Uncovering the root of LEFT in SMEFT

Topic

natural sciences

Frequently Asked Questions (FAQ)

What are LEFT and SMEFT and why are they important for understanding physics beyond the Standard Model (BSM)? LEFT (Low Energy Effective Field Theory) describes physics below the electroweak scale, crucial for analyzing weak decays of leptons, B-mesons, and Kaons, which are sensitive to new physics. SMEFT (Standard Model Effective Field Theory) extends the Standard Model to energies up to at least 1 TeV, including all possible interactions allowed by Standard Model symmetries. It’s essential for interpreting data from high-energy colliders like the LHC. Both LEFT and SMEFT bridge low-energy precision measurements and high-energy collider searches in our quest for BSM physics.
How are LEFT and SMEFT operators classified? Operators in both LEFT and SMEFT are categorized by: Dimension: Reflects importance at different energy scales; higher-dimensional operators are suppressed at lower energies. Baryon (B) and Lepton (L) number violation: Signals BSM physics and can lead to phenomena like proton decay.
How are LEFT and SMEFT connected? LEFT operators can be embedded within SMEFT operators with matching (∆B, ∆L) values. The connection involves: Replacing Higgs fields with their vacuum expectation value after electroweak symmetry breaking. Rotating electroweak gauge bosons due to mixing of W and B gauge bosons. These relationships are visualized in a network mapping LEFT operator classes onto SMEFT classes.
What can we learn about UV physics by studying this connection? The mapping between LEFT and SMEFT helps understand the high-energy origins of low-energy BSM signals, tracing back through the network to pinpoint responsible SMEFT operators and possible UV-complete theories.
How does the LEFT cut-off scale relate to the SMEFT scale and the scale of new physics? The LEFT cut-off scale (ΛH) signifies where LEFT breaks down: ΛH ~ mW: LEFT operators originate from integrating out heavy Standard Model particles. ΛH ∈ {ΛS, ΛBSM}: B and L violating LEFT operators must arise from BSM physics, linked to the SMEFT scale (ΛS) or intermediate scales.
What are some examples of rare processes that provide insights into BSM physics? Examples include: Proton decay (e.g., p → K+e+e-ν): Indicates B violation. Neutron-antineutron oscillations: Indicates B violation by two units. Neutrinoless quadruple beta decay: Lepton-number violating process providing information about neutrino masses.
Can the LEFT-SMEFT network be used to study scenarios with light non-SM particles? Yes, the network can accommodate light BSM particles, expanding LEFT operator classes and leading to richer phenomenology.
What is the overall significance of this LEFT-SMEFT network? The network provides a roadmap for BSM physics exploration: Guides the search for rare processes. Connects low-energy experiments with high-energy colliders. Constrains the landscape of possible BSM theories.

Significance

Understanding these findings helps advance our knowledge and inform better decisions. This research represents an important contribution to the field. For the full details, watch the video above and explore the linked resources.

Resources & Further Watching

Read the paper: https://arxiv.org/pdf/2011.00859

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uncovering the root of left in smeft

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