scholarly journals Measurement of the transverse polarization of electrons emitted in neutron decay – nTRV experiment

2021 ◽  
Author(s):  
Kazimierz Bodek ◽  
Adam Kozela
Keyword(s):  
Standard Model ◽  
Time Reversal ◽  
Correlation Coefficients ◽  
Relative Strength ◽  
Transverse Polarization ◽  
Scalar Coupling ◽  
Beyond The Standard Model ◽  
Coupling Constant ◽  
Scalar Coupling Constant ◽  
The Standard Model

This paper recalls the main achievements of the nTRV experiment which measured two components of the transverse polarization (\sigma_{T_{1}}σT1, \sigma_{T_{2}}σT2) of electrons emitted in the \betaβ-decay of polarized, free neutrons and deduced two correlation coefficients, RR and NN, that are sensitive to physics beyond the Standard Model. The value of time-reversal odd coefficient RR, 0.004\pm±0.012\pm±0.005, significantly improved limits on the relative strength of imaginary scalar coupling constant in the weak interaction. The value obtained for the time-reversal even correlation coefficient NN, 0.067\pm±0.011\pm±0.004, agrees with the Standard Model expectation, providing an important sensitivity test of the electron polarimeter. One of the conclusions of this pioneering experiment was that the transverse electron polarization in the neutron \betaβ-decay is worth more systematic exploring by measurements of yet experimentally not attempted correlation coefficients such as HH, LL, SS, UU and VV. This article presents a brief outlook on that questions.

CAN WE RELATE TIME-REVERSAL VIOLATION TO NEW PHYSICS PROCESSES IN WEAK HADRONIC DECAYS?

2013 ◽  
Vol 22 (03) ◽  
pp. 1330006 ◽  
Author(s):  
Z. J. AJALTOUNI ◽  
E. DI SALVO
Keyword(s):  
Experimental Data ◽  
Cp Violation ◽  
Standard Model ◽  
Time Reversal ◽  
Review Paper ◽  
New Physics ◽  
Hadronic Decays ◽  
Beyond The Standard Model ◽  
Weak Decays ◽  
The Standard Model

This review paper stresses the possible connection between time-reversal violation and new physics processes beyond the standard model. In particular, this violation is proposed as an alternative to CP violation in the search for such unkown processes. Emphasis is put on the weak decays of heavy hadrons, especially beauty ones. Specific methods for extracting useful parameters from experimental data are elaborated in order to test TR symmetry. These methods could be used successfully in the analysis of the LHC data.

scholarly journals Sub-GeV-scale signatures of hidden braneworlds up to the Planck scale in a SO(3,1)-broken bulk

2019 ◽  
Vol 34 (05) ◽  
pp. 1950029 ◽  
Author(s):  
Coraline Stasser ◽  
Michaël Sarrazin
Keyword(s):  
Standard Model ◽  
Phenomenological Model ◽  
Quantum Dynamics ◽  
Scale Up ◽  
Planck Scale ◽  
Energy Scale ◽  
Beyond The Standard Model ◽  
Coupling Constant ◽  
The Standard Model ◽  
Gut Scale

Many-brane Universes are at the heart of several cosmological scenarios related to physics beyond the Standard Model. It is then a major concern to constrain these approaches. Two-brane Universes involving [Formula: see text]-broken 5D bulks are among the cosmological models of interest. They also allow considering matter exchange between branes, a possible way to test these scenarios. Neutron disappearance (reappearance) toward (from) the hidden brane is currently tested with high-precision experiments to constrain the coupling constant [Formula: see text] between the visible and hidden neutron sectors. When dealing with the sub-GeV-scale quantum dynamics of fermions, any pair of braneworlds can be described by a noncommutative two-sheeted space–time [Formula: see text] from which [Formula: see text] emerges. Nevertheless, the calculation of the formal link between [Formula: see text] for a neutron and [Formula: see text]-broken 5D bulks remains an open problem until now although necessary to constrain these braneworld scenarios. Thanks to a phenomenological model, we derive [Formula: see text] — for a neutron — between the two braneworlds endowed with their own copy of the Standard Model in an [Formula: see text]-broken 5D bulk. Constraints on interbrane distance and brane energy scale (or brane thickness) are discussed. While brane energy scale below the GUT scale is excluded, energy scale up to the Planck limit allows neutron swapping detection in forthcoming experiments.

scholarly journals Searching for new physics in semi-leptonic baryon decays

2017 ◽  
Vol 32 (08) ◽  
pp. 1750043 ◽  
Author(s):  
E. Di Salvo ◽  
Z. J. Ajaltouni
Keyword(s):  
Standard Model ◽  
Decay Width ◽  
Form Factors ◽  
New Physics ◽  
Scalar Coupling ◽  
Partial Decay Width ◽  
Beyond The Standard Model ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Pseudo Scalar

We propose two different and complementary observables for singling out possible signals of physics beyond the Standard Model (SM) in the semi-leptonic decays [Formula: see text], both with the [Formula: see text] lepton and with a light lepton. The two observables are the partial decay width and a T-odd asymmetry, whose respective sensitivities to scalar and/or pseudo-scalar coupling are calculated as functions of the parameters characterizing new physics (NP). Two different form factors are used. Three particular cases are discussed and analyzed in detail.

scholarly journals INTERFERENCE EFFECTS, TIME REVERSAL VIOLATION AND SEARCH FOR NEW PHYSICS IN HADRONIC WEAK DECAYS

2012 ◽  
Vol 27 (16) ◽  
pp. 1250086 ◽  
Author(s):  
Z. J. AJALTOUNI ◽  
E. DI SALVO
Keyword(s):  
Standard Model ◽  
Decay Width ◽  
Time Reversal ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Interference Effects ◽  
Decay Channels ◽  
Weak Decays ◽  
The Standard Model ◽  
Almost All

We propose some methods for studying hadronic sequential two-body decays involving more spinning particles. It relies on the analysis of T-odd and T-even asymmetries, which are related to interference terms. The latter asymmetries turn out to be as useful as the former ones in inferring time reversal violating observables; these in turn may be sensitive, under some particular conditions, to possible contributions beyond the standard model. Our main result is that one can extract such observables even after integrating the differential decay width over almost all of the available angles. Moreover we find that the correlations based exclusively on momenta are quite general, since they provide as much information as those involving one or more spins. We generalize some methods already proposed in the literature for particular decay channels, but we also pick out a new kind of time reversal violating observables. Our analysis could be applied, for example, to data of LHCb experiment.

Beyond the Standard Model

2017 ◽  
Author(s):  
Laurent Baulieu ◽  
John Iliopoulos ◽  
Roland Sénéor
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Supergravity Models ◽  
Standard Model ◽  
Field Theories ◽  
Beyond The Standard Model ◽  
Super Symmetry ◽  
The Standard Model ◽  
Topological Field ◽  
Supersymmetric Theories

The motivation for supersymmetry. The algebra, the superspace, and the representations. Field theory models and the non-renormalisation theorems. Spontaneous and explicit breaking of super-symmetry. The generalisation of the Montonen–Olive duality conjecture in supersymmetric theories. The remarkable properties of extended supersymmetric theories. A brief discussion of twisted supersymmetry in connection with topological field theories. Attempts to build a supersymmetric extention of the standard model and its experimental consequences. The property of gauge supersymmetry to include general relativity and the supergravity models.

scholarly journals Search for dark matter in association with an energetic photon in pp collisions at $$ \sqrt{s} $$ = 13 TeV with the ATLAS detector

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Dark Matter ◽  
Transverse Momentum ◽  
Standard Model ◽  
Confidence Level ◽  
Axial Vector ◽  
Beyond The Standard Model ◽  
Proton Proton ◽  
Missing Transverse Momentum ◽  
Upper Limits ◽  
The Standard Model

Abstract A search for dark matter is conducted in final states containing a photon and missing transverse momentum in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV. The data, collected during 2015–2018 by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 fb−1. No deviations from the predictions of the Standard Model are observed and 95% confidence-level upper limits between 2.45 fb and 0.5 fb are set on the visible cross section for contributions from physics beyond the Standard Model, in different ranges of the missing transverse momentum. The results are interpreted as 95% confidence-level limits in models where weakly interacting dark-matter candidates are pair-produced via an s-channel axial-vector or vector mediator. Dark-matter candidates with masses up to 415 (580) GeV are excluded for axial-vector (vector) mediators, while the maximum excluded mass of the mediator is 1460 (1470) GeV. In addition, the results are expressed in terms of 95% confidence-level limits on the parameters of a model with an axion-like particle produced in association with a photon, and are used to constrain the coupling gaZγ of an axion-like particle to the electroweak gauge bosons.

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