High Energy Physics - Phenomenology (hep-ph)

Abstract: I review the status of lattice QCD calculations of the hadronic contributions to the muon's anomalous magnetic moment, focussing on the hadronic vacuum polarisation contribution which dominates the uncertainty of the Standard Model prediction.This quantity exhibits a tension between recent lattice QCD results and the traditional data-driven dispersive method. I discuss the implications for the running of the electromagnetic coupling and the consistency of global fits using electroweak precision data.

Abstract: In the presence of a momentum cutoff, effective theories seem unable to faithfully reproduce the so called chiral anomaly in the Standard Model. A novel prospect to overcome this related issue is discussed herein via the calculation of the $\gamma^{*}\pi^0\gamma$ transition form factor, $G^{\gamma^* \pi^0 \gamma}(Q^2)$, whose normalization is intimately connected with the chiral anomaly and dynamical chiral symmetry breaking (DCSB). To compute such transition, we employ contact interaction model of Quantum Chromodynamics (QCD) under a modified rainbow ladder truncation, which automatically generates a quark anomalous magnetic moment term, weighted by a strenght parameter $\xi$. This term, whose origin is also connected with DCSB, is interpreted as an additional interaction that mimics the complex dynamics beyond the cutoff. By fixing $\xi$ to produce the value of $G^{\gamma^* \pi^0 \gamma}(0)$ dictated by the chiral anomaly, the computed transition form factor, as well as the interaction radius and neutral pion decay width, turn out to be comparable with QCD-based studies and experimental data.

Abstract: We study the dissociation effect of $J/\Psi$ in magnetized, rotating QGP matter at finite temperature and chemical potential using gauge/gravity duality. By incorporating angular velocity into the holographic magnetic catalysis model, we analyze the influence of temperature, chemical potential, magnetic field, and angular velocity on the properties of $J/\Psi$ meson. The results reveal that temperature, chemical potential, and rotation enhance the dissociation effect and increase the effective mass in the QGP phase. However, the magnetic field suppresses dissociation, and its effect on the effective mass is non-trivial. Additionally, we explore the interplay between magnetic field and rotation, identifying a critical angular velocity that determines the dominant effect. As a parallel study, we also examine the rotation effect in the holographic inverse magnetic catalysis model, although the magnetic field exhibits distinctly different behaviors in these two models, the impact of rotation on the dissociation effect of $J/\Psi$ is similar. Finally, we investigate the influence of electric field and demonstrate that it also speeds up the $J/\Psi$ dissociation.

Abstract: Tackling the many open questions in particle physics will require the construction of new colliders. This short note includes a few considerations that seem to be brought up rarely.

Abstract: Based on the assumption that the $a_0(1700/1800)$ meson is a state similar to the four-quark state from the MIT bag, belonging to either the $\underline{9}^*$ or the $\underline{36}^*$ $q^2\bar q^2$ multiplet, we analyze the influence of the strong $a_0(1700/1800)$ coupling to the vector channels $K^*\bar K^*$, $\rho\phi$, and $\rho \omega$ on its line shape in the decay channels into pseudoscalar mesons $K\bar K$, $\pi\eta$, and $\pi\eta'$. This effect depends on the location of the resonance mass $m_{a_0}$ relative to the nominal thresholds of vector channels. For example, if $m_{a_0}\approx 1700$ MeV, then the influence turns out to be hidden in a fairly wide range of coupling constants. In any case, to confirm the presence of the strong $a_0(1700/1800)$ coupling to vector channels, the direct detection of the decays $a_0(1700/1800)\to K^*\bar K^*$, $\rho\phi$, $\rho\omega$ is required. The appearance of even certain hints of the existence of these decays would make it possible to fundamentally advance in understanding the nature of the new $a_0$ state.

Abstract: We present resummed predictions for Higgs boson rapidity distribution through bottom quark annihilation at next-to-next-to-leading logarithmic (NNLL) accuracy matched to next-to-next-to-leading order (NNLO) in the strong coupling. Exploiting the universal behavior of soft radiation near the threshold, we determine the analytic expressions for the process-dependent and universal perturbative ingredients for threshold resummation in double singular limits of partonic threshold variables $z_1,z_2$. Subsequently, the threshold resummation is performed in the double Mellin space within the standard QCD framework. We also determine the third-order process-dependent non-logarithmic coefficients using three-loop bottom quark form factor and third-order quark soft distribution function in rapidity distribution. Further, we have studied the effects of these new third-order ingredients on the rapidity distribution of Higgs boson for 13 TeV LHC. We observe a better perturbative convergence in the resummed predictions on the Higgs rapidity spectrum in bottom quark annihilation. We also find that the NNLL and N3LL corrections are sizeable which typically are of the order of $-2.5\%$ and $-1.5\%$ over the respective available fixed orders with the scale uncertainty remaining at the same level as the fixed order.

Abstract: In this work, we investigate the spectroscopic properties of $1F$-wave charmed baryons, which have not yet been observed in experiments. We employ a non-relativistic potential model and utilize the Gaussian expansion method to obtain the mass spectra of these charmed baryons. Additionally, we focus on the two-body Okubo-Zweig-Iizuka allowed strong decay behaviors, which plays a crucial role in characterizing the properties of these baryons. Our comprehensive analyses of the mass spectra and two-body Okubo-Zweig-Iizuka allowed decay behaviors provides valuable insights for future experimental investigations. This study significantly contributes to our understandings of the spectroscopic properties of $1F$-wave charmed baryons.