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Part I: 3-sigma anomaly of W->tau nu decay in new physics beyond SM ----first clean hint of right-handed charge current? (hep-ph/0504123). 朱守华( Shou-hua Zhu) Peking University July 2005 @ Tsinghua Univ. 3-sigma anomaly of W->tau nu measurements Anomaly in 2HDM and MSSM

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Part I: 3-sigma anomaly of W->tau nu decay in new physics beyond SM

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Part I:

3-sigma anomaly of W->tau nu decay

in new physics beyond SM

----first clean hint of right-handed charge current?


朱守华(Shou-hua Zhu)

Peking University

July 2005 @ Tsinghua Univ.

3-sigma anomaly of W->tau nu measurements

Anomaly in 2HDM and MSSM

Anomaly indicates right-handed charge current?

Two destinations of puzzles

1: Puzzles stand for new dynamics

  • Speed of light as constant

  • - puzzle

  • Sun neutrino missing

2: Puzzles stand for ignorance (both theoretical and expt.)

  • CDF di-jet

  • Re() in K-system

  • b-inclusive production

ADL final

O prel.

Anomaly mainly comes from L3

3-sigma anomaly of W->tau measurements, hep-ex/0412015

New physics?

3-sigma anomaly of W->tau nu is especially interesting and important:

In SM involved is only pure left-handed charge current

Simpler kinematics and less hadronic uncertainties.

Possible explanations in new physics beyond the SM:

Oblique-type corrections -> NO!

Flavor-dependent interaction!

Satisfy neutral-current data (Z-decay) at O(0.1%)

Satisfy tau-> nu_tau l nu_l data

Tan(beta) enhancement flavor interactions

Higgs-fermion Yukawa couplings in 2HDM

Chargino(Neutrolino)-fermion couplings in MSSM


2-Higgs doublet model (2HDM)

Negative except for near-degenerate Higgs mass case:

Lebedev etal., PRD62(2000)055014


Use FeynArts, FormCalc, LoopTools to scan parameter space

In most cases, delta_new is negative

In all cases

Anomaly in 2HDM and MSSM

  • It is hard to account for anomaly in two models.

  • And it is even harder to account for both W anomaly

    and neutral data.

Anomalous left- and right-handed couplings

From W->tau nu_tau data:

Constraints from tau-decay data

Delta_L and Delta_R are constrainted by Michel parameters which can be extracted from energy spectrum of daughter letopn in tau->nu_tau l nu_l.


Allowed small regions at 95% CL

dR: 0-> 0.12

dL: 1-> 1.005

Anomalous left- and right-handed couplings for

3rd generation quark :

From B->X_s gamma measurements:

Re(dR)< 4 10-3 for Wtb

F. Larios etal., PLB457 (1999)334

|dR| 0.12 for W


Summary for 1st part (questions)

Is W->tau nu_tau 3-sigma anomaly the first clean signal for the existence of right-handed charge current?

How is this anomaly related to fermion mass generation (flavor physics)?

Will parity be restored at high energy?

Does anomaly indicate the non-universality of gauge interactions for different generation? X.Y. Li and E. Ma, PRL47, 1788(1981)

Part II:Distinguishing Split from TeV (normal)SUSY at ILChep-ph/0407072, PLB604,207(2004)


Shou-hua Zhu

Peking University

July 2005@ Tsinghua Univ.


Why Split SUSY (SS)?

How to distinguish SS from TeV SUSY?

Chargino pair production at Linear colliders


Naturalness problem in the SM

mHphy= mH0 +c 2+…,  ---new physics scale

=> New Physics should appear at TeV

(TeV/ EW ~10)

Solutions (TeV scale New Physics) to Naturalness problem

TeV SUSY or little Higgs models

Low scale gravity

Composite Higgs boson etc.

Why Split SUSY? (I)

  • TeV New Physics is an attracting thing (important basis of future colliders), but …



S. Dawson, LP2005

  • TeV SUSY is a beautiful thing (GUT, dark matter, aesthetic …), but …

S. Dawson, LP2005

  • Shortcomings of TeV SUSY

    • not yet found Higgs  small hierarchy problem (remind: in MSSM at LO mH<MZ)

    • excess flavor and CP violation =>”CP problem”

    • fast dim-5 proton decay etc.

  • Seems MNew Physics >>TeV, did we miss something important? Is that possible that naturalness …?

Failure of Naturalness of Cosmological Constant ->…

Why Split SUSY? (II)



Fine tuning =>

  • God

  • mechanisms

Assuming UNKNOWN mechanism for finely tuned CC is also applied to Higgs sector…

  • GUT and Dark Matter instead of Naturalness are guiding principles  Split Supersymmetry

    N. Arkani-Hamed &S. Dimopoulos, hep-ph/0405159

  • Split Supersymmetry can get

    (a) GUT ( slightly improved)

    (b) Dark Matter density

    (c) higher Higgs mass (120~160 GeV)

    (d) cures to most of TeV SUSY diseases etc.



SS has only onefinely tuned and light Higgs boson while other scalars are ultra heavy.

Gaugino and Higgsino might be light.

Effective Lagrangian at low energy, besides kinetic terms, after integrating out higher scalar mass:

What is Split SUSY?

Precisely measuring Higgsino-gaugino-Higgs vertexes e.g. O(0.1 fb) hep-ph/0407108

Scale of scalars is the most characteristic feature of SS, but directly producing scalars other than light Higgs boson is difficult.

How to determine scalar mass?

(a) Long-lived gluino as a probe of scalar mass at LHC


How to distinguish SS?

(b) Chargino pair production at Linear colliders can probe the properties of chargino S.Y. Choi (1999) and (2000) and is sensitve to sneutrino mass.

Chargino production at LCs

SS Parameter Space & Mixed Region

  • Assuming gaugino mass unification and dark matter constraint:

    0.094 <DMh2<0.129

    G. Giudice & A. Romanino,


Point Pa: Differential  and Forward-backward Asymmetry


10 TeV

1 TeV

Point Pa: total 

(11), (12) and (22) are all sensitive to sneutrino mass up to 10 TeV for lower M2 and .

Point Pb: Total 

(22) Mode is most promising for higher

M2 and.

Chargino pair production can probe the sneutrino mass up to 10 TeV. Need further simulation!

It provides a very crucial method to distinguish Split from TeV (normal) SUSY.

All three modes (11), (12) and (22) should be analyzed.

Current and planning colliders can’t cover all SS parameter space.

Summary for 2nd part

Thanks for your attention!

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