overview of future colliders - texas a&m...

Overview of Future Colliders

Hongbo ZhuInstitute of High Energy Physics, Beijing

IX International Conference on Interconnections between Particle Physics and Cosmology (PPC2015), June 29th - July 3rd 2015, Deadwood, South Dakota

Overview of Future Colliders, H. ZhuInstitute of High Energy Physics

Colliders over the Decays

2

V D Shiltsev, “High energy particle colliders: past 20 years, next 20 years and beyond”, Physics-Uspekhi 55 (10) 965-976 (2012)


Outline

• Future colliders‣ ILC/CLIC‣CEPC-SPPC‣FCC‣HL-LHC

• Physics programs

• Summary

3

CEPC-SPPC (50 km)

FCC (80 km)

(HL-)LHC (27 km)

ILC (31 km) /CLIC (48 km)

B-factories, muon collider, gamma-gamma collider and several other colliders are also very interesting but not discussed here.


International Linear Collider (ILC)

• e+e- linear collider with Superconducting RF linac

• Baseline: √s = 500 GeV (31 km) → upgrade later to ~ √s= 1 TeV (50 km), luminosity of 1.8 × 1034 cm-2 s-1 with optional upgrade, one interaction point (IP) with two detectors: ILD and SiD with push-pull

4


ILC History• Pre-ILC (several linear collider concepts since early 90s), technology

decision in 2004 → SCRF‣ TESLA (SCRF)‣ NLC/JLC (normal conducting)‣ CLIC (two beam)

• ILC since 2005‣ Global Design Effort founded‣ Reference Design Report (2007)‣ Technical Design Report (2013)

• Current status‣ Linear Collider Collaboration (LCC)‣ ILC: Higgs/top factory → possible realisation in Japan‣ CLIC: multi-TeV option on longer time scale

5

RDR (2007)

TESLA TDR (2001)

TDR (2013)

Waiting for the final decision from the Japanese government by the end of 2015


Compact Linear Collider (CLIC)

• Multi-TeV e+e- linear collider based on high gradient normal-conducting cavities with novel RF power generation (two-beam acceleration), nominal center-of-mass energy of 3 TeV

• Project not as advanced as ILC, possible “Next Big Thing” at CERN?

6

Drive Beam

Main Beam


After the Higgs Discovery

7

Courtesy of Symmetry MagazineA bouquet of options: Higgs factory ideas bloom


Circular Colliders

• The relative lightness of the discovered Higgs boson makes the circular electron-positron machine technologically feasible as “Higgs Factory”.

• A. Blondel and F. Zimmerman “A High Luminosity e+e- Collider in the LHC tunnel to study the Higgs Boson”, arXiv:1112.2518 → LEP3

‣ Super-TRISTAN, Fermilab Site-Filler, CHF, TLEP

8

• ICFA Beam Dynamics Workshop, Accelerators for a Higgs Factory: Linear vs. Circular (HF2012) → circular machines under “official” discussion

• ICFA 2013 statement:Factory

ICFA Beam Dynamics Workshop

Accelerators for a Higgs Factory:

Linear vs. CircularNovember 14-16, 2012Fermilab, Batavia, Illinois, U.S.A.

conferences.fnal.gov/hf2012γγ

Organizing Committee:Alain Blondel, U.of GenevaAlex Chao, SLACWeiren Chou, Fermilab, ChairJie Gao, IHEPDaniel Schulte, CERNKaoru Yokoya, KEK

Local Committee:Elliott McCrory, FermilabCynthia Sazama, FermilabTanja Waltrip, FermilabSuzanne Weber, Fermilab

Contact:Cynthia M. Sazama, Conference OfficeFermi National Accelerator LaboratoryM.S. 113, P.O. Box 500 Batavia, IL 60510, U.S.A.Fax: +1-630-840-8589 E-mail: [email protected]

“ICFA supports studies of energy frontier circular colliders and encourages global coordination.”

FCC� hh, ee, heCEPC-SPPC


Circular Electron Positron Collider (CEPC)

• Circular e+e- collider with “conventional” accelerator technologies proposed by the Chinese HEP community in 2012

• Baseline design: √s = 240 GeV (54 km), single ring with the pretzel scheme, luminosity of 2 × 1034 cm-2 s-1 @ 240 GeV, 2 IP’s; 10 years of data-taking

• Optional to operate at other energies: 91 GeV (Z-pole) and 160 GeV (WW)

9

BTC�

IP1�

IP3�

e+� e-�

e+ e- Linac

LTB�

CEPC Collider Ring�

CEPC Booster�

BTC�


Machine Layout

10


Possible Project Timeline

• Preliminary Conceptual Design Reports reviewed by international review committees and released:

‣ Volume I: Physics and Detector

‣ Volume II: Accelerator

11

2015�

2020�

2025�

2030�

2035�

R&D Engineering Design

(2016-2020)�

Construction (2021-2027)�

Data taking (2028-2035)�

Pre-studies (2013-2015)

1st Milestone: pre-CDR (by the end of 2014) → R&D funding request to Chinese government in 2015 (China’s 13th Five-Year Plan 2016-2020) �

CEPC�

CEPC-SPPCPreliminary Conceptual Design Report

Volume I - Physics & Detector

The CEPC-SPPC Study Group

March 2015

IHEP-CEPC-DR-2015-001

IHEP-EP-2015-01

IHEP-TH-2015-01

IHEP-CEPC-DR-2015-01

IHEP-AC-2015-01

CEPC-SPPC Preliminary Conceptual Design Report

Volume II - Accelerator

The CEPC-SPPC Study Group

March 2015

Available on the CEPC website:http://cepc.ihep.ac.cn/preCDR/volume.html

http://cepc.ihep.ac.cn/preCDR/volume.html


Detector Design Concept

• Feasibility studies based on the ILD-like detector concept, with modifications to the interaction region (IR) to cope with much shorter final focal length (L*)

‣ Final focusing magnets inside the detector → constraints on detector layout and technology choice + backgrounds from backscattering particles

• Detector performance requirements (similar to ILC):

• Additional critical challenges:

‣ Detector/electronics power consumption (too short bunch crossing, power-pulsing not optional)

‣ Detector backgrounds → detector occupancy, radiation damage, DAQ …12


Super Proton-Proton Collider (SPPC)

• pp collider after the electron machine in the same tunnel → LEP-LHC model

• “Baseline design”: √s = 70 - 100 TeV, luminosity of 1035 cm-2 s-1 (different opinions on the required luminosity), 2 interaction points

• Main constraint: high field superconducting magnets, e.g. dipole magnets:

‣ 50 km: B = 20 T, E = 70 TeV

13

SPP ME Booster

SPPC LE Booster

IP4� IP2�

SPPC Collider Ring�

Proton Linac

SPPC HE Booster

min0

2 ( )BBC

π ρ=


High Field Superconducting Magnets

14

Nb3Sn + HTS�

2015 – 2020 � •  Develop 12 T Nb3Sn double-aperture dipole magnet •  Conduct basic technology research on HTS materials and wires

and prototype an inserted coil of 2 – 3 T�

2020 – 2025� •  Develop 15 T Nb3Sn double-aperture dipole/quadruple magnets •  Conduct basic technology research on HTS materials and wires

and prototype an inserted coil of 4 – 5 T�

2025 – 2030� •  Develop Nb3Sn (15 T) + HTS (5 T) or HTS (20 T) dipole magnet

2030 – 2035� •  Knowledge and experience transfer to industry, enabling mass production

R&D for 20 years


Possible Project Timeline

15

2015�

2020�

2025�

2030�

2035�

R&D Engineering Design

(2016-2020)�



Pre-studies (2013-2015)

1st Milestone: pre-CDR (by the end of 2014) → R&D funding request to Chinese government in 2015 (China’s 13th Five-Year Plan 2016-2020) �

CEPC�20

20�

� � � � 2030�

2040�

�

R&D (2014-2030)�

Engineering Design (2030-2035)�



SppC�

• Extremely tight schedule, close to unrealistic

• Possibility to operate both electron and proton machines at the same time to accumulate more Higgs events


Civil Engineering

• Detailed geological survey and conceptual design efforts of civil engineering, summarised in preCDR volume III: Civil Engineering (only in Chinese)

16

IHEP

proton electron


Future Circular Collider (FCC)

• 100 TeV proton-proton (and heavy-ion) collider and a high luminosity e+e- collider (H, Z, W and tt̄) as a potential intermediate step

17

FCC-hh LHCEnergy [TeV] 100 14Dipole field [T] 16 8.33# IP 2 + 2 4Luminosity [cm-2s-1] 5-25× 1034 1× 1034

Stored energy/beam [GJ] 8.4 0.39Synchrotron rad. [W/m/aperture]

28.4 0.17Bunch spacing [ns] 25 (5) 25

FCC� hh, ee, he

Overview of Future Colliders, H. ZhuInstitute of High Energy Physics 18

M. Benedikt, “FCC study overview and status” in FCC Week 2015


High Luminosity LHC

• HL-LHC expected around 2023 to 5-7 ×1034 cm-2s-1 and to deliver an integrated luminosity of 3000 fb-1 to each experiment over 10 years

• ATLAS/CMS detectors to be upgraded/re-built to cope with the hash collision conditions yet to maintain/enhance the performance

21

European Strategy:

P5 Report:


Physics Programs (selected topics)

22


e+e- Colliders: Luminosity vs Energy

23


Higgs Measurements

• Well-defined initial states → model independent measurements

• Recoil mass method: reconstructed the Z decay without touching the Higgs, allowing precision measurements: production cross sections, branching ratios, Higgs mass, total decay width and more …

24

M2

recoil

= (ps� Eff )2 � p2ff = s� 2Eff

ps+m2

ff

dominant process at √s ~ 240 GeV


Higgs Couplings

• Higgs couplings to fermions and gauge bosons predicted by the Standard Model (SM): and ; deviations from the SM couplings parameterised as:

25

f = g(hff)g(hff ;SM) ,V = g(hV V )

g(hV V ;SM)

g(hff ; SM) g(hV V ; SM)

LHC 300/3000 fb-1

CEPC 250 GeV at 5 ab-1 wi/wo HL-LHC

κb κc κg κW κτ κZ κγ10-3

10-2

0.1

1

RelativeError

Precision of Higgs couplingmeasurement (Contrained Fit)

ILC 250+500 GeV at 250+500 fb-1 wi/wo HL-LHC

CEPC 250 GeV at 5 ab-1 wi/wo HL-LHC

κb κc κg κW κτ κZ κγ κμ Br(inv) κΓ10-3

10-2

0.1

1

RelativeError

Precision of Higgs couplingmeasurement (Model-IndependentFit)

Model-dependent fit: Model-independent fit:


Expected Precision

26


Higgs Self-coupling

• Critical parameter governing the dynamics of electroweak symmetry breaking; accessible via the loop correction to the hZ production @CEPC:

27

��Zh = �Zh

�SMZh

� 1 = 2�Z + 0.014��hhh


EW Precision Measurements

• EW precision measurements with significantly reduced uncertainties:

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RLdt � 150 fb�1

Rb, AbFB , sin ✓

effW ,mZ ,mW , N⌫ · · ·


Electroweak Oblique Parameter Fit

• Electroweak parameters S and T, describing the gauge boson self-energies, are sensitive to physics beyond the Standard Model.

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-0.2 -0.1 0.0 0.1 0.2-0.2

-0.1

0.0

0.1

0.2

S

T

Electroweak Fit: S and T Oblique Parameters

Current (95%)Current (68%)CEPC (95%)CEPC (68%)

-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

S

T


Current (68%)CEPC baseline (68%)Improved ΓZ (68%)

-0.04 -0.02 0.00 0.02 0.04-0.04

-0.02

0.00

0.02

0.04

S

T


CEPC baseline (68%)Improved ΓZ (68%)

Improved ΓZ, mt (68%)


Higher Energies

• Precise determination of the top mass ( ) with the threshold scan method (350 GeV reachable at FCC-ee/ILC/CLIC )

• Top-Higgs Yukawa coupling (500 GeV) accessible at ILC/CLIC with expected precision of and Higgs-self coupling via

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�gt/gt = 10%

�mt ⇠ 100 MeV

e+e� ! tt̄h


ILC/CEPC/FCC Complementary

• Higgs coupling measurements: considerable improvement in precision for bb, gg, cc, WW, 𝝉+𝝉- and 𝞒tot ,+ top-Higgs coupling, top mass by ILC

• Accelerator technologies (e.g. RF cavity) and detector technologies (vertex detector, calorimeter, etc. ) → important to exploit the synergies

31

ILC 250+350+500 GeV with 500+200+500 fb-1CEPC 250 GeV with 5000 fb-1ILC + CEPC


[TeV]g~m0 2 4 6 8 10 12

[TeV

]0 1χ∼

m

0

2

4

6

8

10

12

-1100 TeV, 3000 fb-133 TeV, 3000 fb-114 TeV, 3000 fb

-114 TeV, 300 fb

01

χ∼qq01

χ∼qq→g~g~→pp discoveryσ5

Physics@100 TeV

• Physics opportunities: Naturalness, Dark Matter, EW phase transition … → much extended searches with unprecedented high energy

32Waiting for more results/hints from the LHC

gluino-neutralino with LF decays

[TeV]g~m0 2 4 6

[TeV

]0 1χ∼

m

0

2

4

6-1100 TeV, 140 PU, 3000 fb

-133 TeV, 140 PU, 3000 fb-114 TeV, 140 PU, 3000 fb

-114 TeV, 50 PU, 300 fb

01

χ∼tt01

χ∼t t→g~g~→pp discoveryσ5

gluino-neutralino with HF decays


Summary

• ILC/CLIC, CEPC-SPPC and FCC: extraordinary physics potential → precision measurements + search for New Physics

• Important to exploit the synergies between different projects (accelerator/detector/computing and more) → Global Efforts

33

CEPC-SPPC (50 km)

FCC (80 km)

(HL-)LHC (27 km)

ILC (31 km) /CLIC (48 km)


Extra Slides

34


Cross-sections

35

e−

e+

Z∗

Z

H

e−

e+e+

Z∗

Z∗

e−

H

e−

ν̄ee+

W ∗

W ∗

νe

H

dominant process at the threshold


CEPC-SPPC PreCDR International Reviews

36

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