Augmented standard model and the simplest scenario

2015 ◽  
Vol 30 (32) ◽  
pp. 1550201 ◽  
Author(s):  
Tai Tsun Wu ◽  
Sau Lan Wu
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Higgs Doublet ◽  
Atlas Collaboration ◽  
Mass Relation ◽  
New Era ◽  
Left Handed ◽  
Starting Point ◽  
The Right ◽  
The Masses

The experimental discovery of the Higgs particle in 2012 by the ATLAS Collaboration and the CMS Collaboration at CERN ushers in a new era of particle physics. On the basis of these data, scalar quarks and scalar leptons are added to each generation of quarks and leptons. The resulting augmented standard model has fermion–boson symmetry for each of three generations, but only one Higgs doublet giving masses to all the elementary particles. A specific special case, the simplest scenario, is studied in detail. In this case, there are twenty six quadratic divergences, and all these divergences are cancelled provided that one single relation between the masses is satisfied. This mass relation contains a great deal of information, and in particular determines the masses of all the right-handed scalar quarks and scalar leptons, while gives relations for the masses of the left-handed ones. An alternative procedure is also given with a different starting point and less reliance on the experimental data. The result is of course the same.

Yang–Mills gauge theory and Higgs particle

2015 ◽  
Vol 30 (34) ◽  
pp. 1530065
Author(s):  
Tai Tsun Wu ◽  
Sau Lan Wu
Keyword(s):  
Experimental Data ◽  
Gauge Theory ◽  
Standard Model ◽  
Atlas Collaboration ◽  
Higgs Particle ◽  
Abelian Gauge ◽  
Yang Mills ◽  
The Right ◽  
The Masses

Motivated by the experimental data on the Higgs particle from the ATLAS Collaboration and the CMS Collaboration at CERN, the standard model, which is a Yang–Mills non-Abelian gauge theory with the group [Formula: see text], is augmented by scalar quarks and scalar leptons without changing the gauge group and without any additional Higgs particle. Thus there is fermion–boson symmetry between these new particles and the known quarks and leptons. In a simplest scenario, the cancellation of the quadratic divergences in this augmented standard model leads to a determination of the masses of all these scalar quarks and scalar leptons. All these masses are found to be less than 100 GeV/c2, and the right-handed scalar neutrinos are especially light. Alterative procedures are given with less reliance on the experimental data, leading to the same conclusions.

scholarly journals The release of the 13 TeV ATLAS Open Data: using open education resources effectively

2020 ◽  
Vol 245 ◽  
pp. 08026
Author(s):  
Leonid Serkin
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
High Energy Physics ◽  
Hadron Collider ◽  
Open Data ◽  
High Energy ◽  
Proton Collision ◽  
Atlas Collaboration ◽  
Data Set ◽  
Starting Point

The ATLAS Collaboration is releasing a new set of proton–proton collision data to the public for educational purposes. The data was collected by the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy √s = 13 TeV during the year 2016 and corresponds to an integrated luminosity of 10 fb−1. This dataset is accompanied by simulated events describing several Standard Model processes, as well as hypothetical Beyond Standard Model signal processes. Associated computing tools are provided to make the analysis of the dataset easily accessible. In the following, we summarise the properties of the 13 TeV ATLAS Open Data set and the available analysis tools. Several examples intended as a starting point for further analysis work by users are shown. The general aim of the dataset and tools released is to provide user-friendly and straightforward interactive interfaces to replicate the procedures used by high-energy-physics researchers and enable users to experience the analysis of particle-physics data in educational environments.

scholarly journals Detailed study of the Λb → Λcτν̄τ decay

2018 ◽  
Vol 33 (29) ◽  
pp. 1850169 ◽  
Author(s):  
E. Di Salvo ◽  
F. Fontanelli ◽  
Z. J. Ajaltouni
Keyword(s):  
Standard Model ◽  
Semileptonic Decay ◽  
Form Factors ◽  
Higgs Doublet ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Left Handed ◽  
The Standard Model ◽  
Analogous Formula ◽  
Two Higgs Doublet Model

We examine in detail the semileptonic decay [Formula: see text], which may confirm previous hints, from the analogous [Formula: see text] decay, of a new physics beyond the Standard Model. First of all, starting from rather general assumptions, we predict the partial width of the decay. Then we analyze the effects of five possible new physics interactions, adopting in each case five different form factors. In particular, for each term beyond the Standard Model, we find some constraints on the strength and phase of the coupling, which we combine with those found by other authors in analyzing the analogous semileptonic decays of [Formula: see text]. Our analysis involves some dimensionless quantities, substantially independent of the form factor, but which, owing to the constraints, turn out to be strongly sensitive to the kind of nonstandard interaction. We also introduce a criterion thanks to which one can discriminate among the various new physics terms: the left-handed current and the two-Higgs-doublet model appear privileged, with a neat preference for the former interaction. Finally, we suggest a differential observable that could, in principle, help to distinguish between the two cases.

The Discovery of a Higgs Particle at the Large Hadron Collider

2015 ◽  
Vol 23 (1) ◽  
pp. 57-70
Author(s):  
Aleandro Nisati
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Standard Model ◽  
Particle Physics ◽  
Hadron Collider ◽  
Scientific Programme ◽  
Fundamental Particle ◽  
The Standard Model ◽  
8 Tev ◽  
The Masses

The Large Hadron Collider (LHC) at CERN is the highest energy machine for particle physics research ever built. In the years 2010–2012 this accelerator has collided protons to a centre-mass-energy up to 8 TeV (note that 1 TeV corresponds to the energy of about 1000 protons at rest; the mass of one proton is about 1.67×10–24 g). The events delivered by the LHC have been collected and analysed by four apparatuses placed alongside this machine. The search for the Higgs boson predicted by the Standard Model and the search for new particles and fields beyond this theory represent the most important points of the scientific programme of the LHC. In July 2012, the international collaborations ATLAS and CMS, consisting of more than 3000 physicists, announced the discovery of a new neutral particle with a mass of about 125 GeV, whose physics properties are compatible, within present experimental and theoretical uncertainties, to the Higgs boson predicted by the Standard Model. This discovery represents a major milestone for particle physics, since it indicates that the hypothesized Higgs mechanism seems to be responsible for the masses of elementary particles, in particular W± and Z0 bosons, as well as fermions (leptons and quarks). The 2013 Physics Nobel Prize has been assigned to F. Englert and P. Higgs, ‘for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider’.

scholarly journals Brief history for the search and discovery of the Higgs particle — A personal perspective

2014 ◽  
Vol 29 (27) ◽  
pp. 1430062 ◽  
Author(s):  
Sau Lan Wu
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Physics Education ◽  
Particle Physics ◽  
Hadron Collider ◽  
Personal Perspective ◽  
Atlas Collaboration ◽  
Higgs Particle ◽  
History Of ◽  
The Masses

In 1964, a new particle was proposed by several groups to answer the question of where the masses of elementary particles come from; this particle is usually referred to as the Higgs particle or the Higgs boson. In July 2012, this Higgs particle was finally found experimentally, a feat accomplished by the ATLAS Collaboration and the CMS Collaboration using the Large Hadron Collider at CERN. It is the purpose of this review to give my personal perspective on a brief history of the experimental search for this particle since the '80s and finally its discovery in 2012. Besides the early searches, those at the LEP collider at CERN, the Tevatron Collider at Fermilab, and the Large Hadron Collider at CERN are described in some detail. This experimental discovery of the Higgs boson is often considered to be one of the most important advances in particle physics in the last half a century, and some of the possible implications are briefly discussed. This review is based on a talk presented by the author at the conference "OCPA8 International Conference on Physics Education and Frontier Physics," the 8th Joint Meeting of Chinese Physicists Worldwide, Nanyang Technological University, Singapore, June 23–27, 2014.

scholarly journals Interpretation of LHC excesses in ditop and ditau channels as a 400-GeV pseudoscalar resonance

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Ernesto Arganda ◽  
Leandro Da Rold ◽  
Daniel A. Díaz ◽  
Anibal D. Medina
Keyword(s):  
Particle Physics ◽  
Center Of Mass ◽  
Higgs Doublet ◽  
New Physics ◽  
Atlas Collaboration ◽  
Final State ◽  
Center Of Mass Energy ◽  
Heavy Resonances ◽  
Phenomenological Perspective ◽  
The Look

Abstract Since the discovery in 2012 of the Higgs boson at the LHC, as the last missing piece of the Standard Model of particle physics, any hint of new physics has been intensively searched for, with no confirmation to date. There are however slight deviations from the SM that are worth investigating. The CMS collaboration has reported, in a search for heavy resonances decaying in t$$ \overline{t} $$ t ¯ with a 13-TeV center-of-mass energy and a luminosity of 35.9 fb−1, deviations from the SM predictions at the 3.5σ level locally (1.9σ after the look-elsewhere effect). In addition, in the ditau final state search performed by the ATLAS collaboration at $$ \sqrt{s} $$ s = 13 TeV and $$ \mathcal{L} $$ L = 139 fb−1, deviations from the SM at the 2σ level have been also observed. Interestingly, both slight excesses are compatible with a new pseudoscalar boson with a mass around 400 GeV that couples at least to fermions of the third generation and gluons. Starting from a purely phenomenological perspective, we inspect the possibility that a 400-GeV pseudoscalar can account for these deviations and at the same time satisfy the constraints on the rest of the channels that it gives contributions to and that are analyzed by the ATLAS and CMS experiments. After obtaining the range of effective couplings compatible with all experimental measurements, we study the gauge invariant UV completions that can give rise to this type of pseudoscalar resonance, which can be accommodated in an SO(6)/SO(5) model with consistency at the 1σ level and in a SO(5) × U(1)P × U(1)X/SO(4) × U(1)X at the 2σ level, while exceedingly large quartic couplings would be necessary to account for it in a general two Higgs doublet model.

scholarly journals Pembangkitan Massa Medan Skalar dan Boson Tera pada Model Simetri Kiri Kanan Termodifikasi Berdasarkan Grup Tera SU(3)_C⊗SU(2)_L⊗SU(2)_R⊗U(1)_Y

Jurnal Fisika ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 35-41
Author(s):  
Istikomah Istikomah Istikomah
Keyword(s):  
Standard Model ◽  
Gauge Group ◽  
Scalar Fields ◽  
Gauge Bosons ◽  
Symmetry Model ◽  
Particle Pairs ◽  
The Right ◽  
The Masses ◽  
Two Sectors

Modified Left-Right Symmetry Model has been constructed based on  the gauge group . In this model there is a left sector consisting of Standard Model particles with the addition of right-handed neutrino  and the doublet scalar , while the particle pairs are in the right sector. In addition, also added scalar fields  and  which can be intermediaries of interaction between the two sectors. Scalar fields masses can be generated via scalar potensial with the result that   . Whereas the mass of charged gauge bosons , the masses of neutral gauge bosons masses and the mass of photon is zero.

scholarly journals A COMPREHENSIVE MECHANISM REPRODUCING THE MASS AND MIXING PARAMETERS OF QUARKS AND LEPTONS

2013 ◽  
Vol 28 (16) ◽  
pp. 1350070 ◽  
Author(s):  
MICHAEL J. BAKER ◽  
JOSÉ BORDES ◽  
HONG-MO CHAN ◽  
SHEUNG TSUN TSOU
Keyword(s):  
Mass Matrix ◽  
Ckm Matrix ◽  
Changing Scale ◽  
Mixing Parameters ◽  
Starting Point ◽  
Rank One ◽  
Experimental Errors ◽  
Experimental Values ◽  
The Right ◽  
The Masses

It is shown that if, from the starting point of a universal rank-one mass matrix long favored by phenomenologists, one adds the assumption that it rotates (changes its orientation in generation space) with changing scale, one can reproduce, in terms of only six real parameters, all the 16 mass ratios and mixing parameters of quarks and leptons. Of these 16 quantities so reproduced, 10 for which data exist for direct comparison (i.e. the CKM elements including the CP-violating phase, the angles θ12, θ13, θ23 in ν-oscillation, and the masses mc, mμ, me) agree well with experiment, mostly to within experimental errors; four others (ms, mu, md, mν2), the experimental values for which can only be inferred, agree reasonably well; while two others (mν1, δ CP for leptons), not yet measured experimentally, remain as predictions. In addition, one gets as bonuses, estimates for (i) the right-handed neutrino mass mνR and (ii) the strong CP angle θ inherent in QCD. One notes in particular that the output value for sin 2 2 θ13 from the fit agrees very well with recent experiments. By inputting the current experimental value with its error, one obtains further from the fit two new testable constraints: (i) that θ23 must depart from its "maximal" value: sin 2 2 θ23 ~ 0.935 ±0.021, (ii) that the CP-violating (Dirac) phase in the PMNS would be smaller than in the CKM matrix: of order only | sin δ CP | ≤ 0.31 if not vanishing altogether.

scholarly journals HEAVY MAJORANA NEUTRINOS IN e-e- COLLISIONS

1998 ◽  
Vol 13 (14) ◽  
pp. 2363-2381 ◽  
Author(s):  
CHRISTOPH GREUB ◽  
PETER MINKOWSKI
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Majorana Neutrino ◽  
Low Energy ◽  
Left Handed ◽  
Mixing Parameters ◽  
Heavy Majorana Neutrino ◽  
The Standard Model ◽  
Majorana Neutrinos ◽  
The Masses

We discuss the process e-e-→W-W- mediated by heavy Majorana neutrino exchange in the t- and u channel. In our model the cross section for this reaction is a function of the masses (mN) of the heavy Majorana neutrinos and mixing parameters (UeN) originating from mixing between the ordinary left-handed standard model neutrinos and additional singlet right-handed neutrino fields. Taking into account the standard model background and constraints from low energy measurements, we present discovery limits in the [Formula: see text] plane. We also discuss how to measure in principle the CP violating phases, i.e., the relative phases between the mixing parameters.

scholarly journals Brief history for the search and discovery of the Higgs particle – A personal perspective

2014 ◽  
Vol 29 (09) ◽  
pp. 1330027 ◽  
Author(s):  
Sau Lan Wu
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Particle Physics ◽  
Hadron Collider ◽  
Personal Perspective ◽  
Atlas Collaboration ◽  
Higgs Particle ◽  
History Of ◽  
Quo Vadis ◽  
The Masses

In 1964, a new particle was proposed by several groups to answer the question of where the masses of elementary particles come from; this particle is usually referred to as the Higgs particle or the Higgs boson. In July 2012, this Higgs particle was finally found experimentally, a feat accomplished by the ATLAS Collaboration and the CMS Collaboration using the Large Hadron Collider at CERN. It is the purpose of this review to give my personal perspective on a brief history of the experimental search for this particle since the '80s and finally its discovery in 2012. Besides the early searches, those at the LEP collider at CERN, the Tevatron Collider at Fermilab, and the Large Hadron Collider at CERN are described in some detail. This experimental discovery of the Higgs boson is often considered to be the most important advance in particle physics in the last half a century, and some of the possible implications are briefly discussed. This review is partially based on a talk presented by the author at the conference "Higgs Quo Vadis," Aspen Center for Physics, Aspen, CO, USA, March 10–15, 2013.

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