A. F. Kord, S. Hosseini
We present the two-loop $β$-functions for non-standard soft supersymmetry-breaking couplings including non-standard R-parity violating soft terms in the Minimal Supersymmetric Standard Model
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We consider the renormalisation of the Fayet-Iliopoulos D-term in a softly-broken supersymmetric gauge theory with a non-simple gauge group containing an abelian factor, and present the associated beta-function through three loops. We also include in an appendix the result for several abelian factors. We specialise to the case of the minimal supersymmetric standard model (MSSM), and investigate the behaviour of the Fayet-Iliopoulos coupling for various boundary conditions at the unification scale. We focus particularly on the case of non-standard soft supersymmetry breaking couplings, for whic…
We calculate chargino production at a future linear collider, including full one-loop contributions in the MSSM with complex parameters. To achieve this, we require a comprehensive approach to renormalisation in the chargino and neutralino sector, for the case where parameters can be complex. Using the field renormalisation as developed in Refs. [1-3], we investigate the parameter renormalisation in the complex case. We also study the numerical role of the choice of renormalisation scheme as in Refs. [2-3]. Finally we present new results showing the effect of the phases on the resulting cross …
We extend the formalism developed in Ref. [20] for the renormalisation of the chargino-neutralino sector to the most general case of the MSSM with complex parameters. We show that products of imaginary parts arising from MSSM parameters and from absorptive parts of loop integrals can already contribute to predictions for physical observables at the one-loop level, and demonstrate that the consistent treatment of such contributions gives rise to non-trivial structure, either in the field renormalisation constants or the corrections associated with the external legs of the considered diagrams. W…
We evaluate O(alpha_b alpha_s) corrections in the Higgs boson sector of the CP-conserving MSSM, generalising the known result in the literature to arbitrary values of tan beta. A detailed analysis of the renormalisation in the bottom/scalar bottom sector is performed. Concerning the lightest MSSM Higgs boson mass, we find relatively small corrections for positive mu, while for mu < 0 the genuine two-loop O(alpha_b alpha_s) corrections can amount up to 3 GeV. Different renormalisation schemes are applied and numerically compared. It is demonstrated that some care has to be taken in choosing an …
An on-shell renormalisation programme for the chargino/neutralino and the sfermion sectors within the Minimal Supersymmetric Standard Model as implemented in a fully automated code, SloopS, for the calculation of one-loop processes at the colliders and in astrophysics, is presented. This is a sequel to our study in arXiv:0807.4668 [hep-ph] where an on-shell renormalisation of the Higgs (and the gauge/fermion) sector is performed. The issue of mixing is treated in a unified and coherent manner in all these sectors, in particular we give some new insight into the renormalisation of the mixing an…
Renormalisation Group Equation(RGE) for color and top couplings sector of MSSM has been solved. The mass of the top comes out to be 180.363$\pm$ 10.876 GeV and $β_{top}$=$\fracπ{2}$. It is conjectured that the masses of the other 11 fermions and the CKM phase angle $ϕ$ can be theoretically estimated. The results confirm the fact that the quarks and leptons have been created having equal mass $\sim$ 115 GeV at the MSSM GUT scale $\sim ~2.2\times 10^{16}$ GeV.
Preliminary Remarks. Gauge mediated supersymmetry breaking. Gravity mediated supersymmetry breaking. Anomaly mediated supersymmetry breaking. Gaugino mediated supersymmetry breaking. Braneworld supersymmetry breaking. Conclusions.
We show that a particular ``universal'' form for the soft-breaking couplings in a softly broken $N=1$ supersymmetric gauge theory is renormalisation-group invariant through two loops, provided we impose one simple condition on the dimensionless couplings. The universal form for the trilinear couplings and mass terms is identical to that found in popular derivations of the soft-breaking terms from strings or supergravity.
Complete electroweak O(Nc^2) two-loop contributions to the Higgs boson masses in the MSSM and aspects of two-loop renormalisation
本文计算了MSSM中希格斯玻色子质量的完整电弱O(Nc^2)双圈贡献，分析了tanb重整化方案间的关系，并证明新贡献虽小于已知双圈修正但大于实验不确定度，具有重要物理意义。
We present full renormalisation group equations for the MSSM with R-parity violation, including all soft supersymmetry breaking terms. The inclusion of dimensionless R-parity violating couplings can generate many possible low energy effects through the generation of off-diagonal soft masses violating lepton and quark flavour, and through the generation of lepton-Higgs mixing. We discuss the relation between the weak and unification scale R-parity violation and study the effects on neutrino mass generation and $μ\to eγ$.
We give an extensive description of the renormalisation of the Higgs sector of the minimal supersymmetric model in SloopS. SloopS is an automatised code for the computation of one-loop processes in the MSSM. In this paper, the first in a series, we study in detail the non gauge invariance of some definitions of tan(beta). We rely on a general non-linear gauge fixing constraint to make the gauge parameter dependence of different schemes for tan(beta) at one-loop explicit. In so doing, we update, within these general gauges, an important Ward-Slavnov-Taylor identity on the mixing between the pse…
If supersymmetric particles are discovered, an important problem will be to determine how supersymmetry has been broken. At collider energies, supersymmetry breaking can be parameterised by soft supersymmetry breaking parameters. Several mechanisms for supersymmetry breaking have been proposed, which are all characterised by patterns in the high scale values of these parameters. Therefore, looking for such patterns will give us important clues about the way supersymmetry has been broken in Nature. In this master thesis, we study an approach to find these patterns using Renormalisation Group in…
Two-loop renormalisation and Higgs phenomenology in the five-dimensional MSSM
本研究对五维最小超对称标准模型开展双圈分析，推导相关重整化群方程，证实其紫外行为良好，计算含KK重求和的希格斯有效势，经数值研究确立紧致化尺度等参数约束，得到与实验一致的可行参数空间。
The infra-red fixed points are determined for all the parameters of the MSSM. They dominate the renormalisation group running when the top-Yukawa is in the quasi-fixed point regime (i.e. large at the GUT scale). We examine this behaviour analytically, by solving the full set of one-loop renormalisation group equations in the approximation that the electroweak contributions are negligible, and also numerically. We find the quasi-fixed points for the top-quark trilinear couplings; A_{U_{α3}} = A_{U_{3α}}=-0.59 m_g independently of the input parameters at the unification scale. All the remaining …
In the MSSM the quasi-infra-red fixed point for the top-quark Yukawa coupling gives rise to specific predictions for the soft-breaking parameters. We discuss the extent to which these predictions are modified by the introduction of additional ``non-holomorphic'' soft-breaking terms. We also show that in a specific class of theories there exists an RG-invariant trajectory for the ``non-holomorphic'' terms, which can be understood using a holomorphic spurion term.
Supersymmetric models with broken R-parity provide mechanisms that allow to generate Majorana neutrino masses and magnetic moments through virtual particle-sparticle loops. This constitutes an attractive alternative to the see-saw mechanism. In this paper we present a detailed calculation of the transition magnetic moments of a Majorana neutrino in gauge mediated supersymmetry breaking MSSM without R-parity. We base our analysis on the renormalization group evolution of the MSSM parameters, which are unified at the GUT scale.
The R-parity non-conservation phenomenology within the minimal supersymmetric standard model with gauge mediated supersymmetry breaking has been studied. New constraints on the lepton number violating constant $λ_{111}^\prime$ were imposed by non-observability of the neutrinoless double beta decay. We find that $λ_{111}^\prime$ depends strongly on the effective supersymmetry breaking scale $Λ$ only and deduce limits which are much stronger than those previously found in literature.
A method is described to probe high-scale physics in lower-energy experiments by employing sum rules in terms of renormalisation group invariants. The method is worked out in detail for the study of supersymmetry-breaking mechanisms in the context of the Minimal Supersymmetric Standard Model. To this end sum rules are constructed that test either specific models of supersymmetry breaking or general properties of the physics that underlies supersymmetry breaking, such as unifications and flavour-universality.
We compare theoretical and experimental predictions of two main classes of models addressing fermion mass hierarchies and flavour changing neutral currents (FCNC) effects in supersymmetry: Froggatt-Nielsen (FN) U(1) gauged flavour models and Nelson-Strassler/extra dimensional models with hierarchical wave functions for the families. We show that whereas the two lead to identical predictions in the fermion mass matrices, the second class generates a stronger suppression of FCNC effects. We prove that, whereas at first sight the FN setup is more constrained due to anomaly cancelation conditions,…
The possibility of generating a large trilinear $A_t$ soft supersymmetry breaking coupling at low energies through renormalisation group evolution in the 5D MSSM is investigated. Using the power law running in five dimensions and a compactification scale in the 10-$10^3$ TeV range, to show that gluino mass may drive a large enough $A_t$ to reproduce the measured Higgs mass and have a light stop superpartner below $\sim 1$ TeV as preferred by the fine tuning argument for the Higgs mass.
An introduction to the minimal supersymmetric Standard Model (MSSM) is given. The motivation for ``low-energy'' supersymmetry is reviewed, and the structure of the MSSM is outlined. In its most general form, the MSSM can be viewed as a low-energy effective theory parametrized by a set of arbitrary soft-supersymmetry-breaking parameters. A variety of techniques for reducing the parameter freedom of the MSSM are surveyed. The search for supersymmetry below and above the threshold for supersymmetric particle production presents a challenging task for experimentalists at present and future collide…
A fairly elementary introduction to supersymmetric field theories in general and the minimal supersymmetric Standard Model (MSSM) in particular is given. Topics covered include the cancellation of quadratic divergencies, the construction of the supersymmetric Lagrangian using superfields, the field content of the MSSM, electroweak symmetry breaking in the MSSM, mixing between different superparticles (current eigenstates) to produce mass eigenstates, and the embedding of the MSSM in so--called minimal supergravity.
Collisions of non-topological solitons, Q-balls, are studied in a typical potential in the Minimal Supersymmetric Standard Model where supersymmetry has been broken by a gravitationally coupled hidden sector. Q-ball collisions are studied numerically on a two dimensional lattice for a range of Q-ball charges. Total cross-sections, as well as cross-sections for fusion and charge-exchange are calculated. The average percentage increase in charge carried by the largest Q-ball after a collision is found to be weakly dependent on the initial charge.
This work provides an elementary introduction to the Higgs sector renormalisation within the Minimal Suppersymmetric Standard Model (MSSM) framework. The MSSM tree-level relation $m_h^2+m_H^2=m_A^2+m_Z^2$ is renormalised using the standard technique of direct computation of the relevant one-loop Feynman diagrams. The expected cancellation of ultraviolet divergences is explicitly checked and the well-known leading-log term is recovered.
Collisions of non-topological solitons, Q-balls, are considered in the Minimal Supersymmetric Standard Model where supersymmetry has been broken at a low energy scale via a gauge mediated mechanism. Q-ball collisions are studied numerically on a two dimensional lattice for a range of Q-ball charges. Total cross-sections, as well as fusion and geometrical cross-sections are calculated. The total and geometrical cross-sections appear to converge with increasing charge. The fusion cross-section has been estimated to be larger than 60% of the geometrical cross-section for large balls.
We show the impact of the electroweak, and in one instance the QCD, one-loop corrections on the relic density of dark matter in the MSSM which is provided by the lightest neutralino. We cover here some of the most important scenarii: annihilation into fermions for a bino-like neutralino, annihilation involving gauge bosons in the case of a mixed neutralino, the neutralino-stau co-annihilation region and annihilation into a bottom quark pair. The corrections can be large and should be taken into account in view of the present and forthcoming increasing precision on the relic density measurement…
These lecture notes are from a first course on the Minimal Supersymmetric Standard Model. The level of the notes is introductory and pedagogical. Standard Model, basic supersymmetry algebra and its representations are considered as prerequisites. The topics covered include particle content, structure of the lagrangian, supersymmetry breaking soft terms, electroweak symmetry breaking and the sparticle mass spectrum. Popular supersymmetry breaking models like minimal supergravity and gauge mediation are also introduced.
The Minimal Supersymmetric Standard Model (MSSM) can include two soft breaking terms which are often neglected: a non-analytic scalar trilinear coupling and a Higgsino bilinear term. A set of high-scale boundary conditions consistent with the reparameterisation invariance which the model possesses is obtained. The three-family renormalisation group equations for the MSSM with these terms are presented. The ranges of the universal high-scale values of these couplings which lead to an acceptable TeV-scale theory are obtained, as is the supersymmetric particle spectrum at this scale. The effect o…
Excited Q-balls are studied by numerical simulations in the Minimal Supersymmetric Standard Model with supersymmetry broken by a gravity mediated mechanism. It is found that there is a suppression factor of $\cO(10^{-2})$ in the rate at which a Q-ball can emit their excess energy compared to the rate set by the dynamical scale of the field, $m$. Furthermore, it is noted that a Q-ball can withstand a large amount of excess energy without losing a significant amount of its charge. The cosmological importance of these properties are considered for Q-balls in the thermal bath of the early universe…
These lectures, presented at the 2006 TASI summer school, give a general introduction to supersymmetry, emphasizing its application to models of elementary particle physics at the 100 GeV energy scale. I discuss the following topics: the construction of supersymmetric Lagrangians with scalars, fermions, and gauge bosons, the structure and mass spectrum of the Minimal Supersymmetric Standard Model (MSSM), the measurement of the parameters of the MSSM at high-energy colliders, and the solutions that the MSSM gives to the problems of electroweak symmetry breaking and dark matter.
We present a comprehensive renormalisation group analysis of the Littlest Seesaw model involving two right-handed neutrinos and a very constrained Dirac neutrino Yukawa coupling matrix. We perform the first $χ^2$ analysis of the low energy masses and mixing angles, in the presence of renormalisation group corrections, for various right-handed neutrino masses and mass orderings, both with and without supersymmetry. We find that the atmospheric angle, which is predicted to be near maximal in the absence of renormalisation group corrections, may receive significant corrections for some non-supers…
We study the most general extension of the MSSM Lagrangian that includes scenarios in which supersymmetry is spontaneously broken at a low scale f. The spurion that parametrizes supersymmetry breaking in the MSSM is promoted to a dynamical superfield involving the goldstino, with (and without) its scalar superpartner, the sgoldstino. The low energy effective Lagrangian is written as an expansion in terms of m_{SUSY}/sqrt{f}, where m_{SUSY} is the induced supersymmetry breaking scale, and contains, in addition to the usual MSSM Lagrangian with the soft terms, couplings involving the component f…
We study the Minimal Supersymmetric Standard Model (MSSM) with large gluino mass m_{\tilde{g}} >> 1 TeV. In particular, we discuss the LHC supersymmetry discovery signatures with n leptons + jets + E^{miss}_T, n >= 0 for the MSSM with large gluino mass. We show that for some relations among squark and neutralino masses leptonic signatures with n leptons + jets + E^{miss}_T, n >= 1 do not allow to discover supersymmetry at the LHC and the only supersymmetry discovery signature remains the signature with no leptons + jets + E^{miss}_T. Moreover, for LSP mass close to squark masses the LHC discov…
We present a five-dimensional model compactified on an interval where supersymmetry is broken by the Scherk-Schwarz mechanism. The gauge sector propagates in the bulk, two Higgs hypermultiplets are quasilocalized, and quark and lepton multiplets localized, in one of the boundaries. The effective four-dimensional theory is the MSSM with very heavy gauginos, heavy squarks and light sleptons and Higgsinos. The soft tree-level squared masses of the Higgs sector can be negative and they can (partially) cancel the positive one-loop contributions from the gauge sector. Electroweak symmetry breaking c…
We present here the results for Higgs and Supersymmetry prospective searches at the Large Hadron Collider. We show that for one year at high luminosity, Standard Model and MSSM Higgs should be observed within the theoretically expected mass range. MSUGRA and restricted phenomenological MSSM searches lead to discovery of up to 2.5 TeV squarks and gluinos.
We investigate the muon anomalous magnetic dipole moment (MDM), the muon electric dipole moment (EDM) and the lepton-flavour-violating decays of the $τ-$lepton, $τ\to μγ$ and $τ\to 3μ$, in the CP-violating Minimal Supersymmetric Standard Model (MSSM) with nonuniversal soft-supersymmetry breaking. We evaluate numerically the muon EDM and the branching ratios $B(τ\to μγ)$ and $B(τ\to 3μ)$, after taking into account the experimental constraints from the electron EDM and muon MDM. Upon imposition of the experimental limits on our theoretical predictions for the aforementioned branching ratios and …
In the framework of the MSSM the non-universal boundary conditions of soft SUSY breaking parameters are considered. Taking as input the top, bottom and Z-boson masses, the values of the gauge couplings at the EW scale and the infrared quasi-fixed points for Yukawa couplings and the soft parameters the mass of the lightest CP-even Higgs boson is found to be m_h=92.7^{+10}_{-4.9} +- 5 +- 0.4 GeV/c^2 for the low \tanβcase and m_h=125.7^{+6.4}_{-9.0} +- 5 +- 0.4 GeV/c^2 (μ> 0) or m_h =125.4^{+6.6}_{-9.0} +-5 +- 0.4 GeV/c^2 (μ< 0) in the case of large $\tanβ$.
We investigate the renormalisation group effects induced on neutrino mass and mixing parameters in a triplet-extended minimal supersymmetric standard model where a vector-like pair of hypercharge $\pm 1$ triplet superfields is added. We first rederive the one-loop renormalisation group equation for the effective neutrino mass operator and, for the case in which this operator originates solely from the decoupling of the triplets, the corresponding equations for neutrino masses, mixing parameters and CP-violating phases. We compare our results with the ones obtained previously, and quantify the …
We demonstrate that the soft supersymmetry-breaking terms in a N=1 theory can be linked by simple renormalisation group invariant relations which are valid to all orders of perturbation theory. In the special case of finite N=1 theories, the soft terms preserve finiteness to all orders.
The Fermi-Lab Collaboration has announced the results for the measurement of muon anomalous magnetic moment. Combining with the previous results by the BNL experiment, we have $4.2 σ$ deviation from the Standard Model (SM), which strongly implies the new physics around 1 TeV. To explain the muon anomalous magnetic moment naturally, we analyze the corresponding five Feynman diagrams in the Supersymetric SMs (SSMs), and show that the Electroweak Supersymmetry (EWSUSY) is definitely needed. We realize the EWSUSY in the Minimal SSM (MSSM) with Genernalized Mininal Supergravity (GmSUGRA). We find l…
Possible realistic scenarios are investigated in the minimal supersymmetric standard model (MSSM) Higgs sector extended by dimension-six effective operators. The CP-odd Higgs boson with low mass around 30--90 GeV could be consistently introduced in the regime of large threshold corrections to the effective MSSM two-doublet Higgs potential.
The predictions of the \sm and the minimal supersymmetric standard model (MSSM) for the electroweak precision parameters are discussed in the light of the recent precision data. The results from global fits yield lower $χ^2$ values in the MSSM than in the Standard model. The fits prefer regions in the MSSM parameter space with $M_2 \simeq |μ| $ and allow chargino masses higher than the present exclusion limits of LEP 1.5.
We address renormalisation group evolution issues that arise in the Anomaly Mediated Supersymmetry Breaking scenario when the tachyonic slepton problem is resolved by Fayet-Iliopoulos term contributions. We present typical sparticle spectra both for the original formulation of this idea and an alternative using Fayet-Iliopoulos terms for a U(1) compatible with a straightforward GUT embedding.
The prospects for discovering neutral Higgs bosons in the minimal supersymmetric model (MSSM) and in the minimal supergravity model at the LHC are investigated. Two special discovery channels are discussed: (i) the decay mode of the MSSM CP-odd Higgs boson into photon pairs, and (ii) the decays of neutral Higgs bosons into muon pairs in the MSSM as well as in the minimal supergravity model.
Up until now a complete scan in all phenomenologically relevant directions of the MSSM at the TeV scale for performing global fit has not been done. Given the imminent start of operation of the LHC, this is a major gap on our quest to discovering and understanding the physical implications of low energy supersymmetry. The main reason for this is the large number of parameters involved that makes it computationally extremely expensive using the traditional methods. In this talk I demonstrate that with advanced sampling techniques the problem is solvable. The results from the explored 24-paramet…
We derive bounds on leptonic double mass insertions of the type $δ^{l}_{i4} δ^{l}_{4j}$ in four generational MSSM, using the present limits on $l_i \to l_j + γ$. Two main features distinguish the rates of these processes in MSSM4 from MSSM3 : (a) tan$β$ is restricted to be very small $\lesssim 3 $ and (b) the large masses for the fourth generation leptons. In spite of small $\tanβ$, there is an enhancement in amplitudes with $llrr$($δ_{i4}^{ll}δ_{4j}^{rr}$) type insertions which pick up the mass of the fourth generation lepton, $m_{τ'}$. We find these bounds to be at least two orders of magnit…
We study the dependence of the Higgs boson mass on the supersymmetry breaking scale in the minimal supersymmetric extension of the standard Weinberg-Salam model. In particular, we find that for supersymmetry breaking scale $10^8$ GeV $\leq M_s \leq 10^{16}$ GeV and for $m^{pole}_{top} = 175 \pm 5 $ GeV the Higgs boson mass is 120 GeV $ \leq m_h \leq 160 $ GeV
We study the predictions for M_top, tan(beta) and V_cb in a popular texture ansatze for the fermion mass matrices. We do this both for the Minimal Supersymmetric Standard Model (MSSM) and for the simplest model (MSSM-BRpV) where a bilinear R-Parity violating term is added to the superpotential. We find that taking the experimental values for M_top and V_cb at 99 % C.L. and the GUT relations h_b=h_tau and (V_cb)^2=h_c/h_t within 5 %, the large tan(beta) solution, characteristic in the MSSM with bottom--tau unification, becomes disallowed. In contrast the corresponding allowed region for the MSS…
In the framework of the effective field theory approach to heavy supersymmetry radiative corrections in the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) for the effective potential decomposition up to the dimension-six operators are calculated. Symbolic expressions for the threshold corrections induced by $F$- and $D$- soft supersymmetry breaking terms are derived and the Higgs boson mass spectrum respecting the condition $m_h=$125 GeV for the lightest $CP$-even scalar is evaluated.
We have recently completed a detailed scan of the 19-dimensional parameter space of the phenomenological MSSM, i.e., the CP-conserving MSSM assuming Minimal Flavor Violation(MFV) with the first two sfermion generations degenerate. We found a large set of parameter space points that satisfied all of the existing experimental and theoretical constraints. This analysis allows us to examine the general features of the MSSM without reference to any particular SUSY breaking scenario or any other assumptions about physics at higher scales. This study opens up new possibilities for SUSY phenomenology …
We consider a supersymmetric realization of the MSSM Higgs sector, where the soft terms are promoted to supersymmetric operators and a minimal weakly coupled hidden sector is included. The model exhibits long-lived meta-stable vacua in which supersymmetry and electroweak symmetry are spontaneously broken. The spectrum contains, in addition to the usual MSSM particles and the goldstino fermion, a CP-even and a CP-odd scalar in the neutral Higgs sector corresponding to the complex sgoldstino scalar. By treating all the components of the goldstino supermultiplet dynamically and taking into accoun…
We study a supersymmetry breaking mechanism in the context of a minimal anomalous extension of the MSSM. The anomaly cancellation mechanism is achieved through suitable counterterms in the effective action, i.e. Green-Schwarz terms. We assume that the standard MSSM superpotential is perturbatively realized, i.e. all terms allowed by gauge symmetries, except for the $μ$-term which has a non-perturbative origin. The presence of this term is expected in many intersecting D-brane models which can be considered as the ultraviolet completion of our model. We show how soft supersymmetry breaking term…
Supersymmetric extensions of the standard model generically contain additional sources of CP violation. We discuss how at one loop a potentially large CP violating coupling of the lightest Higgs, h^0, to leptons is induced in the minimal supersymmetric standard model (MSSM). The CP violating couplings of h^0 in extensions of the MSSM, such as the next-to-minimal supersymmetric standard model (NMSSM) are also considered. We indicate how this CP violation might be observed; in particular a polarization-dependent production asymmetry, in the context of a muon collider, provides a means to access …
Imprints of supersymmetry at a future Z factory
研究未来Z工厂通过精密测量Z分支比来探测MSSM电弱扇区的潜力，与LHC直接搜索互补，需系统误差降至统计误差水平。
We present an overview of direct and indirect constraints in the MSSM, in CP-conserving and CP-violating MSSM scenarios, with some emphasis on the importance of combining the constraints from different sectors, namely SUSY and Higgs direct searches at the LHC, flavour physics, dark matter and electric dipole moments.
We calculate the leading contribution to the left-right asymmetry in polarized Møller scattering from the superpartners in the Minimal Supersymmetric Standard Model (MSSM), using an effective lagrangian approach. We determine the maximum asymmetry that can result from the superpartners in the MSSM under different scenarios, and discuss the feasibility of a high-precision, low-energy ($\sqrt{s}\approx 200~{\rm MeV}$) Møller scattering experiment to see supersymmetry.
These notes are an expanded version of a short course of lectures given for graduate students in particle physics at Oxford. The level was intended to be appropriate for students in both experimental and theoretical particle physics.The purpose is to present an elementary and self-contained introduction to SUSY that follows on, relatively straightforwardly, from graduate-level courses in relativistic quantum mechanics and introductory quantum field theory. The notation adopted, at least initially, is one widely used in RQM courses, rather than the `spinor calculus' (dotted and undotted indices…
We study the correlation of quantum effects on the ratios R_b and R_c within the framework of the MSSM. While in the SM the quantity R_b is in discrepancy with experiment at the 2 σlevel from below, and R_c differs from the experimental result at the 1.5 σlevel from above, the theoretical prediction for both observables could simultaneously improve in the MSSM, provided that \tanβis large enough (\tanβ\sim m_t/m_b) and there exists a light supersymmetric pseudoscalar Higgs, and also a light stop and a light chargino, all of them in the 50 GeV ballpark. In view of the masses predicted for these…
We consider the minimal supersymmetric extension of the Standard Model (MSSM) with varying amounts of non-universality in the soft supersymmetry-breaking contributions to the Higgs scalar masses. In addition to the constrained MSSM (CMSSM) in which these are universal with the soft supersymmetry-breaking contributions to the squark and slepton masses at the input GUT scale, we consider scenarios in which both the Higgs scalar masses are non-universal by the same amount (NUHM1), and scenarios in which they are independently non-universal (NUHM2). We show how the NUHM1 scenarios generalize the (…
Low-energy supersymmetry is a theoretical extension of the Standard Model of particle physics in which supersymmetry is invoked to explain the origin of the electroweak scale. In this approach, the energy scale of supersymmetry breaking can be no larger than about 1 TeV. In these lectures, a pedagogical account of softly broken supersymmetric gauge theories is presented. The minimal supersymmetric extension of the Standard Model (MSSM) is defined and constraints on its parameters are explored. The implications of supersymmetric tree-level interactions and its one-loop corrections are discussed…
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