International Journal of Modern Physics A

A twistor framework for foundations of physics is outlined, in which (1) spacetime is secondary, derived from twistor constructions; (2) the primary physical agents are described by elements of sheaf cohomology defined on twistor space, which encode all information about the spacetime entities (fields and particles); (3) the dynamics of spacetime entities is encoded in the holomorphic structures of twistor space and revealed through Penrose transform and its generalizations (twistor diagrams); (4) the nonlinearity of gravity and nonabelian gauge interactions is a manifestation of the deformation of twistor space effected by the self-interacting twistor agents. A consistent framework of quantum gravity is attainable within twistor formalism because not only can gravity be derived from the primary physical agents of the formalism but also, and most importantly, the formalism itself can be proven intrinsically quantal without the necessity of imposing a quantum postulate upon it extrinsically through a quantization procedure. Indeed, the Planck constant and the whole quantum edifice built thereupon can be derived from formalism. Thus, the conflicts between the principles of general relativity and quantum theory are dissolved because both theories are consequences of twistor formalism, and the century-long debate concerning the possibility of a consistent framework of quantum gravity is closed. Many technical and conceptual issues must be clarified before the twistor formalism can be turned into a practical research framework. But the foundational pillars of the framework provided by twistor formalism are rock solid.

This paper explores the experimental search potential for sbottom pair production in an R-parity conserving scenario at the LHC Run-3 and HL-LHC. The sbottom decays with a 100% BR via a chargino, ${\tilde{b}}_1\to t{\tilde{\chi }}_1^{\pm }$, which subsequently decays to a W boson and a neutralino, ${\tilde{\chi }}_1^{\pm }\to W{\tilde{\chi }}_1^0$, also with a 100% BR. The study follows the ATLAS object definitions and event selection criteria from [ATLAS Collab., J. High Energy Phys. 06, 046 (2020), arXiv:1909.08457 [hep-ex]], focusing on Rpc2L1b and Rpc2L2b signal regions defined with same-sign leptons and at least one b-tagged jet. Projected exclusion limits are presented in the ${\tilde{b}}_1$–${\tilde{\chi }}_1^0$ mass plane for three center-of-mass energies (13, 13.6 and 14TeV) and three integrated luminosity scenarios (139, 300 and 3000fb${}^{-1}$).

This paper examines the Standard Model under the strong–electroweak symmetry group $S{U}_S(3)\times U_{\mathit{\text{EW}}}(2)$ subject to the Lie algebra condition ${\text{𝔲}}_{\mathit{\text{EW}}}(2)\ncong {\text{𝔰}\text{𝔲}}_I(2)\oplus {\text{𝔲}}_Y(1)$. Physically, the condition ensures that all electroweak gauge bosons interact with each other prior to symmetry breaking — as one might expect from $U(2)$ invariance. This represents a crucial shift in the identification of physical gauge bosons: Unlike the Standard Model which posits a change of Lie algebra basis induced by spontaneous symmetry breaking, here the basis is unaltered and A, $Z^0$, $W^{\pm }$ represent the physical bosons both before and after spontaneous symmetry breaking.

Our choice of ${\text{𝔲}}_{\mathit{\text{EW}}}(2)$ requires some modification of the matter field representation of the Standard Model. The group $U_{\mathit{\text{EW}}}(2)$ admits two pertinent defining representations, $2$ and its $U(2)$-conjugate $2^c$, related by a large gauge transformation. Accordingly, the product group structure calls for strong–electroweak degrees of freedom in the $(3,2)$ and the $(3,2^c)$ of $S{U}_S(3)\times U_{\mathit{\text{EW}}}(2)$ that possess integer electric charge just like leptons. These degrees of freedom play the role of quarks, and they lead to a modified Lagrangian that nevertheless reproduces transition rates and cross-sections equivalent to the Standard Model. In particular, they reproduce the fractional electric charge of quark currents.

The close resemblance between quark and lepton electroweak doublets in this picture suggests a mechanism for a speculative phase transition between quarks and leptons that stems from the product structure of the symmetry group. Our hypothesis is that the strong and electroweak bosons see each other as a source of decoherence. In effect, lepton representations get identified with the $SU(3)$-trace-reduced quark representations. This mechanism allows for possible extensions of the Standard Model that do not require large inclusive multiplets of matter fields and might explain the Higgs as a pseudo Nambu–Goldstone boson.

Unifying the massive spin-1 field with gravity requires the implementation of a regular vector field that satisfies the spin-1 Proca equation and is a fundamental part of the space–time metric. That vector field is one of the pair of vectors in the line element field $(X,-X)$, which is paramount to the existence of all Lorentzian metrics and Modified General Relativity (MGR). Symmetrization of the spin-1 Klein–Gordon equation in a curved Lorentzian space–time introduces the Lie derivative of the metric along the flow of one of the regular vectors in the line element field. The Proca equation in curved space–time can then be described geometrically in terms of the line element vector, the Lie derivative of the Lorentzian metric and the Ricci tensor, which unifies gravity and the spin-1 field. Related issues concerning charge conservation and the Lorenz constraint, singularities in a spherically symmetric curved space–time and geometrical implications of MGR to quantum theory are discussed. A geometrical unification of gravity with quantum field theory is presented.

We find new classes of the dynamical black hole solutions in five- or higher-dimensional Einstein–Maxwell-dilaton theory, in which the dilaton field interacts nontrivially with the Maxwell field, and the cosmological constant, with two arbitrary coupling constants. The solutions which are nonstationary, and almost conformally regular everywhere, are constructed by embedding the four-dimensional self-dual geometries. We consider three different situations, where the two coupling constants are not equal, are nonzero equal and finally both are zero. We also consider the cases where one of the metric functions, depends on one coordinate only, and another interesting case where it depends on two spatial coordinates. We also find that the cosmological constant can take all possible negative, zero and positive values, hence our solutions are asymptotically anti-de Sitter, flat and de Sitter. We discuss the properties of the solutions which are the analytic description of coalescing black holes in any dimensions, greater or equal to five.

Recently, the Rastall–Rainbow gravity emerged as an intriguing modified gravity theory. This theory is a combination of two theories, namely, the Rastall theory and the Rainbow description. This study aims to investigate the potential existence of static, spherically symmetric wormholes in this gravity theory. Specifically, we provide precise solutions to asymptotically flat wormhole geometries for the specific choice of the redshift and shape functions. With the specific examples, we investigate some issues concerning energy conditions and adiabatic sound velocity. We also consider the “volume integral quantifier” to assess the total amount of energy-condition violation matter. Finally, we conclude that reducing Rastall’s parameters and adjusting the Rainbow functions may alleviate the violation of energy conditions.

A generalization at finite temperature of the scalar Myers–Pospelov quantum field theory with mass dimension five operators that break Lorentz symmetry is considered. In particular, we introduce a thermal vacuum and a doubled Hilbert space within the formalism of Thermo Field Dynamics (TFD) to account for extended quantum field effects. The higher-order operators in the effective Lagrangian give rise to negative-metric modes, which are treated using a perturbative method. The perturbative modes that propagate correspond to standard second-order equations of motion with Lorentz-violating modifications without altering the number of degrees of freedom. In this perturbative, Lorentz-violating TFD framework, we investigate the finite-temperature effects, including thermal fluctuations and size effects.

The gradient flow scheme has emerged as a prominent nonperturbative renormalization scheme on the lattice, where flow time is introduced to define the renormalization scale. In this study, we perturbatively compute the gradient flow coupling for the SU(N) Yang–Mills theory in the large-N limit in terms of the lattice bare coupling up to three-loop order. This is achieved by combining the twisted Eguchi–Kawai model with the numerical stochastic perturbation theory. We analyze the flow time dependence of the perturbative coefficients to determine the perturbative beta function coefficients, successfully computing the one-loop coefficient in the large-N limit using three matrix sizes $N=289,441,529$. However, the higher-order coefficients are affected by large statistical errors. We also explore the potential for reducing these statistical errors through variance reduction combined with the large-N factorization property of the SU(N) Yang–Mills theory, and estimate the required number of samples for the precise determination of the higher-order coefficients.

This paper presents a study on the valence parton distribution functions (PDFs) of the pion and the kaon, which plays a crucial role in understanding the structure and interactions of hadrons. The study utilizes the valon model, which assumes that each hadron consists of two or three valence quarks, each carrying a fraction of the hadron’s momentum. The valence PDFs of the pion and the kaon are calculated at a low initial scale and then evolved to higher scales using the QCD and the QED $\otimes$ QCD Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equations in Mellin space. A comparison is made between the obtained results and other theoretical and experimental data, demonstrating the predictive power of our approach for the pion and kaon PDFs in the context of the large hadron collider (LHC) as well. Furthermore, it is discovered that the pion valence PDFs moments agree with other phenomenological methods at different scales, indicating the consistency and reliability of our method.