Vernon Barger
Flavor hierarchies are organized by a single parameter $B\simeq 5.357$ in a single-flavon Froggatt--Nielsen (FN) framework, in which each effective Yukawa entry arises from the sum of \emph{three} unit-magnitude messenger chains. We present benchmark complex $O(1)$ Yukawa matrices that reproduce quark and charged-lepton masses at $M_Z$ as powers of $ε\equiv 1/B$. The organizing principle is a two-over-two (2/2) lattice of quadrilateral mass ratios, which maps directly to a rational lattice of FN exponents. Sequential dominance preserves the leading-power exponent matrices, while subleading messenger chains generate entry-dependent complex $O(1)$ coefficients and provide a UV-friendly origin for CP violation. Neutrino masses are discussed at the level of eigenvalues within the same $B^n$ counting.
Vernon Barger
We extend the single-flavon $B$-lattice Froggatt-Nielsen (FN) framework -- previously successful for quark masses and Cabibbo-Kobayashi-Maskawa (CKM) mixing -- to the lepton sector. The same $B$-lattice power structure ($ε\equiv 1/B\simeq 0.19$) generates charged-lepton mass hierarchies and a normal-ordered neutrino spectrum; large neutrino mixing angles require an additional approximate mu-tau symmetry, broken at $\mathcal{O}(ε)$ to generate a nonzero reactor angle and CP-violating phase. The Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix factorizes as $U_{\rm PMNS}=U_e^\dagger U_ν$, with near-tribimaximal $U_ν$ corrected by small charged-lepton rotations whose phases are naturally aligned by the single-flavon origin of the Yukawa textures. This alignment produces a two-branch prediction in the $(θ_{23},δ)$ plane: a lower-octant solution with $θ_{23}\approx 43^\circ$, $δ\approx 286^\circ$, and an upper-octant solution with $θ_{23}\approx 46^\circ$, $δ\approx 304^\circ$. The lower octant is favored by a $\sim\!4{:}1$ theoretical prior. The Jarlskog invariant $J_{\rm CP}\simeq -0.027$ is nearly branch-independent; only precision measurements of the atmospheric octant and Dirac phase at DUNE, Hyper-Kamiokande, IceCube, and JUNO can distinguish the two solutions.
Vernon Barger
We present Unified Flavor (UF), a framework that synthesizes the $B$-lattice flavor hierarchy with a dynamical realization based on TeV-scale vectorlike fermion (VLF) chains. Hierarchical Yukawa couplings arise from discrete ninths-quantized lattice exponents enforced by a single flavon $Φ$ with $ε\equiv\langleΦ\rangle/Λ=1/B$, $B=75/14$. Effective Yukawa entries are generated as algebraic path sums along nearest-neighbor chains of vectorlike quarks (VLQs), factorizing into entry, chain-propagation, and exit amplitudes controlled by the discrete gauge charges. A multi-messenger structure -- in which each Yukawa entry receives coherent contributions from several chain configurations -- generates O(1) complex coefficients whose phases are the physical origin of CP violation. We derive a general chain-inversion theorem, perform systematic perturbative diagonalization of both up- and down-type Yukawa textures, and show that the Cabibbo--Kobayashi--Maskawa (CKM) mixing hierarchy and CP-phase structure emerge naturally from the lattice exponent algebra and multi-messenger interference. All six quark masses are reproduced with O(1) coefficients that are essentially unity. The chain locality simultaneously suppresses dangerous flavor-changing neutral currents (FCNCs) and satisfies electroweak precision constraints, while requiring VLQs with masses in the multi-TeV range accessible at the High-Luminosity Large Hadron Collider (HL-LHC). The same discrete gauge symmetry that enforces the lattice structure also protects the Peccei--Quinn axion quality, unifying flavor, CP violation, and the strong CP problem. The framework extends to the lepton sector, reproducing charged-lepton mass hierarchies, the normal-ordered neutrino spectrum, and PMNS mixing with a predictive two-branch octant--$δ$ correlation testable at DUNE and Hyper-Kamiokande.
Vernon Barger
Quark and lepton hierarchies are organized by rational powers of a single parameter in units of one ninth. We show that this ``flavor in ninths'' structure points to a discrete $\mathbb{Z}_{18}$ gauge origin of Froggatt--Nielsen symmetry, whose $\mathbb{Z}_9$ subgroup controls the flavor lattice. Identifying the flavon with the Peccei--Quinn field, the same symmetry stabilizes the QCD axion, enforces domain-wall number $N_{\rm DW}=1$, and predicts the axion--photon coupling through the anomaly ratio $E/N=8/3$ (or $2$ with light higgsinos). The lowest Planck-suppressed operator appears at dimension eighteen, naturally solving the axion quality problem. For $f_a\sim(5$--$8)\times10^{11}$ GeV the axion accounts for dark matter and lies within near-term haloscope reach.
Vernon Barger
Flavor hierarchies emerge from a single hierarchical parameter $B$ in a one-flavon Froggatt--Nielsen scheme. Fixing $B=5.357$ from charged-lepton ratios ($m_e:m_μ:m_τ\!\propto\!ε^5:ε^2:1$, $ε=1/B$), we reproduce quark masses and CKM targets at $M_Z$ with $\ordone$ coefficients. The same $ε$ gives viable lepton textures and benchmarks for $U_{\rm PMNS}$, $\sum m_ν$, and $m_{ββ}$. Compact correlations ($|V_{us}|,|V_{cb}|,|V_{ub}|,θ_{13}^{\rm PMNS}$) follow from powers of $ε$.
Vernon Barger
We present the quark weak-mixing component of a Froggatt--Nielsen program, with one flavon and three messengers, in which a single hierarchy parameter $B$ (with $ε\equiv 1/B$) and a rational-exponent ``$B$-lattice'' organize fermion Yukawa textures. Building on companion mass-fit work, we translate the lattice into sharp predictions for quark mixing. The four-magnitude parameterization serves as a practical interface between the flavon Yukawa textures and quark weak mixing observables, yielding coefficient-free ratio tests of the lattice structure.
V. Barger, J. Learned, S. Pakvasa
Jul 19, 2012·astro-ph.HE·PDF We propose an interpretation of the two neutrino initiated cascade events with PeV energies observed by IceCube: Ultra-high energy cosmic ray protons (or Fe nuclei) scatter on CMB photons through the Delta-resonance (the Berezinsky-Zatsepin process) yielding charged pions and neutrons. The neutron decays give electron-antineutrinos which undergo neutrino oscillations to populate all antineutrino flavors, but the electron-antineutrino flux remains dominant. At 6.3 PeV electron-antineutrino energy their annihilation on electrons in the IceCube detector is enhanced by the Glashow resonance (the W-boson) whose decays can give the PeV showers observed in the IceCube detector. The two observed showers with ~1 PeV energies would need to be from W leptonic decays to electrons and taus. An order of magnitude higher event rate of showers at 6.3 PeV is predicted from W to hadron decays. This interpretation can be tested in the near term. It has significant physics implications on the origin of the highest energy cosmic rays, since neutrino events and cosmic ray events likely share a common origin.
Vernon Barger, Muneyuki Ishida
The radion is expected to be the first signal of the Randall-Sundrum (RS) model. We explore the possibility of finding it in the ongoing Higgs searches at the LHC. The little RS model (LRS), which has a fundamental scale at about 1000 TeV, is excluded over wide ranges of the radion mass from the latest $WW$ and gamma gamma data by ATLAS and CMS.
Vernon Barger, Jason Kumar, Danny Marfatia, Enrico Maria Sessolo
We investigate the prospects for indirect detection of fermion WIMPless dark matter at the neutrino telescopes IceCube and DeepCore. The dark matter annihilating in the Sun is a hidden sector Majorana fermion that couples through Yukawa couplings to a connector particle and a visible sector particle, and it exhibits only spin-dependent scattering with nuclei via couplings to first generation quarks. We consider cases where the annihilation products are taus, staus, or sneutrinos of the three generations. To evaluate the muon fluxes incident at the detector, we propagate the neutrino spectra through the solar medium and to the Earth and account for the effects of neutrino oscillations, energy losses due to neutral- and charged-current interactions, and tau regeneration. We find that for the stau and sneutrino channels, a 5 yr 3$σ$ detection of dark matter lighter than about 300 GeV is possible at IceCube for large Yukawa couplings or for dark matter and connector particles with similar masses. The tau channel offers far better detection prospects. However, due to its lower energy threshold and better muon background rejection capability, DeepCore is able to detect signals in all annihilation channels and for a wider range of dark matter masses.
Vernon Barger, Cheng-Wei Chiang, Wai-Yee Keung, Danny Marfatia
A measurement of the Lamb shift in muonic hydrogen yields a charge radius of the proton that is smaller than the CODATA value by about 5 standard deviations. We explore the possibility that new scalar, pseudoscalar, vector, and tensor flavor-conserving nonuniversal interactions may be responsible for the discrepancy. We consider exotic particles that among leptons, couple preferentially to muons, and mediate an attractive nucleon-muon interaction. We find that the many constraints from low energy data disfavor new spin-0, spin-1 and spin-2 particles as an explanation.
Vernon Barger, Y. Gao, Mathew McCaskey, Gabe Shaughnessy
A light Higgs boson is preferred by $M_W$ and $m_t$ measurements. A complex scalar singlet addition to the Standard Model allows a better fit to these measurements through a new light singlet dominated state. It then predicts a light Dark Matter (DM) particle that can explain the signals of DM scattering from nuclei in the CoGeNT and DAMA/LIBRA experiments. Annihilations of this DM in the galactic halo, $AA\rightarrow b\bar{b}, c\bar{c}, τ^+τ^-$, lead to gamma rays that naturally improve a fit to the Fermi Large Area Telescope data in the central galactic regions. The associated light neutral Higgs boson may also be discovered at the Large Hadron Collider.
Vernon Barger, Pavel Fileviez Perez, Sogee Spinner
In this letter we point out that in a class of models for spontaneous R-parity breaking based on gauged B-L, the spectrum for neutrinos is quite peculiar. We find that those models generally predict three layers of neutrinos: one heavy sterile neutrino, two massive active neutrinos, and three near massless (one active and two sterile) neutrinos.
Vernon Barger, Peisi Huang, Muneyuki Ishida, Wai-Yee Keung
We constrain the masses of scalar-tops (stop) by analyzing the new precision Tevatron measurement of the W-boson mass and the LHC/Tevatron indications of a Higgs boson of mass 125.5+-1 GeV. Our study adopts Natural SUSY with low fine-tuning, which has multi-TeV first and second generation squarks and a light Higgsino mixing parameter mu=150 GeV. An effective Lagrangian calculation is made of mh to 3-loops using the H3m program with weak scale SUSY parameters obtained from RGE evolution from the GUT scale in the Natural SUSY scenario. The SUSY radiative corrections to the Higgs mass imply maximal off-diagonal elements of the stop mass-matrix and a mass splitting of the two stops larger than 400 GeV.
Vernon Barger, Wai-Yee Keung, Danny Marfatia, Po-Yan Tseng
Monojet and monophoton final states with large missing transverse energy (${\not E}_T$) are important for dark matter (DM) searches at colliders. We present analytic expressions for the differential cross sections for the parton-level processes, $q\bar{q}(qg)\to g(q)χ\barχ$ and $q\bar{q}\to γχ\barχ$, for a neutral DM particle with a magnetic dipole moment (MDM) or an electric dipole moment (EDM). We collectively call such DM candidates dipole moment dark matter (DMDM). We also provide monojet cross sections for scalar, vector and axial-vector interactions. We then use ATLAS/CMS monojet${+\not E}_T$ data and CMS monophoton$+{\not E}_T$ data to constrain DMDM. We find that 7 TeV LHC bounds on the MDM DM-proton scattering cross section are about six orders of magnitude weaker than on the conventional spin-independent cross section.
Vernon Barger, Danny Marfatia, Andrea Peterson
We customize the simulation code FEWZ (Fully Exclusive W, Z Production) to study Z' production at the LHC for both \sqrt{s}=8 TeV and 14 TeV. Using the results of our simulation for several standard benchmark Z' models, we derive a semi-empirical expression for the differential cross section, that permits the determination of Z' couplings in a model-independent manner. We evaluate cross sections and other observables for large classes of models, including the common E_6, left-right and B-L models, as a function of model parameters. We also consider a hidden sector Z' that couples to standard model fermions via kinetic and mass mixing and serves as a mediator of isospin-violating interactions with dark matter. We combine the results of LHC Z' searches and dark matter direct detection experiments with global electroweak data to obtain mass-dependent constraints on the model parameters.
Howard Baer, Vernon Barger, Peisi Huang, Dan Mickelson, Azar Mustafayev, Xerxes Tata
The recent discovery of a 125 GeV Higgs-like resonance at LHC, coupled with the lack of evidence for weak scale supersymmetry (SUSY), have severely constrained SUSY models such as mSUGRA/CMSSM. As LHC probes deeper into SUSY model parameter space, the little hierarchy problem -- how to reconcile the Z and Higgs boson mass scale with the scale of SUSY breaking -- will become increasingly exacerbated unless a sparticle signal is found. We evaluate two different measures of fine-tuning in the mSUGRA/CMSSM model. The more stringent of these, Δ_{HS}, includes effects that arise from the high scale origin of the mSUGRA parameters while the second measure, Δ_{EW}, is determined only by weak scale parameters: hence, it is universal to any model with the same particle spectrum and couplings. Our results incorporate the latest constraints from LHC7 sparticle searches, LHCb limits from B_s ->μ^+μ^- and also require a light Higgs scalar with m_h ~123-127 GeV. We present fine-tuning contours in the m_0 vs. m_{1/2} plane for several sets of A_0 and tan(β) values. We also present results for Δ_{HS} and Δ_{EW} from a scan over the entire viable model parameter space. We find a Δ_{HS} > 10^3, or at best 0.1% fine-tuning. For the less stringent electroweak fine tuning, we find Δ_{EW} > 10^2, or at best 1% fine-tuning. Two benchmark points are presented that have the lowest values of Δ_{HS} and Δ_{EW}. Our results provide a quantitative measure for ascertaining whether or not the remaining mSUGRA/CMSSM model parameter space is excessively fine-tuned, and so could provide impetus for considering alternative SUSY models.
Vernon Barger, Muneyuki Ishida, Wai-Yee Keung
A number of candidate theories beyond the standard model (SM) predict new scalar bosons below the TeV region. Among these, the radion, which is predicted in the Randall-Sundrum model, and the dilaton, which is predicted in spontaneous scale symmetry breaking, have very similar couplings to those of the SM Higgs boson, and it is very difficult to differentiate these three spin-0 particles in the expected signals of the Higgs boson at the LHC and Tevatron. We demonstrate that the observation of the ratio sigma(gamma gamma)/sigma(WW) gives a simple and decisive way, independently of the values of model parameters: the VEVs of the radion and dilaton fields.
Vernon Barger, Wai-Yee Keung, Chiu-Tien Yu
Recent results from the CDF Collaboration indicate the the top-pair forward-backward asymmetry is largest in regions of high rapidity difference $|Δy|$ and invariant mass $M_{t\bar t}.$ We show that experimental observations can be explained by our previously proposed Asymmetric Left-Right Model (ALRM). The gauge symmetry $U'(1)\times SU'(2)\times SU(2)$ is broken by a triplet Higgs in the primed sector. The $W'$ boson has a $(t,d)$ right-handed coupling and the $Z'$ boson has diagonal fermion couplings. We determine the model parameters to be $M_{W'} = 700$ GeV, $M_{Z'}=1$ TeV, and charged current coupling $g'_2=3$. The $W'$ and $Z'$ total decay widths are of $\mathcal{O}(100$ GeV). The signals from $Z'\to t\bar t$ and $W'\to tb$ at the LHC will test the model.
Howard Baer, Vernon Barger, Dakotah Martinez
Supersymmetric models with a strongly interacting superconformal hidden sector (HS) may drive soft SUSY breaking scalar masses, bilinear soft term Bμand Higgs combinations m_{H_{u,d}}^2+μ^2 to small values at some intermediate scale, leading to unique sparticle mass spectra along with possibly diminished finetuning in spite of a large superpotential $μ$ parameter. We set up a computer code to calculate such spectra, which are then susceptible to a variety of constraints: 1. possible charge-or-color breaking (CCB) minima in the scalar potential, 2. unbounded from below (UFB) scalar potential, 3. improper electroweak symmetry breaking, 4. a charged or sneutrino lightest SUSY particle (LSP), 5. generating m_h~ 125 GeV, 6. consistency with LHC sparticle mass limits, and 7. naturalness. We find this bevy of constraints leaves little or no viable parameter space for the case where hidden sector dynamics dominates MSSM running, even for the case of non-universal gaugino masses. For the case with moderate HS running with comparable MSSM running, and with universal gaugino masses, then the finetuning is ameliorated, but nonetheless remains high. Viable spectra with moderate HS running and with low finetuning and large mu can be found for non-universal gaugino masses.
Howard Baer, Vernon Barger, Xerxes Tata, Kairui Zhang
In natural supersymmetric models defined by no worse than a part in thirty electroweak fine-tuning, winos and binos are generically expected to be much heavier than higgsinos. Moreover, the splitting between the higgsinos is expected to be small, so that the visible decay products of the heavier higgsinos are soft, rendering the higgsinos quasi-invisible at the LHC. Within the natural SUSY framwork, heavy electroweak gauginos decay to W, Z or h bosons plus higgsinos in the ratio ~2:1:1, respectively. This is in sharp contrast to models with a bino-like lightest superpartner and very heavy higgsinos, where the charged (neutral) wino essentially always decays to a W (h) boson and an invisible bino. Wino pair production at the LHC, in natural SUSY, thus leads to VV, Vh and hh+MET final states (V=W, Z) where, for TeV scale winos, the vector bosons and h daughters are considerably boosted. We identify eight different channels arising from the leptonic and hadronic decays of the vector bosons and the decay h-> b\bar{b}, each of which offers an avenue for wino discovery at the high luminosity LHC (HL-LHC). By combining the signal in all eight channels we find, assuming \sqrt{s}=14 TeV and an integrated luminosity of 3000 fb^{-1}, that the discovery reach for winos extends to m(wino)~1.1~TeV, while the 95% CL exclusion range extends to a wino mass of almost 1.4~TeV. We also identify ``higgsino specific channels'' which could serve to provide 3σevidence that winos lighter than 1.2~TeV decay to light higgsinos rather than to a bino-like LSP, should a wino signal appear at the HL-LHC.