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Title: Heavy flavor and dark sector

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 91; Journal Issue: 1; Related Information: CHORUS Timestamp: 2017-04-06 12:08:40; Journal ID: ISSN 1550-7998
American Physical Society
Country of Publication:
United States

Citation Formats

Nelson, A. E., and Scholtz, J. Heavy flavor and dark sector. United States: N. p., 2015. Web. doi:10.1103/PhysRevD.91.014009.
Nelson, A. E., & Scholtz, J. Heavy flavor and dark sector. United States. doi:10.1103/PhysRevD.91.014009.
Nelson, A. E., and Scholtz, J. 2015. "Heavy flavor and dark sector". United States. doi:10.1103/PhysRevD.91.014009.
title = {Heavy flavor and dark sector},
author = {Nelson, A. E. and Scholtz, J.},
abstractNote = {},
doi = {10.1103/PhysRevD.91.014009},
journal = {Physical Review D},
number = 1,
volume = 91,
place = {United States},
year = 2015,
month = 1

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevD.91.014009

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Cited by: 3works
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  • A search is presented for an excess of events with heavy-flavor quark pairs (tt¯ and bb¯) and a large imbalance in transverse momentum in data from proton-proton collisions at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 2.2 fb –1 collected with the CMS detector at the CERN LHC. No deviations are observed with respect to standard model predictions. The results are used in the first interpretation of dark matter production in tt¯ and bb¯ final states in a simplified model. This analysis is also the first to perform a statistical combination of searchesmore » for dark matter produced with different heavy-flavor final states. Lastly, the combination provides exclusions that are stronger than those achieved with individual heavy-flavor final states.« less
  • We present a model of quark mass generation where the observed intergeneration mass hierarchy, large ratio {ital m}{sub {ital t}}{sup 2}/{ital m}{sub {ital b}}{sup 2}{much gt}1, and flavor mixing can all arise naturally. The basic assumption is that only the charge 2/3 quarks ({ital u}{sub {ital i}}; {ital i}=1,2,3) couple to heavy fermions {ital F} by emission and reabsorption of bosons {ital S}. The generation index dependence of the shape of the form factors at these {ital S{bar F}u}{sub {ital i}} couplings is responsible for the up-sector mass hierarchy. The {ital W}{sup {plus minus}} gauge bosons are assumed to havemore » a generation-index-independent anomalous-magnetic-moment-type correction to the standard {ital V}{minus}{ital A} coupling to quarks. This correction enables the charge {minus}1/3 quarks to acquire masses by coupling to the up-sector charge 2/3 quarks, which provides a natural explanation for {ital m}{sub {ital t}}{sup 2}{much gt}{ital m}{sub {ital b}}{sup 2}. Because the charge 2/3 quark self-energy matrix is probed here at a non-negligible momentum, the down-sector mass matrix turns out to be significantly different from the up-sector mass matrix, thus producting naturally smaller intergeneration mass ratios as well as flavor mixing and {ital CP} violation if the form factors are complex. In order to exhibit the remarkable properties of the above scheme, we use a concrete model for the form factors. We find for the particular scenarios {ital M}{sub {ital F}}{much gt}{Lambda} or {ital M}{sub {ital F}}{much lt}{Lambda} (where {Lambda} is a characteristic mass scale common to all form factors) simple analytical expressions for the mass matrices. Excellent 4 to 6 parameter fits to the 10 observables in the quark sector are obtained. All dimensionless input parameters are of order 1 and do not require fine-tuning.« less
  • Cosmological observations have revealed the existence of a dark matter sector, which is commonly assumed to be made up of one particle species only. However, this sector might be more complicated than we currently believe: there might be more than one dark matter species (for example, two components of cold dark matter or a mixture of hot and cold dark matter) and there may be new interactions between these particles. In this paper we study the possibility of multiple dark matter species and interactions mediated by a dark energy field. We study both the background and the perturbation evolution inmore » these scenarios. We find that the background evolution of a system of multiple dark matter particles (with constant couplings) mimics a single fluid with a time-varying coupling parameter. However, this is no longer true on the perturbative level. We study the case of attractive and repulsive forces as well as a mixture of cold and hot dark matter particles.« less
  • We show that the 't Hooft-Polyakov monopole model in the hidden sector with Higgs portal interaction makes a viable dark matter model, where monopole and massive vector dark matter (VDM) are stable due to topological conservation and the unbroken subgroup U(1 {sub X}. We show that, even though observed CMB data requires the dark gauge coupling to be quite small, a right amount of VDM thermal relic can be obtained via s-channel resonant annihilation for the mass of VDM close to or smaller than the half of SM higgs mass, thanks to Higgs portal interaction. Monopole relic density turns outmore » to be several orders of magnitude smaller than the observed dark matter relic density. Direct detection experiments, particularly, the projected XENON1T experiment, may probe the parameter space where the dark Higgs is lighter than ∼< 50 GeV. In addition, the dark photon associated with the unbroken U(1 {sub X} contributes to the radiation energy density at present, giving Δ N{sub eff}{sup ν} ∼ 0.1 as the extra relativistic neutrino species.« less
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