International Journal of Modern Physics A

In this paper, we reinvestigate a two-matrix model with three sets of coupling constants and derive two series of constraints. One series of the constraint operators yield the exact $W_{1+\infty }$ algebra. Other constraints are derived from the higher-order total derivatives which are associated with the free fermion point of the Calogero system. We further construct the two-supereigenvalue models and derive their super-Virasoro constraints.

In this paper, we explore the parameter space for processes with fermionic flavor violation within the Two Higgs Doublets Model (2HDM) type III, processes of Flavor Changing Neutral Currents (FCNCs) are present at Leading Order (LO) as dynamics beyond the Standard Model (SM) are included. We analyze the possible Yukawa couplings beyond the SM involving the quark top, as the experimental signatures would be a clear signal to conclude about the model. The processes we analyzed are same sign top pair production at the $pp$ collisions, and single top quark production in $ep$ collisions, through Deep Inelastic Scattering (DIS). To examine the scenarios that could exhibit such exotic events, we perform a scan in the parameter space to determine the observation possibilities for FCNC. We show the results considering the model parameters, coming from modified Yukawa interactions, $|{\tilde{\chi }}_{ij}^f|$ of the order one. In addition, we explore the order of magnitude of possible single top production via $\mu p$, at the proposed muon–proton collider. We found scattering values for these exotic processes of up to $\mathcal{𝒪}(10^{-2})pb$.

In this paper, we study the inclusive photoproduction of $T_{\bar{c}\bar{c}}{(3875)}^{-}$ mesons (which are the antiparticles of the doubly charmed tetraquarks $T_{cc}{(3875)}^{+}$ discovered recently by the LHCb Collaboration) from nuclei in the near-threshold energy region within the nuclear spectral function approach by considering incoherent direct ($\gamma p(n)\to D^{+}(D^0)T_{\bar{c}\bar{c}}{(3875)}^{-}{\mathrm{\Lambda }}_c^{+}$) photon–nucleon $T_{\bar{c}\bar{c}}{(3875)}^{-}$ creation processes as well as five possible different scenarios for their internal structure with the main goal of clarifying the possibility to decipher this structure (and, hence, that of $T_{cc}{(3875)}^{+}$) in photoproduction via integral and differential observables. We calculate the absolute and relative excitation functions for $T_{\bar{c}\bar{c}}{(3875)}^{-}$ production off ${}^{12}$C and ${}^{184}$W target nuclei at near-threshold photon beam energies of 30–38 GeV, the absolute differential cross-sections for their production off these target nuclei at laboratory polar angles of 0°–10° as well as the A and momentum dependences of the relative (transparency ratios) cross-sections for $T_{\bar{c}\bar{c}}{(3875)}^{-}$ production at photon energy of 35GeV within the adopted scenarios for the $T_{\bar{c}\bar{c}}{(3875)}^{-}$ meson intrinsic structure. We demonstrate that the absolute and relative observables considered show a certain sensitivity to these scenarios. Therefore, the measurement of such observables in future experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the US and China in the near-threshold energy region might shed light on the $T_{cc}{(3875)}^{+}$ internal structure.

In this paper, we investigate a $4\mathrm{\text{D}}$ solution of Einstein field equations, an extension of $2\mathrm{\text{D}}$ Misner space in the context of Ricci-inverse ($\mathcal{ℛ}\mathcal{ℐ}$)-gravity theory. For that, we consider two different class, namely, Class-II model which is defined by the function $f(\mathcal{ℛ},A^{\mu \nu }{A}_{\mu \nu })$ and Class-III model defined by the function $f(\mathcal{ℛ},\mathcal{𝒜},A^{\mu \nu }{A}_{\mu \nu })$. Here, $A^{\mu \nu }$ is the anti-curvature tensor with $\mathcal{𝒜}$ as its scalar, and $\mathcal{ℛ}$ is the Ricci scalar. Using this $4D$ metric as background, the modified field equations for Ricci-inverse gravity were derived and obtain the results. These derived field equations are then solvable by choosing the pure radiation field as the energy-momentum tensor, including a cosmological constant as does in the general relativity. This implies that the chosen $4\mathrm{\text{D}}$ space-time is a valid solution in this novel gravity theory, and thereby violate the causality condition, analogous to general relativity.

In this paper, we explore the relativistic quantum dynamics of spin-0 oscillator fields within the framework of a rotating cosmic string space–time, taking into account the presence of scalar and vector potentials. We solve the Klein–Gordon oscillator equation in this curved space–time, incorporating generalized versions of the Yukawa and Hulthen potentials as vector and scalar potentials, respectively. The analytical solution of the quantum system yields the energy eigenvalue and corresponding eigenfunction, which is expressed in terms of confluent Heun functions. The resulting energy spectrum is shown to depend on various parameters associated with the cosmic string space–time and the confining potentials. We graphically illustrate how the energy spectrum varies with changes in both the potential parameters and the cosmic string parameters.

This paper responds to suggestions that the standard approach to collective neutrino oscillations leaves out potentially important quantum many-body correlations. Arguments in favor of this idea have been based on calculations that, on close scrutiny, offer no evidence either way. Inadequacies of the usual quantum-kinetic formalism are not currently supported by the literature.

In this paper, we explore a modified black brane within AdS space–time, characterized by the Lagrangian density $\frac{1}{q}\mathrm{\text{arcsin}}(qR)-2\mathrm{\Lambda }$. Due to the absence of an analytic solution, we approach the Einstein equations using a perturbative method, extending our analysis to the second order in q. Subsequently, we compute the ratio of shear viscosity to entropy density. Our results suggest that the KSS Bound is not saturated in this model.