Status of LC physics study group in Japan (I)

LC Physics Study Meeting

March 6 (Sun), 2005

Nobuchika Okada (KEK)

Japanese LC Physics Study Group

http://www-jlc.kek.jp/subg/physics/

a mixture of experimentalists and theorists mainly working in Japan.

Subgroups

Higgs, New Physics, Top, Gamma-Gamma (ee–option), Luminosity

Higgs subgroup activities and related works

Higgs physics at LC

Higgs boson EW symmetry breaking

mass generation mechanism

Measurement of Higgs boson mass and self coupling

structure of EW symmetry breaking

New physics if

Priority ⇒ Higgs Physics at TeV LC

1.Higgs self coupling⇒ We started (from 2002)

2.Top Yukawa3.Heavy Higgs, etc.

etc..

etc..

Studies on Higgs self coupling measurement

by Y. Yasui and S. Yamashita

Assumption No bkg effects 100% signal efficiency

by Yasui et.al.

@@LCWS '02 Jeju KoreaLCWS '02 Jeju Korea

LCWS’04 Paris France Quick Simulation (includes bkg.) study!!

dominant for E

CM > 1TeV

Ecm = 1 TeV

main mode W-fusion

Higgs mass = 120 GeV

SM decay Br

ISR/BSR included

Signal & bkg event generator

LCGrace (BASES+SPRING)

Signal MC: X + hh

/SM from 0.0 to 2.0 with 0.2

step

Smearing simulation at parton level

Jet energy resolution ~ 30%/√E (GeV)

(detector R&D target value)

Simulation StudySimulation Study

ννhh quick analyses

only for hh decaying to 4b

Br(hh4b) ~ 47 %

for 120 GeV SM Higgs

Signal characteristics

Large missing energy, missing PtOnly 4 b jetsM1 jj ~ Mh M2 jj ~ Mh

No isolated lepton

Signal and Background processesSignal and Background processes

Signal(for SM)

Main bkg processes 4b + missing

ννbbbb (~ ννZZ, ννZγ*)

ννbbh

(~ ννZh)

By LCGrace

1. Likelihood selection bkg further reduction

2. Separate Zhh & fusion different dependence (positive/negative interferences)

3. Combine with Zhh analyses for s-channel process

4. Check hh invariant mass

5. hhh

measurements

ννhh Analysis Flowννhh Analysis Flow

dep. of cross-section

νeνehh

Zhh

/SM

L = 1 ab-1

ννbbbb

ννbbh =SM

=

Reconstructed ‘Higgs’ mass

ννbbbb

Likelihood

ννbbh

ννhh

=

=SM

coun

ts

L = 1 ab-1

ννhh selection

(~ OPAL Higgs scheme)(~ OPAL Higgs scheme)

Missing mass [GeV]

‘Zhh’

‘fusion’

ννhh channel

coun

ts

Separate Zhh & fusion

(= visible mass)

‘fusion-channel’

hh invariant mass [GeV]co

unts

ννhh

=

=SM

hh invariant mass [GeV]

coun

ts

‘Zhh-channel’

Zhh=SM

=2 SM

HH invariant mass distributionsHH invariant mass distributionsHH invariant mass distributionsHH invariant mass distributions

Mh=120 GeV

Mea

sure

d / S

M

True /SM

95%CL upper bound

95%CL lower bound

67%CL range

Ilumi=1 ab-1

Pol beam= -80%

@1TeV

Mh=120 GeV(SM Higgs Br)

Use only hh4b(Br(hh4b)~47%)

Eff.(4b) 80%

By Yamashita et.al. LCWS 2004

hhh Measurement sensitivityhhh Measurement sensitivity

Precise study Radiative corrections are also important!! Systematic study of the RC for Higgs physics at LC with GRACE

Higgs coupling constants as a probe of new physics

S. Kanemura, S. Kiyoura, Y. Okada, E. Senaha, C.-P.Yuan, PLB558(2003)157.S. Kanemura, Y. Okada, E. Senaha, C.-P. Yuan, PRD70(2004)115002.

Z

h

Z

h

h

h

t

t

Higgs coupling constants as a probe of new physics

Top loop effects (SM)

Z

h

Z

hh

h

Φ

Φ

S. Kanemura, S. Kiyoura, Y. Okada, E. Senaha, C.-P Yuan

Allowed region of the deviation from the SM of the hZZ and hhh coupling

(M = 0 case )

δ= 0 　 corresponds to the decoupling limit ； sin(β － α) 　＝１

hZZ ⇒ 　　 deviation mainly comes from the tree-level mixing effect (radiative correction － 1%)

hhh ⇒　　 the tree-level mixing effect　 O(10%) radiative correction 　 O(+100)%　　　　　　 due to the non-decoupling loop effect

S. Kanemura, Y.Okada, E. Senaha, C.-P. Yuan

Connection between collider physics and cosmology

Electroweak baryogenesis and quantum corrections to the triple Higgs boson coupling

S. Kanemura, Y. Okada, E. Senaha, PLB606(2005)361.

By the non-decoupling loop effect of extra Higgs bosons, the renormalized hhh coupling (h: SM like Higgs boson) in the 2HDM can differ from the SM prediction by O(100%)

Large deviation in hhh due to the non-decoupling effect corresponds to the successful scenario of electroweak baryogenesis

Baryogenesis : C, CP violation 2HDM Out of equilibrium 1st order PT

Sphaleron condition

Spharelon condition

Cubic term can be sufficiently large due to non-decoupling effect of extra Higgs boson loop

Electroweak Baryogenesis and quantum corrections to the triple Higgs boson couplings

S. Kanemura, Y. Okada, E.Senaha

Search for the lepton flavor violating Yukawa interactionvia the Higgs boson decay

S. Kanemura, K. Matsuda, T. Ota, T. Shindou, E. Takasugi, K. Tsumura, PLB599(2004)83,S. Kanemura, T. Ota, K. Tsumura, work in progress.

Search for LFV via the Higgs decay

S. Kanemura, K. Matsuda, T. Ota,

T. Shindou, E. Takasugi, K. Tsumura

Mh=120GeV, L=1ab^-1

LFV Higgs coupling may be measured at LC

Extension to the general 2HDM S. Kanemura, T. Ota, K. Tsumura

Perturbative unitarityVacuum stability

Constraint on parameters: LEP precision data

Similar to the MSSM, but no SUSY relation among Higgs parameters

For the low tanβ region, no constraint on h →μτ 　 from tau rare decay 　 results

Measurement of h→τμ at LC can give strong constraint on κ32 esp for low tanβ 　

Possibility of a fixed target experiment at LC

Search for Lepton Flavor Violating Deep Inelastic Scattering Processes

S. Kanemura, Y. Kuno, M. Kuze, T. Ota, PLB607 (2005) 165.

Alternative process for search of the Higgs LFV coupling.

• At future ν factories (μ colliders) , 10^20 muons of energy 50 GeV (100-500GeV) can be available. DIS μ Ｎ→ τ Ｘ process

• At a LC (Ecm=500GeV L=10^34/cm^2/s)

10^22 of 250GeV electrons available. DIS process e Ｎ→ τ Ｘ process

μ （e） τ

N

qq

h, H, A

X

A fixed target experiment option of LC

Cross section in SUSY model

CTEQ6L

• Each sub-process e q (μq) →τq is proportional to the down-type

quark masses.

• For the energy > 60 GeV, the total cross section

is enhanced due to the b-quark sub-process

E ＝ 50 GeV 10^(-5)fb 100 GeV 　 10^(-4)fb

250 GeV 　 10^(-3)fb

μ （e） τ

N

qq

h, H, A

X

Phenomenology of CP violating Higgs sector in the MSSM

A. Akeroyd, S. Kanemura, Y. Okada, E. Senaha, hep-ph/0409318

A. Akeroyd, S. Kanemura, Y. Okada, E. Senaha

SUSY loop contributions to the W pair production

K. Hagiwara, S. Kanemura, M. Klasen, Y. Umeda, PRD68(2004)1103011.S. Alam, K. Hagiwara, S. Kanemura, Y. Umeda, R. Szalapski, PRD62(2000)095011; NPB541(1999)50.

The one-loop form factors are tested except for

overall renormalization

: Goldstone boson

Gounaris et al

SUSY loop contributions to

• Calculation tested by the – BRS sum rules – Decoupling property

• The typical size of the contributions to M(00)– a few times 0.1 % for sfermion effects – O(1%) for chargino/neutralino effects

• CP phase effect in the chargino/neutralino sector– At most 0.1% in M(0+)

K. Hagiwara, S. Kanemura, Y. Umeda

Sfermion effects

First 2 generation squark effect

Stop-sbottom loop effect

Chargino/neutralino effects

CP phase effect

CP odd form factors F4, F6, F7

New Physics subgroup activities and related works

Collider signal of New Physcs: MSSM, Large extra-dimensions etc.

1) Studies on MSSM

Mass and cross-section measurements of chargino production at LC

by Y. Kato, K. Fujii, T. Kamon, V. Khotilovich, M. M. Nojiri to be published in PLB (hep-ph/0411249)

Chargino pair production process is one of the key

for determination of supersymmetric parameters at LC

If large tan beta

Event:

KK graviton mediated process

Phenomenology of graviton Kaluza-Klein modes

Detection of Extra-dimension @ LC

through KK graviton mediated processes

2) Collider signal of large extra dimensions

Large extra-dimension (ADD) scenario

(Arkani-Hamed-Dimopoulos-Dvali, ’98)

I: total cross section

　　　 new physics evidence

II: angular dependence of cross section

　 effects due to spin 2 particle exchange

Important points:

deviation from the SM collider energy

LC < LHC

precise measurements of angular dependence

LC > LHC

process

KK graviton exchange is dominant

SM background free very interesting

if this cross section is large enough

N. Delerue, K. Fujii & N. Okada

PRD 70, 091701 (2004)

Example:

Comparable to

Characteristic angular dependence of cross section

Reflects spin 2 nature of KK graviton

Invariant mass distributions

Invariant mass distributions

Number of remaining evens per

700 Higgs Pair events @ 1TeV LC

integrated luminosity 500

Essentially No SM backgrounds!

Reconstruction of Angular Distribution (after selection)

integrated luminosity 500

Next example: is now work in progress….

Future plan

• Higgs– SM Higgs/Light Higgs

Study method is already established.

: ~2% accuracy for mh = 120–140 GeV

– Heavy Neutral Higgs in SUSY, 2HDM, etc.

Mass reach is heavier than e+e-

AHee

HA,

eeHA sm 5.0,

eeHA sm 8.0,

pair production

single production

t, b, W, ‥‥

h

γ

γ

subgroup activities and related works

– Heavy Neutral Higgs in SUSY, 2HDM, etc.

(1) Production:

A-H-continuum intreference

Asakawa-Kamoshita-Sugamoto-Watanabe Eur.Phys.J.C14:335(2000)

Large Interference effects !

t

t

t

t－ －

A,H

Comparable around the resonance

(2) Phase of γγΦ: magnitude of the vertex ⇔ 　 Γ(φ→γγ) 　 phase of the vertex ⇔ 　 Observables including interference effects They are sensitive to existence of new charged particles.

arg 0

arg 45

b

b

t tm GeV

even

ts /

GeV

for

Lee=

3fb-

1

2RRM

2LLM

*2 RR LLM M *2 RR LLM M

3tan

400

GeVM A

M

σ

σ

σλ

λσ

λ

λ

Asakawa-Hagiwara Eur.Phys.J.C31.351(2003)

bγ

bγ : γγφ vertex

• Large Extra-dimensions

Collaboration is being groped.

• Tools– GRACE/SUSY/1LOOP-CAIN

Automatic calculation up to 1-loop level in SM&MSSM

with REALISTIC photon luminosity simulations

Basically, has been developed.

Other activities Yasui-san’s talk