Physics news and open questions

ECFA@Valencia

Gudrid Moortgat-Pick (IPPP, Durham)

General remarks

Physics case for polarized positrons

can be compensated by higher electron polarization?

what happens if only 30%, but almost 'for free'?

status of the submitted POWER report

Some further news

Questions of the parameter groups to the physics groups

new webpages for (polarized) ILC positron sources

Summary and open questions for the discussion

General remarks

Expected: e- polarization of about 90% ....... won't such high P(e-) suffice?

Polarimeter precision: x = ∆Pe- / Pe-= 0.5% ( 0.25%)

Technical issues for the baseline design:

e+ source: helical undulator with 100 m length

provides automatically low but stable polarization (about 30%)

no spin rotators from LTR in baseline included

low dc polarization, has to be measured

Suitable beam polarization of e- and e+

crucial to get a direct access to particle properties (couplings, quan. num., etc.)

'compensates' missing lumi (higher rates, control of sys. and backgrd., etc.)

How much do we gain from 30% polarization?

Successful ILC physics requires high lumi and polarized beams

Statistics -- gain in Peff and ALR

For many processes (V, A interactions) the cross section is given by:

(Pe- Pe+) = (1- Pe- Pe+ ) 0 [1- Peff ALR] with Peff = (Pe- - Pe+) / (1 - Pe- Pe+ )

(80%,60): Peff = 95% (90%,60%): Peff =97% (90%, 30%): Peff =94 %

ALR/ALR = 0.3

gain: factor~3 factor>3 factor~2 NO gain with only polarized e- ! ( error prop.: )

Peff /%

~∆ ALR /ALR

ALR/ALR = 0.27

ALR/ALR =0.5





Example -- Determination of top couplings

Process: e+ e- t t (test of couplings t , Z unique for the ILC)

Studies at threshold: since ∆ ALR / ALR ~ ∆ Peff / Peff

and with only

(80%,0) (80%,30%): factor 2

since again left-right asymmetry decisive: with (80%,30%) a factor 2 expected

Beam polarization for Higgs searches

Light Higgs, e.g. mH=130 GeV: HZ and H  similar rates at 500 GeV

P(e-), P(e+) needed for:

separation

background suppression

(H Z) /  (H ):

(+80%,0) (+80%,-60%)

improves by factor 4!

(+80%, -30%) 0.14 1.06

(+80%,0) (+80%, -30%): ratio HZ / H   gain ~ factor 2

(-80%, +30%) 2.34 1.42

Test of SUSY quantum numbers

Association of chiral electrons to scalar partners and :

s-channel t-channel

1. separation of scattering versus annihilation channel

2. test of 'chirality': only survives at P(e-) > 0 and P(e+) > 0 !

(90%,60%)~200 fb / 50 fb ~ 4 , (90%, 30%)~ 175 fb / 75 fb ~ 2.3

Even high P(e-) not sufficient, P(e+) is substantial!

Indirect searches: extra dimensions

Transversely polarized beams (only effects detectable of P(e-) and P(e+) !)

enables to exploit azimuthal asymmetries !

Distinction between SM and different models of extra dimension:

asymmetry signals contribution from spin-2 graviton

Since PT(e-) x PT(e+)-dependence:

effects decrease by about a factor 2 when using (80%,30%) instead of (80%60%)

Transversely polarized beams very effective, need polarized e- and e+ !

High precision tests at GigaZ

Measurement of sin2eff in e+e- Z f f :

usually ∆ P/ P ~ 0.5% sufficient (maybe ∆ P/ P~ 0.25% reachable !)

with and P(e-)=80% only:

with Blondel scheme: [ P(e-),P(e+) ]= [80%,60%] :

[80%,30%] : about a factor 2 worse

∆ P/ P ~ 0.5%

Sensitivity to high scales at GigaZ

Maybe quick upgrade path straight from 500 GeV to GigaZ needed?

study worst (?) case scenario: no SUSY hints at LHC, none at ILC500 ....

help from GigaZ possible? concentrate on energy upgrade? or what else?

Arne

Weber, Georg Weiglein

GigaZ may be crucial to outline needed higher energy scale for ILC, 2nd stage ....

SM-value in '~decoupling' limit

current exp. value

SUSY prediction depending

on mass scale of EW SUSY particles

Sensitivity to SUSY effects even if no SUSY signal seen at LHC and ILC500!

Summary table of POWER report: Tab 4.1

Comparison with (80%,0): estimated gain factor when

most (80%, 60%) (80%, 30%)

gain factor 2

factor 1.3 worse

PTe- PTe+ required

gain factor 1.4

gain factor 2

gain factor 1.6

PTe- PTe+ required

Summary table of POWER report: Tab 4.1

Estimated gain factor when only P(e+)=30%

Pe+ required

factor <2 worse

Summary table of POWER report: Tab 4.1

Estimated gain factor when only P(e+)=30%

Physics case for pol e+ established:
`The role of polarized positrons and electrons in revealing fundamental interactions at the Linear Collider'

GMP et al., hep-ph/0507011, submitted to Physics Reports

also available via http://www.ippp.dur.ac.uk/~gudrid/power

Excellent and detailed referee report obtained: thanks to the referee!

more introductory remarks for physics studies; clarification of some studies

references missing

some plots have to be improved

already under work, but not yet finished: authors will then be contacted

Further agreement with editor: since some updates on physics and machine are available during the meantime

recent results on top physics, experiments E166 and ATF etc. will be included for revised/published version

Question of the parameter group – our answers ?

At which lumi become systematics dominant?

Impact of reducing beamstrahlung by factor 2? (lumi vs background?)

Any benefit from (80%,60%) versus (90%,0)?

Influence from any other accelerator parameters?

Top mass measurement: precision at a) threshold, b) 500 GeV? P(e+) needed

Higgs (120 GeV): Precision for mass measurement at a) threshold, b) maximum of ZH cross section, c) 500 GeV ? factor 4 vs 2 in sep.

Precision for top Higgs coupling at a) 500 GeV, b) 1 TeV ? gain factor 2.4 vs. 1.1

Precision of BR(H -> tau-pairs) ?

Precision of Z' couplings at a) 500 GeV, b) 1 TeV ? systematics under control

Precision of SUSY particle properties (e.g. masses) a) in the light stau coannihilation region, b) light neutralino 01, 02 production ? more observables

properties more general: P(e+) needed

Further news: 'e+ sources' webpage series

Idea: provide data base for 'sources' and 'non-sources' experts

cover all ILC sources

list all agreed facts and numbers

publications (e.g. POWER report, executive summary + 4 pages summary !)

provide useful links

all new results should be listed there as soon as possible ....please let me know!

Pages should cover topics from source to IP

all possible technologies

target issues

related topics, e.g. damping rings, reliability etc.

list of open questions and topics

prototypes and current R&D status: many activities at Cornell, KEK, Orsay, UK !

Please look at:http://www.ippp.dur.ac.uk/~gudrid/source

ILC Positron source group

ILC Positron Source Group:

`Detailed positron system designs and documentation are required for ILC TDR at the end of 2009. It is important to organize the international activities so that essential work is accomplished and unnecessary duplication is reduced. The group meets three times a year, rotating Europe-Japan-America. '

First meeting at Oxford, September 2006

John Sheppard elected at spokesman of the collaboration

Planned: second meeting in China, Jan. 31st – Feb. 2nd (chaired by M. Kuriki)

Registration for the 'ILC Positron Source Group' email list:

Summary and ......

Physics case for pol. e+ has been established !!! (-> POWER report + ....)

referee report now available, but revised version still under work

Baseline design could already provide 30% polarization

already very constructive for physics

Quick upgrade path to GigaZ might be very crucial to outline needed energy upgrade

high lumi and pol. beams needed to optimize physics at 500 GeV !!!

However, to use such low polarization 'for free' still needed:

spin rotator for LTR, low enery polarimeter and kickers

New 'ILC e+ sources' webpages: input needed, please provide news if available

ILC Positron Source Group: registration for email list open

2nd meeting: begin of February in China

Discussion (thanks to Mike Woods, Eric Torrence, Peter Schmid, Tom Rizzo, .... )

Physics: shall we also write / answer to the questions of the parameter group?

even higher e- pol. can not compensate effects from pol. e+ .....

Physics: shall we write-up the physics case for pol. e+ with P(e+)=30%?

Machine: what is needed to exploit 30% polarization?

how much low dc polarization without spin rotators? (Mike: ~0.05% .... but has to be measured)

spin rotator for LTR

already flipping needed ? which scheme useful? kickers?

costs for add. polarimeter? but anyway needed to measure low dc polarization?

Machine: change request useful to exploit 30%?

What else? Did we overlook something?

General remarks about the coupling structure

Which configurations are possible in annihilation channels?

contributions from LR, RL: SM and(?) NP (, Z)

contributions only from LL, RR: NP !

Which configurations are possible in scattering channels?

depends on P(e+)!

helicity of e- not coupled

with helicity of e+ !

depends on P(e-) !

direct access to new physics particle properties: new effects

(general (V-A) structure, e.g. top physics; Peff decisive)

ATLAS - ID Commissioning

2003-03-07T10:03:06

SPS/PS Coordinator