Fundamental Symmetries - 3 Vincenzo Cirigliano Los Alamos National - - PowerPoint PPT Presentation

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Fundamental Symmetries - 3 Vincenzo Cirigliano Los Alamos National - - PowerPoint PPT Presentation

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HUGS 2018 Jefferson Lab, Newport News, VA May 29- June 15 2018 Fundamental Symmetries - 3 Vincenzo Cirigliano Los Alamos National Laboratory Plan of the lectures Review symmetry and symmetry breaking Introduce the Standard Model and

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Vincenzo Cirigliano Los Alamos National Laboratory

HUGS 2018 Jefferson Lab, Newport News, VA May 29- June 15 2018

Fundamental Symmetries - 3

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Plan of the lectures

  • Review symmetry and symmetry breaking
  • Introduce the Standard Model and its symmetries
  • Beyond the SM:
  • hints from current discrepancies?
  • effective theory perspective
  • Discuss a number of “worked examples”
  • Precision measurements: charged current (beta decays);

neutral current (Parity Violating Electron Scattering).

  • Symmetry tests: CP (T) violation and EDMs;

Lepton Number violation and neutrino-less double beta decay.

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Status of the Standard Model

  • Experimental hints pointing to new physics:
  • Neutrino mass
  • Sterile neutrinos?
  • Few-sigma discrepancies in precision physics
  • Muon g-2
  • Lepton universality in B meson decays
  • Neutron lifetime: beam vs bottle
  • …
  • Tested at the loop level in both electroweak and flavor sector
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What about neutrino masses?

arXiv:1010.4131

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  • Lorentz invariant “mass terms” for fermions
  • Neutrino mass requires new degrees of freedom
  • In the case of neutrinos:
  • option (1) requires introducing νR and using Higgs to

make it SU(2) gauge invariant (as for other fermions)

  • option (2) is not SU(2) gauge invariant

What about neutrino masses?

(1) (2)

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What about neutrino masses?

  • Neutrino mass requires new degrees of freedom
  • Simple / natural option: three R-handed neutrinos νRi (gauge singlets)

Both allowed by gauge symmetry Mass term breaks U(1)L

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SLIDE 7
  • Neutrino mass requires new degrees of freedom
  • Simple / natural option: three R-handed neutrinos νRi (gauge singlets)
  • Dirac neutrinos: MR = 0. Complete analogy to quark sector (B → L),

except for tiny (O(10-10)) Yukawa couplings

⇒

Unitary mixing in CC vertex: 3 angles, 1 phase

What about neutrino masses?

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  • Majorana neutrinos: MR≠ 0. L not conserved
  • In general 6x6 mass matrix for : six Majorana (ν=νc) eigenstates
  • If MR >> vYν: 3 light (νL→νi) and 3 heavy (νR→Ni) eigenstates

φ φ νR νR Yν* MR-1 Yν† νL νL We could have written this term without reference to νR and in SU(2) gauge-invariant form (more later)

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  • Majorana neutrinos: MR≠ 0. L not conserved
  • In general 6x6 mass matrix for : six Majorana (ν=νc) eigenstates
  • If MR >> vYν: 3 light (νL→νi) and 3 heavy (νR→Ni) eigenstates
  • Mixing of 3 light Majorana neutrinos:

⇒

Unitary mixing in CC vertex: 3 angles, 1+2 phases

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Neutrino phenomenology

  • LνSM probed at the Intensity Frontier (accelerator, reactor) and

Cosmic Frontier (solar, atmospheric, astro)

  • Oscillation experiments sensitive to mass splittings and mixing angles

Image credit: B. Kayser

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Neutrino phenomenology

  • LνSM probed at the Intensity Frontier (accelerator, reactor) and

Cosmic Frontier (solar, atmospheric, astro)

  • Oscillation experiments sensitive to mass splittings and mixing angles

Image credit: B. Kayser KAMLAND 2011

Reactor electron anti-neturino survival probability

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Neutrino phenomenology

World data consistent with 3 light states, but other light ν not excluded PDG 2014

11

  • LνSM probed at the Intensity Frontier (accelerator, reactor) and

Cosmic Frontier (solar, atmospheric, astro)

  • Oscillation experiments sensitive to mass splittings and mixing angles

mlightest2 = ?

NORMAL SPECTRUM INVERTED SPECTRUM

~7.5 10-5 eV2 ~2.4 10-3 eV2

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Neutrino phenomenology

  • A. de Gouvea

U

mlightest2 = ?

NORMAL SPECTRUM INVERTED SPECTRUM

~7.5 10-5 eV2

  • LνSM probed at the Intensity Frontier (accelerator, reactor) and

Cosmic Frontier (solar, atmospheric, astro)

  • Oscillation experiments sensitive to mass splittings and mixing angles

World data consistent with 3 light states, but other light ν not excluded ~2.4 10-3 eV2

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  • Many key aspects of ν dynamics remain unknown, and will be

explored by experiments in the next decade

  • Symmetries / particle content:
  • Is lepton number (L) broken? (Dirac vs Majorana)
  • Are there light sterile ν’s?

(0νββ) (short-baseline anomalies, cosmo)

  • Determine parameters of mass matrix (regardless its origin):
  • Absolute mass scale
  • Mass ordering
  • Mixing angles (✔), CPV phase

(beta decay, 0νββ*, cosmology*) (oscillation experiments)

Open questions

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Sterile neutrinos?

  • Anomalies in νe disappearance νe to νμ appearance data
  • Reactor anomaly: νe to νe (~3σ),

now independent of calculated flux

_ _

DANSS 1804.04046

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Sterile neutrinos?

  • Anomalies in νe disappearance νe to νμ appearance data
  • Reactor anomaly: νe to νe (~3σ),

now independent of calculated flux

_ _

DANSS 1804.04046

  • Short-baseline anomaly:

νμ to νe excess (4.8σ)

Mini-BooNE 1805.12028

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Sterile neutrinos?

  • Anomalies in νe disappearance νe to νμ appearance data
  • Global analysis in 3+1 scheme, using increasingly strong bounds on

νμ disappearance (MINOS+, …)

phase =

1803.10661

4.7σ tension between different data sets! MicroBooNE at FNAL will shed light on MiniBooNE excess (e vs γ discrimination)

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Status of the Standard Model

  • Experimental hints pointing to new physics:
  • Neutrino mass
  • Sterile neutrinos?
  • Few-sigma discrepancies in precision physics
  • Muon g-2
  • Lepton universality in B meson decays
  • Neutron lifetime: beam vs bottle
  • …
  • Tested at the loop level in both electroweak and flavor sector
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Muon anomalous magnetic moment

  • Dirac predicts g=2 in 1928
  • 1947: Measurements find ge≠2
  • Schwinger calculated

Great success of QED

  • D. Kawall
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  • How is gμ (aμ) measured?
  • Exploit the fact that

momentum and spin do not precess in the same way in a B field

  • Relative frequency ωa

proportional to (g-2)*B

  • D. Hertzog
  • Current experimental precision: Δge =5.2⨉10-13 and Δgμ=1.2⨉10-9
  • ge used to determine the electromagnetic coupling
  • gμ used to challenge the SM!
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SM theory Experiment vs

Dominant uncertainties: ongoing efforts to improve these results using Lattice QCD

  • Where are we?
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SM theory Experiment vs

Goal: 0.14 ppm

  • D. Hertzog

Establish confidence in error bar New g-2 at Fermilab (FNALE989) and J-PARCE34 will improve uncertainty factor of 4

Dominant uncertainties: ongoing efforts to improve these results using Lattice QCD

  • Where are we?
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SM theory Experiment vs

  • D. Hertzog

Dominant uncertainties: ongoing efforts to improve these results using Lattice QCD

  • Where are we?

?

New physics?

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Lepton universality in B decays

  • G. Onderwater, CIPANP 2018
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Lepton universality in B decays

  • G. Onderwater, CIPANP 2018

R(D*)

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Lepton universality in B decays

  • G. Onderwater, CIPANP 2018

R(D*)

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Lepton universality in B decays

  • G. Onderwater, CIPANP 2018

(not shown here)

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Neutron lifetime puzzle

  • B. Fornal, CIPANP 2018

Count the living

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Neutron lifetime puzzle

  • B. Fornal, CIPANP 2018

Count the living Count the dead

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Neutron lifetime puzzle

  • B. Fornal, CIPANP 2018
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Neutron lifetime puzzle

  • B. Fornal, CIPANP 2018
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Neutron lifetime puzzle

  • B. Fornal, CIPANP 2018

From 9Be stability

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Neutron lifetime puzzle

  • B. Fornal, CIPANP 2018

From 9Be stability