mSUGRA

mSUGRA
Name	Minimal Supergravity (mSUGRA)
Also known as	CMSSM
Field	Particle physics; Supersymmetry
Introduced	1982
Proponents	Hitoshi Murayama; Howard Georgi; Savas Dimopoulos; Goran Senjanović
Related models	Minimal Supersymmetric Standard Model; Supergravity; Gravity-mediated supersymmetry breaking
Key features	universal soft terms at high scale; radiative electroweak symmetry breaking

mSUGRA mSUGRA is a high-scale framework for supersymmetry breaking that imposes universal boundary conditions on soft terms at a unification scale, producing a constrained spectrum and predictive phenomenology. The construction ties ideas from Grand Unified Theory proposals such as SU(5), SO(10), and E6 to supergravity embedding and was influential in guiding searches at colliders like the Large Hadron Collider, Tevatron, and experiments at LEP. It provides a minimal parameter set used extensively in global fits, dark matter studies, and Monte Carlo simulations motivated by benchmarks from collaborations such as ATLAS and CMS.

Introduction

mSUGRA originated in efforts to connect local supersymmetry with phenomenology via gravity-mediated transmission of supersymmetry breaking from a hidden sector to the Minimal Supersymmetric Standard Model fields. Early theoretical development involved researchers affiliated with institutions like Harvard University, SLAC National Accelerator Laboratory, CERN, and Los Alamos National Laboratory. The model became a common reference in experimental proposals from collaborations including CDF, D0, ALEPH, and theoretical reviews by authors in journals associated with Physical Review D and Nuclear Physics B.

Theoretical Framework

The defining assumption is universal soft parameters at a high input scale often taken near a Grand Unified Theory scale associated with gauge coupling unification in frameworks such as SU(5] or SO(10). The parameter set reduces to a common scalar mass m0, a common gaugino mass m1/2, a common trilinear coupling A0, the ratio of Higgs vacuum expectation values tan(beta), and the sign of the Higgsino mass parameter mu. Radiative electroweak symmetry breaking is driven by renormalization group evolution from the high scale to the electroweak scale, linking to work on running couplings by researchers at CERN and SLAC. Theoretical consistency involves addressing issues discussed in papers from Princeton University and Institute for Advanced Study, and constraints arising from supergravity constructions explored by groups at University of California, Berkeley and MIT.

Phenomenology and Signatures

mSUGRA yields characteristic mass hierarchies that influenced search strategies at the Large Hadron Collider, Tevatron, and LEP. Typical signatures include multijet plus missing transverse energy events exploited by ATLAS and CMS, multilepton final states analyzed by CDF and D0, and rare decay channels studied by LHCb and experiments at Babar and Belle. The lightest supersymmetric particle is often the neutralino, motivating dark matter analyses related to observations from Planck, WMAP, and direct detection experiments such as XENON, LUX, and PandaX. Indirect signatures include contributions to anomalous magnetic moment measurements performed at Brookhaven National Laboratory and Fermilab, and to flavor observables measured by BaBar and Belle II collaborations.

Experimental Constraints and Limits

Collider searches at LEP set early bounds on chargino and slepton masses, while analyses from Tevatron experiments CDF and D0 tightened constraints on squarks and gluinos. The LHC experiments ATLAS and CMS provided the most stringent limits through multijet plus missing energy and multilepton searches, with global fits appearing in reports from groups at CERN, DESY, and IPPP. Precision electroweak tests and Higgs boson mass measurements by ATLAS and CMS constrain stop sector parameters, and flavor physics results from LHCb and Belle II restrict regions with large tan(beta). Dark matter relic density extracted from Planck and WMAP and null results from XENON, LUX, and PandaX experiments further reduce viable parameter space, as summarized in review articles in journals associated with APS and IOP Publishing.

Variants and Extensions

Variants relax one or more universality assumptions, connecting to models developed by groups at Stanford University, University of Cambridge, and Yale University. Examples include non-universal Higgs mass models explored in collaborations involving Kavli Institute researchers, gauge-mediated and anomaly-mediated hybrids studied by teams at Perimeter Institute and IPMU, and string-motivated constructions linked to work at Institute for Advanced Study and Caltech. Extensions incorporate right-handed neutrinos as in seesaw mechanism implementations tied to CERN and KEK studies, or embed mSUGRA-like boundary conditions into SO(10 grand unified scenarios advanced by authors at University of Chicago and Oxford University.

Computational Tools and Parameter Scans

Parameter exploration and spectrum calculation rely on public codes developed and maintained by collaborations across institutions such as SLAC, DESY, CERN, and KIT. Common tools include spectrum generators and scanners used by analysts associated with MadGraph and PYTHIA communities, global fit frameworks from groups linked to GAMBIT and MasterCode, and dark matter interfaces used by teams at MICROMEGAS and DarkSUSY projects. Large-scale scans utilize computing resources at centers like CERN computing grid, NERSC, and national supercomputing facilities at Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory, with results reported in conference proceedings at Moriond and ICHEP and in journals affiliated with APS and IOP Publishing.

Category:Supersymmetry models