Hadron Spectroscopy Research Articles

Hadron spectroscopy in LHCb

The LHCb experiment is designed to study the properties and decays of heavy flavored hadrons produced in pp collisions at the LHC. The data collected in the LHC Run I enables precision spectroscopy studies of beauty and charm hadrons. The latest results on spectroscopy of conventional and exotic hadrons are reviewed. In particular the discovery of the first charmonium pentaquark states in theJ/Ψpsystem, the possible existence of four-quark states decaying toJ/ΨΦand the confirmation of resonant nature of theZc(4430)−mesonic state are discussed. In the sector of charmed baryons, the observation of five new Ωcstates, the observation of the Ξcc+and the study of charmed baryons decaying toD0pare presented.

BESIII future prospects in exotic hadron spectroscopy

Recent BESIII results on exotic hadron candidates, the heavy charmonium-like states, will be reviewed, as well as a short introductions to the BEPCII collider and the BEESIII detector. Future BESIII running plans, specially the physics program for the exotic hadron spectroscopy, will be discussed.

PANDA Muon System Prototype

The PANDA Experiment will be one of the key experiments at the Facility for Antiproton and Ion Research (FAIR) which is under construction now in the territory of the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. PANDA is aimed to study hadron spectroscopy and various topics of the weak and strong forces. Muon System is chosen as the most suitable technology for detecting the muons. The Prototype of the PANDA Muon System is installed on the test beam line T9 at the Proton Synchrotron (PS) at CERN. Status of the PANDA Muon System prototype is presented with few preliminary results.

Heavy-hadron interactions from Lattice QCD

I review recent progress in heavy hadron spectroscopy and from ab-initio Lattice QCD calculations.After motivating lattice calculations for heavy-hadrons by contrasting recent LHCb results charmed and doubly-charmed baryons with lattice predictions, selected resultsfrom scattering calculations for heavy-light mesons and for charmonia are presented.I close with a discussion of recent Lattice QCD predictions of explicitlyexotic doubly-heavy states.

Light Hadron Spectroscopy at BESIII

The BESIII has collected 1.3 billion J/ψ and 478 million ψ(3686) data since 2009. In this talk, we will introduce five recent analyses on light hadron spectroscopy at BESIII, including two studies on the X(1835), two partial wave analyses that are related to searching and studying glueball candidates, and one study on χc1.

Light Hadron Spectroscopy at BESIII

BESIII has collected [Formula: see text] and [Formula: see text] of [Formula: see text], which are the world’s largest data samples of [Formula: see text] and [Formula: see text] from [Formula: see text] collision. Radiative decays of charmonium provide a gluon-rich environment and are therefore regarded as one of the most promising hunting grounds for gluonic excitations. Significant progresses in the light-quark sector have been made with the unprecedented high statistics data sets. Several recent results on light hadron spectroscopy and light hadron decays will be reported, including: 1, the observation of the anomalous line shape of [Formula: see text] near [Formula: see text] mass threshold and related studies; 2, studies of glueballs in [Formula: see text] radiative decays; 3, search for [Formula: see text] exotic in [Formula: see text].

Recent developments in charmed baryon spectroscopy

An overview of recent developments in charmed baryon spectroscopy is given. The classification of charmed baryons is presented, a quark model for ground states is briefly described, and the energy levels of excited states are analyzed.

Performance studies of the [formula omitted]ANDA planar GEM-tracking detector in physics simulations

The P¯ANDA experiment will be installed at the future facility for antiproton and ion research (FAIR) in Darmstadt, Germany, to study events from the annihilation of protons and antiprotons. The P¯ANDA detectors can cover a wide physics program about baryon spectroscopy and nucleon structure as well as the study of hadrons and hypernuclear physics including the study of excited hyperon states. One very specific feature of most hyperon ground states is the long decay length of several centimeters in the forward direction. The central tracking detectors of the P¯ANDA setup are not sufficiently optimized for these long decay lengths. Therefore, using a set of the planar GEM-tracking detectors in the forward region of interest can improve the results in the hyperon physics-benchmark channel. The current conceptual designed P¯ANDA GEM-tracking stations contribute the measurement of the particles emitted in the polar angles between about 2 to 22 degrees. For this designed detector performance and acceptance, studies have been performed using one of the important hyperonic decay channel p¯p→Λ¯Λ→p¯pπ+π− in physics simulations. The simulations were carried out using the PandaRoot software packages based on the FairRoot framework.

Spectroscopy of exotic hadrons formed from dynamical diquarks

The dynamical diquark picture asserts that exotic hadrons can be formed from widely separated colored diquark or triquark components. We use the Born-Oppenheimer (BO) approximation to study the spectrum of states thus constructed, both in the basis of diquark spins and in the basis of heavy quark-antiquark spins. We develop a compact notation for naming these states, and use the results of lattice simulations for hybrid mesons to predict the lowest expected BO potentials for both tetraquarks and pentaquarks. We then compare to the set of exotic candidates with experimentally determined quantum numbers, and find that all of them can be accommodated. Once decay modes are also considered, one can develop selection rules of both exact ($J^{PC}$ conservation) and approximate (within the context of the BO approximation) types and test their effectiveness. We find that the most appealing way to satisfy both sets of selection rules requires including additional low-lying BO potentials, a hypothesis that can be checked on the lattice.

Novel MPGD based detectors of single photons in COMPASS RICH-1

COMPASS is a fixed target experiment at CERN SPS aimed to study Hadron Structure and Spectroscopy. Hadron Identification in the momentum range between 3 and 55 GeV/c is provided by a large gaseous Ring Imaging Cherenkov Counter (RICH-1). To cope with the challenges imposed by the new physics program of COMPASS, RICH-1 has been upgraded by replacing four MWPCs based photon detectors with newly developed MPGD based photon detectors. The architecture of the novel detectors is a hybrid combination of two layers of THGEMs and a MicroMegas. The top of the first THGEM is coated with CsI acting as a reflective photo-cathode. The anode is segmented in pads capacitively coupled to the APV-25 based readout. The new hybrid detectors have been commissioned during 2016 COMPASS data taking and stably operated during 2017 run. In this paper all aspects of the novel photon detectors for COMPASS RICH-1 are discussed.

Delocalized SYZ mirrors and confronting top\u2013down SU(3)-structure holographic meson masses at finite g and N_c with P(article) D(ata) G(roup) values

Meson spectroscopy at finite gauge coupling – whereat any perturbative QCD computation would break down – and finite number of colors, from a top–down holographic string model, has thus far been entirely missing in the literature. This paper fills this gap. Using the delocalized type IIA SYZ mirror (with SU(3) structure) of the holographic type IIB dual of large-N thermal QCD of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) as constructed in Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at finite coupling and number of colors (N_c = number of D5(overline{D5})-branes wrapping a vanishing two-cycle in the top–down holographic construct of Mia et al. (Nucl Phys B 839:187. arXiv:0902.1540 [hep-th], 2010) = mathcal{O}(1) in the IR in the MQGP limit of Dhuria and Misra (JHEP 1311:001. arXiv:1306.4339 [hep-th], 2013) at the end of a Seiberg-duality cascade), we obtain analytical (not just numerical) expressions for the vector and scalar meson spectra and compare our results with previous calculations of Sakai and Sugimoto (Prog Theor Phys 113:843. doi:10.1143/PTP.113.843. arXiv:hep-th/0412141, 2005) and Dasgupta et al. (JHEP 1507:122. doi:10.1007/JHEP07(2015)122. arXiv:1409.0559 [hep-th], 2015), and we obtain a closer match with the Particle Data Group (PDG) results of Olive et al. (Particle Data Group) (Chin Phys C 38:090001, 2014). Through explicit computations, we verify that the vector and scalar meson spectra obtained by the gravity dual with a black hole for all temperatures (small and large) are nearly isospectral with the spectra obtained by a thermal gravity dual valid for only low temperatures; the isospectrality is much closer for vector mesons than scalar mesons. The black-hole gravity dual (with a horizon radius smaller than the deconfinement scale) also provides the expected large-N suppressed decrease in vector meson mass with increase of temperature.

Determination of at five loops from holographic QCD

The recent determination of the β-function of the quantum chromodynamics (QCD) running coupling to five-loops, provides a verification of the convergence of a novel method for determining the fundamental QCD parameter based on the light-front holographic approach to nonperturbative QCD. The new five-loop analysis, together with improvements in determining the holographic QCD nonperturbative scale parameter κ from hadronic spectroscopy, leads to an improved precision of the value of in the scheme close to a factor of two; we find for , in excellent agreement with the world average, . We also discuss the constraints imposed on the scale dependence of the strong coupling in the nonperturbative domain by superconformal quantum mechanics and its holographic embedding in anti-de Sitter space.

Observation of the B+→D*−K+π+ decay

The $B^+ \to D^{*-}K^+\pi^+$ decay potentially provides an excellent way to investigate charm meson spectroscopy. The decay is searched for in a sample of proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3~{\rm fb}^{-1}$. A clear signal is observed, and the ratio of its branching fraction to that of the $B^+ \to D^{*-}\pi^+\pi^+$ normalisation channel is measured to be \begin{equation*} \frac{\mathcal{B}(B^+ \to D^{*-}K^+\pi^+)}{\mathcal{B}(B^+ \to D^{*-}\pi^+\pi^+)} = \left( 6.39 \pm 0.27 \pm 0.48 \right) \times 10^{-2} \, , \end{equation*} where the first uncertainty is statistical and the second is systematic. This is the first observation of the $B^+ \to D^{*-}K^+\pi^+$ decay.

New Insights into Color Confinement, Hadron Dynamics, Spectroscopy, and Jet Hadronization from Light-Front Holography and Superconformal Algebra

A fundamental problem in hadron physics is to obtain a relativistic color-confining, first approximation to QCD which can predict both hadron spectroscopy and the frame-independent light-front (LF) wavefunctions underlying hadron dynamics. The QCD Lagrangian with zero quark mass has no explicit mass scale; the classical theory is conformally invariant. Thus, a fundamental problem is to understand how the mass gap and ratios of masses – such as m ρ/m p – can arise in chiral QCD. De Alfaro, Fubini, and Furlan have made an important observation that a mass scale can appear in the equations of motion without affecting the conformal invariance of the action if one adds a term to the Hamiltonian proportional to the dilatation operator or the special conformal operator and rescales the time variable. If one applies the same procedure to the light-front Hamiltonian, it leads uniquely to a confinement potential κ 4 ζ 2 for mesons, where ζ 2 is the LF radial variable conjugate to the $$ q\overline{q} $$ invariant mass squared. The same result, including spin terms, is obtained using light-front holography – the duality between light-front dynamics and AdS5, the space of isometries of the conformal group if one modifies the action of AdS5 by the dilaton $$ {e}^{\kappa^2}{z}^2 $$ in the fifth dimension z . When one generalizes this procedure using superconformal algebra, the resulting light-front eigensolutions predict unified Regge spectroscopy of meson, baryon, and tetraquarks, including remarkable supersymmetric relations between the masses of mesons and baryons of the same parity. One also predicts observables such as hadron structure functions, transverse momentum distributions, and the distribution amplitudes defined from the hadronic light-front wavefunctions. The mass scale κ underlying confinement and hadron masses can be connected to the parameter $$ {\Lambda}_{\overline{MS}} $$ in the QCD running coupling by matching the nonperturbative dynamics to the perturbative QCD regime. The result is an effective coupling α s (Q 2) defined at all momenta. The matching of the high and low momentum transfer regimes also determines a scale Q0 which sets the interface between perturbative and nonperturbative hadron dynamics.

The baryon spectroscopy: strong decays and strange suppression11Invited talk presented at Symposium on Nuclear Physics, January 4-7 2017, Cocoyoc(Mexico).

In this contribution, we present the open-flavor strong decays of light baryons computed within the framework of quark model. The transition amplitudes are computed using a modified operator, where a mechanism strange suppression is taken into account. Also we discus the strange suppression within an extension of the quark model.

Spectroscopy of light baryons in a semi-relativistic constituent three-quark model

We studied the non-strange baryon spectroscopy by presenting a simple semi-relativistic constituent three-quark model. Assuming a separation of the interaction potential in terms of a leading SU(6) symmetric component and a subleading SU(6) breaking term, we treated the baryons as a spin-independent three-quark system and presented the analytical solution for the problem. Using perturbative and approximative approaches in order to deal with problematic linear confining term in SU(6)-invariant interaction, we obtained analytical formulas for energy levels and the hyperradial wave functions and the average energy values of the nonstrange resonances are reproduced. To describe the hyperfine structure of the baryon, the splittings within the SU(6)-multiplets are produced by the perturbative spin- and isospin-dependent terms. The resulting description of the baryon spectrum for both approaches are given and compared with the experimental spectrum.

Hadron structure and spectroscopy at COMPASS. Overview of certain tasks

COMPASS is a fixed-target experiment at CERN with a long history and intense and diverse physics programme. In the Review we consider particular points of the existing and possible future programme: test of the chiral theory predictions with hadron beam, search for exotic charmonia, study of the EMC effect in the Drell–Yan process, search for production of bound \(p\overline p \) states and study of prompt photon production in hadronic interactions.

Effect of the extra dimensions on the meson spectra in the perturbed background

A class of the d-dimensional black holes space-time with the perturbed geometric function and dilaton field is considered to study meson spectroscopy. Holographic description of the black holes are used to investigate the meson spectra and the effective potential of mesons which described by a massless scalar field in the d-dimensional black holes with a dilaton background. The effects of perturbations and extra dimensions on the meson spectra and effective potential are investigated by using some experimental data and simulation of spectra ratios.

Quarkonium Studies at COMPASS Experiment

COMPASS is a fixed-target experiment with wide scientific programme. The main objectives are nucleon structure studies and hadron spectroscopy. A short overview of the physics programme and the apparatus is given. Then, three measurements that have a relation to quarkonium are highlighted and briefly described: a determination of limits on the exotic resonance \(\mathrm {Z}_\mathrm {c}^\pm (3900)\) branching ratio and partial width; study of the gluon Sivers asymmetry in leptoproduction of \(\mathrm {J}/\psi \) resonance and finally the first-ever study of the Drell–Yan process with a transversely polarised target.

Overview on BESIII Recent Results

The BESIII experiment in Beijing started data taking for physics since 2009. Based on these data samples, the recent results from BESIII experiment, including the study of light hadron spectroscopy, XYZ particles, precision measurement of charm physics, are presented in this report.