Renormalization of chiral nuclear forces with multiple subtractions in peripheral channels

We analyse the renormalization of the of two-nucleon interaction with multiple subtractions in peripheral waves considering two chiral forces at N3LO. Phase shifts at low energies are then computed with several subtraction points below \mu = 10 / fm. We show that for most peripheral waves the phase shifts have nearly no dependence on the renormalization scale. In two cases the phase shifts converge slowly as the renormalization scale approaches \mu = 1 / fm and in one case the phase shifts presented oscillations with respect to the subtraction point \mu.Comment: 21 pages, 12 figures, to appear in the special issue "Few-Body Systems in High Energy Physics" (AHEP

Phase transition of the nucleon-antinucleon plasma at different ratios

We investigate phase transitions for the Walecka model at very high temperatures. As is well known, depending on the parametrization of this model and for the particular case of a zero chemical potential ($\mu$), a first order phase transition is possible \cite{theis}. We investigate this model for the case in which $\mu \ne 0$. It turns out that, in this situation, phases with different values of antinucleon-nucleon ratios and net baryon densities may coexist. We present the temperature versus antinucleon-nucleon ratio as well as the temperature versus the net baryon density for the coexistence region. The temperature versus chemical potential phase diagram is also presented.Comment: 5 pages, 8 figure

On the q-deformation of the NJL model

Using a q-deformed fermionic algebra we perform explicitly a deformation of the Nambu-Jona-Lasinio (NJL) Hamiltonian. In the Bogoliubov-Valatin approach we obtain the deformed version of the functional for the total energy, which is minimized to obtain the corresponding gap equation. The breaking of chiral symmetry and its restoration in the limit $q \to 0$ are then discussed.Comment: 5 eps figure

Block-diagonal similarity renormalization group and effective nucleon-nucleon interactions

We apply the block-diagonal similarity renormalization group to a simple toy-model for the nucleon-nucleon (N N) interaction in the S-1(0) channel, aiming to analyze the complementarity between the explicit and the implicit renormalization approaches in nuclear physics. By explicit renormalization we mean the methods based on the wilsonian renormalization group in which high-energy modes above a given cutoff scale are integrated out while their effects are replaced by scale dependent effective interactions consistently generated in the process. We call implicit renormalization the usual procedure of cutoff effective theories in which the high-energy modes above the cutoff scale are simply removed and their effects are included through parametrized cutoff dependent counterterms whose strengths are fixed by fitting low-energy data. We compare the effective interactions obtained in both schemes and find a wide range of cutoff scales where they overlap. We further analyze the role played by the one-pion exchange (OPE) considering a delta-shell plus OPE representation for the N N interaction.We apply the block-diagonal similarity renormalization group to a simple toy-model for the nucleon-nucleon (NN) interaction in the 1 S 0 channel, aiming to analyze the complementarity between the explicit and the implicit renormalization approaches in nuc706FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informação13th International Workshop on Hadron PhysicsE.R.A. would like to thank the Spanish DGI (Grant FIS2011-24149) and Junta de Andalucia (Grant FQM225). S.S. is partially supported by FAPESP and V.S.T. thanks FAEPEX, FAPESP and CNPq for financial support

Nucleon-nucleon scattering within a multiple subtractive renormalization approach

A methodology to renormalize the nucleon-nucleon interaction, using a recursive multiple subtraction approach to construct the kernel of the scattering equation, is presented. We solve the subtracted scattering equation with the next-leading-order (NLO) and next-to-next-leading-order (NNLO) interactions. The results are presented for all partial waves up to $j=2$, fitted to low-energy experimental data. In our renormalizaton group invariant method, when introducing the NLO and NNLO interactions, the subtraction energy emerges as a renormalization scale and the momentum associated with it comes to be about the QCD scale ($\Lambda_{QCD}$), irrespectively to the partial wave.Comment: Final versio

Running of the contact interactions in chiral N3LO potentials from subtractive renormalization

In this work a subtracted kernel renormalization procedure (SKM) is applied to the chiral NN potential up to next-to-next-to-next-to-leading-order ((NLO)-L-3) to obtain the running of the renormalized contact strengths with the subtraction scale mu and the phase shifts for all uncoupled waves with contact interaction (S, P, D). We use two potentials constructed within the framework of Weinberg's approach to ChEFT, which provide a very accurate description of NN scattering data below laboratory energies E similar to 350 MeV, namely Epelbaum, Glockle and Meissner (N3LO-EGM) and Entem and Machleidt (N3LO-EM). For both potentials, we consider a large cutoff (30 fm(-1)) and analyze the phases and the running of the contact strengths with the subtraction point mu by making a fit of the K-matrix with five subtractions to the K-matrix from the Nijmegen II potential at low energies (E <= 20 MeV).In this work a subtracted kernel renormalization procedure (SKM) is applied to the chiral NN potential up to next-to-next-to-next-to-leading-order (N 3 LO) to obtain the running of the renormalized contact strengths with the subtraction scale μ and the ph630FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informação37th Brazilian Meeting on Nuclear PhysicsS.S. is partially supported by FAPESP and V.S.T. would like to thank FAEPEX, FAPESP and CNPq for financial support

Nonlinear Klein-Gordon equation and the Bose-Einstein condensation

El interés por la ecuación de Klein-Gordon con diferentes potenciales ha aumentado en los últimos años debido a su posible aplicaciones en Cosmología, Física de Hadrones y Física de Altas Energías. En este trabajo, investigamos las soluciones de la ecuación de Klein–Ecuación para bosones bajo la influencia de un potencial externo utilizando el método de Feshbach-Villars. Presentamos resultados detallados en dos casos: el potencial de Coulomb y el potencial armónico. Para el segundo caso, estudiamos los efectos de la auto-interacción de partículas dentro de una aproximación de de campo medio. Mostramos que nuestros resultados convergen suavemente a la solución de la ecuación de Schrödinger para los mismos sistemas a medida que disminuyen los efectos relativistas. En inglés: The interest in the Klein–Gordon equation with different potentials has increased in recent years due to its possible applications in Cosmology, Hadron Physics and High-Energy Physics. In this work, we investigate the solutions of the Klein–Gordon equation for bosons under the influence of an external potential by using the Feshbach–Villars method. We present detailed results for two cases: the Coulombic potential and the harmonic potential. For the latter case, we studied the effects of self-interacting particles by adopting a mean-field approach. We show that our results converge smoothly to the solution of the Schrödinger equation for the same systems as the relativistic effects diminish.FQM-225CNPq-Brazil 304244/2018-0Consejería de ConocimientoConselho Nacional de Desenvolvimento Científico e TecnológicoFAEPEX 2019/010889-1, 3258/19Investigación y Universidad of the Junta de AndalucíaJunta de Andalucía-Consejería de Economía y Conocimiento 2014-2020 Operational ProgramFundação de Amparo à Pesquisa do Estado de São Paulo 2021/12954-5Conselho Nacional de Desenvolvimento Científico e Tecnológico 306615/2018-5European Regional Development Fund RYC-2016-20678, SOMM17/6105/UGRJunta de Andalucía A-FQM-178-UGR18, FQM-225Instituto Nacional de Ciência e Tecnologia: Física Nuclear e Aplicações 2016/17612-7, 464 898/2014-5Consejería de Conocimiento, Investigación y Universidad, Junta de Andalucí

Impact of a magnetic field on the thermodynamics of magnetized quark matter

We investigate the effect of a magnetic field on the thermodynamics of magnetized quark matter at finite temperature. By using the Nambu Jona-Lasino (NJL) model, we show that the lattice results for the quark consensate can be reproduced when the coupling constant G of the model decreases with the magnetic field and the temperature. Our results show that thermodynamic quantities and quark condensates are very sensitive to the dependence of G with the temperature, even in the absence of a magnetic field.We investigate the effect of a magnetic field on the thermodynamics of magnetized quark matter at finite temperature. By using the Nambu Jona-Lasino (NJL) model, we show that the lattice results for the quark consensate can be reproduced when the coupling706FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESC - FUNDAÇÃO DE AMPARO À PESQUISA E INOVAÇÃO DO ESTADO DE SANTA CATARINACNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçãosem informação13th International Workshop on Hadron PhysicsWe thank G. Endrodi for helpful discussions and for providing the lattice data for u and d quark condensates. We also thank FAEPEX, FAPESP, FAPESC and CNPq for financial support

Symmetries of the Similarity Renormalization Group for Nuclear Forces

We analyze the role played by Long Distance Symmetries within the context of the Similarity Renormalization Group (SRG) approach, which is based on phase-shift preserving continuous unitary transformations that evolve hamiltonians with a cutoff on energy differences. We find that there is a SRG cutoff for which almost perfect fulfillment of Wigner symmetry is found. We discuss the possible consequences of such finding.Comment: 16 pages, 6 figures, to appear in Physical Review

Unitary neutron matter in the on-shell limit

37th Brazilian Meeting on Nuclear Physics. Sao Paulo (Brazil), 8-12 September 2014.We compute the Bertsch parameter for neutron matter by using nucleon-nucleon interactions that are fully diagonal in momentum space. We analyze the on-shell limit with the similarity renormalization group and compare the results for a simple separable toy model to realistic calculations with high precision NN potentials.E.R.A. would like to thank the Spanish DGI (Grant FIS2011-24149) and Junta de Andalucia (Grant FQM225) for support. S.S. is partially supported by FAPESP and V.S.T. thanks FAEPEX, FAPESP and CNPq for financial support