scholarly journals The rare and forbidden: Testing physics beyond the standard model with Mu3e

2019 ◽  
Author(s):  
Ann-Kathrin Perrevoort
Keyword(s):  
Standard Model ◽  
Muon Beam ◽  
Effective Field ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
Pixel Sensors ◽  
The Standard Model ◽  
Detailed Simulation ◽  
Momentum Acceptance ◽  
Lepton Flavour

The upcoming Mu3e experiment aims to search for the lepton flavour violating decay \boldsymbol{\muposeeemath} with an unprecedented final sensitivity of one signal decay in \boldsymbol{\num{e16}} observed muon decays by making use of an innovative experimental design based on novel ultra-thin silicon pixel sensors. In a first phase, the experiment is operated at an existing muon beam line with rates of up to \boldsymbol{\num{e8}} muons per second. Detailed simulation studies confirm the feasibility of background-free operation and project single event sensitivities in the order of \boldsymbol{\num{e-15}} for signal decays modelled in an effective field theory approach. The precise tracking of the decay electrons and large geometric and momentum acceptance of Mu3e enable searches for physics beyond the Standard Model in further signatures. Examples of which are searches for lepton flavour violating two-body decays of the muon into an electron and an undetected boson as well as for electron-positron resonances in \boldsymbol{\muposeeenunumath} which could result for instance from a dark photon decay. The Mu3e experiment is expected to be competitive in all of these channels already in phase I.

scholarly journals Effective Theory Approach to Direct Detection of Dark Matter

2020 ◽  
pp. 650-688
Author(s):  
Junji Hisano
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Particle Physics ◽  
Direct Detection ◽  
Effective Field ◽  
Weakly Interacting Massive Particles ◽  
Effective Theory ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
The Standard Model

It is now certain that dark matter exists in the Universe. However, we do not know its nature, nor are there dark matter candidates in the standard model of particle physics or astronomy However, weakly interacting massive particles (WIMPs) in models beyond the standard model are one of the leading candidates available to provide explanation. The dark matter direct detection experiments, in which the nuclei recoiled by WIMPs are sought, are one of the methods to elucidate the nature of dark matter. This chapter introduces an effective field theory (EFT) approach in order to evaluate the nucleon–WIMP elastic scattering cross section.

scholarly journals Tests of Lepton Flavour Universality at LHCb

2018 ◽  
Vol 46 ◽  
pp. 1860070
Author(s):  
Anna Lupato
Keyword(s):  
Standard Model ◽  
Beyond The Standard Model ◽  
Centre Of Mass ◽  
Gauge Bosons ◽  
B Quarks ◽  
Clear Sign ◽  
The Standard Model ◽  
8 Tev ◽  
Using Data ◽  
Lepton Flavour

In the Standard Model the electroweak coupling of the gauge bosons to leptons is independent of the lepton flavour. Semileptonic and rare decays of b quarks provide an ideal laboratory to test this property. Any violation of Lepton Flavour Universality would be a clear sign of physics beyond the Standard Model. In this work a review of the Lepton Flavour Universality tests performed using data collected by the LHCb experiment in 2011 and 2012 at a centre of mass energy of 7 and 8 TeV is presented.

scholarly journals Mapping Effective Field Theory to Multifractal Geometry

2021 ◽  
Author(s):  
Ervin Goldfain
Keyword(s):  
Field Theory ◽  
Nonlinear Dynamics ◽  
Partition Function ◽  
Standard Model ◽  
Effective Field Theory ◽  
Effective Field ◽  
Beyond The Standard Model ◽  
Euclidean Metric ◽  
Classical Chaos ◽  
The Standard Model

Fractals and multifractals are well-known trademarks of nonlinear dynamics and classical chaos. The goal of this work is to tentatively uncover the unforeseen path from multifractals and selfsimilarity to the framework of effective field theory (EFT). An intriguing finding is that the partition function of multifractal geometry includes the signature of non-Euclidean metric. Our results also suggest that multifractal geometry may offer insights into the non-renormalizable interactions presumed to develop beyond the Standard Model scale.

scholarly journals Lepton-flavour non-universality of $${\bar{B}}\rightarrow D^*\ell {{\bar{\nu }}}$$ angular distributions in and beyond the Standard Model

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Christoph Bobeth ◽  
Marzia Bordone ◽  
Nico Gubernari ◽  
Martin Jung ◽  
Danny van Dyk
Keyword(s):  
Experimental Data ◽  
Standard Model ◽  
Effective Theory ◽  
Angular Distributions ◽  
Beyond The Standard Model ◽  
Mass Effects ◽  
Muon Mass ◽  
The Standard Model ◽  
Current Experimental Data ◽  
Lepton Flavour

AbstractWe analyze in detail the angular distributions in $${\bar{B}}\rightarrow D^*\ell {{\bar{\nu }}}$$ B ¯ → D ∗ ℓ ν ¯ decays, with a focus on lepton-flavour non-universality. We investigate the minimal number of angular observables that fully describes current and upcoming datasets, and explore their sensitivity to physics beyond the Standard Model (BSM) in the most general weak effective theory. We apply our findings to the current datasets, extract the non-redundant set of angular observables from the data, and compare to precise SM predictions that include lepton-flavour universality violating mass effects. Our analysis shows that the number of independent angular observables that can be inferred from current experimental data is limited to only four. These are insufficient to extract the full set of relevant BSM parameters. We uncover a $$\sim 4\sigma $$ ∼ 4 σ tension between data and predictions that is hidden in the redundant presentation of the Belle 2018 data on $${\bar{B}}\rightarrow D^*\ell {{\bar{\nu }}}$$ B ¯ → D ∗ ℓ ν ¯ decays. This tension specifically involves observables that probe $$e-\mu $$ e - μ lepton-flavour universality. However, we find inconsistencies in these data, which renders results based on it suspicious. Nevertheless, we discuss which generic BSM scenarios could explain the tension, in the case that the inconsistencies do not affect the data materially. Our findings highlight that $$e-\mu $$ e - μ non-universality in the SM, introduced by the finite muon mass, is already significant in a subset of angular observables with respect to the experimental precision.

scholarly journals Exclusion Limits on a Scalar Decaying to Photons and Distinguishing Its Production Mechanisms

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Tanumoy Mandal
Keyword(s):  
Cross Sections ◽  
Effective Field Theory ◽  
Gluon Fusion ◽  
Effective Field ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
The Standard Model ◽  
Resonance Search ◽  
Model Independent ◽  
Production Mechanisms

LHC run-II has a great potential to search for new resonances in the diphoton channel. Latest 13 TeV data already put stringent limits on the cross sections in the diphoton channel assuming the resonance is produced through the gluon-gluon fusion. Many beyond the Standard Model (SM) theories predict TeV-scale scalars, which copiously decay to diphotons. Apart from the gluon-gluon fusion production, these scalars can also be dominantly produced in other ways too at the LHC, namely, through the quark-quark fusion or the gauge boson fusions like the photon-photon, photon-Z, WW, or ZZ fusions. In this paper we use an effective field theory approach where a heavy scalar can be produced in various ways and recast the latest ATLAS diphoton resonance search to put model-independent limits on its mass and effective couplings to the SM particles. If a new scalar is discovered at the LHC, it would be very important to identify its production mechanism in order to probe the nature of the underlying theory. We show that combining various kinematic variables in a multivariate analysis can be very powerful to distinguish different production mechanisms from one another.

scholarly journals Non-perturbative renormalization scheme for the C P -odd three-gluon operator

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Vincenzo Cirigliano ◽  
Emanuele Mereghetti ◽  
Peter Stoffer
Keyword(s):  
Standard Model ◽  
Lattice Qcd ◽  
Electric Dipole ◽  
Dipole Moments ◽  
Effective Field ◽  
Renormalization Scheme ◽  
Beyond The Standard Model ◽  
Matrix Elements ◽  
The Standard Model ◽  
Perturbative Renormalization

Abstract We define a regularization-independent momentum-subtraction scheme for the C P -odd three-gluon operator at dimension six. This operator appears in effective field theories for heavy physics beyond the Standard Model, describing the indirect effect of new sources of C P-violation at low energies. In a hadronic context, it induces permanent electric dipole moments. The hadronic matrix elements of the three-gluon operator are non-perturbative objects that should ideally be evaluated with lattice QCD. We define a non-perturbative renormalization scheme that can be implemented on the lattice and we compute the scheme transformation to $$ \overline{\mathrm{MS}} $$ MS ¯ at one loop. Our calculation can be used as an interface to future lattice-QCD calculations of the matrix elements of the three-gluon operator, in order to obtain theoretically robust constraints on physics beyond the Standard Model from measurements of the neutron electric dipole moment.

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