V. S. Timóteo

Recursive renormalization of the singlet one-pion-exchange plus point-like interactions

Abstract The subtracted kernel approach is shown to be a powerful method to be implemented recursively in scattering equations with regular plus point-like interactions. The advantages of the method allows one to recursively renormalize the potentials, with higher derivatives of the Dirac-delta, improving previous results. The applicability of the method is verified in the calculation of the S 0 1 nucleon–nucleon phase-shifts, when considering a potential with one-pion-exchange plus a contact interaction and its derivatives. The S 0 1 renormalization parameters are fitted to the data. The method can in principle be extended to any derivative order of the contact interaction, to higher partial waves and to coupled channels.

Symmetries of the similarity renormalization group for nuclear forces

We review the role played by long-distance symmetries within the context of the similarity renormalization group approach. This is based on phase-shift-preserving continuous unitary transformations that evolve Hamiltonians with a cutoff on energy differences. We find that there is a similarity cutoff of 3/fm for which almost perfect fulfillment of Wigner SU(4) symmetry is found at the two body level. This suggests to look for similar symmetry patterns for three- and four-body forces. We also analyze the impact of potentials based on Chiral Perturbation Theory in Nuclear Structure calculations.

The few scales of nuclei and nuclear matter

The well-known correlations of low-energy three and four-nucleon observables with a typical three-nucleon scale (e.g., the Tjon line) is extended to light nuclei and nuclear matter. Evidence for the scaling between light nuclei binding energies and the triton one are pointed out. We argue that the saturation energy and density of nuclear matter are correlated to the triton binding energy. The available systematic nuclear matter calculations indicate a possible band structure representing these correlations.

Implicit vs explicit renormalization and effective interactions

Abstract Effective interactions can be obtained from a renormalization group analysis in two complementary ways. One can either explicitly integrate out higher energy modes or impose given conditions at low energies for a cut-off theory. While the first method is numerically involved, the second one can be solved almost analytically. In both cases we compare the outcoming effective interactions for the two nucleon system as functions of the cut-off scale and find a strikingly wide energy region where both approaches overlap, corresponding to relevant scales in light nuclei Λ ≲ 200 MeV . This amounts to a great simplification in the determination of the effective interaction parameters.

Similarity renormalization group evolution of chiral effective nucleon–nucleon potentials in the subtracted kernel method approach

Abstract Methods based on Wilson’s renormalization group have been successfully applied in the context of nuclear physics to analyze the scale dependence of effective nucleon–nucleon ( NN ) potentials, as well as to consistently integrate out the high-momentum components of phenomenological high-precision NN potentials in order to derive phase-shift equivalent softer forms, the so called V low - k potentials. An alternative renormalization group approach that has been applied in this context is the similarity renormalization group (SRG), which is based on a series of continuous unitary transformations that evolve hamiltonians with a cutoff on energy differences. In this work we study the SRG evolution of a leading order (LO) chiral effective NN potential in the 1 S 0 channel derived within the framework of the subtracted kernel method (SKM), a renormalization scheme based on a subtracted scattering equation.

π 0 pole mass calculation in a strong magnetic field and lattice constraints

Abstract The π 0 neutral meson pole mass is calculated in a strongly magnetized medium using the SU(2) Nambu–Jona–Lasinio model within the random phase approximation (RPA) at zero temperature and zero baryonic density. We employ a magnetic field dependent coupling, G ( e B ) , fitted to reproduce lattice QCD results for the quark condensates. Divergent quantities are handled with a magnetic field independent regularization scheme in order to avoid unphysical oscillations. A comparison between the running and the fixed couplings reveals that the former produces results much closer to the predictions from recent lattice calculations. In particular, we find that the π 0 meson mass systematically decreases when the magnetic field increases while the scalar mass remains almost constant. We also investigate how the magnetic background influences other mesonic properties such as f π 0 and g π 0 q q .

Thermo-magnetic effects in quark matter: Nambu-Jona-Lasinio model constrained by lattice QCD

Abstract.The phenomenon of inverse magnetic catalysis of chiral symmetry in QCD predicted by lattice simulations can be reproduced within the Nambu-Jona-Lasinio model if the coupling G of the model decreases with the strength B of the magnetic field and temperature T. The thermo-magnetic dependence of G(B, T) is obtained by fitting recent lattice QCD predictions for the chiral transition order parameter. Different thermodynamic quantities of magnetized quark matter evaluated with G(B, T) are compared with the ones obtained at constant coupling, G. The model with G(B, T) predicts a more dramatic chiral transition as the field intensity increases. In addition, the pressure and magnetization always increase with B for a given temperature. Being parametrized by four magnetic-field-dependent coefficients and having a rather simple exponential thermal dependence our accurate ansatz for the coupling constant can be easily implemented to improve typical model applications to magnetized quark matter.

Power counting and renormalization group invariance in the subtracted kernel method for the two-nucleon system

We apply the subtracted kernel method (SKM), a renormalization approach based on recursive multiple subtractions performed in the kernel of the scattering equation, to the chiral nucleon–nucleon (NN) interactions up to next-to-next-to-leading-order. We evaluate the phase-shifts in the 1S0 channel at each order in Weinberg’s power counting scheme and in a modified power counting scheme which yields a systematic power-law improvement. We also explicitly demonstrate that the SKM procedure is renormalization group invariant under the change of the subtraction scale through a non-relativistic Callan–Symanzik flow equation for the evolution of the renormalized NN interactions.

Nucleon-nucleon scattering within a multiple subtractive renormalization approach

We present a methodology to renormalize the nucleon-nucleon interaction in momentum space, using a recursive multiple subtraction approach that prescinds from a cutoff regularization, to construct the kernel of the scattering equation. The subtracted scattering equation is solved with the next-leading-order and nextto-next-leading-order interactions. The results are presented for all partial waves up to j = 2, fitted to lowenergy experimental data. In this renormalization group invariant approach, the subtraction energy emerges as a renormalization scale and the momentum associated with it comes to be about the QCD scale (� QCD), irrespectively to the partial wave. I. INTRODUCTION The nucleon-nucleon (NN) interaction in leading order corresponds to the one-pion-exchange potential (OPEP) plus aD iracδ, when considering an effective field theory (EFT) of nuclear forces based on a chiral expansion of the effective Lagrangian. This procedure was suggested by Weinberg [1], with a recipe to infer the values of the strength of the Dirac-δ interaction in the 1 S0 and 3 S1 channels from the singlet and triplet scattering lengths, respectively. Therefore, the singlet and triplet scattering lengths make it possible to fit the renormalized strengths of the contact interactions. This effective potential should be valid for momenta well below some typical momentum scale considered in QCD, such as the

Simulation inspired model for energy consumption in 3G always-on mobiles

Mobile devices that are permanently connected to IP networks are prone to have higher energy consumptions because unsolicited packets also force the device to move to a state where the consumption is higher. We consider a simplified model for the energy consumption based on the average consumptions in the different states and the time the device stays in each state. We perform discrete event simulations to obtain the energy consumption for different traffic scenarios and the simulation results are then fitted with simple models. We find that they give a relatively good description of the energy consumption behavior as a function of the T2 timer. Also, our results are consistent with measurements of the energy consumption for a mobile device connected to 3G networks with high or low data traffic profile.