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...
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...
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...
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 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.
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...
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
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....
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...
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...
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...
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...
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...
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...
Extensions of the NJL model which go beyond the original 4-quark interaction, which drives the dynamical mass generation, have proven to be quite successful in describing low energy hadronic phenomenology. The inclusion of 8-quark interaction terms solved a metastability problem of the effective potential
introduced by the inclusion of the 6-quark 't Hooft determinant term in the 3-flavor...
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...
The BABAR Collaboration has an intensive program ย studying hadronic cross sections in low-energy ย $e^+e^-$ 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. ย
These improvements are necessary for...
The KLOE experiment has collected 2.5 fb$^{-1}$ at the $e^+e^-$ collider DAPHNE. The upgraded detector KLOE-2 has already collected 3.5 fb$^{-1}$ with a new beam crossing scheme, allowing for a reduced beam size and increased luminosity. Analysis of KLOE data is still in progress, providing new important results in the light meson sector. VPgamma* transitions have been studied using the...
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...
We will report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment used the 6 GeV electron beam from the CEBAF accelerator at
Jefferson Lab incident on a pressurized $^4$He gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron was detected by...
In this talk I will present preliminary results on ฯ+, ฯ- and ฯ0 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...
Introduced in the mid 90โs, 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...
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 $p\bar{p}\rightarrow l^+l^โ$ (l = e, $\mu$), assuming...
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+- โ>mu+- nu e+ e- over almost negligible background in the region with m(e+e-) above 140 MeV,...
Generalized Parton Distribution (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. GPDs can be accessed experimentally with hard exclusive processes such as Deeply Virtual Compton Scattering (DVCS) and deeply virtual pi0 production. Two experiments were performed in the Hall A of Jefferson Lab to measure the unpolarized...
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...
We propose a new method for calculating the dependences of the decay constants of heavy-light mesons on the light-quark mass m based on QCD sum rules at infinitely large Borel mass parameter. For an appropriate choice of the correlation functions, all condensate contributions vanish and the m-dependence of the decay constants is shown to be mainly determined by the known analytic m-dependence...
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.
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.
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...
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...
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...
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...
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...
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...
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...
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...
A determination of the heavy quark masses from combinations of QCD sum rules of the moments of the vector current correlator calculated in perturbative QCD are presented. Only experimental data for the resonance below the continuum threshold are needed in our approach, while the continuum contribution is determined by requiring self-consistency between various sum rules and the zeroth moment....
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.
Latest results on study of processes of e+eโ 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 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...
