arXiv subjects

Noriaki Kitazawa

Publications and source records attributed to Noriaki Kitazawa.

At least 55 records · Page 3Linked to original sources

arXiv2004

Dynamical Generation of Yukawa Interactions in Intersecting D-brane Models

We construct a supersymmetric composite model in type IIA T^6/(Z_2 x Z_2) orientifold with intersecting D6-branes. Four generations of quarks and leptons are naturally emerged as composite fields at low energies. Two pairs of light electroweak Higgs doublets are also naturally obtained. The hierarchical Yukawa couplings for the quark-lepton masses can be generated by the interplay between the string-level higher dimensional interactions among "preons" and the dynamics of the confinement of "preons". Besides having four generations of quarks and leptons, the model is not realistic in some points: some exotic particles, one additional U(1) gauge symmetry, no explicit mechanism for supersymmetry breaking, and so on. This model is a toy model to illustrate a new mechanism of dynamical generation of Yukawa couplings for the masses and mixings of quarks and leptons.

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arXiv2004

Supersymmetric Composite Models on Intersecting D-branes

We construct supersymmetric composite models of quarks and leptons from type IIA T^6/(Z_2 x Z_2) orientifolds with intersecting D6-branes. In case of T^6 = T^2 x T^2 x T^2 with no tilted T^2, a composite model of the supersymmetric SU(5) grand unified theory with three generations is constructed. In case of that one T^2 is tilted, a composite model with SU(3)_c x SU(2)_L x U(1)_Y gauge symmetry with three generations is constructed. These models are not realistic, but contain fewer additional exotic particles and U(1) gauge symmetries due to the introduction of the compositeness of quarks and leptons. The masses of some exotic particles are naturally generated through the Yukawa interactions among "preons".

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arXiv2003

Gaugino Condensation in Heterotic Fivebrane Background

The gaugino propagator is calculated by explicitly considering the propagation of a heterotic string between two different points in space-time using the non-trivial world-sheet conformal field theory for the fivebrane background. We find that there are no propagations of gaugino which is in the spinor representation of the non-trivial four-dimensional space of the fivebrane background. This result is consistent with the arguments on the fermion zero-modes of the fivebrane background in the low-energy heterotic supergravity theory. Furthermore, assuming the continuous limit to the flat space-time background at the place far away from the fivebrane, we suggest an effective propagator which is effective only at the place far away from the fivebrane in the flat space-time limit. From the effective propagator we evaluate a possible gaugino pair condensation. The result is consistent with the suggested scenario of the gaugino condensation in the fivebrane background in the low-energy heterotic supergravity theory.

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arXiv2003

Fermion Propagators in Type II Fivebrane Backgrounds

The fermion propagators in the fivebrane background of type II superstring theories are calculated. The propagator can be obtained by explicitly evaluating the transition amplitude between two specific NS-R boundary states by the propagator operator in the non-trivial world-sheet conformal field theory for the fivebrane background. The propagator in the field theory limit can be obtained by using point boundary states. We can explicitly investigate the lowest lying fermion states propagating in the non-trivial ten-dimensional space-time of the fivebrane background: M^6 x W_k^(4), where W_k^(4) is the group manifold of SU(2)_k x U(1). The half of the original supersymmetry is spontaneously broken, and the space-time Lorentz symmetry SO(9,1) reduces to SO(5,1) in SO(5,1) x SO(4) \subset SO(9,1) by the fivebrane background. We find that there are no propagations of SO(4) (local Lorentz) spinor fields, which is consistent with the arguments on the fermion zero-modes in the fivebrane background of low-energy type II supergravity theories.

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arXiv2003

Fermionic zeromodes in heterotic fivebrane backgrounds

We investigate the explicit form of the fermionic zeromodes in heterotic fivebrane backgrounds. By explicitly solving the fermionic field equations in fivebrane backgrounds, two normalizable and physical fermionic zeromodes are obtained. Each of these zeromodes has a non-vanishing gravitino component. We suggest a possible scenario of the gravitino pair condensation.

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arXiv2002

Fermionic zero-modes in type II fivebrane backgrounds

The explicit form of the fermionic zero-modes in the fivebrane backgrounds of type IIA and IIB supergravity theories is investigated. In type IIA fivebrane background there are four zero-modes of gravitinos and dilatinos. In type IIB fivebrane background four zero-modes of dilatinos and no zero-modes of gravitinos are found. These zero-modes indicate the four-fermion condensates which have been suggested in a calculation of the tension of the D-brane in fivebrane backgrounds.

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arXiv2002

Gravitino condensation in fivebrane backgrounds

We calculate the tension of the D3-brane in the fivebrane background which is described by the exactly solvable SU(2)_k x U(1) world-sheet conformal field theory with large Kac-Moody level k. The D3-brane tension is extracted from the amplitude of one closed string exchange between two parallel D3-branes, and the amplitude is calculated by utilizing the open-closed string duality. The tension of the D3-brane in the background does not coincide with the one in the flat space-time even in the flat space-time limit: k -> infinity. The finite curvature effect should vanish in the flat space-time limit and only the topological effect can remain. Therefore, the deviation indicates the condensation of gravitino and/or dilatino which has been expected in the fivebrane background as a gravitational instanton.

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arXiv2000

R-mediation of Dynamical Supersymmetry Breaking

We propose a simple scenario of the dynamical supersymmetry breaking in four dimensional supergravity theories. The supersymmetry breaking sector is assumed to be completely separated as a sequestered sector from the visible sector, except for the communication by the gravity and U(1)_R gauge interactions, and the supersymmetry breaking is mediated by the superconformal anomaly and U(1)_R gauge interaction. Supersymmetry is dynamically broken by the interplay between the non-perturbative effect of the gauge interaction and Fayet-Iliopoulos D-term of U(1)_R which necessarily exists in supergravity theories with gauged U(1)_R symmetry. We construct an explicit model which gives phenomenologically acceptable mass spectrum of superpartners with vanishing (or very small) cosmological constant.

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arXiv2000

Dynamical Supersymmetry Breaking with Gauged U(1)_R Symmetry

We propose a simple model of dynamical supersymmetry breaking in the context of minimal supergravity with gauged $U(1)_R$ symmetry. The model is based on the gauge group $SU(2) \times U(1)_R$ with three matters. Since the $U(1)_R$ symmetry is gauged, the Fayet-Iliopoulos D-term appears due to the symmetry of supergravity. On the other hand, the superpotential generated dynamically by the SU(2) gauge dynamics leads to run away potential. Since the supersymmetric vacuum condition required by the D-term potential contradicts the one required by the superpotential, supersymmetry is broken. The supersymmetry breaking scale is controlled by the dynamical scale of the SU(2) gauge interaction. We can choose the parameters in our model for vanishing cosmological constant. Our model is phenomenologically viable with the gravitino mass of order 1 TeV or 10 TeV.

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arXiv2000

Models of Dynamical Supersymmetry Breaking with Gauged $U(1)_R$ Symmetry

We present simple models of dynamical supersymmetry breaking with gauged U(1)_R symmetry. The minimal supersymmetric standard model and supersymmetric SU(5) GUT are considered as the visible sector. The anomaly cancellation conditions for U(1)_R are investigated in detail and simple solutions of the R-charge assignments are found. We show that this scenario of dynamical supersymmetry breaking is phenomenologically viable with the gravitino mass of order 1 TeV or 10 TeV.

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arXiv1999

Physical auxiliary field in supersymmetric QCD with explicit supersymmetry breaking

It is shown that the auxiliary field in the low-energy effective theory of the supersymmetric QCD (SU(N_c) gauge symmetry with flavors N_f < N_c) can be understood as a physical degree of freedom, once the supersymmetry is explicitly broken. Although the vacuum expectation value of the auxiliary field is just a measure of the supersymmetry breaking in the perturbative treatment of the supersymmetry breaking, it can be the vacuum expectation value of the quark bilinear operator in the non-perturbative treatment of the supersymmetry breaking. We show that the vacuum expectation value remains finite in the limit of the infinite supersymmetry-breaking mass of the squark. We have to take the large N_c limit simultaneously to keep the low-energy effective Kaehler potential being in good approximation.

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arXiv1999

Determination of the dynamically generated Yukawa coupling in supersymmetric QCD

The strength of the dynamically generated Yukawa coupling among composite fields is calculated. The system of N=1 supersymmetric SU(2) gauge theory with massive three flavors is considered as an example. We use the techniques of "integrating in" the gluino-gluino bound state in the low energy effective theory and the instanton calculation and Shifman-Vainshtein-Zakharov sum rule (QCD sum rule) in the fundamental theory. The obtained value of the Yukawa coupling is of the order of unity. The method which is developed in this paper can be applied to the other supersymmetric gauge theories.

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arXiv1999

Towards exact results of QED from supersymmetry

To obtain some exact results of U(1) gauge theory (QED), we construct the low energy effective action of N=2 supersymmetric QED with a massless matter and Fayet-Iliopoulos term, assuming no confinement. The harmonic superspace formalism for N=2 extended supersymmetry makes the construction easy. We analyze the vacuum structure and find no vacuum. It suggests the confinement in non-supersymmetric QED at low energies.

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arXiv1998

Quark Mass Hierarchy in the Supersymmetric Composite Model

A mechanism to have the quark mass hierarchy in the supersymmetric composite model is proposed. The source of the hierarchy is the kinetic-term mixing between composite quarks. Such mixing can be expected, if quarks are composite particles. A model in which the mechanism works is constructed, although it is not perfectly realistic because of some assumptions and unnaturalness.

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arXiv1998

Towards Deriving Higgs Lagrangian from Gauge Theories

A new method of deriving the Higgs Lagrangian from vector-like gauge theories is explored. After performing a supersymmetric extension of gauge theories we identify the auxiliary field associated with the "meson" superfield, in the low energy effective theory, as the composite Higgs field. The auxiliary field, at tree level, has a "negative squared mass". By computing the one-loop effective action in the low energy effective theory, we show that a kinetic term for the auxiliary field emerges when an explicit non-perturbative mechanism for supersymmetry breaking is introduced. We find that, due to the naive choice of the Kaehler potential, the Higgs potential remains unbounded from the below. A possible scenario for solving this problem is presented. It is also shown that once chiral symmetry is spontaneously broken via a non-zero vacuum expectation value of the Higgs field, the low energy composite fermion field acquires a mass and decouples, while in the supersymmetric limit it was kept massless by the 't Hooft anomaly matching conditions.

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arXiv1997

Mass Generation Mechanism in Supersymmetric Composite Model with Three Generations

We propose a supersymmetric composite model with three generations in which supersymmetry and electroweak symmetry are broken dynamically, and masses of quarks and leptons are generated without introducing any mass scales by hand. All the mass scales in the model are expected to be generated dynamically. The mechanism to have mass hierarchy is explicitly described, although the roughly estimated mass spectrum of quarks and leptons does not exactly coincide with the realistic one.

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arXiv1997

A Supersymmetric Composite Model with Dynamical Supersymmetry Breaking

We present a supersymmetric composite model with dynamical supersymmetry breaking. The model is based on the gauge group $SU(2)_S \times SU(2)_H \times SU(3)_c \times SU(2)_L \times U(1)_Y$. Supersymmetry is dynamically broken by the non-perturbative effect of the $SU(2)_S$ `supercolor' interaction. The large top Yukawa coupling is naturally generated by the $SU(2)_H$ `hypercolor' interaction as recently proposed by Nelson and Strassler. The supersymmetry breaking is mediated to the standard model sector by a new mechanism. The electroweak symmetry breaking is caused by the radiative correction due to the large top Yukawa coupling with the supersymmetry breaking. This is the `radiative breaking scenario', which originates from the dynamics of the supercolor and hypercolor gauge interactions.

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arXiv1997

An Analysis on a Supersymmetric Chiral Gauge Theory with No Flat Direction

A guiding principle to determine the Kaehler potential in the low energy effective theory of the supersymmetric chiral gauge theory with no flat direction is proposed. The guiding principle is applied to the SU(5) gauge theory with chiral superfields in the 5* and 10 representation, and the low energy effective theory is consistently constructed. The spontaneous supersymmetry breaking takes place in the low energy effective theory as expected. The particle mass spectrum in the low energy is explicitly calculated.

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