heavy flavour in a nutshell
DESCRIPTION
Heavy Flavour in a Nutshell. (for a 27-km annular nut at 1.8K) Robert W. Lambert, CERN. Flavour physics timeline. EXPERIMENT. AGS : CPV in Kaons. Gell-Mann: Strange . Chadwick: Neutron. Rutherford: Proton. SLAC: Up+Down. Argus: B-mixing. D + CDF: Top. E288: Bottom. SLAC: Charm. - PowerPoint PPT PresentationTRANSCRIPT
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Rob Lambert, CERN Moriond QCD, 22nd March 2011 1
Heavy Flavour in a Nutshell
(for a 27-km annular nut at 1.8K)
Robert W. Lambert, CERN
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Flavour physics timeline
Rob Lambert, CERN Moriond QCD, 22nd March 2011 2
THEORY
EXPERIMENT
Prout: Proton
Rutherford: Neutron
Cabbibo: angleBrout-Englert-Higgs-
Gell-Mann: 8-fold way
CKM: 3 rd Generation
GIM: charm
Ruth
erfo
rd: P
roto
nCh
adw
ick:
Neu
tron
Gell-
Man
n: S
tran
ge
SLAC
: Up+
Dow
n
SLAC
: Cha
rmE2
88: B
otto
m
D +
CDF
: Top
Guralnik-Hagen-Kibble
Anderson: EWSB
AGS
: CPV
in K
aons
Argu
s: B
-mix
ing
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Outline
1. Welcome to our universe
2. Introduction to flavour physics
3. Hottest new physics searches
4. Flavour-specific asymmetry
Recent papers: D measurement of Ab, 3.2s deviation from the SM (May 2010)
Evidence for an anomalous like-sign dimuon charge asymmetry PRL. 105, 081801 (2010)
Nierste and Lenz B-mixing update (Feb 2011)Numerical updates of lifetimes and mixing parameters of B mesonshep-ph arxiv:1102.4274
WMAP 7-year sky maps (Feb 2011)Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Sky Maps, Systematic Errors, and Basic Results Jarosik, N., et.al., 2011, ApJS, 192, 14
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Light
Rob Lambert, CERN Moriond QCD, 22nd March 2011 4(13.75 ± 0.13) Gyr
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Matter
Rob Lambert, CERN Moriond QCD, 22nd March 2011 5
73% Dark Energy
22% Cold Dark Matter
5% Atoms
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Antimatter
Rob Lambert, CERN Moriond QCD, 22nd March 2011 6
Matter + Antimatter = photons
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Antimatter
Rob Lambert, CERN Moriond QCD, 22nd March 2011 7
± CP-violation, CPVobservable difference between
matter and antimatter
Matter + Antimatter = photons
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Antimatter
Rob Lambert, CERN Moriond QCD, 22nd March 2011 8
10105.05.5 n
nbaryon
You Are Here
2010n
nbaryon
Where did you go?
Guys…? Guys…??
REALITY SM (maximal CPV)
± CP-violation, CPVobservable difference between
matter and antimatter
Matter + Antimatter = photons
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Rob Lambert, CERN Moriond QCD, 22nd March 2011 9
What does that have to do with heavy flavour physics?
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A beautiful image
Rob Lambert, CERN Moriond QCD, 22nd March 2011 10
m-
PV
SV
TV
Bs
Ds+
p+,K+,K
EVT: 49700980RUN: 70684
LHCb Preliminary
Heavy flavour is a microcosmof the entire standard model
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There are in general two types of new physics searches
Complementarity
Rob Lambert, CERN Moriond QCD, 22nd March 2011 11
Precision measurementsDirect Searches
“Old
phy
sics
” pr
evio
us c
ollid
er s
earc
hes
New Physics Scale / Collider Energy1 10000.1
Rare Decays
CP-violating asymmetries
Mixing parameters
CKM measurements
LSP
Higgs
Hidden valley
WIMP/
SMP
4th Gen
Rare Decays
CP-violating asymmetries
Mixing parameters
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Neutral mesons are
“mass-decay eigenstates are not the flavour eigenstates” Probably the weirdest phenomenon in physics!
“neither of those are the CP-eigenstates” CP-violation is very weird in itself Observation of CPV in Kaons in 1964, before any predictions!
Rob Lambert, CERN Moriond QCD, 22nd March 2011 12
0sB0
dB0K
0K
0K
(CPLear) (PDG) (PDG)
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Questions
1. Where is the CP-violation we need?
2. What is the flavour structure of new-physics?
But first we ask ourselves: How can we best look for this new physics, and where?
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Looking for NP
1. Find a place where new physics is unlikely
2. Precisely measure well-predicted observables
3. Find a place where new physics could enter
4. Precisely measure related observables
Rob Lambert, CERN Moriond QCD, 22nd March 2011 14
Unlikely: tree-level decays Likely: loops and penguins
0qB 0
qB?
q
q
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Looking for NP
1. Find a place where new physics is unlikely
2. Precisely measure well-predicted observables
3. Find a place where new physics could enter
4. Precisely measure related observables
Rob Lambert, CERN Moriond QCD, 22nd March 2011 15
Unlikely: tree-level decays Likely: loops and penguins
0qB 0
qB?
q
q
qq ?
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Looking for CPV SM has only one source of CPV, from the CKM, a phase
Observe this and any NP phase with interference: Need observables with two competing amplitudes
SM phase manifests most obviously in the b-quark system
Measure in many different ways to constrain the same phaseRob Lambert, CERN Moriond QCD, 22nd March 2011 16
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CKM - status Plot everything together on a single graph Everything is consistent ... so far ...
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Hottest new physics searches
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Looking for CP (1) Check CP-violating observables
Disagreement would point to CPV new physics
No hints yet, but the angle is not well known
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Looking for flavour (1) Bd K*mm has both loops and penguins!
Amongst many observables Afb is sensitive to SUSY
Rob Lambert, CERN Moriond QCD, 22nd March 2011 20
e.g.
CDF
SM
BELLE
BABAR
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Looking for flavour (2) Very rare decays, where SM BR predictions are very good
In the case of Bs/dmm, the rate is very sensitive to SUSY
Rob Lambert, CERN Moriond QCD, 22nd March 2011 21
CDF Prelim:
e.g.
LHCb:
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Looking for CP (2) CP-asymmetry in decays (Direct CP-violation)
Interesting hint: the BKp “puzzle”
Precision two-body B-decays will be very interesting
Rob Lambert, CERN Moriond QCD, 22nd March 2011 22
ACP
CP asymmetry
HFAGAugust 2010
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Mixing can be modified in both magnitude and phase
Define a complex number parameter Dq for the new physics
Just like we did with the CKM Collect all the measurements together Plot all at once in 2D (complex plane)
Looking for both
Rob Lambert, CERN Moriond QCD, 22nd March 2011
0qB 0
qB?
23
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SM is disfavoured by 3.6s
Owing a lot to the recent D measurement
Status: NP in mixing?
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Flavour-specific asymmetry… a smoking gun for new physics??
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Surprise!
Rob Lambert, CERN Moriond QCD, 22nd March 2011 26
…
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Translate Very difficult measurement
Observe
Flavour-specific asymmetry from B0-mixing in the SM:
In the standard model afs is almost negligible
Rob Lambert, CERN Moriond QCD, 22nd March 2011 27
)( ++mmN ≠ )( mmN
4103.00.2 SM2
dfs
sfsb aa
A+
%3.01D
b b
c
m
nc
bm
n
CP asymmetry in mixing, afs
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Hot Topic
Rob Lambert, CERN Moriond QCD, 22nd March 2011 28
Situation couldreally be clearedup by LHCb
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Current status LHCb is reconstructing both and
LHCb is catching up with D very quickly
Rob Lambert, CERN Moriond QCD, 22nd March 2011 29
~100k Ds in 5 fb-1 ~100k Ds in 0.2 fb-1
mnm ss DB0
mnm dd DB0
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Experimental Challenge LHC is a pp-collider, not a pp-collider
LHCb is in the forward region Can’t measure the same thing as D Need a clever new method
Subtract two asymmetries to eliminate systematics
Rob Lambert, CERN Moriond QCD, 22nd March 2011 30
4103.01.22
Ddfs
sfs
fs
aaA
+ 4103.00.2~2
~dfs
sfsb aa
ANB: D(inclusive)
LHCb(subtraction)
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After 1fb-1 of LHCb
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LHCb measurement cuts at right-angles to D
Only one exampleof the great physicson the way from LHCb
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Summary
? Need new physics to explain the observed universe LHC is a discovery machine Precision measurements complement direct searches
LHCb is the flavour experiment at the LHC BKp, CKM-angle , Bs/dmm, BdK*mm, BsJ/yF ...
? We’ve seen a hint of new physics already from D LHCb will make an early complementary measurement
This is only the start of the LHC era, so .... Stay tuned for the latest experimental results!
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End Backups are often required
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Acknowledgements Ulrich Kerzel for discussions on two-body B-decays
Guy Wilkinson and Thomas Ruf for their great advice
Johannes Albrecht for discussions on Bsmm
The CKM-fitter members of LHCb for updating the bs plot, pointing out to me a long-standing physics goof in our TDR and other publications, and for putting up with my crazy questions about their fitting methods
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Further References LHCb:
Bsmm first result: http://arxiv.org/abs/1103.2465 Detector paper: J. of Instrumentation (No. 3 pp. S08005P) “Roadmap” of physics analyses: arXiv:0912.4179
– Chapter 2: – Chapter 3: B Kp– Chapter 5: Bs/d mm– Chapter 6: K* mm
DAfs studies: – R.W. Lambert, CERN-THESIS-2009-001– N. Brook et al., CERN-LHCb-2007-054
CPLear: Kaon mixing: Physics Reports, Volume 374, Issue 3, Pages 165-270 (January 2003)
Experimental averages: CKM fitter group : http://ckmfitter.in2p3.fr/ HFAG (B Kp): http://www.slac.stanford.edu/xorg/hfag/rare/ichep10/acp/index.html
More on BKp Theory Status: S. Mishima from CKM 2010, arXiv:1101.1501 New Physics : S. Baek et al., arXiv:hep-ph/0412086
CDF Bs/d mm : CDF Public Note 9892 (preliminary)
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Further introduction
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Gravity
Rob Lambert, CERN Moriond QCD, 22nd March 2011 37(13.75 ± 0.13) Gyr
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Antimatter
Rob Lambert, CERN Moriond QCD, 22nd March 2011 38
10105.05.5 n
nbaryon 2010n
nbaryon
REALITY SM (maximal CPV)
± CP-violation, CPVobservable difference between
matter and antimatter
Matter + Antimatter = photons
Mass of entire solar system: 2x1030 kg Mass of largest asteroid, Ceres: 1021 kg
Area ~ Kazakhstan: Population~one small dog
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CKM and CPV CPV in the SM is ensconced in a single unitary matrix
The phase is most readily observed in the b-quark system
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The CKM matrix
Three real parameters
One complex phase violates CP
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Unitarity Triangles Product of rows and columns are constrained by unitarity
Of the nine relationships, six form a unitarity triangle
The most well-known triangle is:
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CKM - status Couplings, rates and mixings constrain magnitudes Asymmetries and mixings constrain phases
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Mixing observables
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QM 101 The most basic hamiltonian of anything
Because:
Rob Lambert, CERN Moriond QCD, 22nd March 2011 43
XiMXdtdiH XX
2
tiMiHt eetX ~~
Wave-like propagation Decay
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Mixing It’s weird, it’s confusing… it must be quantum mechanics
In the b-system, for example, we have two coupled states
Simplest one-line hamiltonian is now a matrix
Off-diagonal elements provide mixing and interference
Rob Lambert, CERN Moriond QCD, 22nd March 2011 44
0qB 0
qB?
q
q
)(
)(2)(
)(0
0
0
0
tB
tBiMtB
tBdtdi
q
qqq
q
q
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Mass-decay So, it’s not a diagonal matrix… OK
let’s diagonalize it to find:
Not the flavour states, a time-dependent mixture of them!
Rob Lambert, CERN Moriond QCD, 22nd March 2011 45
tiMiHtH
HHeetB ~~
tiMiHtL
LLeetB ~~These are the mass-decay-eigenstates
0sB0
dB
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Observables Four simple observables:
1. Average width
2. Average mass
3. Width Difference
4. Mass Difference
And we also have a phase, which violates CP:
All very predictable observables in the SM
Rob Lambert, CERN Moriond QCD, 22nd March 2011 46
D q
qqq
LqHq M12
1212 arg2
2211, +
qqL
qHq MMMm 122D
2211, MMM +
q
qqfs M
a12
12Imand/or
q
q
qM
12
12arg
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Flavour-specific asymmetry… a smoking gun for new physics??
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Translate
1. pp-interactions within a symmetric experiment
2. Correct all experimental biases (magnets, mis-id …)
3. Observe
4. In the SM, the favoured way to make charge asymmetry is if:
5. Which comes from B0-mixing:
In the standard model it is almost negligible
Rob Lambert, CERN Moriond QCD, 22nd March 2011 48
)( ++mmN ≠ )( mmN
++ mmbb ≠ mmbb
XBBBBbb ++ mm0000 ~ ≠ XBBBBbb mm0000 ~
4103.00.2 SM2
dfs
sfsb aa
A+
%3.01D
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Discovery Potential afs is very sensitive to new physics (NP) even if:
Tree-level processes are SM-dominated SM flavour structure Unitary CKM
With very weird scenarios (like leptoquarks) Probe NP mixing, interference and/or decays
Usual formula is modified:
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SM
SMSM
Ma
12
12Im
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Discovery Potential afs is very sensitive to new physics (NP) even if:
Tree-level processes are SM-dominated SM flavour structure Unitary CKM
With very weird scenarios (like leptoquarks) Probe NP mixing, interference and/or decays
If we allow a single NP phase in the mixing
Rob Lambert, CERN Moriond QCD, 22nd March 2011 50
sinRecosIm12
12
12
12SM
SM
SM
SMNP
MMa
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Discovery Potential afs is very sensitive to new physics (NP) even if:
Tree-level processes are SM-dominated SM flavour structure Unitary CKM
With very weird scenarios (like leptoquarks) Probe NP mixing, interference and/or decays
If we allow a single NP phase in the mixing (first part is just the SM value)
Rob Lambert, CERN Moriond QCD, 22nd March 2011 51
sinRecosIm12
12
12
12SM
SM
SM
SMNP
MMa SM
fsa
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Discovery Potential afs is very sensitive to new physics (NP) even if:
Tree-level processes are SM-dominated SM flavour structure Unitary CKM
With very weird scenarios (like leptoquarks) Probe NP mixing, interference and/or decays
If we allow a single NP phase in the mixing (first part is just the SM value)
Up to 200-times the SM!!! [[[ ... still... < D measurement ]]]Rob Lambert, CERN Moriond QCD, 22nd March 2011 52
+
sinRecosIm12
12
12
12SM
SM
SM
SMNP
MMa 5101.2 3100.4
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Flavour-specific asymmetryAt LHCb
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Experimental Challenge At the LHC we have extra complications in the measurement
Polluting asymmetries, which are all much larger than afs
Production asymmetry dp ~(10-2) Detector asymmetry dc ~(10-2) Background asymmetry db ~(10-3)
Use a, time-dependent, untagged, simultaneous fit to Bs+Bd
Subtract two asymmetries to eliminate detector component
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4103.01.22
Ddfs
sfs
fs
aaA
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Experimental Challenge At the LHC we have extra complications in the measurement
Polluting asymmetries, which are all much larger than afs
Production asymmetry dp ~(10-2) Detector asymmetry dc ~(10-2) Background asymmetry db ~(10-3)
Use a, time-dependent, untagged, simultaneous fit to Bs+Bd
Subtract two asymmetries to eliminate detector component
Rob Lambert, CERN Moriond QCD, 22nd March 2011 55
4103.01.22
Ddfs
sfs
fs
aaA
+ 4103.00.2~2
~dfs
sfsb aa
ANB: D
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Rob Lambert, CERN Moriond QCD, 22nd March 2011 56
The simple formula
qqb
q
qqp
qfs
qc
qfsq
fs SB
ttmaa
tA
+
DD
+
22/coshcos
2222)( ddd
10-3 -> 10 -5
ff
fftAqfs +
)(
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Rob Lambert, CERN Moriond QCD, 22nd March 2011 57
The simple formula
Polluting asymmetries are much larger than afs
Detector asymmetry dc ~(10-2) Production asymmetry dp ~(10-2) Background asymmetry db ~(10-3)
qqb
q
qqp
qfs
qc
qfsq
fs SB
ttmaa
tA
+
DD
+
22/coshcos
2222)( ddd
1//
1)()(
1)()(
0
0
SBSB
ININ
ff
b
p
i
ic
d
d
d
10 -2 10 -2 10 -310-3 -> 10 -5
Very Complicated
ff
fftAqfs +
)(
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Simplify We measure time-dependent decay rates:
Ac, Ap and Afs are correlated and cannot be separately fitted
First, reparameterise
Rob Lambert, CERN Moriond QCD, 22nd March 2011 58
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Reparameterise Just to make it easier to see what we’re doing…
production asymmetry is an initial state asymmetry
Changes the mixing amplitude, does not change the physics
Fit for x1 independently, which now only has detector asym
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The subtraction method Take Bs/Bd with the same final states ( =KKp m)
All production asymmetry is in x2/x3, just throw it away
Measure the difference between Bs and Bd
Rob Lambert, CERN Moriond QCD, 22nd March 2011 60
f
2211,
dfs
sfs
dsds
fs
aaxxA
D 45.06.0 105.2 +
+SM
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Projections MC sensitivities, Real data yields and systematics
0.1 fb-1 s~5x10-3 ... First result (2011) 1.0 fb-1 s~2x10-3 ... 5s observation? (2012/2013)
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LHCb projections
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J/y F
Rob Lambert, CERN Moriond QCD, 22nd March 2011 63
LHCb MC!
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K*mm
Rob Lambert, CERN Moriond QCD, 22nd March 2011 64
BaBar 657M bb-pairs
LHCb MC 1fb-1
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mm
LHCb will exclude most SUSY models this year!
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Misc
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Looking for flavour (3) Check loop-level observables
Would need a very accurate determination of dmd/dms
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c.f. J/Y F
Rob Lambert, CERN Moriond QCD, 22nd March 2011 68
Directly Measure sin s
s(s) = 0.05c in 1 fb-1
Effectively Measures
s() = 0.5c in 1 fb-1
But they constrain NP differently Effective power enhanced NB physical limit of afs is at 4x10-3 < current D result!
F y/0 JBs
sfsa
sinRecosIm
12
12
12
12
MM