gli
esperimenti di ricerche varie non trovano niente nei
prossimi 3-4 anni
u  Formati
9 gruppi di lavoro (GdL), trasversali alle
commissioni scientifiche
u  QGP nel gruppo “SM precision measurements (LHC and
beyond)”
Andrea Dainese
2
What next (A. Masiero)
u  What
next intende chiamare i ricercatori e i tecnologi dell’
INFN a rivolgersi la domanda: se nel 2017 non dovessero
emergere indicazioni di nuova fisica al TeV ne’ da LHC14
ne’ dagli esperimenti di ricerca diretta e indiretta di materia
oscura, quali direzioni si possono prendere? E come
procedere nel caso in cui comparissero invece (tenui)
segnali di tale nuova fisica (es. una nuova particella
colorata a 2.5 TeV o un supposto wimp con sez. urto di
10^-11 pb)?
Andrea Dainese
3
What next (A. Masiero)
u  Il “programma” What next si articola in piu’ fasi:
Ø  una prima fase da qui all’ appuntamento del 7-8 aprile serve per
costituire i gruppi di lavoro che metteranno insieme del materiale e
soprattutto delle idee per tracciare il cammino vero e proprio
Ø  l’incontro del 7-8, il kickoff del programma, sara’ il momento per
mettere insieme questo lavoro preparatorio dei vari gruppi di lavoro
Ø  una seconda fase, da aprile fino, grosso modo, alla fine dell’anno, in
cui i WG lavorano veramente sul materiale e sulle idee portate il 7-8
aprile arrivando a delle proposte concrete e a una selezione su quali
convergere
Ø  una terza fase fino alla primavera-estate del 2015 in cui si arrivera’
a compimento del percorso (con un qualche documento finale che
contenga risposte e proposte di fisica e non una lista delle spesa di
tante cose belle che si potrebbero fare).
Andrea Dainese
4
Gruppi di Lavoro
Andrea Dainese
5
Mandato dei GdL – 10 domande
u 
1- Identificazione dei problemi cruciali di fisica nel dato settore.
u 
2 - Analisi del potenziale delle imprese in corso nel dato settore
u 
3- Analisi delle motivazioni teoriche che giustificano l' attesa di
importanti scoperte dalle imprese in corso o previste a medio termine.
u 
4- Che progressi scientifici potrebbero invece essere possibili in questo
settore a 10, 20 o piu' anni da adesso?
u 
5- Qual' sarebbe la rilevanza di imprese a lungo termine in questo
settore nel contesto complessivo della fisica delle particelle elementari.
Andrea Dainese
6
Mandato dei GdL – 10 domande
u 
6- Quali sono i limiti oggettivi delle tecniche esistenti (i.e. limite del
fondo di neutrini nella ricerca di DM)
u 
7- Quali potrebbero essere invece la sensibilità e nuovi limiti intrinseci di
potenziali nuove misure a medio/lungo termine in questo campo?
u 
8- Ci sono misure in campi affini o tecniche sperimentali alternative che
possono dare risultati complementari o migliorare quelli ottenibili nei
modi usuali? (es. Assioni, CMB..)
u 
9 - Quali sono le infrastrutture di ricerca, sia esistenti che
future, adatte/necessarie per ottenere i migliori risultati?
u 
10 - Quali progressi tecnologici sono necessari per realizzare le
nuove infrastrutture o rivelatori di nuova generazione? (i.e. rivelatori
direzionali per DM)
Andrea Dainese
7
GdL – Misure precisione SM
Possibile sviluppo a lungo termine
u  EWSB (Higgs)
Ø  HighLumi LHC (2025-2035)
Ø  Linear collider (ILC, CLIC) (~2030?)
Ø  Future Circular collider (pp, ee, ep) >2035?
u  QCD/QGP
Ø  “HighLumi-HI” LHC (2020-2028)
Ø  Fixed target al CERN? CBM a FAIR?
Ø  FCC-ions (AA, pA, eA) >2035?
Andrea Dainese
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Preparazione contributo a What next
u  Prossimo passo: coinvolgere teorici
Ø  Becattini, Beraudo, Greco, Lombardo, Nardi, Polosa, Ratti, …
u  Una
riunione / tavola rotonda ?
u  Quando?
5 o 6 marzo, oppure settimana 17 marzo (troppo
tardi?)
Andrea Dainese
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Prospettive QCD/QGP
u  “HighLumi-HI” LHC (2020-2028)
Ø  Materiale upgrade LOI, TDR, etc…
Ø  Ma necessaria discussione critica di quali sono i punti principali che
vogliamo enfatizzare, una buona occasione per discutere anche di
possibilità non considerate, insieme con i teorici italiani
u  Fixed
target al CERN?
Ø  AFTER@LHC, proposta in preparazione per esperimento a
bersaglio fisso con fasci p e A di LHC (beam-halo); coinvolgimento
Torino (Enrico, Roberta)
Ø  Misura dileptoni a SPS à Gianluca
u  CBM
a FAIR?
Ø  Invitare Alberica?
u  FCC-ions
(AA, pA, eA) >2035?
Ø  Kickoff meeting settimana scorsa, gruppo di lavoro heavy ion
Andrea Dainese
10
AFTER@LHC
u  Centre
of mass energy: pp 115 GeV, PbPb 72 GeV
u  The main proposed measurements are:
Ø  measurements of heavy quark, quarkonium and photon production
in proton-proton and proton-nucleus collisions, which address both
the production mechanisms of these particles and the partonic
structure of protons and nuclei;
Ø  measurements that address the nucleon-spin structure using
polarized targets;
Ø  measurements of the modification of heavy quark and quarkonium
production (and other “probes”) induced by Quark-Gluon Plasma
formation in nucleus-nucleus collisions.
u  The
main advantages with respect to collider experiments,
are the high interaction rate and the possibility to change
easily the p+A or Pb+A collision type using targets with
different mass numbers (A) and polarized targets
Andrea Dainese
11
Future Circular Collider Study - SCOPE
CDR and cost review for the next ESU (2018)
Forming an international
collaboration to study:
• pp-collider (FCC-hh)
 defining infrastructure
requirements
~16 T  100 TeV pp in 100 km
~20 T  100 TeV pp in 80 km
• e+e- collider (FCC-ee) as
potential intermediate step
• p-e (FCC-he) option
• 80-100 km infrastructure
in Geneva area
Future Circular Collider Study
Michael Benedikt
FCC
Kick-Off
2014
Discussione
What
next,
19.02.14
Andrea Dainese
5
12
International
collaboration
process
in 2014
Main areas
of FCC design
study
Proposal
for next
Accelerators
and steps:Technologies
Physics
• Suggestions
and comments
from
international community
and
infrastructure
R&D
activities
experiments
discussion
on study contents,
organisation and resources
conceptual
designs
planning
detectors
• Invitation of non-committing expressions of interest for contributions
from
worldwide
Hadron
collider institutes by end May 2014
Hadron coll. physics
High-field magnets
• conceptual
Prepare for
formation
of
International
Collaboration
Board
(ICB);
design
experiments
proposed date first meeting 9-11 September 2014,interface,
to start integration
FCC study
Superconducting
Lepton collider
RF (EOI)
systems
expressions
of interest
conceptual
design
kick-off
event
discussions
Hadron and
lepton
Marchinjectors
April May
iterations
Cryogenics
June
July
1st
e+proposed
e- coll. physics
ICB
meeting
experiments
interface, integration
August September 2014
e- - p physics,
Safety, operation,
Process
be moderatedSpecific
by preparation
group (possibly
extended –
technologies
energy can
management
experiments,
environmental
following
EOI)aspects
until global collaboration is formed and
an international
Interface,
integration
team is put in place to conduct the further study
Infrastructure
Planning
Process remains open, further joining possible …
Michael Benedikt
FCC
Kick-Off
2014
Discussione
What
next,
19.02.14
Andrea Dainese
17
7
13
FCC Kick-Off & Study Preparation Team
Future Circular Colliders - Conceptual Design Study
Study coordination, M. Benedikt, F. Zimmermann
Hadron
collider
D. Schulte
Hadron
injectors
B. Goddard
e+ e- collider
and injectors
J. Wenninger
Infrastructure,
cost estimates
P. Lebrun
e- p option
Integration aspects O. Brüning
Operation aspects,
energy efficiency, safety, environment P. Collier
Technology
High Field
Magnets
L. Bottura
Superconducting RF
E. Jensen
Cryogenics
L. Tavian
Specific
Technologies
JM. Jimenez
Physics and
experiments
Hadrons
A. Ball,
F. Gianotti,
M. Mangano
e+ eA. Blondel
J. Ellis, P. Janot
e- p
M. Klein
Planning (Implementation roadmap, financial planning, reporting)
F. Sonnemann, J. Gutleber
Michael Benedikt
FCC
Kick-Off
2014
Discussione
What
next,
19.02.14
Andrea Dainese
18
14
Proposal for FCC Study Time Line
2014
Q1
Q2
Q3
2015
Q4
Q1
Q2
Q3
2016
Q4
Q1
Q2
Q3
2017
Q4
Q1
Q2
Q3
2018
Q4
Q1
Q2
Q3
Q4
Kick-off, collaboration forming,
study plan and organisation
Ph 1: Explore options
“weak interaction”
Prepare
Workshop & Review identification of baseline
Ph 2: Conceptual study of
baseline “strong interact.”
Workshop & Review, cost model,
LHC results  study re-scoping?
Ph 3: Study
consolidation
4 large FCC Workshops
distributed over
participating regions
Michael Benedikt
FCC
Kick-Off
2014
Discussione
What
next,
19.02.14
Workshop & Review
 contents of CDR
Report
Release CDR & Workshop on next steps
Andrea Dainese
22
15
Work outline - I
Main physics goals
High-precision studies
may require dedicated
experiments
FCC-hh may be a very versatile facility
à  room for ideas for experiments of
different type (collider, fixed target),
size and scope (precise measurements,
dedicated searches, …)
More in Michelangelo’s talk
F. Gianotti, FCC kick-off meeting, 13/2/2014
16
Andrea Dainese
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“CMS + 2x LHCb”
Andrea Dainese
18
Introduction, organization
u  A
discussion group on “Ions at the FCC” started: coordinated
by A.D., S. Masciocchi, U. Wiedemann
Ø  Sub-group of “FHC Physics, Experiments, Detectors”
u  Two
meetings up now, Dec 16-17 and Jan 29
Ø  https://indico.cern.ch/conferenceDisplay.py?ovw=True&confId=288576
Ø  https://indico.cern.ch/conferenceDisplay.py?confId=290413
u  Particip.
from CERN acc. team, theory, ALICE, ATLAS, CMS
u  Goal: explore opportunities with HI at the FCC
Ø  Saturation (contacts: N. Armesto, M. van Leeuwen)
Ø  Soft physics (contact: U. Wiedemann)
Ø  Hard probes (contacts: A. Dainese, C. Roland, C. Salgado)
Ø  γγ / UPC (contact: D. d’Enterria)
u  Work
in progress! Just few initial ideas presented here
Andrea Dainese
19
Ions at FCC: energies and luminosities
u  Centre-of-mass
sNN
Z1Z 2
=
s pp
A1 A2
energy per nucleon-nucleon collision:
sPbPb = 39 TeV
s pPb = 63 TeV
for
s pp = 100 TeV
u  First
(conservative) estimates of luminosity (in comparison
with LHC): x5 larger Lint per month of running
see talk by M. Schaumann
u  Possibility
to increase Lint using nuclei with slightly smaller Z?
Ø  Some of the limiting factors (e.m. process) go with “large” powers of Z
u  Could
(optimistically) aim for programme of 100/nb (LHC x10)
Andrea Dainese
20
High-density QCD in the initial state:
Saturation at low x
u  Explore
new unknown regime of QCD: when gluons are
numerous enough (low-x) & extended enough (low-Q2) to
overlap à Saturation, Non-linear PDF evolution
Enhanced in nuclei: more gluons per unit transverse area
Saturation
scale:
2
Ag(x,Q
1/3
2
1/ 3
2
1/ 3 1
S)
~
A
QS ~
~
A
g(x,Q
)
~
A
S
2/3
πA
xλ
(
se
y
)
λ
(λ~0.3)
Saturation affects process with Q2<QS2
Explore saturation region:
€
à decrease x (larger √s, larger y)
à increase A
Andrea Dainese
21
Kinematic coverage Q2 vs. x: pA FCC
Goals:
•  determine Q2sat
•  test non-linear evolution
Z, W
Perturbative probes (J/ψ, …)
y@LHC y@FCC
Charm
>4
>2
Andrea Dainese
22
22
Quark-Gluon Plasma studies at FCC
t @fmêcD Hydrodynamic freeze-out curves
time
(S. Flörchinger)
time
System
evolution
15
Pb-Pb 5.5 TeV
10
Pb-Pb 39 TeV
5
size
Pb
Pb
0
size
0
2
4
6
8
10
12
14
r @fmD
Properties of QGP:
u  QGP volume increases strongly
u  QGP lifetime increases
u  Collective phenomena enhanced (better tests of QGP transport)
u  Initial temperature higher
u  Equilibration times reduced
Andrea Dainese
23
Quark-Gluon Plasma studies at FCC
Questions to be addressed in future studies include:
u  Larger
Higher
Temp.
Higher
energy
number of degrees of freedom in QGP at
FCC energy?
à g+u+d+s+charm ?
u  Changes in the quarkonium spectra? does Y(1S)
melt at FCC?
u  How do studies of collective flow profit from higher
multiplicity and stronger expansion? More stringent
constraints on transport properties such as shear
viscosity or other properties not accessible at the LHC
u  Hard probes are sensitive to medium properties. At
FCC, longer in-medium path length and new, rarer
probes become accessible. How can both features be
exploited?
Andrea Dainese
24
QGP studies at the FCC:
global properties
u  Extrapolation
to 39 TeV: increase wrt LHC 5.5 TeV
dNch/dη x 1.8
Volume x1.8
Andrea Dainese
dET/dη x2.2
25
QGP studies at the FCC: temperature
u  Temperature
FCC?
from S-B equation
T (τ ) = 4 ε (τ )
u  20%
30
π 2 nd.o. f .
larger for the same
time
LHC
Ø  E.g. 360 MeV at 1 fm/c
u  Initial
time (QGP formation time)?
Ø  Usually ~0.1 fm/c for LHC
Ø  Could be smaller at FCC
u  Significantly
larger initial
temperature? Could reach
close to 1 GeV?
Andrea Dainese
26
Charmed QGP? Secondary/thermal charm?
u 
u 
Expect abundant production of c-cbar
pairs in the medium
Calculations for LHC 5.5TeV: + 15-45%
wrt hard scattering
J. Uphoff et al. PRC82 (2010)
Ø  To be repeated for 39 TeV, could become
comparable with initial production
u 
Should show up as “thermalized”
component at 1-2 GeV
u 
Secondary charm yield very sensitive to
the initial temperature and to the
temperature evolution
dNcc/dy
Ø  Need very precise reference in pp and pA
collisions
B.-W. Zhang et al. PRC77 (2008)
Ø  E.g. factor 2 difference between T0 = 700 and
750 MeV
à Unique opportunity at FCC
Andrea Dainese
27
Charmed QGP?
Equation of state and charm deconfinement
u 
If charm is produced abundantly
during the equilibration of the
medium, this should show up in the
equation of state
P T 4 ~ ε T 4 ∝ nd.o.f
u 
Could verify the lattice QCD
prediction that charm
deconfinement occurs at ~1.5 TC
~250 MeV, e.g. by fitting charm
yields with resonance gas model
g+u+d+s+c
Preliminary!
g+u+d+s
strange
charm
S. Borsanyi et al., arXiv:1204.0995
Andrea Dainese
28
Y(1S) melting at the FCC
u  Sequential
quarkonium melting
(according to binding energy), one of
the most direct probes of
deconfinement
u  Indication of sequential melting at
LHC, but…
u  Y(1S) RAA~0.5: consistent with
suppression of higher states only
u  Y(1S) expected to melt at ~350 MeV
Digal,Petrecki,Satz PRD64(2001)
confirmed by recent calculations, e.g.
Miao, Mócsy, Petreczky, NPA (2011)
à  May
not melt at LHC
à  Full quarkonium melting at FCC
Andrea Dainese
~350 MeV
29
FCC: a new set of Hard Probes
u  The
current LHC heavy ion programme shows that it is
possible to reconstruct HEP-like observables in HI collisions
Ø  Jets, b-jets, Z0, W, γ-jet correlations …
u  HI
performance in future detectors should reach the pp
performance level of current LHC detectors
u  The large cross section and luminosity of the FCC will allow
tagging more complex decay topologies to isolate defined
initial state parton configurations and their propagation in
the medium
Ø  Probe the earliest phases of the collision
Ø  Defined parton configurations traversing the medium
o  e.g Z0+n-jets, top quarks in tt → + − + bb + E
T
Andrea Dainese
30
Hard probes cross sections: LHCàFCC
Computed for pp with MCFM (Campbell, Ellis, Williams, http://mcfm.fnal.gov)
σ(√s)
σ(√s) / σ(5.5 TeV)
u  Larger
increases for larger masses:
Ø 80x for top
Ø 20x for Z0 + 1 Jet(pT>50 GeV)
Ø 8x for bottom or Z0
Andrea Dainese
31
An interesting physics case: boosted color singlets in the medium
Basic idea: the QCD medium does not affect colored objects
smaller than its resolving power Λ
q-qbar with small opening angle;
seen as color-singlet by the medium,
no interaction expected
Medium induces decoherence,
opening angle increases à energy
loss of color-octet’s in the medium
à Boosted color singlet states can be used to probe the
medium opacity / density at different time scales
Armesto, Casalderrey, Iancu, Ma, Mehtar-Tani, Salgado, Tywoniuk 2010-2014
Andrea Dainese
32
An interesting physics case: boosted color singlets in the medium
First estimation of the timescales
for boosted objects in the medium
tt → bb +  + 2 jets + ET
time
t
i
m
e
à Interaction with the medium starts
A tool to probe timescale of medium evolution?
Andrea Dainese
33
Top quarks in Pb-Pb at HL-LHC and FCC
u  tt decay channels:
Ø 10% bb +  + ET observation channel
Ø 44% bb +  + 2 jets + ET
Ø 46% bb + 4 jets
Pb
Pb
u  Estimate
for observation channel in CMS (CMS PAS-FTR-2013-025)
à  ~500 events for 10 nb-1 Pb-Pb 5.5 TeV (“HL-LHC”)
u  FCC: with 100 nb-1, x800 more wrt HL-LHC
à  FCC with CMS-like setup, ~4x105 for “observation channel”
•  could be 4-5x more in the other channels (but higher background)
à  few
103 with pT > 0.5 TeV
à  few 102 with pT > 1 TeV
Andrea Dainese
34
High-multiplicity events in small systems
u 
u 
One of the most interesting findings of the LHC HI programme: similarity of
long-range correlations (ridge) in high-mult pp, pPb as in Pb-Pb collisions
Similar mechanism? Collectivity in small high-density systems? Initial or
final state collectivity?
pp, high mult
CMS, JHEP 1009 (2010) 091
u 
pPb, high mult
CMS, PLB 724 (2013) 213
pPb, high mult
ALICE, PLB726 (2013) 164
Increased energy and luminosity of FCC could be a unique opportunity to
explore more extreme multiplicities and study QCD mechanisms that lead
to thermalization/collectivity
Andrea Dainese
35
High-multiplicity events in small systems
u 
u 
One of the most interesting findings of the LHC HI programme: similarity of
long-range correlations (ridge) J.
in Grosse-Oetringhaus
high-mult pp, pPb as in Pb-Pb collisions
Similar mechanism? Collectivity in small high-density systems? Initial or
final state collectivity?
pp, high mult
pPb, high mult
pPb, high mult
LHCàFCC
CMS, JHEP 1009 (2010) 091
u 
CMS, PLB 724 (2013) 213
ALICE, PLB726 (2013) 164
Increased energy and luminosity of FCC could be a unique opportunity to
explore more extreme multiplicities and study QCD mechanisms that lead
to thermalization/collectivity
Andrea Dainese
36
EXTRA SLIDES ON FCC
Andrea Dainese
37
Outline
u  Introduction,
u  Future
u  Ions
organization
timeline with heavy ions at the LHC
at the FCC
u  High-density
QCD in the initial state: small-x and saturation
QCD in the final state: deconfinement and QGP
u  High-multiplicity
u  γγ
events in small systems (pp, pA)
collisions in a AA collider and connections to cosmic rays
u  Summary
Andrea Dainese
38
Timeline of future HI running at the LHC
Experiments request/goal:
u  Run
2 (LS1àLS2): Pb-Pb ~1/nb or more, at √sNN ~ 5.1 TeV
u  LS2: major ALICE and LHCb upgrades, important upgrades
for ATLAS and CMS, LHC collimator upgrades
u  Run 3 + Run 4: Pb-Pb >10/nb, at √sNN ~ 5.5 TeV
u  pp reference and p-Pb in both Runs 2 and 3-4
Andrea Dainese
39
Outline
u  Future
u  Ions
organization
at the FCC
u  γγ
u  Summary
Andrea Dainese
40
Kinematic coverage Q2 vs. x: pre-LHC
Q2sat,p(x)
A1/3
Andrea Dainese
41
41
Nuclear modification of PDFs
u  Lack
of data at x<10-3
à large spread for nuclear modification of gluons at small scales and x
à DGLAP analysis at NLO shows large uncertainties
≈
measured
expected if no nuclear effects
Andrea Dainese
42
Testing non-linear evolution
u  Cover
significant range in (x, Q2) à next slides
u  Multiple observables with sensitivity to quarks and gluons
Ø  At FCC expect significant charm contribution in sea (see J. Rojo)
u  Kinematics
is cleanest for partonic observables: photons,
Drell-Yan, W/Z bosons
Ø  + no interactions in the final state
u  Hadronic
observables potentially very interesting (e.g.
forward pion+jets)
Ø  Validation and sensitivity will come from LHC data (including
possible impact of final-state effects in pA)
Plan: quantify impact of observables on nuclear PDF fits;
expect constructive overlaps with ongoing LHC studies
Andrea Dainese
43
43
For illustration: Drell-Yan in p-Pb at LHC
Pseudo-data (CMS acceptance)
sea
gluon
Plan: perform similar studies to
assess sensitivity of FCC
Armesto et al., 1309.5371
Andrea Dainese
44
44
Kinematic coverage Q2 vs. x: pA LHC
Andrea Dainese
45
45
Andrea Dainese
46
46
Goals:
•  determine Q2sat
•  test non-linear evolution
Non-Linear evolution for
Q2 < Q2sat
Low Q2:
initial conditions
Andrea Dainese
47
47
Kinematic coverage Q2 vs. x: eA FCC
pA at FCC:
unique access down to
x<10-6 with perturbative
probes
eA at FCC:
down to x<10-5 with
perturbative probes, but
fully constrained parton
kinematics
Perturbative probes (J/ψ, …)
à see also B. Cole in ep/eA session
Andrea Dainese
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48
Outline
u  Future
u  Ions
organization
at the FCC
u  γγ
u  Summary
Andrea Dainese
49
High-density QCD in the final state: the Quark Gluon Plasma
high temperature
high energy density
low baryonic density
Pb
Pb
ε T 4 ∝ nd.o.f
nd.o.f. : 3 → ~40
u 
u 
Lattice QCD predicts phase
transition at Tc~170 MeV
à Quark-Gluon Plasma
Confinement is removed
u 
u 
Partonic degrees of freedom
Unique opportunity to study in the
laboratory spatially-extended multiparticle QCD system
Andrea Dainese
50
Outline
u  Future
u  Ions
organization
at the FCC
u  γγ
u  Summary
Andrea Dainese
51
γ-induced collisions at FCC (Pb-Pb)
u 
u 
Electromagnetic ultra-peripheral collisions (UPC): bmin>RA+RB
HE ions generate strong EM fields from coherent emission of Z=82 p's:
photon-proton,nucleus colls.
=
photon-photon collisions
+
γ
γ
γ
u 
Huge photon fluxes:
Ø  σ(γ-Pb) ~ Z2 (~104 for Pb) larger than in pp
Ø  σ(γ-γ) ~ Z4 (~5·107 for PbPb) larger than in pp
u 
Max. FCC γγ, γN √s energies:
PbPb: √sγγ ~ 1.2 TeV √sγPb ~ 7 TeV
pPb: √sγγ ~ 6 TeV √sγp ~ 10 TeV
Andrea Dainese
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γ-Pb physics at FCC (Pb-Pb)
u  Sensitive
to very small x gluon density: powerful handle on
saturation region with perturbative probes
Q-Qbar: x ~ m2QQ/sγp,γPb~ 10-7 ~2 orders of magnitude
below LHC!
u  Also: inclusive dijet, heavy-Q (also t-tbar)
u  Exclusive
Andrea Dainese
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■ “Low
γγ physics at FCC (Pb-Pb)
masses”: x4 higher effective lumi than at LHC-5.5 TeV
Huge stats for: γγ → γγ , double vector meson (γγ → ρρ, J/ψJ/ψ, ϒϒ),...
■ High masses : x400 more lumi than LHC for Higgs
x700 more lumi than LHC for W+W- (anomalous QGC)
FCC
NHiggs ~ 20 counts/month
LHC
NW+W-~ 1000 counts/month
Nt-tbar~ 20 counts/month
Andrea Dainese
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Cosmic-rays MC tuning with FCC (Pb-Pb)
p,Fe+Air
collisions
Pre-LHC models
tuned here
FCC
LHC
data
ankle
GZK
cut-off
×103
extrapolation
√sGZK~300 TeV
×10 extrapolation
FCC pA and AA probe ankle-energy and provides strong
constraints for hadronic Monte Carlos for UHECR (p,Fe+Air)
Andrea Dainese
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Summary and Outlook
u  Group
formed to discuss heavy ions at the FCC
u  Saturation
physics in pA, eA and γA
Ø  Higher energy and large nuclei à unique access to saturation
region (down to x<10-6) with perturbative probes
u  QGP
physics
Ø  Larger initial temperature and volume entail potentially unique
aspects, e.g. thermal production of charm
Ø  Larger √s and Lint à new hard observables, e.g. top, sensitive to
early stages and time evolution of the medium
u  Plus:
EW physics with γγ and benefit for UHECR studies
Andrea Dainese
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EXTRA SLIDES
Andrea Dainese
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HI-HL-LHC Programme
u 
(not exh
austive!)
Jets: characterization of energy loss mechanism both as a testing ground for
the multi-particle aspects of QCD and as a probe of the medium density
Ø  Differential studies of jets, b-jets, di-jets, γ/Z-jet at very high pT (focus of ATLAS and CMS)
Ø  Flavour-dependent in-medium fragmentation functions (focus of ALICE)
u 
Heavy flavour: characterization of mass dependence of energy loss, HQ in-
medium thermalization and hadronization, as a probe of the medium
transport properties
Ø  Low-pT production and elliptic flow of several HF hadron species (focus of ALICE)
Ø  B and b-jets (focus of ATLAS and CMS)
u 
Quarkonium: precision study of quarkonium dissociation pattern and
regeneration, as probes of deconfinement and of the medium temperature
Ø  Low-pT charmonia and elliptic flow (focus of ALICE)
Ø  Multi-differential studies of Υ states (focus of ATLAS and CMS)
u 
Low-mass di-leptons: thermal radiation γ (à e+e-) to map temperature
during system evolution; modification of ρ meson spectral function as a
probe of the chiral symmetry restoration Ø  (Very) low-pT and low-mass di-electrons and di-muons (ALICE)
Andrea Dainese
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Saturation scale
u  Onset
of non-linear QCD when gluons are numerous
enough (low-x) & extended enough (low-Q2) to overlap:
Q2
~1/Q
Saturation
scale:
€
1
2
2
2/3
⋅
Ag(x,Q
)
~
π
R
~
π
A
A
Q2
gluon
“area”
number
of gluons
nuclear overlap
2
Ag(x,Q
1/3
2
1/ 3
2
1/ 3 1
S)
~
A
QS ~
~
A
g(x,Q
)
~
A
S
πA 2 / 3
xλ
(
se
y
)
λ
(λ~0.3)
Saturation affects process with Q2<QS2
Explore saturation region:
€
à decrease x (larger √s, larger y)
à increase A
Andrea Dainese
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Saturation: possible observables
Sensitivity
"
Observable
"
Initial condition
Evolution
Charged single inclusive at fixed rapidity,
HF: glue
yes
"
pT dependence
DY, photons: sea and glue
yes
pT dependence
Rapidity/energy evolution of single inclusive
yes
yes
Back-to-back correlations (charged,
photons, jets,…): central-central, forwardforward
yes
pT dependence
Back-to-back correlations: central-forward
(charged, photons, jets,…)
yes
yes
Ridge
yes
???
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
…
"
Andrea Dainese
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60
Hydro simulation at FCC
t @fmêcD Hydrodynamic freeze-out curves
time
(S. Flörchinger)
time
System
evolution
15
Pb-Pb 5.5 TeV
10
Pb-Pb 39 TeV
5
size
0
size
0
2
4
6
8
10
12
14
r @fmD
•  Hydro-simulation (b=0, eta/s = 1/4pi, dNch/dy 3600 @ FCC) without
•  initial fluctuations.
•  In the simulation, the difference between FHC and LHC results from
adjusting the initial temperature in the same geometry such that the final
charged multiplicity increases to 3600 (instead of 1600 at LHC).
•  The arrows along the curves indicate the direction and strength of flow
Andrea Dainese
61
Y(1S) melting at the FCC
Miao, Mócsy, Petreczky, NPA (2011)
Andrea Dainese
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Andrea Dainese
63
Andrea Dainese
64
Top quark projection (FCC)
u  ttbar
cross section x80 from 5.5 to 39 TeV
u  With Lint=100/nb, x800 top wrt 10/[email protected]
à  With a detector similar to CMS, we have ~4x105 in the
“observation (cleanest) channel”
Top cross section drops by 2 (3.5)
orders of magnitude at pT = 0.5 (1) TeV
u 
à few 103 with pT > 0.5 TeV
à few 102 with pT > 1 TeV
M.Mangano, FHC informal meeting Nov 2013
Andrea Dainese
65

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