119 research outputs found
Baryonic Regge trajectories with analyticity constraints
A model for baryonic Regge trajectories compatible with the threshold
behavior required by unitarity and asymptotic behavior in agreement with
analyticity constraints is given in explicit form. Widths and masses of the
baryonic resonances on the N and trajectories are reproduced. The
MacDowell symmetry is exploited and an application is given.Comment: 12 pages, 6 figure
J/Psi Photoproduction in a Dual Model
J/Psi photoproduction is studied in the framework of the analytic S-matrix
theory. The differential and integrated elastic cross sections for J/Psi
photoproduction are calculated from a Dual Amplitude with Mandelstam
Analyticity. It is argued that at low energies, the background, which is the
low-energy equivalent of the high-energy diffraction replaces the Pomeron
exchange. The onset of the high energy Pomeron dominance is estimated from the
fits to the data.Comment: 10 pages, 7 figures. Dedicated to Professor Anatoly I. Bugrij on the
occasion of his 60-th birthda
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
A facility to Search for Hidden Particles (SHiP) at the CERN SPS
A new general purpose fixed target facility is proposed at the CERN SPS
accelerator which is aimed at exploring the domain of hidden particles and make
measurements with tau neutrinos. Hidden particles are predicted by a large
number of models beyond the Standard Model. The high intensity of the SPS
400~GeV beam allows probing a wide variety of models containing light
long-lived exotic particles with masses below (10)~GeV/c,
including very weakly interacting low-energy SUSY states. The experimental
programme of the proposed facility is capable of being extended in the future,
e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa
Forward Physics at the LHC; Elastic Scattering
The following effects in the nearly forward ("soft") region of the LHC are
proposed to be investigated: 1) At small |t| the fine structure of the cone
(Pomeron) shouldbe scrutinized: a) a break of the cone near ^2, due to the two-pion threshold, and required by t-channel unitarity, is
expected, and b) possible small-period oscillations between and the dip
region. 2) In measuring the elastic scattering and total cross
section at the LHC, the experimentalists are urged to treat the total cross
section the ratio , the forward slope and the luminosity
as free arameters, and to publish model-independent results on
3) Of extreme interest are the details of the expected diffraction
minimum in the differential cross section. Its position, expected in the
interval GeV at the level of about
GeV GeV, cannot be predicted
unambiguously, and its depth, i.e. the ratio of at the minimum to
that at the subsequent maximum (about GeV, which is about 5 is of
great importance. 4) The expected slow-down with increasing of the
shrinkage of the second cone (beyond the dip-bump), together with the
transition from an exponential to a power decrease in , will be indicative
of the transition from "soft" to "hard" physics. Explicit models are proposed
to help in quantifying this transition. 5) In a number of papers a limiting
behavior, or saturation of the black disc limit (BDL) was predicted. This
controversial phenomenon shows that the BDL may not be the ultimate limit.Comment: pp. 50, figs 16 (typos corrected
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
- …