scholarly journals Heavy neutrino searches at future Z-factories

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Jian-Nan Ding ◽  
Qin Qin ◽  
Fu-Sheng Yu
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
Upper Bounds ◽  
Minimal Extension ◽  
Neutrino Sector ◽  
Mixing Parameters ◽  
The Standard Model ◽  
Background Events ◽  
Sigma E ◽  
Two Jets

Abstract We analyze the capacity of future Z-factories to search for heavy neutrinos with their mass from 10 to 85 GeV. The heavy neutrinos N are considered to be produced via the process $$e^+e^-\rightarrow Z\rightarrow \nu N$$e+e-→Z→νN and to decay into an electron or muon and two jets. By means of Monte Carlo simulation of such signal events and the Standard Model background events, we obtain the upper bounds on the cross sections $$\sigma (e^+e^-\rightarrow \nu N\rightarrow \nu \ell jj)$$σ(e+e-→νN→νℓjj) given by the Z-factories with integrated luminosities of 0.1, 1 and 10 $$\hbox {ab}^{-1}$$ab-1 if no signal events are observed. Under the assumption of a minimal extension of the Standard Model in the neutrino sector, we also present the corresponding constraints on the mixing parameters of the heavy neutrinos with the Standard Model leptons, and find they are improved by at least one order compared to current experimental constraints.

scholarly journals Differential cross-section measurements for the electroweak production of dijets in association with a Z boson in proton–proton collisions at ATLAS

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Standard Model ◽  
Differential Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Azimuthal Angle ◽  
Proton Proton ◽  
Weak Boson ◽  
The Standard Model ◽  
Two Jets

AbstractDifferential cross-section measurements are presented for the electroweak production of two jets in association with a Z boson. These measurements are sensitive to the vector-boson fusion production mechanism and provide a fundamental test of the gauge structure of the Standard Model. The analysis is performed using proton–proton collision data collected by ATLAS at $$\sqrt{s}=13\ \hbox {TeV}$$ s = 13 TeV and with an integrated luminosity of $$139\ \hbox {fb}^{-1}$$ 139 fb - 1 . The differential cross-sections are measured in the $$Z\rightarrow \ell ^+\ell ^-$$ Z → ℓ + ℓ - decay channel ($$\ell =e,\mu $$ ℓ = e , μ ) as a function of four observables: the dijet invariant mass, the rapidity interval spanned by the two jets, the signed azimuthal angle between the two jets, and the transverse momentum of the dilepton pair. The data are corrected for the effects of detector inefficiency and resolution and are sufficiently precise to distinguish between different state-of-the-art theoretical predictions calculated using Powheg+Pythia8, Herwig7+Vbfnlo and Sherpa 2.2. The differential cross-sections are used to search for anomalous weak-boson self-interactions using a dimension-six effective field theory. The measurement of the signed azimuthal angle between the two jets is found to be particularly sensitive to the interference between the Standard Model and dimension-six scattering amplitudes and provides a direct test of charge-conjugation and parity invariance in the weak-boson self-interactions.

scholarly journals THE THIRD TYPE OF FERMION MIXING IN THE LEPTON AND QUARK INTERACTIONS WITH LEPTOQUARKS

2012 ◽  
Vol 27 (11) ◽  
pp. 1250062 ◽  
Author(s):  
A. V. KUZNETSOV ◽  
N. V. MIKHEEV ◽  
A. V. SERGHIENKO
Keyword(s):  
Lower Bound ◽  
Standard Model ◽  
Low Energy ◽  
Minimal Extension ◽  
The Third ◽  
Model Based ◽  
Mixing Parameters ◽  
The Standard Model

The low-energy manifestations of a minimal extension of the electroweak standard model based on the quark–lepton symmetry SU(4)V ⊗SU(2)L ⊗GR of the Pati–Salam-type are analyzed. Given this symmetry the third type of mixing in the interactions of the SU(4)V leptoquarks with quarks and leptons is shown to be required. An additional arbitrariness of the mixing parameters could allow, in principle, to decrease noticeably the lower bound on the vector leptoquark mass originated from the low-energy rare processes, strongly suppressed in the standard model.

scholarly journals Effective operator bases for beyond Standard Model scenarios: an EFT compendium for discoveries

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Upalaparna Banerjee ◽  
Joydeep Chakrabortty ◽  
Suraj Prakash ◽  
Shakeel Ur Rahaman ◽  
Michael Spannowsky
Keyword(s):  
Standard Model ◽  
High Energy ◽  
Beyond The Standard Model ◽  
Minimal Extension ◽  
Effective Operator ◽  
Abelian Gauge ◽  
Gauge Symmetries ◽  
Higher Dimensional ◽  
The Standard Model ◽  
Mass Dimension

Abstract It is not only conceivable but likely that the spectrum of physics beyond the Standard Model (SM) is non-degenerate. The lightest non-SM particle may reside close enough to the electroweak scale that it can be kinematically probed at high-energy experiments and on account of this, it must be included as an infrared (IR) degree of freedom (DOF) along with the SM ones. The rest of the non-SM particles are heavy enough to be directly experimentally inaccessible and can be integrated out. Now, to capture the effects of the complete theory, one must take into account the higher dimensional operators constituted of the SM DOFs and the minimal extension. This construction, BSMEFT, is in the same spirit as SMEFT but now with extra IR DOFs. Constructing a BSMEFT is in general the first step after establishing experimental evidence for a new particle. We have investigated three different scenarios where the SM is extended by additional (i) uncolored, (ii) colored particles, and (iii) abelian gauge symmetries. For each such scenario, we have included the most-anticipated and phenomenologically motivated models to demonstrate the concept of BSMEFT. In this paper, we have provided the full EFT Lagrangian for each such model up to mass dimension 6. We have also identified the CP, baryon (B), and lepton (L) number violating effective operators.

scholarly journals Chiral anomaly in SU(2)R-axion inflation and the new prediction for particle cosmology

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Azadeh Maleknejad
Keyword(s):  
Standard Model ◽  
Symmetry Breaking ◽  
Particle Physics ◽  
Cosmological Parameters ◽  
Chiral Anomaly ◽  
Dark Matter Candidate ◽  
Neutrino Sector ◽  
Matter Creation ◽  
The Standard Model ◽  
Non Gaussian

Abstract Upon embedding the axion-inflation in the minimal left-right symmetric gauge extension of the SM with gauge group SU(2)L × SU(2)R × U(1)B−L, [1] proposed a new particle physics model for inflation. In this work, we present a more detailed analysis. As a compelling consequence, this setup provides a new mechanism for simultaneous baryogenesis and right-handed neutrino creation by the chiral anomaly of WR in inflation. The lightest right-handed neutrino is the dark matter candidate. This setup has two unknown fundamental scales, i.e., the scale of inflation and left-right symmetry breaking SU(2)R × U(1)B−L→ U(1)Y. Sufficient matter creation demands the left-right symmetry breaking scale happens shortly after the end of inflation. Interestingly, it prefers left-right symmetry breaking scales above 1010 GeV, which is in the range suggested by the non-supersymmetric SO(10) Grand Unified Theory with an intermediate left-right symmetry scale. Although WR gauge field generates equal amounts of right-handed baryons and leptons in inflation, i.e. B − L = 0, in the Standard Model sub-sector B − LSM ≠ 0. A key aspect of this setup is that SU(2)R sphalerons are never in equilibrium, and the primordial B − LSM is conserved by the Standard Model interactions. This setup yields a deep connection between CP violation in physics of inflation and matter creation (visible and dark); hence it can naturally explain the observed coincidences among cosmological parameters, i.e., ηB ≃ 0.3Pζ and ΩDM ≃ 5ΩB. The new mechanism does not rely on the largeness of the unconstrained CP-violating phases in the neutrino sector nor fine-tuned masses for the heaviest right-handed neutrinos. The SU(2)R-axion inflation comes with a cosmological smoking gun; chiral, non-Gaussian, and blue-tilted gravitational wave background, which can be probed by future CMB missions and laser interferometer detectors.

TeV Scale B – L Phenomenology at LHC

2007 ◽  
Vol 22 (31) ◽  
pp. 5889-5908 ◽  
Author(s):  
M. Abbas ◽  
W. Emam ◽  
S. Khalil ◽  
M. Shalaby
Keyword(s):  
Standard Model ◽  
Gauge Boson ◽  
Cross Sections ◽  
Branching Ratios ◽  
Higgs Production ◽  
Neutrino Masses ◽  
Natural Explanation ◽  
The Standard Model ◽  
The Cross

We present the phenomenology of the low scale U(1)B–L extension of the standard model and its implications at LHC. We show that this model provides a natural explanation for the presence of three right-handed neutrinos and can naturally account the observed neutrino masses and mixing. We study the decay and production of the extra gauge boson and the SM singlet scalar (heavy Higgs) predicted in this type of models. We find that the cross sections of the SM-like Higgs production are reduced by ~ 20% – 30%, while its decay branching ratios remain intact. The extra Higgs has relatively small cross sections and the branching ratios of Z′ → l+l− are of order ~ 20% compared to ~ 3% of the SM results.

scholarly journals W-boson production in the high energy electron-photon collisions

2019 ◽  
pp. 41-50
Author(s):  
Ivan A. Shershan ◽  
Tatiana V. Shishkina
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
W Boson ◽  
High Energy ◽  
New Physics ◽  
Coupling Constants ◽  
Boson Production ◽  
The Standard Model ◽  
Electron Photon ◽  
W Boson Production

In this paper the analysis of W-boson production process in high-energy electron-photon collisions as a tool to search for deviations from the Standard Model is considered. In particular, a set of extended gauge models, including anomalous multi-boson interactions, are discussed as a promising way for «new physics» study. A numerical analysis of the total cross sections of the processes was carried out. The lowest order radiative corrections in the soft-photon approximation within the Standard Model are taken into account. Calculations beyond the Standard Model was performed, the kinematic features of the cross sections were identified. The restrictions on the anomalous triple gauge boson coupling constants were analyzed and the kinematic areas to the search for their manifestations were obtained during the experiments at the International Linear Collider. The paper shows that the search for «new physics» effects based on electron-photon collisions around the W-boson production peak is the maximal promising. It was also shown that future experiments at high luminosity linear colliders will significantly clarify the constraints on anomalous gauge coupling constants.

Chapter 6 R Values and Precise Test of the Standard Model

2009 ◽  
Vol 24 (supp01) ◽  
pp. 111-132 ◽  
Author(s):  
Hai-Ming Hu ◽  
Xiao-Yuan Li
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
Vacuum Polarization ◽  
The Standard Model ◽  
Input Parameters ◽  
R Value

The following sections are included: e+e- → hadrons Cross Sections and the Rhad Value Hadronic Vacuum Polarization Input Parameters and their Uncertainties Measurement of R Value at BES-III

EFFECTS OF AN EXTRA NEUTRAL E6 GAUGE BOSON IN e+e− ANNIHILATION INTO HADRONS

1988 ◽  
Vol 03 (12) ◽  
pp. 2959-2970
Author(s):  
F. CSIKOR ◽  
E. LENDVAI ◽  
G. PÓCSIK
Keyword(s):  
Standard Model ◽  
Gauge Boson ◽  
Cross Sections ◽  
Total Cross Sections ◽  
The Standard Model ◽  
Azimuthal Asymmetries

We calculate the influence of an extra neutral E6 gauge boson on the energy weighted and total cross sections in e+e− annihilation into hadrons. Longitudinal and azimuthal asymmetries are sensitive to the various extra U(1) factors and can show noticeable deviations from the standard model.

scholarly journals Synthesis on Heavy Higgs from the Standard Model to 2HDM and Beyond

2020 ◽  
Vol 18 ◽  
pp. 110-142
Author(s):  
Abdeljalil Habjia
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Sections ◽  
Particle Physics ◽  
Hadron Collider ◽  
Signal Strength ◽  
Beyond The Standard Model ◽  
Decay Channels ◽  
Higgs Decay ◽  
The Standard Model

In the context of particle physics, within the ATLAS and CMS experiments at large hadron collider (LHC), this work presents the discussion of the discovery of a particle compatible with the Higgs boson by the combination of several decay channels, with a mass of the order of 125.5 GeV. With increased statistics, that is the full set of data collected by the ATLAS and CMS experiments at LHC ( s1/2 = 7GeV and s1/2 = 8GeV ), the particle is also discovered individually in the channel h-->γγ with an observed significance of 5.2σ and 4.7σ, respectively. The analysis dedicated to the measurement of the mass mh and signal strength μ which is defined as the ratio of σ(pp --> h) X Br(h-->X) normalized to its Standard Model where X = WW*; ZZ*; γγ ; gg; ff. The combined results in h-->γγ channel gave the measurements: mh = 125:36 ± 0:37Gev, (μ = 1:17 ± 0:3) and the constraint on the width Γ(h) of the Higgs decay of 4.07 MeV at 95%CL. The spin study rejects the hypothesis of spin 2 at 99 %CL. The odd parity (spin parity 0- state) is excluded at more than 98%CL. Within the theoretical and experimental uncertainties accessible at the time of the analysis, all results: channels showing the excess with respect to the background-only hypothesis, measured mass and signal strength, couplings, quantum numbers (JPC), production modes, total and differential cross-sections, are compatible with the Standard Model Higgs boson at 95%CL. Although the Standard Model is one of the theories that have experienced the greatest number of successes to date, it is imperfect. The inability of this model to describe certain phenomena seems to suggest that it is only an approximation of a more general theory. Models beyond the Standard Model, such as 2HDM, MSSM or NMSSM, can compensate some of its limitations and postulate the existence of additional Higgs bosons.

scholarly journals High-energy neutrino interaction physics with IceCube

2019 ◽  
Vol 208 ◽  
pp. 09001
Author(s):  
Spencer Klein
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
Neutrino Flux ◽  
High Energy ◽  
Neutrino Interaction ◽  
Neutrino Telescopes ◽  
Neutrino Interactions ◽  
The Standard Model ◽  
Astrophysical Neutrinos ◽  
Neutrino Absorption

Although they are best known for studying astrophysical neutrinos, neutrino telescopes like IceCube can study neutrino interactions, at energies far above those that are accessible at accelerators. In this writeup, I present two IceCube analyses of neutrino interactions at energies far above 1 TeV. The first measures neutrino absorption in the Earth, and, from that determines the neutrino-nucleon cross-section at energies between 6.3 and 980 TeV. We find that the cross-sections are 1.30 +0.21 -0.19 (stat.) +0.39 -0.43 (syst.) times the Standard Model crosssection. We also present a measurement of neutrino inelasticity, using νμ charged-current interactions that occur within IceCube. We have measured the average inelasticity at energies from 1 TeV to above 100 TeV, and found that it is in agreement with the Standard Model expectations. We have also performed a series of fits to this track sample and a matching cascade sample, to probe aspects of the astrophysical neutrino flux, particularly the flavor ratio.

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