We study the thermal properties of quantum field theories (QFT) with three-leg interaction vertices $gφ^{3}$ and $gSφ^{2}$ ($φ$ and $S$ being scalar fields), which constitute the relativistic counterpart of the Yukawa potential. We follow a non-perturbative unitarized one-loop resummed technique for which the theory is unitary and well-defined for a large range of values of the coupling constant $g$. Using the partial wave decomposition of two-body scattering we calculate the phase shifts, whose derivatives are used to infer the pressure of the system at nonzero temperature by using the so-called phase shift formalism. A $φφ$ bound state is formed when the coupling $g$ is larger than a certain critical value. As the main outcomes of this work, we estimate the influence of particle interaction on the pressure (both without and with the bound state), and we demonstrate that the latter is always continuous as a function of the coupling constant $g$ (no sudden jumps occurs when the bound state forms), and we show that the contribution of the bound state to the pressure does not count as \textit{one} state in the thermal gas, since a cancellation with the residual $φφ$ interaction occurs. The amount of this cancellation depends on the details of the model and its parameters and a variety of possible scenarios is presented. %Moreover, even when no bound state occurs, we estimate the role of the interaction (including a resonance in the $gSφ^{2}$ theory), which is in general non-negligible. We also show how the overall effect of the interaction, including eventual resonances and bound states, can be formally described by a unique expression that makes use of the phase shift continued below the threshold.
QCD matter at a finite magnetic field and nonzero chemical potential
School of Physics and Information Technology, Shaanxi Normal University（陕西师范大学物理与信息技术学院）；School of Physics Science and Engineering, Tongji University（同济大学物理科学与工程学院）；School of Science, Xi’an Jiaotong University（西安交通大学理学院）
Probing a new strongly interacting sector via composite diboson resonances
Diphoton resonance was a crucial discovery mode for the 125 GeV SM Higgs boson at the LHC. This mode or the more general diboson modes may also play an important role in probing for new physics beyond the SM. In this paper, we consider the possibility that a diphoton resonance is due to a composite (pseudo)scalar boson, whose constituents are either new hyperquarks Q or scalar hyperquarks tilde{Q} confined by a new hypercolor force at a confinement scale Lambda_h. Assuming the mass m_Q (or m_{tilde Q} ) >> Lambda_h, a diphoton resonance could be interpreted as either a Q bar{Q} state eta_Q wit…
Widen the Resonance at Ultra-High Energies: Novel Probes of Neutrino Self-interactions in the High-Mass Regime
Fermi National Accelerator Laboratory（费米国家加速器实验室）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）
