Nuclear Physics B最新文献

It is known that the formation of a wormhole typically involves a violation of the Weak Energy Condition (WEC), but the reverse is not necessarily true. In the context of Brans-Dicke gravity, the generalized Campanelli-Lousto solution, which we shall unveil in this paper, demonstrates a WEC violation that coincides with the appearance of unbounded sheets of spacetime within the region where $0<r<r_{\text{s}}$. The emergence of a wormhole in the region where $r>r_{\text{s}}$ is thus only an indirect consequence of the WEC violation. Whereas the two regions, $0<r<r_{\text{s}}$ and $r>r_{\text{s}}$, in general are disconnected by physical singularities at $r=r_{\text{s}}$, they are both part of the same mathematical solution, and their behavior can provide insights into the WEC, which is a mathematical property of the solution. Furthermore, we utilize the generalized Campanelli-Lousto solution to construct a Kruskal-Szekeres diagram, which exhibits a “gulf” sandwiched between the four quadrants in the diagram, a novel feature in Brans-Dicke gravity. Overall, our findings shed new light onto a complex interplay between the WEC and wormholes in the Brans-Dicke theory.

In this paper, we study the thermodynamic properties and stability of static charged BTZ black holes with the inclusion of higher-order quantum corrections. The corrections to the entropy, mass, and Helmholtz free energy are derived, revealing the intricate interplay between quantum effects and classical gravitational forces in the context of black hole thermodynamics. The study of the specific heat capacity shows that higher-order corrections stabilize the system by removing the instabilities present at lower orders. The analysis of the van der Waals-like isotherms demonstrates the continuous transition from a highly compressible to an almost incompressible regime as the volume is decreased, akin to the behavior of supercritical fluids. Notably, the isotherms do not exhibit any regions of negative compressibility, indicating the absence of instabilities. Furthermore, the convexity of the Helmholtz free energy as a function of volume confirms the stability of the charged BTZ black hole system. These findings provide valuable insights into the complex thermodynamic landscape of three-dimensional black holes and the role of quantum corrections in shaping their behavior.

We construct an integrable sigma model with a generalized $F$ structure, which involves a generalized Nijenhuis structure $J$ satisfying $J^3=-J$. Utilizing the expression of the generalized complex structure on the metric Lie group manifold G in terms of operator relations on its Lie algebra $g$, we formulate a Yang-Baxter sigma model with a generalized complex structure. Additionally, we present multi-Yang-Baxter sigma models featuring two and three compatible Nijenhuis structures. Examples for each of these models are provided.

Bethe Ansatz was discovered in 1932. Half a century later its algebraic structure was unearthed: Yang-Baxter equation was discovered, as well as its multidimensional generalizations [tetrahedron equation and d-simplex equations]. Here we describe a universal method to solve these equations using Clifford algebras. The Yang-Baxter equation ($d=2$), Zamolodchikov's tetrahedron equation ($d=3$) and the Bazhanov-Stroganov equation ($d=4$) are special cases. Our solutions form a linear space. This helps us to include spectral parameters. Potential applications are discussed.

In a framework of the Standard Model (SM) simply extended by an SU(2) doublet $(X,T)$ including a vectorlike X-quark (VLQ-X), with electric charge $\left|Q_X\right|=5/3$, we investigate the single production of the VLQ-X induced by the couplings between the VLQ-X with the first and the third generation quarks at the Large Hadron Collider (LHC) operating at $\sqrt{s}=14$ TeV. The signal is searched in events including same-sign dileptons (electrons or muons), one b-tagged jet and missing energy, where the X quark is assumed to decay into a top quark and a W boson, both decaying leptonically. After a rapid simulation of signal and background events, the 95% CL exclusion limits and the 5σ discovery reach are respectively obtained at the LHC with an integrated luminosity of 300 and 3000 fb⁻¹, respectively.

In the present work, we construct the diquark-antidiquark type four-quark currents to investigate the mass spectrum of the ground state hidden-charm-hidden-strange tetraquark states with the quantum numbers $J^{PC}=0^{++}$, $1^{+-}$, $1^{++}$ and $2^{++}$ via the traditional QCD sum rules in a comprehensive way. We update old calculations, perform new calculations and analysis in a rigorous way, and take account of the net light-flavor $SU\left(3\right)$ breaking effects in a consistent way. And we make more reasonable identifications for the $X\left(3960\right)$, $X\left(4140\right)$, $X\left(4274\right)$, $X\left(4500\right)$, $X\left(4685\right)$ and $X\left(4700\right)$ and supersede some old identifications. Furthermore, we consider our previous theoretical predictions, and make reasonable/suitable identifications of the new LHCb states $h_c\left(4000\right)$ and ${\chi }_{c1}\left(4010\right)$.

We present a Dirac mass model based on $A_4$ modular symmetry within Type-I seesaw framework. This extension of Standard Model requires three right-handed neutrinos and three heavy Dirac fermions superfields, all singlet under $SU{\left(2\right)}_L$ symmetry. The scalar sector is extended by the inclusion of a $SU{\left(2\right)}_L$ singlet superfield, χ. Here, the modular symmetry plays a crucial role as the Yukawa couplings acquire modular forms, which are expressed in terms of Dedekind eta function $\eta \left(\tau \right)$. Therefore, the Yukawa couplings follow transformations akin to other matter fields, thereby obviating the necessity of additional flavon fields. The acquisition of vev by complex modulus τ leads to the breaking of $A_4$ modular symmetry. We have obtained predictions on neutrino oscillation parameters, for example, the normal hierarchy for the neutrino mass spectrum. Furthermore, we find that heavy Dirac fermions, in our model, can decay to produce observed baryon asymmetry of the Universe through Dirac leptogenesis.

In this paper, an effective Lagrangian of an itinerant electron system of finite density at a finite magnetic field is obtained. It includes a Chern-Simons term of electromagnetic potentials of lower-scale dimensions compared to those studied before. This term has an origin in the many-body wave function and a unique topological property that is independent of a spin degree of freedom. The coupling strength is proportional to $\frac{\rho }{eB}$, which is singular at $B=0$ for a constant charge density. The effective Lagrangian at a finite B represents the physical effects at $B\ne 0$ properly. A universal shift of the magnetic field known as the Slater-Pauling curve is obtained from the effective Lagrangian.

Modifications of Dirac operators in supergravity flux backgrounds are considered. Modified spin curvature operators and squares of modified Dirac operators corresponding to Schrödinger-Lichnerowicz-like formulas are obtained for different types of flux modifications. Symmetry operators of modified massless and massive Dirac equations are found in terms of modified Killing-Yano and modified conformal Killing-Yano forms. Extra constraints for symmetry operators in terms of different types of fluxes and modified Killing-Yano forms are determined.