Regularization in low-energy standard model calculations

1990 ◽  
Vol 237 (2) ◽  
pp. 252-255 ◽  
Author(s):  
Robert Grigjanis ◽  
Patrick J. O'Donnell ◽  
Mark Sutherland ◽  
Henri Navelet
Keyword(s):  
Standard Model ◽  
Low Energy ◽  
Model Calculations

scholarly journals Flavour Anomalies in a U(1) SUSY Extension of the SM

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 191
Author(s):  
Alexander Bednyakov ◽  
Alfiia Mukhaeva
Keyword(s):  
Standard Model ◽  
Parameter Space ◽  
Gauge Boson ◽  
New Physics ◽  
Low Energy ◽  
Effective Theory ◽  
The Standard Model ◽  
Meson Mixing ◽  
Additional Anomaly ◽  
Lepton Flavour

Flavour anomalies have attracted a lot of attention over recent years as they provide unique hints for possible New Physics. Here, we consider a supersymmetric (SUSY) extension of the Standard Model (SM) with an additional anomaly-free gauge U(1) group. The key feature of our model is the particular choice of non-universal charges to the gauge boson Z′, which not only allows a relaxation of the flavour discrepancies but, contrary to previous studies, can reproduce the SM mixing matrices both in the quark and lepton sectors. We pay special attention to the latter and explicitly enumerate all parameters relevant for our calculation in the low-energy effective theory. We find regions in the parameter space that satisfy experimental constraints on meson mixing and LHC Z′ searches and can alleviate the flavour anomalies. In addition, we also discuss the predictions for lepton-flavour violating decays B+→K+μτ and B+→K+eτ.

scholarly journals A FOUR-DIMENSIONAL SUPERSTRING FROM THE BOSONIC STRING WITH SOME APPLICATIONS

2005 ◽  
Vol 20 (01) ◽  
pp. 99-128 ◽  
Author(s):  
B. B. DEO ◽  
L. MAHARANA
Keyword(s):  
Standard Model ◽  
Central Charge ◽  
Virasoro Algebra ◽  
Low Energy ◽  
Majorana Fermions ◽  
Modular Invariance ◽  
Model Group ◽  
Supersymmetry Algebra ◽  
Four Dimensions ◽  
Bosonic Representation

A string in four dimensions is constructed by supplementing it with 44 Majorana fermions. The later are represented by 11 vectors in the bosonic representation SO (D-1,1). The central charge is 26. The fermions are grouped in such a way that the resulting action is worldsheet supersymmetric. The energy–momentum and current generators satisfy the super-Virasoro algebra. GSO projections are necessary for proving modular invariance. Space–time supersymmetry algebra is deduced and is substantiated for specific modes of zero mass. The symmetry group of the model can descend to the low energy standard model group SU (3)× SU L(2)× U Y(1) through the Pati–Salam group.

scholarly journals Renormalization group consistency and low-energy effective theories

2019 ◽  
Vol 6 (5) ◽  
Author(s):  
Jens Braun ◽  
Marc Leonhardt ◽  
Jan M. Pawlowski
Keyword(s):  
Renormalization Group ◽  
Mean Field ◽  
Bound State ◽  
Field Approximation ◽  
Low Energy ◽  
Mean Field Approximation ◽  
Quantum Field Theories ◽  
Model Calculations ◽  
Effective Models ◽  
Effective Theories

Low-energy effective theories have been used very successfully to study the low-energy limit of QCD, providing us with results for a plethora of phenomena, ranging from bound-state formation to phase transitions in QCD. These theories are consistent quantum field theories by themselves and can be embedded in QCD, but typically have a physical ultraviolet cutoff that restricts their range of validity. Here, we provide a discussion of the concept of renormalization group consistency, aiming at an analysis of cutoff effects and regularization-scheme dependences in general studies of low-energy effective theories. For illustration, our findings are applied to low-energy effective models of QCD in different approximations including the mean-field approximation. More specifically, we consider hot and dense as well as finite systems and demonstrate that violations of renormalization group consistency affect significantly the predictive power of the corresponding model calculations.

scholarly journals p-Wave Strength in the Low-energy 7Li(p,?0)8Be Cross Section

1995 ◽  
Vol 48 (5) ◽  
pp. 813 ◽  
Author(s):  
FC Barker
Keyword(s):  
Angular Distribution ◽  
Shell Model ◽  
Cross Section ◽  
Low Energy ◽  
P Wave ◽  
Model Calculations ◽  
Energy Data

Recent fits to low-energy 7Li(p, "Yo)8Be angular distribution and analysing power data suggested a large p-wave strength. It is shown that acceptable fits to the data can be obtained by attributing the p-wave Ml contributions to the tails of the 17 �64 and 18 �15 MeV 1+ levels of 8Be, with p-wave strengths much less than those obtained previously, but only if some of the spectroscopic amplitudes have signs opposite to those suggested by shell model calculations and/or a fit to higher-energy data.

scholarly journals Rb, Rc and New Physics: An Updated Model Independent Analysis

1997 ◽  
Vol 12 (04) ◽  
pp. 723-742 ◽  
Author(s):  
P. Bamert
Keyword(s):  
Standard Model ◽  
Neutral Current ◽  
New Physics ◽  
Low Energy ◽  
Coupling Constant ◽  
A Value ◽  
Independent Analysis ◽  
The Standard Model ◽  
Necessary And Sufficient ◽  
Do So

We analyze LEP and SLC data from the 1995 Summer Conferences as well as from low energy neutral current experiments for signals of new physics. The reasons for doing this are twofold: first to explain the deviations from the Standard Model observed in Rb and Rc and second to constrain nonstandard contributions to couplings of the Z0 boson to all fermions and to the oblique parameters. We do so by comparing the data with the Standard Model as well as with a number of test hypotheses concerning the nature of the new physics. These include nonstandard [Formula: see text]-, [Formula: see text]- and [Formula: see text]-couplings as well as the couplings of the Z0 to fermions of the entire first, second and third generations and universal corrections to all up- and down-type quark couplings (as can arise see for example in Z' mixing models). We find that nonstandard [Formula: see text] couplings are both necessary and sufficient to explain the data and in particular the Rb anomaly. It is not possible to explain Rb, Rc and a value of the strong coupling constant consistent with low energy determinations invoking only nonstandard [Formula: see text]- and [Formula: see text]-couplings. To do so one has to have also new physics contributions to the [Formula: see text] or universal corrections to all [Formula: see text] couplings.

TECHNIDILATON OR HIGGS?

1993 ◽  
Vol 08 (03) ◽  
pp. 275-283 ◽  
Author(s):  
EDI HALYO
Keyword(s):  
Standard Model ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Higgs Bosons ◽  
Low Energy ◽  
Gauge Bosons ◽  
Effective Lagrangian ◽  
The Standard Model

Interactions of the technidilaton with fermions and gauge bosons are obtained by constructing a low energy effective Lagrangian and using the fact that the technidilaton couples to the trace of the energy-momentum tensor Θµµ. Technidilaton’s interactions are compared with those of the Higgs bosons of the Standard Model with one or two scalar doublets.

scholarly journals Analyses of Wolf-Rayet Spectra

1991 ◽  
Vol 143 ◽  
pp. 81-86
Author(s):  
W.-R. Hamann
Keyword(s):  
Quantitative Analysis ◽  
Standard Model ◽  
Emission Line ◽  
Massive Stars ◽  
Stellar Atmospheres ◽  
Model Calculations ◽  
Plane Parallel ◽  
Long Time ◽  
Effective Temperatures ◽  
Static Plane

Wolf-Rayet stars represent an important stage in the evolution of massive stars, but are only poorly understood so far. For a better knowledge one might determine their effective temperatures, luminosities and atmospheric compositions. But the emission-line dominated Wolf-Rayet spectra were not accessible to a quantitative analysis for a long time, because “standard” model calculations for static, plane-parallel stellar atmospheres are not adequate to that type of stars.

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