We construct a simple SO(10) SUSY GUT with D3 family symmetry and low energy R-parity. The model describes fermion mass matrices with 14 parameters and gives excellent fits to 20 observable masses ...and mixing angles in both quark and lepton sectors, giving 6 predictions. Bi-large neutrino mixing is obtained with hierarchical quark and lepton Yukawa matrices; thus avoiding the possibility of large lepton flavor violation. The model naturally predicts small 1–3 neutrino mixing, sinθ13≃0.05, and a CP violating phase δ close to π/2. Among other interesting predictions is a tiny effective Majorana mass for neutrinoless double-beta decay. Leptogenesis is also possible with the decay of the lightest right-handed neutrino giving an acceptable CP violating asymmetry ε1 of order 10−6, and with the correct sign for the resultant baryon asymmetry. Note, similar models with the non-Abelian symmetry groups SU(2) or D4, instead of D3, can be constructed.
We demonstrate that the next to minimal supersymmetric model can have small fine-tuning and modest top-squark mass while still evading all experimental constraints. For small tan(beta (large ...tan(beta), the relevant scenarios are such that there is always (often) a standard-model-like Higgs boson that decays to two lighter--possibly much lighter--Higgs pseudoscalars.
We use t, b, tau Yukawa unification to constrain supersymmetry parameter space. We find a narrow region survives for mu>0 (suggested by b-->sgamma and the anomalous magnetic moment of the muon) with ...A0 approximately -1.9m(16), m(10) approximately 1.4m(16), m(16) approximately 1200-3000 GeV and muM(1/2) approximately 100-500 GeV. Demanding Yukawa unification thus makes definite predictions for Higgs and sparticle masses.
We argue that given the experimental constraints on the Higgs boson mass the least fine-tuned parameter space of the minimal supersymmetric standard model is with negative top-squark masses squared ...at the grand unification scale. While the top-squark mass squared is typically driven to positive values at the weak scale, the contribution to the Higgs boson mass squared parameter from the running can be arbitrarily small, which reduces the fine-tuning of electroweak symmetry breaking. At the same time the top-squark mixing is necessarily enhanced and the maximal mixing scenario for the Higgs boson mass can be generated radiatively even when starting with negligible mixing at the unification scale. This highly alleviates constraints on possible models for supersymmetry breaking in which fine-tuning is absent.
We discuss magnetic monopoles in gauge theories with Wilson loops on orbifolds. We present a simple example in 5 dimensions with the fifth dimension compactified on an
S
1/
Z
2 orbifold. The Wilson ...loop in this
SO(3) example replaces the adjoint Higgs scalar (needed to break
SO(3) to
U(1)) in the well-known 't Hooft–Polyakov construction. Our solution is a magnetic monopole string with finite energy, and length equal to the size of the extra dimension.
We study the recently proposed scenario for SUSY GUT models in which compactification of the extra dimension(s) leads to a breakdown of the gauge symmetry and/or supersymmetry. SUSY breaking occurs ...on a hidden brane, and is communicated to the visible brane via gaugino mediation. The non-universal gaugino masses are developed at the compactification scale as a consequence of a restricted gauge symmetry on the hidden brane. For gaugino masses related due to a Pati–Salam symmetry on the hidden brane, we find the limited, but significant, regions of the model parameter space where a viable spectra of SUSY matter is generated. In the more general case of three independent gaugino masses, large parameter space regions open up for large values of the U(1) gaugino mass
M
1. We also find the relic density of neutralinos for these models to be generally below the expectations from cosmological observations, thus leaving room for hidden sector states to make up the bulk of cold dark matter.
Muon Collider Forum Report D Li; Maltoni, F; Acosta, D ...
arXiv (Cornell University),
08/2023
Paper, Journal Article
Odprti dostop
A multi-TeV muon collider offers a spectacular opportunity in the direct exploration of the energy frontier. Offering a combination of unprecedented energy collisions in a comparatively clean ...leptonic environment, a high energy muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. The topic generated a lot of excitement in Snowmass meetings and continues to attract a large number of supporters, including many from the early career community. In light of this very strong interest within the US particle physics community, Snowmass Energy, Theory and Accelerator Frontiers created a cross-frontier Muon Collider Forum in November of 2020. The Forum has been meeting on a monthly basis and organized several topical workshops dedicated to physics, accelerator technology, and detector R&D. Findings of the Forum are summarized in this report.
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