Belle II 実験における新物理探索

Belle II 実験における新物理探索
KEK ・素核研
伊藤　領介
Outline
1. Introduction
2.これまでに B ファクトリで見つかった新物理の兆候 ??
3. Belle II で探索する新物理の「 Golden Mode 」
4.さらに感度をあげるには？ = Global Fit
5. Belle II Japan としてどのように新物理探索に
取り組むか？
1. Introduction
そもそも「新物理探索」ってどういうこと？
- あまりこなれた言葉ではないけど、世界の高エネルギーの人
は理論実験を問わず New Physics がどうのこうのという議論を
している。これを直訳したもの。それを探索すること。
じゃあ New Physics って一体なに？
- 要するに Standard Model で説明できないような事象を全部
ごた混ぜにして New Physics と呼んでいる。
BSM (Beyond Standard Model) と言う人もいる。
- Standard Model で説明できない「確固とした」現象は今の
ところ LHC でも Belle でも他の flavor 実験でもみつかって
いない。
みつかっていないというけど、そういうのは一番エネルギーの高い
実験でしか探せないんじゃないの？
- そんなことはないのですよ、うさぎさん。トンネル効果を
ご存知か ?
- 不確定性原理を思い出しましょう。 DEDt > ћ/2 だから、
ものすごく短い時間であるならその瞬間だけは高い
エネルギーに達することができるのですよ。
(off-shell の反応という言い方をします。 )
- たとえば、 Btn という崩壊を考えます。これは B 中間子の
b と u クォークが結合して W ボソンを介して t と n に崩壊
します。でも b と u クォークの質量より W ボソンの方が
はるかに重い。普通に考えたらこんな崩壊は起きない。
- でも起きるんです。なぜか？トンネル効果があるから。
P.Urquijo
「直接探索」
「間接探索」
- 高エネルギーの歴史をひも解くと、間接探索における新物理の
兆候が、 Energy Frontier での新物理の発見に結びついている
例が多々ある。
* B-B mixing at ARGUS(1987) -> top quark at Tevatron(1995)
Coupling to NP
LHC
0.1
Tevatron
Comparison of NP sensitivity by
LHC and Belle II experiments
Belle
Belle II
0.01
0.001
1
100 TeV
10
Energy scale of NP
それぞれ良い点悪い点がある。
*High Energy Frontier では新物理の兆候を直接的に探索する
(Direct Search) 。
* 例） LHC Run I では Higgs の発見という大成果が得られた。
でも新しい物理に起因する事象は発見できていない。
=> 探索エネルギーに制限がある。
* Belle II をはじめとするフレーバーファクトリーでは High
Luminosity Frontier で稀崩壊を大量に収集し、その中の量子
トンネル効果の中の新物理の兆候を探索する (Indirect Search) 。
* しかし現在までのところ明らかな新物理の兆候は見つかって
いない。
=> 探索エネルギーの制限はないが、 low energy の事象を
扱うため、ハドロニゼーションの不定性のため新物理
の兆候が埋もれてしまうケースも多い。
ハドロニゼーション : クォークが「見える」素粒子に化ける過程
低いエネルギー領域でおこるので、通常の QCD で計算しにくい
2. 従来の B ファクトリでの新物理の兆候 ??
* ACP(B0K+p-)  ACP(B+K+p0) (5.6s discrepancy),
* Unexpectedly large D0-D0 mixing
(although SM pred. has large uncertainties)
* B->D*tn : ~5s discrepancy from SM
* Anomaly in “P5” in K*l+l- angular analysis at LHCb
• The direct CP violation “flips” between B⁰ and B⁺
772 x 10⁶ BBB
B⁰→K⁺π⁻
B⁰→K⁻π⁺
B⁰
ACP (K  π  )  0.069  0.014  0.007
ACP (K  π 0 )  0.043  0.024  0.007
Y.-T. Duh et al. (Belle Collab.),
Phys. Rev. D 87, 031103(R) (2013).
B⁺→K⁺π⁰
B⁻→K⁻π⁰
B⁺
B0K+pQuark level diagram is the
same for both decays.....
New physics ?
B+K+p0
Possible explanation of DACP(Kp) puzzle
P
T
+
Color
Suppressed
Tree
C
EW
Penguin
PEW
Expected to be negligible in SM
•　C.-W.Chaing, et al., PRD 70, 034020
• Enhancement of C ?
•　Y.-Y.Charng, et al., PRD 71, 014036
 C ＞ T is needed
•　W.-S.Hou, et al.,
PRL 95, 141601
•　S.Baek, et al.,
PRD 71, 057502
 breakdown of theoretical understanding
•　S.Baek, et al.,
PLB 653, 249
•　H.-n.Li,et al.,
PRD 72, 114005
• etc…
(C/T = 0.3–0.6 in SM)
• Enhancement of PEW ?
 Would indicate new physics.
• Due to poor understanding of strong int.?
Sum Rule : M. Gronau, PLB 627, 82 (2005); D. Atwood & A. Soni, Phys. Rev. D 58, 036005(1998)
Sum Rule tells ACP(K0p0) to be -0.15±0.05  Current W.A. +0.006±0.06
more statistics!
• Unexpectedly large D-D mixing
- Previously the mixing was observed in K, Bd and recently in Bs,
but not observed in D0
- Since the mass difference between d and s quarks is small, which
mainly contribute to the loop, GIM suppression effectively works.
-> The mixing is expected to be very small in the standard model.
Mixing Parameters
0
0
| D1 >= p| D >q | D > ,
(m1,G1)
m
x≡


y≡
2
0
0
| D 2 >= p| D >−q| D >
(m2,G2)
1
=

1 2 2
RM=  x  y 
2
SM prediction
yD ≡ ΔΓD/2ΓD (%)
xD  0.1%, yD  1%,
A. Petrov, Int. J. Mod. Phys. A 21, 5686
(2006)
Measurement Ave.
xD  (0.6300..19
20 )%
D⁰-DD⁰ 混合がないという
仮説は 10.2σ で棄却。
xD ≡ ΔMD/ΓD (%)
yD  (0.75  0.12)%
Average of
Belle,BaBar,CDF,CLEOc
L. M. Zhang et al. (Belle Collab.),
Phys. Rev. Lett. 96, 151801 (2006) etc.
- However, still SM predictions vary largely depending
on the model/calculartion .....
Standard Model predictions of D0-D0 mixing
- Prediction largely differs among models......
●
BD(*)tn
- Ratio of Br(BD(*)tn) to Br(DD(*)ln) (R) is
used to obtain the constraint.
 Vcb and a form factor uncertainties are canceled
BaBar
D*lν
Dlν
Dτν
D*τν
BaBar: PRL109,101802(2012), arXiv:1303.0571 (2013)
- Analysis with 471M BB events (full set)
- Improved hadronic tag
- BDT method for background elimination
R(D) = B(Dτν)/B(Dlν) = 0.440±0.058±0.042
R(D*) = B(D*τν)/B(D*lν) = 0.332±0.024±0.018
D*lν
Dlν
D*lν
Dlν
D*τν
Dτν
D*τν
Belle: PRL99(2007), PRD82(2010), hep-ex/0910.4301
- Naive average of inclusive and exclusive
hadronic tags (KEK-FF2013)
R(D) = B(Dτν)/B(Dlν) = 0.430±0.091
R(D*) = B(D*τν)/B(D*lν) = 0.405±0.047
D*lν
D*τν
●
BD(*)tn
- Ratio of Br(BD(*)tn) to Br(DD(*)ln) (R) is
used to obtain the constraint.
 Vcb and a form factor uncertainties are canceled
BaBar
D*lν
Dlν
Dτν
D*τν
BaBar: PRL109,101802(2012), arXiv:1303.0571 (2013)
- Analysis with 471M BB events (full set)
- Improved hadronic tag
- BDT method for background elimination
R(D) = B(Dτν)/B(Dlν) = 0.440±0.058±0.042
R(D*) = B(D*τν)/B(D*lν) = 0.332±0.024±0.018
D*lν
Dlν
D*lν
Dlν
D*τν
Dτν
D*τν
Belle: PRL99(2007), PRD82(2010), hep-ex/0910.4301
- Naive average of inclusive and exclusive
hadronic tags (KEK-FF2013)
R(D) = B(Dτν)/B(Dlν) = 0.430±0.091
R(D*) = B(D*τν)/B(D*lν) = 0.405±0.047
D*lν
D*τν
BaBar measurements have discrepancies from SM predictions.
2.0σ
2.7σ
SM expectations in S. Fajfer, J. Kamenik, I. Nisandzic, PRD 85, 094025 (2012).
Combined : 3.4s deviation
from SM.
Belle's have also....
R(D) = B(Dτν)/B(Dlν) = 0.430±0.091
R(D*) = B(D*τν)/B(D*lν) = 0.405±0.047
SM deviations:
R(D): 1.4σ
R(D*): 3.0σ
Combined: 3.3σ
LHCb
3. Search for New Physics at Belle II
- Examples of “Golden modes”
a) CPV in tree level and penguin decays
- sin 2f1(charm) vs. sin 2f1(strange)
b) CPV in radiative decays
- sin 2f1 in BKsp0g
c) Missing Energy
- pure leptonic decay of B : Bln (l=e,m,t)
- BD(*)tn
d) LFV
- tmg, tmmm
e) CPV in D0-D0 mixing
- Ultra-precise unitarity triangle measurement
1) CPV in bs transition
bB→cccs tree diagram
possible contribution of
new particle
bB→sqqc loop diagram
c~
Current measurement
sin2φ1sqqW.A  0.64  0.03
sin2φ1cc sW.A  0.682  0.019
* Deviation ~0.8s
SM predicts the same value
at a precision of ~1%.
Prospect in Belle II
d(sin2f1 (sqq))=
~0.012@50ab-1
* Some of systematics are cancelled by
taking the difference between measurements
for ccs and sqq.
21
2) CPV in B⁰→K⁰Sπ⁰γ (b→sγ)
bB→scγR: right handed photon
S
SM
b→sγL: left handed photon
 2ms
  sin 2φ1    
 mb



3) Missing Energy
a) Pure leptonic decay of B meson
(2HDM)
SM :
Br(Btn)SM = (1.11±0.28)10-4
HFAG13 Br(Btn)SM = (1.14±0.22)10-4
Prospect in Belle II
δ(Br) ~ 5% @ 50ab⁻¹
b) BD(*)tn
- World Average is shifted
~ 5s from SM prediction!
Constraint on Charged Higgs mass by Btn
Btn
Now (Belle+BaBar)
2HDM (Type II)
Excl. at
2σ
3σ
5σ
* 2HDM (Type II) cannot explain the difference between Dtn and D*tn in BaBar data.....
BaBar
* Detailed study with precise
measurements at Belle II is
required.
4) LFV : t>mg, t>mmm
Theoretically very clean test of standard model
SM:
NP:
Br ~ 10-25
Belle II sensitivity:
10-8~10-10 (90%CL)
5) CP Violation in D0-D0 mixing
Long distance
SM (+NP):
+
HFAG2013
Belle II 50ab-1
Physics Reach of Belle II and the LHCb upgrade
LHCb also....
4. Search for New Physics by Global Fit
NP search in such “gold plated” modes might be promising.
But is this method optimized for NP search?
Pros:
* Each mode gives a clean NP signal.
* Well-defined systematic uncertainties both in measurement
and theory prediction.
Cons:
* It is difficult to acquire high statistics in each individual mode
to conclude NP existence.
* The prediction of the single mode/measurement may depend
on a specific theory (esp. hadronization) which has a possibility
of some bias with a relatively large uncertainty.
-> This method may not be optimized for NP search.......
- A simple idea to improve the NP sensitivity is just to ask accelerator
physicists to increase the luminosity so that we can have more
statistics.
- But it is a difficult task. SuperKEKB, which is upgraded from
KEKB aiming at 40 times higher luminosity, is still a challenging
effort and the luminosity is not guaranteed...
- Question: How should we do to maximize the NP sensitivity
with a minimal accumulation of luminosity (data)?
One Idea
- If NP exists in quantum effect, it can affect on many
different measurements simultaneously.
- By combining multiple independent measurements sensitive
to the same NP, we can improve the sensitivity.
- But How?
- In order to combine multiple measurements,
* Describe the NP effects in various measurements using the
same parameter set in the theory and formulate the predictions
using the parameters.
* Calculate sum of c2 between each measurement and prediction,
and determine the parameter values by minimizing it.
* Study the shift in the parameter values from the standard model
predictions to search for NP.
- This technique is called as the global fit.
- By using the technique, we can gain
* An effective increase in event statistics usable for NP search,
* To relax the dependence on a specific (hadronization) theory.
- To perform the global fit, a consistent theory model with the same
parameterization to give predictions for measurements is the key.
Detail of global fit algorithm : Frequentist Approach
Experimental Likelihood
The likelihood components Lexp(i) : independent Gaussians
* Treatment of errors:
- Statistical error in measurement : Gaussian
- Experimental systematic error : Gaussian / Rfit
- Theoretical systematic error (<-Ltheo) : Gaussian / Rfit
* Normalization of likelihood components
- Likelihood ratio
- Equivalent to use “Dc2” -> Use CL interval calculation
Examples of Global Fit Analysis
1) Determination of Unitarity Triangle
- In the standard model, the quark mixing is described by
the Kobayashi-Maskawa matrix.
 
V ud V us V ub
d'
s ' = V cd V cs V cb
b'
V td V ts V tb

d
s
b

1− 2 / 2

 3 A−i  
2
2
−
1− /2
 A
=
3
2
 A1−−i  − A
1
*
*
*
V
V
V
V
V
V
- The unitarity condition td tb
cd cb
ud ub =1
is expressed in a trianlge.

Wolfenstein
Notation
- In the standard mode, the origin of CP violation comes
from the non-zero value of .
- Experimental determination of apex (,) was the goal of the
1st generation B-factory experiments (Belle and BaBar).
*
*
VudVub*
*
V td V tbV cd V cbV ud V ub=1
b  uln
with several
approaches
(excl. & incl.)
(, )
f2()
f3(g)
(0,0)
f1
VcdVcb*
B 
_
BB mixing (Dmd)
B DK
B D(*)p
VtdVtb*
f3
B0  p+p
B p
f2
f1()
(0,1)
B0  J/ KS(L), (2S) KS,
B  D(*)ln
cc1 KS, , c KS
Inputs to CKM fit
- Various measurements including outside B-factory results
are used for the fit.
a) B-factory measurements
* Angles :
sin(2f1) (+cos(2f1) for area constraint)
f2
f3
* Sides : absolute value of KM matrix elements
|Vub|, |Vcb|
* Bd Mixing
Dmd
* Leptonic/radiative decay
Br(B->tn)
exclusive
inclusive
bu
B  p ℓn
B  Xu ℓn
bc
B  D* ℓn
B  Xc ℓn
B-factory measurements for CKMfit
1) |Vcb| and |Vub|
dominant uncertainties
Form factor
OPE (|Vcb,ub|) and
shape function (|Vub|)
Vub
2
G(b  uln)
1


G(b  cln) Vcb 2 50
|Vub| ( 2 +2) is crucial for the SM
prediction of sin(2 )
|Vcb| ( A) is important in the kaon
system (K, BR(Kpnn ), …)
2) Dmd and Dms
This does not give a strong
constraint in , alone.
The point is:


s rel fB2d / s Bd / s =; 36%
→


s rel x 2  fB2s Bs / fB2d Bd =
; 10%
3) Angles of UT
f2
sin2f1
f3
Averaging measurements
- To use measurements of a quantity by different experiments in
the fit, the measurements have to be averaged.
- Many measurements are already averaged by HFAG group.
- However, the error treatment is not simple in some measurements
and a simple averaging cannot be used for them.
* ex. Measurements of CP angles f2 and f3 have multiple central
values with non-gaussian errors. The likelihood function is
provided by each experiment group for such a case.
-> A toy Monte Carlo simulation is performed and the average and
error are estimated based from the result.
b) Non B-factory measurements:
* K : Kaon CPV parameter from Kaon experiments
* Dms : Bs mixing parameter from Tevatron / LHCb
* |Vud|
* |Vus|
* MSbar quark mass
* s
........................
c) Theory parameters
- To obtain theory predictions, a variety of parameters in
hadronization theories have to be provided and included in the
global fit as input parameters.
Examples:
* fB, B (structure constant and Bag parameter) for Dm(d,s)
* Form factors to convert Br measurements into Vub, Vcb
* BK, ct, tt for K
etc.
- Most of them are obtained by Lattice QCD calculation, where
the errors is supposed to be non-gaussian.
-> Rfit treatment (CKMfitter).
- They still have relatively large errors, and they can directly
affect on the NP sensitivity in Belle II.
M.Pierini@CKM2006
梅 (ume)
竹 (take) 松 (matsu)
Results of global CKM fit (SuperKEKB prediction w/ 50/fb)
梅 (ume)
竹 (take)
松 (matsu)
梅 Ume
竹 Take
松 Matsu
s
s
5.1%
4.6%
3.1%
2.1%
2.0%
1.8%
Experimental
inputs to CKMfitter
(ICHEP2012)
Used Inputs: Theory parameters
2014 CKMfitter Result
(Moriond)
“Anomaly” in CKM fit
- Anomalous input value used for CKM fit is a possible signature
of NP.
- An anomaly in one measurement can be compared with
the value predicted by the CKM fit excluding that measurement.
- Example : “Tension” between B->tn and sin2f1
2010 Result
Br(Btn) = (1.68±0.31)x10-4 (CKMfitter ave. in 2010)
- 2.8s discrepancy at that time.
- First reported by global fit groups (CKMfitter, UTfit)
- Belle's new measurement in 2012 is significantly lower.
Br(Btn) = (1.68±0.31)x10-4 (CKMfitter ave in 2010)
Br(Btn) = (1.15±0.23)x10-4 (CKMfitter ave in 2012)
2012 result
The latest (ICHEP12) fit
with Belle's updated
Br(Btn) with hadronic tag.
“Tension” is relaxed.....
1.6s discrepancy
2014 Moriond
2) New Physics in B-B Mixing
CKMfitter: Phys.Rev.D83, 036004 (2011)
Model independent parameterization of New Physics in Mixing
q
SM
M 12
≡ M 12
⋅ q
SM


=

where
CP
phase
is
q
q
q

 q ≡∣ q∣exp i  q 
Principle:
NP parameters can be determined for by comparing
- measurements affected by NP parameters:
Dmd, Dms,Gd, Gs, ASL(t), asl, f1, f2
- measurements insensitive to NP
* tree level measurements : |Vub|, f3.......
For example:
parameterized
with NP
NP
insensitive
Constraint in NP parameters is obtained by the global CKM fit to all inputs.
2 scenarios in NP modeling
I) Non-MFV(minimal flavor violation)
Conventional model-independent NP parameterization
without assuming any flavor structure.
-> Ds and Dd can take different values.
II) With MFV (“generic” MFV with a large bottom Yukawa coupling)
Ds = Dd = D
Minimal Flavor Violation (MFV)
Assumption that all FCNCs stem from the KM-like matrix
element as in Standard Model.
Measurements sensitive to NP in mixing: Dm, DG/G, aSL
aSL/ASL
- ASL (Bd) : average of Belle/Babar/CLEO measurements.
- ASL(Bs) : D0
- aSL(Bs) : average of CDF/D0/LHCb measurements.
DGd/Gd : Belle/Babar, but exp. error is still large -> no constraint
DGs/Gs ,fs : CDF+D0+LHCb
Dmd : HFAG 2012
Dms : CDF + LHCb
f1, f2 : HFAG (Bd), fs:LHCb (Bs)
2012 CKMfitter results
non-MFV scenario
Bd
generic-MFV scenario
Bs
D = Dmd = Dms
non
MFV
gen.
MFV
Example 2 : Wilson Coefficients C7,C9,C10 の決定
Input Observables
New Physics Models
- CMSSM ( Constrained MSSM; 4 parameters )
- pMSSM ( phenomenological MSSM; 19 parameters )
Analysis by N.Mahmoudi et al
Example 3: 荷電 Higgs 粒子の探索
- B factory 実験では以下の反応を用いて荷電 Higgs 粒子
の探索を行っている。
Btn
BDtn + D(*)tn
- 比較する理論は Type II Two Higgs Doublet Model
* ２つのパラメータ
tan,
mH
a) Constraint on Charged Higgs from Btn only
Measurement:
Belle + BaBar average
Br(Btn) = (1.15 ± 0.23) x 10-4
prepared by
Y.Horii
2HDM Type II prediction:
Br(Btn)SM= (1.11 ± 0.28) x 10-4
obtained with:
- fB = (191±9) MeV (HPQCD, PRD86)
- |Vub| = (4.15±0.49)x10-3 (PDG,PRD86)
- Consistent with SM
- Stringent constraint on Charged Higgs.
* The constraint depends on fB and |Vub|
Excl. at
2σ
3σ
5σ
BaBar
b) BD tn
(*)
- Ratio of Br(BD tn) to Br(DD ln) (R) is
used to obtain the constraint.
(*)
(*)
D*lν
Dlν
Dτν
D*τν
<- Vcb and a form factor uncertainties are cancelled
BaBar: PRL109,101802, arXiv:1303.0571
- Analysis with 471M BB events (full set)
- Improved hadronic tag
- BDT method for event selection
R(D) = B(Dτν)/B(Dlν) = 0.440±0.058±0.042
R(D*) = B(D*τν)/B(D*lν) = 0.332±0.024±0.018
Belle: PRL99(2007), PRD82(2010)
- Naive average of inclusive and exclusive
hadronic tags (KEK-FF2013)
R(D) = B(Dτν)/B(Dlν) = 0.430±0.091
R(D*) = B(D*τν)/B(D*lν) = 0.405±0.047
D*lν
Dlν
D*lν
Dlν
D*τν
Dτν
D*τν
D*lν
D*τν
Br prediction by 2HDM consistent for both Dtn and D*tn
(Phys. Rev. D87, 034028 (2013) + private comm.)
b) Constraints in tan-mH plane by BDtn + D(*)tn combined
Belle
BaBar
tanβ
(incl. corr, tanβ/mH dep.)
(naive average (KEK-FF2013))
(w/o corr, w/o tanβ/mH dep.)
Excl. at
3σ
4σ
5σ
mH [GeV/c2]
2HDM Type II is rejected at more than
99.8% CL.
prepared by
Y.Horii
c) Constraint on Charged Higgs with all modes combined by global fit
Belle + BaBar : Btn + BDtn + BD*tn
* Correlation in D(*)tn measurements : BaBar - included in the fit, Belle - not considered.
* tanβ/mH dependence in D(*)tn measurements is omitted both for BaBar and Belle..
e
r
P
!
y
r
na
i
lim
prepared by
Y.Horii
Rejection
CL
2HDM Type II is rejected
at more than 99.99% CL in
the shown range
by Btn + BD(*)tn
- New Belle results of
BDtn and BD*tn
measurements will become
available soon.
 included in the fit update.
Mixing + Z->bb
Further constraints
1)
2)
b->sg
3)
1)
2)
3)
4)
4)
K->mn, t->Kn
D->mn
Ds->mn
Bd->tn
But 2HDM Type II is almost gone.... New NP model needed.
Further improvement of Global Fit approach
- If NP exists, its effect will be seen not only in B-factory
measurements, but also in various experiments.
- Global fit combining measurements at various flavor factories
(tau/charm factory + B factory + Kaon + LFV + EDM + g-2)
can drastically improve the NP sensitivity.
A.Buras (arXiv:1012.1447)
Belle II + J-PARC(Kaon,COMET, g-2/EDM) + LHCb.....
NP-Japan について
- 日本の理論家と実験屋が集まって（グローバルフィットを
用いて） Belle II の NP 探索感度を最大化する方法を考える。
- それに必要な作業を行う。
* NP 理論の選定とフレームワークの構築
( 種々の理論を effective theory に展開し parameter 化）
* その理論をグローバルフィットで実証するのに必要な
個々の解析モードのリストアップ
* Fitter engine の開発
- 2012 秋より活動開始。月 1 回の meeting ( とりあえず日本語）
現在のメンバー : 理論 ~15 人、実験 ~20 人
* D(*)tn – 理論 ( 田中、渡邊、坂木） + 実験（原 (K) 、佐藤、伊藤）
* NP と測定量の matching – 理論（後藤、長井、金児）＋
実験（樋口、住澤、西田、早坂 )
* SUSY modeling – 理論（後藤） + 実験（佐藤、早坂 .....)
* Fitter – 伊藤、佐藤
＋　野尻さん、橋本さん、堺井さん、林井さんなどの senior staff
による強力なサポート
SuperIso による SUSY constraint ( 名古屋大の佐藤さん）
- Nazilla Mahmoudi による C program 。種々の NP model
が組み込まれていて、そのパラメータを与えることにより、
種々の flavor 実験の測定量の予言値が求められる。
- これを用いて Belle (II) の測定に対する global fit でどこまで
NP model の制限が得られるかを study する。
佐藤
佐藤
佐藤
佐藤
B2TiP と NP-Japan
- B2TIP (Belle2 Theory Interface Platform) が始動した。
- B2TIP の中に New Physics working group があり、 B2TIP
の主要な活動となる。
- NP working group の goal は NP-Japan の活動と overlap
する部分が多い。
E.Kou
E.Kou
- B2TiP NP group workshop is scheduled on Feb.23-25 at Karlsruhe.
- 種々の New Physics Model のコードの使い方に関して Tutorial が
行われる予定。
- 関係者の皆様のご参加をお待ちしています。
NP-Japan の今後の活動方針
- D* tn 関連はそのまま進めていく。ただし理論モデル
は B2TiP のものと共通化する (SWAT はそのまま使用）。
-> 5/10/50 ab-1 での charged Higgs の探索範囲を
いくつかの model の下で出す。 ~1 年
-> B2TiP への feed back
- radiative decay を使った Wilson Coeff. C7,C9,C10 の
constraint もやるべきではないか？　( 伊藤は昔やった経験がある。）
- LFV をどうするか？
- 新たな topic はないか？
+
従来の NP model <-> new measurements の combination
の研究を進める。
Belle II MC activity について
- B2GM の Physics/Simulation session に出てみると、
日本からの参加者が非常に少ない！
- Physics/Simulation の activity はドイツに完全に遅れを
とっている。
- しかしまだまともな物理の simulation には到達していない。
reconstruction tool の開発が中心。
- 改めて simulation activity に参入するいいチャンスでは
ないのか？
NP-Japan 主導で「雑誌会＋データ解析講座」の開講を検討中
- Belle の初期の解析のペーパーをよみながら、そのを解析を
Belle II のモンテカルロデータでやってみることをと目標とする。
- Carriculum は
1) B+->J/(->l+ l-) K+ で、 reconstruction と PID の基礎から始めて、
2) B0->J/ KS(->pp,p0p0), J/yK* などで
Ks や p0 の reconstruction
3) B0->J/ KS の time dependent analysis から CPV 測定
- これを半年程度かけてゆっくりやっていこうと考えています。
- 講師になってくれそうな方々に個人的に声をかけていますが、
NP-Japan 内で近く議論の予定。
1 月開講を目指して準備を始めています。
予定している論文
K.Abe, et al., (Belle Collaboration),
“Observation of mixing-induced CP violation in the neutral B meson system”
Phys. Rev. D66, 032007 (2002).
MC 解析講座の方針
- basf2 based. Belle II の software library を使用。
- 基本的には kekcc ですべて解析を行うが、 local machine に Belle2 library
が install されていればそれを使用してもよい。
- GRID は使わない。すべて local 。必要な data file は kekcc 上に用意する。
必要に応じて各自 local machine に手で copy 。
- 実習はあらかじめ準備してある MC data をよんで reconstruction
を行うところから始める。
- MC data は最初は NP-Japan で準備する。のちに MC の走らせ方を別途
講義する。
- Belle2 analysis toolkit に含まれる Python の便利ツールの類は最初は使わない。
できるだけ C++ で直接 Belle II の MDST のオブジェクトを自分で触るスタイル
で進める予定。
Backup Slides
B0->K*l+l- angular distribution

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