We employ the ATLAS search results for events containing jets and large missing transverse momentum, corresponding to an integrated luminosity of 1 fb −1 , to investigate the constrained minimal supersymmetric model (CMSSM) with b − τ Yukawa coupling unification. In this scenario, one of the stops is the next-to-lightest supersymmetric particle (NLSP), which co-annihilates with the lightest (LSP) neutralino to yield the desired dark matter relic abundance. The NLSP stop, here taken to be lighter than the top quark, is slightly ( < ∼ 20% − 30%) heavier than the LSP neutralino, and it primarily decays into the LSP and a charm quark. We find that the multi-jets and monojet ATLAS searches are sensitive to this scenario if the stop pair production is accompanied by a hard QCD jet. The excluded limit for the NLSP stop mass from the ATLAS data can reach 160 GeV in the coannihilation region, with mass below 140 GeV essentially excluded. A significant region of the parameter space corresponding to large m 0 values, 8 TeV < ∼ m 0 < ∼ 16 TeV, is excluded by our analysis. For LSP neutralino mass ∼ 100 GeV, the LHC constraints in some cases on the spin-dependent (spin-independent) neutralino-nucleon cross section are significantly more stringent than the current and expected bounds from Xenon, CDMS and IceCube.
We revisit a class of supersymmetric SO(10) models with t-b-τ Yukawa coupling unification condition, with emphasis on the prediction of the Higgs mass. We discuss qualitative features in this model that lead to a Higgs mass prediction close to 125 GeV. We show this with two distinct computing packages, Isajet and SuSpect, and also show that they yield similar global features in the parameter space of this model. We find that t-b-τ Yukawa coupling unification prefers values of the CP-odd Higgs mass m A to be around 600 GeV, with all colored sparticle masses above 3 TeV. We also briefly discuss prospects for testing this scenario with the ongoing and planned direct dark matter detection experiments. In this class of models with t-b-τ Yukawa unification, the neutralino dark matter particle is heavy (mχ0 1 400 GeV), which coannihilates with a stau to yield the correct relic abundance.
We propose a first order equation from which the Schrodinger equation can be derived. Matrices that obey certain properties are introduced for this purpose. We start by constructing the solutions of this equation in 1D and solve the problem of electron scattering from a step potential. We show that the sum of the spin up and down, reflection and transmission coefficients, is equal to the quantum mechanical results for this problem. Furthermore, we present a 3D version of the equation which can be used to derive the Schrodinger equation in 3D.Comment: 13 pages, 4 Figures, version to be published in FOO
We study the neutralinos and sleptons in multi-lepton final states at the LHC in light of (g − 2) µ anomaly. We scan the MSSM parameters relevant to (g − 2) µ and focus on three distinct cases with different neutralino compositions. The explanation of (g − 2) µ excess at 2σ range requires the smuon (μ 1 ) to be lighter than ∼ 500 (1000) GeV for tan β = 10 (50). Correspondingly the two lightest neutralinos,χ 0 1 ,χ 0 2 , have to be lighter than ∼ 300 (650) GeV and 900 (1500) GeV respectively. We explore the prospects of searching these light neutralinos and smuons at the LHC. The upcoming run of the LHC will be able to set 95% CL exclusion limit on Mχ0 2 (∼ 650 − 1300 GeV) and ml (∼ 670 − 775 GeV) with Mχ0
Rashba spin orbit interaction is a well studied effect in condensed matter physics and has important applications in spintronics. The Standard Model Extension (SME) includes a CPT-even term with the coefficient H µν which leads to the Rashba interaction term. From the limit available on the coefficient H µν in the SME we derive a limit on the Rashba coupling constant for Lorentz violation. In condensed matter physics the Rashba term is understood as resulting from an asymmetry in the confining potential at the interface of two different types of semiconductors. Based on this interpretation we suggest that a possible way of inducing the H µν term in the SME is with an asymmetry in the potential that confines us to 3 spatial dimensions.
We study the implications of light third generation sparticles on the production cross section and decay widths of a light CP-even Higgs boson. For simplicity, we consider scenarios in which only one of the sfermions from the third generation is light. For each case, we attempt to explain the apparently large enhancement in the Higgs production and decay in the diphoton channel with small deviations in the ZZ channel. In the MSSM framework we find that only a light stau can explain these observations while keeping the lightest CP-even Higgs boson mass in the interval 123 GeV m h 127 GeV. For the light stop scenario, the observations related to the diphoton and ZZ channel can be accommodated but, in order to satisfy the Higgs mass bound, one needs to go beyond the MSSM. In particular, we invoke vector like particles with masses around a TeV. These new particles preserve gauge coupling unification and provide additional contributions to the Higgs mass. With these new contributions a 126 GeV Higgs mass is easily achieved. We also find that with only a light sbottom quark, the above mentioned excess is hard to accommodate.
We consider two distinct classes of Yukawa unified supersymmetric SO(10) models with non-universal and universal soft supersymmetry breaking (SSB) gaugino masses at M GUT . In both cases, we assume that the third family SSB sfermion masses at M GUT are different from the corresponding sfermion masses of the first two families (which are equal). For the SO(10) model with essentially arbitrary (non-universal) gaugino masses at M GUT , it is shown that t-b-τ Yukawa coupling unification is compatible, among other things, with the 125 GeV Higgs boson mass, the WMAP relic dark matter density, and with the resolution of the apparent muon g − 2 anomaly. The colored sparticles in this case all turn out to be quite heavy, of order 5 TeV or more, but the sleptons (smuon and stau) can be very light, of order 200 GeV or so. For the SO(10) model with universal gaugino masses and NUHM2 boundary conditions, the muon g − 2 anomaly cannot be resolved. However, the gluino in this class of models is not too heavy, 3 TeV, and therefore may be found at the LHC.
We explore extensions of the MSSM in which TeV scale vector-like multiplets can mediate observable n − n oscillations, without causing conflict with the proton decay experiments, with a U(1) symmetry playing an important role. The colored vector-like particles, in particular, may be found at the LHC through some decay modes arising from their direct couplings to quarks.Low energy supersymmetry (SUSY) provides one of the most compelling extensions of the standard model (SM). In particular, the minimal supersymmetric standard model (MSSM) with unbroken 'matter' parity offers an attractive resolution of the gauge hierarchy problem, delivers a compelling cold dark matter candidate, and nicely implements gauge coupling unification. It also predicts that the lightest CP-even Higgs mass, assuming TeV scale soft SUSY breaking parameters, cannot be much heavier than about 130 GeV. It is gratifying to note that the MSSM predictions will be tested at the soon to be launched Large Hadron Collider (LHC).Possible extensions of the MSSM have been frequently discussed in the literature. In a recent paper [1] it was shown that by adding new TeV scale vector-like particles, it is possible to increase the upper bound on the mass of the lightest CP-even Higgs boson to 160 GeV, provided there exists a direct coupling between the new vector-like particles and the MSSM Higgs fields. To retain gauge coupling unification it is helpful that the new particles comprise the same particle content as the complete SU(5) multiplets such as 5 + 5 and 10 + 10.Since LHC is a hadron collider, it is expected that the colored components of these vectorlike fields can be produced there. In general, these colored particles will couple to quarks and leptons, which makes the discussion of the creation and decay modes of the vector-like matter quite interesting [2]. In addition to the direct creation of the new particles in LHC, the new couplings with the new colored particles can generate, as we will see, exotic phenomena related to baryon number violation. Indeed, it has been noted in the past that n − n oscillations [3,4,5,6,7,8,9,10,11] can be experimentally accessible if there exist TeV scale colored particles with appropriate baryon number violating couplings to the known particles [8]. Baryon number B is conserved to all orders in perturbation theory in the standard model, up to Planck scale suppressed operators. On the other hand, a naive SUSY extension of the SM leads to rapid nucleon decay via renormalizable couplings. This disaster is usually prevented by introducing a discrete Z 2 'matter' (or R) parity. This version of the MSSM with unbroken matter parity allows nucleon decay to proceed via Planck scale suppressed dimensionfive operators. With the current proton lifetime limit τ p 5 × 10 33 yrs., this implies that the dimensionless coefficients accompanying these operators must be tiny, of order 10 −7 or less. The coefficients can usually be arranged to be tiny by a flavor structure similar to the small Yukawa couplings for the first generatio...
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