B factoriesB factories - unizar.es · 2020. 9. 9. · CP violation in charm? Observation of many...

B factoriesB factoriesXXXIX IMFP

7th to 11th February 2011LSN Canfranc Underground Laboratory

F. Martínez‐VidalIFIC – Universitat de València‐CSIC

OutlineFlavor Physics in the quark sectorB factoriesB factories CP violation and CKM in B mesonsSearches for New Physics Reason d’être of the B factories…Searches for New PhysicsSummary and perspectives

Many more measurements and observations not discussed here: Lepton flavor violation Lepton flavor violation Observation of many new states: b(1S); e.g. Ds0

*(2317); charmonium-like states (X, Y, Z families)

Tau and charm physics Tau and charm physics …

This talk sketches some topics of the work of many people, over

1B factoriesIMFP 2011, LSC

This talk sketches some topics of the work of many people, over more than one decade, from ~800 publications

del

Flavor Physics in the Standard Model (SM) in the quark sector

10 free parameters 6 quarks masses

4 CKM parametersf of the

ard Mod

p

~ half

Stan

da

Wolfenstein parametrization : ,A, responsible of CP violation in SM

In the SM, charged weak interactions among quarks are codified in a 33 unitarity matrix , the CKM Matrix

This matrix conveys the fact that the quarks i i i i k li

Th f i i l i d b SM Hi M h i

participating in weak processes are a linear combination of mass eigenstates

The fermion sector is poorly constrained by SM + Higgs Mechanismmass hierarchy and CKM parameters


Flavor Physics in the quark sector of the Standard Model (SM)

Flavor Physics has played a key role in the history of Particle Physics

“Discoveries” and construction of the SM Lagrangian

1970 Charm quark from FCNC and GIM mechanism K0 1973 3rd generation from CP violation in kaon ( ) KM mechanism

Discoveries and construction of the SM Lagrangian

1973 3rd generation from CP violation in kaon (K) KM-mechanism 1974 Discovery of the J/ meson, the first excited state of a cc bound state 1976 Discovery of the neutral D meson 1977 First speculations on charm mixing and CP violation in charm 1978 Discovery of the (4S) meson, excited state of a bb bound state 1983 Discovery of the neutral and charged B mesons1983 Discovery of the neutral and charged B mesons 1990 Heavy top from B oscillations mB

2001era

2001…

factoriese

B f



… Success of the description of FCNC and CPV in SM

Dominated byDominated by md, Vub,Vcb, K, limit on ms and Lattice

B factories

The first fundamental test of agreement betweendirect and indirect measurements of sin2

To precisionera

A single irreducible phase in the weak interaction (CKM) matrix accounts for most of the CP violation

4

observed in kaons and B’s

B factoriesIMFP 2011, LSC


… Success of the description of FCNC and CPV in SM

Dominated byDominated by md, Vub,Vcb, K, limit on ms and Lattice

The first fundamental test of agreement betweendirect and indirect measurements of sin2

A single irreducible phase in the weak interaction (CKM) matrix accounts for most of the CP violation

4

observed in kaons and B’s


B physics and CKM B physics probes the range and phases of 3rd

generation CKM elements through both tree and one loop processesand one-loop processes

Angles related to CP violation measurements Lengths of sides related to magnitudes of CKM elements (i.e. CP g g (

conserving measurements) Redundant determinations of the 4

parameters using theoretically and experimentally independent methods

B

experimentally independent methodso CP conserving: |Vus|, |Vcb|, |Vtd|, |Vub|o CP violating: , , K, sB ...o Tree level: …, |Vub|, o Loop level: …, |Vtd|,

Validate methodology and interpret to

B DK B J/K0

Validate methodology and interpret to search for new physics

15

B DK+other charmonium +from PenguinsB J/K


CKM phases measurable when there are two paths to reach the same final state, and

Measuring the phases from CPVp p ,

strong phases do not vanish

weak strong2 2 2

1 2 1 2

2 2 2

| ( ) | | | | | 2 | || | (cos )A B f A A A A

Text book example: interference between B0J/KS (bccs) and B0J/KS(b cs) d ll d t i ti f

we str2 2 2

ong2 ak1 2 1| c( ) | | | | | ( )|| o| s2 |A B f A A A A

(bccs) decays allows determination of

mixing decay mixing decayg y

etry

Next largest amplitude (2) has same weak phaseOther CKM corrections are Cabibbo suppressed O(4)

0 0( ) ( )( ) ( ) i ( )B fB f

t tA C S

21 | |f 2Imi 2f

CP asymm 2/ ip q e

fq Aλ

0 0CP, ( ) cos( ) sin( )

( ) ( ) f ffB f

fB fB f

A t m t m tt t

C S

Uncertainty ~1%

2

| |0

1 | |f

f 2 sin 2

1 | | CP

ff

f

C ffp

λA

and depend on the CKM anglesf fS C


B Flavor

The asymmetric B factory conceptB‐FlavorTagging

K

Tagging performance: Q=(1 2w)2~30%

(4 )0.425 0.56S

e-e

tagB 4S Tag vertex reconstruction

K Q=(1‐2w)2~30%

(3 1 GeV)e

recB /J

(9.0 GeV)(3.1 GeV)

Coherent B meson production (L=1)

z ~250 m

0SK

production (L=1)

zt 1

Exclusive B Meson and vertex reconstruction

Start the Clockc

Δt is a signed quantity

reconstruction

1 ps 170 m

High‐statistics self‐tagging“B‐flavor” sample to lib i~ 1 ps 170 mt calibrate taggingmeasure z resolution


Additional experimental techniques Veto significant/potentially dangerous B decay backgrounds Veto significant/potentially dangerous B decay backgrounds Resonance masses, decay angles, helicity in

PPV, VPP decays Suppress continuum e+eqq (q=u,d,s,c) background

using event topology (multivariate methods)

In general, search for a needle in a haystack

Characterize B candidates usingg Beam-energy substituted mass Energy difference

Maximum likelihood fits to mMeV

BEE 5010~ * Maximum likelihood fits to mES,

E, Fisher, PID, t, tagging, etc Use sidebands and control samples

to check backgrounds MeVbeammES7.2~~


BaBar detectorDIRC PID)

144 quartz bars11000 PMs

1.5T solenoid EMC6580 CsI(Tl) crystals

11000 PMs

e+ (3.1 GeV)

Drift Chamber40 stereo layers

Silicon Vertex Tracker5 layers double sided strips

e- (8-9 GeV)Instrumented Flux Return

iron / RPCs / LSTs (muon / neutral hadrons)

5 layers, double sided strips


Belle detector


B factoriesB factories, luminosity frontier…

Precision era

~ 109 BB, DD, pairs≈ 1 2 107 1 7 108(3S) (2S)≈ 1.2107 ,1.7108 (3S), (2S)

~ 5108 BB, DD, pairs≈ 1.2108 ,1.0108 (3S), (2S)

1B factories. Some selected topics 11

April 2008, BaBar shutdown June 2010, Belle shutdown


What happened since (selection) Improvement of the angle measurement 4% Measurement of from penguin dominated processes Surprise…B factories also measured quite precisely the other anglesp q p y g

~ 7o ~ 15o

Measurement of the direct CP violation in charmless decays I d t f |V | |V | (6 7%) 1 5% Improved measurement of |Vub|, |Vcb| (6-7%), 1.5%

(improved theory, moment analyses,…) First measurement of the leptonic decay B Measurement of BS oscillations mS (Tevatron) First measurement of the CP violation in the BS sector (Tevatron) Measurement of Br and CP asymmetries in radiative and dilepton decays Measurement of Br and CP asymmetries in radiative and dilepton decays Surprise…Strong evidence for D0-D0 oscillations. CP violation in charm? Observation of many new and unexpected states: b(1S), Ds0

*(2317), charmonium-like t t (X Y Z f ili )states (X, Y, Z families)

Largely improved limits on lepton flavor violation Direct searches for light new physics …

1B factories. Some selected topics 12B factoriesIMFP 2011, LSC

sin2 in b→ccs decays

=(21.1±0.9)o


The UT angle Access to from the interference of bu Tree decay () with B0-B0 mixing (2) Access to from the interference of bu Tree decay () with B B mixing (2)

complicated by Penguin contribution

B0B0 mixing Tree decay Penguin decay

()

d0B

*tbV

b0B

t

*tdV d

u0B

/ubV

*udV

b /u

du0B

/gb

/utcu ,,

dtdV bt

tbV** // tdtbtdtb VVVVpq

ddB /

ubudVVA *

dd /u

tbtdVVA *

2 2 2CP CP CP

i i if f f

q A e e ep A

22 | | eff

f CP CP CPCP

i iii

f f fi i

T Pe ee eT P e e

sin 2

0CP CP

CP

f f

f

S

C

21 sin 2

sinCP CP CP

CP

f f f eff

f

S C

C

How can we obtain

To extract from eff requires SU(2) isospin symmetry between u and d quarks (mu ~ md) which allows to relate A(B0h+h-) A(B0h0h0) and A(B+h+h0 ) + CP conj

from αeff ?T(P) = tree (penguin) amplitude = PT , strong phase difference

md), which allows to relate A(B h h ), A(B h h ) and A(B h h ), + CP conj.

F. Martínez‐Vidal 1B factories. Some selected topics 14

Gronau/London analysisGronau/London analysis


from B Measure 6 observables (for 6 parameters to be determined) from the 6 samples,

B0+-, B000 and B++0 , + their CP conjugates

S C C BF BF BF0 0 0 0 0, , , , ,S C C BF BF BF

Still, 1.9difference


from B Measure 7 observables (for 6 parameters to be determined) from the 6 samples,

B0+-, B000 and B++0 , + their CP conjugates

´S C S C BF BF BF f s0 0 0 0 0 0 0, , , , , , , LS C S C BF BF BF f s

B experimentally challengingo Up to 20 in final stateo is broado is broado VV final state

But more efficient than o BF’s ~5×times larger o Penguin pollution smaller than in o ~100% longitudinally polarized g y p

almost pure CP even state o All isospin modes have time

dependent information


dependent information


determination

4.44.289.0

(91.4 6.1)

Mainly determined by B isospin analysisMainly determined by B isospin analysis


The UT angle γ from B→DKB Measure interference between tree amplitudes b→u and b→c

**

0 D0

* Use final state accessible from both D0 and D0

Largely unaffected by New Physics

B

Clear theoretical interpretation of observables in terms of γ

Difficult because BFs are small due to CKM suppresion(10 5 10 7 t t ) d |A |/|A | i ll d t(10-5-10-7, so not many events) and rB=|Aub|/|Acb| is small due to further CKM and color suppressions (small interference)


γ from B→DK

“Golden”

Charged B→D(*)0K(*) Neutral B→D(*)0K*0

rB~0.1 rB~0.3B

GLW

K- K+

ADS

K0s π+ π-

Dalitz plotGolden

Dalitz plot

π0 π+ π-

K0 +

ADS

K+ π-f =

π+ π-

K0s π0

K0s ω

CP

-eve

n

K+π-K+π-π0

K+π-π+ π-

ADS

K0s K+ K-

K0s π+ π-

K+ π-π0

K+ π-π+ π-

* K0s Φ

CP

-odd

CP j CP jCP jCP j

*

f =CP-conj CP-conj

Complementary methods applied on same B decay

CP-conjCP-conj

*Complementary methods applied on same B decay

modes share the same hadronic parameters (rB, B) and

Strategy: many decay chains are analyzed and then B gy y y ycombined to improve the overall sensitivity to γ


“Golden” Dalitz plot methodγ from B→DKRe cos( ) Im sin( )

B Bub ub

B BB Bcb cb

A Ax r y rA A

Significance for direct CP violation is 3.5 for each experiment r

B

Fist strong evidence for direct CPV in charged B decaysBr

B

Br B

1514(68.4 4 3) 11

12(78 4 9)


determination

2125(71 )

(74 11)

Mainly determined by Dalitz plot analysis


Mainly determined by Dalitz plot analysis


Measuring the sides Semileptonic B decays give direct access to magnitudes

of the CKM matrix elements

Challenge is to understand hadronic current Inclusive: bq l + QCD corrections + OPE( /m ) also relevant for bs Inclusive: bq l + QCD corrections + OPE(S, /mb), also relevant for bs Exclusive: form factor(s) describing Bl hadron -- LQCD

Alternative: purely leptonic B decays (e.g. B )

Theory more straightforward, still LQCD for fB


Theory more straightforward, still LQCD for fB

Underconstrained events tagged (recoil) samples


Methodology: the recoil method

Knowledge of signal kinematics, missing energy and suppression of combinatorial background

B t l t ti ffi i But low reconstruction efficiency Used for inclusive measurements or for decays with multiple neutrinos Hadronic tags (e.g. BD), efficiency ~0.3% Semileptonic tags (e.g. BDl), efficiency ~0.6%


Inclusive |Vub|

Ch ll f B X l d i i d b k d f CKM f d B X l Challenge for BXu l determination due to background from CKM-favored BXc l decays

Kinematic selection required to suppress backgrounds, but cuts restrict phase space, hence OPE unapplicable unless one uses a shape function pp p

Introduces dependencies on non-perturbative shape functions to account for efficiency loss in inaccessible regions of phase space

Trade-off between extending measurements into higher background regions and g g g gincreased theory uncertainties on |Vub| extraction


Inclusive |Vub| Experiments use hadronic tag and select

high momentum leptons (pl*>1 GeV/c)

Further background suppressions using g pp gmultivariate techniques

Fit to other variables (MX, q2)

BaBar also performs partial branching fraction measurement in six regions of phasefraction measurement in six regions of phase space which have limited charm background

Partial branching fraction measurements translated into values of |V | using theoreticaltranslated into values of |Vub| using theoretical models (BLNP, GGOU, DGE, ADFR)


|Vub| from B(,)l |V | b d f f l i B l d B l diff i l |Vub| can be extracted from measurements of exclusive B l and B l differential

branching ratios

Theory input needed for form factor f+(q2) determination Branching fractions extracted from simultaneous fits to mES, E and q2

Extract shape of the B l form factor from differential branching fraction spectrum Extract shape of the B l form factor from differential branching fraction spectrum Alternatively |Vub| can be extracted from

a simultaneous fit data and lattice (FNAL/MILC)(FNAL/MILC)

2 2( )B q q2max2

2 2 3 2 2( ) | ( ) |q

FG f d min max2 2

0 min max

( , )| |( , )ub

B q qVq q

F. Martínez‐Vidal 1B factories. Some selected topics 26

2min

2 2 3 2 2min max 3( , ) | ( ) |

24F

q

q q p f q dq


|Vub| semileptonic summary

Significant improvements in techniques for |Vub| extraction in recent years, but long-g p q | ub| y , gstanding discrepancy between inclusive and exclusive determinations persists (~2.5)


|Vub| and B++ Theoretically clean determination of |V | from helicity suppressed leptonic modes Theoretically clean determination of |Vub| from helicity suppressed leptonic modes

B ubf V

Experimentally challenging due to small branching fractions and limited kinematic informationinformation Only accessible to B factories

Possible to use both hadronic and semileptonicreconstruction of tag B

E i ll ddi i l l f ki i i f i f Essentially no additional loss of kinematic information from use of BD(*)l tags


|Vub| and B++ Topological selection of decay candidates

in e, , and modes from particles not associated with the tag B candidateassociated with the tag B candidate

Signal B+ + events expected to have littl th ti it i th d t tlittle or no other activity in the detector, while backgrounds have higher multiplicity

Characterize additional activity by Eextra, summed energy of all remaining calorimeter activity

Validate Eextra shape using samples in which the 2nd B is exclusively reconstructedy

ICHEP 2010, ParisICHEP 2010, ParisICHEP 2010, Paris 1B factories. Some selected topics 29B factoriesIMFP 2011, LSC

|Vub| and B++Hadronic tag

Semileptonic tag0.57 40.54(1.80 0.26) 10 Hadronic

4(1.7 0.8 0.2) 10 0.56 0.46 40.49 0.51(1.79 ) 10

Semileptonic

Hadronic0.38 0.29 40.37 0.31(1.54 ) 10 Semileptonic

Average 4(1.68 0.31) 10 Larger than favored by by semileptonic |Vub|…

F. Martínez‐Vidal 1B factories. Some selected topics 30B factoriesIMFP 2011, LSC

|Vub| and B++ C i i h B i i i l i f Comparison with B mixing measurements permits cancelation of

parametric uncertainty from fB

2 22 2( ) 3 1 1 sin1Br B m m

…but odd correlation between B and sin2

2 2 2

( ) 14 ( ) | | sin

d

Bd W t B B udm m S x m B V

Tension with respect to indirect determination from sin2 at the level of 3 Not driven by the semileptonic value of |Vub| nor fB


Global SM fit2000today …2000…today

Coherent picture of FCNC and CPV processes in SM = 0.342 ± 0.016 (~4%)

= 0.144 ± 0.025 (~15%)

p

CKM matrix is the dominant source of flavour mixing and CP violation !1B factories. Some selected topics 32B factoriesIMFP 2011, LSC

Discrepancies persist between inclusive

Yes…but… Discrepancies persist between inclusive

and exclusive |Vub| determinations Precision on should be improved at

least 4 to have stringent test of SM

|Vub| and select - value independently of most

Recent (and internally consistent) B++ measurements favors larger |Vub|

types of NP SM candle type of measurement

Tension between direct and indirect determinations of sin2 and Br(B++ ) (~2.2 and ~2.8) Not driven by the semileptonic value y p

of |Vub| nor fB

Another way: to accommodate Bwe need larger |V | but to accommodatewe need larger |Vub|, but to accommodate sin2 we need lower |Vub|

Discrepancies in the CP asymmetry in BS sector (~3) should also be considered! Improvement in predictions and measurements are of the outmost importance

F. Martínez‐Vidal 1B factories. Some selected topics 33B factoriesIMFP 2011, LSC

Searching for New Physics New Physics at 10 GeV?

Virtual BSM contributions especially in loops! Virtual, BSM contributions…especially in loops! In general induces (additional) FCNC

Decay rates, CP asymmetries, angular distributions all can be affected by y , y , g yNP effects

The particle in the loop can be very heavy…sensitive measurements can probe NP at the multi TEV scaleprobe NP at the multi-TEV scale

…and also searches for directly produced low mass states Huge datasets collected by B-factories at all (nS) resonances allow to g y ( )

explore NP …Luminosity frontier Complementary to direct searches at energy frontier (Tevatron, LHC)


B++

i h h d i

B ubf V

With charged Higgs2

Discrepancy between SM fit and WA BR

4( ) (1.68 0.31) 10WAB B 0.114 40.061( ) (0.763 ) 10CKMB B

2.8

Conversely, we can set exclusion regions in m(H+) vs tan

4( ) (1 20 0 25) 10B B ( ) (1.20 0.25) 10SMB B

1 11B factories. Some selected topics 35

Using fB (HPQCD) and |Vub| (HFAG)B factoriesIMFP 2011, LSC

If single phase dominates SM predicts S=sin2 C=0

sin2eff from b→s penguins If single phase dominates, SM predicts S=sin2, C=0 Dominant CKM factors as in J/KS

W+

B0b

d

ʉ, c, ŧ

g(KK)ss

Sensitivity in the loop to New Physics effects

d sd

K0

g

sb b s

~

~ ~

After a long story of disagreement…Today there is a rather d t b t

LRd

23

good agreement between bqqs: sin2eff = 0.64 ± 0.04 (Naïve average) bccs: sin2= 0.672 ± 0.023 (0.028 with theo. error) …but lowside bias?


Radiative penguin decays bs

For E >1 6 GeV SM prediction to O( 2) is 4( ) (3 15 0 23) 10B B X For E>1.6 GeV, SM prediction to O(s2) is

BXs from sum of exclusive states Reconstruct Xs/d as K/ + up to 4 pions

( ) (3.15 0.23) 10SM sB B X Misiak et al., PRL 98, 02002 (2007)Misiak et al., PRL 98, 02002 (2007)

Must correct the observed rate by the fraction of decays not reconstructed……depends on fragmentation model

44

6

( ) (2.3 0.1 0.3) 10

( ) (9.2 2.0 2.3) 10for 2 0 GeV

s

d

B B X

B B XM

Can be used for independent determination of |Vtd|/|Vts|

for 2.0 GeVXM

td ts


Requires extrapolate up to full mass range…another (small) theory error. And DR from UT fit…


Inclusive BXs Error on inclusive measurement blows up at lower photon energy Balance between statistical errors and the error from extrapolating down to 1.6 GeV

(shape function, as in inclusive |Vub|)( p | ub|) Use recoil method or high p lepton to tag events… Bd background is subtracted out

4( ) (3.55 0.26) 10HFAG sB B X


Dilepton penguin decays bsl+l-

D 10 2 ll h b Decay rate 10-2 smaller than bs BUT, more observables sensitive to NP For example, exclusive BK*l+l-

K* longitudinal polarization Lepton FB asymmetry BR´s lepton flavor isospin asymmetry

Amplitudes and their NP effects can be expressed in terms of effective Wilson coefficients C7

eff , from the EW penguin

BR s, lepton flavor, isospin asymmetry,…

SM J/ (2S) C9 (V) and C10 (A),

from the interference of the Z penguin and

C7=‐C7SM

of the Z penguin and W+W- box diagrams


(Semi)Inclusive BXsl+l-

From sum of exclusive states Reconstruct Xs as K±/Ks + up to 4 pions

10

6( ) (3 66 0 77) 10B B X l l 2 2

( ) (3.66 0.77) 10

for >0.2 GeV/cHFAG sB B X l l

q

MC/D t diff NP?MC/Data differences f t ti d l MC/Data differences NP?fragmentation models


Many radiative and dilepton measurements !

BR’s

Also CP asymmetries Also CP asymmetries Expected to be almost zero in the SM Null test for new physics search All ibl i h All compatible with zero

Crucial to improve the precisionF. Martínez‐Vidal 1B factories. Some selected topics 41B factoriesIMFP 2011, LSC

New physics with charm Charm is an up type quark ! Charm is an up-type quark ! NP inducing FCNC process could reveal couplings substantially stronger for up-

type than for down-type quarks B “SM” b k d h ll f FCNC f k ( ll i l ) But “SM” background much smaller for FCNC of up-type quarks (smaller signals)

CP violation (and mixing?) is the way to explore new physics with charm

Short-distance contributions from mixing box Short-distance contributions from mixing box diagrams in the SM expected to be small b quark is CKM-suppressed d d k GIM d s and d quarks are GIM suppressed Contributes mainly to x=m/ NP would show up here, y=(1-2)/2

mostly unaffected Long-distance contributions expected to

dominate, still small effect,

Most SM predictions: x,y ~ 0.001‐0.01 and |x|<|y||x|>>|y| could be hint of NP

but hard to estimate precisely SM CP violation at 10-3 level NP could increase up to few % level


|x|>>|y| could be hint of NP NP could increase up to few % level


I 2007 30 f A P i d S B T i fi l d b i B f i

Evidence for charm mixing In 2007, 30 years after A. Pais and S.B. Treiman first speculated about it, B factories

reported the first evidence for D0-D0 mixing (quickly confirmed by CDF)

Text book example: Wrong sign (WS) K+p- final states from D0 decays from 2 sources: via double-Cabibbo-suppressed (DCS) decays or via mixing followed by Cabibbo-favored (CF) decays


Evidence for charm mixing Wrong sign D0 decay time distribution

using right sign (RS) decay time and resolution function

Mixing parameters

R ti f WS/RS t i Ratio of WS/RS events varies as a function of time due to mixing


Charm mixing and CPV Averages with CP violation allowed with all available measurements: mostly from B Averages with CP violation allowed with all available measurements: mostly from B

factories, but also CDF and CLEO-c (from about 30 “mixing” observables)

+2010

No

+No CPV

0.190 20(0.63 )%x 0.18

0 16| / | 0.91q p

MixingCPV

0.20( )%(0.75 0.12)%y

0.16

9.48.9

| |

( 10.2 )

q p

Evidence of D0 mixing exceeds 10 combining all experimental results,


but no single measurement exceeds yet 5 No evidence for CP violation (either in mixing, decay or interference)


Charm mixing and CPV Averages with CP violation allowed with all available measurements: mostly from BEPS 2009 before the new D0 K +‐+ K K +K ‐ Averages with CP violation allowed with all available measurements: mostly from B

factories, but also CDF and CLEO-c (from about 30 “mixing” observables)EPS 2009, before the new D Ks + KsK K results from BaBar, so far the most precise single and direct measurement of x and y

+2009

+No

No CPV

+

(0.98 0.25)%x | / | 0.87 0.16q p

MixingCPV

( )(0.83 0.16)%y

| |( 8.5 7.2)

q p

Evidence of D0 mixing exceeds 10 combining all experimental results,


but no single measurement exceeds yet 5 No evidence for CP violation (either in mixing, decay or interference)


(nS)+Exotic ! R. Dermisek et al., S. PRD 76, 051105 (2007)R. Dermisek et al., S. PRD 76, 051105 (2007)

A number of BSM models predict light weakly-interacting degrees of freedom

E g NMSSM models with light CP odd Higgs E.g. NMSSM models with light CP-odd Higgs CP-odd Higgs, A0, below 2mb, is not constrained

by LEP Large BR(A0) possible Search in the unprecedented (nS) samples@B factories

Also models with low-mass dark matter and/or gauge bosons motivated by -ray and positron emission from

l i (INTEGRAL PAMELA ATIC )galactic center (INTEGRAL, PAMELA, ATIC, etc.) E.g. “Dark Sector” DM particles in ~TeV range, but new gauge bosons p g g g

in ~GeV range New gauge bosons decay to lepton pairs, antiproton production forbidden by

kinematics or suppressed (explains PAMELA/ATIC features)kinematics or suppressed (explains PAMELA/ATIC features) Search for low-mass states in e+e- annihilation@B factories


(nS)+Exotic

A0+-

0 Searches performed in: (2S,3S)+-, (3S)+-

o Look for a peak in the m(l+l-) spectrum

A0+-

A0invisible

o Look for a peak in the m(l l ) spectrum

(2S) (1S) (1S) i i ibl (2S)+-(1S), (1S)+invisibleo Missing mass + dipion recoil masso Invisible is either a particle (e.g. A0),

or a pair of DM particles,

Well understood initial state

Well understood initial state Narrow (2S) or (3S) Fully or partially reconstructed final state,

depending on the decay pattern of A0

Look for e+e-l+l-l+l- final state (4e,2e+2,4) as Look for e e l l l l final state (4e,2e 2,4) as a function of two lepton mass


Light Higgs & DM limits (1S)+invisible

e+e-W’W’l+l-l+l- e+e W W l+l l+l


Conclusions and perspectives Great success of the B factories in the last decade

Many measurements in B, D, tau, quarkonium, t ith it f t d ltetc. with quite a few unexpected results

CKM mechanism confirmed CKM mechanism confirmed All measurements of quark mixing & CP violation consistent with CKM

Several possible hints (“tensions”) for effects of physics BSM (sin2, B, K*l+l-; ASL, S from Tevatron) The contrary would be suspicious……3 effects are 99.7% of the time wrong…but make life more interesting…3 effects are 99.7% of the time wrong…but make life more interesting Large contributions (~10%) from NP not excluded with current data sets

Despite the huge progress made by B factories, much remains to be done New and more precise measurements, better predictions

Enormous discovery potential for next generation experiments Enormous discovery potential for next generation experiments…


LHCb h t t ti l i b t t ll t

Next generation B factories LHCb has great potential in many –but not all- sectors

(Lluis Garrido’s talk yesterday)

Important examples only accessible in e+e- collisions B l , B K, and rare decays

Two next generation e+e- experiments proposed and approved, target is >75fb-1

BelleII pgrade of Belle appro ed in Japan BelleII – upgrade of Belle, approved in Japan, commissioning starts ~2014

SuperB – new approved in Italy, reusing BaBar/PEP-II hardware, commissioning starting ~2016

The two designs share much in common. Main differences: Potential for beam polarization at SuperB ( physics, LFV, etc.) Running at DD threshold in SuperB Running at DD threshold in SuperB

Will ensure progress in understanding flavor physics throughout the LHC era 1B factories. Some selected topics 50B factoriesIMFP 2011, LSC

Observable Babar/Belle

LHCb(10fb‐1)

SLHCb(100fb‐1)

SuperB(75ab‐1)

Some Comment Theo

No result Moderate Precise Very PreciseSome Golden Modes

Vub/Vcb Excl. needs Lattice & Inclusive @ 2% ?

Theo. error to be controlled on data (ex: J/0) THEORY

S(J At 1o theo error controlled with data ?

B Very precise if detector is improvedModerately

S‐Penguins SLHCb (very) precise for BK, BsNot possible for Ks0,ksksks,ks, Ks..

ACP(B Xs) Control syst. Is an issue

yClean

CleanBr (B Xs) Syst. Controlled with data ?

Br (B Xs l l)Angular var.

CleanNeed Lattice

Br(BK*l l ),Angular var.

Could theory control @20%? Angular analysis are clean ?

Br (B K(*) Stat. limited. With more stat. angular analyses also possible

Clean

Br (BKs)

Br(Bs) As precise as Br Ks) ?

Br (B)Br (Bs)

profit of polarized beams

CPV charm CPV in SM negligible. So clean NP probe 51

From A. Stocchi

B factoriesB factories - unizar.es · 2020. 9. 9. · CP violation in charm? Observation of many...

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