Related papers: Can the X(1750) be a $\Phi$(1750)?
We study the effects of new-physics contributions to B --> pi pi decays, which can be parametrized as four new complex quantities. A simple analysis is provided by utilizing the reparametrization invariance of the decay amplitudes. We find…
We have searched for a bound state of kaon and pion denoted by $X$. The $X$ was conjectured to explain the so-called $\Theta^+$ resonance as a bound state of kaon, pion and nucleon. This model explains almost all properties of the…
We study pi eta scattering in a model which starts from the tree diagrams of a non-linear chiral Lagrangian including appropriate resonances. Previously, models of this type were applied to pi pi and pi K scattering and were seen to require…
We study the decay $J/\psi\to\pi^{+}\pi^{-}\pi^{0}$ within the framework of the Khuri-Treiman equations. We find that the BESIII experimental di-pion mass distribution in the $\rho(770)$-region is well reproduced with a once-subtracted…
Given a family of complex affine planes, we show that it is trivial over a Zariski open subset of the base. The proof relies upon a relative version of the contraction theorem.
We present a new model independent amplitude analysis of reaction pi(-)p->pi(-) pi(+)n measured at CERN at 17.2 GeV/c on polarized target using a Monte Carlo method for dipion mass 580-1080 MeV. The two solutions for measured moduli…
The final state of the decay D0 --> pi+ pi- pi0 is analyzed in terms of isospin eigenstates. It is shown that the final state is dominated by the isospin-0 component. This suggests that isospin considerations may provide insight into this…
Let $U$ be a smooth $\mathbb C$-scheme, $f:U\to\mathbb A^1$ a regular function, and $X=$Crit$(f)$ the critical locus, as a $\mathbb C$-subscheme of $U$. Then one can define the "perverse sheaf of vanishing cycles" $PV_{U,f}$, a perverse…
The dependence of the nucleon polarization in the reaction $e^+ + e^- \to N + \bar{N} +\pi^0 $ over different invariant variables in frame of the non-resonant mechanism, has been derived. The nucleon polarization is expressed in terms of…
K-matrix analysis of the $00^{++}$ wave is performed in the channels $\pi\pi,~K\bar K,~\eta\eta$ and $4\pi$ in the mass region up to 1550 MeV. The fit is based on the following data: $p\bar p ~(at~rest)\to \pi^0\pi^0\pi^0$,…
We use chiral perturbation theory to evaluate the scattering amplitude for the process Pi^+ K^- to Pi^+ K^- at leading and next-to-leading orders in the chiral counting and in the presence of isospin breaking effects. We also discuss the…
Using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.178 to 4.600 GeV, we study the process $e^+e^-\rightarrow\pi^{0}X(3872)\gamma$ and search for…
We discuss the existence of the light scalar meson K^*_0(800) (also called kappa) in a rigorous way, by showing the presence of a pole in the pi K --> pi K amplitude on the second Riemann sheet. For this purpose, we study the domain of…
We present an analysis of the process $e^+e^-\to V^*\to\pi\pi\gamma$, where $V=\gamma$ or $V=Z$ boson, in the kinematical region where $\sqrt{s}$, the c.m. energy of the $e^+e^-$ pair, is large but much below the $Z$-pole. The subprocess…
We present a study of the reaction e+e- \to pi+pi-gamma at the phi peak with the KLOE detector at the phi-factory DAPHNE. This reaction allows us to obtain the cross section for \e+e- \to pi+pi- from the e+e- center-of-mass energy W =…
Fano mechanism is the universal explanation of asymmetric resonance appearing in different systems. We report the evidence of Fano-like resonance in selective reflection from a resonant two-level medium. We draw an analogy with the…
The effect of isoscalar S-wave multi-channel pion-pion scattering ($\pi\pi\to\pi\pi,K\bar{K},\eta\eta$) is considered in the analysis of data on decays of the $\Upsilon$-meson family -- $\Upsilon(2S)\to\Upsilon(1S)\pi\pi$,…
We estimate a possible contribution of the two-pion system $f_0(500)$ wide resonance to the decay probability of the super rare decay $K^+ \to 3\pi^0 e^+ \nu$. We vary the width of the resonance from 0.01 MeV to 1000 MeV. We found that the…
The lowest-lying resonance in the QCD spectrum is the $0^{++}$ isoscalar $\sigma$ meson, also known as the $f_0(500)$. We augment SU(2) chiral perturbation theory ($\chi$PT) by including the $\sigma$ meson as an additional explicit degree…
We study the spin-Peierls transition in a Heisenberg spin chain coupled to optical bond-phonons. Quantum Monte Carlo results for systems with up to N=256 spins show unambiguously that the transition occurs only when the spin-phonon coupling…