arXiv subjects

Seyed Mohsen Hosseini Nejad

Publications and source records attributed to Seyed Mohsen Hosseini Nejad.

16 recordsLinked to original sources

arXiv2026

Domain Structures and Static Potentials in $G_2$ Gauge Theory

We investigate the domain structures of the $G_2$ vacuum and the associated static potentials within the domain model, considering both zero and non-zero aggregate flux vacuum domains. Potentials associated with domains of zero aggregate flux exhibit favorable Casimir scaling and convexity properties at intermediate distances, and their long-range behavior matches the expected ordering of constant potential values according to representation. In contrast, potentials derived from domains with nonzero aggregate flux deviate from the key features of the confining force, as the absence of a minimal center-flux magnitude renders such configurations physically improbable. Furthermore, the potential ratios for $SU(3)$ and $SU(2)$ subgroups are found to be consistent with Casimir ratios of $G_2$ at intermediate regimes, suggesting a possible role for these subgroups in the confinement mechanism of the $G_2$ gauge group.

hep-ph↗

arXiv2024

Influence of center vortex interactions on the static potentials

We analyze the static potentials induced by vacuum domains for various representations in SU($4$) Yang-Mills theory within the framework of the domain structure model. By studying the interactions within the vacuum domains, we can uncover fundamental properties of the static potentials. It appears that attractions within the vacuum domains strongly adhere to Casimir scaling at intermediate distances. Conversely, the repulsions within the vacuum domains may decompose them into center vortices with the lowest magnitude of center vortex fluxes, thereby exhibiting $N$-ality at asymptotic distances.

hep-ph↗

arXiv2023

Plane vortex pairs, colorful structures and low-lying Dirac modes

We investigate the influence of topological charges on non-stable zero and near-zero modes of the single uni-color plane vortex pairs. We combine the uni-color plane vortices with the spherical vortex and also construct the plane vortex pairs with two colorful vortices. The stability of zero and near-zero modes is analyzed where various boundary conditions for the fermions are checked. In addition, plane vortex pairs may show the role of the topological charges for changing the chirality of fermions. The results clearly indicate characteristic properties for spontaneous chiral symmetry breaking.

hep-lat↗

arXiv2020

Contributions of the Cartan generators in potentials between static sources

We investigate the contributions of the Cartan generators in the static potentials for various representations in the framework of the domain model of center vortices for SU(3) gauge theory. Using the center domains with the cores corresponding to only one Cartan generator H8, already given as a particular proposal, leads to some concavities in the potentials for higher representations. Furthermore, the string tension of the fundamental representation is the same at Casimir scaling and N-ality regimes. We add the contribution of the other Cartan generator H3 to the potentials and therefore these shortcomings can be eliminated. However, we discuss that at intermediate range of distances the potentials induced by only H8 agree with the Casimir scaling better than those corresponding to both Cartan generators.

hep-ph↗

arXiv2019

Domain structures and quark potentials in SU($3$) gauge theory

We analyze the static potentials for various representations in SU($3$) Yang-Mills theory within the framework of the domain model of center vortices. The influence of vortex interactions is investigated on the static potentials. We show that, by ad-hoc choosing the probability weights of the different vortex configurations contributing to the static potential, a phenomenologically satisfactory result for the different representations can be achieved. In particular including vacuum domains, a way to effectively parametrize vortex interactions, is crucial in obtaining an (almost) everywhere convex potential when interpolating between the short distances and the asymptotic regimes.

hep-ph↗

arXiv2019

Fractional topological charges and the lowest Dirac modes

We introduce vortex configurations with fractional topological charges where one unicolor or colorful intersection of two perpendicular vortex pairs contributes to the topological charge of the configurations. Using both, the overlap and asqtad staggered fermion formulations, the lowest modes of the Dirac operator on the noninteger $Q$ configurations are studied in the fundamental and adjoint representations. We analyze the behavior of the fundamental and adjoint fermions in the background of the topological charge contributions of $|Q|=0.5$.

hep-lat↗

arXiv2018

Combining the color structures and intersection points of thick center vortices and low-lying Dirac modes

We investigate several examples of Yang-Mills gauge configurations containing center vortex structures, including intersection points between vortices and nontrivial color structures residing on the vortex world-surfaces. Various topological charge contributions of the color structures and intersection points are studied in these configurations. Low-lying eigenmodes of the (overlap) Dirac operator in the presence of these vortex backgrounds are analyzed. The results indicate characteristic properties for spontaneous chiral symmetry breaking.

hep-lat↗

arXiv2017

Colorful vortex intersections in SU(2) lattice gauge theory and their influencs on chiral properties

We introduce topological non-trivial colorful regions around intersection points of two perpendicular vortex pairs and investigate their influence on topological charge density and eigenmodes of the Dirac operator. With increasing distance between the vortices the eigenvalues of the lowest modes decrease. We show that the maxima and minima of the chiral densities of the low modes follow mainly the distributions of the topological charge densities. The topological non-trivial color structures lead in some low modes to distinct peaks in the chiral densities. The other low modes reflect the topological charge densities of the intersection points.

hep-lat↗

arXiv2017

Correlations between Abelian Monopoles and center vortices

We study the correlations between center vortices and Abelian monopoles for SU($3$) gauge group. Combining fractional fluxes of monopoles, center vortex fluxes are constructed in the thick center vortex model. Calculating the potentials induced by fractional fluxes constructing the center vortex flux in a thick center vortex-like model and comparing with the potential induced by center vortices, we observe an attraction between fractional fluxes of monopoles constructing the center vortex flux. We conclude that the center vortex flux is stable, as expected. In addition, we show that adding a contribution of the monopole-antimonopole pairs in the potentials induced by center vortices ruins the Casimir scaling at intermediate regime.

hep-ph↗

arXiv2016

Monopole-center vortex chains in $SU(2)$ gauge theory

We study the relation between center vortex fluxes and monopole fluxes for $SU(2)$ gauge group in a model. This model is the same as thick center vortex model but we use monopole-antimonopole configurations instead of center vortices in the vacuum. Monopole-antimonopole configurations are line-like similar to center vortices. The group factor and potential for the fundamental representation of these configurations are studied and compared with those of center vortices. As a result, we obtain monopole-vortex chains which appear in lattice Monte Carlo simulations, as well. If these monopole-vortex chains intersect the large Wilson loop in two points, screening is observed for the potential in the fundamental representation at large distances and confinement is observed when one leg of the chain intersects the Wilson loop.

hep-ph↗

arXiv2015

Colorful plane vortices and Chiral Symmetry Breaking in $SU(2)$ Lattice Gauge Theory

We investigate plane vortices with color structure. The topological charge and gauge action of such colorful plane vortices are studied in the continuum and on the lattice. These configurations are vacuum to vacuum transitions changing the winding number between the two vacua, leading to a topological charge $Q=-1$ in the continuum. After growing temporal extent of these vortices, the lattice topological charge approaches $-1$ and the index theorem is fulfilled. We analyze the low lying modes of the overlap Dirac operator in the background of these colorful plane vortices and compare them with those of spherical vortices. They show characteristic properties for spontaneous chiral symmetry breaking.

hep-lat↗

arXiv2015

Center vortices as composites of monopole fluxes

We study the relation between the flux of a center vortex obtained from the center vortex model and the flux formed between monopoles obtained from the Abelian gauge fixing method. Motivated by the Monte Carlo simulations which have shown that almost all monopoles are sitting on the top of vortices, we construct the fluxes of center vortices for $SU(2)$ and $SU(3)$ gauge groups using fractional fluxes of monopoles. Then, we compute the potentials in the fundamental representation induced by center vortices and fractional fluxes of monopoles. We show that by combining the fractional fluxes of monopoles one can produce the center vortex fluxes for $SU(3)$ gauge group in a "center vortex model". Comparing the potentials, we conclude that the fractional fluxes of monopoles attract each other.

hep-ph↗

arXiv2015

Contributions of the center vortices and vacuum domain in potentials between static sources

In this paper, we study the role of the domain structure of the Yang Mills vacuum. The Casimir scaling and $N$-ality are investigated in the potentials between static sources in various representations for $SU(2)$ and $SU(3)$ gauge groups based on the domain structure model using square ansatz for angle $α_{C}(x)$. We also discuss about the contributions of the vacuum domain and center vortices in the static potentials. As a result, the potentials obtained from vacuum domains agree with Casimir scaling better than the ones obtained from center vortices. The reasons of these observations are investigated by studying the behavior of the potentials obtained from vacuum domains and center vortices and the properties of the group factors. Then, the vacuum domains in $SU(N)$ and $G(2)$ gauge groups are compared and we argue that the $G(2)$ vacuum is filled with center vortices of its subgroups.

hep-ph↗

arXiv2014

Role of the SU($2$) and SU($3$) subgroups in observing confinement in the G($2$) gauge group

Applying the domain model to the G($2$) gauge group and the thick center vortex model to the SU($2$) and SU($3$) subgroups of G($2$), we calculate the potentials between static sources, as well as some parameters of the vortex profile. Comparing the results obtained from G($2$) and its subgroups, we argue that SU($2$) and SU($3$) gauge groups have important roles in observing confinement in the G($2$) gauge group.

hep-ph↗

arXiv2012

Confinement in G(2) Gauge Theories Using Thick Center Vortex Model and domain structures

The thick center vortex model with the idea of using domain structures is used to calculate the potentials between two G(2) heavy sources in the fundamental, the adjoint and the 27 dimensional representations. The potentials are screened at large distances. This behavior is expected from the thick center vortex model since G(2) has only a trivial center element which makes no contribution to the average Wilson loop at the large distance regime. A linear potential is obtained at intermediate distances for all representations. This behavior can be explained by the thickness of the vortices (domains) and by defining a flux for the trivial center element of G(2). The role of the SU(3) subgroup of G(2) in the linear regime is also discussed. The string tensions are in rough agreement with the Casimir operators of the corresponding representations.

hep-ph↗

arXiv2010

Center vortex model and the G(2) gauge group

The thick center vortex model is applied to G(2) gauge group to obtain the potentials between static sources of the fundamental and adjoint representations. The group G(2) has only one trivial center element and therefore it does not have any vortices which are defined based on non trivial center elements. To obtain the potential from the thick center vortex model, the idea of the vacuum domain structure is used. The intermediate string tensions from this model are in rough agreement with the G(2) lattice results and the Casimir ratio. We argue that the SU(3) subgroup of G(2) may be responsible for the linear potential at the intermediate distances.

hep-ph↗