parity symmetry at high energy how high n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Parity Symmetry at High-Energy: How High? PowerPoint Presentation
Download Presentation
Parity Symmetry at High-Energy: How High?

Loading in 2 Seconds...

play fullscreen
1 / 39

Parity Symmetry at High-Energy: How High? - PowerPoint PPT Presentation


  • 163 Views
  • Uploaded on

Parity Symmetry at High-Energy: How High?. Xiangdong Ji U of Maryland. In collaboration with Zhang Yue An Haipeng R.N. Mohapatra. Outline. Introduction A minimal left-right symmetric model Solving for the right-handed quark mixing K L -K S mixing K-decay  and neutron EDM

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Parity Symmetry at High-Energy: How High?' - avery


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
parity symmetry at high energy how high

Parity Symmetry at High-Energy: How High?

Xiangdong Ji

U of Maryland

In collaboration with

Zhang Yue

An Haipeng

R.N. Mohapatra

outline
Outline
  • Introduction
  • A minimal left-right symmetric model
  • Solving for the right-handed quark mixing
  • KL-KS mixing
  • K-decay  and neutron EDM
  • CP-violating in B-decay
  • Outlook

Parity symmetry at high-energy

parity symmetry and its breaking
Parity symmetry and its breaking
  • 50 years ago, Lee and Yang discovered that parity is not a sacred symmetry of nature, it is broken in weak interactions!
    • A fundamental discovery revolutionized the modern physics.
  • However, the origin of this parity asymmetry remains obscure till today.
    • Why God is left-handed?

Parity symmetry at high-energy

parity restoration at high energy
Parity restoration at high-energy?
  • Some believe that parity might be a good symmetry at a more fundamental theory. It is only broken at low-energy due to the structure of the vacuum that we live in
    • The dynamical equation is symmetric (in parity)
    • But the low-energy solution is not!
  • What are the signatures?
  • To what extent, they are model-independent?

Parity symmetry at high-energy

left right symmetric model lrsm
Left-right symmetric model (LRSM)
  • Based on gauge group SUL(2)XSUR(2)XUB-L(1) with parity symmetry at high-energy
  • New gauge bosons: WR & Z'
  • Explain the SM hypercharge
    • Q = I3L + I3R + (B – L)/2
  • Right-handed neutrino
    • R (massive neutrinos!)
  • Manifest and spontaneous CP violations

Parity symmetry at high-energy

a choice of the higgs sector
A choice of the Higgs sector
  • One left and right-handed triplet, L R, breaking the symmetry to the standard model
    • R = (0,0,vR) vR is at least TeV scale
  • One Higgs bi-doublet, , generating standard electroweak symmetry breaking
    •  is a CP violating phase
    •  and ' are electroweak scale vevs

Parity symmetry at high-energy

charged gauge bosons
Charged gauge bosons
  • The mass of the WL is close to the SM gauge boson (80 GeV)
  • The mass of the WR is unknown (exp bound > 800 GeV): MWR = gvR
  • They mix
    • The mixing angle depends on the vevs

W1 = WLcos + WRsin

tan  = '/vR2 = MWL2/MWR2 ,  = ’/

Parity symmetry at high-energy

quark currents
Quark currents
  • Both left and right-handed quark currents participate in weak interaction.
  • The left-handed quark mixing follows the standard model CKM matrix.
  • The right-handed coupling is a new unitary matrix in flavor space (quark mass eigenstates)
    • 6 CP violating phases
    • 3 rotational angles.
    • 25 = 32 discrete sectors

Parity symmetry at high-energy

quark mass matrices
Quark mass matrices
  • Quarks obtain masses through Yukawa coupling with Higgs bi-doublet
    • where h and h-tilde are hermitian matrices.
  • Mu and Md are general complex matrices and each must be diagonalized with two unitary matrices. Then right-handed quark mixing is independent of that of the left-handed quarks.

Parity symmetry at high-energy

special limits
Special limits
  • There are two sources of CP violations
    • Explicit CP violation in quark Yukawa coupling.
    • Spontaneous CP violation (SCPV) in Higgs vev.
  • When there is no SCPV, we have the limit of manifest left-right symmetry.
  • When there is no explicit CPV, we have pseudo-manifest left right symmetry.
  • In both cases the right-handed quark mixings are related to the CKM matrix.

Parity symmetry at high-energy

manifest left right symmetry
Manifest left-right symmetry
  • When =0, there is no SCPV, and the quark mass matrices are hermitian
  • Both can be diagonalized by single unitary matrices.
  • The right-handed quark mixing is the same as the CKM matrix, except for signs.

Parity symmetry at high-energy

pseudo manifest lr symmetry
Pseudo-manifest LR symmetry
  • All CP violation is generated by SCPV.
    • The CP phase in the CKM is also generated from the phase of the vev.
    • Very beautiful idea!
  • The quark mass matrices are now complex and symmetric, can be diagonalized by single unitary matrices
  • The right-handed quark mixing elements have the same modulus as these of the CKM matrix.

Parity symmetry at high-energy

a solution in general case
A solution in general case
  • Observation:
    • Because mt is much large mb, it is quite possible that there is a hierarchy between different vevs, ' barring a fine tuning.
  • If so Mu is nearly hermitian, and one can neglect the small h-tilde term.
  • Now the equation diagonlizing Md is

Parity symmetry at high-energy

equation for v r
Equation for VR
  • Using the hermiticity condition for h-tilde, one has,
    • Since it is a hermitian matrix eq., it has 9 independent equations, which are sufficient for solving for 9 parameters in VR
    • Let  = r mb/mt , the solution exists only for rsin <1

Parity symmetry at high-energy

the leading order solution
The leading-order solution
  • The solution

Parity symmetry at high-energy

cp phases
CP phases

Parity symmetry at high-energy

main features
Main features
  • The hierarchical structure of the mixing is similar to that of CKM.
  • Every element has a significant CP phase (first two families, order ; third family order 1), all related to the SCPV phase 
  • 32 discrete solutions are manifest.
  • From the above solution, one can construct the unknown h-tilde and solve Mu more accurately.

Parity symmetry at high-energy

k l k s mixing
KL-KS mixing
  • The mass difference between KL-KS due to weak interaction.
    • mK = 3.5 X 10–12 MeV
  • SM contribution
    • Long distance contribution,
      • hard to calculate exactly, order 50%, right sign
    • Short distance contribution
      • from intermediate charm quark. about 1/3 of the contribution, right sign.

Parity symmetry at high-energy

lrsm contribution
LRSM contribution
  • Large!
    • QCD correction, running from WR scale to 2 GeV, yielding a factor of ~ 1.4
    • Large logarithms ln(mWR2/mc2)
    • Large QCD matrix elements

~ (mK/ms+md)2 ms ~ 100 MeV

Parity symmetry at high-energy

the b factor
The B-factor
  • It was calculated by Wilson fermion formulation by UK QCD collaboration (Allton et al. PLB453,30)

B4 = 1.03

  • Recently it has also been calculated in domain-wall fermion formulation by Babich et al

B4 = 0.8 (hep-lat/0605016)

and CP-PACS (hep-lat/0610075)

B4 = 0.70

Parity symmetry at high-energy

constraint on m w r
Constraint on MWR
  • Because of the large hadronic matrix element, the bound on MWR is very strong.
  • The new contribution has an opposite sign.
  • The standard criteria is that the new contribution shall be less than the experimental value. This demands the SM contribution is 2Mexp
  • Using this criteria, one finds,

MWR > 2.5 TeV!

Parity symmetry at high-energy

comparison with previous bounds
Comparison with previous bounds
  • Smaller strange quark mass
  • QCD running effects
  • In the most general CP-violation scenario.

Parity symmetry at high-energy

is there a way to make the constraint relaxed
Is there a way to make the constraint relaxed?
  • Cancellation from the top quark contribution?
    • Top CKM is too small
  • Cancellation from the flavor-changing neutral Higgs contribution
    • They come with the same sign.
  • Smaller right-handed CKM?
    • Already fixed by the model, cannot be adjusted!

Parity symmetry at high-energy

indirect cp violating in k decay
: Indirect CP violating in K-decay
  • KL (predominantly CP-odd state) can decay into  state (CP-even)
  • The decay rate is proportional to =3x10–3
  • In SM,  arises from the box diagram with top-quark intermediate states.
  • In LRSM, WLWR box diagram provides the additional contribution.

Parity symmetry at high-energy

box contribution
Box contribution
  • Dirac phase contribution
    • Large contribution due to enhanced hadronic matrix element
  • New SCPV phase contribution
    • Comes from c-quark intermediate state.
  • Two contribution must cancel to generate reasonable size: this large fixes the parameter rsin

Parity symmetry at high-energy

fixing scpv phase
Fixing SCPV phase 

We have ignored large angle solutions

Parity symmetry at high-energy

neutron edm
Neutron EDM
  • Current best exp. bound

dn < 3.0 x 10–26 ecm

  • A new EDM exp. at LANL

dn < 6.0 x 10–29 ecm, improvement by 500

  • Standard Model prediction
    • Second-order weak effect (hadron level 10–7)
    • CP phase in s->d channel (10–4 )
    • dn ~ 10–32 ecm

Parity symmetry at high-energy

emd in lrsm
EMD in LRSM
  • First-order effect from
    • WL & WR mixing: W1 = WLsin + WRcos
    • Flavor-conserving, CP-odd weak current
  • Hadronic uncertainty
    • Single quark EDM
    • Hadron loop calculation

Parity symmetry at high-energy

bound on m w r from edm
Bound on MWR from EDM

Parity symmetry at high-energy

b decay constraint
B-decay constraint
  • In general, constraints from B-decay are less severe because the hadronic matrix elements involved have no chiral enhancement.
  • However, CP violation measurement in S(BJ/KS) is so accurate that it does not allow significant contribution from new physics.
  • SM phase

Parity symmetry at high-energy

ckm fit
CKM fit

Parity symmetry at high-energy

new contribution
New contribution

Parity symmetry at high-energy

constraint from s b j k s
Constraint from S(BJ/KS)
  • M>2.5 TeV

Parity symmetry at high-energy

outlook and conclusion
Outlook and conclusion
  • With the standard Higgs choice, the bound on MWR on is about 2.5 TeV.
  • Possible lower bound?
    • Add supersymmetry
    • Different Higgs structure
      • Two Higgs doublet
      • Hard to generate fermion mass
  • LHC? ILC?

Parity symmetry at high-energy

lhc ilc
LHC & ILC
  • At LHC, RH-W can be searched through 2 lepton+2 jet signals.

A year running -> bound 3.5 TeV

  • At ILC, impossible in direct production

Asymmetries through virtual production

Parity symmetry at high-energy