arXiv subjects

Akio Sugamoto

Publications and source records attributed to Akio Sugamoto.

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

Generalized Heisenberg-Euler formula in Abelian gauge theory with parity violation

A generalized Heisenberg-Euler formula is given for an Abelian gauge theory having vector as well as axial vector couplings to a massive fermion. So, the formula is applicable to a parity-violating theory. The gauge group is chosen to be $U(1)$. The formula is quite similar to that in quantum electrodynamics, but there is a complexity in which one factor (related to spin) is expressed in terms of the expectation value. The expectation value is evaluated by the contraction with the one-dimensional propagator in a given background field. The formula affords a basis to the vacuum magnetic birefringence experiment, which aims to probe the dark sector, where the interactions of the light fermions with the gauge fields are not necessarily parity conserving.

hep-ph↗

arXiv2016

Construction of a Model of Monopolium and its Search via Multi-Photon Channels at LHC

A model of monopolium is constructed based on an electromagnetic dual formulation of Zwanziger and lattice gauge theory. To cope with the strong coupling nature of the magnetic charge, for which the monopole is confined, $ U(1) $ lattice gauge theory is applied. The monopole is assumed to have a finite-sized inner structure based on a 't Hooft-Polyakov like solution in which the magnetic charge is uniformly distributed on the surface of a sphere. The monopole and antimonopole potential becomes linear plus Coulomb outside the sphere and is constant inside. Numerical estimation gives two kinds of solutions: One which has a small binding energy, and hence the para-($ J=0 $) and ortho-($ J=1 $) monopoliums have degenerate masses. For the parameter choices considered, they both have $ \mathcal{O}(1-10) $ TeV masses and are very short-lived. The other solution has a small monopole mass and large binding energy, with an illustrative example of parameter choices giving a 750 GeV para-monopolium and 1.4 TeV ortho-monopolium. The production rate of the former is one order of magnitude smaller than the announced enhancement, but they may be the target of future LHC searches and the 100 TeV colliders.

hep-ph↗

arXiv2016

A simulation of hydrodynamics on non-commutative space

A simulation of the hydrodynamics on the two dimensional non-commutative space is performed, in which the space coordinates $(x, y)$ are non-commutative, satisfying the commutation relation $[x, y]=i θ$. The Navier-Stokes equation has an extra force term which reflects the non-commutativity of the space, being proportional to $θ^2$. This parameter $θ$ is related to the minimum size of fluid particles which is implied by the uncertainty principle, $Δx Δy \ge θ/2$. To see the effect of this parameter on the flow, following situation is considered. An obstacle placed in the middle of the stream, separates the flow into small slit and large slit, but the flow is joined afterwards in the down stream. For the Reynolds number 700, the behavior of the flows with and without $θ$ is observed to differ, and the difference is seen to be correlated to the difference of the activity of vortices in the down stream. The oscillation of the flow rate at the small slit diminishes after the certain time in the usual flow when the "two attached eddies" appear. In the non-commutative flow this two attached eddies appear from the beginning and the behavior of the flows does not fluctuate largely. The irregularity in the flow existing in the beginning disappears after the certain time.

physics.flu-dyn↗

arXiv2015

Application of Kawaguchi Lagrangian formulation to string theory

String-scalar duality proposed by Y. Hosotani and membrane-scalar duality by A. Sugamoto are reexamined in the context of Kawaguchi Lagrangian formulation. The characteristic feature of this formulation is the indifferent nature of fields and parameters. Therefore even the exchange of roles between fields and parameters is possible. In this manner, dualities above can be proved easily. Between Kawaguchi metrics of the dually related theories, a simple relation is found. As an example of the exchange between fermionic fields and parameters, a replacement of the role of Grassmann parameters of the 2-dimensional superspace by the 9th component of Neveu-Schwarz-Ramond (NSR) fermions is studied in superstring model. Compactification is also discussed in this model.

hep-th↗

arXiv2014

Hydrodynamics on non-commutative space --A step toward hydrodynamics of granular materials--

Hydrodynamics on non-commutative space is studied based on a formulation of hydrodynamics by Y. Nambu in terms of Poisson and Nambu brackets. Replacing these brackets by Moyal brackets with a parameter $θ$, a new hydrodynamics on non-commutative space is derived. It may be a step toward to find the hydrodynamics of granular materials whose minimum volume is given by $θ$. To clarify this minimum volume, path integral quantization and uncertainty relation of Nambu dynamics are examined.

hep-th↗

arXiv2014

Is it possible to unify three kinds of Dark Matters into a Kaluza-Klein Neutrino?

A unified theory of including all kinds of dark matters into a single species (field) is discussed. In particular, it is considered that the Warm Dark matter (WDM), the existence of which may be required by the detailed $N$-body simulations of galaxies using the $Λ$CDM model, is the right-handed neutrino, the Hot Dark Matter (HDM) is the left-handed neutrino, and the Cold Dark Matter (CDM) is the first Kaluza-Klein (KK) mode of neutrino. The study on how to detect the first KK neutrino mode as CDM by LHC, SuperK, and IceCube is also explained. Not only these detectors but also the recent experiments, such as DAMA/LIBRA, PAMELA, XENON100, and XMASS as well as the various satellite detectors including Planck should be examined.

hep-ph↗

arXiv2013

Ratchet Model of Baryogenesis

We propose a toy model of baryogenesis which applies the `ratchet mechanism,' used frequently in the theory of biological molecular motors, to a model proposed by Dimopoulos and Susskind.

hep-ph↗

arXiv2008

Factorization of number into prime numbers viewed as decay of particle into elementary particles conserving energy

Number theory is considered, by proposing quantum mechanical models and string-like models at zero and finite temperatures, where the factorization of number into prime numbers is viewed as the decay of particle into elementary particles conserving energy. In these models, energy of a particle labeled by an integer $n$ is assumed or derived to being proportional to $\ln n$. The one-loop vacuum amplitudes, the free energies and the partition functions at finite temperature of the string-like models are estimated and compared with the zeta functions. The $SL(2, {\bf Z})$ modular symmetry, being manifest in the free energies is broken down to the additive symmetry of integers, ${\bf Z}_{+}$, after interactions are turned on. In the dynamical model existing behind the zeta function, prepared are the fields labeled by prime numbers. On the other hand the fields in our models are labeled, not by prime numbers but by integers. Nevertheless, we can understand whether a number is prime or not prime by the decay rate, namely by the corresponding particle can decay or can not decay through interactions conserving energy. Among the models proposed, the supersymmetric string-like model has the merit of that the zero point energies are cancelled and the energy levels may be stable against radiative corrections.

physics.gen-ph↗

arXiv2008

Experimental investigation of a control scheme for a zero-detuning resonant sideband extraction interferometer for next-generation gravitational-wave detectors

Some next-generation gravitational-wave detectors, such as the American Advanced LIGO project and the Japanese LCGT project, plan to use power recycled resonant sideband extraction (RSE) interferometers for their interferometer's optical configuration. A power recycled zero-detuning (PRZD) RSE interferometer, which is the default design for LCGT, has five main length degrees of freedom that need to be controlled in order to operate a gravitational-wave detector. This task is expected to be very challenging because of the complexity of optical configuration. A new control scheme for a PRZD RSE interferometer has been developed and tested with a prototype interferometer. The PRZD RSE interferometer was successfully locked with the control scheme. It is the first experimental demonstration of a PRZD RSE interferometer with suspended test masses. The result serves as an important step for the operation of LCGT.

gr-qc↗

arXiv2008

Can the Baryon Number Density and the Cosmological Constant be interrelated?

A toy model is proposed in which the cosmological constant and the baryon number density of the universe are interrelated. The model combines the mechanism of Dimopoulos and Susskind in which the baryon number density of the universe is generated by the time-dependence of the phase of a complex scalar field, i.e. its `angular momentum' in the two-dimensinal complex field space, with that of Yoshimura in which the `centrifugal force' due the `angular momentum' pushes the vacuum expectation value of the scalar field out of a negative potential minimum and provides a small but positive cosmological constant. Unfortunately, our model fails to relate the smallness of the two numbers directly, requiring a fine-tuning of the negative potential minimum.

hep-ph↗

arXiv2007

Baryogenesis by Quantum Gravity

A novel mechanism of baryogenesis is proposed on the basis of the phase transition from the conformal invariant space-time to the Einstein space-time in quantum gravity. Strong-coupling gravitational excitations with dynamical mass about 10^17 GeV are generated at the transition. They eventually decay into ordinary matters. As a realization of unparticle physics we show that the low energy effective interactions between the gravitational potential describing the excitation and the non-conserving matter currents by the axial anomalies can explain matter asymmetry out of thermal equilibrium.

hep-ph↗

arXiv2007

An Exotic Approach to Hadron Physics

An exotic approach to hadrons is discussed. It is based on the recently developed open-closed string duality explicitly conjectured as the AdS/CFT correspondence. Mesons as well as pentaquarks are studied in this approach. Spins are introduced as distribution functions over the string, and a second quantization method of string theory is examined and used to estimate the mass and decay width of various hadrons. This approach provides a way to understand the structure of flavor by a configuration of probe branes.

hep-ph↗

arXiv2006

Meson Strings and Flavor Branes

In a QCD-like string model based on D6 flavor branes in the presence of D4 color branes wrapping one of the compactified dimension on an $S^1$, the shape of meson strings in the five dimensional curved space as well as the potential between quark and anti-quark are investigated. The flavor branes on which both ends of a meson string live are assumed to be separated in this five dimensional space, depending on the values of the constituent quark masses. It is shown in this picture that the meson string with different flavors on both ends changes its shape at a critical distance. There is, however, no critical distance for the meson with the same flavors. At this critical distance the potential between quark and anti-quark with different flavors gives a point of reflection and changes its shape around this point. Accordingly, the attractive force between quark and anti-quark seems to become stronger when the distance of flavor branes connecting meson strings becomes larger. This indicates quark systems with different flavors can form high-density states.

hep-ph↗

arXiv2005

Distributed Spin in a String Picture of Hadrons

In a string picture of hadrons, spins are distributed over the whole configuration of string. According to this picture, spin of hadron is discussed in a dual gravity theory of QCD, towards realistic mass formulae of hadrons including hyperfine interactions.

hep-th↗

arXiv2004

Dynamical Origin of Duality between Gauge Theory and Gravity

Dynamical origin of duality between gauge theory and gravity is studied using the dual transformation and the formation of graviton as a collective excitation of dual gauge bosons. In this manner, electric-magnetic duality in gauge theory is reduced to the duality between gauge theory and gravity.

hep-th↗

arXiv2004

Pentaquark Baryons in String Theory

The recently observed pentaquark baryons $Θ^{+}$ and $Ξ^{--}$ are studied in the dual gravity theory of QCD. By developing a general formulation useful for studying the branched string web in a curved space, simple mass formulae of the pentaquark baryons are derived in the Maldacena prototype model for supersymmetric QCD and a more realistic model for ordinary QCD. Even though the approximations adopted here in deriving these formulae are extremely naive, the predicted values of the masses do not differ significantly from their experimental values. We thus conclude that this approach is promising for the purpose of obtaining a description of the observed masses of pentaquarks and of their extremely narrow decay widths. With the aim of constructing more reliable mass formulae, a preliminary sketch is given of how spin, the hyperfine interaction and parity are considered in the string picture.

hep-ph↗

arXiv2004

Singular Gauge Transformation in Non-Commutative U(2) Gauge Theory

A method developed by Polychronakos to study singular gauge transformations in 1+2 dimensional non-commutative Chern-Simons gauge theory is generalized from U(1) group to U(2) group. The method clarifies the singular behavior of topologically non-trivial gauge transformations in non-commutative gauge theory, which appears when the gauge transformations are viewed from the commutative gauge theory equivalent to the commutative theory.

hep-th↗