NUMERICAL ANALYSIS OF GUTs PREDICTIONS IN THE LIGHT OF RECENT RESULTS FROM LEP

1992 ◽  
Vol 07 (35) ◽  
pp. 3319-3330
Author(s):  
DARIUSZ GRECH
Keyword(s):  
Z Boson ◽  
Electromagnetic Coupling ◽  
Boson Mass ◽  
Threshold Effects ◽  
Coupling Constant ◽  
Central Values ◽  
Unified Theories ◽  
Proton Lifetime ◽  
Experimental Values ◽  
Best Fit

We find numerical best fit for sin 2 Θw(MZ), unifying mass MX and the proton lifetime τp as the outcome of analysis where experimental values of Z boson mass MZ, strong coupling constant αs(MZ) and electromagnetic coupling α0(MZ) are taken as the only input parameters. It is found that simple nonsupersymmetric models are unlikely to be realistic ones. On the other hand, we find the best numerical fit: sin 2Θw(MZ = 0.2330 ± 0.0007 (theor.) ± 0.0027 (exp.) , [Formula: see text] yr for supersymmetric unified theories with three generations. The central values require, however, that the supersymmetric mass Λs≲300 GeV . Possibilities of increasing this limit as well as cases with four generations and threshold effects are also discussed. Compact formulas for theoretical and experimental uncertainties involved in the analysis are also produced.

Strong coupling constant from Adler function in lattice QCD

2016 ◽  
Vol 31 (32) ◽  
pp. 1630037
Author(s):  
Renwick J. Hudspith ◽  
Randy Lewis ◽  
Kim Maltman ◽  
Eigo Shintani
Keyword(s):  
Z Boson ◽  
Statistical Error ◽  
Vector Current ◽  
Boson Mass ◽  
Coupling Constant ◽  
Lattice Data ◽  
Momentum Scale ◽  
Local Vector ◽  
Global Fit ◽  
Adler Function

We compute the QCD coupling constant, [Formula: see text], from the Adler function with vector hadronic vacuum polarization (HVP) function. On the lattice, Adler function can be measured by the differential of HVP at two different momentum scales. HVP is measured from the conserved-local vector current correlator using nf = 2 + 1 flavor Domain Wall lattice data with three different lattice cutoffs, up to a[Formula: see text] 3.14 GeV. To avoid the lattice artifact due to O(4) symmetry breaking, we set the cylinder cut on the lattice momentum with reflection projection onto vector current correlator, and it then provides smooth function of momentum scale for extracted HVP. We present a global fit of the lattice data at a justified momentum scale with three lattice cutoffs using continuum perturbation theory at [Formula: see text] to obtain the coupling in the continuum limit at arbitrary scale. We take the running to Z boson mass through the appropriate thresholds, and obtain [Formula: see text](MZ) = 0.1191(24)(37) where the first is statistical error and the second is systematic one.

scholarly journals The LHC Higgs boson discovery: Implications for Finite Unified Theories

2014 ◽  
Vol 29 (18) ◽  
pp. 1430032 ◽  
Author(s):  
S. Heinemeyer ◽  
M. Mondragón ◽  
G. Zoupanos
Keyword(s):  
Higgs Boson ◽  
Predictive Power ◽  
Low Energy ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Light Higgs Boson ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Discovery Potential

Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories (GUTs) which can be made finite to all-loop orders, based on the principle of reduction of couplings, and therefore are provided with a large predictive power. We confront the predictions of an SU(5) FUT with the top and bottom quark masses and other low-energy experimental constraints, resulting in a relatively heavy SUSY spectrum, naturally consistent with the nonobservation of those particles at the LHC. The light Higgs boson mass is automatically predicted in the range compatible with the Higgs discovery at the LHC. Requiring a light Higgs boson mass in the precise range of Mh= 125.6 ±2.1 GeV favors the lower part of the allowed spectrum, resulting in clear predictions for the discovery potential at current and future pp, as well as future e+e-colliders.

scholarly journals On the running electromagnetic coupling constant at $M_Z$

1999 ◽  
Vol 9 (4) ◽  
pp. 551-556 ◽  
Author(s):  
J.G. Körner ◽  
A.A. Pivovarov ◽  
K. Schilcher
Keyword(s):  
Electromagnetic Coupling ◽  
Coupling Constant

scholarly journals Cross Section Prediction for Inclusive Production of Z Boson in pp Collisions at s=14 TeV: A Study of Systematic Uncertainty due to Scale Dependence

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Hasan Ogul ◽  
Kamuran Dilsiz
Keyword(s):  
Cross Section ◽  
Production Cross Section ◽  
Z Boson ◽  
Production Cross ◽  
Branching Ratio ◽  
Leading Order ◽  
Proton Proton ◽  
Proton Collisions ◽  
Central Values ◽  
Proton Proton Collisions

Prediction of Z→l+l- production cross section (where l±=e±,μ±) in proton-proton collisions at s=14 TeV is estimated up to next-to-next-to-leading order (NNLO) in perturbative QCD including next-to-leading order (NLO) electroweak (EW) corrections. The total inclusive Z boson production cross section times leptonic branching ratio, within the invariant mass window 66<mll<116 GeV, is predicted using NNLO HERAPDF2.0 at NNLO QCD and NLO EW as σZTot=2111.69-26.92+26.31 (PDF) ±11 (αs) ±17 (scale) -30.98+57.41 (parameterization and model). Theoretical prediction of the fiducial cross section is further computed with the latest modern PDF models (CT14, MMHT2014, NNPDF3.0, HERAPDF2.0, and ABM12) at NNLO for QCD and NLO for EW. The central values of the predictions are based on DYNNLO 1.5 program and the uncertainties are extracted using FEWZ 3.1 program. In addition, the cross section is also calculated as functions of μR and μF scales. The choice of μR and μF for scale variation uncertainty is further discussed in detail.

scholarly journals Thermodynamics of Charged Rotating Dilaton Black Branes Coupled to Logarithmic Nonlinear Electrodynamics

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
A. Sheykhi ◽  
M. H. Dehghani ◽  
M. Kord Zangeneh
Keyword(s):  
Thermal Stability ◽  
Electromagnetic Coupling ◽  
Nonlinear Electrodynamics ◽  
Black Brane ◽  
Dilaton Field ◽  
Coupling Constant ◽  
De Sitter ◽  
New Class ◽  
Unstable Phase ◽  
Complete Set

We construct a new class of charged rotating black brane solutions in the presence of logarithmic nonlinear electrodynamics with complete set of the rotation parameters in arbitrary dimensions. The topology of the horizon of these rotating black branes is flat, while due to the presence of the dilaton field the asymptotic behavior of them is neither flat nor (anti-)de Sitter [(A)dS]. We investigate the physical properties of the solutions. The mass and angular momentum of the spacetime are obtained by using the counterterm method inspired by AdS/CFT correspondence. We derive temperature, electric potential, and entropy associated with the horizon and check the validity of the first law of thermodynamics on the black brane horizon. We study thermal stability of the solutions in both canonical and grand-canonical ensemble and disclose the effects of the rotation parameter, nonlinearity of electrodynamics, and dilaton field on the thermal stability conditions. We find the solutions are thermally stable forα<1, while forα>1the solutions may encounter an unstable phase, whereαis dilaton-electromagnetic coupling constant.

scholarly journals Conformal GUT inflation, proton lifetime and non-thermal leptogenesis

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
K. Sravan Kumar ◽  
Paulo Vargas Moniz
Keyword(s):  
Conformal Symmetry ◽  
Lepton Number ◽  
Baryon Asymmetry ◽  
Neutrino Masses ◽  
Type I ◽  
Gauge Bosons ◽  
Seesaw Mechanism ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Proton Lifetime

AbstractIn this paper, we generalize Coleman–Weinberg (CW) inflation in grand unified theories (GUTs) such as $$\text {SU}(5)$$SU(5) and $$\text {SO}(10)$$SO(10) by means of considering two complex singlet fields with conformal invariance. In this framework, inflation emerges from a spontaneously broken conformal symmetry. The GUT symmetry implies a potential with a CW form, as a consequence of radiative corrections. The conformal symmetry flattens the above VEV branch of the CW potential to a Starobinsky plateau. As a result, we obtain $$n_{s}\sim 1-\frac{2}{N}$$ns∼1-2N and $$r\sim \frac{12}{N^2}$$r∼12N2 for $$N\sim $$N∼ 50–60 e-foldings. Furthermore, this framework allow us to estimate the proton lifetime as $$\tau _{p}\lesssim 10^{40}$$τp≲1040 years, whose decay is mediated by the superheavy gauge bosons. Moreover, we implement a type I seesaw mechanism by weakly coupling the complex singlet, which carries two units of lepton number, to the three generations of singlet right handed neutrinos (RHNs). The spontaneous symmetry breaking of global lepton number amounts to the generation of neutrino masses. We also consider non-thermal leptogenesis in which the inflaton dominantly decays into heavy RHNs that sources the observed baryon asymmetry. We constrain the couplings of the inflaton field to the RHNs, which gives the reheating temperature as $$10^{6}\text { GeV}\lesssim T_{R}<10^{9}$$106GeV≲TR<109 GeV.

TESTING SOME PROPERTIES OF NEUTRAL CURRENT NEUTRINO INTERACTIONS IN NEUTRINO COUNTING REACTION

1988 ◽  
Vol 03 (03) ◽  
pp. 721-729 ◽  
Author(s):  
P. RAM BABU
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Z Boson ◽  
Neutral Current ◽  
Z Bosons ◽  
Coupling Constant ◽  
Neutral Currents ◽  
Lorentz Structure ◽  
Neutrino Interactions

We have considered the ‘neutrino counting’ reaction [Formula: see text]. We restrict to V, A Lorentz structure of weak neutral interaction (WNI), allow many Z bosons to mediate WNI and νi to be different from νj. We derive the expression for differential cross section by allowing the polarizations of e+ and e− but summing over the polarizations of final photons. From the study of differential cross section with polarized and unpolarized beams three different coupling constant combinations can be determined. A definite relation between these observables and the observables in [Formula: see text] scatterings is suggested as a test of single-Z-boson hypothesis. Similarly another test relates observables in [Formula: see text] to those of [Formula: see text] scatterings. By assuming universality a test for presence of nondiagonal neutrino neutral currents (NDνNC’s) is also pointed out. The effects of presence of wrong-handed (anti-) neutrinos on our tests are also discussed. As a by-product, we find a way to determine number of neutrino types, in the case i≠j, assuming universality.

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