Fri·May 15, 2020Friday·May 15, 2020

1. 01*

   On the interpretation of non-resonant phenomena at colliders

   Miguel G. Folgado🇪🇸 · Veronica Sanz🇪🇸

   With null results in resonance searches at the LHC, the physics potential focus is now shifting towards the interpretation of non-resonant phenomena. An example of such shift is the increased popularity of the EFT programme. We can embark on such programme owing to good integrated luminosity and an excellent understanding of the detectors, which will allow these searches to become more intense as the LHC continues. In this paper we provide a framework to perform this interpretation in terms of a diverse set of scenarios, including {\it 1.) } generic heavy new physics described at low energies in terms of a derivative expansion, such as in the EFT approach, {\it 2.)} very light particles with derivative couplings, such as axions or other light pseudo-Goldstone bosons, and {\it 3.)} the effect of a quasi-continuum of resonances, which can come from a number of strongly-coupled theories, extra-dimensional models, clockwork set-ups and their deconstructed cousins. These scenarios are not equivalent despite all non-resonant, although the matching among some of them is possible and we provide it in this paper.

   hep-phhep-exAdv.High Energy Phys.(2021)·7 citations
2. 02*

   Big Bang Nucleosynthesis constraints on sterile neutrino and lepton asymmetry of the Universe

   Graciela B. Gelmini🇺🇸 · Masahiro Kawasaki🇯🇵 · Alexander Kusenko🇺🇸 · Kai Murai🇯🇵 · Volodymyr Takhistov🇺🇸

   We consider the cosmological effects of sterile neutrinos with the masses of $150-450$ MeV. The decay of sterile neutrinos changes the thermal history of the Universe and affects the energy density of radiation at the recombination and the big bang nucleosynthesis (BBN) results. We derive severe constraints on the parameters of sterile neutrinos from the primordial abundances of helium-4 and deuterium. We also find that in a particular model the constraints can be considerably relaxed by assuming a large lepton asymmetry in the active neutrinos. In this case, the consistent parameters result in $N_{\mathrm{eff}}\simeq 3.2-3.4$ and can alleviate the Hubble tension.

   hep-phastro-ph.COJCAP(2020)·82 citations
3. 03*

   New ${\Lambda }_b(6072{)}^0$ state as a $2S$ bottom baryon

   K. Azizi🇮🇷 · Y. Sarac🇹🇷 · H. Sundu🇹🇷

   As a result of continuous developments, the recent experimental searches lead to the observations of new particles at different hadronic channels. Among these hadrons are the excited states of the heavy baryons containing single bottom or charmed quark in their valance quark content. The recently observed ${\Lambda }_b(6072{)}^0$ state is one of these baryons and possibly $2S$ radial excitation of the ${\Lambda }_b$ state. Considering this information from the experiment, we conduct a QCD sum rule analysis on this state and calculate its mass and current coupling constant considering it as a $2S$ radially excited ${\Lambda }_b$ resonance. For completeness, in the analyses, we also compute the mass and current coupling constant for the ground state ${\Lambda }_b^0$ and its first orbital excitation. We also consider the ${\Lambda }_c^{+}$ counterpart of each state and attain their mass, as well. The obtained results are consistent with the experimental data as well as existing theoretical predictions.

   hep-phhep-exhep-latPRD(2020)·15 citations
4. 04*

   Axial-vector form factors of the baryon decuplet with flavor SU(3) symmetry breaking

   Yu-Son Jun🇰🇷 · Jung-Min Suh🇰🇷 · Hyun-Chul Kim🇰🇷

   The axial-vector form factors and axial-vector constants of the baryon decuplet are investigated within a pion mean-field approach, which is also known as the chiral quark-soliton model. Given an axial-vector current with a specified flavor, there are four different form factors of a decuplet baryon. When we consider the singlet, triplet, and octet axial-vector currents, we have twelve different form factors for each member of the baryon decuplet. We compute all these axial-vector form factors of the baryon decuplet, taking into account the rotational $1/N_c$ corrections and effects of flavor SU(3) symmetry breaking. We find that, for a given flavor, two of the form factors for a decuplet baryon are only independent within the present approach. We first examine properties of the axial-vector form factors of the ${\Delta }^{+}$ isobar and ${\Omega }^{-}$ hyperon. We also compare the results of the triplet axial-vector form factors of ${\Delta }^{+}$ with those from lattice QCD and those of the present work for the axial-vector constants of the baryon decuplet with the lattice data. All the results for other members of the baryon decuplet are then presented. The results of the axial charges are compared with those of other works. The axial masses and axial radii are also discussed.

   hep-phhep-latPRD(2020)·11 citations
5. 05*

   Very heavy flavored dibaryons

   Jean-Marc Richard🇫🇷 · Alfredo Valcarce🇪🇸 · Javier Vijande🇪🇸

   We explore the possibility of very heavy dibaryons with three charm quarks and three beauty quarks, $bbbccc$, using a constituent model which should drive to the correct solution in the limit of hadrons made of heavy quarks. The six-body problem is treated rigorously, in particular taking into account the orbital, color and spin mixed-symmetry components of the wave function. Unlike a recent claim based on lattice QCD, no bound state is found below the lowest dissociation threshold.

   hep-phhep-latnucl-thPRL(2020)·41 citations
6. 06*

   Two-pole structures in QCD: Facts, not fantasy!

   Ulf-G. Meißner🇩🇪

   The two-pole structure refers to the fact that particular single states in the spectrum as listed in the PDG tables are often two states. The story began with the $\Lambda (1405)$, when in 2001, using unitarized chiral perturbation theory, it was observed that there are two poles in the complex plane, one close to the $\bar{K}p$ and the other close to the $\pi \Sigma$ threshold. This was later understood combining the SU(3) limit and group-theoretical arguments. Different unitarization approaches that all lead to the two-pole structure have been considered in the mean time, showing some spread in the pole positions. This fact is now part of the PDG book, though it is not yet listed in the summary tables. Here, I will discuss the open ends and critically review approaches that can not deal with this issue. In the meson sector some excited charm mesons are good candidates for such a two-pole structure. Next, I consider in detail the $D_0^{\ast }(2300)$, that is another candidate for this scenario. Combining lattice QCD with chiral unitary approaches in the finite volume, the precise data of the Hadron Spectrum Collaboration for coupled-channel $D\pi$, $D\eta$, $D_s\bar{K}$ scattering in the isospin $I=1/2$ channel indeed reveal its two-pole structure. Further states in the heavy meson sector with $I=1/2$ exhibiting this phenomenon are predicted, especially in the beauty meson sector. I also discuss the relation of these two-pole structures and the possible molecular nature of the states under consideration.

   hep-phhep-exhep-latnucl-ex+1Symmetry(2020)·118 citations
7. 07*

   Dynamical Quark Mass Generation in QCD\textsubscript{3} within the Hamiltonian approach in Coulomb gauge

   Felix Spengler🇩🇪 · Davide Campagnari🇩🇪 · Hugo Reinhardt🇩🇪

   We investigate the equal-time (static) quark propagator in Coulomb gauge within the Hamiltonian approach to QCD in $d=2$ spatial dimensions. Although the underlying Clifford algebra is very different from its counterpart in $d=3$, the gap equation for the dynamical mass function has the same form. The additional vector kernel which was introduced in $d=3$ to cancel the linear divergence of the gap equation and to preserve multiplicative renormalizability of the quark propagator makes the gap equation free of divergences also in $d=2$.

   hep-phhep-thEur.Phys.J.ST(2020)·0 citations
8. 08*

   The double Compton process in astrophysical plasmas

   Andrea Ravenni🇬🇧 · Jens Chluba🇬🇧

   We study the double Compton (DC) process for a wide range of particle energies, extending previous treatments well beyond the soft photon limit, employing both numerical and analytical methods. This allows us to investigate the physics of the DC process up to the highly relativistic regime relevant to electromagnetic particle cascades in the early Universe and photon-dominated astrophysical plasmas. Generalized exact analytic expressions for the DC emissivity in the soft photon limit are obtained. These are compared to existing approximations, for the first time studying the ultra-relativistic regime. We also numerically integrate the full DC collision term calculating the DC emissivity at general particle energies. A careful treatment of DC infrared divergences inside astrophysical plasmas, including subtle effects related to the presence of stimulated DC emission, is discussed. The obtained results can be efficiently represented using the code DCpack, which also allows one to compute average emissivities for general incoming electron and photon distributions. This puts the modelling of the DC process inside astrophysical plasmas on a solid footing and should find applications in particular for computations of the cosmological thermalization problem in the early Universe.

   hep-phastro-ph.HEJCAP(2020)·11 citations
9. 09*

   EFT anomalous dimensions from the S-matrix

   Joan Elias Miró🇮🇹 · James Ingoldby🇮🇹 · Marc Riembau🇨🇭

   We use the on-shell S-matrix and form factors to compute anomalous dimensions of higher dimension operators in the Standard Model Effective Field Theory. We find that in many instances, these computations are made simple by using the on-shell method. We first compute contributions to anomalous dimensions of operators at dimension-six that arise at one-loop. Then we calculate two-loop anomalous dimensions for which the corresponding one-loop contribution is absent, using this powerful method.

   hep-phhep-thJHEP(2020)·86 citations
10. 10*

    Analysis on nonperturbative flavor violation at chiral crossover criticality in QCD

    Mamiya Kawaguchi🇨🇳 · Shinya Matsuzaki🇨🇳 · Akio Tomiya🇺🇸

    We discuss the violation of quark-flavor symmetry at high temperatures, induced from nonperturbative thermal loop corrections and axial anomaly, based on a three-flavor linear-sigma model including an axial-anomaly induced-flavor breaking term. We employ a nonperturbative analysis following the Cornwall-Jackiw-Tomboulis formalism, and show that the model undergoes a chiral crossover with a pseudo-critical temperature, consistently with lattice observations. We find following features regarding the flavor breaking eminent around and above the pseudo-critical temperature: i) up-and down-quark condensates drop faster than the strange quark's toward the criticality, but still keep nonzero value even going far above the critical temperature; ii) the introduced anomaly-related flavor-breaking effect acts as a catalyzer toward the chiral restoration, and reduces the amount of flavor breaking in the up, down and strange quark condensates; iii) a dramatic deformation for the meson flavor mixing structure is observed, in which the anomaly-induced favor breaking is found to be almost irrelevant; iv) the meson spectroscopy gets corrected by the net nonperturbative flavor breaking effects, where the scalar meson mass hierarchy (inverse mass hierarchy) is significantly altered by the presence of the anomaly-related flavor breaking; v) the topological susceptibility significantly gets the contribution from the surviving strange quark condensate, which cannot be dictated by the chiral perturbation theory, and deviates from the dilute instanton gas prediction. There the anomaly-induced flavor breaking plays a role of the destructive interference for the net flavor violation; vi) the U(1)_A breaking is enhanced by the strange quark condensate, which may account for the tension in the effective U(1)_A restoration observed on lattices with two flavors and 2+1 flavors near the chiral limit.

    hep-phhep-lathep-thnucl-thPRD(2021)·18 citations
11. 11*

    $Z^0$ boson associated b-jet production in high-energy nuclear collisions

    Sa Wang🇨🇳 · Wei Dai🇨🇳 · Ben-Wei Zhang🇨🇳 · Enke Wang🇨🇳

    The production of vector boson tagged heavy quark jets potentially provides new tools to probe the jet quenching effect. In this paper, we present the first theoretical study on the angular correlations ($\Delta {\varphi }_{bZ}$), transverse momentum imbalance ($x_{bZ}$), and nuclear modification factor ($I_{AA}$) of $Z^0$ boson tagged b-jets in heavy-ion collisions, which was performed using a Monte Carlo transport model. We find that the medium modification of the $\Delta {\varphi }_{bZ}$ for $Z^0+$b-jet has a weaker dependence on $\Delta {\varphi }_{bZ}$ than that for $Z^0+$jet, and the modification patterns are sensitive to the initial jet $p_T$ distribution. Additionally, with the high purity of the quark jet in $Z^0+$(b-)jet production, we calculate the momentum imbalance $x_{bZ}$ and the nuclear modification factor $I_{AA}$ of $Z^0+$b-jet in Pb+Pb collisions. We observe a smaller $\Delta ⟨x_{jZ}⟩$ and larger $I_{AA}$ of $Z^0+$b-jet in Pb+Pb collisions relative to those of $Z^0+$jet, which may be an indication of the mass effect of jet quenching and can be tested in future measurements.

    hep-phnucl-exnucl-thCPC(2023)·19 citations
12. 12*

    A New Method to Extract Information of Near-Threshold Resonances: Uniformized Pole-Sum Representation of Green's Function and T-matrix

    Wren Yamada🇯🇵 · Osamu Morimatsu🇯🇵

    We propose a new, simple model-independent method to extract information of near-threshold resonances, such as complex energies and residues. The method is based on the observation that the Green's function and the T-matrix can be represented as the sum of all poles, both bound and resonant poles, in the complex plane of a variable in which the Green's function and the T-matrix are single-valued functions. The symmetries of poles, which arise from the unitarity of the S-matrix, naturally impose the sum to obey the proper threshold behaviors. The imaginary part of Green's function and the T-matrix are directly related to observables such as scattering cross sections or invariant or missing mass distributions of hadron resonances. Thus we can determine their pole positions and residues by fitting their imaginary part to observables. We also test the new method by regarding the imaginary part of the $T$-matrix calculated exactly in a model theory as virtual experimental data. As a model theory, we take double-channel meson-baryon scatterings in the chiral unitary model with channels, $\overline{K}N(I=0)$, and $\pi \Sigma (I=0)$. By fitting the imaginary part of the $T$-matrix calculated in the model theory by that of the uniformized pole-sum, we obtain the pole positions and residues. Comparing the obtained results with those of the exact calculation in the model theory, we conclude that our new method works very well.

    hep-phnucl-thPRC(2020)·13 citations
13. 13*

    A precision calculation of relic neutrino decoupling

    Kensuke Akita🇯🇵 · Masahide Yamaguchi🇯🇵

    We study the distortions of equilibrium spectra of relic neutrinos due to the interactions with electrons, positrons, and neutrinos in the early Universe. We solve the integro-differential kinetic equations for the neutrino density matrix, including three-flavor oscillations and finite temperature corrections from QED up to the next-to-leading order $\mathcal{O}(e^3)$ for the first time. In addition, the equivalent kinetic equations in the mass basis of neutrinos are directly solved, and we numerically evaluate the distortions of the neutrino spectra in the mass basis as well, which can be easily extrapolated into those for non-relativistic neutrinos in the current Universe. In both bases, we find the same value of the effective number of neutrinos, $N_{\mathrm{eff}}=3.044$, which parameterizes the total neutrino energy density. The estimated error for the value of $N_{\mathrm{eff}}$ due to the numerical calculations and the choice of neutrino mixing parameters would be at most 0.0005.

    hep-phastro-ph.COJCAP(2020)·376 citations
14. 14*

    Magnetic field dependent 't Hooft determinant extended Nambu--Jona-Lasinio Model

    João Moreira🇵🇹 · Pedro Costa🇵🇹 · Tulio E. Restrepo🇧🇷

    We study the implications of recent lattice QCD results for the magnetic field dependence of the quarks dynamical masses on the 't Hooft determinant extended Nambu--Jona-Lasinio Model in the light and strange quark sectors (\emph{up}, \emph{down} and \emph{strange}). The parameter space is constrained at vanishing magnetic field, using the quarks dynamical masses and the meson spectra, whereas at non-vanishing magnetic field strength the dependence of the dynamical masses of two of the quark flavors is used to fit a magnetic field dependence on the model couplings, both the four-fermion Nambu--Jona-Lasinio interaction and the six-fermion 't Hooft flavor determinant. We found that this procedure reproduces the inverse magnetic catalysis, and the strength of the scalar coupling decreases with the magnetic field, while the strength of the six-fermion 't Hooft flavor determinant increases with the magnetic field.

    hep-phPRD(2020)·12 citations
15. 15*

    Spectrum of the Hidden-Bottom and the Hidden-Charm/Strange Exotics in the Dynamical Diquark Model

    Jesse F. Giron🇺🇸 · Richard F. Lebed🇺🇸

    The lightest hidden-bottom tetraquarks in the dynamical diquark model fill an $S$-wave multiplet consisting of 12 isomultiplets. We predict their masses and dominant bottomonium decay channels using a simple 3-parameter Hamiltonian that captures the core fine-structure features of the model, including isospin dependence. The only experimental inputs needed are the corresponding observables for $Z_b(10610)$ and $Z_b(10650)$. The mass of $X_b$, the bottom analogue to $X(3872)$, is highly constrained in this scheme. In addition, using lattice-calculated potentials we predict the location of the center of mass of the $P$-wave multiplet and find that $Y(10860)$ fits well but the newly discovered $Y(10750)$ does not, more plausibly being a $D$-wave bottomonium state. Using similar methods, we also examine the lowest $S$-wave multiplet of 6 $c\bar{c}s\bar{s}$ states, assuming as in earlier work that $X(3915)$ and $Y(4140)$ are members, and predict the masses and dominant charmonium decay modes of the other states. We again use lattice potentials to compute the centers of mass of higher multiplets, and find them to be compatible with the masses of $Y(4626)$ ($1P$) and $X(4700)$ ($2S$), respectively.

    hep-phhep-exnucl-thPRD(2020)·54 citations
16. 16*

    Pair production of dark particles in meson decays

    Matheus Hostert🇺🇸 · Kunio Kaneta🇺🇸 · Maxim Pospelov🇺🇸

    Rare decays of $K$ and $B$ mesons provide a powerful probe of dark sectors with light new particles. We show that the pair production of $O(100\mathrm{MeV})$ dark states can be probed with the decays of $K_L$ mesons, owing to the enhanced two-body kinematics, $K_L\to X_1{X}_2$ or $X_2{X}_2$. If either or these two particles is unstable, e.g. $X_2\to X_1{\pi }^0$, $X_2\to X_1\gamma$ or $X_{1,2}\to \gamma \gamma$, such decays could easily mimic $K_L\to {\pi }^0\nu \overline{\nu }$ signatures, while not being ruled out by the decays of charged kaons. We construct explicit models that have enhanced $K_L$ decay signatures, and are constrained by the results of the KOTO experiment. We note that recently reported excess events can also be accommodated while satisfying all other constraints ($B$ decays, colliders, beam dumps). These models are based on the extensions of the gauge and/or scalar sector of the theory. The lightest of $X_{1,2}$ particles, if stable, could constitute the entirety of dark matter.

    hep-phhep-exPRD(2020)·36 citations
17. 17*

    Renormalization of Higher-Dimensional Operators from On-shell Amplitudes

    Pietro Baratella🇩🇪 · Clara Fernandez🇪🇸 · Alex Pomarol🇪🇸

    On-shell amplitude methods allow to derive one-loop renormalization effects from just tree-level amplitudes, with no need of loop calculations. We derive a simple formula to obtain the anomalous dimensions of higher-dimensional operators from a product of tree-level amplitudes. We show how this works for dimension-6 operators of the Standard Model, providing explicit examples of the simplicity, elegance and efficiency of the method. Many anomalous dimensions can be calculated from the same Standard Model tree-level amplitude, displaying the attractive recycling aspect of the on-shell method. With this method, it is possible to relate anomalous dimensions that in the Feynman approach arise from very different diagrams, and obtain non-trivial checks of their relative coefficients. We compare our results to those in the literature, where ordinary methods have been applied.

    hep-phhep-thNPB(2020)·82 citations
18. 18*

    Muons in supernovae: implications for the axion-muon coupling

    Robert Bollig🇩🇪 · William DeRocco🇺🇸 · Peter W. Graham🇺🇸 · Hans-Thomas Janka🇩🇪

    The high temperature and electron degeneracy attained during a supernova allow for the formation of a large muon abundance within the core of the resulting proto-neutron star. If new pseudoscalar degrees of freedom have large couplings to the muon, they can be produced by this muon abundance and contribute to the cooling of the star. By generating the largest collection of supernova simulations with muons to date, we show that observations of the cooling rate of SN 1987A place strong constraints on the coupling of axion-like particles to muons, limiting the coupling to $g_{a\mu }<10^{-7.5}{\text{GeV}}^{-1}$.

    hep-phastro-ph.HEPRL(2020)·159 citations
19. 19*

    Visible Decay of Astrophysical Neutrinos at IceCube

    Asli Abdullahi🇬🇧 · Peter B. Denton🇺🇸

    Neutrino decay modifies neutrino propagation in a unique way; not only is there flavor changing as there is in neutrino oscillations, there is also energy transport from initial to final neutrinos. The most sensitive direct probe of neutrino decay is currently IceCube which can measure the energy and flavor of neutrinos traveling over extragalactic distances. For the first time we calculate the flavor transition probability for the cases of visible and invisible neutrino decay, including the effects of the expansion of the universe, and consider the implications for IceCube. As an example, we demonstrate how neutrino decay addresses a tension in the IceCube data. We also provide a publicly available code to calculate the effect of visible decay.

    hep-phastro-ph.HEhep-exPRD(2020)·58 citations
20. 20*

    Particles and the Universe

    George Lazarides🇬🇷

    The early stages of the universe evolution are discussed according to the hot big bang model and the grand unified theories. The shortcomings of big bang are summarized and their resolution by inflationary cosmology is sketched. Cosmological inflation, the subsequent oscillation and decay of the inflaton field, and the resulting reheating of the universe are studied in some detail. The density perturbations produced by inflation and the temperature fluctuations of the cosmic microwave background radiation are introduced. Baryogenesis via non-thermal leptogenesis is analyzed and dark energy and matter in the universe are presented. Quantum gravity and string theory are very briefly introduced. The problem of initial conditions for inflation is discussed in the light of string theory and the possibly detectable primordial gravity waves from inflation are mentioned.

    hep-phastro-ph.COPoS(2020)·0 citations
21. 21*

    Topology and axions in QCD

    Maria Paola Lombardo🇮🇹 · Anton Trunin🇷🇺

    QCD axions are at the crossroads of QCD topology and Dark Matter searches. We present here the current status of topological studies on the lattice, and their implication on axion physics. We outline the specific challenges posed by lattice topology, the different proposals for handling them, the observable effects of topology on the QCD spectrum and its interrelation with chiral and axial symmetries. We review the transition to the Quark Gluon Plasma, the fate of topology at the transition, and the approach to the high temperature limit. We discuss the extrapolations needed to reach the regime of cosmological relevance, and the resulting constraints on the QCD axion.

    ↳ hep-lathep-phInt.J.Mod.Phys.A(2020)·58 citations
22. 22*

    Localized massive excitation of quantum gravity as a dark particle

    Ken-ji Hamada🇯🇵

    We construct a static and spherical excited state without singularities in renormalizable quantum gravity with background-free nature asymptotically. Its diameter is given by a correlation length of the quantum gravity, longer than the Planck length by 2 orders of magnitude, and it has a Schwarzschild tail outside. The quantum gravity dynamics inside is described by employing a nonperturbative expression of higher-order corrections assumed from a physical requirement that the dynamics disappear at the edge where it is in strong coupling. A running coupling constant that is a manifestation of nonlinearity and nonlocality is managed by approximating it as a mean field that depends on the radial coordinate. If the mass is several times the Planck mass, we can set up a system of linearized equations of motion for the gravitational potentials incorporating the running effect and obtain the excited state as its solution. It may be a candidate for dark matter, and will give a new perspective on black hole physics.

    ↳ hep-thgr-qchep-phPRD(2020)·5 citations
23. 23*

    Scattering length in holographic confining theories

    Carlos Hoyos🇪🇸 · Niko Jokela🇫🇮 · Daniel Logares🇪🇸

    The low-energy effective theory description of a confining theory, such as QCD, is constructed including local interactions between hadrons organized in a derivative expansion. This kind of approach also applies more generically to theories with a mass gap, once the relevant low energy degrees of freedom are identified. The strength of local interactions in the effective theory is determined by the low momentum expansion of scattering amplitudes, with the scattering length capturing the leading order. We compute the main contribution to the scattering length between two spin-zero particles in strongly coupled theories using the gauge/gravity duality. We study two different theories with a mass gap: a massive deformation of $\mathcal{N}=4$ super Yang-Mills theory ($\mathcal{N}=1^{\ast }$) and a non-supersymmetric five-dimensional theory compactified on a circle. These cases have a different realization of the mass gap in the dual gravity description: the former is the well-known GPPZ singular solution and the latter a smooth $Ad{S}_6$ soliton geometry. Despite disparate gravity duals, we find that the scattering lengths have strikingly similar functional dependences on the masses of the particles and on the conformal dimension of the operators that create them. This evinces universal behavior in the effective description of gapped strongly coupled theories beyond what is expected from symmetry considerations alone.

    ↳ hep-thhep-phPRD(2020)·10 citations
24. 24*

    New analytic continuations for the Appell $F_4$ series from quadratic transformations of the Gauss ${}_2{F}_1$ function

    B. Ananthanarayan🇮🇳 · Samuel Friot🇫🇷 · Shayan Ghosh🇩🇪 · Anthony Hurier🇮🇳

    We present new analytic continuation formulas for the Appell $F_4(a,b;c,d;x,y)$ double hypergeometric series where $d=a-b+1$, which allows quadratic transformations of the Gauss ${}_2{F}_1$ hypergeometric function to be used in the intermediate steps of the derivation. Such formulas are of relevance to loop calculations of quantum field theory where they can been used, for instance, to obtain new series representations of the two-loop massive sunset Feynman diagram. The analytic continuation procedure introduced in this paper is also sufficiently general so as to find uses elsewhere.

    ↳ hep-thhep-phmath-phmath.MP18 citations
25. 25*

    Cardy's Conjecture and the Spectrum of Infrared Strongly-Coupled Quantum Field Theories

    Daniel Davies🇺🇸

    Cardy's conjecture about the evolution of the trace anomaly under renormalization group (RG) flows is re-interpreted as an exact, non-perturbative statement about the scaling dimension of terms in the Lagrangian of the theory. When viewed in this way, the conjecture implies that field theories which are strongly coupled in the infrared (IR) may generically host states that are not manifest as solutions to the ultraviolet (UV) complete theory's equations of motion. In particular, the scaling dimension of operators in the Hamiltonian may deviate from their classical values by $\mathcal{O}(1)$ corrections in the IR, circumventing an old argument by Derrick about the non-existence of such states\cite{1}. We show that this framework provides a natural way to estimate the masses of these states using perturbation theory, and suggests a preferred reorganization of the degrees of freedom in the IR.

    ↳ hep-thhep-lathep-ph1 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.