Thu·Jan 23, 2020Thursday·January 23, 2020

1. 01*

   The Lee model: a tool to study decays

   Francesco Giacosa🇵🇱

   We describe -- in a didactical and detailed way -- the so-called Lee model (which shares similarities with the Jaynes-Cummings and Friedrichs models) as a tool to study unstable quantum states/particles. This Lee model is based on Quantum Mechanics (QM) but possesses some of the features of Quantum Field Theory (QFT). The decay process can be studied in great detail and typical QFT quantities such as propagator, one-loop resummation, and Feynman rules can be introduced. Deviations from the exponential decay law as well as the Quantum Zeno effects can be studied within this framework. The survival probability amplitude as a Fourier transform of the energy distribution, the normalization of the latter, and the Breit-Wigner limit can be obtained in a rigorous mathematical approach.

   hep-phquant-phJ.Phys.Conf.Ser.(2020)·7 citations
2. 02*

   Probing Nuclear Structure with Future Colliders

   T. J. Hobbs🇺🇸 · Pavel M. Nadolsky🇺🇸 · Fredrick I. Olness🇺🇸 · Bo-Ting Wang🇺🇸

   Improved knowledge of the nucleon structure is a crucial pathway toward a deeper understanding of the fundamental nature of the QCD interaction, and will enable important future discoveries. The experimental facilities proposed for the next decade offer a tremendous opportunity to advance the precision of our theoretical predictions to unprecedented levels. In this report we briefly highlight some of the recently developed tools and techniques which, together with data from these new colliders, have the potential to revolutionize our understanding of the QCD theory in the next decade.

   hep-ph1 citation
3. 03*

   SUSY, Casimir scaling and probabilistic properties of gluon and quark jets evolution

   Anatoly V. Kotikov🇷🇺 · Oleg V. Teryaev🇷🇺

   We study the new relation [1] between the anomalous dimensions, resummed through next-to-next-to-leading-logarithmic order, in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equations for the first Mellin moments D_{q,g}(\mu^2) of the fragmentation functions, which correspond to the average multiplicities of hadrons in jets initiated by quarks and gluons, respectively. This relation is shown to lead to probabilistic properties of the properly rescaled parton jet multiplicities obtained from standard ones by extracting the quark and gluon "color charges" C_F and C_A, respectively.

   hep-phPRD(2021)·2 citations
4. 04*

   Deconfinement temperature in AdS/QCD from the spectrum of scalar glueballs

   S. S. Afonin🇷🇺 · A. D. Katanaeva🇷🇺 · E. V. Prokhvatilov🇷🇺 · M. I. Vyazovsky🇷🇺

   We scrutinize various holographic estimations of the deconfinement temperature within the bottom-up AdS/QCD models. A special emphasis is put on the recent idea of isospectral potentials in the holographic approach. It is demonstrated that different models from an isospectral family (i.e., the models leading to identical predictions for the spectrum of hadrons with fixed quantum numbers) result in different predictions for the deconfinement temperature. This difference is found to be quite small in the scalar glueball channel but very large in the vector meson channel which is often used for fixing parameters of holographic models. The observed stability in the former case clearly favors the choice of the glueball channel for thermodynamic predictions in AdS/QCD models, with the scalar glueball trajectory being taken from lattice simulations and used as a basic input in improved versions of the Soft Wall holographic model.

   hep-phhep-thActa Phys.Polon.Supp.(2020)·2 citations
5. 05*

   Oscillation tomography of the Earth with solar neutrinos and future experiments

   Pouya Bakhti🇮🇷 · Alexei Yu. Smirnov🇩🇪

   We study in details the Earth matter effects on the boron neutrinos from the Sun using recently developed 3D models of the Earth. The models have a number of new features of the density profiles, in particular, a substantial deviation from spherical symmetry. In this connection, we further elaborate on relevant aspects of oscillations (${ϵ}^2$ corrections, adiabaticity violation, entanglement, {\it etc.}) and the attenuation effect. The night excesses of the $\nu e-$ and $\nu N-$ events and the Day-Night asymmetries, $A_{ND}$, are presented in terms of the matter potential and the generalized energy resolution functions. The energy dependences of the cross-section and the flux improve the resolution, and consequently, sensitivity to remote structures of the profiles. The nadir angle ($\eta$) dependences of $A_{ND}$ are computed for future detectors DUNE, THEIA, Hyper-Kamiokande, and MICA at the South pole. Perspectives of the oscillation tomography of the Earth with the boron neutrinos are discussed. Next-generation detectors will establish the integrated day-night asymmetry with high confidence level. They can give some indications of the $\eta -$ dependence of the effect, but will discriminate among different models at most at the $(1-2)\sigma$ level. For high-level discrimination, the MICA-scale experiments are needed. MICA can detect the ice-soil borders and perform unique tomography of Antarctica.

   hep-phPRD(2020)·27 citations
6. 06*

   Relativistic hypernuclear compact stars with calibrated equations of state

   M. Fortin🇵🇱 · A. R. Raduta🇷🇴 · S. Avancini🇧🇷 · C. Providência🇵🇹

   Within the covariant density functional theory of hypernuclear matter we build a series of equations of state for hypernuclear compact stars, by calibrating the coupling constants of the $\Xi$-hyperon to the experimental binding energy of the single-$\Xi$ hypernuclei ${}_{{\Xi }^{-}}^{15}$C and ${}_{{\Xi }^{-}}^{12}$Be. Coupling constants of the $\Lambda$-hyperon to nucleons have been calibrated on a vast collection of experimental data on single $\Lambda$-hypernuclei and we employ those values. Uncertainties on the couplings of the $\Sigma$-hyperon to nuclear matter, due to lack of experimental data, are accounted for by allowing for a wide variation of the well depth of $\Sigma$ at rest in symmetric saturated nuclear matter. To account for uncertainties in the nucleonic sector at densities much larger than the saturation density, a rich collection of parametrizations is employed, some of them in agreement with existing constraints from nuclear physics and astrophysics. Neutron star properties are investigated with all these calibrated equations of state. The effects of the presence of hyperons on the radius, on the tidal deformability, on the moment of inertia, and on the nucleonic direct Urca process are discussed. The sensitivity of the hyperonic direct Urca processes to uncertainties in the nucleonic and hyperonic sectors is also addressed. It is shown that the relative variations of the radius, tidal deformability and moment of inertia from the values that characterize purely nucleonic stars are linearly correlated with the strangeness fraction. The maximum radius deviation, obtained for most massive neutron stars, is $\approx 10\%$. The reduction of the maximum mass, triggered by nucleation of strangeness, is estimated at $\approx 15-20\%$, out of which 5\% comes from insufficient information on the $\Sigma$-hyperon interactions.

   hep-phastro-ph.HEnucl-thPRD(2020)·61 citations
7. 07*

   Spectroscopy of ${\mathbf{B}}_{\mathbf{c}}$ mesons and the possibility of finding exotic ${\mathbf{B}}_{\mathbf{c}}$-like structures

   Pablo G. Ortega🇪🇸 · Jorge Segovia🇪🇸 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸

   The bottom-charmed ($B_c$) mesons are more stable than their charmonium ($c\bar{c}$) and bottomium ($b\bar{b}$) partners because they cannot annihilate into gluons. However, the low production cross-sections and signal-to-background ratios avoided until now their clear identification. The recent experimental results reported by CMS and LHCb at CERN open the possibility of having a $B_c$ spectrum as complete as the ones of charmonium and bottomonium. Motivated by this expectation, we compute bottom-charmed meson masses in the region energies in which decay meson-meson thresholds are opened, looking for the analogs to the $X(3872)$ in the $B_c$ spectroscopy. We use a constituent quark model in which quark-antiquark degrees of freedom are complemented by four-body Fock states configurations. The model has been applied to a wide range of hadronic observables, in particular to the $X(3872)$, and thus the model parameters are completely constrained. No extra states are found in the $J^P=0^{+}$ and $J^P=1^{+}$ sectors. However, in the $J^P=2^{+}$ sector we found an additional state very close to the $D^{\ast }{B}^{\ast }$ threshold which could be experimentally detected.

   hep-phEPJC(2020)·50 citations
8. 08*

   Study the molecular nature of $\sigma$, $f_0(980)$, and $a_0(980)$ states

   Hiwa A. Ahmed🇨🇳 · C. W. Xiao🇨🇳

   We investigate the characteristics of $\sigma$, $f_0(980)$, and $a_0(980)$ with the formalism of chiral unitary approach. With the dynamical generation of them, we make a further study of their properties by evaluating the couplings, the compositeness, the wave functions and the radii. We also research their properties in the single channel interactions, where the $a_0(980)$ can not be reproduced in the $K\bar{K}$ interactions with isospin $I=1$ since the potential is too weak. In our results, the states of $\sigma$ and $f_0(980)$ can be dynamically reproduced stably with varying cutoffs both in the coupled channel and the single channel cases. We find that the $\pi \eta$ components is much important in the coupled channel interactions to dynamically reproduce the $a_0(980)$ state, which means that $a_0(980)$ state can not be a pure $K\bar{K}$ molecular state. We obtain their radii as: $|⟨r^2⟩{|}_{f_0(980)}=1.80\pm 0.35$ fm, $|⟨r^2⟩{|}_{\sigma }=0.68\pm 0.05$ fm and $|⟨r^2⟩{|}_{a_0(980)}=0.94\pm 0.09$ fm. Based on our investigation results, we conclude that the $f_0(980)$ state is mainly a $K\bar{K}$ bound state, the $\sigma$ state a resonance of $\pi \pi$ and the $a_0(980)$ state a loose $K\bar{K}$ bound state. From the results of the compositeness, they are not pure molecular states and have something non-molecular components, especially for the $\sigma$ state.

   hep-phPRD(2020)·45 citations
9. 09*

   Determination of the lightest strange resonance $K_0^{\ast }(700)$ or $\kappa$, from a dispersive data analysis

   J.R. Peláez🇪🇸 · A. Rodas🇺🇸

   In this work we present a precise and model-independent dispersive determination from data of the existence and parameters of the lightest strange resonance $\kappa /K_0^{\ast }(700)$. We use both subtracted and unsubtracted partial-wave hyperbolic and fixed-$t$ dispersion relations as constraints on combined fits to $\pi K\to \pi K$ and $\pi \pi \to K\bar{K}$ data. We then use the hyperbolic equations for the analytic continuation of the isospin $I=1/2$ scalar partial wave to the complex plane, in order to determine the $\kappa /K_0^{\ast }(700)$ and $K^{\ast }(892)$ associated pole parameters and residues.

   hep-phhep-exhep-latPRL(2020)·46 citations
10. 10*

    Effects of local event-by-event conservation laws in ultra-relativistic heavy ion collisions at the particlization

    Dmytro Oliinychenko🇺🇸 · Shuzhe Shi🇨🇦 · Volker Koch🇺🇸

    Many simulations of relativistic heavy ion collisions involve the switching from relativistic hydrodynamics to kinetic particle transport. This switching entails the sampling of particles from the distribution of energy, momentum and conserved currents provided by hydrodynamics. Usually this sampling ensures the conservation of these quantities only on the average, i.e. the conserved quantities may actually fluctuate among the sampled particle configurations and only their averages over many such configurations agree with their values from hydrodynamics. Here we apply a recently invented method [Oliinychenko, Koch; PRL 123, 18, 182302 (2019)] to ensure conservation laws for each sampled configuration in spatially compact regions (patches) and study their effects: from the well-known (micro-)canonical suppression of means and variances to little studied (micro-)canonical correlations and higher order fluctuations. Most of these effects are sensitive to the patch size. Many of them do not disappear even in the thermodynamic limit, when the patch size goes to infinity. The developed method is essential for particlization of stochastic hydrodynamics. It is useful for studying the chiral magnetic effect, small systems, and in general for fluctuation and correlation observables.

    hep-phnucl-thPRC(2020)·31 citations
11. 11*

    Theoretical constraints on the Higgs potential of the general $331$ model

    Antonio Costantini🇮🇹 · Margherita Ghezzi🇩🇪 · Giovanni Marco Pruna🇮🇹

    This article reviews the theoretical constraints on the scalar potential of a general extension of the Standard Model that encompasses a $SU(3{)}_c\times SU(3{)}_L\times U(1{)}_X$ gauge symmetry. In this respect, the boundedness-from-below is analysed to identify the correct criteria for obtaining the physical minima of the Higgs parameter space. Furthermore, perturbativity and unitarity bounds are discussed in light of the exact diagonalisation of the scalar fields. This study represents a framework for fast numerical checks on specific $331$ Model benchmarks that are relevant for future collider searches.

    hep-phhep-thPLB(2020)·19 citations
12. 12*

    Brazilian Participation in the Next-Generation Collider Experiments

    W. L. Aldá Júnior🇧🇷 · C. A. Bernardes🇧🇷 · D. De Jesus Damião🇧🇷 · M. Donadelli🇧🇷 · D. E. Martins🇧🇷 · G. Gil da Silveira🇧🇷 · C. Hensel🇧🇷 · H. Malbouisson🇧🇷 · A. Massafferri🇧🇷 · E. M. da Costa🇧🇷 · C. Mora Herrera🇧🇷 · I. Nasteva🇧🇷 and 4 other authors

    This proposal concerns the participation of the Brazilian High-Energy Physics community in the next-generation collider experiments. As the LHC at CERN is getting ready for its third data-taking period, Run 3, with increased centre-of-mass energy at the nominal 14 TeV and upgraded detectors, the global High-Energy Physics community is converging towards the materialisation of new powerful colliders which could explore the characteristics of the Higgs boson and advance the search of physics beyond the Standard Model. This means that in the next couple of years the technical proposals for the experiments that will run in such colliders will be submitted for review, collaborations will be formed and large scale funding will be requested at different stages across the globe. Our aim is to organise a common effort from the Brazilian HEP community of optimised resources and time, in order to produce a higher impact contribution to our chosen experiment and more broadly in the field of High-Energy Physics.

    ↳ hep-exhep-ph0 citations
13. 13*

    Axial U(1) symmetry and mesonic correlators at high temperature in $N_f=2$ lattice QCD

    Kei Suzuki🇯🇵 · Sinya Aoki🇯🇵 · Yasumichi Aoki🇯🇵 · Guido Cossu🇬🇧 · Hidenori Fukaya🇯🇵 · Shoji Hashimoto🇯🇵 · Christian Rohrhofer (JLQCD Collaboration)🇯🇵

    We investigate the high-temperature phase of QCD using lattice QCD simulations with $N_f=2$ dynamical Möbius domain-wall fermions. On generated configurations, we study the axial $U(1)$ symmetry, overlap-Dirac spectra, screening masses from mesonic correlators, and topological susceptibility. We find that some of the observables are quite sensitive to lattice artifacts due to a small violation of the chiral symmetry. For those observables, we reweight the Möbius domain-wall fermion determinant by that of the overlap fermion. We also check the volume dependence of observables. Our data near the chiral limit indicates a strong suppression of the axial $U(1)$ anomaly at temperatures $\ge$ 220 MeV.

    ↳ hep-lathep-phPoS(2020)·15 citations
14. 14*

    Classification of discrete modular symmetries in Type IIB flux vacua

    Tatsuo Kobayashi🇯🇵 · Hajime Otsuka🇯🇵

    We classify discrete modular symmetries in the effective action of Type IIB string on toroidal orientifolds with three-form fluxes, emphasizing on $T^6/{\mathbb{Z}}_2$ and $T^6/({\mathbb{Z}}_2\times {\mathbb{Z}}_2^{\prime })$ orientifold backgrounds. On the three-form flux background, the modular group is spontaneously broken down to its congruence subgroup whose pattern is severely constrained by a quantization of fluxes and tadpole cancellation conditions. We explicitly demonstrate that the congruence subgroups appearing in the effective action arise on magnetized D-branes wrapping certain cycles of tori.

    ↳ hep-thhep-phPRD(2020)·54 citations
15. 15*

    Equivalence between first-order causal and stable hydrodynamics and Israel-Stewart theory for boost-invariant systems with a constant relaxation time

    Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Jorge Noronha🇺🇸 · Radoslaw Ryblewski🇵🇱

    We show that the recently formulated causal and stable first-order hydrodynamics has the same dynamics as Israel-Stewart theory for boost-invariant, Bjorken expanding systems with a conformal equation of state and a regulating sector determined by a constant relaxation time. In this case, the general solution of the new first-order formulation can be determined analytically.

    ↳ nucl-thhep-phPLB(2020)·27 citations
16. 16*

    Generation of strong magnetic fields in a nascent neutron star accounting for the chiral magnetic effect

    Maxim Dvornikov (1 and 2)🇷🇺 · V. B. Semikoz (1)🇷🇺 · D. D. Sokoloff (3) ((1) IZMIRAN, (2) Tomsk State University, (3) Moscow State University)🇷🇺

    We propose the mean field dynamo model for the generation of strongest magnetic fields, $B\sim 10^{15}\mathrm{G}$, in a neutron star (NS) accounting for the chiral magnetic effect (CME) driven by the shock in a supernova (SN) progenitor of that NS. The temperature jump at a narrow shock front, where an initial magnetic field existing in inflowing matter rises sharply, is the source of the CME that prevails significantly the erasure of the CME due to the spin-flip through Coulomb collisions in plasma. The growth of the magnetic field just behind the shock given by the instability term $\nabla \times (\alpha \mathbf{B})$ in induction equation, stops after a successful SN explosion that throws out the mantle of a protoneutron star. As a result, such an explosion interrupts the transfer of strongly magnetized plasma from the shock onto NS surface and leads to the saturation of the magnetic field. Assuming the rigid protostar rotation, we employ the mean field dynamo, which is similar to the ${\alpha }^2$-dynamo known in the standard magnetohydrodynamics (MHD). The novelty of our model is that ${\alpha }^2$-dynamo is based on concepts of particle physics, applied in MHD, rather than by a mirror asymmetry of convective vortices in the rotating convection.

    ↳ astro-ph.HEhep-phPRD(2020)·9 citations
17. 17*

    Primordial black holes as dark matter and gravitational waves from single-field polynomial inflation

    Guillermo Ballesteros🇪🇸 · Julián Rey🇪🇸 · Marco Taoso🇮🇹 · Alfredo Urbano🇮🇹

    We consider the possibility that the majority of dark matter in our Universe consists of black holes of primordial origin. We determine the conditions under which such black holes may have originated from a single-field model of inflation characterized by a quartic polynomial potential. We also explore the effect of higher-dimensional operators. The large power spectrum of curvature perturbations that is needed for a large black hole abundance sources sizable second order tensor perturbations. The resulting stochastic background of primordial gravitational waves could be detected by the future space-based observatories LISA and DECIGO or --as long as we give up on the dark matter connection--by the ground-based Advanced LIGO-Virgo detector network.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2020)·144 citations

* 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.