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(9) Production(s) de l'année 2021


All order resummed leading and nexttoleading soft modes of dense QCD pressure
Auteur(s): Fernandez L., Kneur J.L.
(Document sans référence bibliographique) Texte intégral en Openaccess :
Ref HAL: hal03347966_v1
Ref Arxiv: 2109.02410
Ref INSPIRE: 1917540
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: The cold and dense QCD equation of state (EoS) at high baryon chemical potential $\mu_B$ involves at order $\alpha^2_S$ an allloop summation of the soft mode $m_E\sim \alpha_S^{1/2} \mu_B$ contributions. Recently the complete soft contributions at order $\alpha^3_S$ were calculated, using the hard thermal loop (HTL) formalism. By identifying {\em massive} renormalization group (RG) properties within HTL, we resum to all orders $\alpha_S^p, p\ge 3$ the leading and nexttoleading logarithmic soft contributions. We obtain compact analytical expressions, that show sizeable deviations from the stateofthe art results, and noticeably reduced residual scale dependence. Our results should help to reduce uncertainties in extending the EoS in the intermediate $\mu_B$ regime, relevant in particular for the phenomenology of neutron stars.



Renormalization group optimized $\lambda \phi^4$ pressure at nexttonexttoleading order
Auteur(s): Fernandez L., Kneur J.L.
(Document sans référence bibliographique) Texte intégral en Openaccess :
Ref HAL: hal03319381_v1
Ref Arxiv: 2107.13328
Ref INSPIRE: 1894553
Ref. & Cit.: NASA ADS
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Résumé: We investigate the renormalization group optimized perturbation theory (RGOPT) at the nexttonexttoleading order (NNLO) for the thermal scalar field theory. From comparing three thus available successive RGOPT orders we illustrate the efficient resummation and very good apparent convergence properties of the method. In particular the remnant renormalization scale dependence of thermodynamical quantities is drastically improved as compared to both standard perturbative expansions and other related resummation methods, such as the screened perturbation theory. Our present results thus constitute a useful first NNLO illustration in view of NNLO applications of this approach to the more involved thermal QCD.



Coulomb branch of N=4 SYM and dilatonic scions in supergravity
Auteur(s): Elander D., Piai Maurizio, Roughley John
(Article) Publié:
Phys.rev.d, vol. 104 p.046003 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03186214_v1
Ref Arxiv: 2103.06721
Ref INSPIRE: 1851112
DOI: 10.1103/PhysRevD.104.046003
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: We find a parametrically light dilaton in special confining theories in three dimensions. Their duals form what we call a scion of solutions to the supergravity associated with the large$N$ limit of the Coulomb branch of the $\mathcal{N}=4$ SuperYangMills theory. The supergravity description contains one scalar with bulk mass that saturates the BreitenlohnerFreedman unitarity bound. The new solutions are defined within supergravity, they break supersymmetry and scale invariance, and one dimension is compactified on a shrinking circle, yet they are completely regular. An approximate dilaton appears in the spectrum of background fluctuations (or composite states in the confining theory), and becomes parametrically light along a metastable portion of the scion of new supergravity solutions, in close proximity of a tachyonic instability. A firstorder phase transition separates stable backgrounds, for which the approximate dilaton is not parametrically light, from metastable and unstable backgrounds, for which the dilaton becomes parametrically light, and eventually tachyonic.



Renormalization group improved pressure for hot and dense quark matter
Auteur(s): Kneur J.L., Pinto Marcus Benghi, Restrepo Tulio E.
(Article) Publié:
Physical Review D, vol. 104 p.034003 (2021)
Texte intégral en Openaccess :
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Ref Arxiv: 2101.08240
Ref INSPIRE: 1842071
DOI: 10.1103/PhysRevD.104.034003
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: We apply the renormalization group optimized perturbation theory (RGOPT) to evaluate the quark contribution to the QCD pressure at finite temperatures and baryonic densities, at nexttoleading order (NLO). Our results are compared to NLO and stateoftheart higher orders of standard perturbative QCD (pQCD) and hard thermal loop perturbation theory (HTLpt). The RGOPT provides an all order resummed pressure in a welldefined approximation, exhibiting a drastically better remnant renormalization scale dependence than pQCD, thanks to builtin renormalization group invariance consistency. At NLO, upon simply adding to the RGOPTresummed quark contributions the purely perturbative NLO glue contribution, our results show a remarkable agreement with ab initio lattice simulation data for temperatures $0.25\lesssim T\lesssim 1\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{GeV}$, with a remnant scale dependence drastically reduced as compared to HTLpt.



QCD pressure: Renormalization group optimized perturbation theory confronts lattice
Auteur(s): Kneur J.L., Pinto Marcus Benghi, Restrepo Tulio E.
(Article) Publié:
Physical Review D, vol. 104 p.L031502 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03115871_v1
Ref Arxiv: 2101.02124
Ref INSPIRE: 1839547
DOI: 10.1103/PhysRevD.104.L031502
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: The quark contribution to the QCD pressure, ${P}_{q}$, is evaluated up to nexttoleading order (NLO) within the renormalization group optimized perturbation theory (RGOPT) resummation approach. To evaluate the complete QCD pressure we simply add the perturbative NLO contribution from massless gluons to the resummed ${P}_{q}$. Despite this unsophisticated approximation our results for $P={P}_{q}+{P}_{g}$ at the central scale $M\sim 2\pi T$ show a remarkable agreement with lattice predictions for $0.25\lesssim T\lesssim 1\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{GeV}$. We also show that by being imbued with RG properties, the RGOPT produces a drastic reduction of the embarrassing remnant scale dependence that plagues both standard thermal perturbative QCD and hard thermal loop perturbation theory applications.



Vacuum stability conditions for Higgs potentials with SU(2)(L) triplets
Auteur(s): Moultaka G., Peyranère Michel
(Article) Publié:
Physical Review D, vol. 103 p.115006 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03087658_v1
Ref Arxiv: 2012.13947
DOI: 10.1103/PhysRevD.103.115006
WoS: WOS:000661786800005
Ref. & Cit.: NASA ADS
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Résumé: Treelevel dynamical stability of scalar field potentials in renormalizable theories can in principle be expressed in terms of positivity conditions on quartic polynomial structures. However, these conditions cannot always be cast in a fully analytical resolved form, involving only the couplings and being valid for all field directions. In this paper we consider such forms in three physically motivated models involving SU (2) triplet scalar fields: the TypeII seesaw model, the GeorgiMachacek model, and a generalized twotriplet model. A detailed analysis of the latter model allows to establish the full set of necessary and sufficient boundedness from below conditions. These can serve as a guide, together with unitarity and vacuum structure constraints, for consistent phenomenological (treelevel) studies. They also provide a seed for improved looplevel conditions, and encompass in particular the leading ones for the more specific GeorgiMachacek case. Incidentally, we present complete proofs of various properties and also derive general positivity conditions on quartic polynomials that are equivalent but much simpler than the ones used in the literature.



Light dilaton in a metastable vacuum
Auteur(s): Elander D., Piai Maurizio, Roughley John
(Article) Publié:
Physical Review D, vol. 103 p.046009 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03047633_v1
Ref Arxiv: 2011.07049
Ref INSPIRE: 1830179
DOI: 10.1103/PhysRevD.103.046009
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: We identify a parametrically light dilaton by studying the perturbations of metastable vacua along a branch of regular supergravity backgrounds that are dual to fourdimensional confining field theories. The branch includes also stable and unstable solutions. The former encompass, as a special case, the geometry proposed by Witten as a holographic model of confinement. The latter approach a supersymmetric solution, by enhancing a condensate in the dual field theory. A phase transition separates the space of stable backgrounds from the metastable ones. In proximity of the phase transition, one of the lightest scalar states inherits some of the properties of the dilaton, despite not being particularly light.
