Hints for new physics in flavour decays. Tsukuba. March 2009

S.Monteil Global Fits - CKMfitter Group 1

Hints for new physics in flavour decays. Tsukuba. March 2009

CKM Fits : Standard Model and New Physics

Stéphane Monteil, LPC, Université Blaise Pascal - in2p3/cnrs

On behalf of the CKMfitter group. http://ckmfitter.in2p3.fr

J. Charles, Theory, CPT MarseilleO. Deschamps, LHCb, LPC Clermont-FerrandS. Descotes-Genon, Theory, LPT OrsayR. Itoh, Belle, KEK TsukubaA. Jantsch, ATLAS, MPI MunichH. Lacker, ATLAS & BABAR, Humboldt U. Berlin

A. Menzel, ATLAS, Humboldt U. Berlin S. Monteil, LHCb, LPC Clermont-FerrandV. Niess , LHCb, LPC Clermont-FerrandJ. Ocariz, BABAR, LPNHE ParisS. T’Jampens, LHCb, LAPP, Annecy-le-VieuxV. Tisserand, BABAR, LAPP, Annecy-le-Vieux K. Trabelsi, Belle, KEK Tsukuba


Hints for new physics in flavour decays. Tsukuba. March 2009

Outline1. Introduction

2. The SM CKM Global Fit (experimental inputs, theoretical inputs, numerical results).

3. Model-Independent analysis of NP in F=2 transitions

4. Test of a specific NP scenario: 2HDM (Type II).

5. Conclusions


1) CKM Matrix: The Four Parameters

⎟⎟⎟

⎠

⎞

⎜⎜⎜

⎝

⎛=

tbtstd

cbcscd

ubusud

VVV

VVV

VVV

VCKM

Consider the Wolfenstein parametrization as in EPJ C41:1-131,2005 : unitary-exact and phase convention independent:

*

*

22

2

4222

2

2 and,cbcd

ubud

usud

cb

usud

us

VV

VVi

VV

VA

VV

V−=+

+=

+= ηρλλ

λ is measured from |Vud| and |Vus| in superallowed beta decays and semileptonic kaon decays, resp. A is further determined from |Vcb|, measured from semileptonic charmed B decays.The last two parameters are to be determined from angles and sides measurements of the CKM unitarity triangle.

http://www.springerlink.com/index/10.1140/epjc/s2005-02169-1


1) CKM Matrix: The Four Parameters

These four parameters are measured within a global frequentist analysis of the set of relevant observables on which we think to have a good theoretical control. In one table, the observables and the key ingredients:

Phys.param. Exp. observable Theory method/ingredients

|Vud| Superallowed decays Towner & Hardy, PRC 77, 025501 (2008)

|Vus| Kl3 (WA Flavianet) f+K(0)=0.964(5) (most precise: RBC-UKQCD)

|Vcb| HFAG incl.+excl. BXcl 40.59(38)(58) x10-3

|Vub| HFAG incl.+excl. BXdl (specif. uncer. budget): 3.87(9)(46)x10-3

md last HFAG WA Bd-Bd mixing BBs/BBd+ fBs/fBd + fBs + BBs

ms CDF Bs-Bs mixing BBs + fBs + fBd

B++ last 08 WA: BaBar/Belle fBs/fBd& fBs

|K| K°-K° (PDG08: KLOE, NA48,KTeV)

PDG param. (Buchalla et al. ‘96) + BK= 0.721(5)(40)

/1 latest WA HFAG charmonium -

/2 last WA ρρρ isospin SU(2) (GL )

/3 latest WA HFAG B-D(*)K(*)- GLW/ADS/GGSZ


2) CKM Matrix: The Standard Model Fit.

2.1) Theoretical inputs: lattice parameters

As underlined in the previous template, several QCD parameters are needed to perform the CKM fit and their knowldege critically impacts the overall precision. Many determinations of these paramaters from lattice QCD with different assumptions and treatment of the errors exist in the literature.

We are facing the question : what to choose ? more and more insistingly. And decided by default to go for our own average, from the set of unquenched results with 2 or 2+1 dynamical fermions.

Alternatives can be found in the literature (see for instance a recent work by Lubicz and Tarantino. We were used to take CKM06 -Tantalo). The single virtue of our approach is that it is algorithmic and hence reproducible. Note : The concept of theoretical error is ill-defined. Hence, what to say about their combination ?




Method of averaging:

Consider uniquely the statistical uncertainties in the average.

Rfit is taken for the other sources of errors, by the way added linearly for each measurement (when the splitting of the errors is known).

Assign to the average the smallest of the Rfit uncertainty (in order not penalize the best estimate).

Decay constants and bag factors:Example of the Ds decay constant: fDs




Details in http://ckmfitter.in2p3.fr



2.2) Experimental inputs: Winter09 updates.

sin 2 update (latest HFAG average)

Significant improvement for the measurement:

BaBar published a new measurement of the branching fraction B(B+ ρ+ρ0) (along w/ increased longitudinal polarization), which strongly constrains the isospin triangles and hence the alpha extraction.



2.2) Experimental inputs: the measurement.

B ρρ is now the most powerful contribution to the measurement (see Karim’s talk for details).



2.2) Experimental inputs: the alpha measurement.

It is the first time alpha contributes significantly to the metrology of the CKM parameters.



2.3) The overall picture

overall consistency at 95% CL.

CKM mechanism is at work for describing quark flavor transitions.

KM phase likely to be dominant in B’s.



2.3) Testing the KM mechanism:

CP-Violating observables stress the same feature

CP-Conserving observables imply CP violation.

Angles (small theoretical uncertainties) No angles (theoretical uncertainties dominate)


2) CKM Matrix: The SM Fit inside 95%CL. Tensions, frémissements, hints ?

2.4.1 |Vub| vs sin2 ?

It is actually more a |Vub| vs |Vub| tension. We are living with a significant difference between exclusive and inclusive measurements: a longstanding issue. The sin2 measurement prefers the exclusive value.


2) CKM Matrix: The Standard Model Fit. Tensions, frémissements, hints ?

2.4.2 |K| vs sin2? Buras & Guadagnoli recently advocated necessity of an additional parameter

in the SM lowering the prediction. The resulting tension |K| vs sin2 might have very appealing explanations (Soni & Lunghi).

We included the multiplicative additional parameter and got the result in green.

The tension arises if all the uncertainties on QCD parameters are Gaussian.


2) CKM Matrix: The Standard Model Fit. Tensions, frémissements, hints ?

2.4.3 BR(B++) vs sin 2?

Actually a large effect:

Tension between sin(2)() & BR(B++) () (through |Vub|):

Removing / in the CKM global fit, the 2min drops by 2.3/2.4 .



2.4.3 BR(B++) vs sin 2?

Looking in the detail, it is a non trivial correlation; we could think of |Vub|, |

K| , fBd…Actually, analysing simultaneouly md and BR(B++) gives a theory-free determination of the BBd factor and the tension is brought there.

Experimental fluctuation ?

LQCD input?

NP ? in mixing ?


3) New Physics in F = 2 transitions.

Aim at investigating in a model-independent manner the space left to NP contributions by the current data. Only two additional parameters added. Several equivalent parametrisations exist:

Hypotheses:

only the short distance part of the mixing processes might receive NP contributions.

Unitary 3X3 CKM matrix.

tree-level processes are not affected by NP (so-called SM4FC: bqiqjqk (ijk)). As a consequence, the quantities which do not receive NP contributions in that scenario are:



We are using in the following the cartesian coordinates parametrisation, following Nierste & Lenz (JHEP0706:072,2007)

The predictions of the observables sensitive to NP contributions are modified as:



The real and imaginary parts are mostly constrained by md (circle), sin2 (arcs) and .

Additional information is brought by the semileptonic asymmetries ASL and (hidden in that plot for the sake of clarity).



No evidence of NP but a departure from the SM at the level of 2 .

Mostly driven by BR(B++):

Within our hypotheses, we shall conclude that a NP phase can accomodate the large value of BR(B++).

Sizeable NP contributions in Bd system are still allowed.

hypothesis w/ B++ w/o B++

d= 1(Re=1,Im=0) 2.1 0.6



The Bs system:

The SM weak phase in the Bs mixing is very well predicted:



Dominant constraints:

ms agrees with SM.

(s=-2s,s) through time

dependent angular analysis of Bs J/ by D/CDF (HFAG’08 update) is 2.2away from SM.

The departure from SM value is 1.9. The main message is that the additional information (semileptonic asymmetries and lifetime difference) with the current experimental precision only marginally play. The s measurement is almost uniquely defining the discrepancy. A global fitter cannot say much there.

Eagerly awaiting the Tevatron update. With the expected LHC luminosity in 2009-2010, LHCb is at the corner.



Intermediate Conclusions

1. The CKM mechanism faced a great success in describing flavor dynamics of many constraints from vastly different scales. It’s the dominant source of CP violation in B system. The BaBar and Belle experiments provided fantastic measurements in that respect.

2. Stringent constraints on NP, established in a model-independent manner in F=2 transitions , are already existing in the Bd system. The Tevatron measurements in the Bs sector start to significantly constraint NP in the Bs sector.

3. We have not entered the precision era yet. A precise measurement is missing.

4. Most prominent deviations from SM : BR(B++) vs sin 2and s value.


4) Test of a Specific Model : 2HDM(II)

Motivation: it is a simple and predictive extension of the Standard Model. Same structure for the quark sector but new flavour changing charged interactions mediated by a charged Higgs.

Track charged Higgs contributions into tree or loop decays. Redifinition of the SM expression through corrections implying only 2 additionnal parameters:

2HDM is embedded into supersymmetric models (MSSM).

Charged Higgs transition is something we immediately imagine for BR(B++). Note: There are of course neutral higgses in 2HDM, which do not enter the processes under

consideration in this study.



All inputs are potentially subjected to receive charged Higgs contributions.

Yet, we neglected charged Higgs contribution for the following inputs, hence used to determine the apex of the unitarity triangle. Driven by (m_light/m_heavy)2 couplings |Vud|, |Vub|, |Vcb| and ().

We consider several observables subjected to receive Higgs contributions:

Leptonic decays

Semileptonic decays

The partial width of Z to bb (used to be a hint of NP!)

b s

Note: we did not consider in the present study the observables related to mixing, neither

Bs nor b sll.



The deviations w.r.t the SM predictions for the observables of interest. The orange band stands for two standard deviations. The experimental uncertainty is given at one standard deviation.



Leptonic decays:

Where M denotes any meson. [The radiative corrections are only relevant for light hadron decays].

The branching fraction is modified in the presence of Higgs contribution as :

Two solutions to find back to SM prediction: rH = 0. Generally send the H mass to infinity. rH =-2. Fine-tuned solution different for each meson.


4) Test of a Specific Model : 2HDM(II) / leptonic decays individual results


4) Test of a Specific Model : 2HDM(II) / leptonic decays individual results

Most of the indvidual fined-tuned solutions are removed at 95% CL

Large tan are excluded at small Higgs masses.


4) Test of a Specific Model : 2HDM(II) / semi-leptonic decays individual results

Semileptonic decays help further to remove indvidual fined-tuned solutions at 95% CL.


4) Test of a Specific Model : 2HDM(II) / b s

Calculated at NNLO (Misiak et al., 2006)

The normalized branching fraction (in notation from Gambino et al.) reads as:

For practical reasons, we’ve chosen to parametrize the P and N according to

Where A and B are two functions depending on a reduced set of relevant parameters (mb, mt, mc (btw, the most critical input)).They are fitted to reproduce the results from the open package SusyBSG (degrassi et al.)

Obviously a relevant laboratory for New Physics. Vastly investigated in the literature. A.J. Buras, M.Misiak, M.Munz, S. Pokorski, Nucl Phys. B424K. Chetyrkin, M. Misiak, M. Munz, Phys. Lett. B400. P. Gambino, M.Misiak Nucl., Phys. B611. M.Misiak, M. Steinhauser Nucl. Phys. B764.C. Degrassi, P. Gambino, P. Slavich, CERN/2007-265T. Besmer, C. Greub, T. Hurth, Nucl. Phys. B 609.


4) Test of a Specific Model : 2HDM(II) / the combined constraint

Leptonic decays (mainly BR(B++) ) constrain the parameter space at large tan. Rb constrains at small tan. We are ending with a unidimensionnal constraint on the charged Higgs mass mostly brought by b s.

2HDM(II) does not perform better than the SM.


4) Test of a Specific Model : 2HDM(II) / the combined constraint

No constraint on tan at 95 %CL.


5) Conclusion

overall consistency at 95% CL.

KM mechanism is at work.

Hints for new physics in flavour decays. Tsukuba. March 2009

Documents

Transcript of Hints for new physics in flavour decays. Tsukuba. March 2009