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Register a new userSMEFTsim 3.0 -- a practical guide
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Ilaria Brivio
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The SMEFTsim package is designed to enable automated computations in the Standard Model Effective Field Theory (SMEFT), where the SM Lagrangian is extended with a complete basis of dimension six operators. It contains a set of models written in FeynRules and pre-exported to the UFO format, for usage within Monte Carlo event generators. The models differ in the flavor assumptions and in the input parameters chosen for the electroweak sector. The present document provides a self-contained, pedagogical reference that collects all the theoretical and technical aspects relevant to the use of SMEFTsim and it documents the release of version 3.0. Compared to the previous release, the description of Higgs production via gluon-fusion in the SM has been significantly improved, two flavor assumptions for studies in the top quark sector have been added, and a new feature has been implemented, that allows the treatment of linearized SMEFT corrections to the propagators of unstable particles.
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A method to determine masses, widths and coupling constants of vector mesons, like phi(1020), omega(782) and rho0(770) recurrences is defined. Starting from data on decay rates and cross sections for the processes: phi -> M_I gamma, phi -> M_I e+e- and e+e- -> M_I phi, where M_I is a pseudoscalar or scalar meson with isospin I=0,1, the time-like transition form factors, which describe the vertex phi-gamma-M_I, are parametrized using a vector meson-propagators description in the low energy region <3-4 GeV, the quark-counting rule prescription for the high energy behavior, and the analyticity imposed by means of the dispersion relations.
Malliavin weight sampling (MWS) is a stochastic calculus technique for computing the derivatives of averaged system properties with respect to parameters in stochastic simulations, without perturbing the systems dynamics. It applies to systems in or out of equilibrium, in steady state or time-dependent situations, and has applications in the calculation of response coefficients, parameter sensitivities and Jacobian matrices for gradient-based parameter optimisation algorithms. The implementation of MWS has been described in the specific contexts of kinetic Monte Carlo and Brownian dynamics simulation algorithms. Here, we present a general theoretical framework for deriving the appropriate MWS update rule for any stochastic simulation algorithm. We also provide pedagogical information on its practical implementation.
The masses of excited charmed mesons are shown to decrease by $sim (50-150)$~MeV due to a flattening of the confining potential at large distances, which effectively takes into account open decay channels. The scale of the mass shifts is similar to that in charmonium for $psi(4660)$ and $chi_{c0}(4700)$. The following masses of the first excitations: $M(2,{}^3P_0)=2874$~MeV, $M(2,{}^3P_2)=2968$~MeV, $M(2,{}^3D_1)=3175$~MeV, and $M(2,{}^3D_3)=3187$~MeV, and second excitations: $M(3,{}^1S_0)=3008$~MeV, $M(3,{}^3S_1)=3062$~MeV, $M(3,{}^3P_0)=3229$~MeV, and $M(3,{}^3P_2) =3264$~MeV, are predicted. The other states with $L=0,1,2$ and $n_r geq 3$ have their masses in the region $M(nL)geq 3.3$~GeV.
We lay out a comprehensive physics case for a future high-energy muon collider, exploring a range of collision energies (from 1 to 100 TeV) and luminosities. We highlight the advantages of such a collider over proposed alternatives. We show how one can leverage both the point-like nature of the muons themselves as well as the cloud of electroweak radiation that surrounds the beam to blur the dichotomy between energy and precision in the search for new physics. The physics case is buttressed by a range of studies with applications to electroweak symmetry breaking, dark matter, and the naturalness of the weak scale. Furthermore, we make sharp connections with complementary experiments that are probing new physics effects using electric dipole moments, flavor violation, and gravitational waves. An extensive appendix provides cross section predictions as a function of the center-of-mass energy for many canonical simplified models.
Multi-image alignment, bringing a group of images into common register, is an ubiquitous problem and the first step of many applications in a wide variety of domains. As a result, a great amount of effort is being invested in developing efficient multi-image alignment algorithms. Little has been done, however, to answer fundamental practical questions such as: what is the comparative performance of existing methods? is there still room for improvement? under which conditions should one technique be preferred over another? does adding more images or prior image information improve the registration results? In this work, we present a thorough analysis and evaluation of the main multi-image alignment methods which, combined with theoretical limits in multi-image alignment performance, allows us to organize them under a common framework and provide practical answers to these essential questions.
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