2
2.0

Jun 28, 2018
06/18

by
R. Schiavilla

texts

######
eye 2

######
favorite 0

######
comment 0

A status report on $\chi$EFT studies of few-nucleon electroweak structure and dynamics is provided, including electromagnetic form factors of few-nucleon systems, the $pp$ weak fusion and muon weak captures on deuteron and $^3$He, and a number of parity-violating processes induced by hadronic weak interactions.

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1510.05689

42
42

Sep 19, 2013
09/13

by
R. Schiavilla

texts

######
eye 42

######
favorite 0

######
comment 0

Our current understanding of the structure of nuclei with up to A=8, including energy spectra, electromagnetic form factors, and weak transitions, is reviewed within the context of a realistic approach to nuclear dynamics based on two- and three- nucleon interactions and associated electro-weak currents. Low-energy radiative and weak capture reactions of astrophysical relevance involving these light systems are also discussed.

Source: http://arxiv.org/abs/nucl-th/0010061v1

33
33

Sep 18, 2013
09/13

by
R. Schiavilla

texts

######
eye 33

######
favorite 0

######
comment 0

The status of "ab initio" microscopic calculations of the 2H(p,gamma)3He and 3He(p,e+nu_e)4He reactions is reviewed. The methods used to generate accurate nuclear ground- and scattering-state wave functions, and to construct realistic electro-weak transition operators are described. The uncertainties in the theoretical predictions, particularly those relevant to the p-3He weak capture, are discussed. For the dp radiative capture, the theoretical results are compared with the TUNL data...

Source: http://arxiv.org/abs/nucl-th/0006026v1

28
28

Sep 18, 2013
09/13

by
R. Schiavilla

texts

######
eye 28

######
favorite 0

######
comment 0

The induced polarization, $P^\prime_y$, of the neutron in the deuteron photo-disintegration from threshold up to 30 MeV is calculated using a variety of different, latest-generation potentials--Argonne $v_{18}$, Bonn 2000, and Nijmegen I-- and a realistic model for the nuclear electromagnetic current operator, including one- and two-body terms. The model dependence of the theoretical predictions is found to be very small. These predictions are systematically larger in magnitude than the...

Source: http://arxiv.org/abs/nucl-th/0505066v1

31
31

Sep 19, 2013
09/13

by
R. Schiavilla

texts

######
eye 31

######
favorite 0

######
comment 0

Our current understanding of the structure of nuclei with up to A=8, including energy spectra, electromagnetic form factors, and capture reactions, is critically reviewed within the context of a realistic approach to nuclear dynamics based on two- and three-nucleon interactions and associated electromagnetic currents.

Source: http://arxiv.org/abs/nucl-th/0010062v1

42
42

Jul 20, 2013
07/13

by
R. Schiavilla; I. Sick

texts

######
eye 42

######
favorite 0

######
comment 0

The neutron charge form factor $G_{En}(q)$ is determined from an analysis of the deuteron quadrupole form factor $F_{C2}$ data. Recent calculations, based on a variety of different model interactions and currents, indicate that the contributions associated with the uncertain two-body operators of shorter range are relatively small for $F_{C2}$, even at large momentum transfer $q$. Hence, $G_{En}(q)$ can be extracted from $F_{C2}$ at large $q^2$ without undue systematic uncertainties from theory.

Source: http://arxiv.org/abs/nucl-ex/0107004v1

41
41

Sep 18, 2013
09/13

by
A. Arriaga; R. Schiavilla

texts

######
eye 41

######
favorite 0

######
comment 0

The threshold electrodisintegration of the deuteron at backward angles is studied with a relativistic Hamiltonian, including a relativistic one-pion-exchange potential (OPEP) with off-shell terms as predicted by pseudovector coupling of pions to nucleons. The bound and scattering states are obtained in the center-of-mass frame, and then boosted from it to the Breit frame, where the evaluation of the relevant matrix elements of the electromagnetic current operator is carried out. The latter...

Source: http://arxiv.org/abs/0704.2514v1

2
2.0

Jun 29, 2018
06/18

by
D. O. Riska; R. Schiavilla

texts

######
eye 2

######
favorite 0

######
comment 0

The development of the chiral dynamics based description of nuclear electroweak currents is reviewed. Gerald E. (Gerry) Brown's role in basing theoretical nuclear physics on chiral Lagrangians is emphasized. Illustrative examples of the successful description of electroweak observables of light nuclei obtained from chiral effective field theory are presented.

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1603.01253

41
41

Sep 22, 2013
09/13

by
R. B. Wiringa; R. Schiavilla

texts

######
eye 41

######
favorite 0

######
comment 0

Variational Monte Carlo wave functions, obtained from a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana-IX three-nucleon interactions, are used to calculate the 6Li ground-state longitudinal and transverse form factors as well as transition form factors to the first four excited states. The charge and current operators include one- and two-body components, leading terms of which are constructed consistently with the two-nucleon interaction. The calculated form factors...

Source: http://arxiv.org/abs/nucl-th/9807037v2

45
45

Sep 22, 2013
09/13

by
R. Schiavilla; R. B. Wiringa

texts

######
eye 45

######
favorite 0

######
comment 0

The $^6$He beta decay and $^7$Be electron capture processes are studied using variational Monte Carlo wave functions, derived from a realistic Hamiltonian consisting of the Argonne $v_{18}$ two-nucleon and Urbana-IX three-nucleon interactions. The model for the nuclear weak axial current includes one- and two-body operators with the strength of the leading two-body term--associated with $\Delta$-isobar excitation of the nucleon--adjusted to reproduce the Gamow-Teller matrix element in tritium...

Source: http://arxiv.org/abs/nucl-th/0201076v1

43
43

Sep 22, 2013
09/13

by
R. Schiavilla; V. R. Pandharipande

texts

######
eye 43

######
favorite 0

######
comment 0

What range of momentum components in the deuteron wave function are available e d elastic scattering data sensitive to ? This question is addressed within the context of a model calculation of the deuteron form factors, based on realistic interactions and currents. It is shown that the data on the $A(q)$, $B(q)$, and $T_{20}(q)$ observables at $q \leq 6$ fm$^{-1}$ essentially probe momentum components up to $\simeq 4 m_\pi$.

Source: http://arxiv.org/abs/nucl-th/0201043v1

49
49

Sep 20, 2013
09/13

by
R. Schiavilla; J. Carlson; M. Paris

texts

######
eye 49

######
favorite 0

######
comment 0

We investigate parity-violating observables in the np system, including the longitudinal asymmetry and neutron-spin rotation in np elastic scattering, the photon asymmetry in np radiative capture, and the asymmetries in deuteron photo-disintegration d(gamma,n)p in the threshold region and electro-disintegration d(e,e`)np in quasi-elastic kinematics. To have an estimate of the model dependence for the various predictions, a number of different, latest-generation strong-interaction...

Source: http://arxiv.org/abs/nucl-th/0404082v1

38
38

Sep 18, 2013
09/13

by
R. Schiavilla; J. Carlson; M. Paris

texts

######
eye 38

######
favorite 0

######
comment 0

We investigate parity-violating asymmetries in polarized n p radiative capture, and deuteron electro-disintegration in quasi-elastic kinematics, using the DDH model for the parity-violating nucleon-nucleon interaction. We find dramatic cancellations between the asymmetries induced by the parity-violating interaction and those arising from the associated parity-violating pion-exchange currents. In np capture, the model-dependence of the result is nevertheless quite small because of constraints...

Source: http://arxiv.org/abs/nucl-th/0212038v1

40
40

Sep 22, 2013
09/13

by
R. Schiavilla; R. B. Wiringa; J. Carlson

texts

######
eye 40

######
favorite 0

######
comment 0

In simple models of the nuclear charge operator, measurements of the Coulomb sum and the charge form factor of a nucleus directly determine the proton-proton correlations. We examine experimental results obtained for few-body nuclei at Bates and Saclay using models of the charge operator that include both one- and two-body terms. Previous analyses using one-body terms only have failed to reproduce experimental results. However, we find that the same operators which have been used to...

Source: http://arxiv.org/abs/nucl-th/9302013v2

42
42

Sep 23, 2013
09/13

by
S. Pastore; R. Schiavilla; J. L. Goity

texts

######
eye 42

######
favorite 0

######
comment 0

Nuclear electromagnetic currents are derived in time-ordered perturbation theory within an effective-field-theory framework including explicit nucleons, $\Delta$ isobars, and pions up to one loop, or N$^3$LO. The currents obtained at N$^2$LO, {\it i.e.} ignoring loop corrections, are used in a study of neutron radiative captures on protons and deuterons at thermal energies, and of $A$=2 and 3 nuclei magnetic moments. The wave functions for $A$=2 are derived from solutions of the...

Source: http://arxiv.org/abs/0810.1941v2

32
32

Sep 18, 2013
09/13

by
S. Pastore; R. Schiavilla; J. L. Goity

texts

######
eye 32

######
favorite 0

######
comment 0

Nuclear electromagnetic currents derived in a chiral-effective-field-theory framework including explicit nucleons, $\Delta$ isobars, and pions up to N$^2$LO, {\it i.e.} ignoring loop corrections, are used in a study of neutron radiative captures on protons and deuterons at thermal energies, and of $A$=2 and 3 nuclei magnetic moments. With the strengths of the $\Delta$-excitation currents determined to reproduce the $n$-$p$ cross section and isovector combination of the trinucleon magnetic...

Source: http://arxiv.org/abs/0809.2555v1

37
37

Sep 22, 2013
09/13

by
L. Diaconescu; R. Schiavilla; U. van Kolck

texts

######
eye 37

######
favorite 0

######
comment 0

The longitudinal asymmetry due to $Z^0$ exchange is calculated in quasi-elastic electron-deuteron scattering at momentum transfers $|Q^2| \simeq 0.1$ GeV$^2$ relevant for the SAMPLE experiment. The deuteron and $pn$ scattering-state wave functions are obtained from solutions of a Schr\"odinger equation with the Argonne $v_{18}$ potential. Electromagnetic and weak neutral one- and two-nucleon currents are included in the calculation. The two-nucleon currents of pion range are shown to be...

Source: http://arxiv.org/abs/nucl-th/0011034v1

28
28

Sep 22, 2013
09/13

by
L. Girlanda; S. Pastore; R. Schiavilla; M. Viviani

texts

######
eye 28

######
favorite 0

######
comment 0

We construct the most general, relativistically invariant, contact Lagrangian at order Q^2 in the power counting, Q denoting the low momentum scale. A complete, but non-minimal, set of (contact) interaction terms is identified, which upon non-relativistic reduction generate 2 leading independent operator combinations of order Q^0 and 7 sub-leading ones of order Q^2 - a result derived previously in the heavy-baryon formulation of effective field theories (EFT's). We show that Poincare covariance...

Source: http://arxiv.org/abs/1001.3676v1

44
44

Sep 17, 2013
09/13

by
L. Girlanda; S. Pastore; R. Schiavilla; M. Viviani

texts

######
eye 44

######
favorite 0

######
comment 0

Recently, we have derived a two--nucleon potential and consistent nuclear electromagnetic currents in chiral effective field theory with pions and nucleons as explicit degrees of freedom. The calculation of the currents has been carried out to include N$^3$LO corrections, consisting of two--pion exchange and contact contributions. The latter involve unknown low-energy constants (LECs), some of which have been fixed by fitting the $np$ S- and P-wave phase shifts up to 100 MeV lab energies. The...

Source: http://arxiv.org/abs/0912.2763v1

34
34

Sep 22, 2013
09/13

by
J. Carlson; J. Jourdan; R. Schiavilla; I. Sick

texts

######
eye 34

######
favorite 0

######
comment 0

The $^3$He and $^4$He longitudinal and transverse response functions are determined from an analysis of the world data on quasi-elastic inclusive electron scattering. The corresponding Euclidean response functions are derived and compared to those calculated with Green's function Monte Carlo methods, using realistic interactions and currents. Large contributions associated with two-body currents are found, particularly in the $^4$He transverse response, in agreement with data. The contributions...

Source: http://arxiv.org/abs/nucl-th/0106047v1

34
34

Sep 22, 2013
09/13

by
L. E. Marcucci; D. O. Riska; R. Schiavilla

texts

######
eye 34

######
favorite 0

######
comment 0

The electromagnetic form factors of the trinucleons 3H and 3He are calculated with wave functions obtained with the Argonne AV18 two-nucleon and Urbana IX three-nucleon interactions. Full account is taken of the two-body currents required by current conservation with the AV18 interaction as well as those associated with N-Delta transition currents and the currents of Delta resonance components in the wave functions. Explicit three-nucleon current operators associated with the two-pion exchange...

Source: http://arxiv.org/abs/nucl-th/9805048v1

27
27

Sep 19, 2013
09/13

by
M. J. Musolf; R. Schiavilla; T. W. Donnelly

texts

######
eye 27

######
favorite 0

######
comment 0

Meson-exchange current (MEC) contributions to the parity-violating (PV) asymmetry for elastic scattering of polarized electrons from $^4$He are calculated over a range of momentum transfer using Monte Carlo methods and a variational $^4$He ground state wavefunction. The results indicate that MEC's generate a negligible contribution to the asymmetry at low-$|\qv|$, where a determination of the nucleon's mean square strangeness radius could be carried out at CEBAF. At larger values of momentum...

Source: http://arxiv.org/abs/nucl-th/9405012v1

43
43

Sep 18, 2013
09/13

by
K. M. Nollett; R. B. Wiringa; R. Schiavilla

texts

######
eye 43

######
favorite 0

######
comment 0

We have computed the cross section for the process d + alpha -> 6Li + gamma at the low energies relevant for primordial nucleosynthesis and comparison with laboratory data. The final state is a six-body wave function generated by the variational Monte Carlo method from the Argonne v_18 and Urbana IX potentials, including improved treatment of large-particle-separation behavior. The initial state is built up from the alpha-particle and deuteron ground-state solutions for these potentials,...

Source: http://arxiv.org/abs/nucl-th/0006064v2

32
32

Sep 21, 2013
09/13

by
S. Pastore; L. Girlanda; R. Schiavilla; M. Viviani

texts

######
eye 32

######
favorite 0

######
comment 0

The electromagnetic charge operator in a two-nucleon system is derived in chiral effective field theory ($\chi$EFT) up to order $e\, Q$ (or N4LO), where $Q$ denotes the low-momentum scale and $e$ is the electric charge. The specific form of the N3LO and N4LO corrections from, respectively, one-pion-exchange and two-pion-exchange depends on the off-the-energy-shell prescriptions adopted for the non-static terms in the corresponding potentials. We show that different prescriptions lead to...

Source: http://arxiv.org/abs/1106.4539v1

40
40

Sep 17, 2013
09/13

by
L. Girlanda; S. Pastore; R. Schiavilla; M. Viviani

texts

######
eye 40

######
favorite 0

######
comment 0

We summarize our recent work dealing with the construction of the nucleon-nucleon potential and associated electromagnetic currents up to one loop in chiral effective field theory ($\chi$EFT). The magnetic dipole operators derived from these currents are then used in hybrid calculations of static properties and low-energy radiative capture processes in few-body nuclei. A preliminary set of results are presented for the magnetic moments of the deuteron and trinucleons and thermal neutron...

Source: http://arxiv.org/abs/0912.2753v1

48
48

Sep 24, 2013
09/13

by
R. B. Wiringa; V. G. J. Stoks; R. Schiavilla

texts

######
eye 48

######
favorite 0

######
comment 0

We present a new high-quality nucleon-nucleon potential with explicit charge dependence and charge asymmetry, which we designate Argonne $v_{18}$. The model has a charge-independent part with fourteen operator components that is an updated version of the Argonne $v_{14}$ potential. Three additional charge-dependent and one charge-asymmetric operators are added, along with a complete electromagnetic interaction. The potential has been fit directly to the Nijmegen $pp$ and $np$ scattering data...

Source: http://arxiv.org/abs/nucl-th/9408016v1

2
2.0

Jun 30, 2018
06/18

by
W. P. Ford; R. Schiavilla; J. W. Van Orden

texts

######
eye 2

######
favorite 0

######
comment 0

We present updated calculations for observables in the processes $^3$He($e,e^\prime p$)$^2$H, $^4$He($e,e^\prime p$)$^3$H, and $^4$He($\vec{e},e^\prime \vec{p}\,$)$^3$H. This update entails the implementation of improved nucleon-nucleon ($NN$) amplitudes to describe final state interactions (FSI) within a Glauber approximation and includes full spin-isospin dependence in the profile operator. In addition, an optical potential, which has also been updated since previous work, is utilized to...

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1401.4399

32
32

Sep 18, 2013
09/13

by
R. Schiavilla; R. B. Wiringa; Steven C. Pieper; J. Carlson

texts

######
eye 32

######
favorite 0

######
comment 0

Two-nucleon momentum distributions are calculated for the ground states of nuclei with mass number $A\leq 8$, using variational Monte Carlo wave functions derived from a realistic Hamiltonian with two- and three-nucleon potentials. The momentum distribution of $np$ pairs is found to be much larger than that of $pp$ pairs for values of the relative momentum in the range (300--600) MeV/c and vanishing total momentum. This order of magnitude difference is seen in all nuclei considered and has a...

Source: http://arxiv.org/abs/nucl-th/0611037v1

28
28

Sep 23, 2013
09/13

by
J. Carlson; R. Schiavilla; V. R. Brown; B. F. Gibson

texts

######
eye 28

######
favorite 0

######
comment 0

The proton-proton parity-violating longitudinal asymmetry is calculated in the lab-energy range 0--350 MeV, using a number of different, latest-generation strong-interaction potentials--Argonne V18, Bonn-2000, and Nijmegen-I--in combination with a weak-interaction potential consisting of rho- and omega-meson exchanges--the model known as DDH. The complete scattering problem in the presence of parity-conserving, including Coulomb, and parity-violating potentials is solved in both configuration-...

Source: http://arxiv.org/abs/nucl-th/0109084v1

32
32

Sep 23, 2013
09/13

by
S. Pastore; Steven C. Pieper; R. Schiavilla; R. B. Wiringa

texts

######
eye 32

######
favorite 0

######
comment 0

Quantum Monte Carlo calculations of electromagnetic moments and transitions are reported for A

Source: http://arxiv.org/abs/1212.3375v2

40
40

Sep 22, 2013
09/13

by
S. Pastore; Steven C. Pieper; R. Schiavilla; R. B. Wiringa

texts

######
eye 40

######
favorite 0

######
comment 0

We present recent Green's function Monte Carlo calculations of magnetic moments and M1 transitions in $A \leq 9$ nuclei, which include corrections arising from two-body meson-exchange electromagnetic currents. Two-body effects provide significant corrections to the calculated observables, bringing them in excellent agreement with the experimental data. In particular, we find that two-body corrections are especially large in the A=9, $T=3/2$ systems, in which they account for up to $\sim 20%$...

Source: http://arxiv.org/abs/1302.5091v1

10
10.0

Jun 28, 2018
06/18

by
A. Baroni; L. Girlanda; S. Pastore; R. Schiavilla; M. Viviani

texts

######
eye 10

######
favorite 0

######
comment 0

Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory, and accounts for cancellations between the contributions of irreducible diagrams and the contributions due to non-static corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and...

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1509.07039

64
64

Sep 22, 2013
09/13

by
J. L. Forest; V. R. Pandharipande; J. Carlson; R. Schiavilla

texts

######
eye 64

######
favorite 0

######
comment 0

In relativistic Hamiltonians the two-nucleon interaction is expressed as a sum of $\tilde{v}_{ij}$, the interaction in the ${\bf P}_{ij}=0$ rest frame, and the ``boost interaction'' $\delta v({\bf P}_{ij})$ which depends upon the total momentum ${\bf P}_{ij}$ and vanishes in the rest frame. The $\delta v$ can be regarded as a sum of four terms: $\delta v_{RE}$, $\delta v_{LC}$, $\delta v_{TP}$ and $\delta v_{QM}$; the first three originate from the relativistic energy-momentum relation, Lorentz...

Source: http://arxiv.org/abs/nucl-th/9410013v1

2
2.0

Jun 30, 2018
06/18

by
S. Pastore; R. B. Wiringa; Steven C. Pieper; R. Schiavilla

texts

######
eye 2

######
favorite 0

######
comment 0

We report quantum Monte Carlo calculations of electromagnetic transitions in 8Be. The realistic Argonne v18 two-nucleon and Illinois-7 three-nucleon potentials are used to generate the ground state and nine excited states, with energies that are in excellent agreement with experiment. A dozen M1 and eight E2 transition matrix elements between these states are then evaluated. The E2 matrix elements are computed only in impulse approximation, with those transitions from broad resonant states...

Topic: Nuclear Theory

Source: http://arxiv.org/abs/1406.2343

38
38

Sep 18, 2013
09/13

by
R. B. Wiringa; R. Schiavilla; Steven C. Pieper; J. Carlson

texts

######
eye 38

######
favorite 0

######
comment 0

Two-nucleon momentum distributions are calculated for the ground states of 3He and 4He as a function of the nucleons' relative and total momenta. We use variational Monte Carlo wave functions derived from a realistic Hamiltonian with two- and three-nucleon potentials. The momentum distribution of pp pairs is found to be much smaller than that of pn pairs for values of the relative momentum in the range (300--500) MeV/c and vanishing total momentum. However, as the total momentum increases to...

Source: http://arxiv.org/abs/0806.1718v1

62
62

Sep 22, 2013
09/13

by
S. Pastore; L. Girlanda; R. Schiavilla; M. Viviani; R. B. Wiringa

texts

######
eye 62

######
favorite 0

######
comment 0

A two-nucleon potential and consistent electromagnetic currents are derived in chiral effective field theory ($\chi$EFT) at, respectively, $Q^{2}$ (or N$^2$LO) and $e Q$ (or N$^3$LO), where $Q$ generically denotes the low-momentum scale and $e$ is the electric charge. Dimensional regularization is used to renormalize the pion-loop corrections. A simple expression is derived for the magnetic dipole ($M1$) operator associated with pion loops, consisting of two terms, one of which is determined,...

Source: http://arxiv.org/abs/0906.1800v2

3
3.0

Jun 26, 2018
06/18

by
F. Cavanna; O. Palamara; R. Schiavilla; M. Soderberg; R. B. Wiringa

texts

######
eye 3

######
favorite 0

######
comment 0

Improvements in theoretical modeling of Short Range structures and phenomena, and comparisons with data, will require sustained collaboration between nuclear theorists and neutrino experimentalists. The extensive history of studying this area of nuclear physics in electron- and hadron-scattering experiments, coupled with the transformative capabilities of LArTPCs to identify neutrinos, will provide a ripe opportunity for new discoveries that will further our understanding of the nucleus.

Topics: Nuclear Theory, Nuclear Experiment

Source: http://arxiv.org/abs/1501.01983

34
34

Sep 18, 2013
09/13

by
L. E. Marcucci; M. Viviani; A. Kievsky; S. Rosati; R. Schiavilla

texts

######
eye 34

######
favorite 0

######
comment 0

Recent advances in the study of the p-d radiative and mu-3he weak capture processes are presented and discussed. The three-nucleon bound and scattering states are obtained using the correlated-hyperspherical-harmonics method, with realistic Hamiltonians consisting of the Argonne v14 or Argonne v18 two-nucleon and Tucson-Melbourne or Urbana IX three-nucleon interactions. The electromagnetic and weak transition operators include one- and two-body contributions. The theoretical accuracy achieved...

Source: http://arxiv.org/abs/nucl-th/0212009v1

36
36

Sep 23, 2013
09/13

by
L. E. Marcucci; M. Viviani; R. Schiavilla; A. Kievsky; S. Rosati

texts

######
eye 36

######
favorite 0

######
comment 0

Recent advances in the study of electrodisintegration of 3He are presented and discussed. The pair-correlated hyperspherical harmonics method is used to calculate the initial and final state wave functions, with a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana IX three-nucleon interactions. The model for the nuclear current and charge operators retains one- and many-body contributions. Particular attention is made in the construction of the two-body current operators...

Source: http://arxiv.org/abs/nucl-th/0411082v1

30
30

Sep 24, 2013
09/13

by
L. E. Marcucci; A. Kievsky; S. Rosati; R. Schiavilla; M. Viviani

texts

######
eye 30

######
favorite 0

######
comment 0

The muon-capture reactions 2H(\mu^-,\nu_\mu)nn and 3He(\mu^-,\nu_\mu)3H are studied with nuclear strong-interaction potentials and charge-changing weak currents, derived in chiral effective field theory. The low-energy constants (LEC's) c_D and c_E, present in the three-nucleon potential and (c_D) axial-vector current, are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The vector weak current is related to the isovector component of the...

Source: http://arxiv.org/abs/1109.5563v2

51
51

Jul 20, 2013
07/13

by
M. Viviani; R. Schiavilla; L. Girlanda; A. Kievsky; L. E. Marcucci

texts

######
eye 51

######
favorite 0

######
comment 0

The longitudinal asymmetry induced by parity-violating (PV) components in the nucleon-nucleon potential is studied in the charge-exchange reaction 3He(n,p)3H at vanishing incident neutron energies. An expression for the PV observable is derived in terms of T-matrix elements for transitions from the {2S+1}L_J=1S_0 and 3S_1 states in the incoming n-3He channel to states with J=0 and 1 in the outgoing p-3H channel. The T-matrix elements involving PV transitions are obtained in first-order...

Source: http://arxiv.org/abs/1007.2052v1

29
29

Sep 22, 2013
09/13

by
R. Schiavilla; M. Viviani; L. Girlanda; A. Kievsky; L. E. Marcucci

texts

######
eye 29

######
favorite 0

######
comment 0

The neutron spin rotation induced by parity-violating (PV) components in the nucleon-nucleon potential is studied in \vec{n}-d scattering at zero energy. Results are obtained corresponding to the Argonne v_{18} two-nucleon and Urbana-IX three-nucleon strong-interaction potentials in combination with either the DDH or pionless EFT model for the weak-interaction potential. We find that this observable is dominated by the contribution of the long-range part of the PV potential associated with pion...

Source: http://arxiv.org/abs/0805.3599v1

40
40

Sep 22, 2013
09/13

by
L. E. Marcucci; R. Schiavilla; M. Viviani; A. Kievsky; S. Rosati

texts

######
eye 40

######
favorite 0

######
comment 0

The astrophysical factor for the proton weak capture on 3He is calculated with correlated-hyperspherical-harmonics bound and continuum wave functions corresponding to a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana-IX three-nucleon interactions. The nuclear weak charge and current operators have vector and axial-vector components, that include one- and many-body terms. All possible multipole transitions connecting any of the p-3He S- and P-wave channels to the 4He...

Source: http://arxiv.org/abs/nucl-th/0003065v1

8
8.0

Jun 26, 2018
06/18

by
A. Lovato; S. Gandolfi; J. Carlson; Steven C. Pieper; R. Schiavilla

texts

######
eye 8

######
favorite 0

######
comment 0

Ab initio calculations of the quasi-elastic electromagnetic and neutral-weak response functions of 4He and 12C are carried out for the first time. They are based on a realistic approach to nuclear dynamics, in which the strong interactions are described by two- and three-nucleon potentials and the electroweak interactions with external fields include one- and two-body terms. The Green's function Monte Carlo method is used to calculate directly the Laplace transforms of the response functions,...

Topics: High Energy Physics - Phenomenology, Nuclear Theory, High Energy Physics - Experiment

Source: http://arxiv.org/abs/1501.01981

34
34

Sep 21, 2013
09/13

by
L. E. Marcucci; Kenneth M. Nollett; R. Schiavilla; R. B. Wiringa

texts

######
eye 34

######
favorite 0

######
comment 0

We summarize recent ab initio studies of low-energy electroweak reactions of astrophysical interest, relevant for both big bang nucleosynthesis and solar neutrino production. The calculational methods include direct integration for np radiative and pp weak capture, correlated hyperspherical harmonics for reactions of A=3,4 nuclei, and variational Monte Carlo for A=6,7 nuclei. Realistic nucleon-nucleon and three-nucleon interactions and consistent current operators are used as input.

Source: http://arxiv.org/abs/nucl-th/0402078v1

31
31

Sep 23, 2013
09/13

by
L. E. Marcucci; M. Viviani; R. Schiavilla; A. Kievsky; S. Rosati

texts

######
eye 31

######
favorite 0

######
comment 0

Recent advances in the study of pd radiative capture in a wide range of center-of-mass energy below and above deuteron breakup threshold are presented and discussed.

Source: http://arxiv.org/abs/nucl-th/0411083v1

36
36

Sep 24, 2013
09/13

by
R. Schiavilla; O. Benhar; A. Kievsky; L. E. Marcucci; M. Viviani

texts

######
eye 36

######
favorite 0

######
comment 0

Polarization observables in the $^4$He$(\vec{e},e^\prime\vec{p})$$^3$H reaction are calculated using accurate three- and four-nucleon bound-state wave functions, a realistic model for the nuclear electromagnetic current operator, and a treatment of final-state-interactions with an optical potential. In contrast to earlier studies, no significant discrepancies are found between theory and experiment both for the ratio of transverse to longitudinal polarization transfers and for the induced...

Source: http://arxiv.org/abs/nucl-th/0412020v1

2
2.0

Jun 30, 2018
06/18

by
A. Lovato; S. Gandolfi; J. Carlson; Steven C. Pieper; R. Schiavilla

texts

######
eye 2

######
favorite 0

######
comment 0

An ab initio calculation of the sum rules of the neutral weak response functions in $^{12}$C is reported, based on a realistic Hamiltonian, including two- and three-nucleon potentials, and on realistic currents, consisting of one- and two-body terms. We find that the sum rules of the response functions associated with the longitudinal and transverse components of the (space-like) neutral current are largest and that a significant portion ($\simeq 30$ %) of the calculated strength is due to...

Topics: High Energy Physics - Phenomenology, Nuclear Experiment, Nuclear Theory

Source: http://arxiv.org/abs/1401.2605

27
27

Sep 18, 2013
09/13

by
L. E. Marcucci; M. Viviani; R. Schiavilla; A. Kievsky; S. Rosati

texts

######
eye 27

######
favorite 0

######
comment 0

Different models for conserved two- and three-body electromagnetic currents are constructed from two- and three-nucleon interactions, using either meson-exchange mechanisms or minimal substitution in the momentum dependence of these interactions. The connection between these two different schemes is elucidated. A number of low-energy electronuclear observables, including (i) $np$ radiative capture at thermal neutron energies and deuteron photodisintegration at low energies, (ii) $nd$ and $pd$...

Source: http://arxiv.org/abs/nucl-th/0502048v1

26
26

Sep 19, 2013
09/13

by
M. Viviani; A. Kievsky; L. E. Marcucci; S. Rosati; R. Schiavilla

texts

######
eye 26

######
favorite 0

######
comment 0

The present work reports results for: pd radiative capture observables measured at center-of-mass (c.m.) energies in the range 0--100 keV and at 2 MeV by the TUNL and Wisconsin groups, respectively; contributions to the Gerasimov-Drell-Hearn (GDH) integral in 3He from the two- up to the three-body breakup thresholds, compared to experimental determinations by the TUNL group in this threshold region; longitudinal, transverse, and interference response functions measured in inclusive polarized...

Source: http://arxiv.org/abs/nucl-th/9911051v1