Kher Sham Lim, Max-Planck-Institut für Kernphysik Aspects of Classical Scale Invariance and Electroweak Symmetry Breaking ITP Teilchen-Tee, November 2014 Aspects of Classical Scale Invariance and Electroweak Symmetry Breaking Kher Sham Lim Max-Planck-Institut für Kernphysik ITP Teilchen-Tee Heidelberg 27.11.2014 Based on hep-ph/1310.4423, JHEP 1312 (2013) 076 by M. Holthausen, J. Kubo, KSL and M. Lindner Hep-ph/1403.4262, PRL 113 (2014) 091604 by J.Kubo, KSL and M.Lindner Hep-ph/1405.1052, JHEP 1409 (2014) 016 by J.Kubo, KSL, M.Lindner
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Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Aspects of Classical Scale Invariance and Electroweak Symmetry Breaking
Kher Sham LimMax-Planck-Institut für Kernphysik
ITP Teilchen-Tee
Heidelberg27.11.2014
Based on hep-ph/1310.4423, JHEP 1312 (2013) 076 by M. Holthausen, J. Kubo, KSL and M. Lindner Hep-ph/1403.4262, PRL 113 (2014) 091604 by J.Kubo, KSL and M.Lindner
Hep-ph/1405.1052, JHEP 1409 (2014) 016 by J.Kubo, KSL, M.Lindner
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
We know Higgs boson exist!
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
There!
Holthausen, KSL, Lindner '12Degrassi et al. '12Buttazzo et al. '13Bezrukov et al. '12Lindner' 86
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
New scale? New scale?
New scale?
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
New scale? New scale?
New scale?
ORIGIN OF ELECTROWEAK SCALE?
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
ORIGIN OF ELECTROWEAK SCALE?Dark matter
Strong CP problem
Neutrino mass
Dark energyBSM?
BaryogenesisInflation
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
ORIGIN OF ELECTROWEAK SCALE?Dark matter
Strong CP problem
Neutrino mass
Dark energyBSM?
BaryogenesisInflation
QCD scale is pure quantum phenomena
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
ORIGIN OF ELECTROWEAK SCALE?Dark matter
Strong CP problem
Neutrino mass
Dark energyBSM?
BaryogenesisInflation
QCD scale is pure quantum phenomenaDimension Transmutation
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
ORIGIN OF ELECTROWEAK SCALE?Dark matter
Strong CP problem
Neutrino mass
Dark energyBSM?
BaryogenesisInflation
QCD scale is pure quantum phenomenaDimension Transmutation
Put in by hand?
The only dimensionful parameter in SM
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
THE HIERARCHY PROBLEM
Supersymmetry?
Compositeness?
Extra Dimension?
➔ Ad hoc cancellation?➔ Boundary condition?
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
SUSY/ED/TC
Solutions getting pushed into special corner!
Long-held belief on naturalness must be critically reexamined!
But where are the new physics?
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
GENERATING ELECTROWEAK SCALE
Small in the SM as
Classical Scale Invariance!
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
GENERATING ELECTROWEAK SCALE
Small in the SM as
Classical Scale Invariance!
Might create a large hierarchy if new physics is still in the framework of QFT with large scale seperation. But Wilsonian picture might not apply to Planck scale physics!
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
GENERATING ELECTROWEAK SCALE DYNAMICALLY
Impose Classical scale Invariance
Want to generate EW scale dynamically
Order TeV to avoid Hierarchy problem
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
GENERATING ELECTROWEAK SCALE DYNAMICALLY
Impose Classical scale Invariance
Want to generate EW scale dynamically
Order TeV to avoid Hierarchy problem
Minor detail: Imposing classical scale invariance also forbids the use of cutoff. Otherwise explicit violation of scale invariance.
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Scale Current is Anomalous
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Scale Current is Anomalous
But dilatation current is anomalous!
Classical system with symmetry Quantize
Symmetry gone?!
But this is what we want!Quantum custodial symmetry
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Naturalness?
Beyond QFT
Just want to generate scale radiatively
Gravity is QFT
Fine-tuned but is technically nature
Want to have a chance to have technical natural theory without fine-tuning.
Unclear whether such scenario can be realized
Still need a UV theory to tell whether theory is fine-tuned or not
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
EW scale from CSI breaking
Start with classical scale invariant (CSI) lagrangian
Through RG evolution, the scalar potential develop flat direction, quantum correction shift the vev to non-vanishing value: Coleman-Weinberg
(Additional) gauge interaction grows strong and dynamically sets a condensation scale
EW scale is radiatively generated
Crucial:
Weakly
Strongly
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Dynamical chiral symmetry breaking of hidden fermions
The condensation scale is transferred to SM by Higgs portal.
Bonus: Dark pions as dark matter candidate
Holthausen, Kubo, KSL, Lindner '13Hur, Jung, Ko, Lee '11Hur, Ko '11Heikinheimo, Racioppi, Raidal, Spethmann, Tuominen '13
Idea:
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Concrete Model
Singlet mediator
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Concrete Model
● Advantage of having 3 dark color and 3 flavors = Can use QCD data to scale up spectrum● Nambu-Jona-Lasinio approach allows us to determine a lot of paramaters dynamically.● Less free parameters if we mimic QCD, but in general can be of any gauge group and
flavor.
Singlet mediator
NJL approach
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Constraining the Parameter Space
● To ensure that the theory survives up to Planck scale
● Mass of DM has to be smaller than hidden fermion's constituent mass
● Possible reason why
● Possible reason that QCD scale is lower than EW due to different number of flavor
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
After all the tedious algebras...
CP even scalar, mixes with h and S
Dark pions
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
After all the tedious algebras...
CP even scalar, mixes with h and S
Dark pions
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
After all the tedious algebras...
CP even scalar, mixes with h and S
Dark pions
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Effective Potential
Constituent mass for hidden fermionsFrom here we can calculate
mass spectrum of
Step 1
from QCD is used to calibrate the potential
Step 2
Obtain the minimum for the effective potential
Step 3
Fix the vev of h and scale up the rest of parameters
Step 4
Calculate the masses of scalar by first obtaining the inverse propagator
rotates flavor eigenstate to mass eigenstate
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Direct Detection Prospect
We may allow the imaginary parts in one-loop diagram, like in hadron physics.
Require
➔ Otherwise NJL is invalid
➔ Compare with strange quark constituent mass and Kaon mass
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Direct Detection Prospect
Limited Parameter Space can be probed by XENON1T!
Caused by restrictive parameter space and the need to satisfy the Higgs mass, mixing bound, relic density, perturbativity up to Planck scale, etc
NJL validity
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
CSI and Accidental U(1)
We can exploit this free lunch by identifying it with electromagnetism
Charged dark fermion
DM remains neutral
HESS limit
Highly non-trivial to use NJL approach while maintaining gauge invariance. Needs “least subtraction method” (More fun stuffs in our paper).
e.g. Q = 1/3
Still has U(1) symmetry in
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
What about gravity?
contains nasty ghost!
Conformal gravity
But this should better be order TeV, otherwise fine-tuning
propagator
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014
Summary
● A strongly coupled hidden sector model based on NJL where the spontaneous chiral symmetry breaking induces EWSB via singlet mediator.
● The strongly coupled hidden sector is a scaled up QCD → Less free parameter.
● The model provides natural DM candidates, i.e. the dark pions, which are stable under flavor symmetry.
● A QCD extension with scalar of larger irreducible representation that condenses at TeV scale, generating EW scale via dimensional transmutation.
● The mass of the extra scalar is very restrictive, and can be confirmed or ruled out by LHC.
● Higgs production rate in gluon fusion is suppressed. Accidental U(1) symmetry may enhance
● With no sign of new physics from LHC, long-held belief on naturalness should be scrutnized.
● Classical scale invariance might act as protective symmetry as alternative solution to hierarchy problem, and generates EW scale radiatively.
● We propose 2 models that generate EW scale dynamically.
A new way of model building?
Kher Sham Lim, Max-Planck-Institut für Kernphysik
Aspects of Classical Scale Invariance and Electroweak Symmetry BreakingITP Teilchen-Tee, November 2014