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Dimitri V. Nanopoulos

Publications and source records attributed to Dimitri V. Nanopoulos.

At least 109 records · Page 6Linked to original sources
arXiv2012

Chanel No5 (fb^-1): The Sweet Fragrance of SUSY

We present compounding evidence of supersymmetry (SUSY) production at the LHC, in the form of correlations between the nominal 5\fb ATLAS and CMS results for the 7 TeV 2011 run and detailed Monte Carlo collider-detector simulation of a concrete supersymmetric model named No-Scale F-SU(5). Restricting analysis to those event selections which yield a signal significance S/sqrt(B+1) greater than 2, we find by application of the χ^2 statistic that strong correlations exist among the individual search strategies and also between the current best fit to the SUSY mass scale and that achieved using historical 1\fb data sets. Coupled with an appropriately large increase in the "depth" of the χ^2 well with increasing luminosity, we suggest that these features indicate the presence of a non-random structure to the data - a light fragrance perhaps evocative of some fuller coming fruition. Those searches having signal significances below 2 are assembled into a lower exclusion bound on the gaugino mass, which is shown to be consistent with the prior best fit. Assuming the forthcoming delivery of an additional tranche of integrated luminosity at 8 TeV during 2012 that measures on the order 15\fb, we project a sufficiency of actionable data to conclusively judge the merits of our proposal.

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arXiv2012

Unification of Dynamical Determination and Bare Minimal Phenomenological Constraints in No-Scale F-SU(5)

We revisit the construction of the viable parameter space of No-Scale F-SU(5), a model built on the F-lipped SU(5)xU(1)_X gauge group, supplemented by a pair of F-theory derived vector-like multiplets at the TeV scale, and the dynamically established boundary conditions of No-Scale Supergravity. Employing an updated numerical algorithm and a substantially upgraded computational engine, we significantly enhance the scope, detail and accuracy of our prior study. We sequentially apply a set of "bare-minimal" phenomenological constraints, consisting of i) the dynamically established boundary conditions of No-Scale Supergravity, ii) consistent radiative electroweak symmetry breaking, iii) precision LEP constraints on the light supersymmetric mass content, iv) the world average top-quark mass, and v) a light neutralino satisfying the 7-year WMAP cold dark matter relic density measurement. The overlap of the viable parameter space with key rare-process limits on the branching ratio for b to s gamma and the muon anomalous magnetic moment is identified as the "golden strip" of F-SU(5). A cross check for top-down theoretical consistency is provided by application of the "Super No-Scale" condition, which dynamically selects a pair of undetermined model parameters in a manner that is virtually identical to the corresponding phenomenological (driven primarily by the relic density) selection. The predicted vector-like particles are candidates for production at the future LHC, which is furthermore sensitive to a distinctive signal of ultra-high multiplicity hadronic jets. The lightest CP-even Higgs boson mass is predicted to be 120+3.5-1 GeV, with an additional 3-4 GeV upward shift possible from radiative loops in the vector-like multiplets. The predominantly bino flavored lightest neutralino is suitable for direct detection by the Xenon collaboration.

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arXiv2012

A Two-Tiered Correlation of Dark Matter with Missing Transverse Energy: Reconstructing the Lightest Supersymmetric Particle Mass at the LHC

We suggest that non-trivial correlations between the dark matter particle mass and collider based probes of missing transverse energy H_T^miss may facilitate a two tiered approach to the initial discovery of supersymmetry and the subsequent reconstruction of the LSP mass at the LHC. These correlations are demonstrated via extensive Monte Carlo simulation of seventeen benchmark models, each sampled at five distinct LHC center-of-mass beam energies, spanning the parameter space of No-Scale F-SU(5).This construction is defined in turn by the union of the Flipped SU(5) Grand Unified Theory, two pairs of hypothetical TeV scale vector-like supersymmetric multiplets with origins in F-theory, and the dynamically established boundary conditions of No-Scale Supergravity. In addition, we consider a control sample comprised of a standard minimal Supergravity benchmark point. Led by a striking similarity between the H_T^miss distribution and the familiar power spectrum of a black body radiator at various temperatures, we implement a broad empirical fit of our simulation against a Poisson distribution ansatz. We advance the resulting fit as a theoretical blueprint for deducing the mass of the LSP, utilizing only the missing transverse energy in a statistical sampling of >= 9 jet events. Cumulative uncertainties central to the method subsist at a satisfactory 12-15% level. The fact that supersymmetric particle spectrum of No-Scale F-SU(5) has thrived the withering onslaught of early LHC data that is steadily decimating the Constrained Minimal Supersymmetric Standard Model and minimal Supergravity parameter spaces is a prime motivation for augmenting more conventional LSP search methodologies with the presently proposed alternative.

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arXiv2012

A Higgs Mass Shift to 125 GeV and A Multi-Jet Supersymmetry Signal: Miracle of the Flippons at the \sqrt{s} = 7 TeV LHC

We describe a model named No-Scale F-SU(5) which is simultaneously capable of explaining the dual signals emerging at the LHC of i) a 124-126 GeV Higgs boson mass m_h, and ii) tantalizing low-statistics excesses in the multi-jet data which may attributable to supersymmetry. These targets tend to be mutually exclusive in more conventional approaches. The unified mechanism responsible for both effects is the introduction of a rather unique set of vector-like multiplets at the TeV scale, dubbed flippons, which i) can elevate m_h by around 3-4 GeV via radiative loop corrections, and ii) flatten the running of the strong coupling and color-charged gaugino, resulting in a prominent collider signal from production of light gluino pairs. This well motivated theoretical framework maintains consistency with all key phenomenological constraints, and all residual parameterization freedom may in principle be fixed by a combination of the two experiments described. We project that the already collected luminosity of 5 fb^-1 may be sufficient to definitively establish the status of this model, given appropriate data selection cuts.

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arXiv2012

A Multi-Axis Best Fit to the Collider Supersymmetry Search: The Aroma of Stops and Gluinos at the \sqrt{s} = 7 TeV LHC

In Profumo di SUSY, we presented evidence that CMS&ATLAS may have already registered a handful of deftly camouflaged supersymmetry events at the LHC in the multijet channels. Here, we explore the prospect for corroboration of this suggestion from 5 additional CMS&ATLAS search strategies targeting the production of light stops & gluinos at lower jet counts, which variously depend on heavy flavor tagging and the inclusion or exclusion of associated leptons. The current operating phase of the 7TeV LHC is highly conducive to the production of gluinos & light stops, given the supersymmetric particle mass hierarchy M_t_1<M_g<M_q that naturally evolves from the dynamics of the model named No-Scale FSU5 that we presently study. Moreover, some tension persists against the SM data-driven and MC generated background predictions in certain LHC searches of this variety. We demonstrate that the 1-sigma overlap of the allowed supersymmetric event production for these seven search methodologies roundly envelops the most favorable phenomenological subspace of FSU5, while handily generating a 125GeV Higgs boson mass. In order to test the statistical significance of any correlations across the simulated FSU5 collider response in these seven search strategies, we implement a multi-axis chi^2 fitting procedure, yielding a best overall match in the vicinity of M1/2=610GeV, corresponding to light stop & gluino masses of approximately 665GeV and 830GeV. Consequently, we suggest that FSU5 is a better global fit to the studied LHC data than the SM alone, and moreover that its predictions appear to be meaningfully correlated with observed low-statistics excesses across a wide variety of specialized search strategies. We suspect the already collected 5/fb will be sufficient to either condense or disperse the delicate aroma of stops and gluinos that suffuses the early search.

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arXiv2012

Prospects for Discovery of Supersymmetric No-Scale F-SU(5) at The Once and Future LHC

We present the reach of the Large Hadron Collider (LHC) into the parameter space of No-Scale F-SU(5), starting our analysis with the current operating energy of \sqrt{s} = 7 TeV, and extending it on through the bright future of a 14 TeV beam. No-Scale F-SU(5) is a model defined by the confluence of the F-lipped SU(5) Grand Unified Theory, two pairs of hypothetical TeV scale vector-like supersymmetric multiplets with origins in F-theory, and the dynamically established boundary conditions of No-Scale Supergravity. When searching for a five standard deviation signal, we find that the CMS experiment at the \sqrt{s} = 7 TeV LHC began to penetrate the phenomenologically viable parameter space of this model at just under 1/fb of integrated luminosity, and that the majority of this space remains intact, subsequent to analyses of the first 1.1/fb of CMS data. On the contrary, the ATLAS experiment had not reached the F-SU(5) parameter space in its first 1.34/fb of luminosity. Since the CMS and ATLAS detectors have now each amassed a milestone of 5/fb of collected luminosity, the current LHC is presently effectively probing No-Scale F-SU(5). Upon the crossing of the 5/fb threshold, the 7 TeV LHC will have achieved five standard deviation discoverability for a unified gaugino mass of up to about 532 GeV, a light stop of 577 GeV, a gluino of 728 GeV, and heavy squarks of just over 1 TeV. Extending the analysis to include a future LHC center-of-mass beam energy of \sqrt{s} = 14 TeV, the full model space of No-Scale F-SU(5) should be visible to CMS at about 30/fb of integrated luminosity. We stress that the F-SU(5) discoverability thresholds discussed here are contingent upon retaining only those events with nine jets or more for the CMS experiment and seven jets or more for the ATLAS experiment.

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arXiv2012

A Historical Profile of the Higgs Boson

The Higgs boson was postulated in 1964, and phenomenological studies of its possible production and decays started in the early 1970s, followed by studies of its possible production in e+ e-, pbar p and pp collisions, in particular. Until recently, the most sensitive searches for the Higgs boson were at LEP between 1989 and 2000, which have been complemented by searches at the Fermilab Tevatron. The LHC has recently entered the hunt, excluding a Higgs boson over a large range of masses and revealing a tantalizing hint in the range 119 to 125 GeV, and there are good prospects that the existence or otherwise of the Higgs boson will soon be established. One of the most attractive possibilities is that the Higgs boson is accompanied by supersymmetry, though composite options have yet to be excluded. This article reviews some of the key historical developments in Higgs physics over the past half-century.

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arXiv2012

Constraints on Neutrino Velocities Revisited

With a minimally modified dispersion relation for neutrinos, we reconsider the constraints on superluminal neutrino velocities from bremsstrahlung effects in the laboratory frame. Employing both the direct calculation approach and the virtual Z-boson approach, we obtain the generic decay width and energy loss rate of a superluminal neutrino with general energy. The Cohen-Glashow's analytical results for neutrinos with a relatively low energy are confirmed in both approaches. We employ the survival probability instead of the terminal energy to assess whether a neutrino with a given energy is observable or not in the OPERA experiment. Moreover, using our general results we perform systematical analyses on the constraints arising from the Super-Kamiokande and IceCube experiments.

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arXiv2012

Natural Predictions for the Higgs Boson Mass and Supersymmetric Contributions to Rare Processes

In the context of No-Scale F-SU(5), a model defined by the convergence of the F-lipped SU(5) Grand Unified Theory, two pairs of hypothetical TeV scale vector-like supersymmetric multiplets with origins in F-theory, and the dynamically established boundary conditions of No-Scale Supergravity, we predict that the lightest CP-even Higgs boson mass lies within the range of 119.0 GeV to 123.5 GeV, exclusive of the vector-like particle contribution to the mass. With reports by the CMS, ATLAS, CDF, and D0 Collaborations detailing enticing statistical excesses in the vicinity of 120 GeV in searches for the Standard Model Higgs boson, all signs point to an imminent discovery. While basic supersymmetric constructions such as mSUGRA and the CMSSM have already suffered overwhelming reductions in viable parameterization during the LHC's initial year of operation, about 80% of the original No-Scale F-SU(5) model space remains viable after analysis of the first 1.1 fb^{-1} of integrated luminosity. This model is moreover capable of handily explaining the small excesses recently reported in the CMS multijet supersymmetry search, and also features a highly favorable "golden" subspace which may simultaneously account for the key rare process limits on the muon anomalous magnetic moment (g - 2) and the branching ratio of the flavor-changing neutral current decay b to sγ. In addition, the isolated mass parameter responsible for the global particle mass normalization, the gaugino boundary mass M_{1/2}, is dynamically determined at a secondary local minimization of the minimum of the Higgs potential V_{min}, in a manner which is deeply consistent with all precision measurements at the physical electroweak scale.

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arXiv2012

Blueprints of the No-Scale Multiverse at the LHC

We present a contemporary perspective on the String Landscape and the Multiverse of plausible string, M- and F-theory vacua. In contrast to traditional statistical classifications and capitulation to the anthropic principle, we seek only to demonstrate the existence of a non-zero probability for a universe matching our own observed physics within the solution ensemble. We argue for the importance of No-Scale Supergravity as an essential common underpinning for the spontaneous emergence of a cosmologically flat universe from the quantum "nothingness". Concretely, we continue to probe the phenomenology of a specific model which is testable at the LHC and Tevatron. Dubbed No-Scale F-SU(5), it represents the intersection of the Flipped SU(5) Grand Unified Theory (GUT) with extra TeV-Scale vector-like multiplets derived out of F-theory, and the dynamics of No-Scale Supergravity, which in turn imply a very restricted set of high energy boundary conditions. By secondarily minimizing the minimum of the scalar Higgs potential, we dynamically determine the ratio tan β\simeq 15-20 of up- to down-type Higgs vacuum expectation values (VEVs), the universal gaugino boundary mass M_{1/2} \simeq 450 GeV, and consequently also the total magnitude of the GUT-scale Higgs VEVs, while constraining the low energy Standard Model gauge couplings. In particular, this local minimum minimorum lies within the previously described "golden strip", satisfying all current experimental constraints. We emphasize, however, that the overarching goal is not to establish why our own particular universe possesses any number of specific characteristics, but rather to tease out what generic principles might govern the superset of all possible universes.

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arXiv2011

Profumo di SUSY: Suggestive Correlations in the ATLAS and CMS High Jet Multiplicity Data

We present persistently amassing evidence that the CMS and ATLAS Collaborations may indeed be already registering supersymmetry events at the Large Hadron Collider (LHC). Our analysis is performed in the context of a highly phenomenologically favorable model named No-Scale F-SU(5), which represents the unification of the F-lipped SU(5) Grand Unified Theory (GUT), two pairs of hypothetical TeV-scale vector-like supersymmetric multiplets derived out of F-Theory, and the dynamically established boundary conditions of No-Scale supergravity. We document highly suggestive correlations between the first inverse femtobarn of observations by CMS and ATLAS, where seductive excesses in multijet events, particularly those with nine or more jets, are unambiguously accounted for by a precision Monte-Carlo simulation of the F-SU(5) model space. This intimate correspondence is optimized by a unified gaugino mass in the neighborhood of M_{1/2}=518 GeV. We supplement this analysis by extrapolating for the expected data profile to be realized with five inverse femtobarns of integrated luminosity, as expected to be observed at the LHC by the conclusion of 2011. Significantly, we find that this luminosity may be sufficient to constitute a SUSY discovery for the favored benchmark spectrum. Indeed, the winds wafting our way from Geneva may already be heavy with the delicate perfume of Supersymmetry.

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arXiv2011

The F-Landscape: Dynamically Determining the Multiverse

We evolve our Multiverse Blueprints to characterize our local neighborhood of the String Landscape and the Multiverse of plausible string, M- and F-theory vacua. Building upon the tripodal foundations of i) the Flipped SU(5) Grand Unified Theory (GUT), ii) extra TeV-Scale vector-like multiplets derived out of F-theory, and iii) the dynamics of No-Scale Supergravity, together dubbed No-Scale F-SU(5), we demonstrate the existence of a continuous family of solutions which might adeptly describe the dynamics of distinctive universes. This Multiverse landscape of F-SU(5) solutions, which we shall refer to as the F-Landscape, accommodates a subset of universes compatible with the presently known experimental uncertainties of our own universe. We show that by secondarily minimizing the minimum of the scalar Higgs potential of each solution within the F-Landscape, a continuous hypervolume of distinct minimum minimorum can be engineered which comprise a regional dominion of universes, with our own universe cast as the bellwether. We conjecture that an experimental signal at the LHC of the No-Scale F-SU(5) framework's applicability to our own universe might sensibly be extrapolated as corroborating evidence for the role of string, M- and F-theory as a master theory of the Multiverse, with No-Scale supergravity as a crucial and pervasive reinforcing structure.

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arXiv2011

Background Dependent Lorentz Violation from String Theory

We revisit Lorentz violation in the Type IIB string theory with D3-branes and D7-branes. We study the relativistic particle velocities in details, and show that there exist both subluminal and superluminal particle propagations. In particular, the additional contributions to the particle velosity δv\equiv (v-c)/c from string theory is proportional to both the particle energy and the D3-brane number density, and is inversely proportional to the string scale. Thus, we can realize the background dependent Lorentz violation naturally by varying the D3-brane number density in space time. To explain the superluminal neutrino propagations in the OPERA and MINOS experiments, the string scale should be around 10^5 GeV. With very tiny D3-brane number density on the interstellar scale, we can also explain the time delays for the high energy photons compared to the low energy photons in the MAGIC, HESS, and FERMI experiments simultaneously. Interestingly, we can automatically satisfy all the stringent constraints from the synchrotron radiation of the Crab Nebula, the SN1987a observations on neutrinos, and the cosmic ray experiments on charged leptons. We also address the possible phenomenological challenges to our models from the relevant experiments done on the Earth.

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arXiv2011

Background Dependent Lorentz Violation: Natural Solutions to the Theoretical Challenges of the OPERA Experiment

To explain both the OPERA experiment and all the known phenomenological constraints/observations on Lorentz violation, the Background Dependent Lorentz Violation (BDLV) has been proposed. We study the BDLV in a model independent way, and conjecture that there may exist a "Dream Special Relativity Theory", where all the Standard Model (SM) particles can be subluminal due to the background effects. Assuming that the Lorentz violation on the Earth is much larger than those on the interstellar scale, we automatically escape all the astrophysical constraints on Lorentz violation. For the BDLV from the effective field theory, we present a simple model and discuss the possible solutions to the theoretical challenges of the OPERA experiment such as the Bremsstrahlung effects for muon neutrinos and the pion decays. Also, we address the Lorentz violation constraints from the LEP and KamLAMD experiments. For the BDLV from the Type IIB string theory with D3-branes and D7-branes, we point out that the D3-branes are flavour blind, and all the SM particles are the conventional particles as in the traditional SM when they do not interact with the D3-branes. Thus, we not only can naturally avoid all the known phenomenological constraints on Lorentz violation, but also can naturally explain all the theoretical challenges. Interestingly, the energy dependent photon velocities may be tested at the experiments.

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arXiv2011

General Gauge and Anomaly Mediated Supersymmetry Breaking in Grand Unified Theories with Vector-Like Particles

In Grand Unified Theories (GUTs) from orbifold and various string constructions the generic vector-like particles do not need to form complete SU(5) or SO(10) representations. To realize them concretely, we present orbifold SU(5) models, orbifold SO(10) models where the gauge symmetry can be broken down to flipped SU(5) X U(1)_X or Pati-Salam SU(4)_C X SU(2)_L X SU(2)_R gauge symmetries, and F-theory SU(5) models. Interestingly, these vector-like particles can be at the TeV-scale so that the lightest CP-even Higgs boson mass can be lifted, or play the messenger fields in the Gauge Mediated Supersymmetry Breaking (GMSB). Considering GMSB, ultraviolet insensitive Anomaly Mediated Supersymmetry Breaking (AMSB), and the deflected AMSB, we study the general gaugino mass relations and their indices, which are valid from the GUT scale to the electroweak scale at one loop, in the SU(5) models, the flipped SU(5) X U(1)_X models, and the Pati-Salam SU(4)_C X SU(2)_L X SU(2)_R models. In the deflected AMSB, we also define the new indices for the gaugino mass relations, and calculate them as well. Using these gaugino mass relations and their indices, we may probe the messenger fields at intermediate scale in the GMSB and deflected AMSB, determine the supersymmetry breaking mediation mechanisms, and distinguish the four-dimensional GUTs, orbifold GUTs, and F-theory GUTs.

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arXiv2011

The Lightest CP-Even Higgs Boson Mass in the Testable Flipped SU(5) x U(1)_X Models from F-Theory

We study the lightest CP-even Higgs boson mass in five kinds of testable flipped SU(5) x U(1)_X models from F-theory. Two kinds of models have vector-like particles around the TeV scale, while the other three kinds also have the vector-like particles at the intermediate scale that can be considered as messenger fields in gauge mediated supersymmetry breaking. We require that the Yukawa couplings for the TeV-scale vector-like particles and the third family of the Standard Model (SM) fermions are smaller than three from the electroweak scale to the SU(3)_C x SU(2)_L unification scale. With the two-loop renormalization group equation running for the gauge couplings and Yukawa couplings, we obtain the maximal Yukawa couplings between the TeV-scale vector-like particles and Higgs fields. To calculate the lightest CP-even Higgs boson mass upper bounds, we employ the renormalization group improved effective Higgs potential approach, and consider the two-loop leading contributions in the supersymmetric SM and one-loop contributions from the TeV-scale vector-like particles. We assume maximal mixings between the stops and between the TeV-scale vector-like scalars. The numerical results for these five kinds of models are roughly the same. In particular, we show that the lightest CP-even Higgs boson can have mass up to 146 GeV naturally, which is the current upper bound from the CMS and ATLAS collaborations.

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arXiv2011

Super No-Scale F-SU(5): A Dynamic Determination of M_{1/2} and tan beta

We study the Higgs potential in No-Scale F-SU(5), a model built on the tripodal foundations of the Flipped SU(5) x U(1)_X Grand Unified Theory, extra F-theory derived TeV scale vector-like particle multiplets, and the high scale boundary conditions of No-Scale Supergravity. V_min, the minimum of the potential following radiative electroweak symmetry breaking, is a function at fixed Z-Boson mass of the universal gaugino boundary mass M_{1/2} and tanβ, the ratio of Higgs vacuum expectation values. The No-Scale nullification of the bilinear Higgs soft term B_mu at the boundary reduces V_min(M_{1/2}) to a one dimensional dependency, which may be secondarily minimized. This "Super No-Scale" condition dynamically fixes tan beta and M_{1/2} at the local minimum minimorum of V_min. Fantastically, the walls of this theoretically established secondary potential coalesce in descent to a striking concurrency with the previously phenomenologically favored "golden point" and "golden strip".

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