Related papers: Pionic transitions from X(3872) to chi_{cJ}
In order to understand the structure of the X(3872), the $c \bar c$ charmonium core state coupling to the $D^0 \bar D^{\ast 0}$ and $D^+ D^{\ast -}$ molecular states are studied. The strengths of the couplings between the charmonium state…
We investigate E1 radiative transitions within charmonium in a relativistic approach based on light-front QCD. In quantum field theory, two sets of processes are pure E1: $\chi_{c0} \to J/\psi \gamma$ ($\psi\to \chi_{c0}\gamma$) and $h_c…
We study one-pion transitions between charm baryon states in the framework of a relativistic three-quark model. We calculate the charm baryon-pion coupling factors that govern the S-wave, P-wave and D-wave one-pion transitions from the…
We examine possible J^PC quantum number assignments for the X(3872). Angular correlations between final state particles in X(3872) --> pi+pi- J/psi decays are used to rule out J^PC values of 0++ and 0-+. The shape of the pi+pi- mass…
The very recent analysis by BaBar Collaboration indicates that the $X(3872)$ may favor the quantum number $J^{PC}=2^{-+}$ rather than the previously assumed $1^{++}$. By pretending the $\eta_{c2}(1D)$ charmonium to be the $X(3872)$, we…
We present that including the hadron loop effects could help us to understand the spectrum of the heavier charmonium-like states and their decays simultaneously. The observed states could be represented by the poles on the complex energy…
Despite being extensively studied since their initial discovery in 2003, the XYZ states do not yet have a clear interpretation. BESIII recently collected additional data above 4 GeV which can be used to further study these exotic hadron…
The effects of intermediate charmed mesons on charmonium transitions with the emission of one pion or eta are studied systematically. Based on a non-relativistic effective field theory we show that charmed meson loops are enhanced compared…
It is pointed out that dipion invariant mass spectrum in $X (3872) \to \pi \pi J/\psi$ is a useful probe for the $J^{PC}$ quantum number of the X(3872), complementary to the angular distributions. If X(3872) is a $^1 P_1$ state, the dipion…
An interesting controversy has emerged challenging the widely accepted nature of the $X(3915)$ and the $X(3930)$ resonances, which had initially been assigned to the $\chi_{c0}(2P)$ and $\chi_{c2}(2P)$ $c\bar c$ states, respectively. To…
The recently observed X(3872) resonance, which is difficult to be assigned a conventional $c\bar{c}$ charmonium state in the quark model, may be interpreted as a molecular state. Such a molecular state is a hidden flavor four quark state…
We calculate the density shift and broadening of selected dipole transition lines of pionic helium in gaseous helium at low temperatures up to T=12 K and pressure up to a few bar. In the approximation of binary collisions the shift and…
If the $X(3872)$ is described by the picture as a mixture of the charmonium and molecular $D^{\ast} D$ states; $Y(3940)$ as a mixture of the $\chi_{c0}$ and $D^\ast D^\ast$ states; and $X(4260)$ as a mixture of the tetra-quark and…
The Beijing Spectrometer (BESIII) Collaboration reconstructed the invariant mass of three pairs of positive and negative pions by studying the decay process of charmonium to a photon and three pairs of positive and negative pions. They…
The X(3872) radiative decay is discussed by employing a two-meson multichannel model with the charmonium components, which explains many of the other observed features of X(3872). We have found that the ratio of the branching fractions of…
Three more $X$ particles are established in the 2014 Particle Data compared with the 2012 ones. There are now five established $X$ particles named as $X(3872)$, $X(3900)$, $X(4260)$, $X(4360)$, and $X(4660)$. Since the first $X$ particle…
After commenting on the state of contemporary hadronic physics and spectroscopy, I highlight four areas where the action is: searching for the relevant degrees of freedom, mesons with beauty and charm, chiral symmetry and the D_{sJ} levels,…
The mass shift of charmonium states in nuclear matter is studied in the perturbative QCD approach. The leading-order effect due to the change of gluon condensate in nuclear matter is evaluated using the leading-order QCD formula, while the…
Properties of the charmonium-like state X(3872) are investigated and its nature is discussed as based on the existing experimental data. In particular, we analyse the new data from Belle and BaBar Collaborations and argue that, while the…
An overview is given on recent progress in the study of quarkonium spectroscopy at the B-factories. In particular, an updated status report is presented of the long list of "charmonium-like" resonances newly discovered, whose assignment as…