Lygia Martins Costa

Gomes, Ana Lúcia de Abreu; Carrijo, Elizângela

doi:10.26512/museologia.v1i1.12645

Cited by 3 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…where Z ψ (g) is the wavefunction renormalization constant that can be found in Refs. [102,103]. Notice that the structure of the four-fermion operators and their couplings in H Th are different from that in the action of Eq.…”

Section: A the Hamiltonian Operator At Quantum Level And The Staggermentioning

confidence: 95%

“…In Refs. [103,137] the scaling dimension of this operator was studied using the operator product expansion (OPE), and was found to increase with decreasing coupling strength, g. It is allowed to be larger than two when g is small enough. In this regard, our numerical investigation shows the same feature as that from these previous studies.…”

Section: B Implication For Scaling Behaviour and The Continuum Limitmentioning

confidence: 99%

See 1 more Smart Citation

Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states

et al. 2019

View full text Add to dashboard Cite

Employing matrix product states as an ansatz, we study the non-thermal phase structure of the (1+1)-dimensional massive Thirring model in the sector of vanishing total fermion number with staggered regularization. In this paper, details of the implementation for this project are described. To depict the phase diagram of the model, we examine the entanglement entropy, the fermion bilinear condensate and two types of correlation functions. Our investigation shows the existence of two phases, with one of them being critical and the other gapped. An interesting feature of the phase structure is that the theory with non-zero fermion mass can be conformal. We also find clear numerical evidence that these phases are separated by a transition of the Berezinskii-Kosterlitz-Thouless type. Results presented in this paper establish the possibility of using the matrix product states for probing this type of phase transition in quantum field theories. They can provide information for further exploration of scaling behaviour, and serve as an important ingredient for controlling the continuum extrapolation of the model. arXiv:1908.04536v2 [hep-lat] 21 Aug 2019 1 A different TN approach, the tensor renormalization group method, in which one works with the partition function, has also been implemented for the investigation of several quantum field theories [63-71] and the formulation of quantum gravity [72].

show abstract

Section: A the Hamiltonian Operator At Quantum Level And The Staggermentioning

confidence: 95%

Section: B Implication For Scaling Behaviour and The Continuum Limitmentioning

confidence: 99%

Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Theorem 1 (Caeiro et al [8]). Under a second-order framework, that is, assuming that condition (8) holds, with k an intermediate sequence, as in ( 5), the WTC-estimator θGG p (k), in (17), has an asymptotic distributional representation of the type,…”

Section: Asymptotic Behavior Of the Wtc-estimators Under Studymentioning

confidence: 99%

“…In our study, we will focus on two particular classes of GM's based on the log-excesses, in (9), and on the relative excesses, in (10). The first GM considered is the power mean of exponent p of the log-excesses, PM p , introduced in Gomes and Martins [17], also considered in Segers [18], and further studied in Gomes and Martins [19]. This class of EVI-estimators is defined by…”

Section: Semiparametric Evi-and Wtc-estimatorsmentioning

confidence: 99%

“…In our study, we will focus on two particular classes of GM's based on the log‐excesses, in (), and on the relative excesses, in (). The first GM considered is the power mean of exponent

p

of the log‐excesses, PM

{}_p

, introduced in Gomes and Martins [17], also considered in Segers [18], and further studied in Gomes and Martins [19]. This class of EVI‐estimators is defined by

{\mathrm{PM}}_{k,n,p}\equiv {\mathrm{PM}}_p(k):&amp;amp;#x0003D; {\left(\frac{M_{k,n}&amp;amp;#x0005E;{(p)}}{\Gamma \left(p&amp;amp;#x0002B;1\right)}\right)}&amp;amp;#x0005E;{1/p},\kern0.30em \mathrm{for}\kern0.20em p&amp;gt;-1,\kern0.30em p\ne 0

with

{\mathrm{PM}}_1(k)\equiv \mathrm{H}(k)

, in (),

\Gamma

denoting the complete Gamma function and

M_{n, k}^{false(p false)} : = \frac{1}{k} \sum_{i = 1}^{k} {((), \ln X_{n - i + 1 : n} - \ln X_{n - k : n})}^{p} = \frac{1}{k} \sum_{i = 1}^{k} V_{i k}^{p} ...

…”

Section: Introduction and Scope Of The Articlementioning

confidence: 99%

See 1 more Smart Citation

Improvements in the estimation of the Weibull tail coefficient: A comparative study

Henriques‐Rodrigues,

Caeiro,

Gomes

2024

Math Methods in App Sciences

View full text Add to dashboard Cite

The Weibull tail‐coefficient (WTC) plays a crucial role in extreme value statistics when dealing with Weibull‐type tails. Several distributions, such as normal, Gamma, Weibull, and logistic distributions, exhibit this type of tail behavior. The WTC, denoted by , is a parameter in a right‐tail function of the form , where represents a regularly varying cumulative hazard function with an index of regular variation equal to 1/ . The commonly used WTC‐estimators in literature are often defined as functions of the log‐excesses, making them closely related to estimators of the extreme value index (EVI) for Pareto‐type tails. For a positive EVI, the classical estimator is the Hill estimator. Generalized means have been successfully employed in estimating the EVI, leading to reduction of bias and of root mean square error for appropriate threshold values. In this study, we propose and investigate new classes of WTC‐estimators based on power of the log‐excesses within a second‐order framework. The performance of these new estimators is evaluated through a large‐scale Monte Carlo simulation study, comparing them with existing WTC‐estimators available in the literature.

show abstract

The PORTSEA (Portuguese School of Extremes and Applications) and a few personal scientific achievements

Gomes

2024

Communications in Mathematics

View full text Add to dashboard Cite

The Portuguese School of Extremes and Applications is nowadays well recognised by the international scientific community, and in my opinion, the organisation of a NATO Advanced Study Institute on Statistical Extremes and Applications, which took place at Vimeiro in the summer of 1983, was a landmark for the international recognition of the group. The dynamic of publication has been very high and the topics under investigation in the area of Extremes have been quite diverse. In this article, attention will be paid essentially to some of the scientific achievements of the author in this field.

show abstract

Lygia Martins Costa

Cited by 3 publications

References 0 publications

Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states

Phase structure of the (1+1)-dimensional massive Thirring model from matrix product states

Improvements in the estimation of the Weibull tail coefficient: A comparative study

The PORTSEA (Portuguese School of Extremes and Applications) and a few personal scientific achievements

Contact Info

Product

Resources

About