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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Chiral and deconfinement phase transitions in QED{sub 3} with finite gauge boson mass

Based on the experimental observation that there is a coexisting region between the antiferromagnetic (AF) and d-wave superconducting (dSC) phases, the influences of gauge boson mass m{sub a} on chiral symmetry restoration and deconfinement phase transitions in QED{sub 3} are investigated simultaneously within a unified framework, i.e., Dyson–Schwinger equations. The results show that the chiral symmetry restoration phase transition in the presence of the gauge boson mass m{sub a} is a typical second-order phase transition; the chiral symmetry restoration and deconfinement phase transitions are coincident; the critical number of fermion flavors N{sup c}{sub f} decreases as the gauge boson mass m{sub a} increases, which implies that there exists a boundary that separates the N{sup c}{sub f}–m{sub a} plane into chiral symmetry breaking/confinement region for (N{sup c}{sub f}, m{sub a}) below the boundary and chiral symmetry restoration/deconfinement region for (N{sup c}{sub f}, m{sub a}) above it.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

Gauge bosons masses in a SU(2){sub TC} x SU(3){sub L} x U(1){sub X} extension of the standard model

In this brief report we explore the full realization of the dynamical symmetry breaking of an 3-3-1 model to U(1){sub em} considering a model based on SU(2){sub TC} x SU(3){sub L} x U(1){sub X}. We compute the mass generated for the charged and neutral gauge bosons of the model that result from the symmetry breaking, and verify the equivalence between a 3-3-1 model with a scalar content formed by the set of the fundamental scalar bosons {chi},{rho} and {eta} with a 3-3-1 model where the dynamical symmetry breaking is implanted by the system formed by the set of composite bosons {Phi}{sub T},{Phi}{sub TC(1)} and {Phi}{sub TC(2)}. In this model the minimal composite scalar content is fixed by the condition of the cancellation of triangular anomaly in the technicolor (TC) sector.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

High-scale supersymmetry, the Higgs boson mass, and gauge unification

Suppressing naturalness concerns, we discuss the compatibility requirements of high-scale supersymmetry breaking with the Higgs boson mass constraint and gauge coupling unification. We find that to accommodate superpartner masses significantly greater than the electroweak scale, one must introduce large nondegeneracy factors. These factors are enumerated for the Minimal Supersymmetric Standard Model, and implications for the allowed forms of supersymmetry breaking are discussed. We find that superpartner masses of arbitrarily high values are allowed for suitable values of tan β and the nondegeneracy factors. Here, we also compute the large, but viable, threshold corrections that would be necessary at the unification scale for exact gauge coupling unification. Whether or not high-scale supersymmetry can be realized in this context is highly sensitive to the precise value of the top quark Yukawa coupling, highlighting the importance of future improvements in the top quark mass measurement.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Detection of cosmic superstrings by geodesic test particle motion

(p,q)-strings are bound states of p F-strings and q D-strings and are predicted to form at the end of brane inflation. As such, these cosmic superstrings should be detectable in the Universe. In this paper we argue that they can be detected by the way that massive and massless test particles move in the space-time of these cosmic superstrings. In particular, we study solutions to the geodesic equation in the space-time of field theoretical (p,q)-strings. The geodesics can be classified according to the test particles' energy, angular momentum and momentum in the direction of the string axis. We discuss how the change of the magnetic fluxes, the ratio between the symmetry-breaking scale and the Planck mass, the Higgs-to-gauge-boson mass ratios and the binding between the F- and D-strings, respectively, influence the motion of the test particles. While massless test particles can move only on escape orbits, a new feature as compared to the infinitely thin string limit is the existence of bound orbits for massive test particles. In particular, we observe that--in contrast to the space-time of a single Abelian-Higgs string--bound orbits for massive test particles in (p,q)-string space-times are possible if the Higgs boson mass is larger than the gauge boson mass. We also compute the effect of the binding between the p- and the q-string on observables such as the light deflection and the perihelion shift. While light deflection can also be caused by other matter distributions, the possibility of a negative perihelion shift seems to be a feature of finite width cosmic strings that could lead to the unmistakable identification of such objects. In Melvin space-times, which are asymptotically nonconical, massive test particles have to move on bound orbits, while massless test particles can escape to infinity only if their angular momentum vanishes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Naturally light Dirac neutrino in Left-Right Symmetric Model

We study the possibility of generating tiny Dirac masses of neutrinos in Left-Right Symmetric Model (LRSM) without requiring the existence of any additional symmetries. The charged fermions acquire masses through a universal seesaw mechanism due to the presence of additional vector like fermions. The neutrinos acquire a one-loop Dirac mass from the same additional vector like charged leptons without requiring any additional discrete symmetries. The model can also be extended by an additional Z {sub 2} symmetry in order to have a scotogenic version of this scenario predicting a stable dark matter candidate. We show that the latest Planck upper bound on the effective number of relativistic degrees of freedom N {sub eff}=3.15 ± 0.23 tightly constrains the right sector gauge boson masses to be heavier than 3.548 TeV . This bound on gauge boson mass also affects the allowed values of right scalar doublet dark matter mass from the requirement of satisfying the Planck bound on dark matter relic abundance. We also discuss the possible implications of such a scenario in charged lepton flavour violation and generating observable electric dipole moment of leptons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

LHC signals for coset electroweak gauge bosons in warped/composite pseudo-Goldstone boson Higgs models

The framework of a warped extra dimension with the standard model (SM) fields propagating in it is a very well-motivated extension of the SM since it can address both the Planck-weak and flavor hierarchy problems of the SM. Within this framework, solution to the little hierarchy problem motivates extending the SM electroweak (EW) 5D gauge symmetry in such a way that its breakdown to the SM delivers the SM Higgs boson. We study signals at the large hadron collider (LHC) for the extra EW (called coset) gauge bosons, a fundamental ingredient of this framework. The coset gauge bosons, due to their unique EW gauge quantum numbers [doublets of SU(2){sub L}], do not couple at leading order to two SM particles. We find that, using the associated production of the charged coset gauge bosons via their coupling to bottom quark and a (light) Kaluza-Klein excitation of the top quark, the LHC can have a 3{sigma} reach of {approx}2(2.6) TeV for the coset gauge boson masses with {approx}100(1000) fb{sup -1} luminosity. Since current theoretical framework(s) suggest an indirect lower limit on coset gauge boson masses of > or approx. 3 TeV, luminosity or energy upgrade of LHC is likely to be crucial in observing these states.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Gauge boson signals at the cosmological collider

We study the production of massive gauge bosons during inflation from the axion-type coupling to the inflaton and the corresponding oscillatory features in the primordial non-Gaussianity. In a window in which both the gauge boson mass and the chemical potential are large, the signal is potentially reachable by near-future large scale structure probes. This scenario covers a new region in oscillation frequency which is not populated by previously known cosmological collider models. We also demonstrate how to properly include the exponential factor and discuss the subtleties in obtaining power dependence of the gauge boson mass in the signal estimate.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Fermion mass hierarchy and phenomenology in the 5D Domain Wall Standard Model

We have recently proposed a setup of the “Domain-Wall Standard Model” in 5D spacetime, where all the Standard Model (SM) fields are localized in certain domains of the extra 5th dimension. Utilizing this setup, we attempt to solve the fermion mass hierarchy problem of the SM. The mass hierarchy can be naturally explained by suitably distributing the fermions in different positions along the extra dimension. Due to these different localization points, the effective 4D gauge couplings of Kaluza-Klein (KK) mode gauge bosons to the SM fermions become non-universal. As a result, our model is severely constrained by the Flavor Changing Neutral Current (FCNC) measurements. We find two interesting cases in which our model is phenomenologically viable: (1) the KK-mode of the SM gauge bosons are extremely heavy and unlikely to be produced at the Large Hadron Collider (LHC), while future FCNC measurements can reveal the existence of these heavy modes. (2) the width of the localized SM fermions is very narrow, leading to almost universal 4D KK-mode gauge couplings. In this case, the FCNC constraints can be easily avoided even if a KK gauge boson mass lies at the TeV scale. Such a light KK gauge boson can be searched at the LHC in the near future.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

Family gauge bosons with an inverted mass hierarchy

A model that gives family gauge bosons with an inverted mass hierarchy is proposed, stimulated by Sumino's cancellation mechanism for the QED radiative correction to the charged lepton masses. The Sumino mechanism cannot straightforwardly be applied to SUSY models because of the non-renormalization theorem. In this talk, an alternative model which is applicable to a SUSY model is proposed. It is essential that family gauge boson masses m(A{sub i}{sup j}) in this model is given by an inverted mass hierarchy m(A{sub i}{sup i}){proportional_to}1/{radical}(m{sub ei}), in contrast to m(A{sub i}{sup i}){proportional_to}{radical}(m{sub ei}) in the original Sumino model. Phenomenological meaning of the model is also investigated. In particular, we notice a deviation from the e-{mu} universality in the tau decays.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Upper limits on a possible gluon mass

We analyze upper limits on a possible gluon mass, m{sub g}. We first discuss various ways to modify quantum chromodynamics to include m{sub g{ne}}0, including a bare mass, a Higgs mechanism, and dynamical breaking of color SU(3){sub c}. From an examination of experimental data, we infer an upper limit m{sub g}<O(1) MeV. As part of our analysis, we show that a claim, hitherto unrefuted in the literature, of a much stronger upper limit on m{sub g}, is invalid. We discuss subtleties in interpreting gluon mass limits in view of the fact that at scales below {Lambda}{sub QCD}, quantum chromodynamics is strongly coupled, perturbation theory is not reliable, and the physics is not accurately described in terms of the Lagrangian degrees of freedom, including gluons. We also point out a fundamental difference in the behavior of quantum chromodynamics with a nonzero gluon mass and a weakly coupled gauge theory with a gauge boson mass.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Supersymmetric gauged $ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $ model for electron and muon (g - 2) anomaly

Minimal gauged U 1 L μ - L τ models can provide for an additional source for the muon anomalous magnetic moment however it is difficult to accommodate the discrepancy in the electron magnetic moment in tandem. Owing to the relative sign between the discrepancies in these quantities, it seems unlikely that they arise from the same source. We show that a supersymmetric (SUSY) gauged U 1 L μ - L τ model can accommodate both the muon and electron anomalous magnetic moments in a very simple and intuitive scenario, without utilizing lepton flavor violation. The currently allowed parameter space in this kind of a scenario is constrained from the latest LHC and various low energy experimental data,e.g., recent COHERENT data, CCFR, Borexino, BaBaR, supernova etc. These constraints, in conjunction with the requirement to explain both lepton magnetic moments, lead to an upper bound on the first generation slepton mass, a lower bound on the second generation slepton mass and constricts the allowed range for the new gauge boson mass and coupling. The scheme can be probed at the ongoing COHERENT and Coherent CAPTAIN-Mills experiments and at future experiments, e.g., DUNE, BELLE-II etc.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Baryogenesis in a parity solution to the strong CP problem

Abstract Space-time parity can solve the strong CP problem and introduces a spontaneously broken SU(2) R gauge symmetry. We investigate the possibility of baryogenesis from a first-order SU(2) R phase transition similar to electroweak baryogenesis. We consider a model with the minimal Higgs content, for which the strong CP problem is indeed solved without introducing extra symmetry beyond parity. Although the parity symmetry seems to forbid the SU(2) R anomaly of theB−Lsymmetry, the structure of the fermion masses can allow for the SU(2) R sphaleron process to produce non-zeroB−Lasymmetry of Standard Model particles so that the wash out by the SU(2) L sphaleron process is avoided. The setup predicts a new hyper-charged fermion whose mass is correlated with the SU(2) R symmetry breaking scale and hence with the SU(2) R gauge boson mass, and depending on the origin of CP violation, with an electron electric dipole moment. In a setup where CP violation and the first-order phase transition are assisted by a singlet scalar field, the singlet can be searched for at future colliders.

Physics↗
DOE OSTI2015

Relic neutralino surface at a 100 TeV collider

We map the parameter space for minimal supersymmetric Standard Model neutralino dark matter which freezes out to the observed relic abundance, in the limit that all superpartners except the neutralinos and charginos are decoupled. In this space of relic neutralinos, we show the dominant dark matter annihilation modes, the mass splittings among the electroweakinos, direct detection rates, and collider cross sections. The mass difference between the dark matter and the next-to-lightest neutral and charged states is typically much less than electroweak gauge boson masses. With these small mass differences, the relic neutralino surface is accessible to a future 100 TeV hadron collider, which can discover interneutralino mass splittings down to 1 GeV and thermal relic dark matter neutralino masses up to 1.5 TeV with a few inverse attobarns of luminosity. This coverage is a direct consequence of the increased collider energy: in the Standard Model events with missing transverse momentum in the TeV range have mostly hard electroweak radiation, distinct from the soft radiation shed in compressed electroweakino decays. As a result, we exploit this kinematic feature in final states including photons and leptons, tailored to the 100 TeV collider environment.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Can multistate dark matter annihilation explain the high-energy cosmic ray lepton anomalies?

Multistate dark matter (DM) models with small mass splittings and couplings to light hidden sector bosons have been proposed as an explanation for the PAMELA/Fermi/H.E.S.S. high-energy lepton excesses. We investigate this proposal over a wide range of DM density profiles, in the framework of concrete models with doublet or triplet dark matter and a hidden SU(2) gauge sector that mixes with standard model hypercharge. The gauge coupling is bounded from below by the DM relic density, and the Sommerfeld enhancement factor is explicitly computable for given values of the DM and gauge boson masses M, {mu} and the (largest) dark matter mass splitting {delta}M{sub 12}. Sommerfeld enhancement is stronger at the galactic center than near the Sun because of the radial dependence of the DM velocity profile, which strengthens the inverse Compton (IC) gamma ray constraints relative to usual assumptions. We find that the PAMELA/Fermi/H.E.S.S. lepton excesses are marginally compatible with the model predictions, and with CMB and Fermi gamma ray constraints, for M congruent with 800 GeV, {mu} < or approx. 200 MeV, and a dark matter profile with noncuspy Einasto parameters {alpha} > or approx. 0.20, r{sub s{approx}}30 kpc. We also find that the annihilating DM must provide only a subdominant (< or approx. 0.4) component of the total DM mass density, since otherwise the boost factor due to Sommerfeld enhancement is too large.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Affleck-Dine cogenesis of baryon and dark matter

We propose a mechanism for cogenesis of baryon and dark matter (DM) in the universe via the Affleck-Dine (AD) route. An AD field which breaks the lepton number symmetry, leads to the generation of lepton asymmetry by virtue of its cosmic evolution, which then gets transferred into lepton and dark sectors. While the lepton asymmetry gets converted into baryon asymmetry via sphalerons, the dark sector asymmetry leads to the final DM abundance with the symmetric part being annihilated away due to resonantly enhanced annihilation, which we choose to be provided by a gauged B – L portal. Stringent constraints from DM direct detection forces DM and B – L gauge boson masses to be light, in the few GeV ballpark. While a large portion of the model parameter space is already ruled out, the remaining parameter space is within sensitivity of laboratory as well as cosmology based experiments. The AD field also plays the role of inflaton with the required dynamics by virtue of its non-minimal coupling to gravity, consistent with observations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Warm dark matter in low scale left-right theory

We investigate the viability of having dark matter in the minimal left-right symmetric theory. We find the lightest right-handed neutrino with a mass around keV as the only viable candidate consistent with a TeV scale of left-right symmetry. In order to account for the correct relic density with such low scales, the thermal overproduction of the dark matter in the early universe is compensated by a sufficient late entropy production due to late decay of heavier right-handed neutrinos. We point out that the presence of the right-handed charge-current interactions, operative around the QCD phase transition, has a crucial impact on the amount of dilution, as does the nature of the phase transition itself. A careful numerical study, employing the Boltzmann equations, reveals the existence of a narrow window for the right-handed gauge boson mass, possibly within the reach of LHC (in disagreement with a previous study). We also elaborate on a variety of astrophysical, cosmological and low energy constraints on this scenario.

79 ASTRONOMY AND ASTROPHYSICS↗