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Open Access Publications from the University of California

Scholarly Works (4 results)

  • Thesis
  • Peer Reviewed
UC Santa Cruz Electronic Theses and Dissertations (2020)

The Standard Model (SM) of particles physics is an extremely successful theory of particles and their interactions. However, it has become clear that the SM is an incomplete description of our Universe and that new physics beyond the SM (BSM) is needed to answer many of its open questions. In this talk we will discuss two open questions.

In the first part, we will present a model that can address the SM flavor puzzle. The hierarchical pattern in quark masses and mixings can be explained by assuming that the SM Higgs only generates mass for the 3rd generation fermions, while an additional source of electroweak symmetry breaking generates mass for the 1st and 2nd generations. Such a scenario can be realized in a ``flavorful'' two Higgs doublet model (2HDM). The characteristic Higgs collider signatures of this setup differ significantly from well-studied 2HDMs with natural flavor conservation. The presence of large SM Higgs flavor violating couplings can lead to enhanced rare top quark decays. We will also discuss some possible UV completions of this scenario.

In the second part, we will discuss a vector leptoquark scenario that can address the lepton flavor universality anomalies observed by the LHCb collaboration in B meson decays. We will show that a vector leptoquark solution of the B-anomalies can also alleviate discrepancies between the SM predictions and the experimental values of the electron and muon anomalous magnetic moments. In addition, leptoquark models generically yield new sources of CP violation that induce electric and magnetic dipole moments of elementary particles. We will show that present and future electron and neutron EDM experiments set interesting constraints on the CP violating phases of the leptoquark couplings.

    Cover page: Searching for Beyond Standard Model physics at Low and High Energy experiments
    • Article
    • Peer Reviewed
    UC Santa Cruz Previously Published Works (2020)
    Vector leptoquarks can address the lepton flavor universality anomalies in decays associated with the $b \to c \ell u$ and $b \to s \ell \ell$ transitions, as observed in recent years. Generically, these leptoquarks yield new sources of CP violation. In this paper, we explore constraints and discovery potential for electric dipole moments (EDMs) in leptonic and hadronic systems. We provide the most generic expressions for dipole moments induced by vector leptoquarks at one loop. We find that $O(1)$ CP-violating phases in tau and muon couplings can lead to corresponding EDMs within reach of next-generation EDM experiments, and that existing bounds on the electron EDM already put stringent constraints on CP-violating electron couplings.
      Cover page: Implications for Electric Dipole Moments of a Leptoquark Scenario for the $B$-Physics Anomalies
      • Article
      UC Irvine Previously Published Works (2021)
      The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF's physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.
        Cover page: The Forward Physics Facility: Sites, Experiments, and Physics PotentialCreative Commons 'BY' version 4.0 license
        • Article
        • Peer Reviewed
        UC Irvine Previously Published Works (2023)
        High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.
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