International Journal of Modern Physics A

$f(Q,T)$ gravity is a novel extension of the symmetric teleparallel gravity where the Lagrangian $L$ is represented through an arbitrary function of the nonmetricity $Q$ and the trace of the energy–momentum tensor $T$.²³ In this work, we have constrained a widely used $f(Q,T)$ gravity model of the form $f(Q,T)=Q^{a+1}+bT$ from the primordial abundances of the light elements to understand its viability in cosmology. We report that the $f(Q,T)$ gravity model can elegantly explain the observed abundances of Helium and Deuterium while the Lithium problem persists. From the constraint on the expansion factor in the range $0.9425\lesssim Z\lesssim 1.1525$, we report strict constraints on the parameters $a$ and $b$ in the range $0.01\lesssim a\lesssim -0.01$ and $-5.86\lesssim b\lesssim 12.52$, respectively.

In this work, we have studied neutrinoless double beta decay (NDBD) and charged lepton flavor violation (CLFV) in a generic left–right symmetric model (LRSM). In this framework, type-I and type-II seesaw terms arise naturally. We have used $A_4\times Z_2$ discrete flavor symmetry to realize the LRSM. Within the model, we have considered type-I and type-II dominant cases and analyzed the new physics contributions to the NDBD process coming from different particles of LRSM. We tried to find the leading-order contributions to NDBD in type-I and type-II seesaw along with the decay rate of the process in our work. We have also studied different charged lepton flavor violating processes such as $\mu \to 3e$ and $\mu \to e\gamma$ and correlated with neutrino mass within the model.

In this paper, we investigate Einstein’s gravity induced from higher-derivative scalar field theories. We develop an approach utilizing an effective theory of multiple fields for the higher-derivative theory. The expressions for induced cosmological constant and the induced gravitational constant are obtained in the present scenario of induced gravity in $D$ dimensions. We also show that finite values for the induced constants can be extracted in certain infinite-derivative theories.

Following a modest comparison between canonical and affine quantization, which points to positive features in the affine procedures. We prove through Monte Carlo analysis that the covariant Euclidean scalar field theory, ${\phi }_n^r$, where $r$ denotes the power of the interaction term and $n=s+1$ where $s$ is the spatial dimension and 1 adds imaginary time, such that $r=n=4$ can be acceptably quantized using scaled affine quantization and the resulting theory is nontrivial, unlike what happens using canonical quantization.

We explore an $A_4$ flavor-based left–right symmetric model where neutrino masses and mixing are explained through linear seesaw mechanism. Taking $A_4$ flavor symmetry and left–right gauge symmetry together and adding a low-scale seesaw mechanism gives the advantage of (a) getting diagonal structures for both charged lepton mass matrix and Dirac neutrino mass matrix, (b) simpler relations among neutrino observables in the model and (c) large light-heavy neutrino mixing which gives dominant contributions to various lepton flavor violating decays like $\mu \to e\gamma$, $\mu \to eee$, $\mu \to e$. By saturating the experimental bounds on these decays we derive constraints on input model parameters and study analytically as well as numerically the correlation among model parameters and their dependence on experimentally determined neutrino parameters like ${𝜃}_{12}$, ${𝜃}_{23}$, ${𝜃}_{13}$, $\mathrm{\Delta }{m}_{\mathrm{\text{atm}}}^2$, $\mathrm{\Delta }{m}_{\mathrm{\text{sol}}}^2$. We also study CP-violation via Jarlskog invariants and show extra contributions to CP-violating effects that the model generates due to unitarity violation in the neutrino sector.

Quantum chromodynamics (QCD) is the theory of the strong interaction. The fundamental particles of QCD, quarks and gluons, carry color charge and form colorless bound states at low energies. The hadronic bound states of primary interest to us are mesons and baryons. A modern approach to computing hadron masses relies on the computationally intensive framework of lattice QCD. In cases where the exact quark composition or other quantum numbers of hadronic states are not precisely known, the prediction of masses from theoretical first principles is especially challenging. We address the problem of creating accurate and interpretable models of hadronic masses without resorting to extensive numerical computations. In this study, we construct a model of hadronic masses using both Bayesian and non-Bayesian techniques in machine learning. From knowledge of the meson spectrum only, neural networks and Gaussian processes predict the masses of baryons with 90.3% and 96.6% accuracy, respectively. We also predict the masses of pentaquarks and other exotic hadrons and demonstrate that machine learning is an effective tool for testing composition hypotheses. Our results surpass the benchmark constituent quark model both in terms of accuracy of predictions and hypothesis testing across all sectors of hadrons. We anticipate that our methods could yield a mass formula for hadrons from quark composition and other quantum numbers.

We describe a possible and alternative route to connect gravity with Elko theory. Our approach is based on the possibility to introduce a totally antisymmetric gauge field in the generalized Elko field equation, which is an alternative extension of the Dirac field equation. The corresponding totally antisymmetric field strength ($p$-form) is then associated with Grassmann–Plücker coordinates and therefore with a decomposable $p$-form. We show that such a totally antisymmetric field strength can be considered as the square root of the Riemann tensor associated to a homogeneous space. Motivated by this result we conjecture that a full connection with Riemann geometry and therefore with general relativity must be possible if such a field strength is not decomposable. We also show how a supergravity version could arise from a generalization of the above ideas.

In this paper, we investigate the influence of the background of a cosmic string space–time with a distortion of a radial line into a spiral on the interaction of the scalar field with a Cornell-type nonminimal coupling subject to a special static scalar potential. The special static scalar potential consists of radial oscillator harmonics potential and radial inverse-square potential. In order to study such a system based on the Katanaev–Volovich geometric approach, we acquire relativistic solutions corresponding to the generalized Klein–Gordon quantum oscillator for relativistic charged spin-zero boson particles using analytical methods in this background.