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Tatsu Takeuchi

Publications and source records attributed to Tatsu Takeuchi.

At least 37 records · Page 2Linked to original sources
arXiv2018

Ratchet Baryogenesis with an Analogy to the Forced Pendulum

A new scenario of baryogenesis via the ratchet mechanism is proposed based on an analogy to the forced pendulum. The oscillation of the inflaton field during the reheating epoch after inflation plays the role of the driving force, while the phase $θ$ of a scalar baryon field (a complex scalar field with baryon number) plays the role of the angle of the pendulum. When the inflaton is coupled to the scalar baryon, the behavior of the phase $θ$ can be analogous to that of the angle of the forced pendulum. If the oscillation of the driving force is adjusted to the pendulum's motion, a directed rotation of the pendulum is obtained with a non-vanishing value of $\dotθ$, which models successful baryogenesis since $\dotθ$ is proportional to the baryon number density. Similar ratchet models which lead to directed motion have been used in the study of molecular motors in biology. There, the driving force is supplied by chemical reactions, while in our scenario this role is played by the inflaton during the reheating epoch. Keywords: Baryogenesis; Reheating; Inflaton; Ratchet Model; Forced Rotating Pendulum

hep-ph↗
arXiv2017

Modified Dark Matter in Galaxies and Galaxy Clusters

Modified Dark Matter (MDM) is a phenomenological model of dark matter, inspired by gravitational thermodynamics, that naturally accounts for the universal acceleration constant observed in galactic rotation curve data; a critical acceleration related to the cosmological constant, $Λ$, appears as a phenomenological manifestation of MDM. We show that the resulting mass profiles, which are sensitve to $Λ$, are consistent with observations at the galactic and galaxy cluster scales. Our results suggest that dark matter mass profiles contain information about the cosmological constant in a non-trivial way.

astro-ph.CO↗
arXiv2017

Modified Dark Matter: Relating Dark Energy, Dark Matter and Baryonic Matter

Modified dark matter (MDM) is a phenomenological model of dark matter, inspired by gravitational thermodynamics. For an accelerating Universe with positive cosmological constant ($Λ$), such phenomenological considerations lead to the emergence of a critical acceleration parameter related to $Λ$. Such a critical acceleration is an effective phenomenological manifestation of MDM, and it is found in correlations between dark matter and baryonic matter in galaxy rotation curves. The resulting MDM mass profiles, which are sensitive to $Λ$, are consistent with observational data at both the galactic and cluster scales. In particular, the same critical acceleration appears both in the galactic and cluster data fits based on MDM. Furthermore, using some robust qualitative arguments, MDM appears to work well on cosmological scales, even though quantitative studies are still lacking. Finally, we comment on certain non-local aspects of the quanta of modified dark matter, which may lead to novel non-particle phenomenology and which may explain why, so far, dark matter detection experiments have failed to detect dark matter particles.

astro-ph.CO↗
arXiv2016

Supernova Physics at DUNE

The DUNE/LBNF program aims to address key questions in neutrino physics and astroparticle physics. Realizing DUNE's potential to reconstruct low-energy particles in the 10-100 MeV energy range will bring significant benefits for all DUNE's science goals. In neutrino physics, low-energy sensitivity will improve neutrino energy reconstruction in the GeV range relevant for the kinematics of DUNE's long-baseline oscillation program. In astroparticle physics, low-energy capabilities will make DUNE's far detectors the world's best apparatus for studying the electron-neutrino flux from a supernova. This will open a new window to unrivaled studies of the dynamics and neutronization of a star's central core in real time, the potential discovery of the neutrino mass hierarchy, provide new sensitivity to physics beyond the Standard Model, and evidence of neutrino quantum-coherence effects. The same capabilities will also provide new sensitivity to `boosted dark matter' models that are not observable in traditional direct dark matter detectors.

hep-ex↗
arXiv2016

The 750 GeV diphoton excess in unified $SU(2)_L\times SU(2)_R\times SU(4)$ models from noncommutative geometry

We discuss a possible interpretation of the $750$ GeV diphoton resonance, recently reported at the LHC, within a class of $SU(2)_L\times SU(2)_R\times SU(4)$ models with gauge coupling unification. The unification is imposed by the underlying non-commutative geometry (NCG), which in these models is extended to a left-right symmetric completion of the Standard Model (SM). Within such \textit{unified} $SU(2)_L\times SU(2)_R\times SU(4)$ models the Higgs content is restrictively determined from the underlying NCG, instead of being arbitrarily selected. We show that the observed cross sections involving the $750$ GeV diphoton resonance could be realized through a SM singlet scalar field accompanied by colored scalars, present in these unified models. In view of this result we discuss the underlying rigidity of these models in the NCG framework and the wider implications of the NCG approach for physics beyond the SM.

hep-ph↗
arXiv2016

Observable Effects of Quantum Gravity

We discuss the generic phenomenology of quantum gravity and, in particular, argue that the observable effects of quantum gravity, associated with new, extended, non-local, non-particle-like quanta, and accompanied by a dynamical energy-momentum space, are not necessarily Planckian and that they could be observed at much lower and experimentally accessible energy scales.

gr-qc↗
arXiv2016

Modified Dark Matter

Modified dark matter (MDM, formerly known as MoNDian dark matter) is a phenomenological model of dark matter, inspired by quantum gravity. We review the construction of MDM by generalizing entropic gravity to de-Sitter space as is appropriate for an accelerating universe (in accordance with the Lambda-CDM model). Unlike cold dark matter models, the MDM mass profile depends on the baryonic mass. We successfully fit the rotation curves to a sample of 30 local spiral galaxies with a single free parameter (viz., the mass-to-light ratio for each galaxy). We show that dynamical and observed masses agree in a sample of 93 galactic clusters. We also comment on strong gravitational lensing in the context of MDM.

astro-ph.CO↗
arXiv2016

Testing Modified Dark Matter with Galaxy Clusters: Does Dark Matter know about the Cosmological Constant?

We discuss the possibility that the cold dark matter mass profiles contain information on the cosmological constant, and that such information constrains the nature of cold dark matter (CDM). We call this approach Modified Dark Matter (MDM). In particular, we examine the ability of MDM to explain the observed mass profiles of 13 galaxy clusters. Using general arguments from gravitational thermodynamics, we provide a theoretical justification for our MDM mass profile and successfully compare it to the NFW mass profiles both on cluster and galactic scales. Our results suggest that indeed the CDM mass profiles contain information about the cosmological constant in a non-trivial way.

astro-ph.CO↗
arXiv2015

Pati-Salam Unification from Non-commutative Geometry and the TeV-scale $W_R$ boson

We analyze the compatibility of the unified left-right symmetric Pati-Salam models motivated by non-commutative geometry and the TeV scale right-handed W boson suggested by recent LHC data. We find that the unification/matching conditions place conflicting demands on the symmetry breaking scales and that generating the required W_R mass and coupling is non-trivial.

hep-ph↗
arXiv2015

Position and momentum uncertainties of a particle in a V-shaped potential under the minimal length uncertainty relation

We calculate the uncertainties in the position and momentum of a particle in the 1D potential V(x)=F|x|, F>0, when the position and momentum operators obey the deformed commutation relation [x,p]=i\hbar(1+βp^2), β>0. As in the harmonic oscillator case, which was investigated in a previous publication, the Hamiltonian H_1 = p^2/2m + F|x| admits discrete positive energy eigenstates for both positive and negative mass. The uncertainties for the positive mass states behave as Δx ~ 1/Δp as in the β=0 limit. For the negative mass states, however, in contrast to the harmonic oscillator case where we had Δx ~ Δp, both Δx and Δp diverge. We argue that the existence of the negative mass states and the divergence of their uncertainties can be understood by taking the classical limit of the theory. Comparison of our results is made with previous work by Benczik.

hep-th↗
arXiv2015

Running of Oscillation Parameters in Matter with Flavor-Diagonal Non-Standard Interactions of the Neutrino

In this article we unravel the role of matter effect in neutrino oscillation in the presence of lepton-flavor-conserving, non-universal non-standard interactions (NSI's) of the neutrino. Employing the Jacobi method, we derive approximate analytical expressions for the effective mass-squared differences and mixing angles in matter. It is shown that, within the effective mixing matrix, the Standard Model (SM) W-exchange interaction only affects $θ_{12}$ and $θ_{13}$, while the flavor-diagonal NSI's only affect $θ_{23}$. The CP-violating phase $δ$ remains unaffected. Using our simple and compact analytical approximation, we study the impact of the flavor-diagonal NSI's on the neutrino oscillation probabilities for various appearance and disappearance channels. At higher energies and longer baselines, it is found that the impact of the NSI's can be significant in the numu to numu channel, which can probed in future atmospheric neutrino experiments, if the NSI's are of the order of their current upper bounds. Our analysis also enables us to explore the possible degeneracy between the octant of $θ_{23}$ and the sign of the NSI parameter for a given choice of mass hierarchy in a simple manner.

hep-ph↗
arXiv2015

The Higgs Mass, Superconnections and the TeV-scale Left-Right Symmetric Model

We discuss the physical implications of formulating the Standard Model (SM) in terms of the superconnection formalism involving the superalgebra su(2/1). In particular, we discuss the prediction of the Higgs mass according to the formalism and point out that it is ~170 GeV, in clear disagreement with experiment. To remedy this problem, we extend the formalism to the superalgebra su(2/2), which extends the SM to the left-right symmetric model (LRSM) and accommodates a ~126 GeV Higgs. Both the SM in the su(2/1) case and the LRSM in the su(2/2) case are argued to emerge at ~4 TeV from an underlying theory in which the spacetime geometry is modified by the addition of a discrete extra dimension. The formulation of the exterior derivative in this model space suggests a deep connection between the modified geometry, which can be described in the language of non-commutative geometry (NCG), and the spontaneous breaking of the gauge symmetries. The implication is that spontaneous symmetry breaking could actually be geometric/quantum gravitational in nature. The non-decoupling phenomenon seen in the Higgs sector can then be reinterpreted in a new light as due to the mixing of low energy (SM) physics and high energy physics associated with quantum gravity, such as string theory. The phenomenology of a TeV scale LRSM is also discussed, and we argue that some exciting discoveries may await us at the LHC, and other near-future experiments.

hep-ph↗
arXiv2014

Analytical Approximation of the Neutrino Oscillation Matter Effects at large $θ_{13}$

We argue that the neutrino oscillation probabilities in matter are best understood by allowing the mixing angles and mass-squared differences in the standard parametrization to `run' with the matter effect parameter $a=2\sqrt{2}G_F N_e E$, where $N_e$ is the electron density in matter and $E$ is the neutrino energy. We present simple analytical approximations to these `running' parameters. We show that for the moderately large value of $θ_{13}$, as discovered by the reactor experiments, the running of the mixing angle $θ_{23}$ and the CP violating phase $δ$ can be neglected. It simplifies the analysis of the resulting expressions for the oscillation probabilities considerably. Approaches which attempt to directly provide approximate analytical expressions for the oscillation probabilities in matter suffer in accuracy due to their reliance on expansion in $θ_{13}$, or in simplicity when higher order terms in $θ_{13}$ are included. We demonstrate the accuracy of our method by comparing it to the exact numerical result, as well as the direct approximations of Cervera et al., Akhmedov et al., Asano and Minakata, and Freund. We also discuss the utility of our approach in figuring out the required baseline lengths and neutrino energies for the oscillation probabilities to exhibit certain desirable features.

hep-ph↗
arXiv2014

Quantum F_un: the q=1 Limit of Galois Field Quantum Mechanics, Projective Geometry, and the Field with One Element

We argue that the q=1 limit of Galois Field Quantum Mechanics, which was constructed on a vector space over the Galois Field F_q=GF(q), corresponds to its `classical limit,' where superposition of states is disallowed. The limit preserves the projective geometry nature of the state space, and can be understood as being constructed on an appropriately defined analogue of a `vector' space over the `field with one element' F_1.

quant-ph↗
arXiv2014

Testing MONDian Dark Matter with Galactic Rotation Curves

MONDian dark matter (MDM) is a new form of dark matter quantum that naturally accounts for Milgrom's scaling, usually associated with modified Newtonian dynamics (MOND), and theoretically behaves like cold dark matter (CDM) at cluster and cosmic scales. In this paper, we provide the first observational test of MDM by fitting rotation curves to a sample of 30 local spiral galaxies (z approximately 0.003). For comparison, we also fit the galactic rotation curves using MOND, and CDM. We find that all three models fit the data well. The rotation curves predicted by MDM and MOND are virtually indistinguishable over the range of observed radii (~1 to 30 kpc). The best-fit MDM and CDM density profiles are compared. We also compare with MDM the dark matter density profiles arising from MOND if Milgrom's formula is interpreted as Newtonian gravity with an extra source term instead of as a modification of inertia. We find that discrepancies between MDM and MOND will occur near the center of a typical spiral galaxy. In these regions, instead of continuing to rise sharply, the MDM mass density turns over and drops as we approach the center of the galaxy. Our results show that MDM, which restricts the nature of the dark matter quantum by accounting for Milgrom's scaling, accurately reproduces observed rotation curves.

astro-ph.CO↗
arXiv2013

Quantum Systems based upon Galois Fields: from Sub-quantum to Super-quantum Correlations

In this talk we describe our recent work on discrete quantum theory based on Galois fields. In particular, we discuss how discrete quantum theory sheds new light on the foundations of quantum theory and we review an explicit model of super-quantum correlations we have constructed in this context. We also discuss the larger questions of the origins and foundations of quantum theory, as well as the relevance of super-quantum theory for the quantum theory of gravity.

quant-ph↗
arXiv2013

The Higgs Mass and the Emergence of New Physics

We investigate the physical implications of formulating the electroweak (EW) part of the Standard Model (SM) in terms of a superconnection involving the supergroup SU(2/1). In particular, we relate the observed Higgs mass to new physics at around 4 TeV. The ultraviolet incompleteness of the superconnection approach points to its emergent nature. The new physics beyond the SM is associated with the emergent supergroup SU(2/2), which is natural from the point of view of the Pati-Salam model. Given that the Pati-Salam group is robust in certain constructions of string vacua, these results suggest a deeper connection between low energy (4 TeV) and high energy (Planck scale) physics via the violation of decoupling in the Higgs sector.

hep-ph↗