Physics @ LHC (Physics @ TeV) Status of LHC/ATLAS/CMS and Physics - - PowerPoint PPT Presentation

SLIDE 1

Physics @ LHC

(Physics @ TeV)

Status of LHC/ATLAS/CMS and Physics explored at LHC

Fundamentalist of High Energy Physics (U. Tokyo)

SLIDE 2

Most important/urgent topics in Particle Physics are: (1) Understanding of “the origin of mass” (EW symmetry breaking) SSB of Higgs field is most promising scenario, but should be examined directly & determine the potential: (2) Beyond the Standard Model Supersymmetry is most promising, Large Extra Dimension, unexpected scenario… are also exciting. These two topics are main purpose of LHC project:

[0] Introduction:

SLIDE 3 TOTEM

In 27 km LHC ring, 1232 superconducting dipoles are filled for bending, Magnetic filed is B=8.3 T Two General purpose Detectorｓ ATLAS and CSM PP collider √s=14TeV (effective √s is about several TeV: So LHC is a real TeV collider) Design L=1034cm-2s-1 (100fb-1/year) 1032-1033 for 2008 and 2009

[1] Status of LHC

LHC is PP collider, Anti-p is not used. So there is no problem due to anpi_proton intensity

SLIDE 4

Schedule of LHC

Today Feb. 2007 Dipole Magnet Ready Mar. 2007 Machine and Detectors Ready Aug. 2007 √s=0.9TeV Commissioning Run Nov. 2007 √s=14TeV Physics Run Jun. 2008 End of 2008 L=2-4 fb-1 (SUSY up to 1.5 TeV , many mass region of Higgs, BH) End of 2009 L = O(10) fb-1 (Higgs completely covered, SUSY up to 2TeV) After 2010 Operated with Design Luminosity (100fb-1/year) Detail measurements on Higgs/SUSY/LED/ “SM”

SLIDE 5

[2A] Status of ATLAS Detector

Resolution (Pt=100GeV) e, γ 1.3% Muon 2% Jets 8%

Very Large Detectors: Well balanced performances are expected.

• Accordion Shape of L.Ar detectors for Calorimeters
• Large air-core toroidal magnet for muon system

Key of ATLAS detector

SLIDE 6

Tracking System

Tracking (|eta|<2.5) is composed with

• Si pixels and strips semiconductor
• Transition Radiation Tracker Detector (e-ID)
• 2T solenoid magnet

SLIDE 7

Calorimeter covers to (|eta|<5 ~ 1degree) :

• EM is Pb absorber L. Ar

with accordion shape electrode.

• HAD is Fe/scintillator (central),
• Cu/W-LAr (fwd)

Tile Hadron Calorimeter EM+Magnet Calorimeters

SLIDE 8

Muon system

• Muon Spectrometer (|eta|<2.7) :

air-core toroidal with muon chambers (small E loss, benefit in forward region)

Endcap muon Toroidal Magnet

SLIDE 9

Detector will be ready until the end of this summer muon system with Toroidal

Endcap Calorimeter Barrel region is already installed behind endcap cal.

Detector commissioning has already started using cosmic ray

Tracker calorimeter

Dead Channel: 0.2% SCT Noise hit ~10-4

SLIDE 10

[2B] Status of CMS

HCAL Magnet Tracker Muon chambers ECAL H=15m L=22m (about half of ATLAS) W=12,500ton (twice of ATLAS) There are two key technologies in CMS:

• 4T Solenoid Magnet

(Strong field & Large Volume D=6m 2.7GJ)

• PbWO4 scintillator is used for EM

(good resolution)

Resolution (Pt=100GeV) e, γ 0.9% Muon 2% Jets 12%

SLIDE 11

4T Magnet is ready and cosmic rays(>14M events) are detected in commissioning run:

Delivery of PbWO4 crystals is

• behind. Just Barrel counter is

ready before commissioning run. Endcap EM counters will be installed in 2008. 2 barrel(PbWO4) modules has installed.

SLIDE 12

[3] Origin of Mass (Higgs)

SSB of Higgs Potential gives mass to Gauge boson W/Z: (Freedom of ξ)

Motion in η is corresponding to

Higgs boson Simulated H→γγ events

Higgs boson will be observed at LHC like this event (simulation)

SLIDE 13

[3-1] Production processes of SM Higgs at LHC

Gluon Fusion Vector Boson Fusion Associate production with W/Z

GF & VBF are important for discovery: Cross-section of ttH/bbH is small, but give the direct information of Yukawa yt/yb. Associate production with t/b

4 processes

SLIDE 14

φ

Detector Central (1) Scattered “high Pt” jets are observed in the forward regions. Pt ~ Mw (2) There is rapidity gap between two jets because there is no color exchange. Only the products from Higgs are

• bserved in the central region.

These are very promising signatures in

• rder to suppress the background.

Vector Boson Fusion (1998 Zeppenfeld et al.)

η VBF QCD(color exchange) Number of jets η VBF has an excellent potential because of :

SLIDE 15

[3-2] Decay Branching Fraction

Precision measurements of the SM at LEP suggests M(H)=115-200GeV(95%CL)

H→ bb,tautau,γγ (M(H)<140GeV) H→ ZZ(*),WW(*)

(M(H)>130GeV)

In such a light region, there are 5 important decay modes.

H → γγ Br is small of about 10-3, But promising mode due to good resolution of γ

SLIDE 16

H→γγ γγ+1j H→γγ γγ+0j H→γγ γγ+2j

huge BG. S/N ~1% qq_bar→ γγ is dominante BG is High but also signal stat. is high

Xsection (fb/GeV)

Mγγ(GeV) Mγγ(GeV)

Mγγ(GeV) Xsection (fb/GeV)

γ-ID and resolution are essential :

BG can be estimated with the side band. ATLAS preliminary

Good S/N and flat BG but Stat. limited Xsection (fb/GeV)

[3-3A] H→ γγ in GF and VBF (small Br, but excellent Mγγ）

H→γγ indicates that spin

• f Higgs is 0 (or 2).  scalar

ATLAS preliminary Two leading processes contribute to three different event topologies: S/N and shape of BG are different in 3 class. Discovery potential of them are similar, and we have good redundancy.

SLIDE 17

[3-3B] H→ ZZ(*)→ ４leptons

Resolution and identifications of leptons are excellent. Invariant mass distributions of 4 leptons are shown with BG contributions. Irreducible BG is qq_bar → ZZ* → 4l (continuous distribution) Reducible BGs are tt & Zbb (lepton comes from semileptonic decay of B

B contamination can be suppressed by isolation of track + anti-impact parameter Track quality is essential for this mode )

ZZ*→ 4l has excellent discovery potential except for M(H)<130GeV and M(H)=170GeV (Branching is small):

We can determine also CP, Spin of Higgs using this channel.

CMS Full M(H)=140GeV M(H)=200GeV

SLIDE 18

[3-3C] ＶＢＦ H→ττ

+ hll + ll4

Resolution of mET is about 10GeV  Mtautau has sharp peak (sigma ~ 10GeV) Dominant Background process is Z(→tautau)+Njets. Peak appears at 91GeV.  Resolution and tail of mET distribution are essential for this channel

ATLAS Fast CMS Full Tau decay includes neutrino, but Momenta of ν’s can be calculated using mET information in the collinear limit.  Tau can be reconstructed !!!!

This mode is direct evidence of Higgs- fermion coupling (Yukawa) Origin of fermion mass

SLIDE 19

[3-3D] VBF Ｈ→ WW

MＨ=160GeV

W +W ll

Clear Jacobian Peak is observed: tt → bb lνlν is main BG: Leptons are back-to-back in tt. MT

2 = 2 /

P

TP ..LL (1 cos)

e- W+ W- e+

Higgs Spin0

Leptons are emitted in the same direction

CMS Full ATLAS

Dilepton+mET Φ between di-lepton (Rad)

Leptonic decays of W lead to the event topology of

SLIDE 20

[3-4] Discovery Potential of the SM Higgs

LO calculation NLO calculation

Similar Discovery potentials are obtained at both ATLAS and CMS (Notice LO calculation vs NLO) VBF γγ + exclusive 1,2 jets analyses will gain significance in low mass regions H->γγ, tautau covers the region < 130GeV, WW,ZZ > 130GeV 5sigma discovery is possible with L=10fb-1 for both ATLAS and CMS Different technologies are essential for various modes: (Safe and redundant)

SLIDE 21 ATLAS + CMS preliminary 1 10 10-1

Needed ∫Ldt (fb-1) per experiment

mH (GeV)

≤ 1 fb-1 for 98% C.L. exclusion ≤ 5 fb-1 for 5σ discovery

• ver full allowed mass range
• -- 98% C.L. exclusion

Let’s combine ATLAS+CMS performance 5σ discovery is possible within 2008(>130GeV) or early of 2009(<130GeV)  measurements of mass, coupling, spin 98%CL exclusion (2008) No Higgs model? invisible decay? No resonance? critical test can be performed for “origin of mass”

SLIDE 22

• Yｔ, Yτ 10-15%
• Yb 30-40%
• Gz、5-10%

[3-5] Measurements of Mass & coupling (L=300fb-1)

Relative coupling (Normalized to g(WH))

Mass can be measured with accuracy of 0.1% if M(H)<400GeV.

We can show couplings are proportional to their masses

SLIDE 23

Accuracy of “absolute measurements” of the couplings. We assume the SM branching fractions except for the leading five processes: Br(H->tautau,tt,bb,ZZ and WW) Within this assumption, Couplings of yt、yτ、yb, gZZH and gWWH can be calculated. Accuracy: yt、yτ gZZH and gWWH 20% yb 50%

SLIDE 24

For 6000 fb-1 (SLHC) Δλ ∼ 19% for 170 GeV MH

Higgs Self-couplings

σ×Br is small Need very High Luminosity ー＞SLHC

In order to determine the shape of Higgs potential, Slope of potential is correspond to Self-coupling

SLIDE 25

[4] SuperSymmetry

O(TeV) SUSY provides GUT and good candidate of cold dark matter.

SLIDE 26

[4-1] Production cross-section at LHC

( ˜ g ˜ g , ˜ g ˜ q , ˜ q ˜ q )

˜ g :2TeV ˜ q :2TeV ˜ g :1TeV ˜ q :1TeV

σ~20fb σ~3pb σ~100pb

m(˜ q )= m(˜ g )= 0.5TeV ˜ g ˜ g m(˜ q )= m(˜ g )=1TeV m(˜ q )= m(˜ g )= 2TeV ˜ u ˜ u , ˜ u ˜ d

These couplings are just strong interaction (αs):  large cross-section is expected

model independent except for mass

SLIDE 27

[4-2] Events topology of SUSY (Gravity- mediation + R-parity)

Gluino/squark are produced copiously, Cascade decay is followed. event topologies of SUSY

/ E

T

multi leptons + High PT jets (+ b-jets ) τ-jets

Especially no or one lepton mode is promising for Discovery Many high Pt jets emit in this cascade , Finally nu1 escapes from detection

SLIDE 28

M(˜ g ) ~ M(˜ q ) ~ 1TeV

Count /400GeV/1fb-1

Meff = Pt + mEt

• 0 lepton mode

1 lepton mode Main Background processes are top-pair ,W and Z with jets,

They include high Pt neutrino(s):

QCD jet (with fake mET, due to the limited resolution of detector) also contributes to no-lepton mode (mET performance is crucial for SUSY hunting)  Clear excess can be observed in one-lepton mode & no-lepton mode. High Pt jets are estimated with Matrix Element (ALPGEN 2.05) ME + PS matching is applied:

ATLAS Preliminary ATLAS Preliminary

[4-3] background

OPEN HIST show the SUSY signal Meff distributions after SUSY cut

Meff = Pt + mEt

• L=1fb-1

L=1fb-1

Count /400GeV/1fb-1

(tanβ=10)

SLIDE 29

Number/1fb^-1 mET (GeV) Number/1fb^-1

Opposite Sign dilepton Same Sign dilepton

Almost Background Free

Dilepton mode

 Stat. is limited but excess can be observed also in dilepton mode. Top pair is dominant BG for one-lepton and di-lepton modes.

BG can be estimated with real data easily.

M(˜ g ) ~ M(˜ q ) ~ 0.9TeV

ATLAS Preliminary ATLAS Preliminary

SUSY signal

Red: co-annihilation (light stau) Black: bulk mET (GeV)

SLIDE 30

Background is estimated with “real data itself” (not estimated with MC):

We have good control samples of Z(→ee/mumu)+jets, W(→lν)+jets and tt→bblνqq with MT<MW. From them, the background of Z(→νν),W(→lν), tt with large mET & MT>MW:) can be estimated. For examples: these four plots show mET spectra for various processes ATLAS Preliminary

Without SUSY signal With 1TeV SUSY signal

Top pair background for one lepton mode R:tt BG B:estimated Z and W background for no-lepton mode

Background could be estimated with real data itself with accuracy of about 50%

[4-4] Understanding of the background processes

R: W(→lν) B:estimated

SLIDE 31

tanβ=10, L=1fb-1

[4-5] Discovery Potential (including systematic errors)

tanβ=50, L=1fb-1

Stau LSP No EWSB

Results do not strongly depend on tanβ … One lepton & no lepton mode have the similar potential: up to 1.5TeV if m0 <1TeV

up to 1TeV (if squark heavy)

ATLAS Preliminary ATLAS Preliminary

˜ q ,˜ g ˜ g

Band shows the effect of systematic errors coming from background estimations

5σDiscovery 5σDiscovery

m(˜ g ) 2.5m1/2

m(˜ q ) m0 2 +6m1/2 2

SLIDE 32

We can discover SUSY with various event topologies: Not only Lepton, But also.. / E

T

multi leptons + High PT jets + b-jets τ-jets

These carry information about EW gaugino sector

SLIDE 33

Luminosity/expt (fb-1) 1 fb-1/expt M (TeV)

ATLAS + CMS

1 10 100 1 1.5 2.5 2

˜ q ,˜ g Up to 1.6TeV

(2TeV for 95%CL exclusion)

These do not strongly depend on model: Important parameters are masses of and the mass difference between them and LSP(>= 400GeV)

~1.6TeV g ~

˜

• 1

± 500GeV

˜

• 1

0 250GeV

Naïve GUT assumption Gaugino-like With L=1fb-1

˜ q ,˜ g

Let’s combine ATLAS & CMS

SLIDE 34

[4-6] Exclusive Study: mass can be measured:

˜ g

q

˜ q ˜

• 2

q

˜ l

R ±

˜

• 1

l l

Sharp Edge Mmax ll M ll max = m( ˜

• 2

0) 1 m(˜ l R ± ) m( ˜

• 2

0)

• 2

1 m( ˜

• 1

0) m(˜ l R ± )

• 2

Select interesting decay chain: Make kinematic distributions: Edge carries the information related to their masses:

Mlq max = (m(˜ q L)2 m( ˜

• 2

0)2)(m( ˜

• 2

0)2 m(˜ l R)2) m( ˜

• 2

0)2 Mllq max = (m(˜ q L)2 m( ˜

• 2

0)2)(m( ˜

• 2

0)2 m( ˜

• 1

0)2) m( ˜

• 2

0)2 Masses can be determined with an accuracy of about 1-10% (with help of model in general) model independent study on the coupling/mass is difficult @ LHC

SLIDE 35

[5] Large Extra Dimension

Plank Scale might be O(TeV) not 1019GeV

Gravity becomes very weak due to O(TeV) Extra Dimension

SLIDE 36

[5-1] Mini Black Hole

MPl=1TeV, n=2 MBH=6.3TeV

Ｍpl < 6TeV for n=2-7 (L=10fb-1)

d < Rs

Mini BH produce if partons collide within Rs cross-section huge (classical) (But there is large uncertainties near threshold)

BH evaporates with Hawking Radiation: Many energitic particles are emitted: MBH>MP

SLIDE 37

[5-2] KK graviton (gg->gK) will be observed in “monojet” topology

SLIDE 38

Most important/urgent topics in Particle Physics are: (1) Understanding of “the origin of mass” (EW symmetry breaking) SSB of Higgs field is most promising scenario, but should be examined directly: & determine the potential: (2) Beyond the Standard Model Supersymmetry is most promising, Large Extra Dimension, unexpected scenario… are also exciting. These are main purpose of LHC project: and LHC will give the clear solutions

[6] Introduction and Conclusion:

SLIDE 39

2008 !!

Appendix: Mt can be measured with accuracy of 0.9GeV, Mw will be 15MeV(Very difficult task. Z’ or high mass gauge boson 5TeV, Littele Higgs heavy top 1TeV

SLIDE 40

Backup

SLIDE 41

ＳＭ Higgsの研究で有効なチャンネルの纏め

Gluon Fusion

発見 (fake、高次効果研究） Mass測定 110-140GeV H -> γγ 発見・W coupling測定 130-200GeV H -> WW 発見・Mass, coupling測定 110-140GeV H -> ττ

Vector Boson Fusion

(鍵のチャンネル）

発見 130-170 GeV H -> WW 発見・Mass, spin, coupling測定 140-1000 H -> ZZ-> 4 l 発見 Mass 測定

spin=0の傍証

110-140GeV H -> γγ

有効な領域とその効能 崩壊過程 生成過程

SLIDE 42

SLIDE 43

Diphoton background is now computed at NLO (Binoth et al,

Eur.Phys.J.C16(2000)311, Bern,Dixon,Schmidt hep-ph/0206194, C.Balasz et al, Phys.Lett.B489(2000)157

SLIDE 44

1-6 ＭSSM Higgsの発見能力

軽いhはSM解析、 ほぼそのまま この緑の部分は、HＳＭに似た性質のhが観測されるだけ。（SUSY decay )

• tanβが大きいとbbH/Aの

結合が大きくなる。 H/A→ττ・μμ・(bb)

• tanβ>10で gb->tH-で

charged Higgs が観測可能 →MSSM Higgsも必ず L=30fb-1のrunで発見可能

ここら辺以外は１年でOK (t →H+b がcover)

SLIDE 45

H/A生成

tanβ gg→bbH/A→ττ、μμ、（bb）

10

← μのyukawa*tanβ 第２世代のYukawaを見るチャンス ← tanβ２で数が 増えるので見える

SLIDE 46

H/A生成

tanβ gg→bbH/A→ττ、μμ、bb

10

tanβを測定する重要なチャネル 軽いhがLEP見えない->大きなtanβ

SLIDE 47

Ｈ＋－

(t,b) Br=90% (τν) 10%

tan mt /mb

の時suppress

SLIDE 48

ＬＨＣでの主なSUSY生成過程は、 である。 生成断面積は、これらのmass以外にはモデル依存性が小さい。 ただのstrong interaction らは、 の崩壊過程で出てくる （多段cascade崩壊）LEP,Tevatronとの大きな違い

• Coloured partciles は重い
• はLSPで安定(R-parity) Cold DMの良い候補
• Higgsino mass (|μ|) > 0.8m1/2(Wino) (m0>>m1/2の場合以外)

→

• 第３世代の は軽い。(Yukawa+LR mixingの効果)

2-1 m SUGRAの簡単な纏め

５つのパラメター ： mo, m1/2, tanβ, A0, sign(μ) (mass @GUT) (VEV) (scalar 3点) (Higgsino mass) 一般的な傾向

˜

• 1

˜

• 1

0 ˜

B

0, ˜

• 2

0 ˜

W 0, ˜

• 1

± ˜

W ±, ˜

• 3,4

0 , ˜

• 2

± ˜

H

˜ f

( ˜ g , ˜ q ) ( ˜ g ˜ g , ˜ g ˜ q , ˜ q ˜ q )

˜

• 0, ˜
• ±, ˜

l

˜ g , ˜ q

SLIDE 49

˜ g ˜ q

L

˜ q

R

m(˜ g ) < m(˜ q ) m( ˜ g ) m(˜ q ) m(˜ g ) > m(˜ q ) ˜ g qq ˜ B

0( 1)

qq ˜ W 0( 2) qq ˜ W ±( 4) ˜ g t˜ t

1

b ˜ b

1

˜ g q˜ q

˜ q

L q ˜

W 0( 1) q ˜ W ±( 2) ˜ q

R q ˜

B ˜ q

L q˜

g ˜ q

R q˜

g

˜ g , ˜ q のdecay table

ここら辺はあまりモデルによらない。Massの関係やB,Wとχの関係、第３世代などがモデル依存

SLIDE 50

I II Decay to Higgs

m( ˜

• 2

0) m( ˜

• 1

0) > m(h)

˜

• 2

0 h ˜

• 1

˜

• 1

± W ± ˜

• 1

III IV

˜

• 1

±, ˜

• 2

0 の崩壊モードについて

2-Body decay chain

m( ˜

• 1

±),m( ˜

• 2

0) > m(˜

l

±)

˜

• 1

± ˜

l

± l± ˜

• 1

˜

• 2

0 ˜

l

±lm l±lm ˜

• 1

Decay to W/Z

m(h) > m > m(W,Z)

˜

• 2

0 Z 0 ˜

• 1

˜

• 1

± W ± ˜

• 1

3-Body decay

m < m(W,Z)

˜

• 2

0 ff ˜

• 1

˜

• 1

± ff ˜

• 1

tan >>1の時 が軽くなり、τへのdecay branchingが増える。 τ-IDが大切。Higgsino成分が多くなると、然り。

˜

• 1

これらは基本的にkinematics だけであり、依存性は少ない。 Sfermion propagatorで3body

SLIDE 51

4.TopとB-Physics

SLIDE 52

Topの質量測定

• 107 tt/10fb-1

非常に豊富な統計

• EWの重要なparameter

mt =1GeV sin2 eff = 3105 mW = 6MeV

2004年

SLIDE 53

Topの質量測定

• 107 tt/10fb-1

非常に豊富な統計

• EWの重要なparameter

mt =1GeV sin2 eff = 3105 mW = 6MeV

200９年

δMt=1GeV δＭW=15MeV Higgs発見

SLIDE 54

Semi-leptonic decay channel

• Br~2*0.7*0.2=0.28
• Jetの組み合わせの不定性小さい

mjj = MW

PDG,ml = MW PDG

mjjb = mlb = M top

fit

Kinematic fitを以下の条件でかけて Ｍtop

fitとχ2を求める。

χ2<4がちゃんと出来た条件 Ｍfit

top

• Comb. BG

SLIDE 55

χ2の悪いevent を調べてみると hard なFSR やνを出している。 結果としてEnergyが低くなっている。 χ２のbinごとにsliceしてそれぞれ

Mtopをfitする。十二分な統計がある のでそれぞれの点でも十分な統計精度

このままMtopをfitでだすと、 以前同様に FSRのsystematic error が大きい（1.3GeV） χ２→0がＭtop FSRの出方によらない。

0.9 !!!!

合計 0.1 組み合わせ 0.7 (まだ） b calibration不定(1%) 0.1 b fragmentation 0.5 FSR 0.1 ISR 0.2 q calibration不定 0.1 統計（10fb-1) Δｍ(GeV) Error Source

0.9GeV の精度

SLIDE 56

ATLAS preliminary

√s =900 GeV, L = 1029 cm-2 s-1

Jets pT > 15 GeV Jets pT > 50 GeV Jets pT > 70 GeV Υ→ µµ W → eν, µν Z → ee, µµ J/ψ→µµ

100 nb-1 30 nb-1

SLIDE 57

104 Tevatron-2 107 1.6 Hz tt

• 5×104

20個/時 SUSY(1TeV)

• 5×105

200個/時 Higgs(130GeV) 109 Belle 2×1012 (108 inc. di-μ) 200KHz (HLT 10Hz) bb: PT>10GeV 107 Tevatron-2 107 Tevatron-2 108 107 30Hz 3Hz W→eν Z→ee 他との比較 (2007年までの積算） 初めの１年で L=10fb-1 Event rate 2×1033 代表的な過程

僅かL=10fb-1でも膨大な統計量のデーターが観測

この表が示す様に、LHCは、Top-factory、 B-factoryであり、 同時に Higgs/SUSY factoryである。

( ECM=14TeVと高いので、SUSY以外にも、TC,EDなど 数TeVまでのnew physicsに対して高い生成レートを持っている。)

Calibration やControl sampleも十分出来る。 デザインＬの1/10の

SLIDE 58

Jetのcalibrationについて

• Beam testの結果で約5-10%の精度
• τ→ｈν E/p=1 (bias < 0.8% π０の混入）

E=20-250GeVの領域 320kevent/10fb-1

• tt→bbWWのW→jjを使う。一年で45k

E<200GeVまで。高いと1本に見える。

• Zj Zとjetのバランスでhigh Ptの領域

＝＞ 1%の精度が可能 これがネックにならない。 Ｗ，Ｚなどのサンプルも豊富にある ー＞ Calibrationに重要 Background control sample

SLIDE 59

EM calibration

• Δη×Δφ=0.2×0.4
• Beam test のデータで2%

非一様性 0.5%

• １ＨｚでZ→ee

250個/Sect. 数日で ＝＞ これで0.3% ＤＹ Z->ee １Hz

SLIDE 60

B-physics at ATLAS/LHCb

Bd J /(µ+µ)KS

0( + ) を用いたsin2βの測定

HLT:Pt>6GeV以上の2μ 約10Hzで収集

• K0

Sが再構成出来て、Bｄが再構成出来る。

S/B=32と非常に高い。

• 反対側のflavour tagは、semi-leptonic decayの

Leptonをtagする方法(εD2=0.7%)とleading πを 使う方法(εD2=2.4%)でtagする。

• 250k event/30fb-1 と統計も高い

Bd

（１） → Δsin2β=0.016 (stat.) +-0.005(sys.) 2%の精度でsin2βが測定可能 上には上が、、 LHCbは、B-physicsに特化した検出器： low Pt trigger, RICH:K,π,e,μ分離 119kevent/2fb-1 で、2%の測定を行う。

(約３年の測定）

SLIDE 61

Ａ gg→bb 500μｂの極めて大きな生成断面積 前方が多い： ＬＨＣｂ前方に特化して RICH K,π,μ分離 特殊な磁場で分離

SLIDE 62

• 30ps-1まで検出可能(LHCb 58ps-1）
• 0.05ps-1の精度で測定可能 Δms ~12ps-1

(2) Physics of Bs meson

Δms from Bs → Ds p and Bs→ Ds a1

Signal Bs->µµ Signal Bd->µµ BG ATLAS 92 14 660

(3) Rare decay Br~10-9