International Journal of Modern Physics A

Searches for pairs of Higgs bosons are the best tools to precisely measure the Higgs boson self-coupling ${\lambda }_{hhh}$ in future colliders. We study various strategies for the $hh\to b\bar{b}b\bar{b}$ search in the HL-LHC era with focus on constraining ${\lambda }_{hhh}$. We implement a machine-learning-based approach to separate signal and background and apply recent advances in machine learning interpretability, compare the traditional 4 b-jet reconstruction to final states with 1 or 2 large-radius jets, and test scenarios with different top-quark Yukawa couplings, among other factors. This talk was presented as part of the Mini-workshop on Machine Learning at the 10th International Conference on New Frontiers in Physics (ICNFP-2021).

In this paper, we consider a general static, spherically symmetric background in the quadratic beyond Horndeski theory and analyze the behavior of linear perturbations in both parity odd and parity even sectors. We derive a full set of stability conditions for an arbitrary static, spherically symmetric solution which guarantees absence of ghosts, gradient instabilities, tachyons and superluminal modes in both sectors.

General relativity and quantum mechanics are not only fundamentally different theories giving explanations of how nature works but also genuinely incompatible descriptions of reality. The violation of the principles of relativity and equivalence, at quantum scales, belongs to the main conceptual difficulties of reconciling principles of quantum mechanics with general relativity so that their scales of applicability are entirely distinct. When generalized noncommutative Heisenberg algebra accommodating impacts of finite gravitational fields as specified by quantum loop gravity, doubly special relativity, and string theory, for instance, is thoughtfully applied to the eight-dimensional Finsler manifold. In the natural generalization of the pseudo-Riemannian manifold, in which the quadratic restriction on the length measure is relaxed, we have been able to define quantum-induced revisiting fundamental tensor in relativistic regime and thereby extending its applicability to quantum scales. By constructing the affine connections on a four-dimensional pseudo-Riemannian manifold, we have determined the quantum-induced revisiting Riemann curvature tensor and its contractions, the Ricci curvature tensor, and scalar in relativistic regime. Consequently, we have been able to construct the Einstein tensor, in which besides quantization additional geometric structures and curvatures are emerged. As in Einstein’s classical theory of general relativity, we have proved that the covariant derivative of the modified Einstein tensor vanishes, as well. We conclude that the quantum-induced corrections establish quantum properties to the space–time coordinates and momenta. Accordingly, the space–time curvature endows additional curvature and geometrical structure as well as discretization which likely enable sensical predictions of Einstein’s general relativity, at the quantum scale.

This report highlights the recent BESIII results related to the measurement of the R value, radiative decays of $J∕\psi$ and the polarization of $D^0\to \omega \varphi$ decay. BESIII, a symmetric electron-positron collider experiment, has collected a large data sample at several energy points in the tau-charm region, including the $J∕\psi$ and $\psi (3770)$ resonances. Based on the data samples collected at 14 center-of-mass energy ($\sqrt{s}$) points between 2.2323 and 3.671GeV, BESIII has achieved a measurement of the R value with an accuracy down to the level of $2.6\%$ for $\sqrt{s}<3.1$GeV and $3.0\%$ for $\sqrt{s}>3.1$GeV. BESIII has also observed the $X(2600)$ resonance in radiative $J∕\psi$ decay and the polarization of $D^0\to \omega \varphi$ for the first time. The polarization of $D^0\to \omega \varphi$ saturates with completely transverse polarization, which is inconsistent with the existing theoretical models. These results are useful in testing the predictions of the Standard Model.

The data on charge balance function in Pb+Pb collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed with the HYDJET++ model. For central collisions, the width of the charge balance function at low transverse momentum intervals is larger in the model than in data. An approach, which takes into account the event-by-event charge conservation, has been implemented into the thermal part of the model at the stage of hadron production. This approach implies two particle charge correlations with a certain length and allows to reproduce experimental widths.

Ultraperipheral collisions of heavy ions give physicists an opportunity for studies of two-photon-induced processes in a clean environment with strongly suppressed hadronic interactions. In particular, measurements of cross-section of the process can be used to set new constraints on poorly known anomalous magnetic moment of tau lepton. Obtaining a precise experimental value for tau $g-2$ becomes especially important in view of new data from the Muon $g-2$ experiment and also for verification of Standard Model extensions, including supersymmetry and theories with composite leptons. With the ALICE experiment in Run 3 it will be possible to address low transverse momenta for reconstructed charged particles to increase the number of available events. We have carried out realistic simulations of the ALICE detector to develop event selection strategy for tau decay events. In this paper, we discuss the results of the simulations and feasibility of tau $g-2$ measurement with the ALICE experiment.

Using SU(3) lattice quantum chromodynamics (QCD), we study for the first time the effective potential of the Polyakov loop $〈P〉$ at finite temperature, i.e. the thermodynamic potential, in the field-theoretical way. In the framework of the reweighting method in lattice QCD, we express the effective potential $V_{\mathrm{\text{eff}}}(〈P〉)$ using the expectation value without a source term. In particular, we consider the most difficult and interesting case of vacuum coexistence at the critical temperature $T_c$. We adopt SU(3) quenched lattice QCD on $48^3\times 6$ at $\beta =5.89379$, which corresponds exactly to the critical temperature $T_c$ of the deconfinement phase transition, and use 200,000 Monte Carlo configurations. After categorizing the gauge configurations into one $Z_3$-symmetric and three $Z_3$-broken vacua each, we perform a vacuum-associated reweighting method, using the gauge configurations around each vacuum separately. Finally, we obtain the Polyakov-loop effective potential, which is well depicted around the $Z_3$-symmetric and $Z_3$-broken vacua.

We consider a five-dimensional fully anisotropic holographic model supported by Einstein-dilaton-three-Maxwell action. This type of model within different warp-factors and the coupling function for the Maxwell field providing the nontrivial chemical potential can describe magnetic/inverse magnetic catalysis phenomena expected from lattice results for heavy and light quarks. To reproduce magnetic catalysis phenomena for heavy quarks, we should modify the warp factor and consider additional polynomial terms in warp factor. It is expected that the first-order phase transition will coincide with chiral phase transition and the phase between first-order phase transition line and confinement/deconfinement line can be interpreted as quarkyonic phase.