Heavy quark baryons provide an excellent laboratory for tests of effective theories of the strong interaction. Recently a wealth of data on those systems has become available at the large hadron collider, such as the first observation of a doubly-charmed baryon, several new $\Omega_c$ states and exotic baryons with hidden charm. For beauty-baryons these new data allow precision measurements of...
Some experimental approaches involving spectroscopy from heavy meson decays going to light mesons will be presented. Along with this, we will display several experimental results coming from J/Psi, D and B decays with a particular emphasis to the scalar resonance f0(980). We will also show how the CP violation observed in charmless three body decay can be used as tool to understand hadron...
Low-energy experiments with hadrons can identify physics beyond the Standard Model (SM), through either the observation of an unexpected breaking of its symmetries or that of a significant departure from a precise SM prediction. I will review some possibilities and highlight new opportunities for the discovery of new sources of CP violation and of light, weakly coupled new physics.
We discuss the present status of the determination and measurement of the low moments of the proton tested by the electromagnetic interactions: Proton radius, Zemach moments, two-photon exchange corrections, etc... Special attention is paid to understanding their chiral structure and to give a unified description of all of them by relating them with Wilson coefficients of effective field...
The Joint Physics Analysis Center (JPAC) was formed in 2013 to develop theoretical and phenomenological methods that would lead to a better understanding of production and decays of hadron resonances. JPAC does not rely on a single model or approach, but it is inclusive to various methodologies. JPAC products not only provide a better understanding of hadron phenomena but are of direct use in...
The observation of two pentaquark resonances and the proof of the resonant nature of the Zc state opened to the search for the many isospin partner of these multi-quark states. We review the studies of these states and discuss the prospects for the analyses of the LHCb Run2 data,
This talk will discuss recent results from the CLAS Collaboration of interest to the Hadron Physics community. This will include a number of recent publications on the topic of hadron spectroscopy and also some information about upcoming hadron physics experiments planned at CLAS12. In particular, new results from two-pion electroproduction will be compared with calculations, in a search for...
Measurements of the ratio of the elastic form factors of the proton ($\mu_pG_E/G_M$) exhibit
a strong discrepancy. Experiments using unpolarized beams and Rosenbluth separation
to determine the form factors consistently have found values of the ratio approximately consistent
with unity over a wide range of $Q^2$, while polarization transfer experiments suggest that the ratio
decreases as a...
The constituent quark model (CQM) describes the nucleon as a system of three constituent, or valence, quarks. Despite the successes of the CQM (e.g. masses, electromagnetic couplings, and magnetic moments), there is compelling evidence for the presence of sea quarks from other observables such as the observed flavor asymmetry of the proton, the proton spin crisis, and the systematics of strong...
The use of covariant formalisms in amplitude analysis is becoming more and more popular among the experimental collaborations. We discuss some of the tensor formalisms available in the literature, and check whether or not they satisfy the $S$-matrix constraints. We match these to the usual helicity amplitudes, showing that there is no need for "relativistic" corrections.
A general approach to the construction of bound states in quantum field theory, called the renormalization group procedure for effective particles (RGPEP), is applied to single heavy-flavor QCD in order to study its utility beyond illustration of its general features. This heavy-flavor QCD is chosen as the simplest available context in which the dynamics of quark and gluon bound states can be...
I will discuss recent progress in studying the spectra of mesons using first-principles lattice QCD calculations. In particular, some results on excited mesons, resonances and related phenomena in the light and heavy sectors will be highlighted, including work relevant for puzzling/exotic states such as the Ds(2317). I will also comment on future prospects.
Hadrons have several remarkable features, which call for an understanding within QCD. In addition to confinement and chiral symmetry breaking these include:
- Hadrons can generally be classified as $q\bar{q}$ or $qqq$ states. Sea quarks and gluons do not enrich the spectrum. Heavy quarkonia ($c\bar{c}$, $b\bar{b}$) are well described by the Schr\"odinger equation with a...
We have studied the production and decay of the f1(1285) into πa0(980) and KK¯ as a function of the mass of the resonance and find a shoulder around 1400 MeV, tied to a triangle singularity, for the πa0(980) mode, and a peak around 1420 MeV with about 60 MeV width for the KK¯ mode. Both these features agree with the experimental information on which the f1(1420) resonance is based.
In...
The BGO-OD experiment at the ELSA accelerator facility uses an
energy tagged bremstrahlung photon beam to investigate the internal
structure of the nucleon. The setup consists of a highly segmented BGO
calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles.
BGO-OD is ideal for investigating the photoproduction of hadrons of
non-zero strangeness....
Implications of heavy-quark spin-symmetry (HQSS) are investigated for the isoscalar charmonium-like state $X(3872)$ and the isovector bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$ under the assumption of the latter being bound states of the nearby heavy meson-antimeson pairs (see Refs. [1,2] for more details). We formulate and solve a system of the integral equations for a...
We use Regge phenomenology and the structure of the hyperon ($\Lambda$ and $\Sigma$) spectrum to gain insight on the nature of the two $\Lambda$(1405) resonances. We find that only of these resonances is compatible with a three-quark state.
The determination of the pion form factor to high Q^2 provides an important measure of the transition to quark and gluon degrees of freedom in hadrons. Its measurement to Q^2 in excess of 6 GeV^2 is an approved experiment of the 12 GeV upgrade. In this talk, we present recent progress aimed at computing the pion form factor in lattice QCD to values of Q^2 commensurate with the upcoming...
We have analyzed the singularities of a triangle loop integral in detail and derived a formula for an easy evaluation of the triangle singularity on the physical boundary. It is applied to the Λb→J/ψK−p process via Λ∗-charmonium-proton intermediate states. Although the evaluation of absolute rates is not possible, we identify the χc1 and the ψ(2S) as the relatively most relevant states among...
We present our predictions for pion mean charge radius, decay constant, spacelike electromagnetic form factor, twist-2 Distribution Amplitude and the photon-to-pion transition form factor when a dynamical spin structure for the pseudoscalar particle is considered along with a holographic light-front wavefunction. Our results show significant improvement in agreement with available data.
We have recently studied the interaction of meson-baryon systems with strangeness -2 and our results explain why some Xi-baryons are narrower than expected. For instance, the latest BABAR and BELLE data show that the width of Ξ(1690) is of the order of 10 MeV. With our coupled channel calculation of the pseudoscalar meson-baryon and vector meson-baryon systems with chiral and hidden local...
The main purpose of scattering experiments is to unveil
the underlying structure of the colliding particles. Typically
one has scattering observables at discrete angles and energies and
some decision has to be made on what are the maximal amount of data which are
mutually compatible among themselves and with a sufficiently flexible model with a minimal number of theoretical assumptions. We...
At J-PARC, we are conducting spectroscopic studies of strangeness -2 systems, such as Ξ- and double-Λ hypernuclei. The experimental information on these systems is so far
limited with several emulsion events; the “Nagara” event for ΛΛ6He and the “Kiso” event
for a strong candidate of a Ξ hypernucleus. In this talk, I will introduce a preliminary result
on Ξ12Be obtained in the pilot run of E05...
LHCb continues to expand its world-leading sample of charmed hadrons collected during LHC’s 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. LHCb’s latest work on the spectroscopy of charmed hadrons is presented.
The Generalized Polarizabilities are fundamental quantities of the nucleon and as such they are extremely valuable for a more complete understanding of the nucleon structure. The GPs can be accessed experimentally through measurements of the Virtual Compton Scattering reaction. They can be seen as Fourier transforms of local polarization densities (electric, magnetic, and spin) and therefore...
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).
Partial-wave analysis of meson and photon-induced reactions is needed to enable the comparison of many theoretical approaches to data. In both energy-dependent and independent parametrizations of partial waves, the selection of the model amplitude is crucial. Principles of the S matrix are implemented to a different degree in different approaches; but a many times overlooked aspect concerns...
It is important to study \Xi N interaction in hypernuclear physics. However, due to no \Xi N scattering data, it is essentail to study \Xi hypernuclei. Recently, we observed a \Xi hypernuclues,called as Kiso event, to have a bound state for the first time. From this data, we found that \Xi N interaction should be attractive. In this conference, we discuss that what kind of \Xi N interaction...
In this talk I will show how to combine Chiral EFT and dispersion theory in order to get an improved prediction of the form factors of the nucleon. As an example, I will show the case of the scalar and electromagnetic form factors, and how the chiral prediction, improved with dispersion theory, shows an excellent agreement with independent determinations from purely dispersive calculations
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.
The framework of BChPT combined with the 1/Nc expansion is implemented for three flavors and applied to the octet and decuplet baryon masses and currents. Results to one-loop in the chiral expansion, and subleading order in the 1/Nc expansion will be presented. Particular emphasis will be made on the improvements resulting from the constraints implied by consistency with the 1/Nc expansion....
It is well known that unconstrained single-energy partial wave analysis (USEPWA) gives many equivalent discontinuous solutions, so a constraint to some theoretical model must be used to ensure the uniqueness. It can be shown that it is a direct consequence of not specifying the angle-dependent part of continuum ambiguity phase which mixes multipoles, and by choosing this phase we restore the...
In the last decade, heavy-ion collision experiments have brought new insight to the study of (anti-)hypernuclei. Experiments using heavy ion collisions for hypernuclear research focus on two distinct aspects: the production mechanism and the lifetime estimation, in particular for the hypetriton. The ALICE experimental observations which allow to test models of the production mechanism...
We lay out a framework that can be used to obtain estimates of the possible impact of (com-
binations) of polarization measurements in pseudoscalar-meson photoproduction from the nucleon.
To this end, we quantify the distance between models for pseudoscalar-meson photoproduction in
amplitude space. Experimental observables, with finite accuracy, map to probability distributions
in amplitude...
Probing elementary symmetries and symmetry breaking tests our understanding of the theory of strong forces, Quantum Chromodynamics. Investigations of charge symmetry breaking is one of the primary goals for the WASA-at-COSY experiment. The presented study concentrates on the charge symmetry forbidden reaction $dd \to {}^4\text{He}\pi^0$.
The aim is to provide experimental results for...
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...
With various experiments studying heavy-ion collisions a demand exists in the hadron physics community for theoretical predictions of hadronic properties at temperatures and densities far from standard nuclear physics scenarios. In this work we will study the implications of light-quark mesonic matter at finite temperatures on the open and hidden charm mesons. We will apply a chiral unitary...
Important contributions to the study of the excitation spectra of
baryons are provided by measurements of polarization observables
in reactions that involve particles with spin. Pseudoscalar meson
photoproduction poses an example-reaction that has been under intense
investigation recently.
The extraction of resonance-parameters from the polarization-data in
so-called energy-dependent fits,...
Electromagnetic form factors of baryon provide fundamental information about its structure and dynamics. They constitute a rigorous test of nonperturbative QCD as well as of phenomenological models. Using data samples collected with BESIII detector at BEPCII collider, We measure Born cross section of e+e- -> ppbar at center-of-mass energy between 2.0GeV and 3.08GeV. The ratio |GE/GM| and |GM...
We investigate the in-medium masses of a $\bar{D}$ $(0^-)$ meson and a $\bar{D}_0^*$ $(0^+)$ meson, and spectral functions for $\bar{D}$
and $\bar{D}_0^*$
meson channels in nuclear matter.
These mesons are introduced as chiral partner in the chiral symmetry broken vacuum,
hence they are useful to explore the partial restoration of the broken chiral symmetry in nuclear matter.
We consider...
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 spectrum of light-quark (uds) mesons has been studied since the mid-20th century, yet these simplest of hadrons are still providing new insight into the nature of the strong interaction and presenting new experimental challenges. In this talk, I will discuss the current status of light mesons, show some of the most exciting new results in this area, and discuss the prospects for future...
In this talk I will give a general overview on recent results from several groups
on the spectrum and properties of three- and four-quark states as obtained
in the framework of Dyson-Schwinger and Bethe-Salpeter equations.
I will discuss the spectrum of light baryons with focus on the comparison with
quark model expectations, the impact of dynamical mass generation and explain
the importance...
In recent years we have seen significant progress in our ability to study scattering reactions and resonances using lattice QCD. Quantities that were previously believed to be inaccessible from lattice QCD (e.g., scattering amplitudes of coupled-channel systems) are now being rigorously studied. For some reactions, the procedure for accessing amplitudes and their corresponding resonance...
Results for baryon spectroscopy by different collaborations and, generally, the state of the art in the subfield will be reviewed. Highlights contain common efforts of different phenomenology groups and the impact of recent high-precision data from ELSA, JLab, MAMI, and other facilities. Questions will be addressed of how to proceed to reach conclusive answers in baryon spectroscopy, on one...
I review recent results on dispersive analyses of pion-pion and kaon-pion amplitudes and the extraction of resonance parameters using dispersion relations or analytic methods
In the past decade many charmonium-like states were observed experimentally, including many charmonium-like XYZ states and the hidden-charm pentaquark states Pc(4380) and Pc(4450). We systematically investigate their mass spectra using the method of QCD sum rules. Especially, we pay attention to their internal structure by constructing all the relevant local hidden-charm tetraquark and...
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...
A strongly interacting state of matter known as the Quark-Gluon Plasma (QGP) is formed in the high temperature and energy density conditions reached in ultra-relativistic heavy-ion collisions. One of the key measurements for the understanding of the thermal properties of the fireball created in these collisions is the study of the production of strange and particularly multi-strange hadrons in...
The resonant substructure of the four-body decays D0→π+π−π+π− and D0→K+K−π+π− 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)+, π(1300)+ and a1(1640)+ are studied in...
Measurements of charmed-hadron production in pp collisions are important to test predictions from perturbative QCD and provide an essential baseline for the studies in A--A collisions. Measurements in p--A collisions also allow studies of possible modifications of the charmed-hadron yields due to cold nuclear matter effects. The study of charm production as a function of the multiplicity of...
The BESIII Experiment at the Beijing Electron Positron Collider (BEPC2) has accumulated the world's largest samples of e+e- collisions in the tau-charm region. Cross sections of e+e- --> pi+pi- psi(2S) above 4.0 GeV, and a charged structure has been observed in the pi psi(2S) mass spectrum. Cross sections of e+e- --> KKbar J/psi between 4189 and 4600 MeV. Compared with pi+ pi- J/psi, more...
In the so-called isobar ansatz the three-particle states can only be populated
via an interacting two-particle system (resonant or non-resonant), and a spectator.
Using this ansatz, we derive the isobar-spectator interaction such that the
three-body unitarity is ensured exactly.
Some of the final equations are similar to the old Amado/Aaron/Young appoach,
however do not rely on arguments...
A precise understanding of low-energy pion-nucleon interactions is central for many areas in nuclear and hadronic physics, ranging from the scalar couplings of the nucleon to the long-range part of two-pion-exchange potentials and three-nucleon forces in Chiral Effective Field Theory. We present a calculation that combines the general principles of analyticity, unitarity, and crossing symmetry...
Presently the study of the phase diagram of QCD is the subject of both theoretical and experimental studies under extreme conditions of density and temperature.
In particular, it is expected that the phenomenon of deconfinement occurs in
relativistic heavy-ion collisions and in the interior of compact stars.
Also the understanding of the effect of an external magnetic field on the structure...
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 ...
We investigate the resonance-like structure with quantum numbers $J^{PC} = 1^{++}$ in the $f_{0}\pi$ P-wave recently observed at a mass $1.4\,$GeV by the COMPASS Collaboration. The signal was tentatively assigned to be an axial resonance, $a_{1}(1420)$, although it does not fit the $q\bar{q}$-model, which suggests an exotic nature. We present an elegant explanation of the phenomenon without...
Interaction cross-sections for baryon pairs are of fundamental interest
and they are actively investigated theoretically. They are known well for
pairs of common (anti-)baryons, however there is a lack of precise
experimental data for heavier baryons, including the ones carrying strangeness. The
two-particle correlation formalism (femtoscopy) is sensitive to the
interaction kernel for a pair...
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 $u\overline{u}c\overline{c}$, $u\overline{u}b\overline{b}$, and $u\overline{u}s\overline{s}$ $J^{PC}=1^{--}$ states are investigated by a coupled-channel two-meson model. We used the complex scaling method with 14 two-meson channels with an effective hadron interaction originated from interaction between quarks. The coupling between channels is obtained from the quark rearrangement.
We...
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...
I will present the recent work [Phys Rev D94(2016) 096015] about the a1(1420) peak which is experimentally and theoretically interesting. We study the decay mode of the a1(1260) into a pi+ in p-wave and the f0(980) that decays into pi+ pi- in s-wave. The mechanisms proceeds via a triangular mechanism where the a1(1260) decays into Kbar K, the K decays to an external pi+ and an internal K that...
A large number of exotic candidates, especially in the heavy sector,
have being observed in experiment, such as Zc(3900), Zc(4020), Pc(4380),
Pc(4450), X(5568) and so on. To understand their nature, numerous explanations
are proposed within different frameworks. I will give an overall review of the status of these studies and emphasize key issues to be answered by these solutions.
Crucial...
The Standard Model makes a definite prediction for the neutral weak charge of
the proton; deviation from this value would be a signature of physics beyond
the Standard Model.
The Qweak experiment has determined the weak charge of the proton by measuring
the parity-violating asymmetry in elastic e-p scattering at
$Q^2=0.03\ (\mathrm{GeV}/c)^2$ with a total precision of less than 10 ppb.
The...
A comparison of experimentally observed excited nucleon states to phenomenological quark model predictions or lattice QCD calculations reveal large differences, especially concerning the number of excited states. An important tool to probe the nucleon excitation spectrum is the study of meson photoproduction reactions. In order to extract the contributing resonances from the experimental data...
Mesic nuclei in which a meson is bound by the strong interactions to atomic nuclei have been predicted for antikaons, eta and eta', omega and phi mesons, and for other mesons of mass above 1 GeV. While experimental searches are ongoing in several accelerator facilities for antikaons, eta and eta' mesons, no unambiguous identification of mesic nuclei has ever been achieved, partly owing to...
Photoproduction of $\eta$ and $\eta'$ on the nucleons was analyzed
within a new version of the $\eta$MAID model.
The model includes 23 nucleon resonances in the $s$ channel and $t$-channel
exchange of vector and axial-vector mesons with Regge cuts.
Parameters of the resonances were obtained from a fit to the new experimental data
of the A2 Collaboration and available data from CBELSA/TAPS,...
I will discuss the structure of the tetraquark candidate Zc(3900)
from the meson-meson coupled-channel scattering on the lattice.
The Zc(3900) is experimentally reported as a peak in the pi J/psi invariant mass
in the Y(4260)-->pi pi J/psi decay.
To understand the nature of the Zc(3900), it is most important
to extract the coupled pi J/psi - rho eta_c - anti-D D* interactions faithful to...
The BABAR Collaboration has an intensive program studying hadronic cross sections in low-energy $e^+e^-$ annihilations, which are accessible with data taken near the $\Upsilon(4{\mathrm{S}})$ via initial-state radiation.
Our measurements allow significant improvements in the precision of the predicted value of the muon anomalous magnetic moment.
These improvements are necessary for...
The understanding of the strong interaction between hadrons in the strangeness sector are an
important testing ground for chiral SU(3) symmetry due to the large mass of the strange quark.
The antikaon-nucleon interaction at low energy is studied using non-perturbative coupled-
channel techniques based on chiral SU(3) effctive Lagrangians.
With SIDDHARTA kaonic hydrogen and helium atoms were...
Several experiments have been devoted to the study of the antikaon properties within nuclear matter to understand the interaction between antikaons and nucleons at different density conditions. Experimental evidence delivered by kaonic atoms, kaon scattering data and the existence of the L(1405) resonance proves the antikaon-nucleon interaction to be attractive in the vacuum but the behavior...
We study the $\Lambda_c N - \Sigma_c N$ system on the basis of the coupled-channel HAL QCD method. The potentials are extracted from Nambu-Bethe-Salpeter wave functions on the lattice, which are faithful to S-matrix in QCD. One of the advantages of this approach is that it is possible to extract the potentials without any assumptions. I will present our results of the coupled-channel...
A powerful tool to investigate the properties of nucleon resonances is the detailed study of the excitation spectrum of the nucleons. It consists of many resonances which contribute with different strength to distinct decay channels. To obtain information about the contributing resonances,
the experimental measurement of several well chosen single
and double polarization observables is needed...
Using large data samples of di-muon events, CMS has performed detailed measurements in the field of double quarkonium production. In the double quarkonium final states potential resonances, such as heavy quark tetra-quarks governed by strong interaction, have been predicted. The first observation of Y(1S) pair production has been recently performed, with both quarkonia fully reconstructed from...
The CEBAF Large Acceptance Spectrometer (CLAS) housed in Hall B of the Thomas Jefferson Accelerator Facility provides us with the experimental tools to study strongly-interacting matter and its dynamics. Polarisation observables, accessible utilising polarised beams, allow us to performed detailed studies on the underlying dynamics of both initial and final state interactions as well as...
The measurement of the excitation spectrum of light-quark hadrons often requires to apply partial-wave analysis methods. The building blocks of the physical models used in such analyses are the partial waves, which are defined by the quantum numbers and the decay paths of the produced resonances. In diffractive dissociation reactions, in principle, infinitely many partial waves can contribute....
While QCD is regarded as a mature theory of interacting quarks, due to the complexity of the nucleon, a successful description of its spectrum of excited states remains a huge challenge. The photo-couplings to excited $N$* states provide benchmark tests for models. These require a determination of photo-production amplitudes and are extracted through detailed partial-wave analyses (PWA), which...
Recently, a peak structure was observed near the $K^- p p$ threshold in the in-flight ${}^3 {\rm He} (K^- , \Lambda p) n$ reaction of the E15 experiment at J-PARC. This peak could be a signal of the lightest kaonic nuclei, that is, the $\bar{K} N N (I=1/2)$ state, which has been intensively studied both experimentally and theoretically in the last decade. In this contribution we theoretically...
The production of mesons in proton-deuteron fusion has historically received considerable interest as a natural way to study the interaction between mesons and nuclear matter through final state interactions. Thus, the near threshold regions for the production of $\eta$ and $\pi^0$ mesons in $\text{p}\text{d} \rightarrow {}^3\text{He}X$ are already well explored, yet still subject of active...
We analyze here the mass spectrum of light vector and scalar mesons applying the novel approach developed in [1], where a modified soft wall model that includes a UV-cutoff at a finite z-position in the AdS space is used, thus introducing an extra energy scale. For this model, we found that the masses for the scalar and vector spectra are well fitted within $\delta_\text{RMS}=6.88\%$ for these...
Symmetry and symmetry breaking play significant roles in physics. In this contribution, we will discuss our recent progress on the emergent symmetry in dense nuclear matter which are hidden in the matter-free space. This discussion sheds light on the mechanisms of chiral symmetry breaking, scale symmetry breaking and also the flavor symmetry breaking.
Using the chiral unitary approach, combining with the heavy quark spin symmetry, we investigate the interactions of $J/\psi N$ with its coupled channels and look for the dynamical resonances in the interactions. One of the two $P_c$ states, $P_c (4450)$, found by LHCb experiments, is explained as a $\bar{D}^* \Sigma_c$ bound state in our theoretical model. To understand the properties of this...
$\eta$ and $\eta^\prime$ transition form factors and Padé approximants
We calculate two- and three-body decays of the (lightest) vector glueball into (pseudo)scalar,
(axial-)vector, as well as pseudovector and excited vector mesons in the framework of a model of
QCD. While absolute values of widths cannot be predicted because the corresponding coupling
constants are unknown, some interesting branching ratios can be evaluated by setting the mass of
the yet...
Counting hadronic states and QCD thermodynamics in a finite box are intimately
related. At small temperatures hadronic states are expected to saturate the partition
function, so, accepting the Particle Data Group (PDG) table [1] as the reference for
hadronic states, all the states listed by the PDG should also be counted as genuine
contributions to the QCD partition function and, hence,...
Hadrons composed of heavy quarks are the simplest ones to study in QCD.
They provide an affordable theoretical laboratory for investigating
the dynamics of gluons, mainly because quarks move slowly with respect
to each other as the sources of gluons and in the analysis of heavy meson
states one can safely take advantage of asymptotic freedom and expand
renormalized interactions in powers of...
We investigate (π0, η, η0) → γ∗γ transition form factors (TFFs) for both
space- and timelike regions using the light-front quark model. For the low
energy regime, we compare our LFQM results of the TFFs for low timelike
momentum transfer region and the slope parameters at q2 = 0 with the
recent experimental data from the Dalize decays of (π0, η, η0). For the high
energy regime, we show the...
The eta→3pi decays are a valuable source of information on low energy QCD. We present our updated results
for the extraction of the three flavor chiral symmetry breaking order parameters from these processes.
We use a Bayesian approach in the framework of resummed chiral perturbation theory to extract
information on the quark condensate and pseudoscalar decay constant in the chiral limit, as...
Following the discovery of the X(3872), several exotic states, collectively known as XYZ states, have recently been identified in the energy region of charmonium. Searches with proton-antiproton collisions, such as the upcoming PANDA experiment at FAIR, will play an essential role in the effort to shed light on the nature of these states, since the direct production mechanisms and high rates...
In binary neutron star mergers the dynamical backcoupling of the electroweak interaction to the neutron matter is relevant. To desribe this, a coupled non-perturbative treatment of both sectors is necessary. Functional methods, like Bethe-Salpeter-Equations and the Functional-Renormalization-Group can be used for this purpose. Since the dominant process is beta-decay, a first necessary step is...
We study thermal properties of a large-$N$ massless pion gas via a low-energy QCD approach given by an $O(N + 1)/O(N)$ nonlinear sigma model. In order to attain this, we build diagrammatically the associated free energy to $O(TM^{3})$ in the pion mass expansion through an effective vertex; we consider this since all its contributions coming from closed diagrams are to be taken into account. At...
The time projection chamber(HypTPC) has been developed for the H-dibaryon search experiment via (K-,K+) reactions at J-PARC. The high rate secondary beam up to 10^6 Hz from the world highest intensity proton beam should be taken into account. The HypTPC has the octagonal drift volume defined by the field cage, the cathode plane at the top and the amplification region at the bottom. The drift...
We use the Quark-Gluon String Model to obtain a quantitatively good description of the phi-meson production
experimental data in hadron-nucleon collisions on the spectra of secondary phi, as well as on the ratios of
phi/pi- and phi/K- production cross sections, for a wide energy region. We also consider the experimental
data on phi-meson production on nuclear targets, and we find that they...
The observation of the hidden-charm pentaquarks by the LHCb collaboration indicates an existence of exotic hadrons close to hidden-charm meson-baryon thresholds. In the literature, various model calculations have been performed such as the hadronic molecules and the compact multi-quark states. The observed states appear below the thresholds, and it indicates that the states are a loosely...
We investigate the two-flavor version of the extended linear sigma model (eLSM), which contains, besides the standard scalar and pseudoscalar quark-antiquark degrees of freedom, also vector and axial-vector mesons, as well as the nucleon and its chiral partner. We extend this model by an additional light scalar meson, a potential four-quark state, and the scalar glueball. We investigate...
The consistent simultaneous interpretation of pions and kaons both as bound states of quark and antiquark and as the (almost) massless boson states related, according to Goldstone’s theorem, to the dynamical (and explicit) breakdown of the chiral symmetries of QCD still represents a major challenge. Applying inversion to sufficiently simplified versions of the homogeneous Bethe–Salpeter...
The spectra of charged and neutral rho and pi-mesons in uniform homogeneous magnetic field (MF) are discussed in the framework of the path integral formalism and vacuum correlator method. The spectra of all 12 spin-isospin s-wave meson states were obtained analytically using the Hamiltonian for quarks with confinement potential in strong magnetic field. The states have 3 different types of...
The extended Linear Sigma Model (eLSM) is an effective hadronic model based on the linear realization of chiral symmetry
$U(N_f)_L \times U(N_f)_R$, with (pseudo-)scalar and (axial-)vector mesons as degrees of freedom. We study the
low-energy limit of the eLSM for $N_f=3$ by integrating out all fields except for the (pseudo-)Nambu-Goldstone bosons of
chiral symmetry breaking. After keeping...
In the potential model frame work, we study the S-wave molecular like structure of the di-baronic systems which consist baryon-baryon or baryon-antibaryon as a constituents. The mass spectra of the $\Sigma_{c}-\Sigma_{c}$ and $\Sigma_{c}-\overline{\Sigma_{c}}$ are predicted. By taking the deuteron as an approximation for our model calculation, the S-wave mass spectra of the molecular...
The electric ($\alpha_{\text{E1}}$) and magnetic ($\beta_{\text{M1}}$) scalar polarizabilities are fundamental properties related to the internal structure of the nucleon. They play a crucial role not only in our understanding of the nucleon, but also in other areas such as atomic physics. In the past, the values of $\alpha_{\text{E}1}$ and $\beta_{\text{M}1}$ were determined from the...
Using Polyakov loop correlators, we calculate the quark potential and energy density profile in pure SU(3) Yang-Mills theory. We investigate the limiting case where the string in baryonic quark configuration approaches the behavior of mesonic strings. We compare the potential and the energy density width profile of diquark-quark and mesonic strings. For isosceles triangular quark...
We continue previous studies of O(N) sigma models whose symmetry suffers of a spontaneous breaking down to O(N-1). We also consider soft explicit breaking terms, first, through an ad hoc variation of the potential and, in a second step, via one-loop corrections to the effective potential. These models are of a high interest for beyond Standard Model extensions (the minimally composite Higgs...
The $J/\psi\to \gamma\eta_{c}$ branching fraction was first measured in $1986$ by the Crystal Ball Collaboration in the inclusive photon spectrum and the value ${\cal B}(J/\psi\to \gamma\eta_{c}\to \gamma X)=(1.27\pm0.36)\%$ was obtained. There are many theoretical predictions for this decay rate, based on potential models, QCD sum rules, nonrelativistic EFTs and lattice QCD, but as a rule...
The coherent inelastic processes of the type $a \rightarrow b$, which may take place in the interaction of hadrons and $\gamma$ quanta with nuclei at very high energies (the nucleus remains the same), are theoretically investigated. For taking into account the influence of matter inside the nucleus, the optical model based on the concept of
refraction index is applied. Analytical formulas for...
We study the decays of two nonets of excited vector mesons which predominantly correspond to $n \hspace{0.15cm} ^{2s+1}L_J = 2 ^{3}S_{1}$ (radially excited vector mesons) and $n \hspace{0.15cm}^{2s+1}L_J = 1 ^{3}D_{1}$ (angular-momentum excited vector mesons). By using a quantum field theoretical approach we evoluate the decay widths of these mesons into two pseudoscalar mesons and into...
Since 2010, candidates for the highly excited states of charmed mesons have been successively observed by the BABAR and LHCb collaborations. Although several theoretical studies have been done, spectroscopic assignments for these states still remain to be completely elucidated.
In this work, following our previous work [1], we study extensively the pionic decays of the radial and highly...
Spin correlations for the $\Lambda\Lambda$ and
$\Lambda\bar{\Lambda}$ pairs, produced in relativistic heavy-ion collisions, and related angular correlations at the joint registration of space-parity nonconserving hadronic decays
of two hyperons are theoretically analyzed. These correlations give important information about the character and mechanism of multiple processes, and the advantage of...
We measure the inclusive production cross sections of hyperons and
charmed baryons from e+e- annihilation using a 800 fb-1 data sample
taken near the Υ(4S) resonance with the Belle detector at the KEKB
asymmetric-energy e+e- collider. The feed-down contributions from
heavy particles are subtracted using our data, and the direct
production cross sections are compared for the first time. The...
A new alternate chi_c0(2P) charmonium state, X*(3860), has been observed
with a significance of 6.5sigma using full amplitude analysis of the
process e+e- -> J/psi D Dbar. We also perform search for
exotic states such as hidden-strangeness penta-quark.
All the results presented here exploits the full data set of Belle.
In analogy to the QED, we analyze the polarizations of gluon and clarify the role of colours within gluons. The effect of polarizations is associated with the spin angular momentum of gluon. Consequently we point out the dependence between colour field and angular-momentum, which can give us an explanation why we cannot confirm the total angular momentum of a high-energy scattering system....
We have analyzed the $\gamma p \rightarrow p \pi^0 \eta$ process with a particular focus on the role of the triangle singularity which appears in the decay of the $\Delta(1700)$ into $\eta \Delta(1232)$,
where the $\Delta(1232)$ goes into $p$ emitting a $\pi^0$, while the $N(1535)$ is formed from the $\eta p$ interaction.
In addition to the triangle diagram, we take account of the tree level...
How much information is added to the Review of Particle
Physics when a new decay branching ratio of a hadron is measured and
reported? This is quantifiable by Shannon's information entropy. It may
be used at two levels, the distribution of decay-channel probabilities,
and the distribution of individual quantum-state probabilities
(integrating the later provides the former). We illustrate...
We introduce a non-relativistic framework to study the spectroscopy of hadronic bound states composed of four charm quarks in the diquark-antidiquark picture. By numerically solving the Schr\"{o}dinger equation with two different Cornell-inspired potentials in a similar way of heavy quarkonium models of mesons, we factorize the 4-body problem into three 2-body systems: first the diquark and...
Pion production in NN collisions is one of the sources of information on the NN
interaction and on the contribution of nucleon resonances. In particular, two-pion production in the few energy range, carries information both on $\pi\pi$ dynamics and on single and double baryon excitation.
The High Acceptance Di-Electron Spectrometer (HADES) [1] installed at GSI Helmholtz-Zentrum für...
In this work, we study the properties of the light baryons employing a constituent quark model in the hypercentral approach. The model considers through the interacting potential one-gluon exchange, Goldstone boson exchange and confinement, aspects of underlying theory, quantum chromodynamics. We introduce three different potential models and solve Schrodinger equation of the baryonic system...
In this work a continuation of an analysis of fine structure effects in nuclear
data is combined with the analysis of particle mass data.
The material used in the work is based on nuclear data compilations collected
in PNPI and data from the Compilations PDG-2016 and the evaluation CODATA.
These data provide a base for the combined analysis of all existing information
for suggested by...
By breaking the initial SU(N) symmetry, we derive the Lagrangian[1] governing the dynamics of the massive scalar particles, which can be treated as the octet of the pseudoscalar mesons. The contribution of both the quark-gluon interaction and self-interaction gluon fields into the masses of the octet of particles is considered. Provided that the hadronization of the confinement matter...
Even though the mechanism is still under discussion, the intrinsic heavy quark mechanism is a rigorous prediction of Quantum Chromodynamics.
Assuming this mechanism to exist, in our talk we discuss how we can naturally explain one of the most intriguing and surprising results in modern baryonic physics, namely the production properties of the double charmed baryons measured by the SELEX...
Using the analogy with the problem of ionization and
excitation of atoms at the propagation of relativistic charged particles through matter, the process of Coulomb dissociation of weakly bound relativistic nuclei and hypernuclei is theoretically investigated in the framework of the two-cluster deuteron-like model. Explicit expressions for the total cross-section of Coulomb disintegration of...
We study the ρB∗B¯∗ three-body system solving the Faddeev equations in the fixed center approximation. We assume the B∗B¯∗ system forming a cluster, and in terms of the two-body ρB∗ unitarized scattering amplitudes in the local Hidden Gauge approach we find a new I(J^PC)=1(3^−−) state. The mass of the new state corresponds to a two particle invariant mass of the ρB∗ system close to the...
During last decade properties of the tetraquark states, which may play an essential role in understanding of hadron dynamics, are among widely discussed problems in the literature. In this work we investigate the thermal features of the state X(3872) with the quantum numbers JPC = 1++. We consider it as a diquark-antidiquark bound state and use QCD sum rule method to explore the nature of...
Themal shifts and fluctuations at finite temperature below the deconfinement crossover from hadronic matter to the quark-gluon plasma provide a viable way to look for missing states with given quantum number in the hadronic spectrum. We study a realization of the hadron resonance gas (HRG) model in the light quark (uds) flavour sector of QCD to study the fluctuations of baryon number, charge...
We report on a recent study of the Bsπ and BK¯ interactions in finite volume [1]. We show the discrete energy levels in two scenarios whether the coupled channel interactions are either strong enough to dynamically generate the X(5568) or too weak to produce it. Supplemented by the state of the art lattice QCD simulations, our study supports the picture that the interactions are weak and the...
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...
We review the status of searches and measurements of exotic hadron states at ATLAS. Among them: the search for the beauty partner of $X(3872)$ charmonium state, the measurement of differential cross-section of the prompt and non-prompt production of $X(3872)$ in the $J/\psi \pi \pi$ final states, the search for the structure in the $B_s \pi$ invariant mass, reported by D0 experiment, search...
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...
In this talk I will present preliminary results on π+, π- and π0 multiplicity ratios measured as a function of multiple kinematical variables in semi-inclusive DIS on three nuclei (C, Fe, Pb) normalized to deuterium . The series of measurements presented here were performed at Jefferson Lab with 5.014 GeV electron beam incident on a double-target system in which liquid deuterium and one of...
Using the Fixed Center Approximation to Faddeev equations we have investigated the $DKK$ and $DK\bar{K}$ three-body systems, with the input of two-body interactions obtained from the chiral unitary approach, and considering that the $D^*_{s0}(2317)$, generated from the $DK$ interaction, acts as the heavy cluster. For the $DK\bar{K}$ system we have found evidence of a state with...
In this work, we investigate the ground states and their radial excitations which couple to scalar, axial vector and tensor, molecular and diquark-antidiquark currents via QCD sum rules. In operator product expansion, we considered quark, gluon and mixed condansates up to dimension eight. For the ground states coupling to these currents, we estimated degenerate masses within 10 MeV...
Introduced in the mid 90’s, Generalized Parton Distributions (GPDs) are now a key element in the study of the nucleon internal structure. Indeed, GPDs encapsulate both spatial and momentum distributions of partons inside a nucleon, and through the Ji sum rule, they also allow to derive the total orbital angular momentum of quarks.
GPDs are experimentally accessible through Deeply Virtual...
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...
Light neutral meson decays provide a unique laboratory to probe fundamental symmetries. A comprehensive Primakoff experimental program at Jefferson Laboratory (JLab) is aimed at gathering high precision measurements on the two-photon decay widths and the transition form factors at low four-momentum transfer squares of $\pi^0$, $\eta$ and $\eta^{\prime}$ via the Primakoff effect. Completed...
An important goal of the future PANDA Experiment at FAIR (Darmstadt, Germany) is the investigation of the proton structure. Electromagnetic form factors parameterize the electric and magnetic structure of protons. In the time-like region electromagnetic proton form factors can be accessed experimentally through the annihilation processes $p\bar{p}\rightarrow l^+l^−$ (l = e, $\mu$), assuming...
We revisit the treatment of radiative decay processes of light-quark qqbar mesons to a pion in the covariant oscillator quark model. Since the pion has an exceptionally light mass compared with other ground-state hadrons, we have difficulty in dealing with pions within the constituent quark model, including the covariant oscillator quark model. The pion is a pseudo-Nambu-Goldstone boson...
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 measured properties of the $X(3915)$ and $X(3930)$ make difficult their theoretical
description. These charmonium resonances, firstly detected by the
Belle and BaBar Collaborations in $\gamma\gamma$ fusion process, were measured
in different final channels: the $X(3915)$ was discovered in the $\omega
J/\psi$ [1, 2] invariant mass distribution whereas the $X(3930)$ was seen in the...
In this talk we will study the implications on heavy hadron molecules (containing one constituent heavy quark) of heavy quark spin-flavor and chiral symmetries (together with unitarity). We start by studing the $D\pi$, $D\eta$ and $D_s \bar{K}$ scattering with $(I,J^P) = (1/2,0^+)$ quantum numbers. In this sector there appears the so far only known charmed non-strange scalar meson, namely...
The NA48/2 experiment at CERN collected a very large sample of charged kaon decays into multiple final states.
This data allow measurements related to QCD and Chiral Perturbation Theory, and the an updated measurement of |VUS|.
In particular, we collected about 1500 events of the very rare decay K+- —>mu+- nu e+ e- over almost negligible background in the region with m(e+e-) above 140 MeV,...
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 Bethe–Salpeter equation. The conventional meson spectrum has been estimated with reasonable accuracy in a...
The observation of the unexpected $XYZ$ resonances has challenged the ordinary heavy quarkonium framework, and their microscopic nature remains an unsettled topic.
We review the status of the multiquark phenomenology, and show how the large prompt production cross-section of the $X(3872)$, compared with the light nuclei production data, disfavors loosely-bound molecules, and calls for other...
Hadronic B decays without a charm quark constitute a powerful probe to search for physics beyond the standard model as well as provide constraints of CP-violation parameters. We report the final measurements from Belle of the branching fraction and CP asymmetry for the decays B0→π0π0, B±→K+K−π± and preliminary results for B→KS0KS0h+(h=K,π) and B±→π+π−π±. All investigations employ the full data...
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 mechanisms behind baryonic decays of heavy flavoured particles remain mysterious and challenging to describe theoretically. Interesting properties of such decays include the suppression of branching fractions to two-body final states and threshold enhancements in higher multiplicity decays. The large data sample accumulated by the LHCb experiment between 2011 and 2016 enables a variety of...
We present a recent lattice QCD investigation of charm tetraquarks. After describing some of our new methodology, we demonstrate its use in calculations with unphysically heavy light quarks such that the pion mass is 391 MeV. Spectra in the doubly charmed and hidden charmed sector will be shown including those which are of relevance to the experimentally observed charged $Z_c$ states.
The evaluation of partonic distributions presents a challenge for QCD, and in particular for its lattice realization. Recently, objects called quasidistributions (which become standard distributions in a limit of the longitudinal momentum of the target hadron going to infinity) have been proposed, but their features are not fully comprehended. We present a dynamical evaluation of the quark...
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 $B$ mesons are the lightest mesons which can decay to various final states containing different baryons. Up to now, the discrepancy between the inclusive branching fraction of all $B$ meson decay modes with at least a couple of baryons in the final state, measured by ARGUS to be $(6.8 +- 0.6)\%$ , and the sum of exclusive baryonic channels, averaged on neutral and positive $B$ mesons at...
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...
Strange and charmed hyperons are an ideal tool to study the strong
interaction in the transition region between non-perturbative and perturbative QCD regime.
In this presentation prospects for antihyperon-hyperon
studies in elementary annihilation reactions are reviewed.
Special emphasis is put on recent results from BESIII and prospect for the
future PANDA experiment at FAIR.
After the discovery of X(3872) many new and unexplained X Y Z states have been discovered experimentally in recent times [1]. It has helped in our faith towards the existence of multi quark states. Most of these unknown states consist of hidden heavy quark anti quark pair with combinations of quark/antiquark in the lighter sector (cq$\bar{c}$ $\bar{q}$or bq$\bar{b}$ $\bar{q}$ where q ϵ u, d,...
We study the relationship between the D∗s0(2317)+ resonance and the decay of the Bc meson into J/ψDK. In this process, the Bc meson decays first into J/ψ and the quark pair cs¯, and then the quark pair hadronizes into DK or D_sη components, which undergo final state interaction. This final state interaction, generating the D∗s0(2317)+ resonance, is described by the chiral unitary approach....
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...
Experimental results on three-body charmless non-leptonic B decays have shown a considerable amount of direct CP asymmetry localized in specific regions of the Dalitz plot. In the low hadron-hadron mass region, we recently showed that the final state interactions (FSI) play a very important role, providing through $\pi\pi\to KK$ rescattering the strong phase difference needed for direct CP...
The forward acceptance of LHCb, 2.0 < y < 5.0, provides a complementary reach to the general purpose detectors at the LHC. LHCb measurements of the inelastic cross-section and related results will be presented, as well as a comparison to Run 1 results.
The evidence for an unexpected narrow Bs pi structure claimed by the D0 Collaboration and named X(5568) has triggered its search in other hadron collider experiments including CMS. Its interest resides in its possible interpretation as a compact hadronic state composed of four different quark flavours (udsb). The CMS search is performed using an integrated luminosity of 19.7fb^-1 of pp...
We present recent results on hadron production in e+e- annihilation including double charmonium production, gamma-gamma fusion, hadron production with initial state radiation and from decays of B-mesons. We discuss the status of both standard and exotics hadron searches. Our review covers new results from Belle, BaBar, BESIII Collaborations and discussion of perspectives for future experiments...
We elaborate on the compositeness relation for poles in the two-body scattering amplitudes, and discuss different methods to calculate the compositeness of a resonance and bound state. We study in detail the case of validity of the effective-range expansion for near-threshold poles and its limitations, providing then a more general parameterization from S-matrix theory. The application of...
A continuum approach to the pion, kaon and pseudoscalar $ss$ bound-state problems is used to reveal their electromagnetic structures. For these systems, when used with parton disbribution amplitudes appropriate to the scale of experiment,
Standard Model hard-scattering formulae are accurate to within 25 % at medium momentum transfers. The large Q^2 evolution is accurately described by the hard...
This session, open to the non-expert public, introduces physical and clinical aspects of hadrontherapy, as an example on how basic investigation may produce applied results.
In contrast with conventional X-ray radiotherapy, where energy is continuously deposited before reaching the tumor, in hadrontherapy the majority of this energy is deposited in single point, thus avoiding damage in the...
In addition to the normal hadron resonances, kinematical singularities such as the two-body threshold cusps and triangle singularities can also produce peaks. Such structures may mimic resonances, and lead to ambiguities in interpretations. In this talk, I will discuss various aspects of kinematical singularities, including how to distinguish them from resonances and how to make use of them.
The search mesons composed of light quarks with combinations of angular momentum (J), parity (P), and charge conjugation (C) that cannot be formed by a quark-antiquark pair has been a topic of experimental interest for several decades. While QCD does not seem to forbid the formation of exotic mesons, the evidence supporting their existence in nature is sparse. If such mesons do exist in...
One of the most challenging subjects in nuclear and hadron physics today is to clarify high density baryonic matter in the core of neutron stars. Most of nuclear theories have been constructed referring to experimental data of nuclei with a density equal or less than $\rho_0$ and cannot be reliably extrapolated to the density larger than $\rho_0$. In particular, considering the Fermi energy of...
One of the remaining challenges within the standard model is to gain a good
understanding of QCD in the non-perturbative regime. A key step towards this
aim is baryon spectroscopy, investigating the spectrum and the properties of
baryon resonances. To gain access to resonances with small $\pi N$ partial
width, experiments with electromagnetic probes provide essential information.
Partial wave...
LHCb continues to expand its world-leading sample of charmed hadrons collected during LHC’s Run 1 (2010-2012) and Run 2 (2015- present). This sample is yielding some of the most stringent tests of the Standard Model understanding of charm physics. This includes sensitive searches for direct and indirect CP violation in charm interactions and for charm decays that are heavily suppressed or...
The A2 Collaboration at the Mainz Microtron MAMI measures photon absorption cross sections using circularly and linearly polarized 'Bremsstrahlung' photons up to an energy of ~1.5GeV and a polarized Frozen Spin Target. We use a 4 $\pi$ detection system with the 'Crystal Ball' as central part.
One important experimental topic is the investigation of the nucleons excitation spectrum. ...
Generalized Parton Distributions (GPDs) provide a comprehensive description of the partonic structure of the nucleon and contain a wealth of new information. In particular, they provide a description of the nucleon as an extended object, referred to as 3-dimensional nucleon tomography, and give an access to the orbital angular momentum of quarks.
In my talk I will focus on the GPD...
We describe studies of heavy states with charm and beauty in
the Belle experiment. Particular attention is drawn to production
and decays of heavy quarkonia for which the interpretation is
not yet clear. Also discussed is a search for a pentaquark.
New measurements of the helicity dependence of the total inclusive photo-absorption cross section and of the partial cross sections for several reaction channels on the proton and on the neutron were carried out at the tagged photon beam facility of the MAMI accelerator (Mainz) by the A2 experiment in the energy region 200 < E$_\gamma$ < 1500 MeV.
These new, high-quality doubly-polarized...
The exploration of hadron 3-dimensional structure in high-energy collisions can help us better understand QCD, and how the properties of hadrons arise from the dynamics of their internal constituents.
In this talk I will address the quarkonium production in lepton-hadron and hadron-hadron collisions, which proves to be a very useful tool to unravel the gluon content of hadrons.
By applying the...
We study the $D^+_s \to \pi^+ \pi^+ \pi^-$ and $D^+_s \to \pi^+ K^+ K^-$ decays adopting a mechanism in which the $D^+_s$ decays weakly into a $\pi^+$ and a $q\bar{q}$ component, which hadronizes into two pseudoscalar mesons. The final state interactions between these two pseudoscalar mesons is taken into account by using a chiral unitary approach in coupled channels, which gives rise to the...
The talk will include the summary of COMPASS measurements of gluon polarisation in the nucleon and the final results concerning the spin dependent structure function g1. In order to improve flavour-by-flavour knowledge of the spin structure of the nucleon the so called semi-inclusive measurements of hadron asymmetries were performed. To fully profit from these measurements a more precise...
Several new findings in the four, five and six quark systems reheat the interest in the field of multiquark states (beyond trivial $q\bar q$ and qqq). A lot of progress has recently been made in the 6q sector, on both the theoretical and experimental side. A resonance like structure observed in double-pionic fusion to the deuteron, at M=2.38 GeV with $\Gamma=70 MeV$ and $I(J^P )=0(3^+)$ has...
K->pinunu is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN SPS is designed to measure the branching ratio of the K+->pi+nunu decay with 10% precision. NA62 took data in 2015 and 2016 reaching the Standard Model sensitivity. The experiment will be reviewed, and recent results and...
The dibaryon resonance d*(2380) with I(JP) = 0(3+) -- first observed in the
double-pionic fusion to the deuteron [1] -- has meanwhile been detected in all
relevant two-pion production channels in incident neutron-proton collisions
[2]. In addition, its resonance pole has been revealed in neutron-proton
scattering [3].
Theoretical calculations describe this state either as a compact hexaquark...
The search for non-strange dibaryon bound/resonance states has a long history.
A dibaryon state is of interest, which can be a molecule consisting of
two baryons or a spatially compact hexaquark object. The d*(2380) resonance
observed in the $pn$-collision reactions by the CELESIUS/WASA and WASA-at-COSY [1,2]
collaborations may be attributed to an isoscalar $\Delta\Delta$ quasi-bound...
In recent years, several experiments at the $e^-p$ collider HERA have collected high precision data on the spectrum of leading-baryons carrying a large fraction of the proton's energy. In this paper, we have analyzed recent experimental data on the production of forward proton and neutrons in deep inelastic scattering at HERA in the framework of a perturbative QCD.
We propose a technique based...
We carry out hadron photoproduction experiments at E$\gamma$=1.5-3.0 GeV at SPring-8/LEPS. We took charged pion data on the proton at forward angles for the first time and the data were analyzed recently. The differential cross sections for the $\pi^{-}\Delta^{++}$ and $\pi^{+}\Delta^{0}$ reactions are compared. In the $\pi^{-}\Delta^{++}$ reaction $\bar{u}u$ is produced, while in the...
Recent Lattice QCD predictions for the mass of H-dibaryon pointing to the mass region near $\Lambda\Lambda$ and $\Xi^-p$ thresholds encourage experimental searches. A dedicated experiment (J-PARC E42) has been prepared for hunting the H-dibaryon close to $\Lambda\Lambda$ and $\Xi^-p$ thresholds. The experiment was
designed to measure $\Lambda p\pi^-$, $\Lambda\Lambda$ and ?$\Xi^-p$...
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...
The phenomenon of CP violation has been observed in the K- and B-meson systems, but not yet with any baryonic particle. Charmless decays of beauty baryons are of particular interest in with this respect, as they receive contributions from both tree- (b->u) and loop-level (b->d and b->s) transitions with similar magnitude. We present the most recent measurements of CP violation observables in b...
We report on the first observation of excited hadronic states in the beauty sector, with emphasis on beauty baryons.
Similar techniques are used to search the LHCb data for states observed in other datasets, such as the tetraquark state X(5568) whose evidence was reported by D0.
Furthermore, we discuss the searches for doubly heavy baryons, such as the doubly charmed Xicc and charmed-beauty...
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...
In 2014. BESIII collected a data sample of 567 pb-1 at Ecm = 4.6 GeV, which is just above the Lambda_c+ pair production threshold. By analyzing this data sample, we have measured the absolute branching fractions for many decays of Lambda+c for the first time. These decays include the semileptonic decays of Lambda e+v, Lambda mu+v, the hadronic decays of pKs, pK-pi+, pK-pi+pi0, Lambda pi+,...
$\Omega_{bbb}$ is triply heavy beauty quark baryon which makes the system very interesting. We do not have any experimental observed states for $\Omega_{bbb}$ \cite{olive}; but many lattice calculations \cite{brown, PAD2014} as well as theoretical predictions \cite{vijande2015, kwei2} have been performed for ground and excited states of this baryons. We use Hypercentral Constituent Quark model...
We will report on the status of the search for the eta-mesic nuclei and the studies of the interaction of the eta and eta-prime meson with nucleons. The existence of the eta-mesic nucleus was postulated over twenty nine years ago, however, till now it was not confirmed experimentally. Such system in the form of the eta mesic-helium may be created for example in the deuteron-deuteron or...
The $P_c(4380)$ and $P_c(4450)$ states observed recently by LHCb experiment were proposed to be either $\bar{D} \Sigma_c^*$ or $\bar{D}^* \Sigma_c$ bound states. We analyze the decay behaviors of such two types of hadronic molecules within the effective Lagrangian framework. With branching ratios of ten possible decay channels calculated, it is found that the two types of hadronic molecules...
The real part of the $\eta^\prime$-nucleus potential has been determined at low momenta by analyzing the $\eta^\prime$ kinetic energy distribution and the excitation function in photoproduction of of $\eta^\prime$ mesons off C in coincidence with forward going protons. The forward going protons take over most of the momentum of the incoming photon beam and thus their detection allows the study...
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...
From the perspective that the $\Lambda_c(2595)$ and $\Lambda_c(2625)$ are dynamically generated resonances from the $DN,~D^*N$ interaction and coupled channels, we have evaluated the rates for $\Lambda_b \to \pi^- \Lambda_c(2595)$ and $\Lambda_b \to \pi^- \Lambda_c(2625)$ up to a global unknown factor that allows us to calculate the ratio of rates and compare with experiment, where good...
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...
In this work we calculate the ratios of rates of the $Ξ_b$ nonleptonic and semileptonic decays into the $Ξ_c$(2790) and $Ξ_c$(2815) ($Ξ_c^{*}$) resonances. These resonances are dynamically generated from the pseudoscalar-baryon and vector-baryon interactions, whose mixing is done using the chiral Weinberg-Tomozawa (WT) meson-baryon interaction extended to four flavors. The first part of the...
The nature of chiral symmetry restoration and the identification of its correct pattern in terms of $O(4)$ and $U(1)_A$ restoration are central problems for our present understanding of the QCD phase diagram, which are not fully settled in lattice simulations. We will present a theoretical analysis based on Ward Identities which sheds light on this issue and where partner degeneration is...
Using the Regge-like formula $(M-m_Q)^2=\pi\sigma L$ between hadron mass $M$ and angular momentum $L$ with a heavy quark mass $m_Q$ and a string tension $\sigma$, we analyze heavy-light systems like $D/D_s/B/B_s$ mesons and charmed and bottomed baryons.
Numerical plots are obtained for $D/B$ mesons of experimental data whose slope coefficient becomes nearly equal to 1/2 of that for light...
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...
The BESIII Experiment at the Beijing Electron Positron Collider (BEPC2) has accumulated the world's largest samples of e+e- collisions in the tau-charm region. Using a sample of 106 million psi(3686) decays, the branch fractions of psi(3686) -> gamma chi_c0, gamma chi_c1, gamma chi_c2 are determined to be (9.389 +- 0.014 +- 0.332)%, (9.905 +- 0.011 +- 0.353)%, and (9.621 +- 0.013 +- 0.272)%,...
Investigation of GPDs and TMDs represents the major goal of the COMPASS-II program. Together, GPDs and TMDs provide the most complete description of the partonic structure of the nucleon.
GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular DVCS and DVMP. At COMPASS, these processes are investigated using a 160 GeV high intensity muon beam and a 2.5 m long...
Exotic charmonium-like XYZ states have been targeted by various experiments in the last 15 years,
but their nature still is unknown. Photo-(muo)production, is a new promising instrument to study them.
COMPASS, a fixed target experiment at CERN, analyzed the full set of the data collected with a
muon beam between 2002 and 2011, covering the range from 7 GeV to 19 GeV in the centre-of-mass...
We investigate the decays of the charmed baryons aiming at the systematic understanding of hadron internal structures based on the quark model by paying attention to heavy quark symmetry. We evaluate the decay widths and branching ratio for the pion emission for the known excited Lambca_c baryons. We find an interesting selection rule for the decays depending on their internal structure.
We...
Using more than 900 fb-1 data collected with the Belle detector at
the KEKB asymmetric-energy e+e- collider, we report observation of
excited charmed baryon states. We also provide their mass and width
measurements (with an order of magnitude of improvement). In addition,
direct production cross-section of charmed baryons is also presented.
Electric (E1) and magnetic (M1) dipole transitions have been studied since the early days of hadron spectroscopy because they allow to access heavy quarkonium states which are below open-flavour threshold. Moreover, these reactions are interesting by themselves because they are an important tool to check particular regions of the hadrons' wave function and thus to determine their internal...
We will present an introduction to the physics of exotic charmonium, describing
the most popular configurations proposed for these states: tetraquark and meson molecules. I will then show how these states can be produced in hadronic collisions and in heavy ion collisions, both in central and peripheral reactions. I
will present our latest results on the production cross sections,...
Next-generation nucleon parton density functions (PDFs) with additional transverse momentum dependence (TMD) provide crucial information to understand the role of partonic orbital angular momentum in the nucleon spin. Among them, Sivers function characterizes the distribution of unpolarized quarks with nonzero transverse momentum inside a transversely polarized nucleon. Based on TMD...
The future experiment PANDA@FAIR is a fix-target ppbar machine that will run in the energy range [1.5-15.0] GeV, and it is supposed to reach a peak luminosity of about 2 * 10^31 cm-2 s-1 in the first phase of data taking. This will allow to perform a number of analyses which are suppressed or forbidden at e+e- colliders, especially in the sector of charm- and charmonium physics. To investigate...
LHCb continues to expand its world-leading sample of charmed hadrons collected during LHC’s 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. LHCb’s latest work on the spectroscopy of charmed hadrons is presented.
By means of resonance chiral theory we compute the contribution of spin-2 resonances to the tau -> nu pi pi pi decay. We build a chiral invariant Lagrangian for tensor and axial-vector resonances that implements chiral symmetry (and isospin) in the process. This ensures that the hadronic amplitudes follow the low-energy behaviour prescribed by chiral perturbation theory. Likewise, by imposing...
The search for resonances, both exotic and otherwise, as intermediate states in beauty and charm hadron decays at LHCb has been extremely productive in recent times. We present recent results in the amplitude analysis of these decays. Among others, this includes studies of Lb -> D p pi decays, which allow to constrain the spin/parity of the Lc(2940)+ state for the first time, and evidence for...
Large mass, non-relativistic dynamics, large energy level spacing and clear
experimental signature are unique characteristics of the bottomonium states
that make this sector so rich with a wide range of opportunities for new
studies, ranging from the the spin structure of QCD to the extensions of the SM
Lagrangian, from the non-$q\bar{q}$ states and light quarks dynamics to the
gluon...
We perform calculations for the $\eta_c \to \eta \pi^+ \pi^-$ decay using elements of SU(3) symmetry to see the weight of different trios of pseudoscalars produced in this decay, prior to the final state interaction of the mesons. After that, the interaction of pairs of mesons, leading finally to $\eta \pi^+ \pi^-$, is done using the chiral unitary approach. We evaluate the...
We examine the interaction of $D N$ and $D^* N$ states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where...
In heavy quarkonia, hadronic transitions serve as an enlightened probe for the structure and help to establish the understanding of light quark coupling with a heavy degree of freedom. Moreover, in recent years, hadronic transitions revealed remarkable discoveries to identify the new conventional heavy quarkonia and extracting useful information about the so called “XYZ” exotic states.
In...
We study the weak decay of the $\Lambda_b$ baryon into $J/\Psi \phi \Lambda$ states and the possibility of producing exotic hadrons via final state interaction in $J/\Psi \phi$ and $J/\Psi \Lambda$ channels.
The elementary weak transition at the quark level proceeds via the creation of a $J/\Psi (\bar{c} c)$ meson and an excited sud system with I = 0, which upon hadronization leads...
In a recent experiment performed at the electron accelerator MAMI a systematic study on the ground state binding energy of hyperhydrogen 4LH was performed. The energy was deduced from the spectroscopy of mono-energetic pions from the two-body decays of hyperfragments, which were produced and stopped in a 9Be target. While the ground state binding energy difference of DBL(0+g.s.)...
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...
The forward acceptance of LHCb, 2.0 < y < 5.0, provides a complementary reach to the general purpose detectors at the LHC. LHCb measurements of Bose-Einstein correlations in particle production will be presented.
Spectroscopic study of Lambda hypernuclei has started at Jefferson Lab in 2000, the last year of the 20th century.
There were many experimental difficulties such as small production cross section, huge electron background and so on.
We, finally, established the Lambda hypernuclear spectroscopy with electron beam by introducing novel experimental techniques and efforts of more than a...
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...
Recent high-precision measurements in light hypernuclei using magnetic spectrometers have changed our knowledge of the $\Lambda N$ interaction. Accessible observables are $\Lambda$ binding energies, excitation spectra (if particle-bound excited states exist), spins, lifetime and decay branching ratios. Substantial differences between emulsion studies and recent magnetic spectrometer...
Latest results on study of processes of e+e− annihilation into exclusive hadronic states with $\sqrt{s}$ < 2 GeV obtained in the SND experiment at the VEPP-2M and VEPP-2000 colliders are presented. In particular, we announce results of the precise measurements of the $e^{+}e^{-} \to \gamma\pi^{0}$ and $e^{+}e^{-} \to K^{+}K^{-}$ cross sections, the first measurements of the $e^{+}e^{-} \to...
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...
In Universe there are many varieties of matter created by the strong interaction, such as hadrons,
nuclei and the very high density quark matter which might be formed inside a neutron star. Because
those particles and matter are generated by the strong interaction, the theory of strong interaction,
i.e. the Quantum Chromo dynamics(QCD), will give answers how those states are forming...
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...
The top quark is the heaviest of all discovered particles so far. Knowing its mass precisely is of utmost importance to test the validity of the Standard Model. The most precise measurements performed at Hadron Colliders determine the MC top quark mass parameter. Relating this parameter to a field-theoretically well defined mass is necessary if those determinations are to be used as input to...
In the past years, distribution functions depending on the transverse momentum of partons in the nucleon (TMDs) have been intensely studied in spin physics. The TMDs represent one approach to disentangle the multi-dimensional structure of the nucleon. Correlations of the transverse spin of quarks with their transverse momentum can be observed by measuring spin azimuthal asymmetries. Recent...
Hadrons emerge as strongly interacting, relativistic bound states of quarks and gluons in Quantum Chromodynamics (QCD), the theory of the strong force. They are not static but have complex dynamical internal structure, which are only beginning to be revealed in modern experiments. Since no modern detector can see quarks and gluons in isolation, it is an unprecedented intellectual challenge to...
The Electron-Ion Collider (EIC) is envisioned as the next generation facility for exploring the strong interaction (Quantum ChromoDynamics, QCD). Our understanding of QCD has advanced enormously in the past decades. Both experimentally and theoretically, the perturbative regime in QCD has been explored and understood with precision. At the same time, lattice QCD calculations have begun to...
