The rigorous quantum mechanical definition of a resonance requires determining the pole position in the second Riemann sheet of the analytically continued partial wave scattering amplitude in the complex Mandelstam s-variable plane. For meson resonances we investigate the alternative Breit-Wigner (BW) definition within the large Nc expansion. By assuming that the pole position is ${\cal O} (N_C^{0})$ and exploiting unitarity, we show that the BW determination of the resonance mass differs from the pole position by ${\cal O} (N_C^{-2})$ terms, which can be extracted from pi-pi scattering data. For the case of the f0(600) pole, the BW scalar mass is predicted to occur at about 700 MeV while the true value is located at about 800 MeV.
Dark matter (DM) annihilation in the galactic halo can be enhanced relative to that in the early Universe due to the Breit-Wigner enhancement, if the DM particles annihilate through a narrow resonance. Although the $s$-wave Breit-Wigner enhancement can provide a consistent explanation for both the observed cosmic-ray (CR) positron excess and the DM thermal relic density, it is severely constrained by the observations of gamma rays from dwarf spheroidal satellite galaxies (dSphs) and the cosmic microwave background (CMB), which have relatively lower allowed DM annihilation cross section and typ…
Rekindling s-Wave Dark Matter Annihilation Below 10GeV with Breit-Wigner Effects
Laboratoire d’Annecy de Physique Théorique, CNRS – USMB（理论物理安纳西实验室，法国国家科学研究中心-萨瓦大学）；Institute for Particle Physics Phenomenology, Department of Physics Durham University（达勒姆大学粒子物理现象学研究所）
We have developed a covariant isobar model to phenomenologically explain the four possible isospin channels of $KΣ$ photoproduction. To obtain a consistent reaction amplitude, which is free from the lower-spin background problem, we used the consistent electromagnetic and hadronic interactions described in our previous report. We used all available experimental data, including the recent MAMI A2 2018 data obtained for the $K^0Σ^+$ and $K^0Σ^0$ isospin channels. By fitting the calculated observables to these data we extract the resonance properties, including their Breit-Wigner and pole paramet…
The broad non-strange meson $f_0$(500) is considered to be a non-Breit-Wigner resonance. It is generally assumed that if a resonance is broad it can hardly be described by a Breit-Wigner form. We show here that is not true neither for the broad Z boson, nor for the much narrower $Δ(1232)$, and explain why the $f_0$(500) fits with them perfectly. Key differences between them boil down to a single parameter: the angle at which we see the resonance pole from the threshold, which explains the background, the residue phase, and the difference between the pole and Breit-Wigner parameters.
We analyze the quasi-two-body charmed $B$ decays $B^{+,0}_{(s)} \to D_{(s)}^* P_2 \to D_{(s)} P_1 P_2$ with $P_{1,2}$ as a pion or kaon. The intermediate processes $B_{(s)} \to D_{(s)}^* P_2 $ are calculated with the factorization-assisted topological-amplitude approach and the resonant effects are calculated with the Breit-Wigner formalism. Taking all p-wave resonance states $ \bar D_{(s)}^*$ into consideration, we present the related branching fractions, calculate the Breit-Wigner-Tail effects, and investigate the flavor $SU(3)$ breaking effects. Most of our branching fractions are consisten…
First, we discuss the conditions under which the non-relativistic and relativistic types of the Breit-Wigner energy distributions are obtained. Then, upon insisting on the correct normalization of the energy distribution, we introduce a Flatté-like relativistic distribution -- denominated as Sill distribution -- that (i) contains left-threshold effects, (ii) is properly normalized for any decay width, (iii) can be obtained as an appropriate limit in which the decay width is a constant, (iv) is easily generalized to the multi-channel case (v) as well as to a convoluted form in case of a decay c…
Comment on "Mass and K Lambda coupling of N*(1535)"
文[1]指出，当考虑到与K λ通道的强耦合时，核子N（1535）最轻轨道激发的Breit-Wigner质量向低值移动。新的数值比最轻的径向激发态N（1440）的质量要小，这有效地解决了传统组分夸克模型长期存在的问题。在这篇评论中，我们指出，减少的不是N（1535）的布莱特-维格纳质量，而是它的裸质量。[1]B. C. Liu和B. S. Zou，Phys. Rev. Lett. 96，042002（2006）。
The cross sections of $e^+e^- \rightarrow πZ_c(3900) \rightarrow ππJ/ψ$ and $e^+e^- \rightarrow πZ_c(3900) \rightarrow πD\bar{D}^{*}$ have been measured by BESIII experiment. We try to perform a combined fit to the cross sections with one Breit-Wigner function, the fit results show the structure's mass and width are $M=(4232\pm5)$ MeV/$c^2$, $Γ=(65\pm21)$ MeV. The ratio $\frac{\mathcal{B}(Z_c(3900)\rightarrow D\bar{D}^{*})}{\mathcal{B}(Z_c(3900)\rightarrowπJ/ψ)}$ is determined to be $(16\pm6)$. We also try to fit the cross sections with two Breit-Wigner functions, while we can't come to any de…
We study the dynamics of self-interacting scalar fields with $Z_2$ symmetry governed by a relativistic Israel-Stuart type diffusion equation in the vicinity of a critical point. We calculate spectral functions of the order parameter in mean-field approximation as well as using first-principles classical-statistical lattice simulations in real-time. We observe that the spectral functions are well-described by single Breit-Wigner shapes. Away from criticality, the dispersion matches the expectations from the mean-field approach. At the critical point, the spectral functions largely keep their Br…
Study of localized $CP$ violation in $B^-\rightarrow π^- π^+π^-$ and the branching ratio of $B^-\rightarrow σ(600)π^-$ in the QCD factorization approach
