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## Nuclear Forces from Lattice Quantum Chromodynamics

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 18/09/2013
Português

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A century of coherent experimental and theoretical investigations have
uncovered the laws of nature that underly nuclear physics. The standard model
of strong and electroweak interactions, with its modest number of input
parameters, dictates the dynamics of the quarks and gluons - the underlying
building blocks of protons, neutrons, and nuclei. While the analytic techniques
of quantum field theory have played a key role in understanding the dynamics of
matter in high energy processes, they encounter difficulties when applied to
low-energy nuclear structure and reactions, and dense systems. Expected
increases in computational resources into the exa-scale during the next decade
will provide the ability to numerically compute a range of important strong
interaction processes directly from QCD with quantifiable uncertainties using
the technique of Lattice QCD. These calculations will refine the chiral nuclear
forces that are used as input into nuclear many-body calculations, including
the three- and four-nucleon interactions. I discuss the state-of-the-art
Lattice QCD calculations of quantities of interest in nuclear physics, progress
that is expected in the near future, and the impact upon nuclear physics.; Comment: Presentation at the International Conference on Nuclear Theory in the
Supercomputing Era -2013...

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## Initiative in Nuclear Theory at the Variable Energy Cyclotron Centre

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 24/06/2005
Português

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We recall the path breaking contributions of the nuclear theory group of the
Variable Energy Cyclotron Centre, Kolkata. From a beginning of just one person
in 1970s, the group has steadily developed into a leading group in the country
today, with seminal contributions to almost the entire range of nuclear
physics, viz., low energy nuclear reactions, nuclear structure, deep inelastic
collisions, fission, liquid to gas phase transitions, nuclear matter, equation
of state, mass formulae, neutron stars, relativistic heavy ion collisions,
medium modification of hadron properties, quark gluon plasma, and cosmology of
early universe.; Comment: Lecture given at the special session, "Reflections" during Workshop
on Changing Scales in Nuclear Physics at Variable Energy Cyclotron Centre,
Kolkata during June 14-15, 2005 to honour Prof. Bikash Sinha on his 60th
birth day. 48 pages, 12 figures

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## Nuclear forces and ab initio calculations of atomic nuclei

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 21/01/2014
Português

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#Nuclear Theory#High Energy Physics - Lattice#High Energy Physics - Phenomenology#Nuclear Experiment

Nuclear forces and the nuclear many-body problem have been some of Gerry
Brown's main topics in his so productive life as a theoretical physicist. In
this talk, I outline how Gerry's work laid the foundations of the modern theory
of nuclear forces and ab initio calculations of atomic nuclei. I also present
some recent developments obtained in the framework of nuclear lattice
simulations.; Comment: Contribution to "45 years of nuclear theory at Stony Brook: a tribute
to Gerald E. Brown", uses elsarticle.cls

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## Interactions, symmetry breaking, and effective fields from quarks to nuclei. (A primer in nuclear theory)

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 22/01/2003
Português

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An introduction to nuclear theory is given starting from the quantum
chromodynamics foundations for quark and gluon fields, then discussing
properties of pions and nucleons, interactions between nucleons, structure of
the deuteron and light nuclei, and finishing at the description of heavy
nuclei. It is shown how concepts of different energy and size scales and ideas
related to effective fields and symmetry breaking, enter our description of
nuclear systems.; Comment: 43 pages, 10 EPS figures. Lecture notes at the Joliot-Curie
International School, Maubuisson 2002

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## Uncertainty analysis and order-by-order optimization of chiral nuclear interactions

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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Chiral effective field theory (chiEFT) provides a systematic approach to
describe low-energy nuclear forces. Moreover, chiEFT is able to provide
well-founded estimates of statistical and systematic uncertainties -- although
this unique advantage has not yet been fully exploited. We fill this gap by
performing an optimization and statistical analysis of all the low-energy
constants (LECs) up to next-to-next-to-leading order. Our optimization protocol
corresponds to a simultaneous fit to scattering and bound-state observables in
the pion-nucleon, nucleon-nucleon, and few-nucleon sectors, thereby utilizing
the full model capabilities of chiEFT. We study the effect on other observables
by demonstrating error-propagation methods that can easily be adopted by future
works. We employ mathematical optimization and implement automatic
differentiation to attain efficient and machine-precise first- and second-order
derivatives of the objective function with respect to the LECs. We use
power-counting arguments to estimate the systematic uncertainty that is
inherent to chiEFT and we construct chiral interactions at different orders
with quantified uncertainties. Statistical error propagation is compared with
Monte Carlo sampling showing that statistical errors are in general small
compared to systematic ones. In conclusion...

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## Modeling nuclear parton distribution functions

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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The presence of nuclear medium and collective phenomena which involve several
nucleons modify the parton distribution functions of nuclei (nPDFs) compared to
those of a free nucleon. These modifications have been investigated by
different groups using global analyses of high energy nuclear reaction world
data resulting in modern nPDF parametrizations with error estimates, such as
EPS09(s), HKN07 and nDS. These phenomenological nPDF sets roughly agree within
their uncertainty bands, but have antiquarks for large-$x$ and gluons for the
whole $x$-range poorly constrained by the available data. In the kinematics
accessible at the LHC this has negative impact on the interpretation of the
heavy-ion collision data, especially for the $p + A$ benchmarking runs. The EMC
region is also sensitive to the proper definition of $x$, where the nuclear
binding effects have to be taken into account, and for heavy nuclei one also
needs to take into account that a fraction of the nucleus momentum is carried
by the equivalent photons which modifies the momentum sum rule. We study how
these effects affect the predictions for the nuclear modification ratios at the
LHC kinematics using a model where we combine theoretical input for the leading
twist nuclear shadowing (the FGS model) and the EKS98s/EPS09s nPDF set where
the spatial dependence is formulated as a power series of the nuclear thickness
functions $T_A$.; Comment: Prepared for the proceedings of International Conference on Nuclear
Theory in the Supercomputing Era - 2013; revised version

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## A Vision for Nuclear Theory: Report to NSAC

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 18/11/2003
Português

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This is the report of the NSAC Subcommittee on Nuclear Theory in response to
a charge by the funding agencies to review and evaluate current NSF and DOE
supported efforts in nuclear theory and identify strategic plans to ensure a
strong U.S. nuclear theory program under various funding scenarios.; Comment: Report of the NSAC Nuclear Theory Subcommittee

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## Novel effects of electromagnetic interaction on the correlation of nucleons in nuclear matter

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

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#Nuclear Theory#Astrophysics#Condensed Matter - Soft Condensed Matter#Condensed Matter - Strongly Correlated Electrons#General Relativity and Quantum Cosmology#High Energy Physics - Phenomenology#Nuclear Experiment#Quantum Physics

The electromagnetic(EM) interactions between charged protons on the
correlations of nucleons are discussed by introducing the Anderson-Higgs
mechanism of broken U(1) EM symmetry into the relativistic nuclear theory with
a parametric photon mass. The non-saturating Coulomb force contribution is
emphasized on the equation of state of nuclear matter with charge symmetry
breaking(CSB) at finite temperature and the breached $^1S_0$ pairing
correlations of proton-proton and neutron-neutron. The universal properties
given by an order parameter field with a non-zero vacuum expectation value
(VEV) nearby phase transition are explored within the mean field theory(MFT)
level. This mechanism can be extended to the charged or charge neutralized
strongly coupling multi-components system for the discussion of binding or
pairing issues.; Comment: 6 pages, 3 figues, revised according to comments; improved with typos
corrected and updated references added; final published version in Phys.
Lett. B

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## Living on the edge of stability, the limits of the nuclear landscape

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 27/12/2012
Português

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A first-principles description of nuclear systems along the drip lines
presents a substantial theoretical and computational challenge. In this paper,
we discuss the nuclear theory roadmap, some of the key theoretical approaches,
and present selected results with a focus on long isotopic chains. An important
conclusion, which consistently emerges from these theoretical analyses, is that
three-nucleon forces are crucial for both global nuclear properties and
detailed nuclear structure, and that many-body correlations due to the coupling
to the particle continuum are essential as one approaches particle drip lines.
In the quest for a comprehensive nuclear theory, high performance computing
plays a key role.; Comment: Contribution to proceedings of Nobel Symposium 152: Physics with
radioactive beams, June 2012, Gothenburg, Sweden

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## Annual Report for the Department of Energy: 1999-2000, Nuclear Theory Group at the University of Washington

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 14/07/2000
Português

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This document is a summary of the physics research carried out by the Nuclear
Theory Group at the University of Washington during the last twelve-month
period, 1999-2000.; Comment: 33 pages, 5 eps figure, latex

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## Light Front Nuclear Theory and the HERMES Effect

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 21/11/2000
Português

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I discuss the use of light cone variables to compute the nucleonic and
mesonic components of nuclear wave functions. A Lagrangian and its
energy-momentum tensor $T^{^+\mu}$ is used to define the total momentum
operators $P^\mu$. The aim is to use wave functions, expressed in terms of
plus-momentum variables, which are used to analyze high energy experiments such
as deep inelastic scattering, Drell-Yan production, (e,e') and (p,p')
reactions. We discuss infinite nuclear matter within the mean field
approximation; finite nuclei using the mean field approximation;
nucleon-nucleon scattering, within the one boson exchange approximation; and,
infinite nuclear matter including the effects of two-nucleon correlations.
Standard good results for nuclear saturation properties are obtained, with a
possible improvement in the lowered value, 180 MeV, of the computed nuclear
compressibility. In our approach, manifest rotational invariance emerges at the
end of the calculation. Thus nuclear physics can be done in a manner in which
modern nuclear dynamics can be implemented and symmetries are respected. A
salient feature is that $\omega,\sigma$ and $\pi$ mesons are obtained as
important constituents. These can contribute coherently to enhance nuclear
electroproduction cross sections for longitudinal virtual photons at low $Q^2$...

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## A way forward in the study of the symmetry energy: experiment, theory, and observation

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 22/01/2014
Português

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The symmetry energy describes how the energy of nuclear matter rises as one
goes away from equal numbers of neutrons and protons. This is very important to
describe neutron rich matter in astrophysics. This article reviews our
knowledge of the symmetry energy from theoretical calculations, nuclear
structure measurements, heavy ion collisions, and astronomical observations. We
then present a roadmap to make progress in areas of relevance to the symmetry
energy that promotes collaboration between the astrophysics and the nuclear
physics communities.; Comment: 19 pages, results from first International Collaborations in Nuclear
Theory (ICNT) program at NSCL/FRIB, submitted to J. Phys G

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## Nuclear Theory and Science of the Facility for Rare Isotope Beams

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 24/01/2014
Português

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#Nuclear Theory#Astrophysics - Cosmology and Nongalactic Astrophysics#Astrophysics - Astrophysics of Galaxies#Astrophysics - Solar and Stellar Astrophysics#Nuclear Experiment

The Facility for Rare Isotope Beams (FRIB) will be a world-leading laboratory
for the study of nuclear structure, reactions and astrophysics. Experiments
with intense beams of rare isotopes produced at FRIB will guide us toward a
comprehensive description of nuclei, elucidate the origin of the elements in
the cosmos, help provide an understanding of matter in neutron stars, and
establish the scientific foundation for innovative applications of nuclear
science to society. FRIB will be essential for gaining access to key regions of
the nuclear chart, where the measured nuclear properties will challenge
established concepts, and highlight shortcomings and needed modifications to
current theory. Conversely, nuclear theory will play a critical role in
providing the intellectual framework for the science at FRIB, and will provide
invaluable guidance to FRIB's experimental programs. This article overviews the
broad scope of the FRIB theory effort, which reaches beyond the traditional
fields of nuclear structure and reactions, and nuclear astrophysics, to explore
exciting interdisciplinary boundaries with other areas.
\keywords{Nuclear Structure and Reactions. Nuclear
Astrophysics. Fundamental Interactions. High Performance
Computing. Rare Isotopes. Radioactive Beams.; Comment: 20 pages...

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## Nuclear Reactions from Lattice QCD

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

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One of the overarching goals of nuclear physics is to rigorously compute
properties of hadronic systems directly from the fundamental theory of strong
interactions, Quantum Chromodynamics (QCD). In particular, the hope is to
perform reliable calculations of nuclear reactions which will impact our
understanding of environments that occur during big bang nucleosynthesis, the
evolution of stars and supernovae, and within nuclear reactors and high
energy/density facilities. Such calculations, being truly ab initio, would
include all two-nucleon and three- nucleon (and higher) interactions in a
consistent manner. Currently, lattice QCD provides the only reliable option for
performing calculations of some of the low- energy hadronic observables. With
the aim of bridging the gap between lattice QCD and nuclear many-body physics,
the Institute for Nuclear Theory held a workshop on Nuclear Reactions from
Lattice QCD on March 2013. In this review article, we report on the topics
discussed in this workshop and the path planned to move forward in the upcoming
years.; Comment: 35 pages, 13 figures, 1 table, review article for the "Nuclear
Reactions from Lattice QCD" workshop hosted by the Institute for Nuclear
Theory on March 2013; version 2 includes updated references and extended
discussion of previous work

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## Light Front Nuclear Theory

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 06/09/2001
Português

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High energy scattering experiments involving nuclei are typically analyzed in
terms of light front variables. The desire to provide realistic,relativistic
wave functions expressed in terms of these variables led me to try to use light
front dynamics to compute nuclear wave functions. Here calculations of infinite
nuclear matter in the mean field approximation and also in a light front
version of Bruckner theory which includes NN correlations are reviewed.
Applications of these wave functions to nuclear deep inelastic scattering and
Drell-Yan processes are discussed. We find that relativistic mean field theory
produces no EMC binding effect.; Comment: For Proceedings of 3rd International Conference on Perspectives in
Hadronic Physics, May 2001

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## Challenges for Modeling Nuclear Structure: Are the Proton and Neutron Masses and A-body Interactions Relevant?

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 26/11/2010
Português

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We discuss some of the challenges that future nuclear modeling may face in
order to improve the description of the nuclear structure. One challenge is
related to the need for A-body nuclear interactions justified by various
contemporary nuclear physics studies. Another challenge is related to the
discrepancy in the NNN contact interaction parameters for 3He and 3H that
suggests the need for accurate proton and neutron masses in the future
precision calculations.
MSC2010 Classification: 17B81 Applications to physics, 17B80 Applications to
integrable systems, 81R12 Relations with integrable systems, 81V70 Many-body
theory, 81V35 Nuclear physics, 81U15 Exactly and quasi-solvable systems, 82B23
Exactly solvable models; Bethe ansatz.; Comment: 13 pages, 6 figures, Contribution to the XXIX International Workshop
on Nuclear Theory, June 20 - 26, 2010, Rila Mountains, Bulgaria

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## Many-body interactions and nuclear structure

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 07/03/2010
Português

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This article presents several challenges to nuclear many-body theory and our
understanding of the stability of nuclear matte r. In order to achieve this, we
present five different cases, starting with an idealized toy model. These cases
expose problems that need to be understood in order to match recent advances in
nuclear theory with current experimental programs in low-energy nuclear
physics. In particular, we focus on our current understanding, or lack thereof,
of many-body forces, and how they evolve as functions of the number of
particles . We provide examples of discrepancies between theory and experiment
and outline some selected perspectives for future research directions.; Comment: 26 pages and 6 figures, IOP latex style. Subimtted to Journal of
Physics G, Focus issue on open problems in Nuclear structure theory

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## The Nuclear Force Problem: Is the Never-Ending Story Coming to an End?

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 18/09/2006
Português

Relevância na Pesquisa

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The attempts to find the right (underlying) theory for the nuclear force have
a long and stimulating history. Already in 1953, Hans Bethe stated that "more
man-hours have been given to this problem than to any other scientific question
in the history of mankind". In search for the nature of the nuclear force, the
idea of sub-nuclear particles was created which, eventually, generated the
field of particle physics. I will review this productive history of hope,
error, and desperation. Finally, I will discuss recent ideas which apply the
concept of an effective field theory to low-energy QCD. There are indications
that this concept may provide the right framework to properly understand
nuclear forces.; Comment: 10 pages, 2 figures, talk at XXV International Workshop on Nuclear
Theory, June 26-July 1, 2005, Rila Mountains, Bulgaria

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## Pion Excess, Nuclear Correlations, and the Interpretation of ($\vec p, \vec n$) Spin Transfer Experiments

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 16/09/1997
Português

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Conventional theories of nuclear interactions predict a net increase in the
distribution of virtual pions in nuclei relative to free nucleons. Analysis of
data from several nuclear experiments has led to claims of evidence against
such a pion excess. These conclusions are usually based on a collective theory
(RPA) of the pions, which may be inadequate. The issue is the energy dependence
of the nuclear response, which differs for theories with strong NN correlations
from the RPA predictions. In the present paper, information about the energy
dependence is extracted from sum rules, which are calculated for such a
correlated, noncollective nuclear theory. The results lead to much reduced
sensitivity of nuclear reactions to the correlations that are responsible for
the pion excess. The primary example is $(\vec p,\vec n)$ spin transfer, for
which the expected effects are found to be smaller than the experimental
uncertainties. The analysis has consequences for Deep Inelastic Scattering
(DIS) experiments as well.; Comment: 16 pages, LaTeX, no figures, submitted to Phys. Rev. C

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## NUCLEAR THEORY WHITE PAPER 1995

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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We review the accomplishments of nuclear theory during the past five years and
identify the future challenges and research opportunities. [Final,
substantially revised version of the nuclear theory white paper]; Comment: 33 pages, LaTeX, 6 figures in uuencoded PostScript files

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