LHCb continues to expand its world-leading sample of charmed hadrons collected during LHCโs Run 1 (2010-2012) and Run 2 (2015- present). With this data set, LHCb is discovering many previously unobserved charmed states and making the most precise determinations of the properties of known states. LHCbโs latest work on the spectroscopy of charmed hadrons is presented.
We investigate the X(4260) and X(4360) within the framework of the Faddeev Equations under the fixed center approximation. We find a state of I=1 with masses around 4320 MeV and width about 25 MeV for the case of $\rho-X(3700)$ and 4256 MeV for the case of \barD-D_1(2420) with similar width to that of the $\rho-X(3700)$. Hence these states could be associated with the X(4260) and X(4360).
In this talk I will present our results from a reanalysis of the energy leves obtained in a lattice QCD simulation from where the existence of bound states of $KD$ and $KD^*$ are induced and identified with the states $D^*_{s0}(2317)$ and $D^*_{s1}(2460)$. The study is done using effective field theories in a finite volume.
In the last decade, charmed and bottom meson spectroscopy have seen great success in experimental sector. Experiments like LHCb, Babar etc are providing many new states which are being added to their spectroscopy. Newly predicted states like B(5970), D_2(3000),D*(3000), B(5840) and many more still need to assign their proper place in the spectroscopy. So we explored these newly observed...
I will present our recent work of [Eur Phys J C76 (2016) 121]. We study the B weak decay based on the chiral unitary approach that generates the X(3720) resonance, and make predictions for the DDbar invariant mass distribution. From the shape of the distribution, the existence of the resonance below threshold could be induced. We also predict the rate of production of the X(3720)...
The unambiguous identification and systematic study of bound states beyond the constituent quark degrees of freedom, e.g., multiquark states or states with gluonic degrees of freedom (hybrids, glueballs) would provide validation of and valuable input to the quantitative understanding of QCD. Hadron spectroscopy is one of the most important physics goals of BESIII. Since 2009, BESIII has...
The resonant substructure of the four-body decays D0โฯ+ฯโฯ+ฯโ and D0โK+Kโฯ+ฯโ is studied using data collected by the CLEO experiment. An amplitude analysis is performed in order to disentangle the various intermediate state contributions. To limit the model complexity a data driven regularization procedure is applied. The broad resonances a1(1260)+, ฯ(1300)+ and a1(1640)+ are studied in...
We report about recent results obtained at BABAR on three-body decays of charmonium and bottomonium states.
We present Dalitz plot analyses of $J/\psi$ three-body hadronic decays to $\pi^+\pi^-\pi^0$, $K^+K^-\pi^0$ and $K_S K^{\pm}\pi^{\mp}$ ?using the isobar and Veneziano models.The $J/\psi$ is produced through the Inital-State-Radiation process. We also perform Dalitz plot analyses of ...
Using an unitarized effective Lagrangian, we study the deformed line-shape of the $\psi(3770)$, and of other charmonium resonances which were very recently discovered by the BESIII Collaboration. Nearby threshold effects are taken into account.
The precise determination of hadron spectroscopy from fundamental principles pursues to unveil QCD at its non-perturbative regime.
The non-perturbative nature of QCD at hadronic scales implied the development of phenomenological approaches such as quark models or, more recently, computer-based calculations using Lattice QCD.
However, the unique properties of heavy quarkonium systems allow an...
COMPASS is a multi-purpose fixed-target experiment at CERN aimed at studying the structure and spectrum of hadrons. The two-stage spectrometer has a good acceptance over a wide kinematic range and is thus able to measure a wide range of reactions. Light mesons are studied with a negative hadron beam (mostly $\pi^-$) with a momentum of $190~\text{GeV}/c$. The light-meson spectrum is...
The VES experiment has collected high statistics for exclusive reactions with three pion final states:
$ \pi^-\pi^-\pi^+ $ (about $30\cdot10^6$ events) and $\pi^-\pi^0\pi^0 $ (about $16\cdot10^6$ events).
The $ 3\pi $ systems are produced by $\pi^-$ beam ( $ E_{beam} = 28.9 $ GeV ) impinging on the beryllium target.
The dominant production mechanism is the pomeron exchange between...
One of the goals of the COMPASS experiment is the precision study of light meson
spectroscopy, with data for various final states collected in two years of data
taking. With $46\cdot10^6$ exclusive events, the process
$\pi^-p\to\pi^-\pi^+\pi^-p$ constitutes the flagship of these channels.
Based on this data set, an extensive Partial Wave Analysis, using a total of 88
partial waves in the...
We present results on the extraction of tensor resonances in the $\eta\pi$ system in a joint analysis between the JPAC and COMPASS collaborations. We use $S$-matrix principles unitarity and analyticity to constrain the reaction model. We find two $J^{PC}=2^{++}$ resonance poles, the $a_2$ and $a_2'$. We discuss extensions of the model to coupled channel systems and the $3\pi$ sector.
The properties of two-particle bound states have been investigated within a relativistic quantum-field model based on the analytically confined propagators of the constituents. The spectra of quark-antiquark and two-gluon stable states are defined by master equations similar to the ladder BetheโSalpeter equation. The conventional meson spectrum has been estimated with reasonable accuracy in a...
Using Belle energy scan data we report first evidence for the
$\Upsilon(6S) \to \phi \chi_{bJ}(1P)$ transitions and measure the energy
dependence of the $e^+e^- \to \phi \chi_{bJ}(1P)$ cross sections. We
report also on energy dependence for other final states that consist of
bottomonia and light hadrons. Using Belle data collected at the Y(5S) we
measure the $B_s \to D_s X$ inclusive branching...
We study the $\bar B^0_s \to J/\psi K^+ K^-$, $\bar B^0 \to J/\psi K^+ K^-$, $B^- \to J/\psi K^0 K^-$,
$\bar B^0 \to J/\psi \pi^0 \eta$ and $B^- \to J/\psi \pi^- \eta$ decays and compare their mass distributions with those obtained for the $\bar B^0_s \to J/\psi \pi^+ \pi^-$ and $\bar B^0 \to J/\psi \pi^+ \pi^-$. The approach followed consist in a factorization of the weak part and the...
The bottom partners of the $D_{s0}(2317)$ and $D_{s1}(2460)$ have not been measured yet but the existence of these bottom-strange $J^P=0^+$ and $1^+$ states is motivated by heavy quark flavor symmetry (HQFS) and heavy quark spin symmetry (HQSS).
In this talk we will present the predictions for such heavy quark partners using a unitarized effective approach involving $SU(3)$ chiral heavy meson...
The study of hadronic transitions among bottomonium states, and their
relative magnitude, can be used as a bench test for non-perturbative
approaches to QCD. In particular, transitions through an eta meson,
despite involving a heavy quark spin symmetry violation, have been
measured to have an unexpectedly enhanced branching fraction with respect
to those through a dipion system. A set of...
The phenomenological structure of inclusive cross-sections of the production of two neutral $K$ mesons in hadron--hadron, hadron--nucleus and nucleus--nucleus collisions is theoretically investigated taking into account the strangeness conservation in strong and electromagnetic
interactions. Relations describing the dependence
of the correlations of two short-lived and two long-lived neutral...
There have recently been several high-statistics new measurements of the isospin violating decay $\eta \to 3\pi$. Besides the interest in its analysis, these and other data on three-body decays of mesons have originated a revival on the study and the application of the Khuri-Treiman equations. This is a dispersive formalism which allows to simultaneously incorporate the two-body elastic...
We present a determination of the mass, width and coupling of the strange resonances appearing in pion-kaon scattering, the much debated K_0(800), the scalar K_0(1430), the K_1(892) and k_1(1410) vectors, the spin-two K_2(1430) as well as the spin-three K_3(1780). The parameters of each resonance will be determined using a direct analytical continuation of the pion-kaon partial waves by...
Isobar models, successful as they are in providing fits for heavy meson decays,
rely on both parameters which are not physically transparent and sums
of Breit-Wigner functions.
As an alternative, we propose a Multi-Meson-Model (Triple-M) for the
$D^+ \to K^+ K^- K^+$ amplitude.
The decay is assumed to be dominated by the process
$D^+\to W^+ \to K^+ K^- K^+$ and, therefore,
driven by...
The axial anomaly is responsible for the masses and mixing of the mesons $\eta $ and $\eta' $ (especially the latter). An open question is if it affects also other sectors of hadronic phenomenology. We show that anomalous terms can be important to understand the spectroscopy of pseudotensor mesons $\eta_2 (1645) $ and $\eta_2 (1870) $ (which can be investigated in the GlueX experiment at...
We have recently extended the scalar-pseudoscalar sector of a generalized NJL Lagrangian that includes all NLO non derivative interactions in Nc counting (including explicit symmetry breaking ones) in order to incorporate the spin 1 mesons in the low-lying ground state of QCD [1]. Upon bosonization, the well known mixing of the scalar-vector and of the pseudoscalar- axial-vector fields...
Hybrid mesons consist of a quark-antiquark pair bound together by a gluonic field that is in an excited state. A rich spectrum of hybrid meson states has been predicted, but only a few experiments have reported evidence of their existence. Measuring the spectrum of these states will provide valuable information on the gluonic degrees of freedom of QCD in the quark-confinement regime.
The...
The COMPASS experiment at CERN uses a high-energy pion beam scattered off protons and heavier nuclei to produce mesonic excitations, which are observed in multi-particle final states subjected to partial-wave analyses. In addition to studying the properties of established mesons with unprecedented accuracy, the large existing data samples allow us to detect possibly exotic states. These either...
A truncated solution of a gauge invariant subset of the Schwinger-Dyson (SD) equations for QCD leads to a functional form of the strong running coupling showing a freezing in the infrared, which is best understood as a dynamical generation of a gluon mass function, giving rise to a momentum dependence which is free from infrared divergences. The generation of such a mass is associated with the...
The Green's functions of QCD encode the properties of hadrons, with the appearance of (colour singlet) poles in n-point functions corresponding to bound-states and resonances. There are several techniques by which such information may be extracted, including lattice QCD and functional methods. We discuss recent progress in applying nPI effective action techniques to the systematic truncation...
Photoproduction of meson pairs off nucleons has gained a lot of interest mainly because it allows to study sequential decays of nucleon resonances via some intermediate excited states. This may give access to states that have only tiny decay branching ratios for direct decays to the nucleon ground state by emission of a single meson. In particular, pion pairs and pi-eta pairs have been studied...
