In the context of many leptogenesis and baryogenesis scenarios, B-L (baryon minus the lepton number) is converted into B (baryon number) by non-perturbative B+L violating operators in the SU(2)_L sector. We correct a common misconversion of B-L to B in the literature in the context of supersymmetry. More specifically, kinematic effects associated with the sparticle masses can be generically important (typically a factor of 2/3 correction in mSUGRA scenarios), and in some cases, it may even flip the sign between B-L and B. We give explicit formulae for converting B-L to B for temperatures approaching the electroweak phase transition temperature from above. Enhancements of B are also possible, leading to a mild relaxation of the reheating temperature bounds coming from gravitino constraints.
I describe how under favourable circumstances the invisible axion may manifest its existence at the LHC through the sparticle spectrum; in particular through a gluino \sim \ln (M_P/m_{3/2}) times heavier than other gauginos.
We study the implications of the inverse seesaw mechanism (ISS) on the sparticle spectrum in the Constrained Minimal Supersymmetric Standard Model (CMSSM) and Non-Universal Higgs Model (NUHM2). Employing the maximal value of the Dirac Yukawa coupling involving the up type Higgs doublet provides a 2-3 GeV enhancement of the lightest CP-even Higgs boson mass. This effect permits one to have lighter colored sparticles in the CMSSM and NUHM2 scenarios with LSP neutralino, which can be tested at LHC14. We present a variety of LHC testable benchmark points with the desired LSP neutralino dark matter…
We investigate the impact of TeV-scale matter belonging to complete vectorlike multiplets of unified groups on the lightest Higgs boson in the MSSM. We find that consistent with perturbative unification and electroweak precision data the mass m_h can be as large as 160 GeV. These extended MSSM models can also render the little hierarchy problem less severe, but only for lower values of m_h < 125 GeV. We present estimates for the sparticle mass spectrum in these models.
We study in detail the particle spectrum in anomaly mediated supersymmetry breaking models in which supersymmetry breaking terms are induced by the super-Weyl anomaly. We investigate the minimal anomaly mediated supersymmetry breaking models, gaugino assisted supersymmetry breaking models, as well as models with additional residual nondecoupling D-term contributions due to an extra U(1) gauge symmetry at a high energy scale. We derive sum rules for the sparticle masses in these models which can help in differentiating between them. We also obtain the sparticle spectrum numerically, and compare…
We carry out a detailed analysis of sparticle mass spectrum in supersymmetric grand unified theories. We consider the spectroscopy of the squarks and sleptons in SU(5) and SO(10) grand unified theories, and show how the underlying supersymmetry breaking parameters of these theories can be determined from a measurement of different sparticle masses. This analysis is done analytically by integrating the one-loop renormalization group equations with appropriate boundary conditions implied by the underlying grand unified gauge group. We also consider the impact of non-universal gaugino masses on t…
The phenomenological implications of the M-theory limit in which supersymmetry is broken by the F-terms of five-brane moduli is investigated. In particular we calculate the supersymmetric spectrum subject to constraints of correct electroweak symmetry breaking. We find interesting differences especially in the squark sector compared with $M$-theory scenarios with standard embedding and weakly-coupled Calabi-Yau compactifications in the large $T$-limit.
The phenomenological implications of the eleven dimensional limit of $M$-theory (strongly coupled $E_8\times E_8$) are investigated. In particular we calculate the supersymmetric spectrum subject to constraints of correct electroweak symmetry breaking and the requirement that the lighest supersymmetric particle provides the dark matter of the universe. The $B$-soft term associated with the generation of a $μ$ term in the superpotential is calculated and its phenomenology is discussed.
We examine low energy sparticle mass-spectrum and electroweak symmetry breaking (EWSB) in the mixed modulus-anomaly mediation which is naturally realized in KKLT flux compactification. We find that the anomaly-mediation effectively lowers messenger scale in the moduli-mediation and leads to 'squeezed' mass-spectrum distinct from any known mediation mechanisms. The lightest neutralino typically becomes a mixed state of bino and higgsino or pure higgsino, which has a considerable impact on the cold dark matter physics.
The supersymmetric standard model with supergravity-inspired soft breaking terms predicts a rich pectrum of sparticles to be discovered at the SSC, LHC and NLC. Because there are more supersymmetric particles than unknown parameters, one can write down sum rules relating their masses. We discuss the pectrum of sparticles from this point of view. Some of the sum rules do not depend on the input parameters and can be used to test the consistency of the model, while others are useful in determining the input parameters of the theory. If supersymmetry is discovered but the sum rules turn out to be…
We derive sum rules for the sparticle masses in different models of supersymmetry breaking. This includes the gravity mediated models (SUGRA models) as well as models in which supersymmetry breaking terms are induced by super-Weyl anomaly (AMSB models). These sum rules can help in distinguishing between these models. In particular we obtain an upper bound on the mass of the lightest neutralino as a function of the gluino mass in SUGRA and AMSB models.
We calculate the particle spectrum of the SSM which follows from the assumption that the commonly assumed universal form of the soft supersymmetry --breaking terms is invariant under renormalisation. It is argued that this ``strong'' universality might be approached as an infra--red fixed point for the unified theory above the unification scale.
We compute the sparticle mass spectrum in the minimal four-dimensional construction that interpolates between gaugino mediation and ordinary gauge mediation.
We show compatibility with all known experimental constraints of t-b-tau Yukawa coupling unification in supersymmetric SU(4)_c x SU(2)_L x SU(2)_R which has non-universal gaugino masses and the MSSM parameter mu < 0. In particular, the relic neutralino abundance satisfies the WMAP bounds and Delta (g-2)_mu is in good agreement with the observations. We identify benchmark points for the sparticle spectra which can be tested at the LHC, including those associated with gluino and stau coannihilation channels, mixed bino-Higgsino state and the A-funnel region. We also briefly discuss prospects for…
We investigate the sparticle spectrum in models of gauge-mediated supersymmetry breaking. In these models, supersymmetry is spontaneously broken at an energy scale only a few orders of magnitude above the electroweak scale. The breakdown of supersymmetry is communicated to the standard model particles and their superpartners by "messenger" fields through their ordinary gauge interactions. We study the effects of a messenger sector in which the supersymmetry-violating F-term contributions to messenger scalar masses are comparable to the supersymmetry-preserving ones. We also argue that it is no…
Using anomalous U(1) symmetry the quark mass texture is determined uniquely. We analyze squark mass spectrum based on the above mass matrices and discuss the possibility to solve the problems of FCNC and CP caused by complex phases of soft terms, including the viewpoint of M theory.
We investigate supersymmetric SO(10) GUT model with μ<0. The requirements of top-bottom-tau Yukawa unification, correct radiative electroweak symmetry breaking and agreement with the present experimental data may be met when the soft masses of scalars and gauginos are non-universal. We show how appropriate non-universalities can easily be obtained in the SO(10) GUT broken to the Standard Model. We discuss how values of BR(b-->s γ) and (g-2)_μsimultaneously in a good agreement with the experimental data can be achieved in SO(10) model with μ<0. In the region of the parameter space preferred by …
We use the idea of partial compositeness in a minimal supersymmetric model to relate the fermion and sfermion masses. By assuming that the Higgs and third-generation matter is (mostly) elementary, while the first- and second-generation matter is (mostly) composite, the Yukawa coupling hierarchy can be explained by a linear mixing between elementary states and composite operators with large anomalous dimensions. If the composite sector also breaks supersymmetry, then composite sfermions such as selectrons are predicted to be much heavier than the lighter elementary stops. This inverted sfermion…
The supersymmetric particle spectrum is calculated in type I string theories formulated as orientifold compactifications of type IIB string theory. A string scale at an intermediate value of $10^{11}-10^{12}$ GeV is assumed and extra vector-like matter states are introduced to allow unification of gauge coupling constants to occur at this scale. The qualitative features of the spectrum are compared with Calabi-Yau compactification of the weakly coupled heterotic string and with the eleven dimensional supergravity limit of $M$-theory. Some striking differences are observed. Assuming that the li…
Recent work on calculating string theory landscape statistical predictions for the Higgs and sparticle mass spectrum from an assumed power-law soft term distribution yields an expectation for m(h)~ 125 GeV with sparticles (save light higgsinos) somewhat beyond reach of high-luminosity LHC. A recent examination of statistics of SUSY breaking in IIB string models with stabilized moduli suggests a power-law for models based on KKLT stabilization and uplifting while models based on large-volume scenario (LVS) instead yield an expected logarithmic soft term distribution. We evaluate statistical dis…
We investigate the split supersymmetry (SUSY) scenario recently proposed by Arkani-Hamed and Dimopoulos, where the scalars are heavy but the fermions are within the TeV range. We show that the sparticle spectrum in such a case crucially depends on the specific details of the mechanism underlying the SUSY breaking scheme, and the accelerator signals are also affected by it. In particular, we demonstrate in the context of a braneworld-inspired model, used as illustration in the original work, that a new fermion $ψ_X$, arising from the SUSY breaking sector, is shown to control low-energy phenomen…
We examine the spectrum of superparticles obtained from the minimal SO(10) grand unified model, where it is assumed the gauge symmetry breaking yields the Minimal Supersymmetric Standard Model (MSSM) as the effective theory at $M_{GUT}\sim 2\times 10^{16}$ GeV. In this model, unification of Yukawa couplings implies a value of $\tanβ\sim 45-55$. At such high values of $\tanβ$, assuming universality of scalar masses, the usual mechanism of radiative electroweak symmetry breaking breaks down. We show that a set of weak scale sparticle masses consistent with radiative electroweak symmetry breaking…
Grand Unified Theories (GUTs) can feature predictions for the ratios of quark and lepton Yukawa couplings at high energy, which can be tested with the increasingly precise results for the fermion masses, given at low energies. To perform such tests, the renormalization group (RG) running has to be performed with sufficient accuracy. In supersymmetric (SUSY) theories, the one-loop threshold corrections (TC) are of particular importance and, since they affect the quark-lepton mass relations, link a given GUT flavour model to the sparticle spectrum. To accurately study such predictions, we extend…
We generalize the so-called ``deflected anomaly mediation'' scenario to the case where threshold corrections of heavy messengers to the sparticle squared-masses are positive. A concrete model realizing this scenario is also presented. The tachyonic slepton problem can be fixed with only a pair of messengers. The resultant sparticle mass spectrum is quite different from that in the conventional deflected anomaly mediation scenario, but is similar to the one in the gauge mediation scenario. The lightest sparticle is mostly B-ino.
Supersymmetric (SUSY) explanation of the discrepancy between the measurement of $(g-2)_μ$ and its SM prediction puts strong upper bounds on the chargino and smuon masses. At the same time, lower experimental limits on the chargino and smuon masses, combined with the Higgs mass measurement, lead to an upper bound on the stop masses. The current LHC limits on the chargino and smuon masses (for not too compressed spectrum) set the upper bound on the stop masses of about 10 TeV. The discovery potential of the future lepton and hadron colliders should lead to the discovery of SUSY if it is responsi…
Most sparticle decay cascades envisaged at the Large Hadron Collider (LHC) involve hadronic decays of intermediate particles. We use state-of-the art techniques based on the \kt jet algorithm to reconstruct the resulting hadronic final states for simulated LHC events in a number of benchmark supersymmetric scenarios. In particular, we show that a general method of selecting preferentially boosted massive particles such as W, Z or Higgs bosons decaying to jets, using sub-jets found by the \kt algorithm, suppresses QCD backgrounds and thereby enhances the observability of signals that would othe…
We assess the future directions for the search for supersymmetry at the Large Hadron Collider in view of the new precision results on the muon anomaly by the Fermilab Collaboration. The existence of a deviation of size 4.1$σ$ from the Standard Model prediction points to light sleptons and light weakinos in the mass range of few hundred GeV while the observation of the Higgs boson mass at $\sim 125$ GeV points to squark masses lying in the few TeV range. Thus a split sparticle spectrum is indicated. We discuss the possibility of such a split sparticle spectrum in the supergravity unified model …
We approach the following question: if supersymmetry is discovered, how can we select among different supersymmetric extensions of the Standard Model? In particular, we perform an analysis of the sparticle spectrum in low-energy string effective theories, asking which observables best distinguish various scenarios. We examine scenarios differing by the fundamental string scale and concentrate on GUT and intermediate scale models. We scan over all parameters (two goldstino angles, tan beta and the gravitino mass) in each scenario, finding ratios of sparticle masses that provide the maximum disc…
The physics of moduli fields is examined in the scenario where the gravitino is relatively heavy with mass of order 10 TeV, which is favored in view of the severe gravitino problem. The form of the moduli superpotential is shown to be determined, if one imposes a phenomenological requirement that no physical CP phase arise in gaugino masses from conformal anomaly mediation. This bottom-up approach allows only two types of superpotential, each of which can have its origins in a fundamental underlying theory such as superstring. One superpotential is the sum of an exponential and a constant, whi…
The LHC has the potential not only to discover supersymmetry (SUSY), but also to permit fairly precise measurements of at least a portion of the sparticle spectrum. Proposed mass reconstruction methods rely upon either inverting invariant mass endpoint expressions or upon solving systems of mass-shell equations. These methodologies suffer from the weakness that one certain specific sparticle decay chain is assumed to account for all the events in the sample. Taking two examples of techniques utilizing mass-shell equations, it is found that also applying the wedgebox technique allows for the is…
We study the properties of the Higgs and supersymmetric particle spectrum associated with the infrared fixed point solution of the top quark mass in the MSSM. We concentrate on the possible detection of these particles, analysing the deviations from the Standard Model predictions for the leptonic and hadronic variables measured at LEP and for the decay rate $b\rightarrow sγ$. We consider the low and moderate $\tan β$ regime, and we study both, the cases of universal and non--universal soft supersymmetry breaking parameters at high energies. In the first case, for any given value of the top qua…
We survey a variety of proposals for new physics at high scales that serve to relate the multitude of soft supersymmetry breaking parameters of the MSSM. We focus on models where the new physics results in non-universal soft parameters, in sharp contrast with the usually assumed mSUGRA framework. These include {\it i}) SU(5) and SO(10) grand unified (GUT) models, {\it ii}) the MSSM plus a right-handed neutrino, {\it iii}) models with effective supersymmetry, {\it iv}) models with anomaly-mediated SUSY breaking and gaugino mediated SUSY breaking, {\it v}) models with non-universal soft terms du…
We study a generalization of anomaly-mediated supersymmetry breaking (AMSB) scenarios, under the assumption that the effects of the high-scale theory do not completely decouple and D-term type contributions can be therefore present. We investigate the effect of such possible D-term additional contributions to soft scalar masses by requiring that, for non-vanishing, renormalizable Yukawa couplings $Y^{ijk} $, the sum of squared soft supersymmetry breaking mass parameters, $M^2_{ijk} \equiv m_i^2+m_j^2+m_k^2$, is RG-invariant, in the sense that it becomes independent of the specific ultraviolet …
We discuss low energy threshold effects and calculate the sparticle masses in the context of the Minimal Supersymmetric Standard Model. We pay particular attention to the top squark and the Higgs mass parameters, and calculate the top Yukawa corrections, taking into account the successive decoupling of each particle at its threshold. We discuss the phenomenological implications in the context of the radiative symmetry breaking scenario.
The supersymmetric (SUSY) minimal SO(10) model is a well-motivated grand unified theory, where the Standard Model (SM) fermions have Yukawa couplings with only one ${\bf 10}$-plet and one $\overline{\bf 126}$-plet Higgs fields and it is highly non-trivial if the realistic quark and lepton mass matrices can be reproduced in this context. It has been known that the best fit for all the SM fermion mass matrices is achieved by a vacuum expectation value of the $\overline{\bf 126}$-plet Higgs field being at the intermediate scale of around ${\cal O}(10^{13})$ GeV. Under the presence of the SO(10) s…
We discuss the parameter spaces of supersymmetry (SUSY) scenarios taking into account the improved Higgs-mass prediction provided by FeynHiggs 2.14.1. Among other improvements, this prediction incorporates three-loop renormalization-group effects and two-loop threshold corrections, and can accommodate three separate mass scales: m_{\tilde q} (for squarks), m_{\tilde g} (for gluinos) and m_{\tildeχ} (for electroweakinos). Furthermore, it contains an improved treatment of the DRbar scalar top parameters avoiding problems with the conversion to on-shell parameters, that yields more accurate resul…
We study the possibility of discovering or excluding a light top squark (stop) based on top quark decays in the t-tbar events produced at the Fermilab Tevatron. In particular, we consider the Minimal Supersymmetric Standard Model with the sparticle spectrum m_{chi^+_1}+m_b, M_W+m_{chi^0_1}+m_b > m_{stop} > m_{chi^0_1}+m_c, where chi^0_1 is the lightest neutralino and chi^+_1 is the lightest chargino, so that t -> stop chi^0_1 and stop -> c chi^0_1. All other sparticle masses are assumed to be heavier than m_t. Such a spectrum seeks to explain the experimental values of alpha_s(M_Z^2), R_b and …
We evaluate the sparticle mass spectrum in the minimal four-dimensional construction that interpolates between gaugino and ordinary gauge mediation at the weak scale. We find that even in the hybrid case -- when the messenger scale is comparable to the mass of the additional gauge particles -- both the right-handed as well as the left-handed sleptons are lighter than the bino in the low-scale mediation regime. This implies a chain of lepton production and, consequently, striking signatures that may be probed at the LHC already in the near future.
We take a critical view of the treatment of threshold effects in SUSY spectrum computations from high-scale input. We discuss the two principal methods of (a) renormalization at a common SUSY scale versus (b) integrating out sparticles at their own mass scales. We point out problems in the implementations in public spectrum codes, together with suggestions for improvements. In concrete examples, we compare results of Isajet7.72 and Spheno2.2.3, and present the improvements done in Isajet7.73. We also comment on theoretical uncertainties. Last but not least, we outline how a consistent multisca…
The accuracy of the procedure that converts the experimentally determined electron spectrum associated with fission of the nuclear fuels ^{235}U, ^{239}Pu, ^{241}Pu, and ^{238}U into the $\barν_e$ spectrum is examined. By using calculated sets of mutually consistent spectra it is shown that the conversion procedure can result in a small $\sim$1% error provided several conditions are met. Chief among them are the requirements that the average nuclear charge <Z> as a function of the $β$ decay endpoint energy is independently known and that the $\barν_e$ spectrum is binned into bins that are seve…
We study Radiative Electroweak Symmetry Breaking in the Minimal Supersymmetric Standard Model (MSSM). We employ the 2-loop Renormalization Group equations for running masses and couplings taking into account sparticle threshold effects. The decoupling of each particle below its threshold is realized by a step function in all one-loop Renormalization Group equations (RGE). This program requires the calculation of all wavefunction, vertex and mass renormalizations for all particles involved. Adapting our numerical routines to take care of the succesive decoupling of each particle below its thres…
We critically reexamine the standard applications of the method of kinematical endpoints for sparticle mass determination. We consider the typical decay chain in supersymmetry (SUSY) squark -> neutralino -> slepton -> LSP, which yields a jet j and two leptons ln and lf. The conventional approaches use the upper kinematical endpoints of the individual distributions m_{jll}, m_{jl(lo)} and m_{jl(hi)}, all three of which suffer from parameter space region ambiguities and may lead to multiple solutions for the SUSY mass spectrum. In contrast, we do not use m_{jll}, m_{jl(lo)} and m_{jl(hi)}, and i…
Two loop renormalization group equations for dimensionless as well as dimensionful parameters are obtained for the low energy theories that result from decoupling heavy scalar particles in Split SUSY and Effective SUSY scenarios, assuming that only a single Higgs field survives at low energy. For the Effective SUSY case two scenarios are considered: first, when the only light third generation scalars are the partners of the left-handed quark doublet and the right-handed top quark --which yields the minimal matter content compatible with naturalness-- and second, when all the scalars of the thi…
We study Radiative Electroweak Symmetry Breaking in the Minimal Supersymmetric Standard Model (MSSM). We employ the 2-loop Renormalization Group equations for running masses and couplings taking into account sparticle threshold effects. The decoupling of each particle below its threshold is realized by a step function in all one-loop Renormalization Group equations (RGE). This program requires the calculation of all wavefunction, vertex and mass renormalizations for all particles involved. Adapting our numerical routines to take care of the succesive decoupling of each particle below its thres…
We consider three-loop $β$-function corrections to the sparticle spectrum in the MSSM, with particular emphasis on Snowmass Benchmark points. The three loop running has little effect on the weakly interacting particle spectrum, but for the squark masses the effect can be comparable to, or greater than, that of two loop running. We extend the analysis to the semi-perturbative unification scenario, where the impact of the three loop corrections becomes even more dramatic.
In the region of large mu^+ mu^- invariant mass, the decay spectrum of K_L -> mu^+ mu^- gamma deviates from the Dalitz pair spectrum, as a result of interference between conversion (K_L -> gamma^* gamma -> mu^+ mu^- gamma) and bremsstrahlung amplitudes. The latter is proportional to the K_L -> mu^+ mu^- matrix element, whose 2 gamma-absorptive part appears to dominate the observed K_L -> mu^+ mu^- decay rate. We examine the extent to which a scrutiny of the K_L -> mu^+ mu^- gamma spectrum in the end-point region could provide evidence on the real part of the K_L -> mu^+ mu^- amplitude. As a by…
Lepton flavour non-conserving processes are examined in the context of unified models with U(1)-family symmetries which reproduce successfully the low-energy hierarchy of the fermion mass spectrum and the Kobayashi - Maskawa mixing. These models usually imply mixing effects in the supersymmetric scalar sector. We construct the fermion and scalar mass matrices in two viable models, and calculate the mixing effects on the $μ\to eγ$, $μ\to 3 e$ and $τ\to μγ$ rare decays. The relevant constraints on the sparticle mass spectrum as well as the role of various MSSM parameters are discussed.
We show how a sparticle spectrum characteristic of anomaly mediation can arise from a theory whose Lagrangian contains no explicit mass scale. The scale of supersymmetry breaking is governed by the gravitino mass, which is the vacuum expectation value of the F-term of the conformal compensator field, and the tachyonic slepton problem is resolved by the breaking of a U(1) gauge symmetry at a scale determined by dimensional transmutation.
We construct explicit examples with a horizontal, ``anomalous'' $U(1)$ gauge group, which, in a supersymmetric extension of the standard model, reproduce qualitative features of the fermion spectrum and CKM matrix, and suppress FCNC and proton decay rates without the imposition of global symmetries. We review the motivation for such ``more'' minimal supersymmetric standard models and their predictions for the sparticle spectrum. There is a mass hierarchy in the scalar sector which is the inverse of the fermion mass hierarchy. We show in detail why DeltaS = 2 FCNC are suppressed when compared w…
Discovery of supersymmetric (SUSY) particles at the Large Hadron Collider(LHC) has been studied for the models where squarks and gluino are much heavier than the lightest supersymetric particle (LSP). In this paper, we investigate the SUSY discovery in the models with degenerated mass spectrum up to m_LSP~0.7 m_sq. Such mass spectrum is predicted in certain parameter region of the mixed modulas anomaly mediation (MMAM) model. We find that the effective transverse mass of the signal for the degenerated parameters shows the distribution similar to that of the background. Experimental sensitivity…
In supersymmetric models where the superpotential mu term is generated with mu<< m_{soft} (e.g. from radiative Peccei-Quinn symmetry breaking or compactified string models with sequestration and stabilized moduli), and where the string landscape 1. favors soft supersymmetry (SUSY) breaking terms as large as possible and 2. where the anthropic condition that electroweak symmetry is properly broken with a weak scale m_{W,Z,h}~100 GeV ({\it i.e.} not too weak of weak interactions), then these combined landscape/anthropic requirements act as an attractor pulling the soft SUSY breaking terms toward…
Selectrons may be produced in pairs at LEPII if their mass is less than about 100 GeV. Preferably, they decay into the lightest neutralino plus an electron. In a scenario where selectrons are observed at LEPII, we show that: (i) in a first stage where experimental errors are large, the measurement of the total cross section of selectron pair production, the selectron mass, and the lightest neutralino mass, allow us to validate or rule out the Minimal Supergravity Model in its simplest form, and that (ii) in a second stage where precision measurements are available, the value of $\tanβ$ can be …
We examine the dielectron invariant mass spectrum and the variation of the polarization asymmetry as a function of that mass in the event generator of the five-dimensional Bethe-Heitler differential cross section of the conversion of linearly polarized photons that we have implemented recently as a Geant4 Physics Model. We compare the results obtained with simulated samples to analytical expressions. Studies of $b \to s γ$ decays at LHC and Belle II experiments could provide hints of physics beyond the standard model in flavor-changing neutral current processes; issues have been reported in th…
Baryonic R-parity violation could explain why low-scale supersymmetry has not yet been discovered at colliders: sparticles would be hidden in the intense hadronic activity. However, if the known flavor structures are any guide, the largest baryon number violating couplings are those involving the top/stop, so a copious production of same-sign top-quark pairs is in principle possible. Such a signal, with its low irreducible background and efficient identification through same-sign dileptons, provides us with tell-tale signs of baryon number violating supersymmetry. Interestingly, this statement…
The flavor conversion of a neutrino usually occurs at densities $\lesssim G_F^{-1} ω$, whether in the ordinary matter or the neutrino medium, and on time/distance scales of order $ω^{-1}$, where $G_F$ is the Fermi weak coupling constant and $ω$ is the vacuum oscillation frequency of the neutrino. In 2005 Sawyer and more recently both he and other groups have shown that neutrino flavor conversions can occur on scales much shorter than $ω^{-1}$ in a very dense, anisotropic neutrino gas such as that in a core-collapse supernova or a binary neutron star merger. It has also been suggested that the …
We analyse the mass spectrum of the Constrained Minimal Supersymmetric Standard Model at the low tan beta fixed point. We find that the model only satisfies experimental and dark matter bounds in regions where the vacuum is meta-stable -- ie where it violates `unbounded from below' (UFB) bounds. Adding a small amount of R-parity violation solves these problems but the absolute upper bound on the lowest higgs mass m_{h^0}<97 GeV remains. We present the predicted sparticle mass spectrum as a function of the gluino mass m_g.
The neutrino spin-flavor conversion of \barν_e and ν_μwhich is induced by the interaction of the Majorana neutrino magnetic moment and magnetic fields in the collapse-driven supernova is investigated in detail. We calculate the conversion probability by using the latest precollapse models of Woosley and Weaver (1995), and also those of Nomono and Hashimoto (1988), changing the stellar mass and metallicity in order to estimate the effect of the astrophysical uncertainties. Contour maps of the conversion probability are given for all the models as a function of neutrino mass squared difference a…
In this article, we investigate the $μ^-\to e^-X$ process in a muonic atom, where $X$ is a light neutral boson. By calculating the spectrum of the emitted electron for several cases, we discuss the model-discriminating power of the process. We report the strong model dependence of the spectrum near a high-energy endpoint. Our findings show that future experiments using muonic atoms are helpful to identify the properties of exotic bosons.
We have determined in detail the electron spectrum in the decay of bound muons. These results are especially relevant for the upcoming muon-electron conversion experiments.
