arXiv subjects

George W. -S. Hou

Publications and source records attributed to George W. -S. Hou.

12 recordsLinked to original sources

arXiv2023

Study of 3-dimensional SU(2) gauge theory with adjoint Higgs as a model for cuprate superconductors

We study a 3-dimensional SU(2) gauge theory with 4 Higgs fields which transform under the adjoint representation of the gauge group, that has been recently proposed by Sachdev et al. to explain the physics of cuprate superconductors near optimal doping. The symmetric confining phase of the theory corresponds to the usual Fermi-liquid phase while the broken (Higgs) phase is associated with the interesting pseudogap phase of cuprates. We employ the Hybrid Monte-Carlo algorithm to study the phase diagram of the theory. We find the existence of a variety of broken phases in qualitative accordance with earlier mean-field predictions and discuss their role in cuprates. In addition, we investigate the behavior of Polyakov loop to probe the confinement/deconfinement phase transition, and find that the Higgs phase hosts a stable deconfining phase consistent with previous studies.

hep-lat↗

arXiv2022

Study of SU(2) gauge theories with multiple Higgs fields in different representations

We study two different SU(2) gauge-scalar theories in 3 and 4 spacetime dimensions. Firstly, we focus on the 3 dimensional SU(2) theory with multiple Higgs fields in the adjoint representation, that can be mapped to cuprate systems in condensed matter physics which host a rich phase diagram including high-Tc superconductivity. It has been proposed that the theory with 4 adjoint Higgs fields can be used to explain the physics of hole-doped cuprates for a wide range of parameters. We show exploratory results on the phase diagram of the theory. On the other hand, we are interested in the 4 dimensional theory with 2 sets of fundamental scalar (Higgs) fields, which is relevant to the 2 Higgs Doublet Model (2HDM), a proposed extension to the Standard Model of particle physics. The goal is to understand the particle spectrum of the theory at zero temperature and the electroweak phase transition at finite temperature. We present exploratory results on scale setting and the multi-parameter phase diagram of this theory.

hep-lat↗

arXiv2019

Curious Link of Exclusive and Inclusive CPV in Charmless 3-body B+ Decays

The LHCb experiment has measured CP violation (CPV) across the Dalitz plot of charmless decays of B+ mesons to 3 charged tracks, namely in Kππ, KKK, πππ and πKK final states, with strikingly large CPV that vary strongly with Dalitz variables. Identifying these processes with b -> sqq(bar), sss(bar) and b -> dqq(bar), dss(bar), where q = u, d, then the "sum rule" that requires two-loop absorptive parts by unitarity works well for inclusive b -> s CPV, but less well for inclusive b -> d case. We elucidate the situation, and argue that the 30 year old unitarity/CPT argument is valid to this day, while affirming quark-hadron duality.

hep-ph↗

arXiv2019

Top-Higgs Associated Production involving {\boldmath ${A^0},\, {H^0}$} with Mass at 300 GeV

We advocate two Higgs doublet model without $Z_2$ symmetry, and focus on the extra top Yukawa couplings $ρ_{tt}$ and $ρ_{tc}$. We show that $A^0$ and $H^0$ bosons are still allowed at 300 GeV mass, where $cg \to tA^0$, $tH^0$ can lead to $tt\bar c$ same-sign top, or top-assisted di-Higgs $th^0h^0$ signatures, resp. As bonus material, we explore the constraint provided by current 4-top search, but advocate direct search for triple-top generated by $cg \to tH^0/A^0 \to tt\bar t$ for $H^0,\, A^0$ above $t\bar t$ threshold, and offer some insight on the mild but intriguing "excess" found by CMS in $gg \to A^0 \to t\bar t$ at 400 GeV.

hep-ph↗

arXiv2017

Two Top Utilities of Two Higgs Doublets: Electroweak Baryogenesis and Alignment

With two Higgs doublets but without any discrete $Z_2$ symmetry to forbid flavor changing neutral Higgs couplings, new top Yukawa couplings $ρ_{tt}$ and $ρ_{tc}$ are allowed and naturally complex. Electroweak baryogenesis is remarkably efficient if both $ρ_{tt}$ (and $ρ_{tc}$) and exotic Higgs quartic couplings are ${\cal O}(1)$. Furthermore, the alignment phenomenon, that the observed 125 GeV boson so closely resembles the Standard Model Higgs boson, emerges naturally. One not only has many new flavor and CPV phenomena (modulo SM-like flavor organization plus alignment), but the exotic Higgs bosons $H^0$, $A^0$ and $H^+$ are necessarily sub-TeV in mass, and LHC search should be readjusted.

hep-ph↗

arXiv2017

$P_5'$ Anomaly for Top: $tZ'$ Production at LHC

The $P_5'$ anomaly uncovered by the LHCb experiment in $B \to K^*μμ$ angular observables has motivated a possible $Z'$ boson that couples to left-handed $b \to s$ transitions, where a model would be gauged $L_μ- L_τ$ symmetry, but direct search for such a $Z'$ is not promising. Less constrained is an analogous $Z'$ coupling to right-handed $t \to c$ transitions. Motivated by this, we study $cg \to tZ'$ associated production at LHC, both for a generic model, and in $L_μ- L_τ$ with a vector-like U quark. We also study $c\bar c \to Z'$ production that exists within the model. Both processes can be probed already with LHC Run 2 data, all the way up to the HL-LHC with discovery potential.

hep-ph↗

arXiv2017

ElectroWeak BaryoGenesis via Top Transport

We study electroweak baryogenesis driven by the top quark in two Higgs doublet model that allows flavor-changing neutral Higgs couplings. Taking Higgs sector couplings and the additional top Yukawa coupling $ρ_{tt}$ to be $\mathcal{O}$(1), one naturally has first order electroweak phase transition and sufficient $CP$ violation to fuel the cosmic baryon asymmetry. Even if $ρ_{tt}$ vanishes, the favor-changing coupling $ρ_{tc}$ can still achieve baryogenesis. Phenomenological consequences such as $t\to ch$, $τ\to μγ$, electron electric dipole moment, $h\toγγ$, and $hhh$ coupling are discussed. The extra scalars $H^0$, $A^0$ and $H^\pm$ are sub-TeV in mass, and can be searched for at the LHC.

hep-ph↗

arXiv2014

Neutrino Telescope Array (NTA) - Towards Survey of Astronomical $ν_τ$ Sources

The Earth-skimming $ν_τ$ method allows for huge target mass and detection volume simultaneously. In part motivated by IceCube PeV astro-neutrino events, the planned NTA observatory has three site stations watching the air mass surrounded by Mauna Loa, Mauna Kea, and Hualalai on Hawaii Island, plus a site station at the center watching the lower night sky. Sensitivities equivalent to $> 100$ km$^3$ water and pointing accuracy of $< 0.2^\circ$ can be achieved with Cherenkov-fluorescence stereoscopic observation for PeV-EeV neutrinos that is almost background-free. With design based on experience from Ashra-1 and the goal of clear discovery and identification of astronomical $ν_τ$ sources, a new international collaboration is being formed.

astro-ph.IM↗

arXiv2013

The phase structure of a chirally-invariant Higgs-Yukawa model

We present new results of our ongoing project on the investigation of the phase structure of the Higgs-Yukawa model at small and large bare Yukawa couplings. The critical exponents of the second order bulk phase transitions of this model are determined from finite-size analyses and compared to the pure O(4)-model to test for triviality and the possibility of having a non-Gaussian fixed point. In addition, we will present a first study of Higgs boson masses and fermion correlation functions.

hep-lat↗

arXiv2012

Investigation of the phase structure of a chirally-invariant Higgs-Yukawa model

We present new data on our ongoing project on the investigation of the phase structure of the Higgs-Yukawa model at large bare Yukawa couplings. The data presented last year are extended in terms of statistics, the number of bare Yukawa couplings at existing, and new larger volumes. In addition, this study is extended by a finite temperature project at the physical top quark mass m_t =175 GeV and a hypothetical fourth generation top quark with a mass of m_t' =700 GeV .

hep-lat↗

arXiv2012

Theory Summary {\large (a Perspective}

This is the Theory Summary of the "Flavor Physics and CP Violation 2012" conference, with emphasis on New Physics. Besides covering the theory part of the conference, we pay attention also to the physics highlights of experimental talks. I then give my perspective on the false "Godot sightings" of the past decade, with some firsthand accounts. With all coming to naught (well, SM) at the moment, I look ahead to the near future, and to 2015 and beyond. An Epilogue is added with the advent of "the Higgs" at the LHC.

hep-ph↗

arXiv2011

Study of the Higgs-Yukawa theory in the strong-Yukawa coupling regime

In this article, we present an ongoing lattice study of the Higgs-Yukawa model, in the regime of strong-Yukawa coupling, using overlap fermions. We investigated the phase structure in this regime by computing the Higgs vacuum expectation value, and by exploring the finite-size scaling behaviour of the susceptibility corresponding to the magnetisation. Our preliminary results indicate the existence of a second-order phase transition when the Yukawa coupling becomes large enough, at which the Higgs vacuum expectation value vanishes and the susceptibility diverges.

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