20 research outputs found
Studying the production mechanisms of light meson resonances in two-pion photoproduction: a Regge approach
A calculation of the angular moments of two-pion photoproduction is
presented. The underlying theoretical model encodes the prominent
resonance and the expected leading background contribution coming from the Deck
mechanism. The model contains a number of free parameters which are fit to
experimental data. A good description of the angular moments is obtained.Comment: 5 pages, 3 figures. Prepared as proceedings contribution for the 20th
International Conference on Hadron Spectroscopy and Structure (HADRON 2023),
Genova, Italy, 5-9/6/202
Deep learning exotic hadrons
We perform the first amplitude analysis of experimental data using deep neural networks to determine the nature of an exotic hadron. Specifically, we study the line shape of the Pc(4312) signal reported by the LHCb collaboration, and we find that its most likely interpretation is that of a virtual state. This method can be applied to other near-threshold resonance candidates
Dynamics in near-threshold photoproduction
The study of photoproduction at low energies has consequences for
the understanding of multiple aspects of nonperturbative QCD, ranging from
mechanical properties of the proton, to the binding inside nuclei, and the
existence of hidden-charm pentaquarks. Factorization of the photon-
and nucleon dynamics or Vector Meson Dominance are often invoked to justify
these studies. Alternatively, open charm intermediate states have been proposed
as the dominant mechanism underlying photoproduction. As the latter
violates this factorization, it is important to estimate the relevance of such
contributions. We analyse the latest differential and integrated
photoproduction cross sections from the GlueX and -007 experiments. We
show that the data can be adequately described by a small number of partial
waves, which we parameterize with generic models enforcing low-energy
unitarity. The results suggest a nonnegligible contribution from open charm
intermediate states. Furthermore, most of the models present an elastic
scattering length incompatible with previous extractions based on Vector Meson
Dominance, and thus call into question its applicability to heavy mesons. Our
results indicate a wide array of physics possibilities that are compatible with
present data and need to be disentangled.Comment: 15 pages, 7 figures, 2 table
Khuri-Treiman analysis of
We study the decay within the framework of
the Khuri-Treiman equations. We find that the BESIII experimental di-pion mass
distribution in the -region is well reproduced with a
once-subtracted -wave amplitude. Furthermore, we show that -wave
contributions to the amplitude improve the description of the data in the
mass region around 1.5 GeV. We also present predictions for the
transition form factor.Comment: 20 pages, 9 figure
Deep learning exotic hadrons
We perform the first amplitude analysis of experimental data using deep neural networks to determine the nature of an exotic hadron. Specifically, we study the line shape of the P c ( 4312 ) signal reported by the LHCb collaboration, and we find that its most likely interpretation is that of a virtual state. This method can be applied to other near-threshold resonance candidates
First measurement of direct photoproduction on the proton
We report on the results of the first measurement of exclusive
meson photoproduction on protons for GeV and GeV. Data were collected with the CLAS detector at the Thomas
Jefferson National Accelerator Facility. The resonance was detected via its
decay in the channel by performing a partial wave analysis of the
reaction . Clear evidence of the meson
was found in the interference between and waves at GeV. The -wave differential cross section integrated in the mass range of
the was found to be a factor of 50 smaller than the cross section
for the meson. This is the first time the meson has been
measured in a photoproduction experiment
Strong Interaction Physics at the Luminosity Frontier with 22 GeV Electrons at Jefferson Lab
This document presents the initial scientific case for upgrading the
Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab)
to 22 GeV. It is the result of a community effort, incorporating insights from
a series of workshops conducted between March 2022 and April 2023. With a track
record of over 25 years in delivering the world's most intense and precise
multi-GeV electron beams, CEBAF's potential for a higher energy upgrade
presents a unique opportunity for an innovative nuclear physics program, which
seamlessly integrates a rich historical background with a promising future. The
proposed physics program encompass a diverse range of investigations centered
around the nonperturbative dynamics inherent in hadron structure and the
exploration of strongly interacting systems. It builds upon the exceptional
capabilities of CEBAF in high-luminosity operations, the availability of
existing or planned Hall equipment, and recent advancements in accelerator
technology. The proposed program cover various scientific topics, including
Hadron Spectroscopy, Partonic Structure and Spin, Hadronization and Transverse
Momentum, Spatial Structure, Mechanical Properties, Form Factors and Emergent
Hadron Mass, Hadron-Quark Transition, and Nuclear Dynamics at Extreme
Conditions, as well as QCD Confinement and Fundamental Symmetries. Each topic
highlights the key measurements achievable at a 22 GeV CEBAF accelerator.
Furthermore, this document outlines the significant physics outcomes and unique
aspects of these programs that distinguish them from other existing or planned
facilities. In summary, this document provides an exciting rationale for the
energy upgrade of CEBAF to 22 GeV, outlining the transformative scientific
potential that lies within reach, and the remarkable opportunities it offers
for advancing our understanding of hadron physics and related fundamental
phenomena.Comment: Updates to the list of authors; Preprint number changed from theory
to experiment; Updates to sections 4 and 6, including additional figure
Studying the Production Mechanisms of Light Meson Resonances in Two-Pion Photoproduction
Abstract. A theoretical model of two-pion photoproduction is presented. The model encodes the prominent ρ(770) resonance and the expected leading background contribution coming from the Deck mechanism. To validate the model, angular moments are computed and compared with the CLAS dataset. After fitting a number of free parameters, the model provides a good description of the data
Dynamics in near-threshold J / ψ photoproduction
2023 Descuentos SCOAPThe study of J/ψ photoproduction at low energies has consequences for the understanding of multiple aspects of nonperturbative QCD, ranging from mechanical properties of the proton to the binding inside nuclei and the existence of hidden-charm pentaquarks. Factorization of the photon-cc¯ and nucleon dynamics or vector meson dominance are often invoked to justify these studies. Alternatively, open-charm intermediate states have been proposed as the dominant mechanism underlying J/ψ photoproduction. As the latter violates this factorization, it is important to estimate the relevance of such contributions. We analyze the latest differential and integrated photoproduction cross sections from the GlueX and J/ψ-007 experiments. We show that the data can be adequately described by a small number of partial waves, which we parametrize with generic models enforcing low-energy unitarity. The results suggest a non-negligible contribution from open-charm intermediate states. Furthermore, most of the models present an elastic scattering length incompatible with previous extractions based on vector meson dominance and thus call into question its applicability to heavy mesons. Our results indicate a wide array of physics possibilities that are compatible with present data and need to be disentangled.U.S. Department of EnergyU.S. National Science FoundationMinisterio de Ciencia e Innovación (España)National Natural Science Foundation of ChinaDeutsche Forschungsgemeinschaft (DFG)Ministerio de Educación y Formación Profesional (España)Generalitat ValencianaNational Science Center (Poland)Depto. de Física TeóricaFac. de Ciencias FísicasInstituto de Física de Partículas y del Cosmos (IPARCOS)TRUEpu