Raymundo Ramos

Korea Institute for Advanced Study

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Yue-Lin Sming Tsai

Purple Mountain Observatory

Tzu-Chiang Yuan

Institute of Physics, Academia Sinica

Sin Kyu Kang

Seoul National University of Science and Technology

Christopher D. Carone

Williams (United States)

Alexander J. Stuart

Universidad de Colima

Yang Hwan Ahn

Seoul National University of Science and Technology

Van Que Tran

Institute of Physics, Academia Sinica

Alfredo Aranda

Universidad de Colima

Cesar Bonilla

Universitat de València

Alma D. Rojas

Istituto Nazionale di Fisica Nucleare, Sezione di Torino

Cooperative Institutions

National Tsing Hua University

Seoul National University of Science and Technology

Universidad de Colima

University of Wisconsin–Madison

Chinese Academy of Sciences

Institute of Physics, Academia Sinica

National Center for Theoretical Sciences

National Center for Theoretical Sciences, Physics Division

National Taiwan Normal University

Williams (United States)

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Relic density and temperature evolution of a light dark sector

Physical review. D/Physical review. D. (2024)

Xin-Chen Duan Raymundo Ramos Yue-Lin Sming Tsai

We have developed a set of four fully coupled Boltzmann equations to precisely determine the relic density and temperature of dark matter by including three distinct sectors: dark matter, light scalar, and standard model sectors. The intricacies of heat transfer between dark matter (DM) and the standard model sector through a light scalar particle are explored, inspired by stringent experimental constraints on the scalar-Higgs mixing angle and the DM-scalar coupling. Three distinct sectors emerge prior to DM freeze-out, requiring fully coupled Boltzmann equations to accurately compute relic density. Investigation of forbidden, resonance, and secluded DM scenarios demonstrates significant deviations between established methods and the novel approach with fully coupled Boltzmann equations. Despite increased computational demands, this emphasizes the need for improved precision in relic density calculations, underlining the importance of incorporating these equations in comprehensive analyses. Published by the American Physical Society 2024

Boltzmann constant

10.1103/physrevd.110.063535

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Discovering charged Higgs bosons in theWplus dark vector boson decay mode

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology (2014)

Hooman Davoudiasl William J. Marciano Raymundo Ramos Marc Sher

In two-Higgs doublet extensions of the Standard Model, flavor-changing neutral current constraints can be addressed by introducing a $U(1{)}^{\ensuremath{'}}$ gauge symmetry, under which the Higgs doublets carry different charges. That scenario implies the presence of a ${H}^{\ifmmode\pm\else\textpm\fi{}}{W}^{\ensuremath{\mp}}{Z}^{\ensuremath{'}}$ vertex at tree level. For the light ``dark'' $Z$ model (${Z}^{\ensuremath{'}}={Z}_{d}$) with ${m}_{{Z}_{d}}<10\text{ }\text{ }\mathrm{GeV}$, such a coupling leads to the dominant decay mode ${H}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{W}^{\ifmmode\pm\else\textpm\fi{}}+{Z}_{d}$ (for ${m}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}\ensuremath{\lesssim}175\text{ }\text{ }\mathrm{GeV}$), rather than the usual type I model decay ${H}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\nu}$, for a broad range of parameters. We find that current analyses do not place significant bounds on this scenario. Over much of the parameter space considered, the decay of a pair-produced $t$ ($\overline{t}$) into ${H}^{+}b$ (${H}^{\ensuremath{-}}\overline{b}$) provides the dominant ${H}^{\ifmmode\pm\else\textpm\fi{}}$ production. Analysis of available LHC data can likely cover significant ranges of our parameters, if ${Z}_{d}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ has a branching ratio of $\ensuremath{\sim}20%$. If the ${Z}_{d}$ decays mainly invisibly then probing the entire relevant parameter space would likely require additional data from future LHC runs. We briefly discuss the phenomenology for ${m}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}\ensuremath{\gtrsim}175\text{ }\text{ }\mathrm{GeV}$.

Branching fraction

10.1103/physrevd.89.115008

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Predictions for the Leptonic Dirac CP-Violating Phase

arXiv (Cornell University) (2019)

Lisa L. Everett Raymundo Ramos Ariel B. Rock Alexander J. Stuart

We explore the theoretical constraints on the observable parameters of neutrino mixing on predictions for the leptonic Dirac CP-violating phase within a well-studied class of simple theoretical models that includes a single source of CP violation due to charged lepton corrections. The approach guarantees that a physically meaningful prediction for the most likely values for the leptonic Dirac CP-violating phase is obtained.

CP violation

10.48550/arxiv.1912.10139

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Flavored axion-monodromy inflation

Journal of Physics Conference Series (2016)

Raymundo Ramos

In this talk we consider the breaking of a flavor-symmetric potential as the origin of the pseudo-Goldstone bosons responsible for inflation. The breaking of flavor symmetry generates the fermion mass hierarchy while the breaking of accidental symmetries leads to pseudo-Goldstone bosons with an axion-monodromy potential appropriate for inflation. We deal with models where the inflaton is a linear combination of two fields. We will show that the mechanism by which inflation ends depends on the choice of parameters.

Monodromy

Goldstone boson

10.1088/1742-6596/761/1/012013

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The relic density and temperature evolution of light dark sector

arXiv (Cornell University) (2024)

Xin-Chen Duan Raymundo Ramos Yue-Lin Sming Tsai

We have developed a set of four fully coupled Boltzmann equations to precisely determine the relic density and temperature of dark matter by including three distinct sectors: dark matter, light scalar, and standard model sectors. The intricacies of heat transfer between DM and the SM sector through a light scalar particle are explored, inspired by stringent experimental constraints on the scalar-Higgs mixing angle and the DM-scalar coupling. Three distinct sectors emerge prior to DM freeze-out, requiring fully coupled Boltzmann equations to accurately compute relic density. Investigation of forbidden, resonance, and secluded DM scenarios demonstrates significant deviations between established methods and the novel approach with fully coupled Boltzmann equations. Despite increased computational demands, this emphasizes the need for improved precision in relic density calculations, underlining the importance of incorporating these equations in comprehensive analyses.

10.48550/arxiv.2404.12019

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Complementary searches of low mass non-Abelian vector dark matter, dark photon, and dark Z′

Physical review. D/Physical review. D. (2021)

Raymundo Ramos Tzu-Chiang Yuan Van Que Tran

We investigate a non-Abelian vector dark matter candidate ${W}^{\ensuremath{'}}$ with a MeV--GeV low mass range, accompanied by a dark photon ${A}^{\ensuremath{'}}$ and a dark ${Z}^{\ensuremath{'}}$ in the context of a gauged two-Higgs-doublet model. The model is scrutinized by considering various experimental constraints including dark photon searches, electroweak precision data, the relic density of dark matter together with its direct and indirect searches, monojet and Higgs data from the LHC. The viable parameter space indicates that while a dark ${Z}^{\ensuremath{'}}$ can be the dominant contribution in the relic density due to resonant annihilation of the dark matter, a dark photon is crucial to dark matter direct detection. The model can be further probed in the near future by sub-GeV dark matter and dark photon experiments.

Dark photon

Annihilation

Light dark matter

10.1103/physrevd.103.075021

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Citations (10)

Introducción a Bret Harte

Revista de la Universidad de México (1979)

Raymundo Ramos

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Confronting the prediction of leptonic Dirac CP -violating phase with experiments

Physical review. D/Physical review. D. (2022)

Yang Hwan Ahn Sin Kyu Kang Raymundo Ramos Morimitsu Tanimoto

We update and improve past efforts to predict the leptonic Dirac $CP$-violating phase with models that predict perturbatively modified tribimaximal or bimaximal mixing. Simple perturbations are applied to both mixing patterns in the form of rotations between two sectors. By translating these perturbed mixing matrices to the standard parametrization for the neutrino mixing matrix we derive relations between the Dirac $CP$ phase and the oscillation angles. We use these relations together with current experimental results to constrain the allowed range for the $CP$ phase and determine its probability density. Furthermore, we elaborate on the prospects for future experiments probing on the perturbations considered in this work. We present a model with ${A}_{4}$ modular symmetry that is consistent with one of the described perturbed scenarios and successfully predicts current oscillation parameter data.

10.1103/physrevd.106.095002

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Consistency of a gauged two-Higgs-doublet model: Scalar sector

Physical review. D/Physical review. D. (2018)

Abdesslam Arhrib Wei-Chih Huang Raymundo Ramos Yue-Lin Sming Tsai Tzu-Chiang Yuan

We study the theoretical and phenomenological constraints imposed on the scalar sector of the gauged two Higgs doublet model proposed recently as a variant of the popular inert Higgs doublet model of dark matter. The requirements of tree-level vacuum stability and perturbative unitarity in the scalar sector are analyzed in detail. Furthermore, taking into account the constraints from the 125 GeV Higgs boson measurements at the Large Hadron Collider, we map out the allowed ranges for the fundamental parameters of the scalar potential in the model.

Unitarity

Higgs sector

Scalar potential

Two-Higgs-doublet model

10.1103/physrevd.98.095006

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The Dark Z and Charged Higgs Decay

arXiv (Cornell University) (2013)

Raymundo Ramos Marc Sher

If there is an additional U(1) symmetry under which Standard Model particles are singlets, then there can be mixing between the additional gauge boson and the hypercharge gauge boson. This can lead to a very light, but weakly coupled "dark" gauge boson, the $Z_d$, with a mass of O(1) GeV. If the $Z_d$ gets its mass entirely from a Higgs singlet, it is called a dark photon; whereas if there is a second Higgs doublet, it is called a dark Z. We look at charged Higgs boson decays in the dark Z model. If the charged Higgs mass is between 90 GeV and 170 GeV, then its dominant two-body decays are $H^+ \rightarrow τ ν $ and $H^+ \rightarrow W^+ Z_d$. The former is suppressed by the small tau mass-squared and by $1/\tan^2 β$, whereas the latter is suppressed by a loop and a small mixing. We find that for much of the allowed parameter-space $H^+ \rightarrow W^+ Z_d$ will dominate. Since $Z_d$ decays to a lepton pair much of the time, this leads (using Drell-Yan pair production) to $pp \rightarrow H^+H^- \rightarrow W^+ W^-$ plus two highly collimated "lepton jets". Current bounds on lepton jets from ATLAS come close to constraining some of parameter space, and a dedicated search using the 2012 data would substantially improve the coverage.

Dark photon

10.48550/arxiv.1312.0013

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Citations (1)