CP Highlights: Circa 2005
description
Transcript of CP Highlights: Circa 2005
CP Highlights: Circa 2005
Amarjit Soni
HET, BNL
………….
National Taiwan Univ.
6/23/05
Outline• Introduction: B-Factory + Lattice …help attain an imp. milestone ->
• Improved Searches for χBSM in the light of BF results:
Indirect Searches with theory input
Indirect Searches w/o theory input: Elements of a Pristine UT
Direct Searches:
Penguin dominated hadronic modes
Radiative B-decays
Null Tests
• K-UT
• NEDM
• TEDM
• Link with ν-Physics: Leptogenesis
• Summary
Atwood +Soni, CKMfit PLB’01
More sophisticated recent updates (CKMfitter,J.Charles et al ’04; Utfit M.Bona et al’05) with
similar numbers
Theory vs. Expt (’04)• Angle Theory Expt.
• Sin2β .70+-.10 .726+-.037
• α [98+-16]ο [103+-13]ο
• γ [60+-7]ο ~ [70+-30]ο
EXPT MEANS “DIRECT DETERMINATIONS”
- Most likely effect of any BSM-CP-odd phase on B-physics
is (from now on) a perturbation. …..A SIGNIFICANT CAVEAT
Important Lesson from the CKM-paradigm
• We know now that CKM-phase is O(1)• CP asymmetries in K-decays are at most (.001)• In charm decays CPV expected to be very small• In top physics asymmetries are completely
negligible• Only in B decays effects are O(1)• If there is BSM-CP-odd phase of O(1) it would be quite a coincidence if B’s are favored again
eta
Basic ADSMaximize direct CP by maximal interference:
CLA X DCBS ~ CLS X CBA
B-
K- D0
K- D0
CLA DCBS
CLSCBA K-{K + π -}
Vub/N[Vcb Vcd Vus]-1 ~ 0.7
QM amplitude for two interfering pathsξK is strong phase for B ->K D0; ξfi is for D0 -> fi
ξK fi = ξK + ξfi
For a given final state fi 3 unknowns: unmeasureable Br(B- ->K- D)=b(K); ξK
fi ; γ
Taming Direct CP
• #ofmodes D0(bar D0) #Obs #unknowns
• 1 2 3• 2 4 4• N 2N N+2
• 4 8 6• .• .• ad infintum• .
Some of the relevant (common)modes of D0 ,D0
Br CP 1) GLW: CPES (CBA/SCBS)
KS [π0,η,η’,ρ0,ω]; π+ π- …. Σ few% <~10%
2) GLS: CPNES (SCBS)
K* K, ρ + π- …. ~0.5% <~10%
3) ADS: CPNES(DCBS)
K+ (*) [π- , ρ - , a1 -….] O(10-3) O(1)
gamma from B->DK with 2-body D decays
δ & β from TDCP studies of B0->”K0” D0
[Atwood & AS, hep-ph/0206045, develop methods for model independent use of multi-body & inclusive modes]
• Related works: Gronau & London ’91; Branco, Lavoura & Silva, ’99; Kaiser & London ’01; Sanda’02;
Gronau,Grossman,Shumaher,Soffer and Zupan,hep-ph/0402055
I) Note δ=(β – α + π) = (2 β + γ); Note also that this is yet another (and even cleaner) method for β & of course also for γ. II) However, it is less efficient than either
B0 -> ψ KS or B+ ->”K+” D0
III) Asy: CPNES ~ 0.35 CPES ~ 0.75
Commonality of B+ , B0
Same decays of D0 are used in DIRCP in B+ decays as wellAs in TDCP in B0 ,allowing for info from charm factories &
And elsewhere to b recycled
Summary & outlook on (direct)γ
IV) With O(.4 ab-1 [NOW] ) γ ~ (69 +- 30)о
Attainable accuracy with O(2 ab-1 [`’08]) will
be appreciably faster than 1/sqrt(N) due to
the plethora of channels opening up
V) By ~ 2008, Expect δ γ ~ (2 to 5)ο
Vi)Ultimate precision O(.1%) that the theory offers will require SBF
I.Projections for direct determination of UT
• Now(.2/ab) 2/ab 10/ab ITE
Sin2φ1 .037 .015 .015(?) .001 α 13 4(?) 2(?) ~1(?)
γ(φ3) 20,10,10 5<->2 <1(? ) .05
Must strive for a pristine,direct determination ofAll 3 angles w/o theory assumptions to level of ITE.ITE should be the HOLY GRAIL-> SUPER-B is essential for this goal
DIRECT SEARCHES…illustrations
• Penguin dominated hadronic FS…
• Radiative B-decays
• Tests aglore
A tantalizing possibilty:
Signs of a BSM CP-odd phase in penguin dominated b ->s transitions?
Brief Recapitulation: Basic Idea
Dominant decay amp.has0 weak phase [just as in
B->ψKS] up to O(λ2)
J.Smith@CKM05
J. Smith@CKM05
WA ~ 2.7σ
Brief remarks on the old study(with London, PLB’97)
• Originally motivated by the thenCLEO discovery of• Huge inclusive (see Browder..) as well as exclusive• (see J. Smith…) Brs. into η’ • Suggest with Atwood(PLB97;PRL97) use of η’ Xs(d)
for search of NP via DIRCP as in SM expect very small• With London suggest use of MICP in [η’ ,
η ,π0,ρ0,ω,φ….]KS to test CKM-paradigm via sin2φ1(β)• Present simple (naïve) estimates of T/P …for all cases find, T/P <0.04• Due to obvious limitations of method suggest conservative
bound ΔSf <0.10 for the SM
For DIRCP see also Hou&Tseng,PRL’98
Glmpses from a few theoretical studies
• I. London &A.S.PLB’97…use naïve quark model to suggest
ΔS=0 + O(few%) for B->KS[ή,η,π,φ,ω,ρ…];but, in view of
hadronic uncertainties advocate ΔS>0.1 may be problematic
for the CKM-paradigm.Note, paper was basically motivated
by the huge Br of ή KS discovered @ CLEO
II 1) Mishima & Li (pQCD) KS[π,φ] very clean..[How about ή??]
• 2)Beneke&Neubert(hep-ph/0308039) use QCDF in
their study …main conclusion:
KS[ή,φ] are the cleanest modes with smallest ΔS & smallest
uncertainties
3)Cheng,Chua,A.S. [QCDF+FSI], KSή is cleanest; KSφ is
also very clean (hep-ph/0502235)
A possible complications: large FSI phases in 2-body B decays
• The original papers predicting ΔSf=Sf - SψK ~0used naïve factorization ideas; in particular FSIwere completely ignored.
A remarkable discovery of the past year is that directCP in charmless 2-body modes is very large->(LD)FS phases in B-decays need not be smallSINCE THESE ARE INHERENTLYNon-perturbative model dependence becomesunavoidable
4
723 10.3 6.5 2437
7.1 9.12 0.6 48
517 1.4 4.5 211
7.133.13
0
1.02.0
6.118.11
1415
0
1.99.9
0
B
B
KB
E x p t ( % ) Q C D F ( d e f a u l t ) Q C D F ( S 4 ) p Q C D
D C P V s i n s i n ( : w e a k p h a s e , : s t r o n g p h a s e )
Q C D F : Q C D f a c t o r i z a t i o n ( B e n e k e , B u c h a l l a , N e u b e r t , S a c h r a j d a1 9 9 9 )
p Q C D : b a s e d o n k T f a c t o r i z a t i o n t h e o r e m ( L i , K e u m , S a n d a )A s i z a b l e s t r o n g p h a s e f r o m p e n g u i n - i n d u c e d a n n i h i l a t i o n
Q C D F ( S 4 ) s c e n a r i o : l a r g e a n n i h i l a t i o n w i t h p h a s e c h o s e n s o t h a t a c o r r e c t s i g n o f A ( K + - ) i s p r o d u c e d ( A = 1 , A = - 5 5 f o r P P )
I t i s n a t u r a l t o c o n s i d e r L D s t r o n g p h a s e s i n d u c e d f r o m f i n a l - s t a t e i n t e r a c t i o n s
For penguin dominated modes,e.g (π,ω)KS
the subdominant tree is color suppressed, but FS rescattering phases arise from color
allowed tree so can have large effects
It is important
7
F S I a s r e s c a t t e r i n g o f i n t e r m e d i a t e t w o - b o d y s t a t e s
[ H Y C , C h u a , S o n i ]
F S I s v i a r e s o n a n c e s a r e a s s u m e d t o b e s u p p r e s s e d i n B d e c a y s d u e t o t h e l a c k o f r e s o n a n c e s a t e n e r g i e s c l o s e t o B m a s s .
F S I i s a s s u m e d t o b e d o m i n a t e d b y r e s c a t t e r i n g o f t w o - b o d y i n t e r m e d i a t e s t a t e s w i t h o n e p a r t i c l e e x c h a n g e i n t - c h a n n e l . I t s a b s o r p t i v e p a r t i s c o m p u t e d v i a o p t i c a l t h e o r e m :
i
ifTiBMfBMm )()( 2
• S t r o n g c o u p l i n g i s f i x e d o n s h e l l . F o r i n t e r m e d i a t e h e a v y m e s o n s ,
a p p l y H Q E T + C h P T ( f o r s o f t G o l d s t o n e b o s o n )
• F o r m f a c t o r o r c u t o f f m u s t b e i n t r o d u c e d a s e x c h a n g e d p a r t i c l e i s
o f f - s h e l l a n d f i n a l s t a t e s a r e h a r d
A l t e r n a t i v e : R e g g e t r a j e c t o r y [ N a r d u l l i , P h a m ] [ F a l k e t a l . ] [ D u e t a l . ] …
Cheng,Chua,A.S.Hep-ph/0502235
1.Note in SD, ΔS switches sign bet. ω,ρ for us no change2. LD rescattering effects on S & C are highly correlated and similarlyC’s of isospin partners are correlated -> many testable predictions,e.g
LARGE (13%)DIR CP for ω KS & HUGE for ρ KS (~ -46%)
ΔSf >0.10 would be a compelling evidence for BSM-CP odd phase!
Effects of FSI on penguin dominated modes(Cheng,Chua and AS)
Expectations for ΔS in the SMMode pQCD(SM ) QCDF(MB) QCDF+FSI(CCS)
η’KS .01(.01,-.01) .00(.00,-.04)
φKS ..020(.004,-.008) .02(.01,-.01) .03(.01,-.04)
πKS .009(.001,-.003) .07(.05,-.04) .04(.02,-.03)
HWT: η’Ks in pQCD?
J.Smith@SBF’05
Will answer thisLater in own way
C later
Averaging issue:Are we makinga mountain outa anthill?
• I am rather sceptical and concerned about
averaging over many small deviations,
leading to ~3.7 σ ….On the other hand,
London&A.S,hep-ph/9704277
Although, at the moment it is at best a marginal effect, it may well become a serious blunder on the part
of experimentalists to ignore it!We can try learn some lessons from history.
It is extremely important to understandthat basically it is a very good test of the SM and
theoretically it can be further improved
Christenson,Hicks,Lederman,Limon,Pope & ZavattiniPRD 8,2016 ‘72
<-`Leon’s shoulder
A p r i l 2 0 , 2 0 0 5 S u p e r B A B A R S t a t u s & P l a n s 3 1
0 . 0 0
0 . 0 2
0 . 0 4
0 . 0 6
0 . 0 8
0 . 1 0
0 . 1 2
0 . 1 4
0 . 1 6
0 . 1 8
0 . 2 0
Jan-
03
Jan-
04
Jan-
05
Jan-
06
Jan-
07
Jan-
08
Jan-
09
Jan-
10
Jan-
11
Jan-
12
Jan-
13
Jan-
14
Jan-
15
Jan-
16
Err
or
on s
ine
ampl
itu
de
P r o j e c t i o n s f o r S u p e r B F a c t o r y
f 0 K S
K S 0
K S
’ K S
K K K S
K *
5 d i s c o v e r y r e g i o n i f n o n - S M p h y s i c s i s e ff e c t o f 0 . 1 5
S u p e r B F a c t o r y 5 - 7 x 1 0 3 5 c m - 2 s - 1
P r o j e c t i o n s a r e s t a t i s t i c a l e r r o r s o n l y ; b u t s y s t e m a t i c e r r o r s a t f e w p e r c e n t l e v e l
L u m i n o s i t y e x p e c t a t i o n s
:
2 0 1 22 0 0 4
( ) 0 . 1 5S
S c a l e c h a n g e !
Macfarlane@SBF’05
M. Hazumi@CKM05
Can our theoretical understanding be improved?
YES!
• Improved measurements of Br and CP
[DIRECT AND MIXING INDUCED]
in related modes, such as [ή,φ,π…]K-(*)
can help greatly in improving model calculations
[EVEN THEORISTS CAN LEARN!]
What if improved measurements(e.g.) show ΔSήK>.20+-0.02
BOTTOMLINE
It is IMPOSSIBLE that genuine NP will show
up only in ή KS , many other hadronic (b ->s)
final states MUST show NP effects.
Furthermore, radiative and (pair)leptonic will in all likelihood be affected as well
B→γP1P2
• In this case there is potentially additional information from the angular distribution of the two mesons.
• There are two different cases of how the angular information enters
1) P1=P2 e.g. B0→π+π−γ. In this case the angular distribution gives you the information to calculate sin(2ψ) and sin(φL+φR+φM) separately.
2) P1 and P2 are C eigenstates e.g. B0→K sπ0γ. In this case you
can obtain no additional informaton from angular distributions but you can add all the statistics (as unlike AGS K pi need not be resonant) and thereby it allows a more stringent test for NP, that is, a more accurate value of the NP phase
• In both cases the variation with Eγ tests whether dipole
emission is an accurate model (see eq)
AG’HS (hep-ph/0410036)
Intutive elaboration of why/howAGHS idea works
In AGS eq.3, strong interaction (meaning leaving out weak phase) info is in (A sin ψ).For 3-body modes of AGHS interest, such quantities, in general,
become functions of Dalitz variables, s1 and cosΘ=z:
S1 = (p1 + p2)2 ; S2 = (p1 + k)2 ; S3 = (p2 + k)2
k is photon momentum, so z = ( S2 – S3)/ ( S2 +S3) .
Now for L,R helicities particle and antiparticle decays
we have 4 amplitudes so we have 4 such quantities now: fL , fR and similar 2 for anti-particle. Each is now a function of
s1 and z. But QCD respects P, C and therefore for ( I) the
case of Ks π0 all 4 become identically the same upto a sign.Thus time-dependent CP asymmetry A(t) becomes independent of Dalitz variables.
Expression for A(t) holds whether Ks π0 are resonant or not or from more than one resonance, in fact! Since A(t) is independent of s1 all points in Dalitz plot can be added. Significant improvement in statistics and in implementation. Combining the data together one gets significantly improved info on sin(ψ) sin(Φ) …the product of strong and weak phase which allows putting lower bound on each.
AGHS for π+ π- + gammaThis is the generalization for b -> d penguin of the rho gamma case…Since pi+ pi- are now antiparicles . Therefore, under C, S2 and S3 get interchanged and as a result z->-z.So angular distribution becomes non-trivial.Once again, resonant and non-resonant info can be combined but now additional angular info becomes available to allow a separate determination of the strong and the weak phase (up to dis. Ambig)!
Some Details• Usual Expt. Cuts to ensure underlying 2 body bs(d) + γ
is necessary…that is, HARD PHOTON…in particular to discriminate against Brehmms
• Departure from that will show up as smears around a central value on the Dalitz plot
• In principle, annhilation graph is a dangerous contamination, due to enhanced emission of (LD) photons off of light (initial) quark leg (see Atwood,Blok and A.S). This is relevant only to b ->d case. Fortunately,can prove that these photons have have same helicity as from the penguin. See AGHS for details.
Implications for B -> K ή γ of AGH’S
• AGH’S not only allows K π γ from allKaonic resonances (irrespective of JCP) as well as from non-
resonant continuum to be included even a more important repercussion
off AGH’S is that K ή γ can be used. This is significant as Br(K ή)/Br(K π) ~ 7For these reasons expect AG’HS to allow improvement over
AGS (resonance only) by factor O(2-5) so that with current O(108.5) luminosities
asymmetries O(0.20) may become accessible. With 1010 B’s may be able to get down to O(few%)
Dealing with Theoretical subtelties• QCD corrections introduce complications (though don’t expect 0.1)….Asy(S) becomes function of inv.
mass,angle,final state, whereas all 3 collapse into a single constant for LO analysis; schematically:• dSi/dMdZ = A0 + Bi +Ci M+ DiZ
where I=γ[K*, K,2*,K3*….;K π(η’,η)…]• That is now HW for the exptalists …do MC• Important point is that INTERPERTATION IS DATA DRIVEN
It would be useful to theoretically compute the coeff. For exclusive FS.
• These are radiative NOT hadronic final states.• Therefore calculations significantly less difficult than exclusive• Hadonic FS• Should be amenable to pQCD, QCDF, SCET….
Hierarchy of CP asymmetries in radiative B-decays
MIXCP DIRCP
b->s O(λ2) ~ 3% 0.6%
b->d O(.1%) O(15%)
April 20, 2005 Super BABAR Status & Plans 34
0.00E+00
1.00E+03
2.00E+03
3.00E+03
4.00E+03
5.00E+03
6.00E+03
7.00E+03
8.00E+03
9.00E+03
1.00E+04
Ja
n-0
3
Jul
-03
Ja
n-0
4
Jul-
04
Ja
n-0
5
Ju
l-05
Jan
-06
Ju
l-06
Jan
-07
Ju
l-07
Ja
n-0
8
Jul
-08
Ja
n-0
9
Jul-
09
Ja
n-1
0
Ju
l-10
Jan
-11
Ju
l-11
Jan
-12
Jul
-12
Ja
n-1
3
Jul
-13
Ja
n-1
4
Jul-
14
Jan
-15
Ju
l-15
Jan
-16
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19
0.20
Projections for K*Eff
ecti
ve n
umber
of
tagg
ed e
vent
s
Err
or o
n si
ne a
mpl
itud
e
PEP- I I , KEKB Super B- Factory 10/2011
SuperB
MacFarlane@SBF’05
Browder&A.S,hep-ph/0410192
Approximate Null Tests (Ants)Aglore
Direct Searches
K-Unitarity Triangle
• There is considerable interest in constructing the• UT purely from K-decays…relevant reactions being• pursued:
• Indirect CP violation parameter ε with BK from lattice
• K+ ->π+ υ υ can give clean Vtd
• KL ->π0 υ υ can give super-clean η (expt. very challenging)
• Direct CP ε’ with lattice matrix elements (theo. Very• Challenging)
Neutron EDM: a classic “null” test• In the SM NEDM cannot arise at least to two• loops in EW……..expect < 10-31 ecm• Long series of experiments now place• a 90% CL bound, <6.3 X 10-26 ecm (Harris et
• al, ’99)• In numerous BSM, including SUSY, Warped• extra-dimensions, …… neutron edm close• to current bound is expected
Top quark EDM: a clean “null” test
• Top is so heavy compared to other quarks that
GIM mechanism is super-effective -> all SM
CP violation effects are vanishingly small.
• As one concrete illustration is the top quark
Electric dipole moment….In the SM you need to
go to 2 loops in EW
Expectations for top quark edm in SM & Beyond
Atwood, Bar-Shalom,Eilam & Soni, Physics Reports:CP Violation in top quark physics
Search for BSM CP violation in top physics is an importantgoal of the International Linear Collider
Summary (1 of 2)
• Spectacular success of B-factories -> milestone in our understanding of CP violation: CKM-paradigm is confirmed. • Direct measurements of β agree remarkably with theoretical expectations to about 10% ; so also the 1st relatively crude measurements of α and γ ->any beyond SM CP-odd phase likely to cause a small perturbation in B-physics…..Likely to require lots and lots of clean B-samples and super clean
predictions from theory to search BSM phase
Summary (2)• In particular, we know now how to determine γ and α also (β was already known) to accuracy of better than O(1%)….this will require 1010 B’s, some 20 times more than current luminosities but is extremely well motivated• Penguin dominated hadron FS, much in the news but for now no convincing “deviation” from SM; However, it is a powerful test and its extremely important to reduce errors to O(5%) …may well need a SBF• K-UT, NEDM, TEDM…need be pursued with renewed
vigor in search for new sources of CP-odd phase(s)