arXiv subjects

Zainul Abidin

Publications and source records attributed to Zainul Abidin.

11 recordsLinked to original sources

arXiv2024

Playing Lato-lato is Difficult and This is Why

Lato-lato, a pendulum-based toy gaining popularity in Indonesian playgrounds, has sparked interest with competitions centered around maintaining its oscillatory motion. While some find it easy to play, the challenge lies in sustaining the oscillation, particularly in maintaining both "up and down collisions." Through a Newtonian dynamics numerical analysis using Python (code by ChatGPT), this study identifies two equilibrium phases - phase 1, characterized by normal pendulum motion, and phase 2, the double collision mode - by using the driven oscillation model. In addition, further analysis and discussion are done using the obtained numeric data. The difficulty in remaining in phase 2 highlights the intricate hand-eye coordination required, shedding light on the toy's appeal and the skill it demands.

physics.class-ph↗

arXiv2019

Kaon form factor in holographic QCD

The kaon form factor in the spacelike region is calculated using a holographic QCD model with the "bottom-up" approach. We found that our result for the kaon form factor in low $Q^2$ has a remarkable agreement with the existing data, where $Q^2$ is the four-momentum transfer squared. The charge radius of the kaon, as well as the kaon decay constant, are found to be in a good agreement with the experiment data. We then predict the kaon form factor in the asymptotic region (larger $Q^2$) showing $1/Q^2$ behavior, which is consistent with the perturbative QCD prediction.

hep-ph↗

arXiv2018

Superconducting vortex in a deconstructed holographic model

A deconstructed holographic model for an $s$-wave superconductor in $2+1$ dimensions has been proposed in the literature. Here, we consider solutions in the presence of perpendicular magnetic fields, where vortex formed. We calculate the expectation value of the Cooper pair condensate as a function of radial distance from the center of the vortex for different numbers of lattice points.

hep-th↗

arXiv2011

Asymptotic Freedom in Holographic QCD

We calculate the running of the quark mass and the quark condensate using a dynamical soft-wall model by Csaki and Reece. We show that a correct running can be obtained with an appropriate sign for the dilaton field. In the soft-wall model with quadratic dilaton profile, a wrong sign for the dilaton field can give rise to a massless vector meson, a signature of spontaneously broken symmetry in the vector sector, which is not observed in nature. With a right parameter range, we obtain no such massless vector meson. We also find that, contrary to the soft-wall model with quadratic dilaton profile, the model allows a non-vanishing quark condensate in the chiral limit. We obtain the vector meson mass spectrum similar to that of the hard-wall model. By varying a parameter in the model we can fit the running of the quark mass and of the quark condensate.

hep-ph↗

arXiv2010

Positron production scenarios and the angular profile of the galactic center 511-keV line

The observed angular profile of the 511-keV photon excess from the Milky Way galactic center can allow us to select among combinations of various dark matter and other positron production mechanisms with various models for the dark matter distribution. We find that a relic decay scenario gives too flat an angular distribution for any dark matter distribution in our survey, but that a dark matter-dark matter collisional scenario, or a scenario that involves particles emitted from a localized central source producing positrons some distance out, can match the observed galactic center angular profile if the dark matter distribution is neither too flat nor too cuspy. Additionally, positron migration or diffusion before annihilation broadens the angular profile to an extent that an average migration of more than half a kiloparsec is not viable with most dark matter distributions. The observed angular profile is also consistent with the occurrence of transient events in the past, followed by isotropic positron diffusion.

hep-ph↗

arXiv2009

Strange mesons and kaon-to-pion transition form factors from holography

We present a calculation of the $K_{\ell 3}$ transition form factors using the AdS/QCD correspondence. We also solidify and extend our ability to calculate quantities in the flavor-broken versions of AdS/QCD. The normalization of the form factors is a crucial ingredient for extracting $|V_{us}|$ from data, and the results obtained here agree well with results from chiral perturbation theory and lattice gauge theory. The slopes and curvature of the form factors agree well with the data, and with what results are available from other methods of calculation.

hep-ph↗

arXiv2009

Nucleon electromagnetic and gravitational form factors from holography

The electromagnetic form factors of nucleons are calculated using an AdS/QCD model by considering a Dirac field coupled to a vector field in the 5-dimensional AdS space. We also calculate a gravitational or energy-momentum form factor by perturbing the metric from the static AdS solution. We consider both the hard-wall model where the AdS geometry is cutoff at z_0 and the soft-wall model where the geometry is smoothly cut off by a background dilaton field.

hep-ph↗

arXiv2008

Hadronic Momentum Densities in the Transverse Plane

We examine the spatial density within extended objects of the momentum component $p^+$, and find relativistically exact connections to Fourier transforms of gravitational form factors. We apply these results to obtain semi-empirical momentum density distributions within nucleons, and similar distributions for spin-1 objects based on theoretical results from the AdS/QCD correspondence. We find that the momentum density in the transverse plane is more compact than the charge density.

hep-ph↗

arXiv2008

Gravitational Form Factors in the Axial Sector from an AdS/QCD Model

We calculate the stress tensor, or energy-momentum tensor, form factors of the pion and of axial vector mesons in the chiral limit of a hard wall AdS/CFT model of QCD. One (of the two) pion gravitational form factors is directly related to the second moment of the pion generalized parton distribution, thus providing a sum rule for the latter. As was also the case for vector mesons, both the pion and the axial vector mesons appear strikingly more compact measured by the gravitational form factor than by the electromagnetic form factor.

hep-ph↗

arXiv2008

Gravitational Form Factors of Vector Mesons in an AdS/QCD Model

We calculate gravitational form factors of vector mesons using a holographic model of QCD. These provide restrictions on the generalized parton distributions of vector mesons, via the sum rules connecting stress tensor form factors to GPDs. We concentrate on the traceless part of the stress tensor, which suffices to fix the momentum and angular momentum sum rules. The vector mesons appear noticeably more compact measured by the gravitational form factors than by the charge form factor.

hep-ph↗

arXiv2007

Rosenbluth Nonlinearity from Two-Photon Exchange

We calculate, using a generalized parton distribution based formalism, the nonlinearity of the Rosenbluth plots that arise from hard two-photon exchange corrections that are not included in the classic calculations of the radiative corrections to electron-proton elastic scattering.

hep-ph↗