LHeC に向けて

LHeC に向けて
protons
protons
antiprotons
protons
electrons?
ＫＥＫ徳宿克夫
2008年1月12日
12/Jan/2008
1
HERA:
(27.5 GeV e vs 920GeV p)
nuclei
LHeC
(70GeV e vs 7000GeV p)
proton
LHeC
12/Jan/2008
2
歴史
• “Deep Inelastic Electron-Nucleon Scattering at the LHC”
J.B. Dainton, M. Klein, P. Newman, E. Perez, F. Willeke
JINST 1 (2006) P10001
• DIS2006 (つくば）： J. Daintonのトーク
• 2006 ＡｄｖｉｓｏｒｙＣｏｍｍｉｔｔｅｅが組織
• 2007 ＳｔｅｅｒｉｎｇＧｒｏｕｐ結成 10月26日初会合
• 2007年11月30日 Open ECFA ミーティングでの発表（Ｍ．Ｋｌｅｉｎ）
ECFA, CERNのサポートが得られる。
• ＷＧ結成に向けて、Ｃｏｎｖｅｎｏｒの人選中。 2008年9月にCERN近辺で
ワークショップ。
• 2009年末にＣＤＲ
ep と pp が同時に実験できるオプション以外はない。
電子加速器を建設する機会はLHCアップグレードのときのみ
12/Jan/2008
3
Inclusive Kinematics for 70 GeV x 7 TeV
s  1.4 TeV
W  1.4 TeV
7
x  10 at
New physics, distance
Q 2  1 GeV2
scales few . 10-20 m
High precision
partons in LHC
plateau
High
Density
Matter
12/Jan/2008
Low x
parton
dynamics
Large x
partons
• High mass
(Q2) frontier
• Q2 lever-arm
at moderate x
• Low x (high W)
frontier
4
●たとえば、leptoquark
レプトンとクォークがあるなら、その両方の
性質をもった粒子もあっていいのでは？
LHC 対生成
LHeC もともとある
クォークとレプトンから作れる
Re
+ resonance
LHCで発見された後、LHeCで狙いを定めて精密測定
12/Jan/2008
5
対生成の断面積は、QCD： αs とマスで決まる。
Eqだと断面積はそのe-q-LQ結合の強さに
よる。
Sensitivityは残念ながら、LHCよりそう
優れているわけではない。
12/Jan/2008
6
しかし、見つかったあとで、LQの
性質を調べるのには LHeCは
非常に有効
F = +1
+
e,
q
e+
_
q or q ?
Asymmetry
F = -1
LHC: single prod. 100 fb-1
LHeC: 10 fb-1 per charge
 = 0.1
e-
_
q or q ?
12/Jan/2008
7
Inclusive Kinematics for 70 GeV x 7 TeV
New physics, distance
scales few . 10-20 m
Large x
partons
High precision
partons in LHC
plateau
High
Density
Matter
12/Jan/2008
Low x
parton
dynamics
s  1.4 TeV
W  1.4 TeV
7
x  10 at
Q 2  1 GeV2
• High mass
(Q2) frontier
• Q2 lever-arm
at moderate x
• Low x (high W)
frontier
8
Event Rates: Ee x 7000 GeV
Neutral Currents
electrons
positrons
Charged Currents
100 fb-1 70 GeV
10 fb-1 140 GeV
12/Jan/2008
2 times Ee compensates for 10 times the energy at highest Q2
9
High x Partons と as
Full NC/CC sim (with systs)
& NLO DGLAP fit …
… high x pdfs  LHC discovery
& interpretation of new states?
… projected as precision few/mil
(c.f. 1-2% now)
12/Jan/2008
10
Heavy Quarks
bottom
High precision c, b measurements
(modern Si trackers, beam
spot 15 * 35 m2 , increased
rates at larger scales).
Systematics at 10% level
beauty is a low x observable!
s (& sbar) from charged current
LHeC 10o acceptance
strange
LHeC 1o acceptance
(A. Mehta, M. Klein)
(Assumes 1 fb-1 and
- 50% beauty, 10%
charm efficiency
- 1% uds  c
mistag probability.
- 10% c  b mistag)
12/Jan/2008
11
Impact of CTEQ6.5M,S,C PDF’s on stot’s at LHC
12
W, Z production :
really standard candles?
+
Wu-Ki Tung @ DIS2007
Useful general results: LHC Luminosities
Yuan: EW
Cteq6.5 err. band
CTEQ 6.1 -> 6.5:
Difference in HQ
treatment：
Cteq6.1 err. band
MZ
MW
D ~7%,
(outside error band)
12/Jan/2008
Through the global fitting of PDF,
→ change in Gluon
→ change in Sea quark
Change in W-production @ LHC
LHC data help to improve PDF.
12
SUSYのパラメータ領域では、
陽子の中のb-クォーク分布が大きく効く場合もある。
―> SUSYパラメータの決定の上でも、重要になってくる可能性がある。
Higgs
<-SM
MSSM->
12/Jan/2008
13
Low x MachineとしてのLHeC
HERAからさらにlow-x
へ拡張できる。
INCREDIBLE
LOW x
COVERAGE!
ただし実験的には
非常に難しい。
電子のエネルギーが
高いために、LowQ2では
散乱角が非常に小さい。
179度 ―> Q2＝1GeV2
ただしルミノシティーは
たいしていらない。
Saturationに答えを出せる
（か？）
12/Jan/2008
14
HERA の場合
Gluck, Reya
and Vogt
“pQCD” : parton evolution
1
0
Fixed
target
data
Early ZEUS data showed rapid
increase of F2 at low x.
“Hadronic”: Regge theory
12/Jan/2008
behavior of γp total cross section15
Donnachie & Landshoff
F2 構造関数の測定
• xが小さくなるとF2 は急激に大きくなる
– 陽子の中にはsoft ‘sea’ クォークがたくさん
ある
• Q2 が大きくなるにつれてその傾きは急
になっている。
softer parton
resol.
smaller
dynamics of quarks and gluons
• 高いxでは低エネルギーのデータとよく
つながっている。
• DGLAP発展方程式を使ったNLOQCD
はデータを非常に良く再現できている。
12/Jan/2008
16
12/Jan/2008
17
LHeC の場合 : どのSaturation模型か？
Forshaw, Sandapen, Shaw
hep-ph/0411337,0608161
FS04 Regge (~FKS): 2 pomeron model, no saturation
FS04 Satn: Simple implementation of saturation
CGC: Colour Glass Condensate version of saturation
12/Jan/2008
18
Saturation model 毎の
違いを議論できるか？
―>もっとStudyが必要
!! eAも可能 !!
J. Forshow,
P. Newmann
12/Jan/2008
19
どうやって LHeC を実現するか
ep と pp が同時に実験できるオプション以外はない。
電子加速器を建設する機会はLHCアップグレードのときのみ
LINAC-RING
RING-RING
• Previously considered as `QCD
explorer’ (also THERA)
• First considered (as LEPxLHC)
in 1984 ECFA workshop
• Reconsideration (Chattopadhyay
& Zimmermann) with CW cavities began
• Recent detailed re-evaluation
with new e ring (Willeke)
• Main advantages: low interference
with LHC, Ee  140 GeV, LC relation
• Main advantage: high peak
lumi obtainable (1033 cm-2 s-1)
• Main difficulty: peak luminosity only
32 cm-2 s-1 at reasonable power
~0.5.10
12/Jan/2008
• Main difficulties: building it
around existing LHC, e beam life 20
Ring-Ring
Parameters
• LHC fixes p beam parameters
Top view
• 70 GeV electron beam, (compromise
energy v synchrotron  50 MW)
• Match e & p beam shapes, sizes
Non-colliding p beam
Vertically displaced
• Fast separation of beams with
tolerable synchrotron power
requires finite crossing angle
• 2 mrad angle gives 8s separation at
first parasitic crossing
2 mrad
• High luminosity running requires low b
focusing quadrupoles close to interaction
point (1.2 m)  acceptance limitation to 10o of beampipe
12/Jan/2008
21
Ring-Ring Design
• e ring would have to bypass experiments and P3 and 6
• ep/eA
interaction region could be in P2 or P8.
12/Jan/2008
22
Linac-Ring Design
(70 GeV electron beam at
23 MV/m is 3km + gaps)
6km
alternative sites
S. Chattopadhyay (Cockcroft), F.Zimmermann (CERN), et al.
Relatively low peak lumi, but good average lumi
Energy recovery in CW mode (else prohibitive power usage)
12/Jan/2008
23
Comparison Linac-Ring and Ring-Ring
Energy / GeV
40-140
Luminosity / 1032 cm-2 s-1
0.5
Mean Luminosity, relative
2
Lepton Polarisation
Tunnel / km
Biggest challenge
Biggest limitation
IR
Plenary ECFA, LHeC, Max Klein,
CERN 30.11.2007
60-80%
6
CW cavities
luminosity (ERL,CW)
not considered yet
one design? (eRHIC)
40-80
10
1 [dump at L peak /e]
30% [?]
2.5=0.5 * 5 bypasses
Civil Engineering
Ring+Rf installation
maximum energy
allows ep+pp
2 configurations [lox, hiq]
e±p Luminosity
Ring-ring
Linac-ring
Timeline
● 2007: form working groups + steering committee
initial meeting of conveners + committee
SAC overview
● 2007/8: ECFA/CERN endorsement “work out”
● 2008: workshop I
● 2009: workshop II
LHeC CDR [LHC Committee]
● 2011: LHeC TDR
- construction 8 years ?
- impact on LHC: civil engineering + installation
e-ring and e-linac
- be aware of CLIC progress
12/Jan/2008
26
Scientific Advisory Committee (SAC)
Accelerator Experts
S.Chattopadhyay, R.Garoby, S.Myers, A. Skrinsky, F.Willeke
Research Directors
J.Engelen (CERN), R.Heuer (DESY), Y-K.Kim (Fermilab), P.Bond (BNL)
Theorists
G.Altarelli, S.Brodsky, J.Ellis, L.Lipatov, F. Wilczek
Experimentalists
A.Caldwell (chair), J.Dainton, J.Feltesse, R.Horisberger, A.Levy, R.Milner
12/Jan/2008
27
Steering Group
Oliver Bruening
(CERN)
John Dainton
(Cockcroft)
Albert DeRoeck
(CERN)
Stefano Forte
(Milano)
Max Klein - chair (Liverpool)
Paul Newman (Birmingham)
Emmanuelle Perez (CERN)
Wesley Smith
(Wisconsin)
Bernd Surrow
(MIT)
Katsuo Tokushuku
(KEK)
Urs Wiedemann
(CERN)
+ (increasing)
12/Jan/2008
28
Working Group Structure
•Accelerator Design [RR and LR]
•Interaction Region and Forward Detectors
•Infrastructure
•Detector Design
•New Physics at Large Scales
•Precision QCD and Electroweak Interactions
•Physics at High Parton Densities [small x and eA]
Convenors 候補者にコンタクトを
取っているところ
―> ぜひ参加を
12/Jan/2008
29
 pn  3.8m
Luminosity: Ring-Ring
N p  1.7 1011
N p
Ie
I
m
L

 8.310 32  e
cm2 s1
4e pn b pxb py
50mA b pxb pn
s p( x,y )  s e(x,y )
b px  1.8m
b py  0.5m
4
P 100GeV 
Ie  0.35mA
 

MW
E


e


 Ie = 100 mA
1033
likely klystron
installation limit
Synchrotron rad!
1033 can be reached in RR
Ee = 40-80 GeV & P = 5-60 MW.
HERA was 1-4 1031 cm-2 s-1
huge gain with SLHC p beam
F.Willeke in hep-ex/0603016:
Design of interaction region
for 1033 : 50 MW, 70 GeV
May reach 1034 with ERL in
bypasses, or/and reduce power.
R&D performed at BNL/eRHIC
Plenary ECFA, LHeC, Max Klein,
CERN 30.11.2007
cf also A.Verdier 1990, E.Keil 1986
Luminosity: Linac-Ring
 pn  3.8m
P
P / MW
N p
32
2 1
L


110

cm
s
*
4e pnb E e
E e /GeV

N p  1.7 1011
b *  0.15m
Ie 100mA

 Ie = 100 mA
LHeC as Linac-Ring version
 can be as luminous as HERA II:
High cryo load to CW cavities
s  2TeV

Plenary ECFA, LHeC, Max Klein,
CERN 30.11.2007
P GeV

MW E e
4 1031 can be reached with LR:
Ee = 40-140 GeV & P=20-60 MW
LR: average lumi close to peak
140 GeV at 23 MV/m is 6km +gaps
Luminosity horizon: high power:
ERL (2 Linacs?)

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