Search results for "38"
showing 10 items of 1730 documents
An improved limit for Γee of X(3872) and Γee measurement of ψ(3686)
2015
Using the data sets taken at center-of-mass energies above 4 GeV by the BESIII detector at the BEPCII storage ring, we search for the reaction e(+)e(-) -> gamma(ISR) X(3872) -> gamma(ISR)pi(+ ...
Observation of a Charged Charmoniumlike Structure ine+e−→π+π−J/ψats=4.26 GeV
2013
We study the process e(+)e(-) -> pi(+)pi(-) J/psi at a center-of-mass energy of 4.260 GeV using a 525 pb(-1) data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9 +/- 1.9 +/- 3.7) pb, consistent with the production of the Y(4260). We observe a structure at around 3.9 GeV/c(2) in the pi(+/-) J/psi mass spectrum, which we refer to as the Z(c)(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the pi(+/-) J/psi invariant mass spectrum, neglecting interference, results in a mass of (3899.0 +/- 3.6 +/- 4.9) MeV/c(2) and a width…
Search for prompt production ofχcandX(3872)ine+e−annihilations
2007
We have searched for prompt production of χc1, χc2 and X(3872) in continuum e+e- annihilations using a 386fb-1 data sample collected around s=10.6GeV with the BABAR detector using the γJ/ψ decay mode. After accounting for the feed-down from ψ(2S)→γχc1,2, no significant signal for prompt χc1,2 production is observed. We present improved upper limits at 90% confidence level on the production cross sections of 77fb for χc1 and 79fb for χc2, for events where the χc momentum exceeds 2.0 GeV and there are at least three additional charged tracks. These limits are consistent with NRQCD predictions. We also set an upper limit on the prompt production of X(3872) through the decay X(3872)→γJ/ψ. © 200…
Heavy Quark Symmetries: Molecular partners of theX(3872) andZb(10610)/Zb′(10650)
2014
In this work, we have made use of the identification of the X (3872) and Z b (10610)/Z b ′(10650) as heavy meson-heavy antimeson molecules to establish some consequences derived from the symmetries that these heavy meson-heavy antimeson systems must have. We show the most general effective lagrangian that respects these symmetries only depends on four undetermined low energy constants (LECs), which will be fitted to reproduce the experimental data about the resonances we are identifying as molecular states. Then, we obtain a whole new set of states in the spectrum that could also be thought as heavy meson-heavy antimeson molecules. Finally, using another different symmetry: Heavy Antiquark-…
One-photon decay of the tetraquark stateX(3872)→γ+J/ψin a relativistic constituent quark model with infrared confinement
2011
We further explore the consequences of treating the $X(3872)$ meson as a tetraquark bound state by analyzing its one-photon decay $X\ensuremath{\rightarrow}\ensuremath{\gamma}+J/\ensuremath{\psi}$ in the framework of our approach developed in previous papers which incorporates quark confinement in an effective way. To introduce electromagnetism we gauge a nonlocal effective Lagrangian describing the interaction of the $X(3872)$ meson with its four constituent quarks by using the $P$-exponential path-independent formalism. We calculate the matrix element of the transition $X\ensuremath{\rightarrow}\ensuremath{\gamma}+J/\ensuremath{\psi}$ and prove its gauge invariance. We evaluate the $X\ens…
X(3872) and its charmonium content in Heavy Quark limit
2016
X (3872) still presents many puzzles more than a decade after its discovery. Some of its properties, like the isospin violating decays, can easily be accommodated in a molecular model, whereas its other properties, such as radiative decays can be more naturally explained in the quarkonium picture. The best of these schemes can be combined in a picture of X (3872) where it is dominantly a molecular state with some charmonium components. In this work, we present a model based on heavy quark symmetry which describes X (3872) as a superposition of molecular and charmonium components.
Charmonium spectroscopy above thresholds
2009
We present a systematic and self-consistent analysis of four-quark charmonium states and applied it to study compact four-quark systems and meson-meson molecules. Our results are robust and should serve to clarify the situation of charmonium spectroscopy above the threshold production of charmed mesons.
Decay widths of the spin-2 partners of the X (3872)
2015
We consider the $X(3872)$ resonance as a $J^{PC}=1^{++}$ $D\bar D^*$ hadronic molecule. According to heavy quark spin symmetry, there will exist a partner with quantum numbers $2^{++}$, $X_{2}$, which would be a $D^*\bar D^*$ loosely bound state. The $X_{2}$ is expected to decay dominantly into $D\bar D$, $D\bar D^*$ and $\bar D D^*$ in $d$-wave. In this work, we calculate the decay widths of the $X_{2}$ resonance into the above channels, as well as those of its bottom partner, $X_{b2}$, the mass of which comes from assuming heavy flavor symmetry for the contact terms. We find partial widths of the $X_{2}$ and $X_{b2}$ of the order of a few MeV. Finally, we also study the radiative $X_2\to …
Triangle singularity in the B−→K−π0X(3872) reaction and sensitivity to the X(3872) mass
2020
We have done a study of the ${B}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}X(3872)$ reaction by means of a triangle mechanism via the chain of reactions: ${B}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{D}^{*0}{\overline{D}}^{*0}$; ${D}^{*0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{D}^{0}$; ${D}^{0}{\overline{D}}^{*0}\ensuremath{\rightarrow}X(3872)$. We show that this mechanism generates a triangle singularity in the ${\ensuremath{\pi}}^{0}X(3872)$ invariant mass for a very narrow window of the $X(3872)$ mass, around the present measured values, and show that the peak positions and the shape of the mass distributions are sensitiv…
Timing of the Accreting Millisecond Pulsar XTE J1814-338
2006
We present a precise timing analysis of the accreting millisecond pulsar XTE J1814-338 during its 2003 outburst, observed by RXTE. A full orbital solution is given for the first time; Doppler effects induced by the motion of the source in the binary system were corrected, leading to a refined estimate of the orbital period, P_orb=15388.7229(2)s, and of the projected semimajor axis, a sini/c= 390.633(9) lt-ms. We could then investigate the spin behaviour of the accreting compact object during the outburst. We report here a refined value of the spin frequency (nu=314.35610879(1) Hz) and the first estimate of the spin frequency derivative of this source while accreting (nu^dot=(-6.7 +/- 0.7) 1…