International Journal of Modern Physics A

Standard relativistic hydrodynamics has been successful in describing the properties of the strongly interacting matter produced in the heavy-ion collision experiments. Recently, there has been a significant theoretical advancement in this field to explain spin polarization of hadrons emitted in these processes. Although current models have successfully explained some of the experimental data based on the coupling between spin polarization and vorticity of the medium, they still lack a clear understanding of the differential measurements. This is commonly interpreted as an indication that the spin needs to be treated as an independent degree of freedom whose dynamics is not entirely bound to flow circulation. In particular, if the spin is a macroscopic property of the system, in equilibrium its dynamics should follow hydrodynamic laws. Here, we develop a framework of relativistic hydrodynamics which includes spin degrees of freedom from the quantum kinetic theory for Dirac fermions and use it for modeling the dynamics of matter. Following experimental observations, we assume that the polarization effects are small and derive conservation laws for the net baryon current, the energy–momentum tensor and the spin tensor based on the de Groot–van Leeuwen–van Weert definitions of these currents. We present various properties of the spin polarization tensor and its components, analyze the propagation properties of the spin polarization components, and derive the spin-wave velocity for arbitrary statistics. We find that only the transverse spin components propagate, analogously to the electromagnetic waves. Finally, using our framework, we study the space–time evolution of the spin polarization for the systems respecting certain space–time symmetries and calculate the mean spin polarization per particle, which can be compared to the experimental data. We find that, for some observables, our spin polarization results agree qualitatively with the experimental findings and other model calculations.

In this paper, we use an Effective Field Theory (EFT) approach to evaluate the viability of the Higgs to account for the $g-2$ anomaly. Although the SM contribution of the Higgs to the muon’s magnetic dipole moment is negligible, using a bottom-up EFT, we show that given the current level of experimental limits on the Higgs sector, the Higgs can still yield a viable solution to the $g-2$ anomaly if its couplings to the rest of the SM particles are allowed to deviate from their SM predictions. Such a solution would only require an $O(1)$ fine-tuning. Further, applying unitarity arguments, we show that such a solution would indicate a scale of New Physics (NP) of $\sim$5–8TeV, which could be lowered to $\sim$3.4–4 TeV if the Higgs couplings to the $W$ and $Z$ are assumed to conform to their SM predictions. We show that such a scenario could yield significant enhancement to the di-Higgs production in muon colliders, thus providing further motivation for its consideration. A key takeaway of this study is to highlight the importance of measuring the $\bar{\mu }\mu hh$ coupling in future experiments.

We perform the Faddeev–Jackiw (FJ) canonical quantization for the Podolsky electrodynamics. To this end, we use an extension of the usual FJ formalism for constrained systems with Grassmann dynamical field variables, proposed by us some time ago. Besides, we compare the obtained results with those corresponding to the implementation of the Dirac formalism to this issue. In this way, we see that the extended FJ and the Dirac formalisms provide the same constraints and generalized brackets, thus suggesting the equivalence between these formalisms, at least for the present case. Furthermore, we find that the extended FJ formalism is more economical than the Dirac one as regards the calculation of both the constraints and the generalized brackets. On the other hand, we also compare the mentioned obtained results with the ones corresponding to the analysis of the issue in study by means of the usual FJ formalism, showing that between the extended and the usual FJ formalisms there are significant differences.

In this paper, we introduce the black hole solution in Rastall theory of gravity in the presence of quintessence and the cloud of strings. Our investigations show that this model meets only second-order phase transition in four dimensions. While both the first- and second-order phase transitions are seen in five dimensions. Therefore, according to the AdS/CFT duality, the confinement–deconfinement phase transition only occurs in five dimensions for this model.

It is shown that the following experimentally viable expressions for quark mixing angles ${\theta }_{12}$, ${\theta }_{23}$, ${\theta }_{13}$ and CP-violating phase $\delta$: $sin{\theta }_{12}=\sqrt{m_d/|m_s|}$, $sin{\theta }_{23}=2|m_s|/m_b$, $sin{\theta }_{13}\approx 2m_d/m_b$, $tan\delta =m_b^2{m}_c/6m_t{m}_s^2$ may be derived as stable points of certain fourth power in $V_{\mathrm{\text{CKM}}}$ flavor-invariant potentials built with traces of 3 $\times$ 3 quark up and down mass matrices and the Jarlskog invariant. There is no fine-tuning, potentials’ dimensionless constants are the integer numbers not above 10.

In this paper, we review the construction of the adiabatic expansion for Bose and Fermi systems and show how it may be used to explore the chiral and parity anomalies for Dirac fermions without the need to compute Feynman diagrams. One interesting application examines how the simple spectral-flow picture of the chiral anomaly is modified by the inclusion of a fermion mass.

In this paper, we study the phase transition of the two Higgs-doublets model (2HDM) and consider a scenario of a electroweak phase transition at alignment limit. Using the Cornwall–Jackiw–Tomboulis formalism at finite temperature, we consider the phase transition of the aligned 2HDM in the two-loop double-bubble contribution. By requirement of Goldstone theorem, the effective potential is corrected and the results show that the system obeys a second-order phase transition. A possible thermal history of the early universe has been treated out: the universe undergoes a smooth crossover in the SM, a second-order phase transition in this model before going to a strong first-order transition in the new physics as in recent 2HDMs and supersymmetry (from the EW symmetric to the broken phase).

In this paper, we investigate the extended uncertainty principle (EUP) effects on the Van der Waals (VdW) black holes whose thermal quantities mimic the VdW liquid. We find that the considered formalism imposes an upper bound on the event horizon radius. Thus, the mass, Hawking temperature, and heat capacity become physically meaningful within a certain range of event horizon radii. At a large event horizon radius, the black hole has a remnant. We observe that for a given set of parameters, the VdW black hole can be completely unstable for all horizon radii, while for another set of parameters, it can be unstable or stable depending on the horizon radius.