Thu·Oct 26, 2017Thursday·October 26, 2017

1. 01*

   Neutral meson properties under an external magnetic field in nonlocal chiral quark models

   D. Gomez Dumm🇦🇷 · M.F. Izzo Villafañe🇦🇷 · N.N. Scoccola🇦🇷

   We study the behavior of neutral meson properties in the presence of a static uniform external magnetic field in the context of nonlocal chiral quark models. The formalism is worked out introducing Ritus transforms of Dirac fields, which allow to obtain closed analytical expressions for ${\pi }^0$ and $\sigma$ meson masses and for the ${\pi }^0$ decay constant. Numerical results for these observables are quoted for various parameterizations. In particular, the behavior of the ${\pi }^0$ meson mass with the magnetic field is found to be in good agreement with lattice QCD results. It is also seen that the Goldberger-Treiman and Gell-Mann-Oakes-Renner chiral relations remain valid within these models in the presence of the external magnetic field.

   hep-phPRD(2018)·51 citations
2. 02*

   Higgs decay mediated by top-quark with flavor-changing neutral scalar interactions

   J. A. Orduz-Ducuara🇲🇽

   We explore the flavor-changing parameters mediated by a Higgs boson within the THDM-III context. In particular, the $h\to t^{\ast }c$ processes, and check the high suppression for the FC in the THDM-III context for the low $t_{\beta }$ parameters. Our exploration in the ${\chi }_{ij}^u-{\chi }_{ij}^d-$parameter space shows the allowed regions for different $t_{\beta }^{}$ values. We explored different modes for Higgs decays, considered the experimental constraints to get scattering plots for the FC parameters and some relevant decay modes. We expect future results to figure out the FC and its implications in the scalar sector.

   hep-phJ.Phys.Conf.Ser.(2017)·0 citations
3. 03*

   QCD phase diagram from chiral symmetry restoration: analytic approach at high and low temperature using the Linear Sigma Model with Quarks

   Alejandro Ayala🇲🇽 · Saul Hernandez-Ortiz🇲🇽 · Luis A. Hernandez🇲🇽

   We use the linear sigma model with quarks to study the QCD phase diagram from the point of view of chiral symmetry restoration. We compute the leading order effective potential for high and low temperatures and finite quark chemical potential, up to the contribution of the ring diagrams to account for the plasma screening effects. We fix the values of the model couplings using physical values for the input parameters such as the vacuum pion and sigma masses, the critical temperature at vanishing quark chemical potential and the conjectured end point value of the baryon chemical potential of the transition line at vanishing temperature. We also make the analysis for the same input parameters but with vanishing pion mass. We find that the critical end point (CEP) is located at low temperatures and high quark chemical potentials $(315<{\mu }^{\text{CEP}}<349MeV,18<T^{\text{CEP}}<45MeV)$.

   hep-phnucl-thRev.Mex.Fis.(2018)·28 citations
4. 04*

   Decay behaviors of the $P_c$ hadronic molecules

   C.W. Shen🇨🇳 · Y.H. Lin🇨🇳

   In this proceeding, we present our recent work on decay behaviors of the $P_c$ hadronic molecules, which can help to disentangle the nature of the two $P_c$ pentaquark-like structures. The results turn out that the relative ratio of the decays of $P_c^{+}(4380)$ to ${\bar{D}}^{\ast }{\Lambda }_c$ and $J/\psi p$ is very different for $P_c$ being a ${\bar{D}}^{\ast }{\Sigma }_c$ or $\bar{D}{\Sigma }_c^{\ast }$ bound state with $J^P={\frac{3}{2}}^{-}$. And from the total decay width, we find that $P_c(4380)$ being a $\bar{D}{\Sigma }_c^{\ast }$ molecule state with $J^P={\frac{3}{2}}^{-}$ and $P_c(4450)$ being a ${\bar{D}}^{\ast }{\Sigma }_c$ molecule state with $J^P={\frac{5}{2}}^{+}$ is more favorable to the experimental data.

   hep-phPhys.Part.Nucl.Lett.(2018)·4 citations
5. 05*

   Mass hierarchy and energy scaling of the Tsallis--Pareto parameters in hadron productions at RHIC and LHC energies

   Gábor Bíró🇭🇺 · Gergely Gábor Barnaföldi🇭🇺 · Tamás Sándor Biró🇭🇺 · Keming Shen🇨🇳

   The latest, high-accuracy identified hadron spectra measurements in high-energy nuclear collisions led us to the investigation of the strongly interacting particles and collective effects in small systems. Since microscopical processes result in a statistical Tsallis-Pareto distribution, the fit parameters $q$ and $T$ are well suited for identifying system size scalings and initial conditions. Moreover, parameter values provide information on the deviation from the extensive, Boltzmann-Gibbs statistics in finite-volumes. We apply here the fit procedure developed in our earlier study for proton-proton collisions. The observed mass and $\sqrt{s}$ energy trends in the hadron production are compared to RHIC dAu and LHC pPb data in different centrality/multiplicity classes. Here we present new results on mass hierarchy in pp and pA from light to heavy hadrons.

   hep-phnucl-thEPJ Web Conf.(2018)·22 citations
6. 06*

   Aspects of the same-sign diboson signature from wino pair production with light higgsinos at the high luminosity LHC

   Howard Baer🇺🇸 · Vernon Barger🇺🇸 · James S. Gainer🇺🇸 · Michael Savoy🇺🇸 · Dibyashree Sengupta🇺🇸 · Xerxes Tata🇺🇸

   Naturalness arguments applied to simple supersymmetric (SUSY) theories require a set of light higgsinos with mass $\sim |\mu |$ not too far from $m_h$. These models have an inverted electroweakino spectrum with $|\mu |\ll M_2$ which leads to a rather clean, hadronically quiet, same-sign diboson (SSdB) signature at hadron colliders arising from neutral-plus-charged wino pair production. We improve and expand our earlier studies of this signature for discovering SUSY in natural SUSY models by (i) including backgrounds which were not previously considered and which turn out to be significant, (ii) devising more efficient cuts to successfully contend with these larger backgrounds and determining the discovery reach and exclusion ranges for winos with these cuts, emphasizing projections for the updated integrated luminosity target for HL-LHC of 3 ab${}^{-1}$, and (iii) emphasizing the utility of this channel for natural models without gaugino mass unification. We display the kinematic characteristics of the relatively jet-free same sign dilepton+$/E_T$ events (from leptonic decays of both $W$s) and find that these are only weakly sensitive to the parent wino mass. We also examine the charge asymmetry in these events and show that its measurement can be used to check the consistency of the wino origin of the signal. Finally, we show that -- because the wino branching fractions in natural SUSY are essentially independent of details of the underlying model -- a determination of the rate for clean, same-sign dilepton events yields a better than 10% determination of the wino mass over the entire mass range where experiments at the HL-LHC can discover the wino signal.

   hep-phPRD(2018)·24 citations
7. 07*

   Exotic Quantum States for Charmed Baryons at Finite Temperature

   Jiaxing Zhao🇨🇳 · Pengfei Zhuang🇨🇳

   The significantly screened heavy-quark potential in hot medium provides the possibility to study exotic quantum states of three-heavy-quark systems. By solving the Schrödinger equation for a three-charm-quark system at finite temperature, we found that, there exist Borromean states which might be realized in high energy nuclear collisions, and the binding energies of the system satisfy precisely the scaling law for Efimov states in the resonance limit.

   hep-phPLB(2017)·3 citations
8. 08*

   Scalar and Tensor Glueballs as Gravitons

   Matteo Rinaldi🇪🇸 · Vicente Vento🇪🇸

   The bottom-up approach of the AdS/CFT correspondence leads to the study of field equations in an $Ad{S}_5$ background and from their solutions to the determination of the hadronic mass spectrum. We extend the study to the equations of $Ad{S}_5$ gravitons and determine from them the glueball spectrum. We propose an original presentation of the results which facilitates the comparison of the various models with the spectrum obtained by lattice QCD. This comparison allows to draw some phenomenological conclusions.

   hep-phEPJA(2018)·27 citations
9. 09*

   ${\gamma }_5$ in FDH

   C. Gnendiger🇨🇭 · A. Signer🇨🇭

   We investigate the regularization-scheme dependent treatment of ${\gamma }_5$ in the framework of dimensional regularization, mainly focusing on the four-dimensional helicity scheme (FDH). Evaluating distinctive examples, we find that for one-loop calculations, the recently proposed four-dimensional formulation (FDF) of the FDH scheme constitutes a viable and efficient alternative compared to more traditional approaches. In addition, we extend the considerations to the two-loop level and compute the pseudo-scalar form factors of quarks and gluons in FDH. We provide the necessary operator renormalization and discuss at a practical level how the complexity of intermediate calculational steps can be reduced in an efficient way.

   hep-phPRD(2018)·36 citations
10. 10*

    Signature of heavy sterile neutrinos at CEPC

    Wei Liao🇨🇳 · Xiao-Hong Wu🇨🇳

    We study the production of heavy sterile neutrino $N$, $e^{+}{e}^{-}\to N\nu (\bar{\nu })$, at the Circular Electron Positron Collider(CEPC) and its $ljj$ signal in its decay to three charged fermions. We study background events for this process which are mainly events coming from W pair production. We study the production of a single heavy sterile neutrino and the sensitivity of CEPC to the mixing of sterile neutrino with active neutrinos. We study the production of two degenerate heavy sterile neutrinos in a low energy see-saw model by taking into account the constraints on mixings of sterile neutrinos from the neutrino-less double $\beta$ decay experiment and the masses and mixings of active neutrinos. We show that CEPC under proposal has a good sensitivity to the mixing of sterile neutrinos with active neutrinos for a mass of sterile neutrino around 100 GeV.

    hep-phPRD(2018)·25 citations
11. 11*

    Phenomenology of neutron-antineutron conversion

    Susan Gardner🇺🇸 · Xinshuai Yan🇺🇸

    We consider the possibility of neutron-antineutron ($n-\bar{n}$) conversion, in which the change of a neutron into an antineutron is mediated by an external source, as can occur in a scattering process. We develop the connections between $n-\bar{n}$ conversion and $n-\bar{n}$ oscillation, in which a neutron spontaneously tranforms into an antineutron, noting that if $n-\bar{n}$ oscillation occurs in a theory with B-L violation, then $n-\bar{n}$ conversion can occur also. We show how an experimental limit on $n-\bar{n}$ conversion could connect concretely to a limit on $n-\bar{n}$ oscillation, and vice versa, using effective field theory techniques and baryon matrix elements computed in the M.I.T. bag model.

    hep-phhep-exnucl-exnucl-thPRD(2018)·15 citations
12. 12*

    $W$ boson polarization in vector boson scattering at the LHC

    Alessandro Ballestrero🇮🇹 · Ezio Maina🇮🇹 · Giovanni Pelliccioli🇮🇹

    Measuring the scattering of longitudinally-polarized vector bosons represents a fundamental test of ElectroWeak Symmetry Breaking. In addition to the challenges provided by low rates and large backgrounds, there are conceptual issues which need to be clarified for the definition of a suitable signal. Since vector bosons are unstable and can only be observed through their decay products, the polarization states interfere among themselves. Moreover, already at tree level, there are diagrams which cannot be interpreted as production times decay of EW bosons but are necessary for gauge invariance. We discuss a possible way to define a cross section for polarized $W$'s, dropping all non resonant diagrams, and projecting on shell the resonant ones, thus, preserving gauge invariance. In most cases, the sum of polarized distributions reproduces the full results. In the absence of cuts, the ratios of the polarized cross sections to the full one agree with the results of a standard projection on Legendre polynomials. While the latter cannot be employed in a realistic environment, a comparison of the data with the shapes of the angular distributions for polarized vector bosons allows the extraction of the polarization fractions in the presence of selection cuts on the charged leptons.

    hep-phJHEP(2018)·83 citations
13. 13*

    Neutrino oscillations and Non-Standard Interactions

    Y. Farzan🇮🇷 · M. Tortola🇪🇸

    Current neutrino experiments measure the neutrino mixing parameters with an unprecedented accuracy. The upcoming generation of experiments will be sensitive to subdominant effects that can give information on the unknown neutrino parameters: the Dirac CP-violating phase, the mass ordering and the ${\theta }_{23}$ octant. Determining the exact values of neutrino mass and mixing parameters is crucial to test neutrino models and flavor symmetries. In the first part of this review, we summarize the current status of neutrino oscillation parameters. We consider the most recent data from solar experiments and the atmospheric data from Super-Kamiokande, IceCube and ANTARES. We implement the data from the reactor experiments KamLAND, Daya Bay, RENO and Double Chooz as well as the long baseline data from MINOS, T2K and NOvA. If in addition to the standard interactions, neutrinos have subdominant Non-Standard Interactions (NSI) with matter, extracting the values of these parameters will suffer from new degeneracies. We review such effects and formulate the conditions on the NSI parameters under which the precision measurement of neutrino oscillation parameters can be distorted. Like standard weak interactions, NSI can be categorized into Charged and Neutral Current NSI. Our focus will be on NC NSI since it is possible to build a class of models giving rise to sizeable NC NSI with effects on neutrino oscillations. These models are based on new $U(1)$ gauge symmetry with a boson of mass $\lesssim 10$ MeV. The UV complete model should be electroweak invariant which implies that along with neutrinos, charged fermions acquire new interactions on which there are strong bounds. We enumerate the bounds that exist on such models and show that it is possible to build viable models avoiding all the bounds. We review methods to test these models and suggest approaches to break the degeneracies caused by NSI.

    hep-phhep-exFront.in Phys.(2018)·414 citations
14. 14*

    Compton Scattering of Gamma-Ray Vortex with Laguerre Gaussian Wave Function

    Tomoyuki Maruyama🇯🇵 · Takehito Hayakawa🇯🇵 · Toshitaka Kajino🇯🇵

    In this work, we report calculation for Compton scattering of a gamma-ray vortex with Laguerre Gaussian wave function on an electron in the framework of the relativistic quantum mechanics. We have found the following unexpected feature. The momentum of scattered photon distributes outside of the reaction plane determined by the incident photon and the scattered electron, and hence the energy of the scattered photon also distributes. This novel result indicates that one can identify a gamma-ray vortex by measuring coincidentally the scattered angles of the electron and photon.

    hep-phnucl-thphysics.atom-phphysics.opticsSci.Rep.(2019)·22 citations
15. 15*

    Double Differential High Energy Resummation

    Claudio Muselli🇮🇹

    In this paper we study a general framework to perform leading log high energy resummation with complete dependence from the rapidity and the transverse momentum of the studied system. As an application, high energy resummed expression for the Higgs boson production in the effective field theory framework will be derived. Explicit result for this process will be cross-checked against fixed order evaluations up to NNLO. Consistency with known high energy resummation for single differential rapidity or transverse momentum distribution, as well as for inclusive cross section, will also be shown.

    hep-ph5 citations
16. 16*

    Mono-top Signature from Fermionic Top-partner

    Dorival Goncalves🇺🇸 · Kyoungchul Kong🇺🇸 · Kazuki Sakurai🇵🇱 · Michihisa Takeuchi🇯🇵

    We investigate mono-top signatures arising from phenomenological models of fermionic top-partners, which are degenerate in mass and decay into a bosonic dark matter candidate, either spin-0 or spin-1. Such a model provides a mono-top signature as a smoking-gun, while conventional searches with $t\bar{t}$ + missing transverse momentum are limited. Two such scenarios: i) a phenomenological 3rd generation extra dimensional model with excited top and electroweak sectors, and ii) a model where only a top-partner and a dark matter particle are added to the SM, are studied in the degenerate mass regime. We find that in the case of extra dimension a number of different processes give rise to effectively the same mono-top final state, and a great gain can be obtained in the sensitivity for this channel. We show that the mono-top search can explore top-partner masses up to 630 GeV and 300 GeV for the 3rd generation extra dimensional model and the minimal fermionic top-partner model, respectively, at the high luminosity LHC.

    hep-phhep-exPRD(2018)·5 citations
17. 17*

    Dark Higgs Bosons at FASER

    Jonathan L. Feng🇺🇸 · Iftah Galon🇺🇸 · Felix Kling🇺🇸 · Sebastian Trojanowski🇺🇸

    FASER, ForwArd Search ExpeRiment at the LHC, has been proposed as a small, very far forward detector to discover new, light, weakly-coupled particles. Previous work showed that with a total volume of just $\sim 0.1-1{\mathrm{m}}^3$, FASER can discover dark photons in a large swath of currently unconstrained parameter space, extending the discovery reach of the LHC program. Here we explore FASER's discovery prospects for dark Higgs bosons. These scalar particles are an interesting foil for dark photons, as they probe a different renormalizable portal interaction and are produced dominantly through $B$ and $K$ meson decays, rather than pion decays, leading to less collimated signals. Nevertheless, we find that FASER is also a highly sensitive probe of dark Higgs bosons with significant discovery prospects that are comparable to, and complementary to, much larger proposed experiments.

    hep-phPRD(2018)·149 citations
18. 18*

    Dense baryon matter with isospin and chiral imbalance in the framework of NJL${}_4$ model at large $N_c$: duality between chiral symmetry breaking and charged pion condensation

    T. G. Khunjua🇷🇺 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

    In this paper the phase structure of dense quark matter has been investigated in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of (3+1)-dimensional Nambu--Jona-Lasinio model with two quark flavors. It has been shown that in the large-$N_c$ limit ($N_c$ is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter with isotopic asymmetry.

    hep-phhep-thPRD(2018)·41 citations
19. 19*

    Sensitivity of DUNE to long-baseline neutrino oscillation physics

    Justo Martín-Albo (for the DUNE Collaboration)🇺🇸

    DUNE is an international project, currently in its design phase, for neutrino physics and proton-decay searches. It will consist of two detectors exposed to a megawatt-scale muon neutrino beam that will be produced at Fermilab (Illinois, USA). One detector will record particle interactions near the source of the beam, while a second, much larger, detector comprising four 10-kilotonne liquid argon TPCs will be installed at a depth of 1.5 km at SURF (South Dakota, USA), about 1300 kilometres away of the neutrino source. Among the primary scientific goals of DUNE is the precision measurement of the parameters that govern neutrino mixing, including those still unknown: the octant in which the ${\theta }_{23}$ mixing angle lies, the neutrino mass ordering and the value of the CP violation phase. This paper discusses the sensitivity of the DUNE experiment to these parameters.

    ↳ hep-exhep-phphysics.ins-detPoS(2017)·3 citations
20. 20*

    Proton mass decomposition

    Yi-Bo Yang🇺🇸 · Ying Chen🇨🇳 · Terrence Draper🇺🇸 · Jian Liang🇺🇸 · Keh-Fei Liu🇺🇸

    We report the results on the proton mass decomposition and also on the related quark and glue momentum fractions. The results are based on overlap valence fermions on four ensembles of $N_f=2+1$ DWF configurations with three lattice spacings and volumes, and several pion masses including the physical pion mass. With 1-loop perturbative calculation and proper normalization of the glue operator, we find that the $u,d,$ and $s$ quark masses contribute 9(2)\% to the proton mass. The quark energy and glue field energy contribute 31(5)\% and 37(5)\% respectively in the $\overline{MS}$ scheme at $\mu =2$ GeV. The trace anomaly gives the remaining 23(1)\% contribution. The $u,d,s$ and glue momentum fractions in the $\overline{MS}$ scheme are consistent with the global analysis at $\mu =2$ GeV.

    ↳ hep-lathep-phnucl-thEPJ Web Conf.(2018)·5 citations
21. 21*

    Vacuum fluctuations in an ancestor vacuum: A possible dark energy candidate

    Hajime Aoki🇯🇵 · Satoshi Iso🇯🇵 · Da-Shin Lee🇹🇼 · Yasuhiro Sekino🇯🇵 · Chen-Pin Yeh🇹🇼

    We consider an open universe created by bubble nucleation, and study possible effects of an "ancestor vacuum" (de Sitter space in which bubble nucleation occurred) on the present universe. We compute vacuum expectation values of energy-momentum tensor for a minimally coupled scalar field, carefully taking into account the effect of the ancestor vacuum by the Euclidean prescription. In the study of the time evolution, an important role is played by the so-called supercurvature mode, which is non-normalizable on a spatial slice of open universe and decays in time most slowly. We point out that vacuum energy of a quantum field can be regarded as dark energy if mass of the field is of order the present Hubble parameter or smaller. We obtain preliminary results for the dark energy equation of state w(z) as a function of the redshift.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2018)·4 citations
22. 22*

    Strange matter prospects within the string-flip model

    Niels-Uwe F. Bastian🇵🇱 · David B. Blaschke🇷🇺 · Mateusz Cierniak🇵🇱 · Tobias Fischer🇵🇱 · Mark A. R. Kaltenborn🇺🇸 · Michał Marczenko🇵🇱 · Stefan Typel🇩🇪

    In this contribution we extend the recently developed two-flavor quark-matter string-flip model by including strange quarks. We discuss implications for compact stars.

    ↳ astro-ph.HEhep-phEPJ Web Conf.(2018)·5 citations
23. 23*

    Multi-boson block factorization of fermions

    Leonardo Giusti🇮🇹 · Marco Cè🇩🇪 · Stefan Schaefer🇩🇪

    The numerical computations of many quantities of theoretical and phenomenological interest are plagued by statistical errors which increase exponentially with the distance of the sources in the relevant correlators. Notable examples are baryon masses and matrix elements, the hadronic vacuum polarization and the light-by-light scattering contributions to the muon g-2, and the form factors of semileptonic B decays. Reliable and precise determinations of these quantities are very difficult if not impractical with state-of-the-art standard Monte Carlo integration schemes. I will review a recent proposal for factorizing the fermion determinant in lattice QCD that leads to a local action in the gauge field and in the auxiliary boson fields. Once combined with the corresponding factorization of the quark propagator, it paves the way for multi-level Monte Carlo integration in the presence of fermions opening new perspectives in lattice QCD. Exploratory results on the impact on the above mentioned observables will be presented.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·16 citations
24. 24*

    Extended investigation of the twelve-flavor $\beta$-function

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

    We report new results from high precision analysis of an important BSM gauge theory with twelve massless fermion flavors in the fundamental representation of the SU(3) color gauge group. The range of the renormalized gauge coupling is extended from our earlier work {Fodor:2016zil} to probe the existence of an infrared fixed point (IRFP) in the $\beta$-function reported at two different locations, originally in {Cheng:2014jba} and at a new location in {Hasenfratz:2016dou}. We find no evidence for the IRFP of the $\beta$-function in the extended range of the renormalized gauge coupling, in disagreement with {Cheng:2014jba,Hasenfratz:2016dou}. New arguments to guard the existence of the IRFP remain unconvincing {Hasenfratz:2017mdh}, including recent claims of an IRFP with ten massless fermion flavors {Chiu:2016uui,Chiu:2017kza} which we also rule out. Predictions of the recently completed 5-loop QCD $\beta$-function for general flavor number are discussed in this context.

    ↳ hep-lathep-phPLB(2018)·47 citations
25. 25*

    Nucleon matter equation of state, particle number fluctuations, and shear viscosity within UrQMD box calculations

    A. Motornenko🇩🇪 · L. Bravina🇳🇴 · M. I. Gorenstein🇺🇦 · A. G. Magner🇺🇦 · E. Zabrodin🇳🇴

    Properties of equilibrated nucleon system are studied within the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport model. The UrQMD calculations are done within a finite box with periodic boundary conditions. The system achieves thermal equilibrium due to nucleon-nucleon elastic scattering. For the UrQMD equilibrium state, nucleon energy spectra, equation of state, particle number fluctuations, and shear viscosity $\eta$ are calculated. The UrQMD results are compared with both, statistical mechanics and Chapman-Enskog kinetic theory, for a classical system of nucleons with hard-core repulsion.

    ↳ nucl-thhep-phJ.Phys.G(2018)·7 citations
26. 26*

    Light-by-light forward scattering amplitudes in Lattice QCD

    Antoine Gerardin🇩🇪 · Jeremy Green🇩🇪 · Oleksii Gryniuk🇩🇪 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Vladimir Pascalutsa🇩🇪 · Hartmut Wittig🇩🇪

    We present our preliminary results on the calculation of hadronic light-by-light forward scattering amplitudes using vector four-point correlation functions computed on the lattice. Using a dispersive approach, forward scattering amplitudes can be described by ${\gamma }^{\ast }{\gamma }^{\ast }\to$ hadrons fusion cross sections and then compared with phenomenology. We show that only a few states are needed to reproduce our data. In particular, the sum rules considered in this study imply relations between meson$-\gamma \gamma$ couplings and provide valuable information about individual form factors which are often used to estimate the meson-pole contributions to the hadronic light-by-light contribution to the $(g-2)$ of the muon.

    ↳ hep-lathep-phEPJ Web Conf.(2018)·1 citation
27. 27*

    Composite graviton self-interactions in a model of emergent gravity

    Christopher D. Carone🇺🇸 · Tangereen V. B. Claringbold🇺🇸 · Diana Vaman🇺🇸

    We consider a theory of scalars minimally coupled to an auxiliary background metric. The theory is generally covariant and subject to the constraint of vanishing energy-momentum tensor. Eliminating the auxiliary metric leads to a reparametrization invariant, non-polynomial, metric-independent action for the scalar fields. Working in the limit of a large number of physical scalars, a composite massless spin-2 state, the graviton, was identified in previous work, in a two-into-two scalar scattering process. Here, we further explore the possibility that dynamical emergent gravity is a natural feature of generally covariant quantum field theories, by studying the self-interactions of the emergent composite graviton. We show that the fine-tuning previously imposed to ensure the vanishing of the cosmological constant, as well as the existence of the massless spin-2 state, also assures that the emergent graviton's cubic self-interactions are consistent with those of Einstein's general relativity, up to higher-derivative corrections. We also demonstrate in a theory with more than one type of scalar that the composite graviton coupling is universal.

    ↳ hep-thgr-qchep-phPRD(2018)·16 citations
28. 28*

    Feynman integrals as flat bundles over the complement of Landau varieties

    Stanislav Srednyak🇺🇸

    We demonstrate that Feynman integrals of a fixed diagram form a flat vector bundle over the complement of Landau varieties that possesses a connection \begin{equation} \frac{\partial}{\partial p_{i,\mu}}f_\beta(p_{i,\mu})=\sum_{\beta'} \sum_k \sum_{I_1,...,I_k} \frac{A^{I_1,...,I_k}_{i,\mu,\beta,\beta'}(p)}{L_{I_1}(p)...L_{I_k}(p)} f_{\beta'}(p) \end{equation} where $L_I(p)$ are the Landau polynomials (multidiscriminants). This is the Gauss-Manin connection for the original integral. This result suggests a shift of focus from the integrals to the geometry of the complement of Landau varieties and Riemann-Hilbert data associated with these varieties.

    ↳ math-phhep-phmath.AGmath.MP1 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.