Transcript CKM Quark Flavor Mixing Implications of the Most Recent Results B

CKM Quark Flavor Mixing
Implications of the Most Recent Results
on CP Violation and Rare Decay Searches
in the B and K Meson Systems
Andreas Höcker
LAL - Orsay
FPCP – Flavor Physics & CP Violation
Philadelphia, Pennsylvania, USA
May 16-18, 2002
Reference for recent plots: http://www.slac.stanford.edu/~laplace/ckmfitter.html
Determining the CP-Violating CKM Phase
CP Violation (CPV) in B and K Systems:
CPV in interference of decays with and without mixing
CPV in mixing

2

1

CPV in interference between decay amplitudes
Neutral Bd and Bs Mixing
Precise Determination of the
Matrix Elements |Vub| and |Vcb|
Detection of Rare Decays:
Search for new physics and direct CPV
Determination of weak phases
3
The CKM Matrix
Mass eigenstates  Flavor eigenstates  Quark mixing
B and K mesons decay weakly

modified couplings for
charged weak currents:
VCKM
Vud

 Vcd
V
 td
Vus
Vcs
Vts
Vub 

Vcb 
Vtb 
VCKM unitary and complex
4 real parameters
(3 angles and 1 phase)
Kobayashi, Maskawa 1973
Wolfenstein Parameterization (expansion in  ~ 0.2):
VCKM
 1  2 / 2

A 3    i  


2
2


1  / 2
A

 A 3 1    i   A 2

1


“Explicit” CPV in SM, if:
J  A2 6

J  Im VijVk Vi V
*
*
kj
0
CPV phase
(phase invariant!)
Jarlskog 1985
  0  no CPV in SM
Many Ways Lead to the Unitarity Triangle
Point of Knowledge:
SM or new
phases (fields)?
B  dγ
What is the value of
J/2
J
in our world?
η
 ρ, η 
Rb 

Rt

1, 0 ρ
0, 0
Tree
Loop
(mixing)
The CKM Matrix: Impact of non-B Physics
Observables
CKM
Parameters()
Experimental
Sources
Theoretical
Uncertainties
Quality
|Vud|
|Vus|

nuclear  decay
K+(0) +(0) e
small

K
  (1–)–1
K0  +–, 00
BK, cc

‘/K

K0  +–, 00
B6(QCD-peng), B8(EW-peng)
?
Im2[V*ts Vtd ...]
 (2A)4 2
K0L 0
small (but: (2A)4 )
  ()
|Vtd|
(1–)2 + 2
K+ +
charm loop (and: (2A)4)
 ()
()
Observables may also depend on  and A - not always explicitly noted
NA48
The CKM Matrix: Present Impact of B Physics
Observables
CKM
Parameters()
Experimental Sources
Theoretical
Uncertainties
Quality
md (|Vtd|)
(1–)2 + 2
BdBd  f +f – + X, XRECO
fBdBd

ms (|Vts|)
A
Bs  f + + X
 = fBsBs/fBdBd

sin2
, 
Bd  cc sd
small

sin2
, 
Bd  +(+) –
Strong phases,
penguins
?
B+  D0K+
small

b  u, Direct CPV
Strong phases,
penguins
?

, 
|Vcb|
A
b  cl (excl. / incl.)
FD*(1) / OPE

|Vub|
2 + 2
b  ul (excl. / incl.)
Model / OPE

|Vtd|
(1–)2 + 2
Bd   
Model (QCD FA)
?
|Vts|
A (NP)
Bd  Xs (K()) ,
K() l+l– (FCNC)
Model
?
|Vub|, fBd
2 + 2
B+  +
fBd

()
Observables may also depend on  and A - not always explicitly noted
Extracting the CKM Parameters
Constraints on
theoretical parameters
Measurement
xexp
Theoretical predictions
Xtheo(ymodel= ytheo , yQCD)
ytheo =(A,,,,mt…)
yQCD=(BK,fB,BBd, …)
“2” = –2 lnL(ymodel)
L(ymodel) = Lexp [ xxexp
exp
Assumed
to be
Gaussian
– xtheo(ymodel)]  Ltheo(yQCD)
« Guesstimates »
Frequentist: Rfit
Bayesian
Uniform likelihoods:
Ranges
Probabilities
Three Step CKM Analysis
fit package
Probing the SM
Test: “Goodness-of-fit”
Evaluate global minimum
²min;ymod(ymod-opt)
Fake perfect agreement:
xexp-opt = xtheo(ymod-opt)
generate xexp using Lexp
Perform many toy fits:
²min-toy(ymod-opt)  F(²min-toy)
Metrology
Test New Physics
Define:
ymod = {a; µ}
= {, , A,,yQCD,...}
Set Confidence Levels in
{a} space, irrespective of
the µ values
Fit with respect to {µ}
²min; µ (a) = minµ {²(a, µ) }
If CL(SM) good
Obtain limits on New
Physics parameters
If CL(SM) bad
²(a)=²min; µ(a)–²min;ymod
Hint for New Physics ?!

CL(SM) 
 F   2  d 2
2
 2   min;y
mod
CL(a) = Prob(²(a), Ndof)
AH, H. Lacker, S. Laplace, F. Le Diberder
EPJ C21 (2001) 225, [hep-ph/0104062]
Tree process
 no New Physics
Inputs Before FPCP’02 (status: Moriond 2002)
|Vud|
|Vus|
|Vcd|
|Vcs|
|Vub|
|Vub|
|Vub|
0.97394  0.00089
0.2200  0.0025
0.224  0.014
0.969  0.058
(4.08  0.61  0.47) 10–3
(4.08  0.56  0.40) 10–3
(3.25  0.29  0.55) 10–3
|Vcb|
(40.4  1.3  0.9) 10–3
(2.271  0.017) 10–3
(0.496  0.007) ps–1
Amplitude Spectrum’02
0.78  0.08
K
md
ms
Standard CKM fit in
hand of lattice QCD
sin2
mt(MS)
fBdBd

BK
(166  5) GeV/c2
(230  28  28) MeV
1.16  0.03  0.05
0.87  0.06  0.13
neutron & nuclear  decay
K   l
dimuon production: N (DIS)
W  XcX (OPAL)
LEP inclusive
CLEO inclusive & moments bs
CLEO exclusive
 product of likelihoods for |Vub|
Excl./Incl.+CLEO Moment Analysis
PDG 2000
BABAR,Belle,CDF,LEP,SLD (2002)
LEP, SLD, CDF (2002)
WA, Updates Moriond’02 BABAR
and Belle included
CDF, D0, PDG 2000
Lattice 2000
Lattice 2000
Lattice 2000
+ other parameters with less relevant errors…
B0B0 Mixing
–
Effective FCNC Processes
(CP conserving):
B0
––
[B=2]
b
d/s W
–
t
t
d/s
W
–0
B
b
whose oscillation frequencies md/s are computed by:
Perturbative QCD
CKM Matrix Elements
2
GF2
2
2

1
mq 
m
m

S
(
x
)
f
B
V
V

0.5
ps
B
W
B
t
Bq q
tq tb
6 2 q
mit : q  s, d
Lattice QCD (eff. 4 fermion operator)
Important theoretical uncertainties:

 rel fB2 Bd / s 
d /s
2
2
2
Improved error from ms measurement:  rel   fBs Bs / fBd Bd

36%
10%
Using ms
Experimental
error
> 5% CL
SM fit
> 5% CL
 Vtd
Theoretical
uncertainty
2
SM fit

Improvement
from ms limit
Waiting for a ms measurment at Tevatron...
Probing the Standard Model
Test of goodness-of-fit
Toy MC 2 distribution
2min
Confidence Level of Standard Model: CL(SM) = 57%
Metrology (I)
Standard Constraints
(not including sin2)
Region of > 5% CL
Metrology (I)
Standard Constraints
(not including sin2)
A TRIUMPH
FOR THE
STANDARD
MODEL AND
THE KM
PARADIGM !
KM mechanism
most probably
dominant
source of CPV
at EW scale
Metrology (I)
Standard Constraints
(including sin2)
sin2 already
provides one
of the most
precise and
robust
constraints
How to improve these constraints?
How to measure the missing
angles ?
...
Metrology (II): the sin(2) - sin(2 ) Plane
Standard Constraints
(not including sin2)
Be aware of
ambiguities !
Metrology (II): the sin(2 ) -  Plane
Standard Constraints
(not including sin2)
Metrology (III): Selected Numerical Results
CKM and UT Parameters
Rare Branching Fractions
Parameter
95% CL region
Observable
95% CL region

0.2221 ± 0.0041
BR(KL0)
(1.6 - 4.2) 1011
A
0.76 - 0.90
BR(K++)
(5.1 - 8.4) 1011

0.08 - 0.35
BR(B++)
(7.2 - 22.1) 105

0.28 - 0.45
BR(B++)
(2.9 - 8.7) 107
J
(2.2 - 3.5)  105
Theory Parameters()
sin(2)
– 0.81 - 0.43
sin(2)
0.64 - 0.84
Observable
95% CL region

77º - 117º
mt
(104 - 380) GeV/c 2

19.9º - 28.6º
fBdBd
(199 - 282) MeV

40º - 78º
BK
0.59 - 1.55
()
Without using a priori information
Constraint from Rare Kaon Decays: K+  +
Box:
Buchalla, Buras, Nucl.Phys. B548 (1999) 309
u
K+
u
c,t
s
W
+
d
l W
K+
s
c,t
|Vus |2

  V
l  e, ,
l
cs * Vcd X NL  Vts * Vtd X( xt )
top contribution


+
d
Z0

BR K       8 A4 X 2 ( xt )
u
W



Penguin:
u

BR K     
BR K    0e 
charm contribution
1
2
2
     0    


 
ellipse

Main theoretical uncertainty
comes from charm contribution

Experiment:
Two events observed at BNL (E787), yielding:

 

2
10
B K      1.57 1.75

10
0.82
E787 (BNL-68713)
hep-ex/0111091
Constraint from Rare Kaon Decays: K+  +
At present dominated by
experimental errors.
However:
uncertainties on |Vcb|4=8A4
will become important for
constraints in the - plane
Rare Charmless B Decays
We distinguish two Categories:
Semileptonic (FCNC) and radiative decays
(GF)2 increased compared to loop-induced nonradiative decays  (GF )2
Sensitive sondes for new physics
(SUSY, right-handed couplings, ...)
,
Box
,
W
b

tb
t Vtd ,s
V
u,c, t
Determination of HQET parameters
g,Z,
VtbVtd ,s
d
Hadronic b  u(d) decays
Tree
Measurement of CPV
Determination of UT angles  and 
b
Test der B decay dynamics (Factorization)
d
d,s
d
Penguin
b

W
d
Determination of |Vtd| and |Vts|
Search for direct CP asymmetry
,

u
u
d,s
d
W + Vud ,s
Vub
u
d,s
u
d
Radiative B Decays
The ratio of the rates B   to B  K* can be predicted more cleanly than
the individual rates: determines |Vtd|
2
Vtd
BR(B   )
2


1 RNP 

BR(B  K  ) Vts
Ali, Parkhomenko, EPJ C23 (2002) 89
see also :
Bosch, Buchalla, NP B621 (2002) 459
  0.76  0.06 , RNP  0.15
Source
B0   0
B    
(BR10–6)
(BR10–6)
Ali, Parkhomenko
0.5 ± 0.2
0.9 ± 0.4
Bosch, Buchalla
0.8 ± 0.3
1.5 ± 0.5
BABAR
< 1.5
< 2.8
Belle
< 1.0
< 1.1
CLEO
< 1.7
< 1.3
Rough estimate
of the theoretical
uncertainties !
Charmless B Decays
into two Pseudoscalars
[ Constraining  and  ?! ]
B  K and the Determination of 
Interfering contributions
of tree and penguin
amplitudes:
A Kπ  P  λ 2 e i γ T
Potential for significant direct CPV
CP averaged BRs and measurements of
direct CPV determine the angle 
SU(3) breaking
Rescattering (FSI)
EW penguins
The tool is: QCD Factorization...
... based on Color Transparancy
Large energy release
soft gluons do not interact with small qq-bar
color dipole of emitted mesons
non-fact. contributions are calculable in pQCD
perfect for mb .
Higher order corrections: (QCD/mb)
 see contributions at this
conference
Theoretical analysis deals with:
Fleischer, Mannel (98)
Gronau, Rosner, London (94, 98)
Neubert, Rosner (98)
Buras, Fleischer (98)
Beneke, Buchalla, Neubert, Sachrajda (01)
Keum, Li, Sanda (01)
Ciuchini et al. (01)
...list by far not exhaustive!
Soft scattering
Vertex corr., penguins
Hard scattering (pQCD)
M2
b
M1
d
Branching Fractions for B   /K
Updated Belle (La Thuile’02)
Updated BABAR (Moriond EW’02)
BR (106 )
CLEO
9 fb–1
BABAR
up to
56 fb–1
32 fb–1
World
average
Belle
B 0    
4.3 1.6
1.4  0.5
5.4  0.7  0.4
5.1  1.1  0.4
5.17  0.62
B 0  K  
17.2  2.5
2.4  1.2
17.8  1.1  0.8
21.8  1.8  1.5
18.6  1.1
B0  K K 
 1.9 (90%)
< 1.1 (90%)
< 0.5 (90%)
B     0
5.6  2.6
2.3  1.7
5.1  2.0  0.8
7.0  2.2  0.8
5.9  1.4
11.5  1.5
B   K  0
1.4
11.6 3.0
2.7 1.3
10.8  2.1  1.0
12.5  2.4  1.2
B   K 0 
18.2  4.6
4.0  1.6
18.2  3.3  2.0
18.8  3.0  1.5
B 0  K 0 0
 2.4
14.6 5.9
5.1  3.3
8.2  3.1  1.2
7.7  3.2  1.6
B 0   0 0
< 5.7 (90%)
< 3.4 (90%)
< 5.6 (90%)
18.5
2.3
2.2
8.9  2.3
Agreement among experiments. Most rare decay channels discovered
Direct CP Asymmetries in K Modes
BABAR:
BABAR
K 
CLEO
Belle
K 

ACP(K+–) = – 0.05  0.06  0.01
ACP(K+0) = +0.00  0.18  0.04
ACP(K0+) = – 0.21  0.18  0.03
Belle:
0
BELLE La Thuile’02
ACP(K+–) = – 0.06  0.08  0.08
ACP(K+0) = – 0.04  0.19  0.03
ACP(K0+) = +0.46  0.15  0.02
K S0 
CLEO:
1
BABAR Moriond’02
0.5
0
0.5
Are annihilation contributions important?
1
CLEO PRL 85 (2000) 525
ACP(K+–) = – 0.04  0.16
ACP(K+0) = – 0.29  0.23
ACP(K0+) = +0.18  0.24
World averages:
Agreement among experiments.
No significant deviation from zero.
ACP(K+–) = – 0.05  0.05
ACP(K+0) = – 0.09  0.12
ACP(K0+) = + 0.18  0.10
Bounds on 
Ratios of CP averaged branching fractions can lead to bounds on :
Fleischer, Mannel PRD D57 (1998) 2752
FM bound:
BF bound:
R
Rn 
 (B ) BR(K  )
<1?

 1.07 0.15
0.12
0
0 
 (B ) BR(K  )


1 BR(K  )
 1.04 0.37
0.22
0 0
2 BR(K  )

 no constraint
Buras, Fleischer EPJ C11 (1998) 93
1?
 no constraint
Neubert, Rosner PL B441 (1998) 403
NR bound:
1

R
BR(K  0 )
 0.24
2

1.24

0.21
BR(K 0  )
1?
 no constraint
See also recent Bayesian analysis: Bargiotti et al. hep-ph/0204029
Neubert-Rosner Bound
Tree
a)
T / P  3 / 2
2  BR(   0 )
 Rth (SU(3),BBNS)  (0.221 0.028)
0 
BR( K  )
f
 Rth  tanc K
f
Penguin
b)
QCD FA: small relative strong phases
a)
b)
CP Violation in B0  +– Decays
f
CP
q AfCP
p AfCP
 fCP
 e 2i 
CfCP 
AfCP (t )  CfCP cos(mdt )  SfCP sin(mdt )
SfCP 
1  | fCP |2
1  | fCP |2
2Im fCP
t 0
B0
~ e  2 i
B0
d

t
A f CP
CP
f CP
Af CP
1  | fCP |2
d
Tree diagram:
mixing
CP eigenvalue
ratio of amplitudes
Penguin diagram:

Vtd
Vub
For a single weak phase (tree):
q Af

 f e 2i (   )  f e2i
p Af
C = 0, S = sin(2)
For additional phases:
|  |  1  must fit for direct CP
Im ()  sin(2)  need to relate
asymmetry to 
C  0, S = sin(2eff)
sin(2eff) & Gronau-London Isopin Analysis
Using the BRs
: +–, ±0, 00 (limit)
and the CP asymmetries
: ACP(±0) , S , C
S – 0.01  0.38  1.21 0.41
0.30
and the amplitude relations: A / 2  A00  A0 ,
C – 0.02  0.30  0.94 0.32
0.27
 A  A
BABAR
BABAR
and A0  A0
Belle
sign convention changed!
Belle
2min=0.7
2min=2.8
BABAR: sin(2eff) & Theory (QCD FA)
S 
2Im 
1  
  e 2i 
Input: S & C
2
 i
, C 
1  
2
1  
2
e  P / T
e  i  P / T
& QCD FA (BBNS)
Input: S & C & sin(2WA)
Belle: sin(2eff) & Theory (QCD FA)
Zoom
Input: S & C
Input: S & C
The Reverse: sin(2eff , 2 ) & SM fit  THEORY
The theory provides tree und penguin contributions and their relative phases
The global fit determines the agreement between experiment and theory,
using all measured BRs and CP asymmetries (also time-dependent)
Determine also the free parameters of the theory (i.e., the CKM elements)
z  P / T / Rb
z  P / T / Rb
GR: Gronau, Rosner, Phys.Rev.D65:013004,2002
BBNS: Beneke et al., Nucl.Phys.B606:245-321,2001
BABAR / Belle
Where are we today
What brings the future ?
The Standard Model holds the castle:
We know the center
already quite well…
but it is too large!
A better understanding of long distance QCD opens the
shrine to a full exploitation of the
huge data samples
currently produced
at KEKB and PEPII.
...and the incredible
data quantities that
will be produced at
the Tevatron & LHC
And in the far future ?
In 2010 we will need
a zoom, to see the
overlap region...
And in the far future ?
Will there still be an
overlap region ?
v
And in the far future ?
... maybe we can establish new physics
before the LHC finds
it ???
?
Backup Material
Using ms
ms not yet measured. How to use the available experimental inform.?
Amplitude spectrum:
LEP/SLD/CDF
Following a presentation of F. Le Diberder
at the CERN CKM workshop (Feb. 02)
compute the expected PDF for the
current prefered value
compute the CL
infer an equivalent 2
Preferred value: 17.2 ps-1
Determination of the Matrix Elements |Vcb| and |Vub|
1/mQ
Symmetry of heavy quarks [=SU(2nQ)]:
in the limit mQ of a Qq system, the heavy quark
represents a static color source with fixed 4-momentum.
The light degrees of freedom become insensitive to spin
and flavor of the quark.
1/QCD
Compton wavelength
For both, |Vcb| and |Vub|, exist exclusive and inclusive semileptonic approaches.
The theoretical tools is Heavy Quark Effective Theory (HQET) and the
Operator Product Expansion (OPE)
|Vub| ( 2+2) is important for the SM prediction of sin(2)
|Vcb| ( A) is crucial for the interpretation of kaon decays (K, BR(K), …)
Exclusive Semileptonic BDl Decays
Measurement of B  D  rate as fct. of B   momentum transition 
Determination of |Vcb| from extrapolation to  1 (theory is most restrictive)
d(B  D  )
2
 F2 ( ) Vcb
d

HQ Symmetry:
F (1)  0.9 (  5%)
D
Belle

in B rest system
is  = (D)
F (1) Vcb
Bigi, Uraltsev;
Neubert;
...;
Lattice QCD

 =1
B
D  =1.5
35.6  1.7 (LEP)

 103  42.2  2.2 (CLEO)
36.2  2.3 (Belle)

Belle, PLB 526, 247 (2002)
Inclusive Semileptonic BXc l Decays
OPE: expansion of decay rate in QCD / mb und  s (mb )
Model-independent results for sufficiently inclusive observables:
Bigi, Shifman, Uraltsev; Hoang, Ligeti, Manohar
Experimental strategy
Vcb

BR(B  X c  ) 1.55 ps
0.0419
1 0.015pQCD  0.010mb  0.0121/ m3
b
0.105
B
Identify (4S )  B0B 0 by tagging one of the Bs:
Full reconstruction of the high energetic lepton
Select leptons from the semileptonic decay of the other B
0 /

+: „right-sign“

B

X
e

Fast
e
c
,
u
e

B0B 0 tag :  0 / 

–
B  X c ,uY , X c  X ' e  e Cascade e : „wrong-sign“
BR(B  X  )  Nfast / Ntag

BR(BX l(e)):
BABAR
BABAR: (10.82  0.21  0.38) %
Belle:
(10.86  0.14  0.47) %
CLEO:
(10.49  0.17  0.43) %
LEP:
(10.65  0.23
)%
ARGUS : ( 9.7  0.5  0.4 )%
BABAR preliminär:
z.B.: |Vcb|(BABAR)  (40.8 1.7 1.5)10–3
A promising approach for a theoretically improved
analysis is the combined fit of the HQET parameters
 und 1 (CLEO) by means of b  s. Allows to test
Quark-Hadron Duality. (See also spectral moments
analysis of hadronic Tau decays).
|Vcb|(CLEO)  (40.4 1.3)10–3
0.1
1
0
–0.1
–0.2
–0.3
–0.4
–0.5
CLEO, Phys. Rev. Lett. 87, 251808 (2001)
|Vub| from exclusive Decays (I)
Pure tree decay. The decay rate is
proportional to the CKM element |Vub|2

BR B  h
0
   Vub F (q )
 
2
2
B
+
Vub
b
2
d
Problem: form factor is model dependent
W
+
F  B   ,  , ,...

u
d
|Vub| from exclusive Decays (II)
CLEO
BABAR
B0    
other
bul
bcl und andere

  3.57  0.36

 0.60   10
0.21
CLEO : Vub  3.25  0.14 0.29
 0.55  10 3
BABAR : Vub
stat
CLEO, Phys.Rev.D61:052001,2000
BABAR preliminary (Moriond’02)
 0.33
 0.38
sys
mod
3
cross
feed
|Vub| from inclusive Decays
CLEO
Suppression of the dominant charm background by
cutting on the B Xul lepton momentum beyond the
kinematic limit of B Xcl
Problem: strong model dependence of |Vub|
B  Xs 
Reduction of model dependence by using HQE
and the “shape function“ measured in B  Xs 
CLEO, hep-ex/0202019
Vub   4.08  0.34  0.44  0.16  0.24   103
stat
fu
1/mb
HQE
Possible “violation“ of quark-hadron duality?
Measurement of the whole spectrum ( Theorie
under control) B Xul (Neural Net for Signal)
LEP B Working group


0.36  0.42  0.24
3
Vub  4.09 0.39

0.01

0.17

10
0.47 0.26
exp bc
bu
b
> 5% CL
HQE
Knowledge of b c background, incl. measurement ?
SM fit
BR(B   /K) & ACP & Theory (QCD FA)
Beneke, Buchalla, Neubert,
Sachrajda (BBNS)
Nucl.Phys.B606:245-321,2001
Theoretical
uncertainties:
ms, mc, B, RK
Renorm. scale 
Gegenbauer moms:
a1(K), a2(K), a2()
F(B), fB
XH, XA
This means:
error estimation not
settled yet !!!
Frequentist Approach: Rfit
the package
Three main analysis steps:
Probing the SM
Test: “Goodness-of-fit”
Evaluate global minimum
²min;ymod(ymod-opt)
Fake perfect agreement:
xexp-opt = xtheo(ymod-opt)
generate xexp using Lexp
Perform many toy fits:
²min-toy(ymod-opt)  F(²min-toy)
AH, H. Lacker, S. Laplace, F. Le Diberder
EPJ C21 (2001) 225, [hep-ph/0104062]
Metrology
Define:
ymod = {a; µ}
= {, , A,,yQCD,...}
Set Confidence Levels in
{a} space, irrespective of
the µ values
Fit with respect to {µ}
²min; µ (a) = minµ {²(a, µ) }
Test New Physics
If CL(SM) good
Obtain limits on New
Physics parameters
If CL(SM) bad
²(a)=²min; µ(a)–²min;ymod
Hint for New Physics ?!

CL(SM) 
 F   2  d 2
2
 2   min;y
mod
CL(a) = Prob(²(a), Ndof)
And in the far future ?
In maybe
Will
2010
there
wewe
still
will
be
need
an
...
can
esa zoom,new
overlap
region
to see
the
?
tablish
physics
overlapthe
v
region...
before
LHC finds
it ???
?