Quark Structure of the X (4500), X (4700) and χc(4P,5P) States

We study some of the main properties (masses and open-flavor strong decay widths) of 4P and 5P charmonia. While there are two candidates for the χc0(4P,5P) states, the X(4500) and X(4700), the properties of the other members of the χc(4P,5P) multiplets are still completely unknown. With this in mind, we start to explore the charmonium interpretation for these mesons. Our second goal is to investigate if the apparent mismatch between the Quark Model (QM) predictions for χc0(4P,5P) states and the properties of the X(4500) and X(4700) mesons can be overcome by introducing threshold corrections in the QM formalism. According to our coupled-channel model results for the threshold mass shifts, the χc0(5P)→X(4700) assignment is unacceptable, while the χc0(4P)→X(4500) or X(4700) assignments cannot be completely ruled out.

Investigation of $$\varXi _c^0$$ in a chiral quark model

Recently, three new states of $$\varXi _c^0$$ Ξ c 0 were observed in the invariant mass spectrum of $$\varLambda ^+_cK^-$$ Λ c + K - by LHCb collaboration. In this work, we use a chiral quark model to investigate these three exited states with the help of Gaussian expansion method both in three-quark structure and in five-quark structure with all possible quantum numbers $$IJ^P=\frac{1}{2}(\frac{1}{2})^-$$ I J P = 1 2 ( 1 2 ) - , $$\frac{1}{2}(\frac{3}{2})^-$$ 1 2 ( 3 2 ) - , $$\frac{1}{2}(\frac{5}{2})^-$$ 1 2 ( 5 2 ) - , $$\frac{3}{2}(\frac{1}{2})^-$$ 3 2 ( 1 2 ) - , $$\frac{3}{2}(\frac{3}{2})^-$$ 3 2 ( 3 2 ) - and $$\frac{3}{2}(\frac{5}{2})^-$$ 3 2 ( 5 2 ) - . The calculations shows that the masses of 2S and 1D states of $$\varXi _c$$ Ξ c are comparable to experimental results; In addition, the resonance states of five-quark configuration are possible candidates of these new states with negative parity by using the real scaling method and their decay width is also given.

A GPU Based Multidimensional Amplitude Analysis to Search for Tetraquark Candidates

The demand for computational resources is steadily increasing in experimental high energy physics as the current collider experiments continue to accumulate huge amounts of data while physicists indulge in more complex and ambitious analysis strategies. This is especially true in the fields of hadron spectroscopy and flavour physics where the analyses often depend on complex multidimensional unbinned maximum-likelihood fits, with several dozens of free parameters, with the aim to study the quark structure of hadrons. Graphics processing units (GPUs) represent one of the most sophisticated and versatile parallel computing architectures that are becoming popular toolkits for high energy physicists to meet their computational demands. GooFit is an upcoming open-source tool interfacing ROOT/RooFit to the CUDA platform on NVIDIA GPUs that acts as a bridge between the MINUIT minimization algorithm and a parallel processor, allowing probability density functions to be estimated on multiple cores simultaneously. In this article, a full-fledged amplitude analysis framework developed using GooFit is tested for its speed and reliability. The four-dimensional fitter framework, one of the firsts of its kind to be built on GooFit, is geared towards the search for exotic tetraquark states in the [[EQUATION]] decays that can also be seamlessly adapted for other similar analyses. The GooFit fitter running on GPUs shows a remarkable speed-up in the computing performance when compared to a ROOT/RooFit implementation of the same, running on multicore CPU clusters. Furthermore, it shows sensitivity to components with small contributions to the overall fit. It has the potential to be a powerful tool for sensitive and computationally intensive physics analyses.

Role of Quarks in Nuclear Structure

The strong force that binds atomic nuclei is governed by the rules of Quantum Chromodynamics. Here we consider the suggestion the internal quark structure of a nucleon will adjust self-consistently to the local mean scalar field in a nuclear medium and that this may play a profound role in nuclear structure. We show that one can derive an energy density functional based on this idea, which successfully describes the properties of atomic nuclei across the periodic table in terms of a small number of physically motivated parameters. Because this approach amounts to a new paradigm for nuclear theory, it is vital to find ways to test it experimentally and we review a number of the most promising possibilities.

K+Λ(1405) photoproduction at the BGO-OD experiment

Since the discovery of the Λ(1405), it remains poorly described by conventional constituent quark models, and it is a candidate for having an “exotic” meson-baryon or “penta-quark” structure, similar to states recently reported in the hidden charm sector. The Λ(1405) can be produced in the reaction γp K+Λ(1405). The pure I=0 decay mode into Σ0π0 is prohibited for the mass-overlapping Σ(1385). Combining a large aperture forward magnetic spectrometer and a central BGO crystal calorimeter, the BGO-OD experiment is ideally suited to measure this decay with the K+ in the forward direction. Preliminary results are presented. *Supported by DFG (PN 388979758, 405882627)

Radiative decays and the SU(6) Lie algebra

We present research on radiative decays of vector [Formula: see text] to pseudoscalar [Formula: see text] particles ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] quark system) using broken symmetry techniques in the infinite-momentum frame and equal-time commutation relations and the [Formula: see text] Lie algebra, and conducted without ascribing any specific form to meson quark structure or intra-quark interactions. We utilize the physical electromagnetic current [Formula: see text] including its singlet [Formula: see text] term and focus on the [Formula: see text] 35-plet. We derive new relations involving the electromagnetic current (including its singlet — proportional to the [Formula: see text] singlet). Remarkably, we find that the electromagnetic current singlet plays an intrinsic role in understanding the physics of radiative decays and that the charged and neutral [Formula: see text] meson radiative decays into [Formula: see text] are due entirely to the singlet term in [Formula: see text]. Although there is insufficient radiative decay experimental data available at this time, parametrization of possible predicted values of [Formula: see text] is made. For conciseness and self-containment, we compute all [Formula: see text] Lie algebra simple roots, positive roots, weights and fundamental weights which allow the construction of all [Formula: see text] representations. We also derive all nonzero [Formula: see text] generator commutators and anticommutators — useful for further research on grand unified theories.

Pion assisted dibaryons: the d*(2380) resonance

The structure and width of the recently established d*(2380) resonance are discussed, confronting the consequences of a Pion Assisted Dibaryons hadronic model with those of quark motivated calculations. In particular, the small width $\Gamma_{d\ast}\approx70$ MeV favors hadronic structure for the d*(2380) dibaryon rather than a six-quark structure.