- The paper presents a detailed numerical study of quark mixing matrices, showing that differences in Cabibbo angles may lower the mass bound on the right-handed W boson.
- The paper compares parity and charge conjugation definitions of LR symmetry, finding that the charge conjugation scenario yields a stronger, CP-aligned mass limit.
- The paper highlights potential LHC signatures, such as same-sign dileptons, which could empirically validate LR symmetric theories and elucidate neutrino mass mechanisms.
Analysis of Left-Right Symmetry in Gauge Theories at LHC
The paper investigates the theoretical and experimental prospects of Left-Right (LR) symmetry models, particularly focusing on the Large Hadron Collider (LHC) capabilities to probe these theories. It revisits the scale of Left-Right symmetry breaking within the minimal SU(2)L × SU(2)_R × U(1){B-L} gauge theory framework, incorporating the seesaw mechanism. The emphasis is laid upon two possible definitions of LR symmetry: generalized parity (P) and charge conjugation (C).
Overview of Key Findings
1. Quark Mixing Matrix Analysis:
The paper provides a comprehensive numerical analysis of quark mass matrices and the left-right mixing matrices without relying on typical assumptions, such as ratios of vacuum expectation values (VEVs). It highlights the possible deviation between left and right Cabibbo angles, potentially lowering the existing bound on the mass of the right-handed W boson, typically found to be M_{W_R} > 2.5 TeV.
2. Differences in Symmetry Definitions:
- Parity (P): The paper suggests that in cases where Left-Right symmetry is parity, the analysis shows a slight reduction in the lower mass limit due to quark mixing angle differences. However, stronger bounds emerge from CP-violating observables unless the model is fine-tuned.
- Charge Conjugation (C): Defining LR symmetry as charge conjugation leads to a more robust limit on M_{W_R}, unaffected by CP-violating constraints. This definition aligns well with the observed CP violation in neutrino oscillations and possibly resolves tensions between Standard Model predictions and CP violations in the B sector.
3. Implications for Collider Experiments:
The findings suggest that both charged and neutral gauge bosons could be detectable at the LHC, potentially exhibiting prominent signatures of lepton number violation, such as same-sign dileptons, which are clear indicators of LR parity restoration and Majorana neutrino effects.
4. CP Violation Studies:
In-depth scrutiny of CP-violating phenomena within the B-meson systems underscores the distinct divergences between the P and C symmetries. The charge conjugation scenario notably matches the observed CP violations and sidesteps the tight restrictions that parity-based models face.
Implications and Future Directions
The paper’s results advocate a reaffirmation of LR symmetry models with gauge theories, particularly under the symmetry defined by charge conjugation. The suppression of CP-violating constraints in the C configuration provides a promising avenue for testing the minimal models at collider energies reachable by current or near-future LHC runs. The potential observation of unique LHC signatures could offer pivotal empirical evidence for LR models, opening new pathways for understanding neutrino masses and beyond-the-standard-model physics. These discussions encourage future research to explore the specific conditions under which these theories could manifest in observable particle physics experiments, particularly concerning the heavy neutrino sector and its implications for lepton number and flavor violations.
Overall, the paper extensively bridges theoretical predictions with feasible experimental verifications, rendering a coherent narrative that can invigorate LR symmetric theories' pursuit in contemporary particle physics.