scholarly journals NNLO virtual and real leptonic corrections to muon-electron scattering

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Ettore Budassi ◽  
Carlo M. Carloni Calame ◽  
Mauro Chiesa ◽  
Clara Lavinia Del Pio ◽  
Syed Mehedi Hasan ◽  
...  
Keyword(s):  
Electron Scattering ◽  
Monte Carlo Code ◽  
Radiative Corrections ◽  
Leading Order ◽  
Muon Anomalous Magnetic Moment ◽  
Small Momentum Transfer ◽  
Hadronic Contribution ◽  
Typical Event ◽  
Fixed Order

Abstract The recently proposed MUonE experiment at CERN aims at providing a novel determination of the leading order hadronic contribution to the muon anomalous magnetic moment through the study of elastic muon-electron scattering at relatively small momentum transfer. The anticipated accuracy of the order of 10ppm demands for high-precision predictions, including all the relevant radiative corrections. The fixed-order NNLO radiative corrections due to the emission of virtual and real leptonic pairs are described and their numerical impact is discussed for typical event selections of the MUonE experiment, by means of the upgraded Monte Carlo code Mesmer.

scholarly journals Towards muon-electron scattering at NNLO

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Carlo M. Carloni Calame ◽  
Mauro Chiesa ◽  
Syed Mehedi Hasan ◽  
Guido Montagna ◽  
Oreste Nicrosini ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Electron Scattering ◽  
Photon Radiation ◽  
Monte Carlo Code ◽  
Radiative Corrections ◽  
Small Momentum Transfer ◽  
Simulation Code ◽  
Theoretical Formulation ◽  
Loop Contribution ◽  
The Impact

Abstract The recently proposed MUonE experiment at CERN aims at providing a novel determination of the leading order hadronic contribution to the muon anomalous magnetic moment through the study of elastic muon-electron scattering at relatively small momentum transfer. The anticipated accuracy of the order of 10ppm demands for high-precision predictions, including all the relevant radiative corrections. The theoretical formulation for the fixed-order NNLO photonic radiative corrections is described and the impact of the numerical results obtained with the corresponding Monte Carlo code is discussed for typical event selections of the MUonE experiment. In particular, the gauge-invariant subsets of corrections due to electron radiation as well as to muon radiation are treated exactly. The two-loop contribution due to diagrams where at least two virtual photons connect the electron and muon lines is approximated taking inspiration from the classical Yennie-Frautschi-Suura approach. The calculation and its Monte Carlo implementation pave the way towards the realization of a simulation code incorporating the full set of NNLO corrections matched to multiple photon radiation, that will be ultimately needed for data analysis.

scholarly journals Lattice calculation of the hadronic leading order contribution to the muon g − 2

2020 ◽  
Vol 234 ◽  
pp. 01016
Author(s):  
Hartmut Wittig ◽  
Antoine Gérardin ◽  
Marco Cè ◽  
Georg von Hippel ◽  
Ben Hörz ◽  
...  
Keyword(s):  
Standard Model Prediction ◽  
Detailed Comparison ◽  
New Physics ◽  
Current Status ◽  
Leading Order ◽  
Lattice Calculation ◽  
Muon Anomalous Magnetic Moment ◽  
The Standard Model ◽  
Vacuum Polarisation

The persistent discrepancy of about 3.5 standard deviations between the experimental measurement and the Standard Model prediction for the muon anomalous magnetic moment, aµ, is one of the most promising hints for the possible existence of new physics. Here we report on our lattice QCD calculation of the hadronic vacuum polarisation contribution $ a_\mu ^{{\rm{hvp}}} $, based on gauge ensembles with Nf = 2 + 1 flavours of O(a) improved Wilson quarks. We address the conceptual and numerical challenges that one encounters along the way to a sub-percent determination of the hadronic vacuum polarisation contribution. The current status of lattice calculations of $ a_\mu ^{{\rm{hvp}}} $ is presented by performing a detailed comparison with the results from other groups.

scholarly journals A first determination of parton distributions with theoretical uncertainties

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Rabah Abdul Khalek ◽  
Richard D. Ball ◽  
Stefano Carrazza ◽  
Stefano Forte ◽  
Tommaso Giani ◽  
...  
Keyword(s):  
Covariance Matrix ◽  
Hadron Collider ◽  
Distribution Functions ◽  
Leading Order ◽  
Parton Distribution Functions ◽  
Parton Distributions ◽  
Central Values ◽  
Sources Of Uncertainty ◽  
Fixed Order

Abstract The parton distribution functions (PDFs) which characterize the structure of the proton are currently one of the dominant sources of uncertainty in the predictions for most processes measured at the Large Hadron Collider (LHC). Here we present the first extraction of the proton PDFs that accounts for the missing higher order uncertainty (MHOU) in the fixed-order QCD calculations used in PDF determinations. We demonstrate that the MHOU can be included as a contribution to the covariance matrix used for the PDF fit, and then introduce prescriptions for the computation of this covariance matrix using scale variations. We validate our results at next-to-leading order (NLO) by comparison to the known next order (NNLO) corrections. We then construct variants of the NNPDF3.1 NLO PDF set that include the effect of the MHOU, and assess their impact on the central values and uncertainties of the resulting PDFs.

scholarly journals Muon-electron scattering at next-to-leading order accuracy

2019 ◽  
Vol 212 ◽  
pp. 05002
Author(s):  
Carlo M. Carloni Calame ◽  
Mauro Chiesa ◽  
Guido Montagna ◽  
Oreste Nicrosini ◽  
Fulvio Piccinini
Keyword(s):  
Monte Carlo Event ◽  
Event Generator ◽  
Radiative Corrections ◽  
Leading Order ◽  
Coupling Constant ◽  
High Precision Measurement ◽  
Running Coupling ◽  
Hadronic Correction ◽  
Running Coupling Constant

The next-to-leading order electro-weak radiative corrections to the µ±e- → µ±e- process are reviewed and their relevance is discussed for the MUonE experiment, proposed at CERN. The aim of MUonE is the high precision measurement of the QED running coupling constant in the space-like region, from which the full hadronic contribution can be extracted and used to provide a new and independent determination of the leading-order hadronic correction to the muon g − 2. In this context, the required accuracy demands that radiative corrections are accounted for at the highest level of precision and implemented into a Monte Carlo event generator for data analysis. The first step towards the final goal of theoretical precision, which will require the full set of NNLO corrections and resummation of higher orders, is the inclusion of NLO electro-weak corrections.

Inelastic Electron Scattering from Valence Electrons in Aluminum

1976 ◽  
Vol 34 ◽  
pp. 462-463
Author(s):  
P. E. Batson ◽  
C. H. Chen ◽  
J. Silcox
Keyword(s):  
Electron Scattering ◽  
Single Scattering ◽  
Three Dimensions ◽  
Inelastic Electron ◽  
Weak Beam ◽  
Scattering Spectrum ◽  
Valence Electrons ◽  
Diffraction Patterns ◽  
Electronic Scattering

We wish to report in this paper measurements of the inelastic scattering component due to the collective excitations (plasmons) and single particlehole excitations of the valence electrons in Al. Such scattering contributes to the diffuse electronic scattering seen in electron diffraction patterns and has recently been considered of significance in weak-beam images (see Gai and Howie) . A major problem in the determination of such scattering is the proper correction for multiple scattering. We outline here a procedure which we believe suitably deals with such problems and report the observed single scattering spectrum.In principle, one can use the procedure of Misell and Jones—suitably generalized to three dimensions (qx, qy and #x2206;E)--to derive single scattering profiles. However, such a computation becomes prohibitively large if applied in a brute force fashion since the quasi-elastic scattering (and associated multiple electronic scattering) extends to much larger angles than the multiple electronic scattering on its own.

scholarly journals Constraints on neutrino non-standard interactions from LHC data with large missing transverse momentum

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
DianYu Liu ◽  
ChuanLe Sun ◽  
Jun Gao
Keyword(s):  
Transverse Momentum ◽  
Neutral Current ◽  
Data Sets ◽  
Leading Order ◽  
Missing Transverse Momentum ◽  
Upper Limit ◽  
Theoretical Predictions ◽  
Parton Showering ◽  
Single Jet

Abstract The possible non-standard interactions (NSIs) of neutrinos with matter plays important role in the global determination of neutrino properties. In our study we select various data sets from LHC measurements at 13 TeV with integrated luminosities of 35 ∼ 139 fb−1, including production of a single jet, photon, W/Z boson, or charged lepton accompanied with large missing transverse momentum. We derive constraints on neutral-current NSIs with quarks imposed by different data sets in a framework of either effective operators or simplified Z′ models. We use theoretical predictions of productions induced by NSIs at next-to-leading order in QCD matched with parton showering which stabilize the theory predictions and result in more robust constraints. In a simplified Z′ model we obtain a 95% CLs upper limit on the conventional NSI strength ϵ of 0.042 and 0.0028 for a Z′ mass of 0.2 and 2 TeV respectively. We also discuss possible improvements from future runs of LHC with higher luminosities.

scholarly journals Determination of the strange quark content of the nucleon from a next-to-leading-order QCD analysis of neutrino charm production

1995 ◽  
Vol 65 (2) ◽  
pp. 189-198 ◽  
Author(s):  
◽  
A. O. Bazarko ◽  
C. G. Arroyo ◽  
K. T. Bachmann ◽  
T. Bolton ◽  
...  
Keyword(s):  
Strange Quark ◽  
Charm Production ◽  
Leading Order ◽  
Qcd Analysis ◽  
Quark Content
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