NEW BOUNDS ON THE HIGGS SECTOR OF MINIMAL SUSY

1990 ◽  
Vol 05 (16) ◽  
pp. 1259-1264 ◽  
Author(s):  
JORGE L. LOPEZ ◽  
D.V. NANOPOULOS

We examine the Higgs sector of the minimal supersymmetric extension of the standard model. The requirement of perturbative unification combined with the recent LEP data on Higgs boson searches, excludes substantial regions of parameter space. We find that only 0.42 ≤ tan β≲0.76 and tan β≳1.30 are the allowed values for tan β=υ2/υ1. We also determine the absolute lower bound on the lightest Higgs mass to be ≈8 GeV. We conclude that improved lower bounds on the top quark mass and/or the standard model Higgs boson mass will impose yet more stringent constraints on the model. These results clearly favor tan β>1, in agreement with N=1 supergravity or superstring-inspired models.

1998 ◽  
Vol 13 (32) ◽  
pp. 2613-2620 ◽  
Author(s):  
KYUNGSIK KANG ◽  
SIN KYU KANG

We argue that the present value and accuracy of MW and mt measurements tend to favor the MSSM, provided that the central values of MW and mt stay at the current values, over the SM. By speculating that a precision of order 40 MeV and 3 GeV respectively for MW and mt will be achieved at LEP2 and Tevatron, we show that the prospect for the MSSM will be further enhanced as long as the central values of MW and mt do not increase below the present values. In addition, we discuss how this scenario can constrain the Higgs boson mass and distinguish the Higgs boson of the MSSM type from that of the SM.


2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Astrid Eichhorn ◽  
Martin Pauly ◽  
Shouryya Ray

Abstract There are indications that an asymptotically safe UV completion of the Standard Model with gravity could constrain the Higgs self-coupling, resulting in a prediction of the Higgs mass close to the vacuum stability bound in the Standard Model. The predicted value depends on the top quark mass and comes out somewhat higher than the experimental value if the current central value for the top quark mass is assumed. Beyond the Standard Model, the predicted value also depends on dark fields coupled through a Higgs portal. Here we study the Higgs self-coupling in a toy model of the Standard Model with quantum gravity that we extend by a dark scalar and fermion. Within the approximations used in [1], there is a single free parameter in the asymptotically safe dark sector, as a function of which the predicted (toy model) Higgs mass can be lowered due to mixing effects if the dark sector undergoes spontaneous symmetry breaking.


2000 ◽  
Vol 15 (16) ◽  
pp. 2605-2611 ◽  
Author(s):  
TOMOMI OHGAKI

We demonstrate a measurement of the Higgs boson mass by the method of energy scanning at photon–photon colliders, using the high energy edge of the photon spectrum. With an integrated luminosity of 50 fb-1 it is possible to measure the standard model Higgs mass to within 110 MeV in photon–photon collisions for mh=100 GeV. As for the total width of the Higgs boson, the statistical error ΔΓh/Γh SM=0.06 is expected for mh=100 GeV, if both Γ(h→γγ) and [Formula: see text] are fixed at the predicted standard model value.


1995 ◽  
Vol 10 (01) ◽  
pp. 1-63 ◽  
Author(s):  
A. DJOUADI

The prospects for discovering Higgs particles and studying their fundamental properties at future high-energy electron-positron and hadron colliders are reviewed. Both the Standard Model Higgs boson and the Higgs particles of its minimal supersymmetric extension are discussed. We update various results by taking into account the new value of the top-quark mass obtained by the CDF Collaboration, and by including radiative corrections, some of which have been calculated only recently.


2010 ◽  
Vol 25 (27n28) ◽  
pp. 5082-5096
Author(s):  
R. SEKHAR CHIVUKULA ◽  
ROSHAN FOADI ◽  
ELIZABETH H. SIMMONS ◽  
STEFANO DI CHIARA

We introduce a toy model implementing the proposal of using a custodial symmetry to protect the [Formula: see text] coupling from large corrections. This "doublet-extended standard model" adds a weak doublet of fermions (including a heavy partner of the top quark) to the particle content of the standard model in order to implement an O(4) × U(1)X ~ SU(2)L × SU(2)R × PLR × U(1)X symmetry in the top-quark mass generating sector. This symmetry is softly broken to the gauged SU(2)L × U(1)Y electroweak symmetry by a Dirac mass M for the new doublet; adjusting the value of M allows us to explore the range of possibilities between the O(4)-symmetric (M → 0) and standard-model-like (M → ∞) limits.


1999 ◽  
Vol 14 (26) ◽  
pp. 1815-1827 ◽  
Author(s):  
J. H. FIELD

A model independent analysis of the most recent averages of precision electroweak data from LEP and SLD finds a 3σ deviation of the parameter Ab from the standard model prediction. The fitted value of mH shows a strong dependence on the inclusion or exclusion of b quark data, and the standard model fits have poor confidence levels of a few percent when the latter are included. The good fits obtained to lepton data, c quark data and the directly measured top quark mass, give [Formula: see text] and indicate that the Higgs boson mass is most likely less than 200 GeV.


1995 ◽  
Vol 10 (29) ◽  
pp. 4241-4264 ◽  
Author(s):  
JORGE L. LOPEZ ◽  
D.V. NANOPOULOS ◽  
A. ZICHICHI

We consider the experimental predictions of two one-parameter no-scale SU (5)× U (1) supergravity models with string-inspired moduli and dilaton seeds of supersymmetry breaking. These predictions have been considerably sharpened with the new information on the top-quark mass from the Tevatron, and the actual measurement of the B(b→sγ) branching ratio from CLEO. In particular, the sign of the Higgs mixing parameter μ is fixed. A more precise measurement of the top-quark mass above (below) ≈160 GeV would disfavor the dilaton (moduli) scenario. Similarly a measurement of the lightest Higgs-boson mass above 90 GeV (below 100 GeV) would disfavor the dilaton (moduli) scenario. At the Tevatron with 100 pb−1, the reach into parameter space is significant only in the dilaton scenario [Formula: see text] via the trilepton and top-squark signals. At LEPII the dilaton scenario could be probed up to the kinematical limit via chargino and top-squark pair production, and the discovery of the lightest Higgs boson is guaranteed. In the moduli scenario, only selectron pair production looks promising. We also calculate the supersymmetric contribution to the anomalous magnetic moment of the muon.


2006 ◽  
Vol 21 (25) ◽  
pp. 1923-1929 ◽  
Author(s):  
E. JURČIŠINOVÁ ◽  
M. JURČIŠIN

We investigate the focus points of the renormalization group equations of the minimal supersymmetric standard model. We show that within this model the up- and down-type Higgs mass soft supersymmetry breaking parameters have focus point behavior at the electroweak scale simultaneously when appropriate conditions are fulfilled. The focus point scenario holds for large tan β. This two-focus-point scenario allows to fix the pole top-quark mass which is within the experimentally allowed interval. The main goal of this paper is the investigation of the influence of the existence of focus points on the determination of the mass of the lightest Higgs boson.


1995 ◽  
Vol 21 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Zhenjun Xiao ◽  
Jinyu Zhang ◽  
Lingde Wan ◽  
Xuelei Wang ◽  
Gongru Lui

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