Theory Summary
Patricia Ball
IPPP, Durham
1st LHCb Upgrade Workshop, Jan 12 2007
Flavour in the era of the LHC
1st LHCb Upgrade Workshop
Edinburgh, Jan 11-12 2007
Michelangelo L. Mangano
Theoretical Physics Unit
Physics Department
CERN, Geneva
Patricia Ball
– p.1/28
What is Òßavour physicsÓ ?
¥ In the SM, ßavour is what deals with the fermion sector
(family replicas, spectra and mixings):
¥
¥
all ßavour phenomena are encoded in the fermion Yukawa
matrices.
Beyond the SM, ÒßavourÓ phenomena cover a wider
landscape. E.g.
¥
¥
¥
Flavour changing processes, both with !Q=1 and !Q=0, can be
mediated by
¥
gauge-sector particles, like charged higgses, gauginos, new gauge
bosons, or by
¥
SUSY scalar partners
New sources of CP violation (phases in gluino, Higgs, etc. couplings)
New ßavours may exist in the form of new generations, exotic
partners of standard quarks (e.g. Kaluza Klein excitations, mirror
3
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– p.2/28
EWSB and ßavour
¥ EWSB is intimately related to ßavour:
¥
¥
¥
¥
No EWSB
fermions degenerate
Why mtop = g/!2 mW (
no visible ßavour effect
ytop = 1) ?
In most EWSB models ßavour plays a key role. E.g.:
¥
¥
¥
Technicolor: killed by too large FCNC?
¥
Little Higgs theories
Supersymmetry: large value of top mass drives radiative EWSB
In several extra-dim models the structure of extra dimensions -driven by the need to explain the hierarchy problem of EWSB -determines the fermionic mass spectrum
top quark partners, mirror fermions, ...
The large top mass is responsible for the Òsmall hierarchyÓ
problem .....
4
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– p.3/28
Where does Flavour Violation come from?
Origin in SM: Yukawa interactions:
LSM
=
LG (ψ, W, φ)
|
{z
}
+
kinetic
energy +
gauge IA
Higgs potential
→ spontaneous
symmetry
breaking
|
{z
|
{z
}
gauge sector
LH (φ)
| {z }
+
LY (ψ, φ)
| {z }
Yukawa IA
→ fermion
masses
}
scalar sector
And flavour violation beyond the SM?
Parametrize by effective operators in effective field theory!
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New Physics in Heavy Flavours
LHCb Upgrade Workshop
Edinburgh – January 11, 2007
Yossi Nir (Weizmann Institute of Science)
Patricia Ball
– p.5/28
Theory Motivation at the LHC Era
The NP CP/Flavor Problem
1
2
• m2H ∼ (m2H )tree + 16π
2 ΛNP
To avoid fine-tuning of the Higgs mass,
ΛNP <
∼ 4πmW ∼ 1 T eV .
¯ d¯
• LNP ∼ Λ21 sds
NP
To avoid too large contributions to εK and to ∆mK,D,B ,
3−4
ΛNP >
10
T eV .
∼
New Physics at the TeV scale must have a
very non-generic flavor and CP structure
Patricia Ball
– p.6/28
Theory Motivation at the LHC Era
The NP CP/Flavor Problem
1
2
• m2H ∼ (m2H )tree + 16π
2 ΛNP
To avoid fine-tuning of the Higgs mass,
ΛNP <
∼ 4πmW ∼ 1 T eV .
¯ d¯
• LNP ∼ Λ21 sds
NP
To avoid too large contributions to εK and to ∆mK,D,B ,
3−4
ΛNP >
10
T eV .
∼
This
also whatatMFV
about
– butmust
with ahave
restricted
NewisPhysics
the isTeV
scale
a
set of operators and size of couplings.
very non-generic flavor and CP structure
Patricia Ball
– p.7/28
Closed Questions
Conclusions (I)
Current Status of CKM Picture
• The KM phase is different from zero (SM violates CP)
• The KM mechanism is the dominant source of the CP violation
observed in meson decays
0
• The size and the phase of NP contributions to B 0 − B mixing
and to Bs − B s mixing are severely constrained
• Complete alternatives to the KM mechanism are excluded
(Superweak, Approximate CP)
• No evidence for corrections to CKM
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– p.8/28
Hints in present data
Is there NP in b → s transitions?
Theory motivation: SUSY as an example
• U(1) models
Naive estimate: δsR bR ∼ (ms /mb )/Vcb ∼ 1
The only FC coupling expected to be of order one
• GUT models
δsR bR related to Uµ3 = O(1)
RGE effects enhance δsR bR
Experimental motivation: ∆Sf ≡ −ηf Sf − SψKS
• ∆Sf (b → s) = O(0.1) not excluded
A hint for ∆Sf (b → s) = O(0.1)?
Patricia Ball
– p.9/28
Exclusive b → s Transitions at the LHC
Patricia Ball
IPPP, Durham
1st LHCb Upgrade Workshop, Jan 11 2007
Patricia Ball
– p.10/28
Observables
B → K ∗γ
branching ratio
isospin asymmetry
CP asymmetry
B → K ∗ `+ `−
branching ratio
forward-backward asymmetry
helicity/transversity amplitudes (partially integrated over invariant
lepton mass)
Bs → ` + ` −
branching ratio
Patricia Ball
– p.11/28
B → K ∗ `+ `−
Patricia Ball
– p.12/28
Spin Amplitudes
B 0 → K ∗0 (→ K − π + )`+ `− : differential distribution:
d4 Γ ∝ I(s, θl , θK ∗ , φ)dsd cos θl d cos θK ∗ dφ depends on 4 spin amplitudes:
A⊥ , A k , A 0 , A t
Patricia Ball
O – p.13/28
Spin Amplitudes
Can construct various observables: e.g. forward-backward asymmetry AF B
and
−2Re(Ak A∗⊥ ) (2)
|A2⊥ | − |Ak |2
(1)
transverse asymmetries: AT (s) =
, AT (s) = 2
.
2
2
2
|Ak | + |A⊥ |
|Ak | + |A⊥ |
Patricia Ball
O – p.13/28
Spin Amplitudes
To what accuracy can these amplitudes be measured at LHCb/upgrade?
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– p.13/28
Theory Framework (Beneke/Feldmann/Seidel 01/04)
similar to B → K ∗ γ : QCD
factorisation, include
non-factorisable radiative
corrections
only valid to leading order in 1/mb
and for small q 2 : otherwise, QCD
factorisation breaks down
charm resonances cause
amplitude to diverge for
q 2 → 4m2c ; restrict calculations to
q 2 < 3m2c ≈ 6 GeV2
position of zero of AF B shifted
upon LO → NLO
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! "
5
FB Asymmetry in B → K ∗``
resonances
4
0.4
purely SD
contrib.
3
MIA (C 7>0, C10>0)
0.2
MIA (C 7<0, C10>0)
SUGRA
SUGRA (C 7 <0)
MIA (C 7<0)
-0.2
1
SM+FF uncertainties
15
20
0
2
4
6
10
8
#
&
'
%$
5
SUGRA, MIA (C 7>0)
-0.4
0
0
SM
*)(
2
0
MIA
part of hadronic uncertainties cancels in FB asymmetry
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– p.15/28
Specific NP Example
Spin-Flipped Currents in SUSY (Lunghi/Matias 06)
NP via new operator O70 ∝ s̄σµν PL bF µν (SM has O7 ∝ s̄σµν PR bF µν )
NP ↔ gluino-squark loops
(1,2)
integrated transverse asymmetries AT not very sensitive to hadronic
form factors and NLO QCD factorisation corrections
4.5
1
4.25
Patricia Ball
4
0.5
3.75
0.25
AT 1,2
BR HB -> Xs ΓL ´ 104
0.75
AT 1
3.5
3.25
0
-0.25
3
-0.5
2.75
-0.75
-0.4 -0.2 0 0.2 0.4
Ceff7' HΜb L
AT 2
NLO
-0.2 -0.1 0 0.1
Ceff7' HΜb L
0.2
– p.16/28
Summary & Prospects
exclusive b → sγ, µ+ µ− very versatile NP discovery/constraints channel
for LHCb
good (theory-robust) observables:
isospin and CP asymmetry in B → K ∗ γ
foward-backward asymmetry in B → K ∗ `+ `−
transversity asymmetries
homework for theorists:
form factors (this appears to be a time-invariant statement. . . )
include effect of charm loops
question to experimentalists:
measurement of spin/helicity amplitudes in B → K ∗ `+ `− ?
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– p.17/28
Introduction
Target Simulation
Cost of the Simulations
B-Physics
Conclusions
Prospects for Lattice Phenomenology
Chris Sachrajda
School of Physics and Astronomy
University of Southampton
Southampton
UK
1st LHCb Collaboration Upgrade Workshop
Edinburgh, January 11 – 12 2007
Lattice Phenomenology
Patricia Ball
LHCb Upgrade Workshop, Edinburgh, January 11th 2007
– p.18/28
Introduction
Target Simulation
Cost of the Simulations
B-Physics
Conclusions
Outline of Talk
In this talk I ask the question
Will we be able calculate hadronic parameters with a 1% precision by
2015?
1. Introduction
2. Required Parameters for 1% Precision.
3. Scaling Laws and Costs of Simulations.
4. B-Physics.
5. Conclusions.
I have made extensive use of
1. V.Lubicz – CKM Fit and Lattice QCD, presented at SuperB IV, Monte
Porzio Catone, 2006.
2. S.Sharpe – Weak Decays of Light Hadrons, presented at Lattice QCD,
Present and Future, Orsay, 2004.
Lattice Phenomenology
Patricia Ball
LHCb Upgrade Workshop, Edinburgh, January 11th 2007
– p.19/28
Introduction
Target Simulation
Cost of the Simulations
B-Physics
Conclusions
3. Cost of the Simulations
At the 2001 Lattice Conference in Berlin, Ukawa presented an estimate
of the CPU cost of generating 100 independent configurations for
Nf = 2, O(a) improved Wilson quarks on a L3 × 2L lattice:
5
0.2
m̂/ms
3 L
3 fm
5 0.1 fm
a
7
TFlops-Years .
This has become known as the Berlin Wall.
Cost @TFlops-YearD
2
L
=
2.5 fm,
1.5
a
=
0.08 fm,
1
V
=
323 × 64 .
0.5
0.1
Lattice Phenomenology
Patricia Ball
0.2
0.3
0.4
0.5
0.6
mms
LHCb Upgrade Workshop, Edinburgh, January 11th 2007
– p.20/28
Introduction
Target Simulation
Cost of the Simulations
B-Physics
Conclusions
Cost of the Simulation – Cont.
The CERN Group using the DD-HMC algorithm find that the
corresponding cost is
5 6
1 0.2
L
0.1 fm
.05
TFlops-Years .
m̂/ms
3 fm
a
L.Del Debbio et al., [hep-lat/0610059]
This is a huge improvement on the Berlin Wall:
0.2 3
L 5 0.1 fm 7
5
TFlops-Years .
m̂/ms
3 fm
a
Cost @TFlops-YearD
2
L
=
2.5 fm,
1.5
a
=
0.08 fm,
1
V
=
323 × 64 .
0.5
0.1
Lattice Phenomenology
Patricia Ball
0.2
0.3
0.4
0.5
0.6
mms
LHCb Upgrade Workshop, Edinburgh, January 11th 2007
– p.21/28
Introduction
Target Simulation
Cost of the Simulations
B-Physics
Conclusions
Estimates of Lattice Errors in 2015
V.Lubicz
Measured
Quantity
CKM
Matrix
Element
Hadronic
Matrix
Element
Current
Error
Estimated
Error in
2015
K → π `ν
|Vus |
fK+π (0)
0.9%
<0.1%
εK
B → `ν
2
Im Vtd
|Vub |
22% on 1 − fK+π (0)
2.4% on 1 − fK+π (0)
11%
14%
1%
1-2%
14%
1-2%
∆md /∆ms
|Vtd /Vts |
5%
0.5-0.8%
25% on ξ − 1
3–4% on ξ − 1
4%
0.5%
40% on 1 − F
5% on 1 − F
11%
2–3%
13%
3–4%
∆md
ξ
B → D/D∗ `ν
|Vcb |
FB→D/D∗ `ν
B → π /ρ `ν
|Vub |
fB+π , · · ·
B → K ∗ /ρ (γ , `+ `− )
Lattice Phenomenology
Patricia Ball
|Vtd |
BK
fB
p
fBd BBd
|Vtd /Vts |
T1
LHCb Upgrade Workshop, Edinburgh, January 11th 2007
– p.22/28
Introduction
Target Simulation
Cost of the Simulations
B-Physics
Conclusions
5. Summary and Conclusions
Access to PFlops CPU power + current knowledge and techniques ⇒
O(1%) precision on hadronic parameters.
It is likely that further theoretical and technical improvements will
improve the precision still further.
For B-Decays into two-hadron states (or states with a higher numbers of
hadrons) we need new ideas before we can formulate the problem of the
numerical evaluation of the amplitudes.
Lattice Phenomenology
Patricia Ball
LHCb Upgrade Workshop, Edinburgh, January 11th 2007
– p.23/28
New Physics in Heavy Flavours
LHCb Upgrade Workshop
Edinburgh – January 11, 2007
Yossi Nir (Weizmann Institute of Science)
Patricia Ball
– p.24/28
Concluding
Accurate
dataQuestions
base
Is there new flavor physics?
A worthy goal: better than 1% precision on flavor physics
• Alternatives to CKM:
O(1) effects - excluded by present data
• Subdominant new sources of flavor/CP violation:
O(10%) effects explored at present (hints for b → s?)
• Minimal Flavor Violation:
O(m2W /Λ2NP ) ∼ 1% effects
Where is theory better than 1%? SψKS ...
• Measure γ via B → DK modes
• Measure/improve B, ACP , AFB for B → Xs γ and B → Xs `+ `−
• Measure KL → πν ν̄
Patricia Ball
– p.25/28
Open questions
Conclusions
• The O(1) questions have been answered
The O(0.1) questions are being explored
The O(0.01) questions pose a worthy goal
• Corrections to CKM are possible
• Charm (and top?) may provide NP surprises
a K + K − , aπ + π −
• b → s has always been a suspect
improved accuracy can reveal NP
• γ from B → DK can stregthen our tests
• There is still much to be learned from flavor/CP physics
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– p.26/28
For your info. . .
Patricia Ball
– p.27/28
UK HEP FORUM:
Heavy Flavour Physics
Cosener’s House, Abingdon on Thames
June 21-22nd, 2007
ƒ Heavy flavour and new physics
ƒ B decays in BSM scenarios
ƒ Benchmarks and Tools
ƒ Future experiments/facilities
Organizing committee:
Patricia Ball
Francesca Di Lodovico
Bill Murray
Steve Playfer
Stefania Ricciardi
Chris Sachrajda
Secreteriat:
J.Bruffel@rl.ac.uk
Registration: http://hepwww.rl.ac.uk/accel/forum/2007b/forum.html
Patricia Ball
– p.28/28