Technicolor in the LHC Era is a fascinating research article authored by R. Sekhar Chivukula, Pawin Ittisamai, Jing Ren, and Elizabeth H. Simmons. Published in 2023, this study delves into the constraints and implications of the light technipion state predicted in technicolor models, particularly in the context of the Large Hadron Collider (LHC). In this article, we will explore the major findings and shed light on the significance of enhanced production rates of technipions compared to the standard Higgs Boson in technicolor models.
Understanding the Constraints on Technicolor Models
Technicolor models propose the existence of new particles and interactions that are responsible for electroweak symmetry breaking, a mechanism previously attributed to the Higgs Boson. In these models, technicolors replace the Higgs field, leading to the prediction of technipions as well. Technipions are composite particles, analogous to pions in Quantum Chromodynamics, and are expected to manifest at lower mass scales compared to the Higgs Boson.
The LHC, a particle accelerator located at CERN, has been instrumental in exploring the properties of the Higgs Boson and testing various theories, including technicolor models. Recent searches at the LHC, focusing on the decay modes of the Higgs Boson into gamma-gamma or tau-tau, have placed strong constraints on the existence of the light technipion. These constraints are relevant for technicolor models that involve colored technifermions, which play a crucial role in the formation of technicolor condensates.
The Enhanced Production Rate of Technipions
One of the key aspects investigated in this research is the enhanced production rate of technipions compared to the standard Higgs Boson. This enhanced production rate occurs due to two primary factors.
1. Technipion Decay Constant:
Technipions have a smaller decay constant compared to the weak scale. The decay constant essentially quantifies the strength of the interaction between the technipions and other particles. The smaller decay constant in technipions leads to an increase in the production rate, making them more accessible for detection at particle colliders such as the LHC. This enhanced production rate opens up new opportunities for studying the properties of technicolor models and provides a unique avenue for exploring beyond the Standard Model.
2. Suppression of WW Decays:
Another factor contributing to the enhanced production rate is the suppression of WW decays in technipions. In the Standard Model, the Higgs Boson predominantly decays into W boson pairs (WW) due to its strong coupling with the weak gauge bosons. However, in technicolor models, the WW decay of technipions is suppressed. As a result, the branching ratios of technipions into di-photon and di-tau final states are significantly enhanced compared to those of the Higgs Boson. This distinct feature provides a distinct signature for technipion searches at the LHC.
Searching for Higgs Bosons in Technicolor Models
The ATLAS and CMS experiments at the LHC have carried out extensive searches for Higgs bosons, including those within technicolor models. Several search strategies have been employed to hunt for technipions with masses ranging from 110 GeV up to nearly twice the top quark mass.
The researchers in this study specifically focused on technicolor models that fulfill certain criteria:
- Include colored technifermions: These models propose the existence of new particles in color charges, distinguished from the usual quarks and leptons present in the Standard Model. Colored technifermions are central to the theoretical foundations of technicolor models.
- Feature topcolor dynamics: Topcolor dynamics refer to the interaction of technicolor forces with the top quark. Including this aspect in technicolor models provides a more comprehensive picture of the underlying physics.
- Have technicolor groups with three or more technicolors (NTC > 3): Technicolor groups represent the number of different colors associated with the new particles introduced in technicolor models. Models with three or more technicolors come with distinct phenomenological consequences.
By considering these criteria, ATLAS and CMS have been able to exclude the presence of technipions within the defined mass range for the technicolor models under investigation.
Implications and Future Directions
The findings presented in this research article shed light on the properties of technicolor models in the LHC era. The enhanced production rate and modified branching ratios of technipions present exciting opportunities for studying physics beyond the Standard Model. To date, the absence of technipions within the search range poses important constraints on the specific technicolor models that were considered.
However, the research does not rule out the possibility of discovering technipions at higher energy scales or in alternative technicolor models that differ from the criteria mentioned above. It is essential to continue exploring and refining our understanding of electroweak symmetry breaking and the role of technicolor models in shaping the fundamental forces of nature.
As we move forward in the exploration of fundamental physics, technicolor and its associated particles offer a window into a deeper understanding of the universe. We eagerly await further experimental findings and theoretical developments that may unlock the secrets of technicolor and perhaps revolutionize our understanding of particle physics.
Sources:
“Technicolor in the LHC Era” by R. Sekhar Chivukula, Pawin Ittisamai, Jing Ren, Elizabeth H. Simmons. Available at: https://arxiv.org/abs/1202.1505
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