scholarly journals Dynamical Properties of Baryons

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1480
Author(s):  
Egle Tomasi-Gustafsson ◽  
Andrea Bianconi ◽  
Simone Pacetti
Keyword(s):  
Virtual Photon ◽  
Form Factors ◽  
Dynamical Structure ◽  
Kinematical Region ◽  
Baryonic Matter ◽  
Unique Role ◽  
Elementary Reactions ◽  
Electron Accelerators ◽  
Electron Positron ◽  
Periodical Structure

The internal structure of composite particles is conveniently described in terms of form factors (FFs)—these are experimentally accessible in annihilation and scattering of elementary reactions, and are theoretically calculable by all models that describe the properties of particles. FFs depend only on one kinematical variable, q2. This is the four-momentum transferred by the virtual photon that carries the interaction. Important developments in accelerator and detector techniques have brought impressive advances, both by extending the kinematical region and by reaching a higher precision. A critical review on the underlying methods and findings in polarized and unpolarized experiments is presented. The unique role played by polarization in determining the ratio of electric to magnetic form factors in the space-like region, and the extraction of individual form factors in the whole kinematical region, are described. Recent results at electron accelerators and electron–positron colliders confirm the existence of periodical structure in the annihilation cross section. We suggest a global framework which describes the dynamical structure of charge distribution in baryons, in order to build a coherent view of the creation and annihilation of baryonic matter.

scholarly journals D → π and D → K semileptonic form factors with Nf = 2 + 1 + 1 twisted mass fermions

2018 ◽  
Vol 175 ◽  
pp. 13026
Author(s):  
Vittorio Lubicz ◽  
Lorenzo Riggio ◽  
Giorgio Salerno ◽  
Silvano Simula ◽  
Cecilia Tarantino
Keyword(s):  
Pion Mass ◽  
Form Factors ◽  
Kinematical Region ◽  
Matrix Elements ◽  
Scalar Form ◽  
Mass Collaboration ◽  
Twisted Mass ◽  
The Matrix ◽  
Additional Form

We present a lattice determination of the vector and scalar form factors of the D → π(K)lv semileptonic decays, which are relevant for the extraction of the CKM matrix elements |Vcd| and |Vcs| from experimental data. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 + 1 +1 flavors of dynamical quarks. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. The matrix elements of both vector and scalar currents are determined for a plenty of kinematical conditions in which parent and child mesons are either moving or at rest. Lorentz symmetry breaking due to hypercubic effects is clearly observed in the data and included in the decomposition of the current matrix elements in terms of additional form factors. After the extrapolations to the physical pion mass and to the continuum limit the vector and scalar form factors are determined in the whole kinematical region from q2 = 0 up to [see formula in PDF] accessible in the experiments, obtaining a good overall agreement with experiments, except in the region at high values of q2 where some deviations are visible.

Impact of scalar mesons on the rare B-decays

2015 ◽  
Vol 39 ◽  
pp. 1560086
Author(s):  
Aidos Issadykov ◽  
Mikhail A. Ivanov ◽  
Sayabek K. Sakhiyev
Keyword(s):  
Angular Distribution ◽  
Quark Model ◽  
Scalar Meson ◽  
Form Factors ◽  
Kinematical Region ◽  
Transition Form ◽  
B Decays ◽  
Straightforward Calculation ◽  
Scalar Mesons ◽  
Covariant Quark Model

In the wake of exploring uncertainty in the full angular distribution of the [Formula: see text] caused by the presence of the intermediate scalar [Formula: see text] meson, we perform the straightforward calculation of the [Formula: see text] (S is a scalar meson) transition form factors in the full kinematical region within the covariant quark model. We restrict ourselves by the scalar mesons below 1 GeV: [Formula: see text]. As an application of the obtained results we calculate the widths of the semileptonic and rare decays [Formula: see text], [Formula: see text] and [Formula: see text]. We compare our results with those obtained in other approaches.

scholarly journals BFKL PHYSICS IN JET PRODUCTION AT e+e- COLLIDERS

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 209-211
Author(s):  
LYNNE H. ORR ◽  
W. J. STIRLING
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Cross Section ◽  
Virtual Photon ◽  
Bfkl Equation ◽  
Photon Scattering ◽  
Kinematic Constraints ◽  
Large Rapidity ◽  
Electron Positron ◽  
Electron Positron Pair

Virtual photon scattering in e+e- collisions can result with the electron-positron pair at large rapidity separation with hadronic activity in between. The BFKL equation resums large logarithms that dominate the cross section for this process. We report here on a Monte Carlo method for solving the BFKL equation that allows kinematic constraints to be taken into account and show results for e+e- collisions.

scholarly journals A systematic $1/c$-expansion of form factor sums for dynamical correlations in the Lieb-Liniger model

2020 ◽  
Vol 9 (6) ◽  
Author(s):  
Etienne Granet ◽  
Fabian Essler
Keyword(s):  
Luttinger Liquid ◽  
Form Factors ◽  
Dynamical Structure ◽  
Dynamical Structure Factor ◽  
Space And Time ◽  
Liquid Theory ◽  
Generalized Hydrodynamics ◽  
Quantum Quenches ◽  
Temperature Equilibrium ◽  
Arbitrary Energy

We introduce a framework for calculating dynamical correlations in the Lieb-Liniger model in arbitrary energy eigenstates and for all space and time, that combines a Lehmann representation with a 1/c1/c expansion. The n^\mathrm{th}nth term of the expansion is of order 1/c^n1/cn and takes into account all \lfloor \tfrac{n}{2}\rfloor+1⌊n2⌋+1 particle-hole excitations over the averaging eigenstate. Importantly, in contrast to a "bare" 1/c1/c expansion it is uniform in space and time. The framework is based on a method for taking the thermodynamic limit of sums of form factors that exhibit non integrable singularities. We expect our framework to be applicable to any local operator. We determine the first three terms of this expansion and obtain an explicit expression for the density-density dynamical correlations and the dynamical structure factor at order 1/c^21/c2. We apply these to finite-temperature equilibrium states and non-equilibrium steady states after quantum quenches. We recover predictions of (nonlinear) Luttinger liquid theory and generalized hydrodynamics in the appropriate limits, and are able to compute sub-leading corrections to these.

EXCLUSIVE HADRON PRODUCTION IN TWO-PHOTON REACTIONS

1986 ◽  
Vol 01 (03) ◽  
pp. 545-668 ◽  
Author(s):  
M. POPPE
Keyword(s):  
Pair Production ◽  
Form Factors ◽  
Hadron Production ◽  
Model Calculations ◽  
New Model ◽  
Know How ◽  
Two Photon ◽  
Electron Positron ◽  
Parameters Selection ◽  
Free Parameters

This paper summarizes experimental results on exclusive hadron production in two-photon collisions at electron-positron storage rings and attempts some interpretation. Experimental know-how is described and new suggestions are made for future analyses. New model calculations on resonance form factors and pair production amplitudes are presented. The two-photon vertex is decomposed such that experiments can be parameterized with the minimal number of free parameters. Selection rules for off-shell photon collisions are given in addition to Yang’s theorems. [Formula: see text]

scholarly journals Time-like Proton Form Factors with Initial State Radiation Technique

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 91
Author(s):  
Dexu Lin ◽  
Alaa Dbeyssi ◽  
Frank Maas
Keyword(s):  
Experimental Studies ◽  
Form Factors ◽  
Initial State Radiation ◽  
Initial State ◽  
Radiation Process ◽  
Electron Positron ◽  
Born Cross Section ◽  
State Radiation ◽  
Radiation Technique ◽  
Proton Form Factors

Electromagnetic form factors are fundamental quantities describing the internal structure of hadrons. They can be measured with scattering processes in the space-like region and annihilation processes in the time-like region. The two regions are connected by crossing symmetry. The measurements of the proton electromagnetic form factors in the time-like region using the initial state radiation technique are reviewed. Recent experimental studies have shown that initial state radiation processes at high luminosity electron-positron colliders can be effectively used to probe the electromagnetic structure of hadrons. The BABAR experiment at the B-factory PEP-II in Stanford and the BESIII experiment at BEPCII (an electron positron collider in the τ-charm mass region) in Beijing have measured the time-like form factors of the proton using the initial state radiation process e+e−→pp¯γ. The two kinematical regions where the photon is emitted from the initial state at small and large polar angles have been investigated. In the first case, the photon is in the region not covered by the detector acceptance and is not detected. The Born cross section and the proton effective form factor have been measured over a wide and continuous range of the the momentum transfer squared q2 from the threshold up to 42 (GeV/c)2. The ratio of electric and magnetic form factors of the proton has been also determined. In this report, the theoretical aspect and the experimental studies of the initial state radiation process e+e−→pp¯γ are described. The measurements of the Born cross section and the proton form factors obtained in these analyses near the threshold region and in the relatively large q2 region are examined. The experimental results are compared to the predictions from theory and models. Their impact on our understanding of the nucleon structure is discussed.

scholarly journals Parity-violating electron scattering

2020 ◽  
Vol 15 ◽  
pp. 2
Author(s):  
S. Kowalski
Keyword(s):  
Standard Model ◽  
Electron Scattering ◽  
High Intensity ◽  
Form Factors ◽  
Beyond The Standard Model ◽  
Weak Charge ◽  
Strange Form Factors ◽  
Electron Accelerators ◽  
New Information ◽  
The Standard Model

Parity violating electron scattering has been a very useful tool for probing the structure of neutral currents and providing detailed information on electroweak form factors. A pioneering SLAC measurement in the mid-70’s provided an important early test of the Standard Model. Modern electron accelerators provide high intensity (>100 μA), CW beams with polarizations as high as 85%. Experiments such as SAMPLE, A4, HAPPEX and G0 have exploited these capabilities and obtained new information on electroweak strange form factors in the Q2 range of 0.1-1.0 GeV2. That activity continues. Other experiments are designed to provide stringent tests of the Standard Model. E-158 at SLAC recently measured the weak charge of the electron. Qweak is a challenging new experiment at JLAB which is designed to measure the weak charge of the proton. This will probe for physics beyond the Standard Model corresponding to energy scales of more than 5TeV.

scholarly journals Production Mechanism of the Charmed Baryon Λc+

Symmetry ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 5
Author(s):  
Weiping Wang ◽  
Xiaorong Zhou ◽  
Rinaldo Baldini Ferroli ◽  
Guangshun Huang
Keyword(s):  
Cross Section ◽  
Production Cross ◽  
Center Of Mass ◽  
Polar Angle ◽  
Form Factors ◽  
Electromagnetic Form Factors ◽  
Production Mechanism ◽  
Charmed Baryon ◽  
Electron Positron ◽  
State Radiation

As the lightest charmed baryon, precision measurement of the pair production cross section of provides unprecedented experimental information for the investigation of baryon production mechanism. In addition, the extraction of the polar angle distributions of the outgoing in the annihilation of the electron–positron help to determine its electromagnetic form factors, which is currently the unique key to access the internal structure of the baryons. In this article, the measurement of process via the initial state radiation technique at Belle detector and direct electron–positron annihilation at BESIII with discrete center-of-mass energies near threshold are briefly reviewed. In addition, the electromagnetic form factor ratios of measured by BESIII are also investigated. A few theoretical models that parameterize the center-of-mass energy dependence of the cross section and electromagnetic form factors of baryon are introduced and the contributions of data to them are discussed.

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