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Beauty Physics at LHCb

b
p                            p
b
Andrey Golutvin

ITEP & CERN

11th INTERNATIONAL MOSCOW SCHOOL OF PHYSICS
Session «Particle Physics» February 8-16, 2008
Outline

 ABC of LHC

1    Flavor physics – informal introduction
 The CKM matrix and Unitarity Triangle
 LHCb detector
 Search for New Physics in CP violation
2    Physics of loops
 Rare decays at LHCb
 Conclusions
Jet d’ Eau     Mont Blanc,
LHCb experiment:    140 m          4808 m
700 physicists
50 institutes
15 countries

CERN
LHCb

ATLAS

CMS
ALICE
ABC of LHC

• Tonnel length - 27 kilometers

• Depth below ground - between 50 and 175 meters

•   p-p beams, 2808 bunches, 1.15×1011 particles/bunch

• v = 0.99999998 c

• Energy        s  14 TeV        Etotal  200 Etotal
LHC          Tevatron

• Nominal luminosity <L> ~ 1034 cм-2 сек -1
Energy of a proton in the beam = 7 TeV = 10-6 J
It is about kinetic energy of a flying mosquito:

Question: why not to use mosquitos in particle physics?

Energy of a mosquito is distributed among ~ 1022 nucleons.
On the other hand, total energy stored in each beam is
2808 bunches  1011 protons/bunch  7 TeV/proton = 360 MJ
It is explosive energy of ~ 100 kg TNT or kinetic energy
of “Admiral Kuznetsov” cruiser traveling at 8 knots.
Particle acceleration
 Charged particles influenced by applied electric and magnetic fields
according to the Lorentz force: F = q (E + v  B) = dp/dt
E field → energy gain, B field → curvature
 CERN has a wide variety of accelerators, some dating back to 1950s
 LHC machine re-uses the tunnel excavated for previous accelerator (LEP)
Others (PS/SPS) used to accelerate protons before injection into the LHC

Neutrino beam,
low energy beams
and p fixed-target
beams all running
in parallel with LHC
The LHC
From an article in the CERN Courier   Original idea

Reality
• Dipole magnets used to deflect the particles
Radius  [m] = 3.33 p [GeV] / B [T]
• For the LHC, the machine has to fit in the
existing 27 km tunnel, about 2/3 of which is
used for active dipole field →  ~ 2800 m
So to reach p = 7 TeV requires B = 8.3 T
• Beams focused using quadrupole magnets
By alternating Focusing and Defocusing                    The LHC has 1232 dipoles
quadrupoles, can focus in both x and y views                      392 quadrupoles

y
N-pole        S-pole

Beam
x
S-pole        N-pole
View of LHC tonnel
Flavor physics:
informal introduction
The Standard Model Zoo
SU(3)SU(2)U(1) [ g; W, Z; ]

u    c    t 
 
d     
s     
b
           

e         
 
     
     
 
 e        

Mass hierarchies (from hep-ph/0603118). The
heaviest fermion of a given type has unit mass.

Masses come out of interactions in the Standard Model
and these interactions conserve (or do not conserve…)
particular symmetries.
Invariance properties with respect to transformations
have been always important in physics
3
1. translations in    R            1. momentum
3
2. rotations in   R                2. angular momentum

3. time translations               3. energy

invariance                       conservation

Gauge symmetry – invariance with
respect to transformations in
«internal» space

In the SM this space has structure of U(1) × SU(2) × SU(3)
U(1) × SU(2) × SU(3)
photon             Z, W         gluon
And gravity is
everywhere

leptons

quarks

Quarks are unique probes of the whole
«internal space», hence flavor physics has
to deal with weak, electromagnetic and
strong interactions altogether
Besides continuous symmetries of prime importance in
high energy physics are discrete transformations

• С – charge conjugation
• P – space inversion
• Т – time reflection

Experimental fact: strong and electromagnetic interactions
in the SM are C, P, T, CP, CT, PT and CPT invariant.
Maximal symmetry is not so interesting…

Beauty         slightly broken symmetry
The breaking should not be too strong, however…
СРТ theorem:
Antiparticles and their interactions are indistinguishable from
particles moving along the same world-lines but in opposite
directions in 3+1 dimensional space-time.

In particular, the mass of any particle is strictly equal to the mass of its
antiparticle (experimentally checked in 1 part to 1018 in K-meson studies).

The SM strictly conserves CPT. There are no however any
theoretical reason why C, P and T should conserve
separately.

Often in physics if something can happen – it does.
Weak interactions violate P-parity

T.D.Lee, C.N.Yang, 1956                C.S.Wu, 1957
L.D.Landau, 1959:    J.Cronin, V.Fitch, 1964: CP-violation
hypothesis of        discovery in neutral K-mesons
combined CP-parity   decays.
conservation
In the world of elementary particles:
(CPLEAR 1999)

neutral kaon
decay time distribution

anti-neutral kaon
decay time distribution

CP violation
Later CP-violation has been beautifully measured by experiments
BaBar and BELLE at the B factories

These are machines (in the US and Japan) running on the (4S)
resonance: e+e-  (4S)  B0B0 or B+B-
 The CP asymmetry A(t) = G(B0  J/y KS) - G(B0  J/y KS)
G(B0  J/y KS) + G(B0  J/y KS)
A(t) = - sin2b sin Dm t
in the Standard Model
 BABAR+BELLE measure
sin2b = 0.674 ± 0.026
 This can be compared with
the indirect measurement
from other constraints on the
Unitarity Triangle
M. Kobayashi, T.Maskawa, 1974:
theoretical mechanism for
CP-violation in the SM

Idea: nontrivial superposition of non-interacting particles
forms flavor eigenstate that interacts weakly

In other words: it is impossible to diagonalize simultaneously
the mass term and charged currents interaction term:

 dL 
  +
Lint 
g2
u L , cL , t L  VCKM  sL W + h.c.
 ˆ

2                         b 
 L
 d '  Vud       Vus Vub  d 
                         
 s '    Vcd    Vcs Vcb  s 
 b'   V                  b 
   td           Vts Vtb  
It is easy to show that arbitrary complex unitary N×N
matrix can be parameterized by N(N-1)/2 generalized
Euler angles and (N-1)(N-2)/2 complex phases.

For N<3 the matrix can always be rotated to an equivalent
one which is real. But not for N=3.

In other words, there exist 3×3 unitary matrices which cannot
be made real whatever phases quark fields are chosen to have.
Baryogenesis

 Big Bang (~ 14 billion years ago) → matter and antimatter equally
produced; followed by annihilation → nbaryon/ng ~ 10-10
Why didn‟t all the matter annihilate (luckily for us)?
 No evidence found for an “antimatter world” elsewhere in the Universe
 One of the requirements to produce an asymmetric final state (our
world) from a symmetric matter/antimatter initial state (the Big Bang)
is that CP symmetry must violated [Sakharov, 1967]
 CP is violated in the Standard Model, through the weak mixing of quarks
For CP violation to occur there must be at least 3 generations of quarks
So problem of baryogenesis may be connected to why three
generations exist, even though all normal matter is made up from the
first (u, d, e, e)
 However, the CP violation in the SM is not sufficient for baryogenesis
Other sources of CP violation expected → good field to search for new
physics                                                               24
CKM matrix can be parameterized by four parameters in many
different ways. The so called «Wolfenstein parametrization» is
based on expansion in powers of

  Vus + O( )  0.2272  0.0010
7
It is convenient to discuss the properties of CKM matrix
in parametrization-invariant terms. Such invariant are
absolute values of the matrix elements and «angles»
between them

 VijVik 
*

  arg
V V

* 
 lj lk 

If any of these angles is different from zero, it means that
there is a complex phase in CKM matrix which cannot be
rotated away. This violates CP.

«Jarlskog invariant»      J  Im ViV jb Vib V j* ~ 3 10 -5
*
Off-diagonal unitarity conditions can be represented as
triangles on complex plane.

Vud Vus Vub                    Vud Vub + Vcd Vcb + Vtd Vtb  0
             
*          *          *

 Vcd Vcs Vcb                   Vud Vtd
*
+ Vus Vts + Vub Vtb
*          *
0
V            
 td Vts Vtb                         The Unitarity triangle:

All 6 unitarity triangles have
equal area but only two of                  *                    *
VtdVtb
V V
ud ub
them are not degenerate.
                 b
B-mesons decays are                                      *
very sensitive to СР !
VcdVcb
The Unitarity triangle
 ,   1 - 2 2 ,                                         b: Bd mixing phase
Im                        B0   ,  ,  ,.....
                                      *
VtdVtb                       : Bs mixing phase
                     *                       : weak decay phase
VcdVcb
VudVub*                                            B 0  J /yK S , .....
0

*
Vcd Vcb                                 b
0                                         1 Re                       *
Im                                   VudVtd
Bd  DK , DK *                                                                      *
Bs  Ds K              - 2         *

Vcd Vcb
Bs  J /y, .....
0
VubVtb
Bd  D*               + 2b             *

Vcd Vcb
-                         b+
Precise determination
of parameters through                             0                    *           *            Re
B-decays study.                                                       VusVts / VcdVcb
UT as a standard approach to test the consistency of SM

Mean values of angles and sides of UT are
consistent with SM predictions

Accuracy of sides is limited by theory:

- Extraction of |Vub|

- Lattice calculation of

Accuracy of angles is limited
by experiment:

= ± 13°
b = ± 1°
 = ± 25°

29
Standard method to search for New Physics

Define the apex of UT

using at least 2 independent quantities out of 2 sides:

and 3 angles: , b and 

Extract quantities Rb and  from the tree-mediated processes,
that are expected to be unaffected by NP, and compare computed
values for

with direct measurements in the processes involving loop graphs.

Interpret the difference as a signal of NP
Topologies in B decays
Trees
b                        q1

q2
Bq              W−
d, s

Penguins
W–
W−                                   W−
b                  q                                  d (s) b              u,c,t   d (s)
u, c, t        b               u, c, t
l+                        q
Z, γ                                 g
l−                        q
Boxes
V*ib              Viq
b                 u,c,t                   q
Bq            W+                   W−              Bq
q                  u, c, t                 b
Viq               V*ib
Standard method to search for New Physics

Define the apex of UT

using at least 2 independent quantities out of 2 sides:

and 3 angles: , b and 

Extract quantities Rb and  from the tree-mediated processes,
that are expected to be unaffected by NP, and compare computed
values for

with direct measurements in the processes involving loop graphs.

Interpret the difference as a signal of NP
The sensitivity of standard approach is limited due to:

- Geometry of UT (UT is almost rectangular)
Comparison of precisely measured b with  is not meaningful due to error
propagation: 3° window in b corresponds to (245)° window in 
Precision comparison of the angle  and side Rt is very meaningful !!!

However in many NP scenarios, in particular with MFV, short-distance
contributions are cancelled out in the ratio of DMd/DMs.
So the length of the Rt side may happen to be not sensitive to NP

Precision measurement of  will
effectively constrain Rt and thus
calibrate the lattice calculation
of the parameter
Complementary Strategy

*
Compare observables VtsVtb and UT angles: , b and 
measured in different topologies:

In trees:

Theoretical uncertainty in Vub extraction

*
Set of observables for VtsVtb (at the moment not theoretically clean):

Theoretical input: improved precision of lattice calculations
for fB , BB and B,,K* formfactors
Experimental input: precision measurement of BR(BK*, )
Search for NP comparing observables
measured in tree and loop topologies
b(tree+box) in B J/y Ks            (peng+tree) in B,,
(tree) in many channels             b(peng+box) in B Ks
(tree+box) in Bs J/y              (peng+box) in Bs 

New heavy particles, which may contribute to d- and s- penguins,
could lead to some phase shifts in all three angles:

(NP) = (peng+tree) - (tree)
b(NP) = b(BKs) - b(BJ/yKs)    ≠     0
(NP) = (Bs) - (BsJ/y)
Search for NP comparing observables
measured in tree and loop topologies

Contribution of NP to processes mediated by loops
(present status)

 to boxes:

b vs |Vub / Vcb | is limited by theory (~10% precision in |Vub|)   (d-box)
 not measured with any accuracy                                   (s-box)

 to penguins:

((NP)) ~ 30°                       (d-penguin)
(b(NP)) ~8°                          (s-penguin)
((NP)) not measured                (s-penguin)

PS    b(NP) =  (NP)
(NP) measured in B and B decays may differ depending
on penguin contribution to  and  final states

37
LHCb is aiming at search for
New Physics
in CP-violation and Rare Decays
Large Hadron Collider - LHCb
• Bunch crossing frequency: ~ 40 MHz
• Number of reactions in unit of time:
N bunches                   Inelastic pp reactions
N  L              N react
T                bunch

since pp inelastic ~ 80 mbarn
for nominal LHC luminosity
N ~ 8108 N react        20
bunch
• For LHCb L ~ 2 × 1032 cm-2s-1
(local defocusing of the beam)
→ multi-body interactions are
subdominant
-                                       b
bb angular
distribution                             b
b
b

100μb

230μb

Pythia

• vertices and momenta reconstruction
• effective particle identification (π, К, μ, е, γ)                             η of B-hadron
• triggers
View of the LHCb cavern

Calorimeters
Magnet
Muon detector                  RICH-2    OT

RICH-1

VELO

It’s full!
Installation of major structures is essentially complete
LHCb in its cavern
Offset interaction point (to make
Shielding wall
best use of existing cavern)

Electronics
+ CPU farm

Detectors can be moved
away from beam-line
for access
LHCb detector

p               p                                           10 mrad


Forward spectrometer (running in pp collider mode)
Inner acceptance 10 mrad from conical beryllium beam pipe
LHCb detector


Vertex locator around the interaction region
Silicon strip detector with ~ 30 m impact-parameter resolution
•
Vertex detector
Vertex detector has silicon microstrips with r geometry
approaches to 8 mm from beam (inside complex secondary vacuum system)
•   Gives excellent proper time resolution of ~ 40 fs (important for Bs decays)

Beam

Vertex detector information is used in the trigger
LHCb detector


Tracking system and dipole magnet to measure angles and
momenta Dp/p ~ 0.4 %, mass resolution ~ 14 MeV (for Bs  DsK)
LHCb detector



Two RICH detectors for charged hadron identification
LHCb detector

e

h


Calorimeter system to identify electrons, hadrons and
neutrals. Important for the first level of the trigger
LHCb detector




Muon system to identify muons, also used in first level of trigger
S :     LHC prospects

Bs J/y is the Bs counterpart of B0J/y KS
 In SM S = - 2arg(Vts) = - 22 ~ - 0.04
 Sensitive to New Physics effects in the Bs-Bs system          if NP in
mixing  S = S(SM) + S(NP)
 2 CP-even, 1 CP-odd amplitudes, angular analysis needed to
separate, then fit to S, DGS, CP-odd fraction
 LHCb yield in 2 fb-1 131k, B/S = 0.12

LHCb

0.021
0.021

ATLAS       will reach s(s) ~ 0.08 (10/fb, Dms=20/ps, 90k J/y evts)
UT angle  : LHCb               (BaBAr & BELLE & Tevatron ~12° precision for  at best)

 Interference between tree-level decays
Favored: Vcb Vus*                                                        Vcs* Vub: suppressed
s                                   u
K(*)-      Common       K(*)-   s
b                           u                                                     u
B-                                             final state                                 B-
u                           c                                   c                 b
u   D(*)0                   D(*)0   u
f

A B - D 0 K -        r ei e -i                     Parameters: γ,
AB                  B
B
-
D0 K -                                      (rB, δB) per mode

Three methods for exploiting interference (choice of D0 decay modes):
 (GLW): Use CP eigenstates of D(*)0 decay, e.g. D0  K + K- / π+π– , Ksπ0
 (ADS): Use doubly Cabibbo-suppressed decays, e.g. D0  K+π -
 (Dalitz): Use Dalitz plot analysis of 3-body D0 decays, e.g. Ks π+ π-

 Mixing induced CPV measurement in Bs  Ds K decays
Specific for LHCb
UT angle  : LHCb summary table

Combined precision after 2 fb-1 ()  5 (from tree only)
LHCb (10fb-1 ) and SFF (50-75 ab-1) & SLHCb (>100 fb -1) sensitivities

Channel               Yield          Precision
LHCb              From tree channels                   () < 3

    Bd +-0                 70k       () < 4
B  +0, +-,00   45k,10k,5k

b    Bd  J/y()KS            1200k      (sin2b) < 0.01
Bd  KS                    4k       (sin2b) ~ 0.1

s   Bs  J/y()                 750k   (s) ~ 0.01
Bs                          20k   (s) ~ 0.05

SFF & SLHCb                                                                    SLHCb (stat. only)
~ 0.003
> 2014                                                                        < 1 (BsDsK)
-
-
-

S(K0S) 0.02-0.03
S()   0.01
Physics of loops

Loops can be also explored in rare decays. But before
discussing LHCb prospects let us take more general
attitude and ask ourselves: why is it important to study
loop processes in general?
Main reason is the following: loop physics is intimately related
to overall integrity and the deepest features of quantum theory
(Heisenberg uncertainty principle, unitarity, causality etc).

Example: optic theorem & all that

i  f               f Si         SS +  1      S 1 + iT
f

1  n n                      2 Im T  T  T     +

n

Im T  Re T
i 2 Im T i   i T n
Sum over                                2
everything!                                      by means of dispersion
n                    relations (causality)


2
At order e2                                  Each green arrow is nontrivial.
Deep relations between
n                     trees and loops.
Loop processes contain loop momentum integrals
and hence can indirectly probe physics at large mass scale
Example: quantum electrodynamics at small distances or
in strong fields is sensitive to the electron mass in loops
a) the potential between static sources deviates from Coloumb
law at small distances:
  2      1 
+                   V (r )  1 +  log       
r  3     cme r 
b) the energy stored by the static magnetic field is different
from its classical value: H 2 / 2
H 2   2H 2 
 classic +                         1 -       
2  45 me4 
Analogously rare B-decays mediated by loop processes
are sensitive to heavy particles masses and couplings:
logarithmically for radiative penguins and power-like for
box diagrams. However the concrete form of functional
dependence is much more complicated than in considered
simple examples.
Loop processes contain sums over all relevant degrees
of freedom (Lorentz structure of the interaction, symmetries
related to New particles etc…).

Example: neutral kaon oscillations
Neutral K-mesons made of d and anti-s quarks oscillate in
vacuum with the frequency ~ 1010 sec-1 because of the
following loop process, mediated by “box” diagram:

s           u, c, t          d
K0     W+                  W−       K0
d           u, c, t          s
Viq             V*ib

Notice that it is the same diagram which describes oscillations
of B-mesons if we replace s-quark by b-quark!
Suppose we know nothing about the existence of heavy
c- and t-quarks.
Then naïve estimate of the box diagram with one internal
u-quark gives for the level splitting Dm12 (which is nothing
but the oscillation frequency)
Dm12
G2 ~ 2     ~ GF  M W ~ 10 -6 GeV - 2
2     2

f K mK
while experimental result is G2 ~ 10 -13 GeV -2 It seems we
have a problem…
Solution: GIM - S.Glashow, J.Iliopoulos, L.Maiani, 1970
Box diagram with internal c-quark cancels the one with
u-quark (up to the quarks mass difference):
2
GF
G2 ~       (mc - mu ) 2 sin 2  cos 2 
16 2
Comparison of calculated G2 with experimentally measured
Dm12 leads to correct prediction for mc ~ 1 GeV
This is how it actually happened: GIM mechanism was suggested in 1970,
while direct experimental discovery of c-quark took place only in 1974!
Historical remark #1. Perhaps even more spectacular is that the famous
Kobayashi-Maskawa paper where the quarks of third generation (b- and
t-quarks) and current paradigm of CP-violation were introduced was
also published a few months before c-quark discovery (and about four
years before b-quark discovery).
Historical remark #2. Original idea about possible fourth quark (c-quark)
Was suggested by M.Gell-Mann in his original ’1964 paper devoted to the
quark model with three light quarks (u-, d-, and s- quarks) on aesthetic
grounds of symmetry between quarks and leptons.
Historical remark #3. The analogous mixing matrix in lepton sector was
proposed by Z.Maki, M.Nakagawa and S.Sakata in 1962, i.e. well before
CKM!
Computation of Loop processes

Main theoretical tool here is the formalism of effective
low-energy ( μ << MW ) Hamiltonians

f H   DF 1
eff     i 
GF *

V fjVij        C ( ) 
k          f Ok (  ) i
2                 k

Notice that full Hamiltonian is μ-independent! (at each order in αs)

In Wilson’s operator product expansion the quantities                    –
coefficient functions – take into account physics at large
scales p > μ, while local operators        care about
low energy (p < μ) physics.
New Physics can manifest itself both via corrections to SM
coefficient functions (the so called «minimal flavor violation»
scenario) and via new operators.
How does it work in practice?

Simple example – Fermi interaction
gW
μ-                                                          νμ
In the SM muon decay is
W-
described by the diagram                                                     gW         e-
νe
The corresponding amplitude
2                            There are two different scales:
g
e   (1 -  5 ) e         W
    (1 -  5 )     M W  6.5  10 3 GeV 2 and
2

q 2 - MW
2
q 2 ~ m  1.110-2 GeV 2
2

2
gW    8G
Thus one can replace 2       F                                                                   νμ
q - MW
2
2
G                                                                               GF
A  F  8  [e   (1 -  5 ) e     (1 -  5 )  ]         μ   -
e-
2
-5             -2        νe
(factor 8/√2 is of historical origin)             GF  1.166 10 GeV
Not so simple example – neutral B-mesons mixing.
This process is described by «box» diagrams

The corresponding effective Hamiltonian has the form
(leading order in QCD coupling) :
        
2
GF
M W VtbVtd S0 ( xt )[b   (1 -  5 )q  b   (1 -  5 )q]
2
D
H effB  2             2   *

16  2

coefficient
function
M.Vysotsky, „80                                               local
T.Inami, C.Lim,„81                                          operator
Rare decays of main interest at LHCb
radiative «penguin» decays B → K* γ, Bs → φ γ, B → Kφγ,
related mode B → K* μμ and «box» decays, notably Bs → μμ

Name «penguin» was coined by John Ellis in 1977 as a result of the
darts bet between him and Melissa Franklin…

Different views
b  s exclusive

Bs 
LHCb control channel: Bd  K*     BELLE observed 16±8 events
~75k signal events per 2fb-1     2 weeks run at (5S); no TDCPV

LHCb annual yield ~11k
with B/S < 0.6
The effective Hamiltonian for these processes has the form:

In the SM

Thus the photons are dominantly right-handed in the decays
of B-mesons and left-handed in the decays of anti-B mesons

Real life is a little bit more complicated, npQCD corrections
also contribute to “wrong” helicity amplitude… But not much.
Consider angular momentum book-keeping
at the quark level. In s-quark rest frame (pb = pγ) we have:

s 
b                    or
s 
b
But coupling between bL and bR in this frame (and hence the ratio
γL / γR ) is proportional to small parameter mb    ms
~
pb       mb
Bs → φ γ
Due to the mixing between Bs and anti-Bs two states
with the masses m1 , m2 and widths Γ1 , Γ2 are formed.
The time-dependent decay width with CP-eigenstate and
a photon at the final state is given by

where ΔΓq = | Γ1 - Γ2 | and Δmq = | m1 - m2 | for q =s or d

where

if neither     nor       is small (in SM CKM angle     )
– we have a chance to find from the time-dependent rate.

This is exactly the case of Bs mesons.
b  s exclusive (will be presented by Lesya Schutska)
Mixing induced CP asymmetries

 BKs0  (B-factories)

S = - (2+O(s))sin(2b)ms/mb + (possible contribution from bsg) = - 0.022 ± 0.015
P.Ball and R.Zwicky hep-ph/0609037
Present accuracy:
S = - 0.21 ± 0.40 (BaBar : 232M BB)
S = - 0.10 ± 0.31 (BELLE: 535M BB)

 Bs   (LHCb)

LHCb sensitivity with 10fb-1 :
b  s exclusive

Measuring the photon polarization in
B  h1h2h3  decays

The measurement of the photon helicity requires the knowledge of the spin
direction of the s-quark emitted from the penguin loop. Use the correlation
between s-spin and angular momentum of the hadronic system (needs partial-
wave analysis !!!)

Promising channels for LHCb:                                   Expected yield
per 2 fb-1

BR(B+  K+-+) ~ 2.5  10-5 rich pattern of resonances              ~60k
BR(B+  K+) ~ 3  10-6      highly distinctive final state         ~ 7k

Sensitivity to photon helicity measurement is being studied
B  [  KK ]K
The b-quark from initial B meson decays into a photon and s-quark.
The latter forms the hadron system Y (together with the spectator),
which is characterized by total angular momentum J and its
projection. Strong dynamics causes consequent decay of Y into a
pseudoscalar meson (where the spectator quark goes) and a vector
or tensor (where the s-quark goes).

s
             s
s
P
Y (J )             b          B
K
q
If only s-wave contributes, Clebsch-Gordan coefficients
are trivial (=1) and there is no sensitivity to λ.

Introducing helicity factor as
dΓ/dΦ can be rewritten as

If J = 1 contributions dominate:
B  K* (will be presented by
William Reece)

In SM this bs penguin decay contains
right-handed calculable contribution
but this could be added to by NP resulting
in modified angular distributions

SM
B → K* μμ

?
A very important property is   ..and position of its zero,
forward-backward asymmetry..   which is robust in SM:
AFB(s), fast MC, 2 fb–1

eff
2C7
s0  - eff
C9 (s0 )           s = (m)2 [GeV2]
B  K*:      LHCb prospects

 Forward-backward asymmetry AFB (s) in -
rest frame is a sensitive NP probe
 Predicted zero of AFB (s) depends on Wilson
coefficients C7eff / C9eff

AFB(s), fast MC, 2 fb–1

 7.2 k events / 2fb-1 with B/S ~ 0.4
 After 10 fb-1zero of AFB located to ±0.28
GeV2 providing 7% stat. error
on C7eff / C9eff
 Full angular analysis gives better
discrimination between models. Looks
promising
s = (m)2 [GeV2]
Bs                                  Will be presented by Diego
Martinez Santos

Very smal BR in SM
(3.4 ± 0.5) x 10-9

This decay could be strongly enhanced
in some SUSY models. Example: CMSSM

Current limit from CDF
BR(Bs) < 5.810-8

LHCb

79
OUTLOOK
Clean experimental signature of NP is unlikely at currently operating experiments

From now to 2014
A lot of opportunities (LHCb will start data taking this summer)
Important measurements to search for NP and test SM in CP violation
 : if non-zero  NP in boxes < 2010
 b vs Rb and  vs Rt (Input from theory !)
 b(NP) and (NP): if non-zero  NP in penguins
in Rare decays
 BR(Bs  ) down to SM prediction < 2010
 Photon helicity in exclusive bs decays
 FBA & transversity amplitudes in exclusive bsll decays     < 2010

After 2014
ATLAS and CMS might or might not discovered New Particles. At the same time
LHCb might or might not see NP phenomena beyond SM.
In either case it is important to go on with B physics at SFF & Upgraded LHCb

high pT                    B’s

Need much improved precision because any measurement
in b-system constrains NP models

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