We present the first public version of Caravel, a C++17 framework for the computation of multi-loop scattering amplitudes in quantum field theory, based on the numerical unitarity method. Caravel is ...composed of modules for the D-dimensional decomposition of integrands of scattering amplitudes into master and surface terms, the computation of tree-level amplitudes in floating point or finite-field arithmetic, the numerical computation of one- and two-loop amplitudes in QCD and Einstein gravity, and functional reconstruction tools. We provide programs that showcase Caravel's main functionalities and allow to compute selected one- and two-loop amplitudes.
Program Title:Caravel
CPC Library link to program files:https://doi.org/10.17632/rfjrxrb3rk.1
Developer's repository link:https://gitlab.com/caravel-public/caravel.git
Licensing provisions: GPLv3
Programming language: C++
External dependencies:
• Required:Python3 1, meson 2
• Optional:Doxygen 3, Eigen 4, GiNaC 5, GMP 6, Lapack 7, MPFR 8, MPI 9, PentagonLibrary 10,11, QD 12
Nature of problem: The computation of multi-loop multi-particle scattering amplitudes in quantum field theory
Solution method: The multi-loop numerical unitarity method, functional reconstruction algorithms
Additional comments including restrictions and unusual features: Current version includes tools employed in previous calculations, with the aim of showcasing details of the algorithms employed. Computations are organized by provided data files.
1http://www.python.org/2https://mesonbuild.com/3http://www.doxygen.nl/4http://eigen.tuxfamily.org/5https://ginac.de/6https://gmplib.org/7http://www.netlib.org/lapack/8https://www.mpfr.org/9https://www.open-mpi.org/10T. Gehrmann, J. M. Henn and N. A. Lo Presti, JHEP 1810 (2018) 103, arXiv:1807.09812 hep-ph11https://gitlab.com/caravel-public/pentagon-library12QD: A double-double and quad-double package for Fortran and C++, https://www.davidhbailey.com/dhbsoftware/
A model of muon anomalies Greljo, Admir; Stangl, Peter; Eller Thomsen, Anders
Physics letters. B,
09/2021, Volume:
820
Journal Article
Peer reviewed
Open access
The Standard Model (SM) is augmented with a U(1)B−3Lμ gauge symmetry spontaneously broken above the TeV scale when an SM-singlet scalar condenses. Scalar leptoquarks S1(3)=(3‾,1(3),13) charged under ...U(1)B−3Lμ mediate the intriguing effects observed in muon (g−2), RK(⁎), and b→sμ+μ− angular distributions, while generically evading all other phenomenological constraints. The fermionic sector is minimally extended with three right-handed neutrinos, and a successful type-I seesaw mechanism is realized. Charged lepton flavor violation is effectively suppressed, and proton decay—a common prediction of leptoquarks—is postponed to the dimension-6 effective Lagrangian. Unavoidable radiative corrections in the Higgs mass and muon Yukawa favor leptoquark masses interesting for collider searches. The parameters of the model are radiatively stable and can be evolved by the renormalization group to the Planck scale without inconsistencies. Alternative lepton-flavored gauge extensions of the SM, under which leptoquarks become muoquarks, are proposed for comparison.
Learning multivariate new physics D’Agnolo, Raffaele Tito; Grosso, Gaia; Pierini, Maurizio ...
European physical journal. C, Particles and fields,
01/2021, Volume:
81, Issue:
1
Journal Article
Peer reviewed
Open access
We discuss a method that employs a multilayer perceptron to detect deviations from a reference model in large multivariate datasets. Our data analysis strategy does not rely on any prior assumption ...on the nature of the deviation. It is designed to be sensitive to small discrepancies that arise in datasets dominated by the reference model. The main conceptual building blocks were introduced in D’Agnolo and Wulzer (Phys Rev D 99 (1), 015014.
https://doi.org/10.1103/PhysRevD.99.015014
.
arXiv:1806.02350
hep-ph, 2019). Here we make decisive progress in the algorithm implementation and we demonstrate its applicability to problems in high energy physics. We show that the method is sensitive to putative new physics signals in di-muon final states at the LHC. We also compare our performances on toy problems with the ones of alternative methods proposed in the literature.
We review the physics basis, main features and use of general-purpose Monte Carlo event generators for the simulation of proton–proton collisions at the Large Hadron Collider. Topics included are: ...the generation of hard scattering matrix elements for processes of interest, at both leading and next-to-leading QCD perturbative order; their matching to approximate treatments of higher orders based on the showering approximation; the parton and dipole shower formulations; parton distribution functions for event generators; non-perturbative aspects such as soft QCD collisions, the underlying event and diffractive processes; the string and cluster models for hadron formation; the treatment of hadron and tau decays; the inclusion of QED radiation and beyond Standard Model processes. We describe the principal features of the
Ariadne, Herwig++,
Pythia 8 and
Sherpa generators, together with the Rivet and Professor validation and tuning tools, and discuss the physics philosophy behind the proper use of these generators and tools. This review is aimed at phenomenologists wishing to understand better how parton-level predictions are translated into hadron-level events as well as experimentalists seeking a deeper insight into the tools available for signal and background simulation at the LHC.
Abstract We discuss how to calculate cross sections as well as rapidity, transverse momentum and energy distributions of ν τ and ν ¯ τ $$ {\overline{\nu}}_{\tau } $$ produced from the direct D s ± → ...ν τ / ν ¯ τ $$ {D}_s^{\pm}\to {\nu}_{\tau }/{\overline{\nu}}_{\tau } $$ and chain D s ± → τ + / τ − → ν τ / ν ¯ τ $$ {D}_s^{\pm}\to {\tau}^{+}/{\tau}^{-}\to {\nu}_{\tau }/{\overline{\nu}}_{\tau } $$ decays in p+96 Mo scattering with proton beam E lab = 400 GeV i.e. at s NN $$ {\sqrt{s}}_{NN} $$ = 27.4 GeV. The τ decays are simulated with the help of the Tauola code and include multiple decay channels of τ in amounts proportional to their branching ratios. In our calculations we include D s ± $$ {D}_s^{\pm } $$ from charm fragmentation c → D s + $$ {D}_s^{+} $$ and c ¯ → D s − $$ \overline{c}\to {D}_s^{-} $$ as well as those from subleading fragmentation of strange quarks/antiquarks s → D s − $$ {D}_s^{-} $$ and s ¯ → D s + $$ \overline{s}\to {D}_s^{+} $$ . The s ≠ s ¯ $$ s\ne \overline{s} $$ asymmetry of the strange quark content of proton is included. The different contributions to D s + $$ {D}_s^{+} $$ and ν τ / ν ¯ τ $$ {\nu}_{\tau }/{\overline{\nu}}_{\tau } $$ are shown explicitly. We discuss and quantify a not discussed so far effect of asymmetries for production of ν τ and ν ¯ τ $$ {\overline{\nu}}_{\tau } $$ caused by subleading fragmentation mechanism and discuss related uncertainties. A potential measurement of the asymmetry is discussed. Estimates of a number of observed ν τ / ν ¯ τ $$ {\nu}_{\tau }/{\overline{\nu}}_{\tau } $$ in the ν τ / ν ¯ τ $$ {\nu}_{\tau }/{\overline{\nu}}_{\tau } $$ +208Pb reaction, with 2m long target are given with the help of the NuWro program. We refer also to the production of the high-energy (anti)neutrinos in the atmosphere.
An attempt to compare the epistemological positions of two thinkers coming from different philosophical traditions requires turning to the sources of both philosophical programs. This will allow us ...to reveal the common and differentiating features of the described projects. On the one hand, we have Cassirer, the heir to neo-Kantianism and the creator of symbolism, on the other, we are rooted in the tradition of reflective philosophy and phenomenological hermeneutics, Ricoeur. Despite many differences in epistemological assumptions, we can find similar positions in both philosophers. The concurrence of the three Cassirerow base phenomena with three hermeneutic horizons manifests itself - as we will try to demonstrate - in the concept of the Work. The hermeneutic intuition of Cassirer turns into Ricoeur's reflection on self-understanding in the face of a work that affects our perception of the world and thinking about ourselves. In the article, we will consider how the contemporary philosophy of culture developed by Cassirer is taken up by contemporary hermeneutics. Is the convergence of the three base phenomena with the three horizons that combine with each other in the process of interpretation in the juxtaposition of the philosophy of culture with contemporary hermeneutics? Do we have the right to compare Cassirerow's base phenomena, I - You - Work is with hermeneutic communication which is presented on the line Author (Creator) -Text (Work) - Reader (Receiver)?
Motivated by a simultaneous explanation of the apparent discrepancies in the light charged lepton anomalous magnetic dipole moments, and the anomalous internal pair creation in $^{8}$Be nuclear ...transitions, we explore a simple New Physics model, based on an extension of the Standard Model gauge group by a U(1)$_{B−L}$. The model further includes heavy vector-like fermion fields, as well as an extra scalar responsible for the low-scale breaking of U(1)$_{B−L}$, which gives rise to a light Z′ boson. The new fields and currents allow to explain the anomalous internal pair creation in $^{8}$Be while being consistent with various experimental constraints. Interestingly, we find that the contributions of the Z′ and the new U(1)$_{B−L}$-breaking scalar can also successfully account for both (g −2)$_{e,μ}$ anomalies; the strong phenomenological constraints on the model’s parameter space ultimately render the combined explanation of (g − 2)$_{e}$ and the anomalous internal pair creation in $^{8}$Be particularly predictive. The underlying idea of this minimal “prototype model” can be readily incorporated into other protophobic U(1) extensions of the Standard Model.
Scenarios for multi-component scalar dark matter based on a single Z$_{N}$ (N ≥ 4) symmetry are simple and well-motivated. In this paper we investigate, for the first time, the phenomenology of the ...Z$_{5}$ model for two-component dark matter. This model, which can be seen as an extension of the well-known singlet scalar model, features two complex scalar fields — the dark matter particles — that are Standard Model singlets but have different charges under a Z$_{5}$ symmetry. The interactions allowed by the Z$_{5}$ give rise to novel processes between the dark matter particles that affect their relic densities and their detection prospects, which we study in detail. The key parameters of the model are identified and its viable regions are characterized by means of random scans. We show that, unlike the singlet scalar model, dark matter masses below the TeV are still compatible with present data. Even though the dark matter density turns out to be dominated by the lighter component, we find that current and future direct detection experiments may be sensitive to signals from both dark matter particles.
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