Supersymmetry-breaking Scalar Masses Research Articles

Candidate phases for SU(2) adjoint QCD$_4$ with two flavors from $\mathcal{N}=2$ supersymmetric Yang-Mills theory

We study four-dimensional adjoint QCD with gauge group SU(2)SU(2) and two Weyl fermion flavors, which has an SU(2)_RSU(2)R chiral symmetry. The infrared behavior of this theory is not firmly established. We explore candidate infrared phases by embedding adjoint QCD into {\mathcal N}=2𝒩=2 supersymmetric Yang-Mills theory deformed by a supersymmetry-breaking scalar mass MM that preserves all global symmetries and ’t Hooft anomalies. This includes ’t Hooft anomalies that are only visible when the theory is placed on manifolds that do not admit a spin structure. The consistency of this procedure is guaranteed by a nonabelian spin-charge relation involving the SU(2)_RSU(2)R symmetry that is familiar from topologically twisted {\mathcal N}=2𝒩=2 theories. Since every vacuum on the Coulomb branch of the {\mathcal N}=2𝒩=2 theory necessarily matches all ’t Hooft anomalies, we can generate candidate phases for adjoint QCD by deforming the theories in these vacua while preserving all symmetries and ’t Hooft anomalies. One such deformation is the supersymmetry-breaking scalar mass MM itself, which can be reliably analyzed when MM is small. In this regime it gives rise to an exotic Coulomb phase without chiral symmetry breaking. By contrast, the theory near the monopole and dyon points can be deformed to realize a candidate phase with monopole-induced confinement and chiral symmetry breaking. The low-energy theory consists of two copies of a \mathbb{CP}^1ℂℙ1 sigma model, which we analyze in detail. Certain topological couplings that are likely to be present in this \mathbb{CP}^1ℂℙ1 model turn the confining solitonic string of the model into a topological insulator. We also examine the behavior of various candidate phases under fermion mass deformations. We speculate on the possible large-MM behavior of the deformed {\mathcal N}=2𝒩=2 theory and conjecture that the \mathbb{CP}^1ℂℙ1 phase eventually becomes dominant.

Muon mathbf {g-2}, neutralino dark matter and stau NLSP

We explore the implications of resolving the muon g-2 anomaly in a SU(4)_c times SU(2)_L times SU(2)_R model, where the soft supersymmetry breaking scalar and gaugino masses break the left-right (LR) symmetry. A 2sigma resolution of the anomaly requires relatively light sleptons, chargino and LSP neutralino. The stau turns out to be the NLSP of mass m_{tilde{tau }}lesssim 400 GeV, and the sleptons from the first two families can be as heavy as about 800 GeV. The chargino is also required to be lighter than about 600 GeV to accommodate the muon g-2 solutions consistent with the dark matter relic density constraint. The dominant right-handed nature of the light slepton states suppress the sensitivity of possible signals which can be probed in Run3 experiments at the LHC. We also discuss the impact of accommodating the Higgs boson mass and the vacuum stability of the scalar potential for these solutions. Although a light stau can be compatible with the stability of the scalar potential, the Higgs boson mass constraint has a strong impact on the solutions with tan beta bounded from above, namely tan beta lesssim 20. The Higgsinos are heavier than about 4 TeV, and the LSP neutralino has the correct relic density if it is Bino-like. We identify stau–neutralino coannihilation as the dominant mechanism for realizing the desired dark matter relic density, with sneutrino–neutralino coannihiliation playing a minor role. These bino-like dark matter solutions can yield a spin-independent scattering cross-section on the order of 10^{-13}pb which hopefully, can be expected to be tested in the near future.

Likelihood analysis of the sub-GUT MSSM in light of LHC 13-TeV data

We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale M_mathrm{in} below the supersymmetric grand unification scale M_mathrm{GUT}, as can occur in mirage mediation and other models. In addition to M_mathrm{in}, such ‘sub-GUT’ models have the 4 parameters of the CMSSM, namely a common gaugino mass m_{1/2}, a common soft supersymmetry-breaking scalar mass m_0, a common trilinear mixing parameter A and the ratio of MSSM Higgs vevs tan beta , assuming that the Higgs mixing parameter mu > 0. We take into account constraints on strongly- and electroweakly-interacting sparticles from sim 36/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for M_mathrm{in}sim 10^5 to 10^9 ,, mathrm {GeV}, with M_mathrm{in}sim M_mathrm{GUT} disfavoured by Delta chi ^2 sim 3 due to the mathrm{BR}(B_{s, d} rightarrow mu ^+mu ^-) constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with m_{tilde{chi }^0_{1}} sim 1 ,, mathrm {TeV}, with annihilation via heavy Higgs bosons H / A and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the (g-2)_mu constraint, finding similar results whether or not it is included.

Maximal sfermion flavour violation in super-GUTs.

We consider supersymmetric grand unified theories with soft supersymmetry-breaking scalar masses m_0 specified above the GUT scale (super-GUTs) and patterns of Yukawa couplings motivated by upper limits on flavour-changing interactions beyond the Standard Model. If the scalar masses are smaller than the gaugino masses m_{1/2}, as is expected in no-scale models, the dominant effects of renormalisation between the input scale and the GUT scale are generally expected to be those due to the gauge couplings, which are proportional to m_{1/2} and generation independent. In this case, the input scalar masses m_0 may violate flavour maximally, a scenario we call MaxSFV, and there is no supersymmetric flavour problem. We illustrate this possibility within various specific super-GUT scenarios that are deformations of no-scale gravity.

Supersymmetry searches in GUT models with non-universal scalar masses

We study SO(10), SU(5) and flipped SU(5) GUT models with non-universal soft supersymmetry-breaking scalar masses, exploring how they are constrained by LHC supersymmetry searches and cold dark matter experiments, and how they can be probed and distinguished in future experiments. We find characteristic differences between the various GUT scenarios, particularly in the coannihilation region, which is very sensitive to changes of parameters. For example, the flipped SU(5) GUT predicts the possibility of ̃t1−χ coannihilation, which is absent in the regions of the SO(10) and SU(5) GUT parameter spaces that we study. We use the relic density predictions in different models to determine upper bounds for the neutralino masses, and we find large differences between different GUT models in the sparticle spectra for the same LSP mass, leading to direct connections of distinctive possible experimental measurements with the structure of the GUT group. We find that future LHC searches for generic missing ET, charginos and stops will be able to constrain the different GUT models in complementary ways, as will the Xenon 1 ton and Darwin dark matter scattering experiments and future FERMI or CTA γ-ray searches.

Indirect dark matter search with the ANTARES neutrino telescope

Using the ANTARES neutrino telescope, the largest neutrino telescope in the Northern hemisphere, from its first configuration with 5 lines of photodetectors to the actual nominal one corresponding to a total of 12 lines, we have studied our ability to search indirectly an evidence of Dark Matter annihilations in heavy astrophysical objects as the Sun. First limits have been obtained using the data recorded by ANTARES in 2007 and 2008, and compared with neutrino fluxes predicted within a minimal supersymmetric extension of the Standard Model with supersymmetry-breaking scalar and gaugino masses constrained to be universal at the GUT scale, the CMSSM, as well as a minimal Universal Extra-Dimensions scenario with one extra compact dimension where all the Standard Model fields propagate into the bulk, the mUED. The current limits over the neutrino/muon fluxes coming from the dark matter self-annihilations, as well as the spin-dependent and spin-independent cross-sections, are presented.

Light stops from Seiberg duality

If low-energy supersymmetry is realized in nature, a seemingly contrived hierarchy in the squark mass spectrum appears to be required. We show that composite supersymmetric theories at the bottom of the conformal window can automatically yield the spectrum that is suggested by experimental data and naturalness. With a non-tuned choice of parameters, the only superpartners below one TeV will be the partners of the Higgs, the electroweak gauge bosons, the left-handed top and bottom, and the right-handed top, which are precisely the particles needed to make weak scale supersymmetry breaking natural. In the model considered here, these correspond to composite (or partially composite) degrees of freedom via Seiberg duality, while the other MSSM fields, with their heavier superpartners, are elementary. The key observation is that at or near the edge of the conformal window, soft supersymmetry breaking scalar and gaugino masses are transmitted only to fundamental particles at leading order. With the potential that arises from the duality, a Higgs with a 125 GeV mass, with nearly SM production rates, is naturally accommodated without tuning. The lightest ordinary superpartner is either the lightest stop or the lightest neutralino. If it is the stop, it is natural for it to be almost degenerate with the top, in which case it decays to top by emitting a very soft gravitino, making it quite difficult to find this mode at the LHC and more challenging to find SUSY in general, yielding a simple realization of the stealth supersymmetry idea. We analyze four benchmark spectra in detail.

Supersymmetry breaking scalar masses and trilinear soft terms from high-dimensional operators in [formula omitted] SUSY GUT

In the GmSUGRA scenario with the higher-dimensional operators containing the GUT Higgs fields, we systematically studied the supersymmetry breaking scalar masses, SM fermion Yukawa coupling terms, and trilinear soft terms in the E 6 SUSY GUT model where the gauge symmetry is broken down to the SO ( 10 ) × U ( 1 ) gauge symmetry, SU ( 3 ) C × SU ( 3 ) L × SU ( 3 ) R gauge symmetry, SU ( 6 ) × SU ( 2 ) a ( a = L , R , X ) gauge symmetry, flipped SU ( 5 ) gauge symmetry etc. In addition, we considered the scalar and gaugino mass relations, which can be preserved from the GUT scale to the electroweak scale under one-loop RGE running, in the SU ( 3 ) C × SU ( 3 ) L × SU ( 3 ) R model arising from the E 6 model. With such relations, we may distinguish the mSUGRA and GmSUGRA scenarios if we can measure the supersymmetric particle spectrum at the LHC and ILC.

Supersymmetry breaking scalar masses and trilinear soft terms in generalized minimal supergravity

In the generalized minimal supergravity (GmSUGRA) scenario, we systematically study the supersymmetry breaking scalar masses, Standard Model fermion Yukawa coupling terms, and trilinear soft terms in SU(5) models with the Higgs fields in the 24 and 75 representations, and in SO(10) models where the gauge symmetry is broken down to the Pati-Salam SU(4) C × SU(2) L × SU(2) R gauge symmetry, SU(3) C × SU(2) L × SU(2) R ×U(1)B−L gauge symmetry, George-Glashow SU(5)×U(1)′ gauge symmetry, flipped SU(5) × U(1) X gauge symmetry, and SU(3) C × SU(2) L × U(1)1 × U(1)2 gauge symmetry. Most importantly, we for the first time consider the scalar and gaugino mass relations, which can be preserved from the unification scale to the electroweak scale under one-loop renormalization group equation running, in the SU(5) models, the Pati-Salam models and flipped SU(5)×U(1) X models arising from SO(10) models. With such interesting relations, we may distinguish the minimal supergravity (mSUGRA) and GmSUGRA scenarios if the supersymmetric particle spectrum can be measured at the LHC and ILC. Thus, it provides us with another important window of opportunity at the Planck scale.

Neutrino fluxes from constrained minimal supersymmetric standard model lightest supersymmetric particle annihilations in the Sun

We evaluate the neutrino fluxes to be expected from neutralino LSP annihilations inside the Sun, within the minimal supersymmetric extension of the Standard Model with supersymmetry-breaking scalar and gaugino masses constrained to be universal at the GUT scale (the CMSSM). We find that there are large regions of typical CMSSM $(m_{1/2}, m_0)$ planes where the LSP density inside the Sun is not in equilibrium, so that the annihilation rate may be far below the capture rate. We show that neutrino fluxes are dependent on the solar model at the 20% level, and adopt the AGSS09 model of Serenelli et al. for our detailed studies. We find that there are large regions of the CMSSM $(m_{1/2}, m_0)$ planes where the capture rate is not dominated by spin-dependent LSP-proton scattering, e.g., at large $m_{1/2}$ along the CMSSM coannihilation strip. We calculate neutrino fluxes above various threshold energies for points along the coannihilation/rapid-annihilation and focus-point strips where the CMSSM yields the correct cosmological relic density for tan(beta) = 10 and 55 for $\mu$ > 0, exploring their sensitivities to uncertainties in the spin-dependent and -independent scattering matrix elements. We also present detailed neutrino spectra for four benchmark models that illustrate generic possibilities within the CMSSM. Scanning the cosmologically-favored parts of the parameter space of the CMSSM, we find that the IceCube/DeepCore detector can probe at best only parts of this parameter space, notably the focus-point region and possibly also at the low-mass tip of the coannihilation strip.

Some physics of the two-dimensional [formula omitted] supersymmetric Yang–Mills theory: Lattice Monte Carlo study

We illustrate some physical application of a lattice formulation of the two-dimensional N=(2,2) supersymmetric SU(2) Yang–Mills theory with a (small) supersymmetry breaking scalar mass. Two aspects, power-like behavior of certain correlation functions (which implies the absence of the mass gap) and the static potential V(R) between probe charges in the fundamental representation, are considered. For the latter, for R≲1/g, we observe a linear confining potential with a finite string tension. This confining behavior appears distinct from a theoretical conjecture that a probe charge in the fundamental representation is screened in two-dimensional gauge theory with an adjoint massless fermion, although the static potential for R≳1/g has to be systematically explored to conclude real asymptotic behavior in large distance.

The Higgs intense-coupling regime in constrained SUSY models and its astrophysical implications

We analyze the Higgs intense--coupling regime, in which all Higgs particles of the Minimal Supersymmetric Standard Model are light with masses of the same order and the value of $\tb$ the ratio of vacuum expectation values of the two Higgs fields is large, in the framework of Supergravity scenarios with non--universal soft Supersymmetry breaking scalar masses in the Higgs sector. In particular, we calculate the relic density abundance of the lightest neutralino candidate for cold dark matter and the rates in direct and indirect detection at present and future experiments. We first show that while in the mSUGRA model this regime is disfavored by present data, there are regions in the parameter space of models with non--universal Higgs masses where it can occur. We then show that because of the large value of $\tan\beta$ and the relatively low values of the neutral Higgs boson masses, the cross section for neutralino--nucleon scattering is strongly enhanced in this regime and would allow for the observation of a signal in direct detection experiments such as CDMS--Soudan. The expected sensitivity of gamma--ray detectors like GLAST might be also sufficient to observe the annihilation of neutralinos in such a regime.

OnBs→μ+μ−and cold dark matter scattering in the MSSM with non-universal Higgs masses

We show that present experimental constraints on B_s -> mu+ mu- decay and the CDMS upper limit on the cold dark matter elastic scattering cross section already have significant impact on the parameter space of the minimal supersymmetric extension of the Standard Model (MSSM) with non-universal supersymmetry-breaking scalar masses for the Higgs multiplets (NUHM). The relaxation of scalar universality in the MSSM allows the possibility of a relatively light mass M_A for the pseudoscalar Higgs boson. The present upper limit on B_s -> mu+ mu- already excludes much of the scope for this possibility in the NUHM, in contrast to the constrained MSSM with universal scalar masses (CMSSM), where B_s -> mu+ mu- decay does not exclude any ranges of parameters not already excluded by b -> s \gamma decay. Cold dark matter scattering is also enhanced for small M_A, but the impact of present upper limit on B_s -> mu+ mu- on the NUHM parameter space is in many cases greater than that of the CDMS scattering limit, particularly at large tanb.

PROBING SO(10) SYMMETRY BREAKING PATTERNS THROUGH SFERMION MASS RELATIONS

We consider supersymmetric SO(10) grand unification where the unified gauge group can break to the Standard Model gauge group through different chains. The breaking of SO(10) necessarily involves the reduction of the rank, and consequent generation of nonuniversal supersymmetry breaking scalar mass terms. We derive squark and slepton mass relations, taking into account these nonuniversal contributions to the sfermion masses, which can help distinguish between the different chains through which the SO(10) gauge group breaks to the Standard Model gauge group. We then study some implications of these nonuniversal supersymmetry breaking scalar masses for the low energy phenomenology.

Updated post-WMAP benchmarks for supersymmetry

We update a previously-proposed set of supersymmetric benchmark scenarios, taking into account the precise constraints on the cold dark matter density obtained by combining WMAP and other cosmological data, as well as the LEP and b -> s gamma constraints. We assume that R parity is conserved and work within the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking scalar and gaugino masses m_0 and m_1/2. In most cases, the relic density calculated for the previous benchmarks may be brought within the WMAP range by reducing slightly m_0, but in two cases more substantial changes in m_0 and m_1/2 are made. Since the WMAP constraint reduces the effective dimensionality of the CMSSM parameter space, one may study phenomenology along `WMAP lines' in the (m_1/2, m_0) plane that have acceptable amounts of dark matter. We discuss the production, decays and detectability of sparticles along these lines, at the LHC and at linear e+ e- colliders in the sub- and multi-TeV ranges, stressing the complementarity of hadron and lepton colliders, and with particular emphasis on the neutralino sector. Finally, we preview the accuracy with which one might be able to predict the density of supersymmetric cold dark matter using collider measurements.

SQUARK AND SLEPTON MASSES AS PROBES OF SUPERSYMMETRIC SO(10) UNIFICATION

We carry out an analysis of the non-universal supersymmetry breaking scalar masses arising in SO(10) supersymmetric unification. By considering patterns of squark and slepton masses, we derive a set of sum rules for the sfermion masses which are independent of the manner in which SO(10) breaks to the Standard Model gauge group via its SU(5) subgroups. The phenomenology arising from such non-universality is unaffected by the symmetry breaking pattern, so long as the breaking occurs via any of the SU(5) subgroups of the SO(10) group.

Lower limits on soft supersymmetry-breaking scalar masses

Working in the context of the CMSSM, we argue that phenomenological constraints now require the universal soft supersymmetry-breaking scalar mass m 0 be non-zero at the input GUT scale. This conclusion is primarily imposed by the LEP lower limit on the Higgs mass and the requirement that the lightest supersymmetric particle not be charged. We find that m 0 >0 for all tan β if μ <0, and m 0 =0 may be allowed for μ >0 only when tan β ∼8 and one allows an uncertainty of 3+ GeV in the theoretical calculation of the Higgs mass. Upper limits on flavour-changing neutral interactions in the MSSM squark sector allow substantial violations of non-universality in the m 0 values, even if their magnitudes are comparable to the lower limit we find in the CMSSM. Also, we show that our lower limit on m 0 at the GUT scale in the CMSSM is compatible with the no-scale boundary condition m 0 =0 at the Planck scale.

Exploration of elastic scattering rates for supersymmetric dark matter

We explore the possible cross sections for the elastic scattering of neutralinos $\ensuremath{\chi}$ on nucleons $p,n$ in the minimal supersymmetric extension of the standard model (MSSM). Universality of the soft supersymmetry-breaking scalar masses for the Higgs multiplets is not assumed, but the MSSM parameters are nevertheless required to lead consistently to an electroweak vacuum. We explore systematically the region of MSSM parameter space where CERN LEP and other accelerator constraints are respected, and the relic neutralino density lies in the range $0.1&lt;~{\ensuremath{\Omega}}_{\ensuremath{\chi}}{h}^{2}&lt;~0.3$ preferred by cosmology. We also discuss models with ${\ensuremath{\Omega}}_{\ensuremath{\chi}}{h}^{2}&lt;0.1,$ in which case we scale the density of supersymmetric dark matter in our galactic halo by ${\ensuremath{\Omega}}_{\ensuremath{\chi}}{h}^{2}/0.1,$ allowing for the possible existence of some complementary form of cold dark matter. We restrict our attention to $\mathrm{tan}\ensuremath{\beta}&lt;~10,$ for which reliable relic-density calculations are available. Within this range of $\mathrm{tan}\ensuremath{\beta},$ we find values of the cross sections that are considerably lower than the present experimental sensitivities. At low neutralino masses, ${m}_{\ensuremath{\chi}}\ensuremath{\lesssim}100$ GeV, the cross sections may be somewhat higher than in the constrained MSSM with universal soft Higgs boson masses, though they are generally lower. In the case of large ${m}_{\ensuremath{\chi}},$ the cross sections we find may be considerably larger than in the constrained model, but still well below the present experimental sensitivity.

Supersymmetric dark matter in the light of CERN LEP and the Fermilab Tevatron collider

We analyze the accelerator constraints on the parameter space of the Minimal Supersymmetric extension of the Standard Model, comparing those now available from LEP II and anticipating the likely sensitivity of Tevatron Run II. The most important limits are those from searches for charginos, neutralinos and Higgs bosons at LEP, and searches for stop squarks, charginos and neutralinos at the Tevatron Collider. We also incorporate the constraints derived from b --> s + gamma decay, and discuss the relevance of charge- and colour-breaking minima in the effective potential. We combine and compare the different constraints on the Higgs-mixing parameter mu, the gaugino-mass parameter m_{1/2} and the scalar-mass parameter m0, incorporating radiative corrections to the physical particle masses. We focus on the resulting limitations on supersymmetric dark matter, assumed to be the lightest neutralino, incorporating coannihilation effects in the calculation of the relic abundance. We find that m_chi > 51 GeV and tan(beta) > 2.2 if all soft supersymmetry-breaking scalar masses are universal, including those of the Higgs bosons, and that these limits weaken to m_chi > 46 GeV and tan(beta) > 1.9 if non-universal scalar masses are allowed. Light neutralino dark matter cannot be primarily Higgsino in composition.

Dynamical supersymmetry breaking in models with a Green–Schwarz mechanism

We consider supersymmetry breaking in theories with gaugino condensation in the presence of an anomalous U(1) symmetry with anomaly cancellation by the Green-Schwarz mechanism. In these models, a Fayet-Iliopoulos D-term can give important contributions to the soft supersymmetry-breaking scalar masses. Most discussions of this possibility have ignored the dilaton field. We argue that this is not appropriate in general, and show that the F-term contributions to the soft breaking terms are comparable to or much larger than the D-term contributions, depending on how the dilaton is stabilized. We discuss phenomenological implications of these results.