Xerxes Tata

Updated Constraints on the Minimal Supergravity Model

Recently, refinements have been made on both the theoretical and experimental determinations of i.) the mass of the lightest Higgs scalar (mh), ii.) the relic density of cold dark matter in the universe (ΩCDMh 2), iii.) the branching fraction for radiative B decay BF (b → sγ), iv.) the muon anomalous magnetic moment (aμ), and v.) the flavor violating decay Bs → μ+μ−. Each of these quantities can be predicted in the MSSM, and each depends in a non-trivial way on the spectra of SUSY particles. In this paper, we present updated constraints from each of these quantities on the minimal supergravity (mSUGRA) model as embedded in the computer program ISAJET. The combination of constraints points to certain favored regions of model parameter space where collider and non-accelerator SUSY searches may be more focussed.We provide an up-to-date analysis of the parameter space of the minimal supergravity model (mSUGRA). Novel features include the new central value of the top quark mass, an improved calculation of the masses of the supersymmetric particles and the neutral Higgs bosons, constraints from b→sl+l− decays, and a careful treatment of the most important experimental and theoretical uncertainties. In addition to the by now traditional plots of the allowed region in the (m0,m1/2) plane, we show allowed regions in the planes spanned by pairs of physical sparticle or Higgs boson masses. Moreover, we search for the minimal allowed masses of new particles for various sets of constraints. We find that in many cases the direct experimental limits from collider and Dark Matter searches can be saturated even in this minimal model, and even after including the by now quite restrictive constraint on the Dark Matter relic density.

Direct, indirect and collider detection of neutralino dark matter in SUSY models with non-universal Higgs masses

In supersymmetric models with gravity-mediated SUSY breaking, universality of soft SUSY breaking sfermion masses m0 is motivated by the need to suppress unwanted flavor changing processes. The same motivation, however, does not apply to soft breaking Higgs masses, which may in general have independent masses from matter scalars at the GUT scale. We explore phenomenological implications of both the one-parameter and two-parameter non-universal Higgs mass models (NUHM1 and NUHM2), and examine the parameter ranges compatible with ΩCDMh2, BF(b→sγ) and (g−2)μ constraints. We have demonstrated that in contrast to the mSUGRA model, in both NUHM1 and NUHM2 models, the dark matter A-annihilation funnel can be reached at low values of tan β, while the higgsino dark matter annihilation regions can be reached for low values of m0. We show that there may be observable rates for indirect and direct detection of neutralino cold dark matter in phenomenologically aceptable ranges of parameter space. We also examine implications of the NUHM models for the Fermilab Tevatron, the CERN LHC and a (s)1/2 = 0.5−1 TeV e+e− linear collider. Novel possibilities include: very light R, R squark and L slepton masses as well as light charginos and neutralinos and H, A and H± Higgs bosons.

Radiative natural supersymmetry with a 125 GeV Higgs boson.

It has been argued that requiring low electroweak fine-tuning (EWFT) along with a (partial) decoupling solution to the supersymmetry (SUSY) flavor and CP problems leads to a sparticle mass spectra characterized by light Higgsinos at 100-300 GeV, sub-TeV third generation scalars, gluinos at a few TeV, and multi-TeV first or second generation scalars (natural SUSY). We show that by starting with multi-TeV first or second and third generation scalars and trilinear soft breaking terms, the natural SUSY spectrum can be generated radiatively via renormalization group running effects. Using the complete 1-loop effective potential to calculate EWFT, significantly heavier third generation squarks can be allowed even with low EWFT. The large negative trilinear term and heavier top squarks allow for a light Higgs scalar in the ~125 GeV regime.

Updated reach of CERN LHC and constraints from relic density, b→sγ and aμ in the mSUGRA model

We present an updated assessment of the reach of the CERN LHC pp collider for supersymmetric matter in the context of the minimal supergravity (mSUGRA) model. In addition to previously examined channels, we also include signals with an isolated photon or with a leptonically decaying Z boson. For an integrated luminosity of 100 fb−1, values of m1/2 ~ 1400 GeV can be probed for small m0, corresponding to a gluino mass of m ~ 3 TeV. For large m0, in the hyperbolic branch/focus point region, m1/2 ~ 700 GeV can be probed, corresponding to m ~ 1800 GeV. We also map out parameter space regions preferred by the measured values of the dark matter relic density, the b→sγ decay rate, and the muon anomalous magnetic moment aμ, and discuss how SUSY might reveal itself in these regions. We find the CERN LHC can probe the entire stau co-annihilation region and also most of the heavy Higgs annihilation funnel allowed by WMAP data, except for some range of large m0 and m1/2 if tan β50.

b→Sγ Constraints on the Minimal Supergravity Model with Large tanβ

In the minimal supergravity model (mSUGRA), as the parameter

Radiative natural supersymmetry: Reconciling electroweak fine-tuning and the Higgs boson mass

\tan\beta

Neutralino cold dark matter in a one-parameter extension of the minimal supergravity model

increases, the charged Higgs boson and light bottom squark masses decrease, which can potentially increase contributions from

Probing minimal supergravity at the CERN LHC for large tan Beta

tH^\pm

Post-LHC7 fine-tuning in the minimal supergravity/CMSSM model with a 125 GeV Higgs boson

,

Natural supersymmetry: LHC, dark matter and ILC searches

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