abstract

The potential of triphoton production to obtain limits on anomalous Higgs boson couplings at \(H\gamma \gamma \) and \(HZ\gamma \) vertices is studied in the Standard Model Effective Field Theory (EFT) framework for the post-LHC circular high-energy hadron colliders: High Luminosity-LHC (HL-LHC), High-Energy LHC (HE-LHC), and Low-Energy FCC (LE-FCC) which are designed with standard configurations of 14 TeV/3 ab\(^{-1}\), 27 TeV/15 ab\(^{-1}\), and 37.5 TeV/15 ab\(^{-1}\). Madgraph in which the effective Lagrangian of the SM EFT is implemented using FeynRules and UFO framework is used to generate both background and signal events. These events are then passed through PYTHIA 8 for parton showering and Delphes to include realistic detector effects. After optimizing cuts on kinematics of three photons as well as the reconstructed invariant mass of the two leading photons, invariant mass of three leading photons is used to obtain constraints on the Wilson coefficients of dimension-six operators. We report on the result of a two-dimensional scan of \(\bar {c}_{\gamma }\) and \(\tilde {c}_{\gamma }\) couplings at 95% confidence level and compare with the LHC results. Our obtained limits without systematic error on \(\bar {c}_{\gamma }\) ( \(\tilde {c}_{\gamma }\)) are \([-3.15;1.41]\times 10^{-2}\) (\([-2.12;2.12]\times 10^{-2}\)), \([-1.21;0.78]\times 10^{-2}\) (\([-0.98;0.98]\times 10^{-2}\)), and \([-0.89;0.66]\times 10^{-2}\) (\([-0.77;0.77]\times 10^{-2}\)) for HL-LHC, HE-LHC, and LE-FCC, respectively.

abstract

We derive a formula that defines quantum fluctuations of energy in subsystems of a hot relativistic gas. For small subsystem sizes, we find a substantial increase of fluctuations compared to those known from the standard thermodynamic considerations. However, if the size of the subsystem is sufficiently large, we reproduce the result for energy fluctuations in the canonical ensemble. Our results are subsequently used in the context of relativistic heavy-ion collisions to introduce limitations of the concepts such as classical energy density or fluid element. In a straightforward way, our formula can be applied in other fields of physics, wherever one deals with hot and relativistic matter.

abstract

We numerically study the classical evolution of a Yang–Mills matrix model with two distinct mass deformation terms, which can be contemplated as a massive deformation of the bosonic part of the BFSS model. Through numerical analysis, it is shown that when the simulations are started from a certain set of initial conditions, thermalization occurs. Besides, an estimation method is proposed to determine the approximate thermalization time. Using this method, we demonstrate that thermalization time varies logarithmically with increasing matrix size when the mass terms differ. Introducing a matrix configuration, we also obtain reduced actions and subsequently analyze how the thermalization time changes as a function of energy.

abstract

The electric quadrupole moments of a number of iron isotopes Fe (\(Z=26\), \(A=53\), 54, 55, 56, 57, 58, and 59) were calculated using \(fp\)-shell. The shell-model calculations were performed using two effective interactions (KB3 and FPD6). The NuShellX@MSU code is used to calculate the one-body density matrix (OBDM). Calculations of quadrupole moments (QM) were performed by measuring the core-polarization (CP) effects that compensate for the discarded space outside the model space and approximate it using the nucleon effective charges. The group of effective charges such as the conventional effective charges (\(e_p = 1.3\) \(e\), \(e_n = 0.5\) \(e\)) (Con), the Bohr–Mottelson (B–M) effective charges that were deduced for each isotope, the standard effective charges (\(e_p = 1.36\) \(e\), \(e_n = 0.45\) \(e\)) (St), and the effective charges from the NushellX program (\(e_p = 1.5\) \(e\), \(e_n = 0.5\) \(e\)) (Ns) were used in the calculations in addition to one proposed set of effective charges that take values Eff.1 (\(e_p= 1.0\) \(e\), \(e_n= 0.0\) \(e\)). Results have shown that using the KB3 interaction to calculate the electric quadrupole moments of various isotopes of Fe is better than using the FPD6 interaction. When using an empirical effective charge (\(e_p=1\)), the quadrupole moments calculations (theoretical) results were far from the experimental values. Finally, the collapse in the magicity property of isotope \(^{54}\)Fe which has 28 neutrons (where \(N=28\) is a magic number) has also been verified.

abstract

The phenomena of shape evolution and shape coexistence are studied in even–even \(^{86-134}\)Pd isotopes by employing the relativistic Hartree–Bogoliubov (RHB) model by employing density-dependent point-coupling parameter sets DD-PC1 and DD-PCX with separable pairing interaction. Our findings of binding energies, quadrupole deformation parameter, charge radii, and two-neutron separation energies as a function of neutron number \(N\) are compared with available experimental data and various theoretical models. Our theoretical results predict prolate–oblate shape coexistence in \(^{108}\)Pd isotope.

abstract

We review a procedure of factorizing the Minkowski space Dirac equation over a suitable superspace, discuss its Euclidean space version and apply the worked out formalism in the case of an almost-commutative Dirac operator. The presented framework is an attempt to reconcile non-commutative geometry and supersymmetry.

abstract

We show that solutions exist to a simplified version of the system of equations obtained by coupling Bray’s conformal flow of metrics and the generalised Jang equation. This would establish the Penrose inequality for a class of conformally flat perturbations of Schwarzschild spacetime, provided that one can additionally prove that existence of a suitable approximate solution to the Jang equation implies the Penrose inequality.