Grand Unified Theory ≈ Grand Unified Theory
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Solving the Hierarchy Problem at Reheating with a Large Number of Degrees of Freedom Open
We present a new solution to the electroweak hierarchy problem. We introduce N copies of the standard model with varying values of the Higgs mass parameter. This generically yields a sector whose weak scale is parametrically removed from t…
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Baryogenesis from the weak scale to the grand unification scale Open
The current status of baryogenesis is reviewed, with an emphasis on electroweak baryogenesis and leptogenesis. The first detailed studies were carried out for SU(5) grand unified theory (GUT) models where CP-violating decays of leptoquarks…
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Testing the Seesaw Mechanism and Leptogenesis with Gravitational Waves Open
We present the possibility that the seesaw mechanism with thermal leptogenesis can be tested using the stochastic gravitational background. Achieving neutrino masses consistent with atmospheric and solar neutrino data, while avoiding non-p…
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Left-right SU(4) vector leptoquark model for flavor anomalies Open
Building on our recent proposal to explain the experimental hints of new\nphysics in $B$ meson decays within the framework of Pati-Salam quark-lepton\nunification, through the interactions of the $(3,1)_{2/3}$ vector leptoquark,\nwe constr…
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Dark matter and gauge coupling unification in nonsupersymmetric SO(10) grand unified models Open
Unlike minimal SU(5), SO(10) provides a straightforward path towards gauge coupling unification by modifying the renormalization group evolution of the gauge couplings above some intermediate scale which may also be related to the seesaw m…
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Towards a complete A4 × SU(5) SUSY GUT Open
We propose a renormalisable model based on A4 family symmetry with an SU(5) grand unified theory (GUT) which leads to the minimal supersymmetric standard model (MSSM) with a ℤ9 × ℤ6 symmetry provides the fermion mass hierarchy in both the …
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Interpretation of the diphoton excess at CMS and ATLAS Open
We consider the diphoton resonance at the 13 TeV LHC in a consistent model with new scalars and vector-like fermions added to the Standard Model (SM), which can be constructed from orbifold grand unified theories and string models. The gau…
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750 GeV diphotons from a D3-brane Open
Motivated by the recently reported diphoton excess at 750 GeV observed by\nboth CMS and ATLAS, we study string-based particle physics models which can\naccommodate this signal. Quite remarkably, although Grand Unified Theories in\nF-theory…
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The F-theory geometry with most flux vacua Open
Applying the Ashok-Denef-Douglas estimation method to elliptic Calabi-Yau fourfolds suggests that a single elliptic fourfold Mmax gives rise to O(10272,000) F-theory flux vacua, and that the sum total of the numbers of flux vacua from all …
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The Orbifold Higgs Open
We introduce and systematically study an expansive class of “orbifold Higgs” theories in which the weak scale is protected by accidental symmetries arising from the orbifold reduction of continuous symmetries. The protection mechanism elim…
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Singling out SO(10) GUT models using recent PTA results Open
In this work, we construct promising model-building routes towards SO(10) grand unified theory inflation and examine their ability to explain the recent pulsar timing arrays (PTAs) results hinting at a stochastic gravitational wave (GW) ba…
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Leptogenesis via Axion Oscillations after Inflation Open
Once a light axionlike scalar field couples to the electroweak gauge bosons, its classical motion during reheating induces an effective chemical potential for the fermion number. In the presence of rapid lepton number (L)-violating process…
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Fundamental partial compositeness Open
We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model…
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SU(5) unification with TeV-scale leptoquarks Open
It has previously been noted that SU(5) unification can be achieved via the simple addition of light scalar leptoquarks from two split 10 multiplets. We explore the parameter space of this model in detail and find that unification requires…
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Unification, proton decay, and topological defects in non-SUSY GUTs with thresholds Open
We calculate the proton lifetime and discuss topological defects in a wide class of non-supersymmetric (non-SUSY) SO(10) and E(6) grand unified theories (GUTs), broken via left-right subgroups with one or two intermediate scales (a total o…
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Gauge-Higgs grand unification Open
$SO(11)$ gauge-Higgs grand unification in the Randall-Sundrum warped space is\nproposed. Orbifold boundary conditions and one brane scalar field reduce\n$SO(11)$ to the standard model symmetry, which is further broken to $SU(3)_C\n\\times …
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Toward realistic gauge–Higgs grand unification Open
The SO(11) gauge–Higgs grand unification in the Randall–Sundrum warped space is presented. The 4D Higgs field is identified as the zero mode of the fifth-dimensional component of the gauge potentials, or as the fluctuation mode of the Ahar…
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Metastable cosmic strings Open
Many symmetry breaking patterns in grand unified theories (GUTs) give rise to cosmic strings that eventually decay when pairs of GUT monopoles spontaneously nucleate along the string cores. These strings are known as metastable cosmic stri…
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Diphoton resonance from a new strong force Open
We explore a "partial unification" model that could explain the diphoton event excess around $750 \, \rm GeV$ recently reported by the LHC experiments. A new strong gauge group is combined with the ordinary color and hypercharge gauge grou…
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Asymptotically safe grand unification Open
Phenomenologically appealing supersymmetric grand unified theories have large gauge representations and thus are not asymptotically free. Their ultraviolet validity is limited by the appearance of a Landau pole well before the Planck scale…
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Leptogenesis in minimal predictive seesaw models Open
We estimate the Baryon Asymmetry of the Universe (BAU) arising from leptogenesis within a class of minimal predictive seesaw models involving two right-handed neutrinos and simple Yukawa structures with one texture zero. The two right-hand…
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Axion Isocurvature and Magnetic Monopoles Open
We propose a simple mechanism to suppress axion isocurvature fluctuations using hidden sector magnetic monopoles. This allows for the Peccei-Quinn scale to be of the order of the unification scale consistently with high scale inflation.
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Small neutrino masses and gauge coupling unification Open
The physics responsible for gauge coupling unification may also induce small neutrino masses. We propose a novel gauge-mediated radiative seesaw mechanism for calculable neutrino masses. These arise from quantum corrections mediated by new…
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Confronting SO(10) GUTs with proton decay and gravitational waves Open
Grand Unified Theories (GUT) predict proton decay as well as the formation of cosmic strings which can generate gravitational waves. We determine which non-supersymmetric SO(10) breaking chains provide gauge unification in addition to a gr…
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Improved predictions for intermediate and heavy supersymmetry in the MSSM and beyond Open
For a long time, the minimal supersymmetric standard model (MSSM) with light masses for the supersymmetric states was considered as the most natural extension of the Standard Model of particle physics. Consequently, a valid approximation w…
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Roadmap of left-right models based on GUTs Open
We perform a detailed study of the grand unified theories $SO(10)$ and $E(6)$\nwith left-right intermediate gauge symmetries of the form $SU(N)_L\\otimes\nSU(N)_R \\otimes \\mathcal{G}$. Proton decay lifetime constrains the unification\nsc…
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Siegel modular flavor group and from string theory Open
We derive the potential modular symmetries of heterotic string theory. For a\ntoroidal compactification with Wilson line modulus, we obtain the Siegel\nmodular group $\\mathrm{Sp}(4,\\mathbb{Z})$ that includes the modular symmetries\n$\\ma…
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GUT precursors and entwined SUSY: The phenomenology of stable nonsupersymmetric strings Open
Recent work has established a method of constructing nonsupersymmetric string models that are stable, with near-vanishing one-loop dilaton tadpoles and cosmological constants. This opens up the tantalizing possibility of realizing stable s…
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Eternal Higgs inflation and the cosmological constant problem Open
We investigate the Higgs potential beyond the Planck scale in the superstring theory, under the assumption that the supersymmetry is broken at the string scale. We identify the Higgs field as a massless state of the string, which is indica…
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Multi-fold Gravity-Electroweak Theory and Symmetry Breaking Open
Among all the candidates for (Grand Unification Theories) GUTs, modeling of GR and quantum gravity or understanding Loop Quantum Gravity (LQG), the use of the left-handed spin connection as variable for canonical gravity (self-dual), and t…