Browsing by Author "Minic, Djordje"

Now showing 1 - 20 of 68
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    The 750 GeV diphoton excess in unified SU(2)(L) x SU(2)(R) x SU(4) models from noncommutative geometry
    Aydemir, U.; Minic, Djordje; Sun, C.; Takeuchi, Tatsu (World Scientific, 2016-06-14)
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    Analysis of Neutral D Meson Two-Body Decays to a Neutral Kaon and a Neutral Pion
    Kimmel Jr, Taylor Douglas (Virginia Tech, 2021-09-15)
    Decays of neutral D mesons to final states containing K + π's could provide evidence for CP-violation from a source not accounted for in the Standard Model. Due to the interference between Cabibbo-favored and Cabibbo-suppressed transitions, a decay rate asymmetry of D0 → K0S π0 compared to D0 → K0Lπ0 has been predicted to be non-zero. If New Physics interferes in doubly Cabibbo-suppressed D decays, the measurement of this asymmetry would differ from the predicted value and may provide evidence for CP-violation beyond the CKM mechanism. I present an analysis method to measure this branching fraction asymmetry, R(D0) ≡ B(D0→K0S π0)−B(D0→K0L π0)/(B(D0→K0Sπ0)+B(D0→K0Lπ0)), utilizing e+e− → cc events in the Belle dataset.
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    Aspects of Supersymmetry
    Jia, Bei (Virginia Tech, 2014-04-21)
    This thesis is devoted to a discussion of various aspects of supersymmetric quantum field theories in four and two dimensions. In four dimensions, 𝒩 = 1 supersymmetric quantum gauge theories on various four-manifolds are constructed. Many of their properties, some of which are distinct to the theories on flat spacetime, are analyzed. In two dimensions, general 𝒩 = (2, 2) nonlinear sigma models on S² are constructed, both for chiral multiplets and twisted chiral multiplets. The explicit curvature coupling terms and their effects are discussed. Finally, 𝒩 = (0, 2) gauged linear sigma models with nonabelian gauge groups are analyzed. In particular, various dualities between these nonabelian gauge theories are discussed in a geometric content, based on their Higgs branch structure.
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    Autonomous Computing Systems
    Steiner, Neil Joseph (Virginia Tech, 2008-03-27)
    This work discusses autonomous computing systems, as implemented in hardware, and the properties required for such systems to function. Particular attention is placed on shifting the associated complexity into the systems themselves, and making them responsible for their own resources and operation. The resulting systems present simpler interfaces to their environments, and are able to respond to changes within themselves or their environments with little or no outside intervention. This work proposes a roadmap for the development of autonomous computing systems, and shows that their individual components can be implemented with present day technology. This work further implements a proof-of-concept demonstration system that advances the state-of-the-art. The system detects activity on connected inputs, and responds to the conditions without external assistance. It works from mapped netlists, that it dynamically parses, places, routes, configures, connects, and implements within itself, at the finest granularity available, while continuing to run. The system also models itself and its resource usage, and keeps that model synchronized with the changes that it undergoes—a critical requirement for autonomous systems. Furthermore, because the system assumes responsibility for its resources, it is able to dynamically avoid resources that have been masked out, in a manner suitable for defect tolerance.
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    B-decay anomalies and scalar leptoquarks in unified Pati-Salam models from noncommutative geometry
    Aydemir, Ufuk; Minic, Djordje; Sun, Chen; Takeuchi, Tatsu (Springer, 2018-09-19)
    Motivated by possible scalar-leptoquark explanations of the recently reported B-decay anomalies, we investigate whether the required leptoquarks can be accommodated within models based on noncommutative geometry (NCG). The models considered have the gauge structure of Pati-Salam models, SU(4) x SU(2)(L) x SU(2)(R), with gauge coupling unification at a single scale. In one of the models, we find a unique scalar leptoquark with quantum numbers (3, 1, -1/3)(321), originating from a complex multiplet (6, 1, 1)(422), which can potentially explain the B-decay anomalies if its mass is on the order of a few TeV. The unification of couplings can be realized with the inclusion of a single step of intermediate symmetry breaking. The scalar leptoquark under consideration does not contribute to proton decay due to the absence of diquark couplings, as dictated by the underlying noncommutative geometry.
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    Background independent quantum mechanics and gravity
    Minic, Djordje; Tze, C. H. (American Physical Society, 2003-09-15)
    We argue that the demand of background independence in a quantum theory of gravity calls for an extension of standard geometric quantum mechanics. We discuss a possible kinematical and dynamical generalization of the latter by way of a quantum covariance of the state space. Specifically, we apply our scheme to the problem of a background independent formulation of matrix theory.
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    Bell's Inequalities, Superquantum Correlations, and String Theory
    Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; Takeuchi, Tatsu; Tze, Chia-Hsiung (Hindawi, 2011-01-01)
    We offer an interpretation of super-quantum correlations in terms of a “doubly” quantum theory. We argue that string theory, viewed as a quantum theory with two deformation parameters, the string tension a′ and the string coupling constant gs, is such a super-quantum theory, one that transgresses the usual quantum violations of Bell’s inequalities. We also discuss the ħ ⟶ ∞ limit of quantum mechanics in this context. As a super-quantum theory, string theory should display distinct experimentally observable super-correlations of entangled stringy states.
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    Bell's Inequalities, Superquantum Correlations, and String Theory
    Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; Takeuchi, Tatsu; Tze, Chia-Hsiung (Hindawi Publishing Corporation, 2011)
    We offer an interpretation of superquantum correlations in terms of a “doubly” quantum theory.We argue that string theory, viewed as a quantum theory with two deformation parameters, the string tension α', and the string coupling constant gs, is such a superquantum theory that transgresses the usual quantum violations of Bell's inequalities. We also discuss the ℏ→∞ limit of quantum mechanics in this context. As a superquantum theory, string theory should display distinct experimentally observable supercorrelations of entangled stringy states.
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    Biorthogonal quantum mechanics: super-quantum correlations and expectation values without definite probabilities
    Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; Takeuchi, Tatsu (IOP, 2013-12-06)
    We propose mutant versions of quantum mechanics constructed on vector spaces over the finite Galois fields GF(3) and GF(9). The mutation we consider here is distinct from what we proposed in previous papers on Galois field quantum mechanics. In this new mutation, the canonical expression for expectation values is retained instead of that for probabilities. In fact, probabilities are indeterminate. Furthermore, it is shown that the mutant quantum mechanics over the finite field GF(9) exhibits super-quantum correlations (i.e. the Bell-Clauser-Horne-Shimony-Holt bound is 4). We comment on the fundamental physical importance of these results in the context of quantum gravity.
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    Bulk entropy is crucial to validate the second law of the extended black hole thermodynamics
    Dai, De-Chang; Minic, Djordje; Stojkovic, Dejan (Springer, 2021-12-17)
    The extended black hole thermodynamics in which the cosmological constant plays the role of pressure significantly enriches the phase structure of the theory. In order to understand the extended black hole thermodynamics more precisely, we let the value of the cosmological constant vary dynamically via tunneling from one vacuum to another in a black hole induced vacuum decay. In this process, entropy of the matter/energy released by a black hole is crucial to validate the second law of thermodynamics. In other words, without taking this bulk entropy into account, entropy associated with the black hole and cosmological horizons may not always increase. Since the bulk entropy is not represented by the black hole and the cosmological horizons, this result calls for a more careful interpretation of the holographic principle in which environmental effects are taken into account.
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    Classical Implications of the Minimal Length Uncertainty Relation
    Benczik, S. Z.; Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Rayyan, S.; Takeuchi, Tatsu (2002-09-12)
    We study the phenomenological implications of the classical limit of the "stringy" commutation relations [x_i,p_j]=i hbar[(1+beta p^2) delta_{ij} + beta' p_i p_j]. In particular, we investigate the "deformation" of Kepler's third law and apply our result to the rotation curves of gas and stars in spiral galaxies.
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    Constraining New Physics with Colliders and Neutrinos
    Sun, Chen (Virginia Tech, 2017-06-06)
    In this work, we examine how neutrino and collider experiments can each and together put constraints on new physics more stringently than ever. Constraints arise in three ways. First, possible new theoretical frameworks are reviewed and analyzed for the compatibility with collider experiments. We study alternate theories such as the superconnection formalism and non-commutative geometry (NCG) and show how these can be put to test, if any collider excess were to show up. In this case, we use the previous diboson and diphoton statistical excess as examples to do the analysis. Second, we parametrize low energy new physics in the neutrino sector in terms of non-standard interactions (NSI), which are constrained by past and proposed future neutrino experiments. As an example, we show the capability of resolving such NSI with the OscSNS, a detector proposed for Oak Ridge National Lab and derive interesting new constraints on NSI at very low energy (≲ 50 MeV). Apart from this, in order to better understand the NSI matter effect in long baseline experiments such as the future DUNE experiment, we derive a new compact formula to describe the effect analytically, which provides a clear physical picture of our understanding of the NSI matter effect compared to numerical computations. Last, we discuss the possibility of combining neutrino and collider data to get a better understanding of where the new physics is hidden. In particular, we study a model that produces sizable NSI to show how they can be constrained by past collider data, which covers a distinct region of the model parameter space from the DUNE experiment. In combining the two, we show that neutrino experiments are complementary to collider searches in ruling out models such as the ones that utilize a light mediator particle. More general procedures in constructing such models relevant to neutrino experiments are also described.
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    Constraints on a generalization of geometric quantum mechanics from neutrino and B0- B 0 ¯ $$ \overline{B^0} $$ oscillations
    Bhatta, Nabin; Minic, Djordje; Takeuchi, Tatsu (2024-02-05)
    Abstract Nambu Quantum Mechanics, proposed in Phys. Lett. B536, 305 (2002), is a deformation of canonical Quantum Mechanics in which the manifold over which the “phase” of an energy eigenstate time evolves is modified. This generalization affects oscillation and interference phenomena through the introduction of two deformation parameters that quantify the extent of deviation from canonical Quantum Mechanics. In this paper, we constrain these parameters utilizing atmospheric neutrino oscillation data, and B0- B 0 ¯ $$ \overline{B^0} $$ oscillation data from Belle. Surprisingly, the bound from atmospheric neutrinos is stronger than the bound from Belle. Various features of Nambu Quantum Mechanics are also discussed.
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    Constraints on New Physics from Neutrino and Other Particle Experiments
    Kao, Yee (Virginia Tech, 2010-12-07)
    In this thesis we analyze a number of past, current, and future experiments to extract information on physics beyond the Standard Model. We use the Jacobi method to derive a set of simplified expressions for the probabilities of neutrino oscillations in matter. we show the possible constraints that can be placed on various models beyond the Standard Model. In several cases, we find that the limits thus thus obtained could be competitive with those expected from direct searches at the Large Hadron Collider. We then consider the possible effects of new physics beyond the Standard Model on precision measurements. In particular, we look at recent Bell/Babar results on the B meson branching fraction, and the bounds on Tau-decays from Babar. As a general framework of analyzing new physics beyond the Standard Model, we discuss what constraints can be placed on R-parity violating SUSY from these experiments. To complete our analysis, we update the single-coupling bounds on R-parity violating supersymmetry using the most up to date data as of October 2009. In addition to the data listed in the latest Review of Particle Properties, we utilize a new measurement of the weak charge of cesium-133, and preliminary Tau-decay branching fractions from Babar. Analysis of semileptonic D-decay is improved by the inclusion of experimentally measured form-factors into the calculation of the Standard Model predictions.
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    Constraints on New Physics from Various Neutrino Experiments
    Pronin, Alexey (Virginia Tech, 2008-04-09)
    In this thesis we consider a number of past, present, and future neutrino experiments designed to test physics beyond the Standard Model. First, we analyze potential new physics explanations of the NuTeV anomaly and check their compatibility with the most recent experimental data. The models we consider are: gauged Lmu-Ltau, gauged B-3Lmu, and S1, S3, V1, V3 leptoquarks. We find that only the triplet leptoquark models can explain NuTeV and be compatible with the data from other experiments at the same time, and only if the components of the triplet have different masses. Then, we analyze the prospects of discovery of heavy Majorana neutrinos (neutrissimos) suggested by the Okamura model at the LHC. We find that these particles, if produced, will live short enough to decay inside of the detector, while long enough to lead to a narrow peak in the invariant mass spectrum of the decay products. We estimate the typical masses of the neutrissimos to be in the TeV range. However, studies exist that have shown that if their masses are larger than about 150 GeV then the production cross-section is too small to lead to an observable event rate. Thus, we conclude that it will not be possible to detect the neutrissimo at the LHC unless its mass is smaller that about 150 GeV which corresponds to a very small region close to the edge of the parameter space of the Okamura model. Nevertheless, we argue that the signature of the neutrissimo may be detectable in other neutrino experiments which may be carried out in the future. As examples, we consider the NuSOnG experiment, which is a fixed target neutrino scattering experiment proposed at Fermilab, and a hypothetical long-baseline neutrino oscillation experiment in which the Fermilab NUMI beam is aimed at the Hyper-Kamiokande detector in Japan. In addition to the sensitivity to neutrissimos, we analyze the capabilities of these experiments to constraint the coupling constants and masses of new particles in various models of new physics suggested in the literature. The models we consider are: neutrissimo models, models with generation distinguishing Z's such as topcolor assisted technicolor, models containing various types of leptoquarks, R-parity violating SUSY, and extended Higgs sector models. In several cases, we find that the limits thus obtained could be competitive with those expected from direct searches at the LHC. In the event that any of the particles discussed here are discovered at the LHC, then the observation, or non-observation, of these particles in the NuSOnG and Fermilab-to-Hyper-Kamiokande experiments could help in identifying what type of particle had been observed.
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    Dark energy and string theory
    Berglund, Per; Hübsch, Tristan; Minic, Djordje (2019-11-10)
    A radiatively stable de Sitter spacetime is constructed by considering an intrinsically non-commutative and generalized-geometric formulation of string theory, which is related to a family of F-theory models endowed with non-trivial anisotropic axion-dilaton backgrounds. In particular, the curvature of the canonically conjugate dual space provides for a positive cosmological constant to leading order, that satisfies a radiatively stable see-saw-like formula, which in turn induces the dark energy in the observed spacetime. We also comment on the non-commutative phase of the non-perturbative formulations of string theory/quantum gravity implied by this approach.
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    Dark matter, infinite statistics, and quantum gravity
    Ho, C. M.; Minic, Djordje; Ng, Y. J. (American Physical Society, 2012-05-21)
    We elaborate on our proposal regarding a connection between global physics and local galactic dynamics via quantum gravity. This proposal calls for the concept of MONDian dark matter which behaves like cold dark matter at cluster and cosmological scales but emulates modified Newtonian dynamics (MOND) at the galactic scale. In the present paper, we first point out a surprising connection between the MONDian dark matter and an effective gravitational Born-Infeld theory. We then argue that these unconventional quanta of MONDian dark matter must obey infinite statistics, and the theory must be fundamentally nonlocal. Finally, we provide a possible top-down approach to our proposal from the matrix theory point of view.
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    Effect of the minimal length uncertainty relation on the density of states and the cosmological constant problem
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
    We investigate the effect of the minimal length uncertainty relation, motivated by perturbative string theory, on the density of states in momentum space. The relation is implemented through the modified commutation relation [(x) over cap (i),(p) over cap (j)]=i (h) over bar[(1+beta(p) over cap (2))delta(ij)+beta(')(p) over cap (i)(p) over cap (j)]. We point out that this relation, which is an example of a UV/IR relation, implies the finiteness of the cosmological constant. While our result does not solve the cosmological constant problem, it does shed new light on the relation between this outstanding problem and UV/IR correspondence. We also point out that the blackbody radiation spectrum will be modified at higher frequencies, but the effect is too small to be observed in the cosmic microwave background spectrum.
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    Effect of the minimal length uncertainty relation on the density of states and the cosmological constant problem
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
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    Exact solution of the harmonic oscillator in arbitrary dimensions with minimal length uncertainty relations
    Chang, Lay Nam; Minic, Djordje; Okamura, Naotoshi; Takeuchi, Tatsu (American Physical Society, 2002-06-15)
    We determine the energy eigenvalues and eigenfunctions of the harmonic oscillator where the coordinates and momenta are assumed to obey the modified commutation relations [(x) over cap (i),(p) over cap (j)]=i (h) over bar[(1+beta(p) over cap (2))delta(ij)+beta(')(p) over cap (i)(p) over cap (j)]. These commutation relations are motivated by the fact that they lead to the minimal length uncertainty relations which appear in perturbative string theory. Our solutions illustrate how certain features of string theory may manifest themselves in simple quantum mechanical systems through the modification of the canonical commutation relations. We discuss whether such effects are observable in precision measurements on electrons trapped in strong magnetic fields.