Browsing by Author "Takeuchi, Tatsu"
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- The 750 GeV diphoton excess in unified SU(2)(L) x SU(2)(R) x SU(4) models from noncommutative geometryAydemir, U.; Minic, Djordje; Sun, C.; Takeuchi, Tatsu (World Scientific, 2016-06-14)
- ACD estimation of the S-parameter revisitedIgnjatovic, S. R.; Takeuchi, Tatsu; Wijewardhana, L. C. R. (Elsevier, 1997-05-29)
- Analysis of JLab E12-14-012 Ti(e,e′p) Data and Determination of the Ti Spectral FunctionLanham, Clint A. (Virginia Tech, 2023-05-26)Future long baseline neutrino oscillation experiments like the Deep Underground Neutrino Experiment (DUNE) rely on Liquid Argon Time Projection Chamber (LArTPC) detectors. The reconstruction of neutrino flavors and energy through interactions with Argon is a critical issue for assuring the DUNE success. The neutrino-Argon nuclear cross section is one of the biggest sources of uncertainty in measuring possible Charge-Parity Violation (CPV) in the neutrino (ν) sector and decoupling background like matter-effects. This thesis summarizes the exclusive electron scattering measurement of the Jefferson Lab E12-14-012 experiment. The E12-14-012 experiment goals are to explore the Ti(e,e′p) and Ar(e,e′p) reactions in a wide range of kinematics in order to determine the spectral function of protons and neutrons in Argon. The measurements made in E12-14-012 are the first of their kind in argon and are a pivotal step in understanding the electron-Argon interaction and its relation to neutrino scattering. Titanium was specifically chosen under an assumption that its protons can be a proxy for argon neutron spectral functions. The analysis of the exclusive electron scattering in titanium is described in detail in this thesis.
- An analysis of nonoblique corrections to the Zb¯b vertexTakeuchi, Tatsu; Grant, Aaron K.; Rosner, Jonathan L. (1994)We present a model–independent analysis of the Zb¯b vertex, with the aim of constraining contributions of new physics to the left- and right–handed couplings of the b. We find that the left–handed coupling of the b is quite narrowly constrained by present data, but that the right–handed coupling is still largely unconstrained.
- An analysis of Precision Electroweak Measurements: Summer 98 UpdateGrant, Aaron K.; Takeuchi, Tatsu (1998-07)We update our analysis of precision electroweak measurements using the latest data announced at Moriond, March 1998. Possible oblique corrections from new physics are parametrized using the STU formalism of Ref.[1], and non-oblique corrections to the Zbb vertex are parametrized using the xi_b zeta_b formalism of Ref.[2]. The implications of the analysis on minimal SU(5) grand unification is discussed.
- Analytical approximation of the neutrino oscillation matter effects at large theta (13)Agarwalla, S. K.; Kao, Y.; Takeuchi, Tatsu (Springer, 2014-04-07)
- Applications of Field Theory to Reaction Diffusion Models and Driven Diffusive SystemsMukherjee, Sayak (Virginia Tech, 2009-08-25)In this thesis, we focus on the steady state properties of two systems which are genuinely out of equilibrium. The first project is an application of dynamic field theory to a specific non equilibrium critical phenomenon, while the second project involves both simulations and analytical calculations. The methods of field theory are used on both these projects. In the first part of this thesis, we investigate a generalization of the well-known field theory for directed percolation (DP). The DP theory is known to describe an evolving population, near extinction. We have coupled this evolving population to an environment with its own nontrivial spatio-temporal dynamics. Here, we consider the special case where the environment follows a simple relaxational (model A) dynamics. We find two marginal couplings with upper critical dimension of four, which couple the two theories in a nontrivial way. While the Wilson-Fisher fixed point remains completely unaffected, a mismatch of time scales destabilizes the usual DP fixed point. Some open questions and future work remain. In the second project, we focus on a simple particle transport model far from equilibrium, namely, the totally asymmetric simple exclusion process (TASEP). While its stationary properties are well studied, many of its dynamic features remain unexplored. Here, we focus on the power spectrum of the total particle occupancy in the system. This quantity exhibits unexpected oscillations in the low density phase. Using standard Monte Carlo simulations and analytic calculations, we probe the dependence of these oscillations on boundary effects, the system size, and the overall particle density. Our simulations are fitted to the predictions of a linearized theory for the fluctuation of the particle density. Two of the fit parameters, namely the diffusion constant and the noise strength, deviate from their naive bare values [6]. In particular, the former increases significantly with the system size. Since this behavior can only be caused by nonlinear effects, we calculate the lowest order corrections in perturbation theory. Several open questions and future work are discussed.
- Aspects of SupersymmetryJia, 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.
- B-decay anomalies and scalar leptoquarks in unified Pati-Salam models from noncommutative geometryAydemir, 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.
- Bell's Inequalities, Superquantum Correlations, and String TheoryChang, 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.
- Bell's Inequalities, Superquantum Correlations, and String TheoryChang, 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.
- Biorthogonal quantum mechanics: super-quantum correlations and expectation values without definite probabilitiesChang, 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.
- Calibration of the COHERENT Neutrino Flux Normalization DetectorTellez-Giron-Flores, Karla Rosita (Virginia Tech, 2023-11-14)Neutrinos hold the promise of untangling many unresolved questions in particle physics. Their unique properties and behaviors offer a distinctive window into understanding the fundamentals of the universe, potentially providing answers to some of the most deep puzzles in modern physics. CEνNS, or Coherent Elastic Neutrino-Nucleus Scattering, is a process where a neutrino interacts with an atomic nucleus and scatters away, leaving the nucleus to recoil. CEνNS is an important area of study for understanding neutrino properties as well as their role in the universe. The COHERENT collaboration was the first to measure CEνNS, using neutrinos from the Spallation Neutron Source (SNS). The direct measurement of the SNS neutrino flux is vital for the precision of CEνNS measurements. This work introduces the latest addition to the COHERENT's armory –a D2O detector specifically designed to measure the SNS neutrino flux. In the present dissertation, the emphasis is made on the steps taken to operationalize COHERENT's D2O detector. This work unfolds the intensive simulation work directed to determine the detector's optimal design, ensuring it stands strong to the demands of neutrino physics experiments. Establishing the detector's calibration is essential to its operational phase. A dedicated calibration system, described in detail in this work, has been developed, utilizing encapsulated LED flashers controlled by a microcontroller unit to ensure the systematic and reliable calibration of the detector. A significant portion of the document is devoted to the calibration analysis, where we use Michel electrons to obtain an energy scale for the detector, thereby ensuring the reliability and accuracy of the future neutrino flux measurements.
- Charge assignments in multiple-U(1) gauge theoriesLoinaz, William; Takeuchi, Tatsu (American Physical Society, 1999-12-01)We discuss the choice of gauge field basis in multiple-U(1) gauge theories. We find that there is a preferred basis, specified by the charge orthogonality condition, in which the U(1) gauge fields do not mix under one-loop renormalization group running. [S0556-2821(99)04219-8].
- Charge assignments in multiple-U(1) gauge theoriesLoinaz, William; Takeuchi, Tatsu (American Physical Society, 1999-12-01)
- Choice of dispersion relation to calculate the QCD correction to Gamma(H->l(+)l(-))Takeuchi, Tatsu; Grant, Aaron K.; Worah, Mihir P. (American Physical Society, 1996-02-01)We use the Operator Product Expansion (OPE) of quark vacuum polarization functions to show that the dispersion relation of Kniehl and Sirlin will yield the correct result to all orders in αs when applied to the QCD correction to the leptonic decay width of the Higgs boson.
- Classical Implications of the Minimal Length Uncertainty RelationBenczik, 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.
- Comment on the Dispersion Relations used to Calculate ΔρTakeuchi, Tatsu; Grant, Aaron K.; Worah. Mihir (American Physical Society, 1995-06-01)We use the operator product expansion (OPE) to show that nonperturbative QCD corrections to Δρ can be calculated using unsubtracted dispersion relations for either the transverse or the longitudinal vacuum polarization functions. Recent calculations of the nonperturbative contribution to Δρ based on a non-relativistic calculation of corrections to the t¯t threshold are inconsistent with this result.
- Constraining New Physics with Colliders and NeutrinosSun, 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.
- Constraining new physics with vertex correctionsTakeuchi, Tatsu; Lebedev, O.; Loinaz, William (1999)