Based on:
1. arXiv: 1907.09498 [hep-ph], JHEP 03 (2020) 006 , in collaboration with K.S. Babu, B. Dev, A. Thapa
2. arXiv: 1908.02779 [hep-ph], Phys.Rev.Lett. 124 (2020) 4, 041805, in collaboration with K.S. Babu, B. Dev, Y. Sui
3. arXiv: 2007.04291 [hep-ph], JHEP 10 (2020) 040, in collaboration with K.S. Babu, Manfred Lindner

Outline• Neutrino magnetic andelectric dipole moments,
charge-radius

Theory ofradiative
neutrino massmechanism

Probe ofneutrino massmessenger

Understanding
neutrino
propertiesInvestigationof neutrino
interactions
with matter

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Neutrino Oscillations: Harbinger of New Physics
Neutrino flavor oscillations have been firmly established from:• Solar neutrinos (Homestake, SAGE, GALLEX, Kamiokande, SuperKamiokande, SNO, Borexino,…)• Atmospheric neutrinos (Super-Kamiokande, IceCube,…)• Reactor neutrinos (KamLand, DayaBay, RENO, DoubleChooz …)• Accelerator neutrinos (T2K, MINOS, NOVA…)Oscillations can happen only if neutrinos have non-zero masses• 𝝂𝜶 = 𝟑𝒊=𝟏 𝑼𝜶𝒊 𝝂𝒊,α = (e, µ, τ)• U is assumed to be unitary (Needs experimental check!)“Majorana phases” (α, β) do not affect the oscillation probabilities, while thesingle “Dirac phase” δ does
CP phase δ is unknown• Recent T2K result (Nature, 2020): δ = −𝟏. 𝟖𝟗+𝟎.𝟕𝟎−𝟎.𝟓𝟖

All three mixing angles and two mass splitting have been measured with few
percent precision
There is a mass ordering ambiguity, normal ordering vs. inverted ordering(Sign of Δm232 is currently unknown)

Unitarity of UPMNS remains to be tested

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Neutrino mass generation
 “ Technically natural” in t’Hooft sense.
Small values areprotected by symmetry. At a
cut-off scale Λ:“ natural ” - 𝛅mf ~ g2/(16𝛑2) mf ln(Λ2/mf2)“ unnatural ” - 𝛅mH2 ~ - yt2/(8𝛑2) Λ 2
Two ways to generate small values
naturally: Suppression by integrating out heavy states:
the higher dimension 1/Λn, the lower Λ can be.
 Suppression by loop radiative generation:
the higher loops 1/(16𝛑2)n, the lower cut off scale
can be.

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Radiative neutrino mass generation

Type-I Radiative Mechanism

Classification: Babu, Leung (2001),
de Gouvea, Jenkins (2008)
Volkas et al. (2017)

Babu, Dev, SJ, Thapa (2019)

Type-II Radiative MechanismNeutrino Standard Interaction(Wolfenstein)(Mikheyev-Smirnov)

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Neutrino NSI
Unknown couplings involving neutrinos.

Potentially observable effects in neutrino oscillation
experiments. It can affect mass ordering and CP violation.

NSI effects happen in the neutrino production, propagation
through matter, and the detection processes.

Most important effect of NSI is in neutrino propagation inmatter
Wolfenstein (1978)

There have been a variety of phenomenological studies of NSI
in the context of oscillations, but relatively lesser effort hasgone into the UV completion of models that yield such NSI.

A major challenge in generating sizable NSI: charged lepton
flavor violation

SUDIP JANA | MPIK9NSI in radiative neutrino mass models
An alternative to high scale seesaw for neutrino mass
generation is “radiative mechanism”

Small, finite Majorana masses are generated at thequantum level.

Neutrino mass

The charged scalars induce NSI at tree level

Smallness of neutrino mass is explained via loop andchiral suppression.

Simple realization is the Zee Model, which has a second
Higgs doublet and a charged singlet.

We have systematically analyzed these models for theirpredicted NSI.

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10Zee model

SUDIP JANA | MPIK11NSI in Zee model

SUDIP JANA | MPIK12NSI in Zee modelBabu, Dev, SJ, Thapa (2019)

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13NSI in Zee modelBabu, Dev, SJ, Thapa (2019)
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Charged lepton flavor violation

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Charged lepton flavor violation

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Collider constraints

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Collider constraints

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Collider constraints

Babu, Dev, SJ, Thapa (2019)

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Collider constraints

Babu, Dev, SJ, Thapa (2019)

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Constraints from Higgs observablesBabu, Dev, SJ, Thapa (2019)
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EW precision constraints

Babu, Dev, SJ, Thapa (2019)
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Charge breaking minimaBabu, Dev, SJ, Thapa (2019)
SUDIP JANA | MPIK23NSI in Zee modelBabu, Dev, SJ, Thapa (2019)
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Consistency with neutrino oscillation dataBabu, Dev, SJ, Thapa (2019)
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Zee-Burst: A new test of NSI at IceCubeBabu, Dev, SJ , Sui (PRL’ 2019)
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NSI in Zee-Babu model

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NSI in Zee-Babu model

SUDIP JANA | MPIK28NSI in KNT model

SUDIP JANA | MPIK29NSI in 1-loop LQ (colored-Zee) model

SUDIP JANA | MPIK30NSI in 2-loop LQ model

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31NSI in 3-loop LQ model

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Collider constraints on leptoquarks

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Collider constraints on leptoquarks

Babu, Dev, SJ , Thapa (2019)

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Other constraints on leptoquarks

SUDIP JANA | MPIK35NSI via leptoquarks in radiative models

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Summary of NSI in radiative models

Babu, Dev, SJ , Thapa (2019)
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Summary of NSI in radiative models

Babu, Dev, SJ , Thapa (2019)
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Conclusion

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