Mon·Dec 16, 2019Monday·December 16, 2019

1. 01*

   Leading Two-loop corrections to the mass of Higgs boson in the High scale Dirac gaugino supersymmetry

   Di Liu🇺🇸

   Precision measurements of the Higgs mass have become a powerful constraint on models of physics beyond the standard model. We revisit supersymmetric models with Dirac gauginos and study the contributions to the Higgs mass. We calculate the leading two-loop corrections to the SM-like Higgs mass by constructing a series of EFTs and iteratively integrating out heavy particles. We then apply these calculations to a variety of scenarios, including a simple Dirac gluino, and split Dirac models of supersymmetry. We present the detailed formulae for threshold corrections and compare with previous results, where available. In general, the contributions are small, but the additional precision allows us to make more concrete statements about the relevant scales in Dirac SUSY models.

   hep-ph7 citations
2. 02*

   Precise ${\alpha }_s$ determination from charmonium sum rules

   Diogo Boito🇧🇷 · Vicent Mateu🇪🇸

   The strong coupling, ${\alpha }_s$, governs perturbative Quantum Chromodynamics (QCD) and is one of the free parameters of the Standard Model. We introduce a new method that allows a precise extraction of ${\alpha }_s(m_Z)$ from dimensionless ratios of roots of moments of the charm-quark vector correlator. The ratios we use in our analysis have a rather weak logarithmic quark-mass dependence, starting at $\mathcal{O}({\alpha }_s^2)$, and can be obtained from experimental data with good precision, since they benefit from positive correlations among the individual experimentally determined moments. We perform a careful and conservative error analysis with special emphasis on uncertainties related to the truncation of perturbation theory, treating the renormalization scales such as to ensure order-by-order convergence. Our final result, with expressions at $\mathcal{O}({\alpha }_s^3)$, is ${\alpha }_s(m_Z)=0.1168\pm 0.0019$.

   hep-phhep-latPLB(2020)·23 citations
3. 03*

   Two-Loop QCD Helicity Amplitudes for Higgs Production Associated with a Vector Boson through Bottom Quark Annihilation

   Taushif Ahmed · A. H. Ajjath · Long Chen🇩🇪 · Prasanna K. Dhani🇮🇹 · Pooja Mukherjee🇮🇳 · V. Ravindran🇮🇳

   We present the two-loop QCD corrections to the amplitude of the Higgs production associated with a $Z$ boson via the bottom quark-antiquark annihilation channel with a non-vanishing bottom-quark Yukawa coupling. The computation is performed by projecting the D-dimensional scattering amplitude directly onto a set of Lorentz structures related to the linear polarisation states of the $Z$ boson. We cross-check the finite remainders through a computation based on conventional form factor decomposition. We show that for physical observables, an ultimate D-dimensional form factor decomposition of amplitudes is not necessary which has a huge potential to simplify a multiloop computation. We compute numerically the resulting cross sections under the soft-virtual approximation to NNLO and find it three orders of magnitude smaller than that of the s-channel.

   hep-phhep-thPoS(2019)·1 citation
4. 04*

   Sigmoidal Inflation

   E. Díaz🇨🇦 · O. Meza-Aldama🇲🇽

   In this paper we present a new cosmological inflationary model which is constructed using the Ivanov-Salopek-Bond method with a logistic generating function. We derive the inflationary observables as well as the duration and temperature of the subsequent reheating epoch of our model exactly, with no need to recur to the slow roll approximation. The obtained scalar spectral index and tensor-to-scalar ratio of perturbations fall comfortably within the range of the measurements presented by the Planck collaboration. On the other hand, for the reheating era, our model predicts a relatively small number of e-folds and thus high temperatures, still within range of Planck's bounds.

   hep-phastro-ph.COJ.Phys.Comm.(2020)·2 citations
5. 05*

   LHC constraints on $W^{\prime },Z^{\prime }$ that couple mainly to third generation fermions

   Alper Hayreter🇹🇷 · Xiao-Gang He🇹🇼 · German Valencia🇦🇺

   We use the results of CMS and ATLAS searches for resonances that decay to $\tau \nu$ or $tb$ and ${\tau }^{+}{\tau }^{-}$ or $t\bar{t}$ final states to constrain the parameters of non-universal $W^{\prime }$ and $Z^{\prime }$ gauge bosons that couple preferentially to the third generation. For the former we consider production from $c\bar{b}$ annihilation and find very weak constraints on the strength of the interaction and only for the mass range between 800 and 1100 GeV from the $pp\to {\tau }_h{p}_T^{\mathrm{miss}}$ channel. The constraints on the latter are much stronger and arise from both $t\bar{t}$ and ${\tau }^{+}{\tau }^{-}$ production. Treated separately, we find that the weak constraints on the $W^{\prime }$ still permit an explanation of the $R(D^{(\star )})$ anomalies with a light sterile neutrino whereas the stronger constraints on the $Z^{\prime }$ exclude significant light sterile neutrino contributions to the $K\to \pi \nu \bar{\nu }$ rates. Within specific models the masses of $W^{\prime }$ and $Z^{\prime }$ are of course related and we briefly discuss the consequences.

   hep-phEPJC(2020)·13 citations
6. 06*

   Interference effects in dilepton resonance searches for Z' bosons and dark matter mediators

   Felix Kahlhoefer🇩🇪 · Alexander Mück🇩🇪 · Stefan Schulte🇩🇪 · Patrick Tunney🇩🇪

   New Z' gauge bosons arise in many extensions of the Standard Model and predict resonances in the dilepton invariant mass spectrum. Searches for such resonances therefore provide important constraints on many models of new physics, but the resulting bounds are often calculated without interference effects. In this work we show that the effect of interference is significant and cannot be neglected whenever the Z' width is large (for example because of an invisible contribution). To illustrate this point, we implement and validate the most recent 139 fb${}^{-1}$ dilepton search from ATLAS and obtain exclusion limits on general Z' models as well as on simplified dark matter models with spin-1 mediators. We find that interference can substantially strengthen the bound on the Z' couplings and push exclusion limits for dark matter simplified models to higher values of the Z' mass. Together with this study we release the open-source code ZPEED, which provides fast likelihoods and exclusion bounds for general Z' models.

   hep-phhep-exJHEP(2020)·19 citations
7. 07*

   Gravitational transition form factors of $N(1535)\to N$

   U. Özdem🇹🇷 · K. Azizi🇮🇷

   We employ the quark part of the symmetric energy-momentum tensor current to calculate the transition gravitational form factors of the $N(1535)\to N$ by means of the light cone QCD sum rule formalism. In numerical analysis, we use two different sets of the shape parameters in the distribution amplitudes of the $N(1535)$ baryon and the general form of the nucleon's interpolating current. It is seen that the momentum squared dependence of the gravitational form factors can be well described by the p-pole fit function. The results obtained by using two sets of parameters are found to be quite different from each other and the $N(1535)\to N$ transition gravitational form factors depend highly on the shape parameters of the distribution amplitudes of the $N(1535)$ state that parametrize relative orbital angular momentum of the constituent quarks.

   hep-phhep-exhep-latPRD(2020)·20 citations
8. 08*

   Tree-level splitting amplitudes for a quark into four collinear partons

   Vittorio Del Duca🇨🇭 · Claude Duhr🇨🇭 · Rayan Haindl🇨🇭 · Achilleas Lazopoulos🇨🇭 · Martin Michel🇧🇪

   We compute in conventional dimensional regularisation the tree-level splitting amplitudes for a quark parent in the limit where four partons become collinear to each other. This is part of the universal infrared behaviour of the QCD scattering amplitudes at next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$) in the strong coupling constant. Further, we consider the iterated limit when $m^{\prime }$ massless partons become collinear to each other within a bigger set of $m$ collinear partons, as well as the limits when one gluon or a $q\bar{q}$ pair or two gluons become soft within a set of $m$ collinear partons.

   hep-phJHEP(2020)·44 citations
9. 09*

   The effect of an anomalous Higgs trilinear self-coupling on the h to gamma Z decay

   G. Degrassi🇮🇹 · M. Vitti🇮🇹

   We compute the two-loop effects induced by an anomalous Higgs trilinear self-coupling in the partial decay width h to gamma Z. The computation is performed using the anomalous coupling approach working in the unitary gauge and in a theory in which the anomalous coupling is generated via the addition to the scalar potential part of the Standard Model Lagrangian of an (in)finite tower of (Phi^dagger Phi)^n terms. The former computation is automatically finite while the latter requires the renormalization of the lowest order contribution. We discuss the renormalization conditions that should be employed in order to obtain the same result in the two approaches. We find that the h to gamma Z process is one of the most sensitive mode to an anomalous trilinear Higgs self-coupling. As a by-product of this work we confirm one of two different results present in the literature concerning the contribution of an anomalous Higgs trilinear coupling in the h to gamma gamma decay.

   hep-phhep-exEPJC(2020)·25 citations
10. 10*

    Lifetime and dominant decay modes of the tetraquark with double beauty $bb\bar{u}\bar{d}$

    J-M. Richard🇫🇷 · E. Hernández🇪🇸 · A. Valcarce🇪🇸 · J. Vijande🇪🇸

    We briefly review the stability of the $QQ\bar{q}\bar{q}$-type of tetraquarks with two heavy quarks and two light antiquarks. We present the first comprehensive estimate of the lifetime and leading decay modes of the exotic meson $bb\bar{u}\bar{d}$ with double beauty.

    hep-phhep-ex0 citations
11. 11*

    Exclusive production of $\varphi$ meson in the ${\gamma }^{\ast }p\to \varphi p$ reaction at large photon virtualities within $k_T$-factorization approach

    A.D. Bolognino🇮🇹 · A. Szczurek🇵🇱 · W. Schäfer🇵🇱

    We apply the $k_T$-factorization approach to the production of $\varphi$ meson in deep-inelastic scattering. The helicity-conserving ${\gamma }^{\ast }(T,L)\to \varphi$ impact factor is calculated for longitudinal and transverse photon polarization using $\varphi$ meson distribution amplitudes. Different unintegrated gluon distributions are used in the calculations. The formalism for massless quarks/antiquarks gives too large transverse and longitudinal cross sections for photon virtualities below $Q^2\sim 8{\mathrm{GeV}}^2$. We suggest how to improve the description of the HERA data by introducing effective strange quark masses into the formalism. We derive the corresponding massive impact factor by comparing to the light-cone wave function representation used in previous $k_T$-factorization calculations and the color-dipole approaches. As a byproduct we present expressions for higher twist-amplitudes as weighted integrals over the light-cone wave function. The quark mass $m_q\approx 0.5$ GeV allows to improve the description of both longitudinal and transverse cross section down to $Q^2\sim$ 4 GeV${}^2$. We present also the polarized cross section ratio ${\sigma }_L/{\sigma }_T$ and the behavior of the total cross section ${\sigma }_{tot}={\sigma }_L+{\sigma }_T$ as a function of photon virtuality.

    hep-phPRD(2020)·75 citations
12. 12*

    Non-perturbative structure of semi-inclusive deep-inelastic and Drell-Yan scattering at small transverse momentum

    Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇩🇪

    We consider semi-inclusive deep inelastic scattering (SIDIS) and Drell-Yan events within transverse momentum dependent (TMD) factorization. Based on the simultaneous fit of multiple data points, we extract the unpolarized TMD distributions and the non-perturbative evolution kernel. The high quality of the fit confirms a complete universality of TMD non-perturbative distributions. The extraction is supplemented by phenomenological analyses of various parts of the TMD factorization, such as sensitivity to non-perturbative parameterizations, perturbative orders, collinear distributions, correlations between parameters, and others.

    hep-phJHEP(2020)·273 citations
13. 13*

    Master integrals for all unitarity cuts of massless four-loop propagators

    Vitaly Magerya🇩🇪 · Andrey Pikelner🇷🇺

    Among the unitarity cuts of massless 4-loop propagators two classes have remained unknown until recently: 2-loop 3-particle cuts, and 1-loop 4-particle cuts. In this article we shall discuss the calculation that completes the master integrals for these cuts: both the motivation and the methods (including dimensional recurrence relations and direct integration at higher space-time dimensions).

    hep-phPoS(2019)·1 citation
14. 14*

    Access to decoupled information on Generalized Parton Distributions (GPDs) via Double Deeply Virtual Compton Scattering (DDVCS)

    Shengying Zhao🇫🇷

    The Generalized Parton Distributions (GPDs) constitute an appropriate framework for a universal description of the partonic structure of the nucleon. Double Deeply Virtual Compton Scattering (DDVCS) process provides the only experimental way to measure independently the dependences of the GPDs on the average and transferred momentum. This proceeding discusses the feasibility of a DDVCS experiment in the context of JLab 12 GeV, model-predicted pseudo-data, and extraction of the relevant GPDs information based on a fitter algorithm.

    hep-phnucl-ex1 citation
15. 15*

    Double field inflation of generalized dilaton-axion models with a new Fayet-Iliopoulos (FI) term

    Man Ping Kwan Ellgan🇯🇵

    We study the inflation dynamics of generalized dilaton-axion models with a new Fayet-Iliopoulos (FI) term. In particular, we find the relationships between the super-potential parameters and the coefficient of natural logarithm of the real part of dilaton-axion fields stored in the Kähler potential based on the vacuum conditions at the end of inflation. We also evaluate the feasible initial field values, their corresponding SUSY breaking scales and the iso-curvature parameters.

    hep-ph1 citation
16. 16*

    A light dilaton at the LHC

    Aqeel Ahmed🇧🇪 · Alberto Mariotti🇧🇪 · Saereh Najjari🇧🇪

    In this paper, we explore the possibility that a light dilaton can be the first sign of new physics at the LHC. The dilaton could emerge in approximate scale invariant UV completions of the SM as the Goldstone boson associated with the spontaneous breaking of the scale invariance. We study in detail the phenomenology of the dilaton at the LHC in the mass range of [$10-300$] GeV including the case where the dilaton can mix with the SM Higgs boson, leading to an interesting interplay between direct and indirect constraints. A possibility that the dilaton acts as a portal to a dark sector is also considered. As a minimal realization, the dark sector includes a dark photon lighter than the dilaton implying sizeable missing energy signatures. Several simplified benchmark models that can encode different UV completions are discussed, for which we scrutinize the current and future LHC reach.

    hep-phJHEP(2020)·28 citations
17. 17*

    Signatures of microscopic black holes and extra dimensions at future neutrino telescopes

    Katherine J. Mack🇺🇸 · Ningqiang Song🇨🇦 · Aaron C. Vincent🇨🇦

    In scenarios with large extra dimensions (LEDs), the fundamental Planck scale can be low enough that collisions between high-energy particles may produce microscopic black holes. High-energy cosmic neutrinos can carry energies much larger than a PeV, opening the door to a higher energy range than Earth-based colliders. Here, for the first time, we identify a number of unique signatures of microscopic black holes as they would appear in the next generation of large-scale neutrino observatories such as IceCube-Gen2 and the Pacific Ocean Neutrino Explorer. These signatures include new event topologies, energy distributions, and unusual ratios of hadronic-to-electronic energy deposition, visible through Cherenkov light echos due to delayed neutron recombination. We find that the next generation of neutrino telescopes can probe LEDs with a Planck scale up to 6 TeV, though the identification of unique topologies could push their reach even further.

    hep-phJHEP(2020)·23 citations
18. 18*

    Measuring the Weak Mixing Angle in the DUNE Near Detector Complex

    André de Gouvêa🇺🇸 · Pedro A. N. Machado🇺🇸 · Yuber F. Perez-Gonzalez🇺🇸 · Zahra Tabrizi🇧🇷

    The planned DUNE experiment will have excellent sensitivity to the vector and axial couplings of the electron to the $Z$-boson via precision measurements of neutrino--electron scattering. We investigate the sensitivity of DUNE-PRISM, a movable near detector in the direction perpendicular to the beam line, and find that it will qualitatively impact our ability to constrain the weak couplings of the electron. We translate these neutrino--electron scattering measurements into a determination of the weak mixing angle at low scales and estimate that, with seven years of data taking, the DUNE near-detector can be used to measure ${\sin }^2{\theta }_W$ with about 2\% precision. We also discuss the impact of combining neutrino--electron scattering data with neutrino trident production at DUNE-PRISM.

    hep-phhep-exPRL(2020)·47 citations
19. 19*

    A testable hidden-sector model for Dark Matter and neutrino masses

    Julia Gehrlein🇺🇸 · Mathias Pierre🇪🇸

    We consider a minimal extension of the Standard Model with a hidden sector charged under a dark local $U(1{)}^{\prime }$ gauge group, accounting simultaneously for light neutrino masses and the observed Dark Matter relic abundance. The model contains two copies of right-handed neutrinos which give rise to light neutrino-masses via an extended seesaw mechanism. The presence of a stable Dark-Matter candidate and a massless state naturally arise by requiring the simplest anomaly-free particle content without introducing any extra symmetries. We investigate the phenomenology of the hidden sector considering the $U(1{)}^{\prime }$ breaking scale of the order of the electroweak scale. Confronting the thermal history of this hidden-sector model with existing and future constraints from collider, direct and indirect detection experiments provides various possibilities of probing the model in complementary ways as every particle of the dark sector plays a specific cosmological role. Across the identified viable parameter space, a large region predicts a sizable contribution to the effective relativistic degrees-of-freedom in the early Universe that allows to alleviate the recently reported tension between late and early measurements of the Hubble constant.

    hep-phastro-ph.COJHEP(2020)·28 citations
20. 20*

    Drawing insights from pion parton distributions

    Minghui Ding🇨🇳 · Khépani Raya🇲🇽 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

    A symmetry-preserving continuum approach to the two valence-body bound-state problem is used to calculate the valence, glue and sea distributions within the pion; unifying them with, inter alia, electromagnetic pion elastic and transition form factors. The analysis reveals the following momentum fractions at the scale ${\zeta }_2:=2$GeV: $⟨x_{\mathrm{valence}}⟩=0.48(3)$, $⟨x_{\mathrm{glue}}⟩=0.41(2)$, $⟨x_{\mathrm{sea}}⟩=0.11(2)$; and despite hardening induced by the emergent phenomenon of dynamical chiral symmetry breaking, the valence-quark distribution function, $q^{\pi }(x)$, exhibits the $x\simeq 1$ behaviour predicted by quantum chromodynamics (QCD). After evolution to $\zeta =5.2$GeV, the prediction for $q^{\pi }(x)$ matches that obtained using lattice-regularised QCD. This confluence should both stimulate improved analyses of existing data and aid in planning efforts to obtain new data on the pion distribution functions.

    hep-phhep-exhep-latnucl-ex+1CPC(2020)·55 citations
21. 21*

    Measuring the skewness dependency of Generalized Parton Distributions

    Shengying Zhao🇫🇷 · Eric Voutier🇫🇷

    Generalized Parton Distributions (GPDs) have emerged over the 1990s as a powerful concept and tool to study nucleon structure. They provide nucleon tomography from the correlation between transverse position and longitudinal momentum of partons. The Double Deeply Virtual Compton Scattering (DDVCS) process consists of the Deeply Virtual Compton Scattering (DVCS) process with a virtual photon in the final state eventually generating a lepton pair, which can be either an electron-positron or a muon-antimuon pair. The virtuality of the final time-like photon can be measured and varied, thus providing an extra lever arm and allowing one to measure the GPDs for the initial and transferred momentum dependences independently. This unique feature of DDVCS is of relevance, among others, for the determination of the distribution of nuclear forces which is accessed through the skewness dependency of GPDs. This proceeding discusses the feasibility and merits of a DDVCS experiment in the context of JLab 12 GeV based on model-predicted pseudo-data and the capability of extraction of Compton Form Factors based on a fitter algorithm.

    hep-phnucl-exJ.Phys.Conf.Ser.(2020)·2 citations
22. 22*

    A new renormalon in two dimensions

    Marcos Marino🇨🇭 · Tomas Reis🇨🇭

    According to standard lore, perturbative series of super-renormalizable theories have only instanton singularities. In this paper we show that two-dimensional scalar theories with a spontaneously broken $O(N)$ symmetry at the classical level, which are super-renormalizable, have an IR renormalon singularity at large $N$. Since perturbative expansions in these theories are made around the "false vacuum" in which the global symmetry is broken, this singularity can be regarded as a manifestation of the non-perturbative absence of Goldstone bosons. We conjecture that the Borel singularity in the ground state energy of the Lieb--Liniger model is a non-relativistic manifestation of this phenomenon. We also provide {\it en passant} a detailed perturbative calculation of the Lieb--Liniger energy up to two-loops, and we check that it agrees with the prediction of the Bethe ansatz.

    ↳ hep-thcond-mat.quant-gashep-lathep-phJHEP(2020)·30 citations
23. 23*

    Effective viscosities in a hydrodynamically expanding boost-invariant QCD plasma

    Jean-François Paquet🇺🇸 · Steffen A. Bass🇺🇸

    Background: The near-equilibrium properties of a QCD plasma can be encoded into transport coefficients such as bulk and shear viscosity. In QCD, the ratio of these transport coefficients to entropy density, $\zeta /s$ and $\eta /s$, depends non-trivially on the plasma's temperature. Purpose: We show that in a 0+1D boost-invariant fluid, a temperature-dependent $\zeta /s(T)$ or $\eta /s(T)$ can be described by an equivalent effective viscosity ${⟨\zeta /s⟩}_{\text{eff}}$ or ${⟨\eta /s⟩}_{\text{eff}}$. We extend the concept of effective viscosity in systems with transverse expansion, and discuss how effective viscosities can be used to identify families of $\zeta /s(T)$ and $\eta /s(T)$ that lead to similar hydrodynamic evolution. Results: In 0+1D, the effective viscosity is expressed as a simple integral of $\zeta /s(T)$ or $\eta /s(T)$ over temperature, with a weight determined by the speed of sound of the fluid. The result is general for any equation of state with a moderate temperature dependence of the speed of sound, including the QCD equation of state. In 1+1D, a similar definition of effective viscosity is obtained in terms of characteristic trajectories in time and transverse direction. This leads to an infinite number of constraints on an infinite functional space for $\zeta /s(T)$ and $\eta /s(T)$. Conclusions: The definition of effective viscosity in a 0+1D system clarifies how infinite families of $\zeta /s(T)$ and $\eta /s(T)$ can result in nearly identical hydrodynamic temperature profiles. By extending the study to a boost-invariant cylindrical (1+1D) fluid, we identify an approximate but more general definition of effective viscosity that highlight the potential and limits of the concept of effective viscosity in fluids with limited symmetries.

    ↳ nucl-thhep-phPRC(2020)·7 citations
24. 24*

    Supernovae and photon frequency shift induced by the Standard-Model Extension

    Alessandro D.A.M. Spallicci🇫🇷 · Fabio Ragosta🇮🇹 · José A. Helayël-Neto🇧🇷 · Martín López-Corredoira🇪🇸

    We revisit for 714 SNeIa the discrepancy between the red-shift associated to the distance modulus $\mu$ and the spectroscopic red-shift. Previous work has shown that the total red-shift $z$ might be a combination of the expansion red-shift $z_{\mathrm{C}}$ and of a static, blue or red shift $z_{\mathrm{LSV}}(r)$, $r$ being the comoving distance. The latter is due to the energy non-conservation of the photon propagating through Electro-Magnetic (EM) background fields (host galaxy, intergalactic and Milky Way), under Lorentz(-Poincaré) Symmetry Violation (LSV), associated to the Standard-Model Extension (SME). The non-conservation stems from the vacuum expectation value of the vector and tensor LSV fields. For zero radiation ${\Omega }_{\mathrm{rad}}$ and curvature ${\Omega }_{\mathrm{k}}$ densities, and matter density ${\Omega }_m=0.28$, the SN1a positions in the ($\mu$, z) plan are recovered according to the different strengths, orientations, alignments and space-time dependencies of the EM fields and LSV components. The LSV vacuum energy may be thus tantamount to ${\Omega }_{\Lambda }\simeq 0.7$, but unrelated to an accelerated expansion. We present models with red or blue-shifts $z_{\mathrm{LSV}}$, below $10\%$ of $z$. The $\nu$ frequency variation is below $10^{-19}\Delta \nu /\nu$ per m.

    ↳ astro-ph.COgr-qchep-ph0 citations
25. 25*

    Capturing non-exponential dynamics in the presence of two decay channels

    Francesco Giacosa🇵🇱 · Przemysław Kościk🇵🇱 · Tomasz Sowiński🇵🇱

    The most unstable quantum states and elementary particles possess more than a single decay channel. At the same time, it is well known that typically the decay law is not simply exponential. Therefore, it is natural to ask how to spot the non-exponential decay when (at least) two decay channels are opened. In this work, we study the tunneling phenomenon of an initially localized particle in two spatially opposite directions through two different barriers, mimicking two decay channels. In this framework, through a specific quantum mechanical examples which can be accurately solved, we study general properties of a two-channel decay that apply for various unstable quantum states (among which also for unstable particles). Apart from small deviations at early times, the survival probability and the partial tunneling probability along the chosen direction are very well described by the exponential-decay model. In contrast, the ratios of the decay probabilities and probability currents are evidently not a simple constant (as they would be in the exponential limit) but display time-persisting oscillations. Hence, these ratios are optimal witnesses of deviations from the exponential decay law.

    ↳ quant-phhep-phPRA(2020)·12 citations
26. 26*

    Sp(4) gauge theories on the lattice: Quenched fundamental and antisymmetric fermions

    Ed Bennett🇬🇧 · Deog Ki Hong🇰🇷 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Michele Mesiti🇬🇧 · Maurizio Piai🇬🇧 · Jarno Rantaharju🇫🇮 · Davide Vadacchino🇮🇹

    We perform lattice studies of meson mass spectra and decay constants of the $Sp(4)$ gauge theory in the quenched approximation. We consider two species of (Dirac) fermions as matter field content, transforming in the 2-index antisymmetric and the fundamental representation of the gauge group, respectively. All matter fields are formulated as Wilson fermions. We extrapolate to the continuum and massless limits, and compare to each other the results obtained for the two species of mesons. In the case of two fundamental and three antisymmetric fermions, the long-distance dynamics is relevant for composite Higgs models. This is the first lattice study of this class of theories. The global $SU(4)\times SU(6)$ symmetry is broken to the $Sp(4)\times SO(6)$ subgroup, and the condensates align with the explicit mass terms present in the lattice formulation of the theory. The main results of our quenched calculations are that, with fermions in the 2-index antisymmetric representation of the group, the masses squared and decay constant squared of all the mesons we considered are larger than the corresponding quantities for the fundamental representation, by factors that vary between $\sim$1.2 and $\sim$2.7. We also present technical results that will be useful for future lattice investigations of dynamical simulations, of composite chimera baryons, and of the approach to large $N$ in the $Sp(2N)$ theories considered. We briefly discuss their high-temperature behaviour, where symmetry restoration and enhancement are expected.

    ↳ hep-lathep-phPRD(2020)·91 citations
27. 27*

    The ILC as a natural SUSY discovery machine and precision microscope: from light higgsinos to tests of unification

    Howard Baer🇺🇸 · Mikael Berggren🇩🇪 · Keisuke Fujii🇯🇵 · Jenny List🇩🇪 · Suvi-Leena Lehtinen🇩🇪 · Tomohiko Tanabe🇯🇵 · Jacqueline Yan🇯🇵

    The requirement of electroweak naturalness in simple supersymmetric models implies the existence of a cluster of four light higgsinos with mass $\sim 100-300$\,GeV, the lighter the better. While such light compressed spectra may be challenging to observe at LHC, the International Linear $e^{+}{e}^{-}$ Collider (ILC) with $\sqrt{s}>2m_{\mathrm{higgsino}}$ would serve as both a SUSY discovery machine and a precision microscope. We study higgsino pair production signatures at the ILC based on full, \texttt{Geant4-}based simulation of the ILD detector concept. We examine several benchmark scenarios that may be challenging for discovery at HL-LHC due to mass differences between the higgsino states between $20$ and $4$\,GeV. Assuming $\sqrt{s}=500$\,GeV and 1000\,fb${}^{-1}$ of integrated luminosity, the individual higgsino masses can be measured to $1-2\%$ precision in case of the larger mass differences, and at the level of $5\%$ for the smallest mass difference case. The higgsino mass splittings are sensitive to the electroweak gaugino masses and allow extraction of gaugino masses to $\sim 3-20\%$ (depending on the model). Extrapolation of gaugino masses via renormalization group running can test the hypothesis of gaugino mass unification. We also examine a case with natural generalized mirage mediation where the unification of gaugino masses at an intermediate scale apparently gives rise to a natural SUSY spectrum somewhat beyond the reach of HL-LHC.

    ↳ hep-exhep-phPRD(2020)·33 citations
28. 28*

    New Quantum Phase of the Universe before Inflation and its Cosmological and Dark Energy Implications

    Norma G. Sanchez (CNRS, LERMA PSL Univ Observatoire de Paris, Sorbonne Univ)🇫🇷

    The physical history of the Universe is completed by including the quantum planckian and trans-planckian phase before Inflation in the Standard Model of the Universe in agreement with observations. A new quantum precursor phase appears beyond the Planck scale. We extend de Sitter universe to the quantum domain: classical-quantum de Sitter duality. As a result: The classical and quantum dual de Sitter Temperatures and Entropies are naturally included, and the different (classical, semiclassical, quantum planckian and super-planckian) de Sitter regimes characterized in a precise and unifying way. Relevant cosmological examples as Inflation and Dark Energy are described. This allows to find in a simple and consistent way: Quantum Inflationary spectra and their CMB observables, including in particular the classical known Inflation spectra and the quantum corrections to them. A unifying picture for the Universe epochs and their quantum precursors emerges with the cosmological constant as the vacuum energy, entropy and temperature of the Universe, shedding light into the cosmological constant problem (Abridged).

    ↳ gr-qcastro-ph.COhep-phhep-thInt.J.Mod.Phys.A(2019)·11 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.