Mon·Jan 21, 2019Monday·January 21, 2019

1. 01*

   Approaching robust EFT limits for CP-violation in the Higgs sector

   Christoph Englert🇬🇧 · Peter Galler🇬🇧 · Andrew Pilkington🇬🇧 · Michael Spannowsky🇬🇧

   Constraining CP-violating interactions in effective field theory (EFT) of dimension six faces two challenges. Firstly, degeneracies in the multi-dimensional space of Wilson coefficients have to be lifted. Secondly, quadratic contributions of CP-odd dimension six operators are difficult to disentangle from squared contributions of CP-even dimension six operators and from linear contributions of dimension eight operators. Both of these problems are present when new sources of CP-violation are present in the interactions between the Higgs boson and heavy strongly-interacting fermions. We show that degeneracies in the Wilson coefficients can be removed by combining measurements of Higgs-plus-two-jet production via gluon fusion with measurements of top-pair associated Higgs production. In addition, we demonstrate that the sensitivity of the analysis can be improved by exploiting the top-quark threshold in the gluon fusion process. Finally, we substantiate a perturbative argument about the validity of EFT by comparing the quadratic and linear contributions from CP-odd dimension six operators and use this to show explicitly that high statistics measurements at future colliders enable the extraction of perturbatively robust constraints on the associated Wilson coefficients.

   hep-phhep-exPRD(2019)·34 citations
2. 02*

   Dipion light-cone distribution amplitudes and $B\to \pi \pi$ form factors

   Shan Cheng🇨🇳

   We suggest to update the expansion coefficients of 2$\pi$DAs with the distribution amplitudes of light mesons evaluated from lattice QCD, with which we revisit ${\overline{B}}^0\to {\pi }^{+}{\pi }^0$ transition form factors from light-cone sum rules approach and extend the predictions from the threshold of dipion invariant mass to high energies with including the resonance intervals. We also derive $B^{-}\to {\pi }^0{\pi }^0$ transition form factors with the isoscalar dipion final state, serving as the supplement to the isovector ones to complete the set of light-cone sum rules prediction of $B\to \pi \pi$ form factors. Our numerics shows that the lowest resonance gives the dominant contribution to $P-$wave form factors, while the resonance contribution in $S-$wave is not so salient.

   hep-phPRD(2019)·12 citations
3. 03*

   Strange and charmed baryon productions with an instanton interaction

   Sang-In Shim🇯🇵 · Atsushi Hosaka🇯🇵 · Hyun-Chul Kim🇰🇷

   We study strange and charmed baryon productions, $\pi +p\to K(D)+Y(Y_c)$, where $Y(Y_c)$ is a strange(charmed) baryon of a ground or an excited state. We propose a new production mechanism where two quarks in the baryon participate in the reaction (two-quark process), which enables excitation of both $\lambda$- and $\rho$-modes of the baryons. To deal with the two-quark process, we consider the 't Hooft six-quark interaction from the instanton model. We study production rates in relation with the structure of charmed baryons for the forward angle scattering.

   hep-phhep-exJPS Conf.Proc.(2019)·1 citation
4. 04*

   Neutrino Oscillations and Leptogenesis

   Anupam Yadav🇮🇳 · Sabeeha Naaz🇮🇳 · Jyotsna Singh🇮🇳 · R.B. Singh🇮🇳

   The symmetry breaking of left right symmetric model around few TeV range permits the existence of massive right handed neutrinos or gauge bosons. In this work the decay of lightest right handed neutrinos in a class of minimal left right symmetric model is analysed for the generation of adequate lepton asymmetry. An analytical expression for the lepton asymmetry is developed. In an attempt to achieve the required baryogenesis, we have imposed certain constrains on the parameter space corresponding to low energy neutrino oscillation parameters (especially {\theta} 13 ) and the three phases ( CP, majorana and higher energy phase).

   hep-ph0 citations
5. 05*

   Decay of I-ball/Oscillon in Classical Field Theory

   Masahiro Ibe🇯🇵 · Masahiro Kawasaki🇯🇵 · Wakutaka Nakano🇯🇵 · Eisuke Sonomoto🇯🇵

   I-balls/oscillons are long-lived and spatially localized solutions of real scalar fields. They are produced in various contexts of the early universe in, such as, the inflaton evolution and the axion evolution. However, their decay process has long been unclear. In this paper, we derive an analytic formula of the decay rate of the I-balls/oscillons within the classical field theory. In our approach, we calculate the Poynting vector of the perturbation around the I-ball/oscillon profile by solving a relativistic field equation, with which the decay rate of the I-ball/oscillon is obtained. We also perform a classical lattice simulation and confirm the validity of our analytical formula of the decay rate numerically.

   hep-phastro-ph.COJHEP(2019)·53 citations
6. 06*

   Sign of CP Violating Phase in Quarks and Leptons

   Yusuke Shimizu🇯🇵 · Kenta Takagi🇯🇵 · Shunya Takahashi🇯🇵 · Morimitsu Tanimoto🇯🇵

   We discuss the relation between the CP violation of the quark mixing and that of the lepton mixing by investigating a CP violating observable, the Jarlskog invariant, as well as the CP violating Dirac phase. The down-type quark mass matrix with three zeros is given in terms of the minimal number of parameters, while the up-type quark mass matrix is diagonal. These quark mass matrices leading to the successful CKM mixing angles and CP violation are embedded in both the Pati--Salam and SU(5) models. The leptonic Jarlskog invariant $J_{CP}^l$ (as well as CP violating Dirac phase) is examined for two cases: the neutrino mass matrix is diagonal or non-diagonal, where no additional CP violating phase is introduced apart from the Majorana phases. In the case of the diagonal neutrino mass matrix, the favorable sign of the leptonic CP violation is obtained, however, the magnitude of $J_{CP}^l$ is at most $\mathcal{O}(10^{-4})$, which is too small compared with the expected value from the observation $-0.02$. In the case of the non-diagonal neutrino mass matrix where the tri-bimaximal mixing pattern is taken, we obtain the successful $J_{CP}^l$ up to its sign.

   hep-phJHEP(2019)·4 citations
7. 07*

   Two-loop evolution equations for flavor-singlet light-ray operators

   V. M. Braun🇩🇪 · A. N. Manashov🇩🇪 · S. Moch🇩🇪 · M. Strohmaier🇩🇪

   QCD in non-integer $d=4-2ϵ$ space-time dimensions enjoys conformal invariance at the special fine-tuned value of the coupling. Counterterms for composite operators in minimal subtraction schemes do not depend on $ϵ$ by construction, and therefore the renormalization group equations for composite operators in physical (integer) dimensions inherit conformal symmetry. This observation can be used to restore the complete evolution kernels that take into account mixing with the operators containing total derivatives from their eigenvalues (anomalous dimensions). Using this approach we calculate the two-loop (NLO) evolution kernels for the leading twist flavor-singlet operators in the position space (light-ray operator) representation. As the main result of phenomenological relevance, in this way we are able to confirm the evolution equations of flavor-singlet generalized hadron parton distributions derived earlier by Belitsky and Müller using a different approach.

   hep-phhep-thJHEP(2019)·18 citations
8. 08*

   The Higgs Top Interface

   Roberto Franceschini🇮🇹

   After some recollection of the implications that top quark and Higgs boson properties determination have had on each other, we discuss recent and future expected progress in the study of the top-Higgs sector. In particular we discuss some results concerning new physics states interacting with the top-Higgs sector, the impact of measuring top-Higgs interactions accurately to determine the Higgs boson self interaction, the CP nature of the Higgs boson and possible detection of flavor violating interaction at levels comparable with the prediction of viable new physics models.

   hep-ph0 citations
9. 09*

   Nucleon resonance production in the $\gamma p\to p\eta \varphi$ reaction

   Jin-Quan Fan · Shao-Fei · Chen · Bo-Chao Liu

   In this work, we perform a study of nucleon resonance production in the $\gamma p\to p\eta \varphi$ reaction within an effective Lagrangian approach. In our model, we consider the excitation of the $N^{\ast }(1535)$, $N^{\ast }(1650)$, $N^{\ast }(1710)$ and $N^{\ast }(1720)$ in the intermediate state and the background term. We find that this reaction is dominated by the excitation of the $N^{\ast }(1535)$ in the near threshold region. Especially, we study the possible role of the scalar meson exchange in this reaction. It is found that the $f_0(980)$ exchange may give a significant contribution and the parity asymmetry can be used to identify its role in this reaction.

   hep-phnucl-thPRC(2019)·11 citations
10. 10*

    Quark mass effects in the thermodynamical properties of an extended (P)NJL model

    J. Moreira🇵🇹 · J. Morais🇵🇹 · B. Hiller🇵🇹 · A. H. Blin🇵🇹 · A. A. Osipov🇷🇺

    We analyze the thermodynamical properties of a system of strongly interacting particles at vanishing quark chemical potential in the framework of a recently developed extension of the Polyakov-Nambu-Jona-Lasinio Model. In addition to eight quark interactions terms, non-canonical terms which explicitly break chiral symmetry up to the same order in a $1/N_c$ expansion ($N_c$ number of colors) are included. A recently proposed Polyakov potential is considered and the results are compared to lattice QCD data resulting in a favorable scenario for the recent model variants.

    hep-phJPS Conf.Proc.(2019)·0 citations
11. 11*

    Probing the photonic content of the proton using photon-induced dilepton production in $p+\text{Pb}$ collisions at the LHC

    Mateusz Dyndal🇩🇪 · Alexander Glazov🇩🇪 · Marta Luszczak🇵🇱 · Renat Sadykov🇷🇺

    We propose a new experimental method to probe the photon parton distribution function inside the proton (photon PDF) at LHC energies. The method is based on the measurement of dilepton production from the $\gamma p\to {\ell }^{+}{\ell }^{-}+X$ reaction in proton--lead collisions. These experimental conditions guarantee a clean environment, both in terms of reconstruction of the final state and in terms of possible background. We firstly calculate the cross sections for this process with collinear photon PDFs, where we identify optimal choice of the scale, in analogy to deep inelastic scattering kinematics. We then perform calculations including the transverse-momentum dependence of the probed photon. Finally we estimate rates of the process for the existing LHC data samples.

    hep-phhep-exPRD(2019)·8 citations
12. 12*

    Probing low energy scalar leptoquarks by the leptonic $W$ and $Z$ couplings

    Pere Arnan🇪🇸 · Damir Becirevic🇫🇷 · Federico Mescia🇪🇸 · Olcyr Sumensari🇮🇹

    We compute the generic one-loop contribution involving scalar leptoquarks (LQ) to the $W$ and $Z$ leptonic decay widths. In our computation we include for the first time the finite terms and the corrections due to the external momenta of the electroweak bosons, which is a step beyond the leading-logarithmic approximation considered in the literature so far. We show that the terms we include can be numerically quite significant. They amount to about $20\%$ for scalar LQ masses below $1.5$~TeV, as currently allowed by the direct searches at the LHC. To further illustrate the relevance of our results we revisit a model with two light scalar LQs, proposed to accommodate the $B$-physics anomalies. We show that the finite terms we computed can reduce the tension with the $Z$-pole data.

    hep-phJHEP(2019)·78 citations
13. 13*

    Very long-lived Stop NLSP in MSSM scenarios with Gravitino LSP

    J. Lorenzo Diaz-Cruz🇲🇽 · Bryan O. Larios🇲🇽

    We present the calculation of the stop ($\tilde{t}$) lifetime that results from its decay into gravitinos (${\tilde{\Psi }}^{\mu }$) in the final state, namely $\tilde{t}\to {\tilde{\Psi }}^{\mu }+X$, where $X=t,bW,bl{\nu }_l$ for the two-, three- and four-body decay modes. The full calculation is obtained using the Feynman rules for massive gravitino, which is compared with the results obtained employing the equivalence theorem, where the longitudinal component of the gravitino is replaced by the goldstino. The stop turns out to be very long-lived in these scenarios, with lifetimes of $\mathcal{O}$($10^8$s, $10^{14}$s, $10^{20}$s) for the corresponding 2-,3- and 4-body modes under consideration, and therefore all of them are safe from the big bang nucleosynthesis problem. However, the lifetime for the four body decay mode occurs during the epoch of galaxy formation. When the stop is produce at colliders, in these scenarios, it will hadronize and decay outside of the detector, even for the lowest values of stop lifetime.

    hep-ph3 citations
14. 14*

    The Jet Shape at NLL${}^{\prime }$

    Pedro Cal🇳🇱 · Felix Ringer🇺🇸 · Wouter J. Waalewijn🇳🇱

    The jet shape is the fraction of the jet energy within a cone $r$ centered on the jet axis. We calculate the jet shape distribution at next-to-leading logarithmic accuracy plus next-to-leading order (NLL${}^{\prime }$), accounting for logarithms of both the jet radius $R$ and the ratio $r/R$. This is the first phenomenological study that takes the recoil of the jet axis due to soft radiation into account, which is needed to reach this accuracy, but complicates the calculation of collinear radiation and requires the treatment of rapidity logarithms and non-global logarithms. We present numerical results, finding good agreement with ATLAS and CMS measurements of the jet shape in an inclusive jet sample, $pp\to \mathrm{jet}+X$, for different kinematic bins. The effect of the underlying event and hadronization are included using a simple one-parameter model, since they are not part of our perturbative calculation.

    hep-phhep-exnucl-thJHEP(2019)·37 citations
15. 15*

    $\Phi$ and $J/\Psi$ Mesons in Cold Nuclear Matter

    J. J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A. W. Thomas🇦🇺

    We present $\Phi$- and $J/\Psi$--nuclear bound state energies and absorption widths for some selected nuclei, using potentials in the local density approximation computed from an effective Lagrangian approach combined with the quark-meson coupling model. Our results suggest that these mesons should form bound states with all the nuclei considered provided that these mesons are produced in nearly recoilless kinematics.

    hep-phnucl-exnucl-thJPS Conf.Proc.(2019)·3 citations
16. 16*

    SU(8) Grand Unification from Composite Quarks and Leptons

    J.L. Chkareuli🇬🇪

    We consider the $L$-$R$ symmetric composite model for quarks and leptons where constituent preons possessing some local $SU(N{)}_{MF}$ metaflavor symmetry are bound by the chiral $SO(n{)}_L\times SO(n{)}_R$ gauge metacolor forces. The strengthening of the 't Hooft's anomaly matching condition, when the massless fermion composites are required to complete a single representation of the $SU(N{)}_{MF}$ rather than some set of its representations, allows to fix the number of basic metaflavors $N$. Particularly, just eight left-handed and eight right-handed preons and their composites preserving the global chiral symmetry $SU(8{)}_L\times SU(8{)}_R$ are turned out to underlie the physical world at small distances that uniquely identifies the local metaflavor symmetry $SU(8{)}_{MF}$ as its effective unified symmetry. We next show that the spontaneous $L$-$R$ symmetry violation caused by composite scalars reduces this initially vectorlike $SU(8{)}_{MF}$ theory down to the conventional $SU(5)$ GUT with an extra local family symmetry $SU(3{)}_F$ and three standard families of quarks and leptons. Though the tiny confinement scale for universal preons composing both quarks and leptons makes it impossible to directly confirm their composite nature, simultaneous emergence of several extra $SU(5)\times SU(3{)}_F$ multiplets of heavy composite fermions may help with a model verification. Generally, they may be located at scales from $O(100)$ $TeV$ up to the Planck mass scale depending on an interplay between the compositeness scale and scale of the family symmetry $SU(3{)}_F$. Some of them through a natural see-saw mechanism provide neutrino masses which, in contrast to conventional picture, appear to follow an inverted family hierarchy. Others mix with ordinary quark-lepton families in a way that there may arise a marked violation of unitarity in the CKM matrix for leptons.

    hep-phNPB(2019)·8 citations
17. 17*

    Effects of medium modifications of nucleon form factors on neutrino scattering in dense matter

    Parada T. P. Hutauruk🇰🇷 · Yongseok Oh🇰🇷 · K.Tsushima🇧🇷

    Effects of the in-medium modifications of nucleon form factors on neutrino interaction in dense matter are presented by considering both the weak and electromagnetic interactions of neutrinos with the constituents of the matter. A relativistic mean field and the quark-meson coupling models are respectively adopted for the effective nucleon mass and in-medium nucleon form factors. We calculate the cross-section of neutrino scattering as well as the neutrino mean free path. We found the cross sections of neutrino scattering in cold nuclear medium decreases when the in-medium modifications of the nucleon weak and electromagnetic form factors are taken into account.This reduction results in the enhancement of the neutrino mean free path, in particular at the baryon density of around a few times of the normal nuclear matter density.

    ↳ nucl-thhep-phJPS Conf.Proc.(2019)·4 citations
18. 18*

    Description of the recently observed hypernucleus ${}^{15}{}_{{\Xi }^{-}}$C within a quark-meson coupling model

    R. Shyam🇮🇳 · K. Tsushima🇧🇷

    We investigate within a quark-meson coupling (QMC) model, the structure of the bound ${\Xi }^{-}$ hypernucleus ${}^{15}{}_{{\Xi }^{-}}$C (${}^{14}$N + ${\Xi }^{-}$), which has been observed in a recent analysis of the KEK-E373 experiment. In the QMC model, light quarks in nonoverlapping nucleon and ${\Xi }^{-}$ bags interact self-consistently with isoscalar-scalar ($\sigma$), isoscalar-vector ($\omega$), and isovector-vector ($\rho$) mesons in the mean field approximation. The parameters of the model (quark-meson coupling constants and masses) are mostly fixed from the nuclear matter saturation properties. The QMC model closely reproduces the separation energies of the two ${\Xi }^{-}$ hyperon states in ${}^{15}{}_{{\Xi }^{-}}$C reported in the KEK-E373 analysis, and identifies their quantum numbers. We also make predictions for the cross sections for the production of the ${}^{15}{}_{{\Xi }^{-}}$C hypernuclear specta in the ($K^{-},K^{+}$) reaction on a ${}^{15}$O target within a covariant effective Lagrangian model using the ${\Xi }^{-}$ bound state spinors obtained within the same QMC model.

    ↳ nucl-thhep-exhep-phnucl-ex11 citations
19. 19*

    Anisotropic inflation with coupled $\mathbf{p}$-forms

    Juan P. Beltrán Almeida🇨🇴 · Alejandro Guarnizo🇨🇴 · Ryotaro Kase🇯🇵 · Shinji Tsujikawa🇯🇵 · César A. Valenzuela-Toledo🇨🇴

    We study the cosmology in the presence of arbitrary couplings between $p$-forms in 4-dimensional space-time for a general action respecting gauge symmetry and parity invariance. The interaction between 0-form (scalar field $\varphi$) and 3-form fields gives rise to an effective potential $V_{\mathrm{eff}}(\varphi )$ for the former after integrating out the contribution of the latter. We explore the dynamics of inflation on an anisotropic cosmological background for a coupled system of 0-, 1-, and 2-forms. In the absence of interactions between 1- and 2-forms, we derive conditions under which the anisotropic shear endowed with nearly constant energy densities of 1- and 2-forms survives during slow-roll inflation for an arbitrary scalar potential $V_{\mathrm{eff}}(\varphi )$. If 1- and 2-forms are coupled to each other, we show the existence of a new class of anisotropic inflationary solutions in which the energy density of 2-form is sustained by that of 1-form through their interactions. Our general analytic formulas for the anisotropic shear are also confirmed by the numerical analysis for a concrete inflaton potential.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2019)·21 citations
20. 20*

    Muon Colliders

    Jean Pierre Delahaye🇨🇭 · Marcella Diemoz🇮🇹 · Ken Long🇬🇧 · Bruno Mansoulié🇫🇷 · Nadia Pastrone🇮🇹 · Lenny Rivkin🇨🇭 · Daniel Schulte🇨🇭 · Alexander Skrinsky🇷🇺 · Andrea Wulzer🇨🇭

    Muon colliders have a great potential for high-energy physics. They can offer collisions of point-like particles at very high energies, since muons can be accelerated in a ring without limitation from synchrotron radiation. However, the need for high luminosity faces technical challenges which arise from the short muon lifetime at rest and the difficulty of producing large numbers of muons in bunches with small emittance. Addressing these challenges requires the development of innovative concepts and demanding technologies. The document summarizes the work done, the progress achieved and new recent ideas on muon colliders. A set of further studies and actions is also identified to advance in the field. Finally, a set of recommendations is listed in order to make the muon technology mature enough to be favourably considered as a candidate for high-energy facilities in the future.

    ↳ physics.acc-phhep-exhep-ph354 citations
21. 21*

    General relativity experiment with frozen spin rings

    Andras Laszlo🇭🇺

    In experimental proposals published in the last two decades, a so called frozen spin storage ring concept was proposed for setting upper experimental bounds to electric dipole moment (EDM) of elementary particles. In a recent paper of ours, a fully covariant general relativistic (GR) calculation was presented on the Earth's gravitational modification effect in such mixed magnetic-electric frozen spin storage ring on the spin transport, which could contribute to such measurement. It was shown that similarly to an EDM signal, GR causes a spin precession out of the orbital plane, under the frozen spin condition. The rate of the vertical polarization buildup is predicted to be -a*beta*gamma*g/c, where g is the gravitational acceleration on the surface of the Earth, c is the speed of light, beta*gamma is the particle momentum over mass, and 'a' is its magnetic moment anomaly. It is seen that the effect increases unboundedly with the Lorentz factor gamma. Moreover, it is proportional to the magnetic moment anomaly 'a'. This paper mainly addresses the experimental perspectives to detect this effect in a realistic frozen spin storage ring configuration. Such a measurement would provide a novel test of GR, sampling the tensorial nature of GR at a microscopic level, as acting on the spin vector of elementary particles. The conclusion is that the pertinent GR experiment seems to be realistic with large magnetic moment anomaly particles, such as tritons, helion3 or protons, whereas it is not realistic with small magnetic moment anomaly particles, such as deuterons, muons or electrons.

    ↳ gr-qchep-phhep-thPoS(2019)·5 citations
22. 22*

    Effects of the standing accretion-shock instability and the lepton-emission self-sustained asymmetry in the neutrino emission of rotating supernovae

    Laurie Walk🇩🇰 · Irene Tamborra (Niels Bohr Institute)🇩🇰 · Hans-Thomas Janka🇩🇪 · Alexander Summa (MPA, Garching)🇩🇪

    Rotation of core-collapse supernovae (SNe) affects the neutrino emission characteristics. By comparing the neutrino properties of three three-dimensional SN simulations of a 15 M_sun progenitor (one non-rotating model and two models rotating at different velocities), we investigate how the neutrino emission varies with the flow dynamics in the SN core depending on the different degrees of rotation. The large-amplitude sinusoidal modulations due to the standing accretion-shock instability (SASI) are weaker in both the rotating models than in the non-rotating case. The SN progenitor rotation reduces the radial velocities and radial component of the kinetic energy associated with convection interior to the proto-neutron star. This effect seems to disfavor the growth of the hemispheric neutrino-emission asymmetries associated with the lepton-emission self-sustained asymmetry (LESA). An investigation of the multipole expansion of the neutrino luminosity and the electron neutrino lepton number flux shows a dominant quadrupolar mode in rotating SN models. Our findings highlight the power of using neutrinos as probes of SN hydrodynamics.

    ↳ astro-ph.HEhep-phPRD(2019)·35 citations
23. 23*

    A simple $F(\mathcal{R},\varphi )$ deformation of Starobinsky inflationary model

    Dhimiter D. Canko🇬🇷 · Ioannis D. Gialamas🇬🇷 · George P. Kodaxis🇬🇷

    We study a model including a real scalar field $\varphi$ non-minimally coupled to $F(\mathcal{R})$ gravity, which is conformally equivalent to an Einstein-Hilbert theory, involving two real scalar fields. We consider three special cases of the potential of the field $\varphi$ in the $F(\mathcal{R})$-frame: a vanishing potential, a mass term and a Higgs potential. All these lead to non-trivial two-field potentials in the Einstein-frame which in particular directions resemble the well-known Starobinsky model. We find, that all these cases can yield viable inflationary models in complete agreement with current observational data.

    ↳ hep-thgr-qchep-phEPJC(2020)·73 citations
24. 24*

    Tantalizing dilaton tests from a near-conformal EFT

    Zoltan Fodor🇩🇪 · Kieran Holland🇺🇸 · Julius Kuti🇺🇸 · Chik Him Wong🇩🇪

    The dilaton low-energy effective field theory (EFT) of an emergent light scalar is probed in the paradigm of strongly coupled near-conformal gauge theories. These studies are motivated by models which exhibit small $\beta$-functions near the conformal window (CW), perhaps with slow scale-dependent walking and a light scalar with $0^{++}$ quantum numbers. We report our results from the hypothesis of a dilaton inspired EFT analysis with two massless fermions in the two-index symmetric (sextet) representation of the SU(3) color gauge group. With important caveats in our conclusions, conformal symmetry breaking entangled with chiral symmetry breaking would drive the near-conformal infrared behavior of the theory predicting characteristic dilaton signatures of the light scalar from broken scale invariance when probed on relevant scales of fermion mass deformations. From a recently reasoned choice of the dilaton potential in the EFT description~\cite{Golterman:2016lsd} we find an unexpectedly light dilaton mass in the chiral limit at $m_d/f_{\pi }=1.56(28)$, set in units of the pion decay constant $f_{\pi }$. Subject to further statistical and systematic tests of continued post-conference analysis, this result is significantly lower than our earlier estimates from less controlled extrapolations of the light scalar (the $\sigma$-particle) to the massless fermion limit of chiral perturbation theory. We also discuss important distinctions between the dilaton EFT analysis and the linear $\sigma$-model without dilaton signatures. For comparative reasons, we comment on dilaton tests from recent work with fermions in the fundamental representation with $n_f=8$ flavors.

    ↳ hep-lathep-phPoS(2019)·45 citations
25. 25*

    On Quantum Fields at High Temperature

    Ingolf Bischer🇩🇪 · Thierry Grandou🇫🇷 · Ralf Hofmann🇩🇪

    Revisiting the fast fermion damping rate calculation in a thermalized QED and/or QCD plasma at 4-loop order, focus is put on a peculiar perturbative structure which has no equivalent at zero-temperature. Not surprisingly and in agreement with previous $C^{\star }$-algebraic analyses, this structure renders the use of thermal perturbation theory quite questionable.

    ↳ hep-thhep-phUniverse(2019)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.