Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userLepton flavor violation in the supersymmetric seesaw model after the LHC 8 TeV run
197
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We study the lepton flavor violation in the supersymmetric seesaw model taking into account recent experimental improvements, especially for the Higgs boson mass measurement, direct searches of superpartners and the rare decay of B_s -> mu+ mu- at the LHC, the neutrino mixing angle of theta_{13} at the neutrino experiments, and the search of mu -> e gamma at the MEG experiment. We obtain the latest constraints on the parameters in the supersymmetry breaking terms and study the effect on the lepton flavor violating decays of tau -> mu gamma and mu -> e gamma. In particular, we consider two kinds of assumption on the structures in the Majorana mass matrix and the neutrino Yukawa matrix. In the case of the Majorana mass matrix proportional to the unit matrix, allowing non-vanishing CP violating parameters in the neutrino Yukawa matrix, we find that the branching ratio of tau -> mu gamma can be larger than 10^{-9} within the improved experimental limit of mu -> e gamma. We also consider the neutrino Yukawa matrix that includes the mixing only in the second and third generations, and find that a larger branching ratio of tau -> mu gamma than 10^{-9} is possible with satisfying the recent constraints.
rate research
Read More
Different mechanisms operate in various regions of the MSSM parameter space to bring the relic density of the lightest neutralino, neutralino_1, assumed here to be the LSP and thus the Dark Matter (DM) particle, into the range allowed by astrophysics and cosmology. These mechanisms include coannihilation with some nearly-degenerate next-to-lightest supersymmetric particle (NLSP) such as the lighter stau (stau_1), stop (stop_1) or chargino (chargino_1), resonant annihilation via direct-channel heavy Higgs bosons H/A, the light Higgs boson h or the Z boson, and enhanced annihilation via a larger Higgsino component of the LSP in the focus-point region. These mechanisms typically select lower-dimensional subspaces in MSSM scenarios such as the CMSSM, NUHM1, NUHM2 and pMSSM10. We analyze how future LHC and direct DM searches can complement each other in the exploration of the different DM mechanisms within these scenarios. We find that the stau_1 coannihilation regions of the CMSSM, NUHM1, NUHM2 can largely be explored at the LHC via searches for missing E_T events and long-lived charged particles, whereas their H/A funnel, focus-point and chargino_1 coannihilation regions can largely be explored by the LZ and Darwin DM direct detection experiments. We find that the dominant DM mechanism in our pMSSM10 analysis is chargino_1 coannihilation: {parts of its parameter space can be explored by the LHC, and a larger portion by future direct DM searches.
Neutrino are massless in the Standard Model. The most popular mechanism to generate neutrino masses are the type I and type II seesaw, where right-handed neutrinos and a scalar triplet are augmented to the Standard Model, respectively. In this work, we discuss a model where a type I + II seesaw mechanism naturally arises via spontaneous symmetry breaking of an enlarged gauge group. Lepton flavor violation is a common feature in such setup and for this reason, we compute the model contribution to the $mu rightarrow egamma$ and $mu rightarrow 3e$ decays. Moreover, we explore the connection between the neutrino mass ordering and lepton flavor violation in perspective with the LHC, HL-LHC and HE-LHC sensitivities to the doubly charged scalar stemming from the Higgs triplet. Our results explicitly show the importance of searching for signs of lepton flavor violation in collider and muon decays. The conclusion about which probe yields stronger bounds depends strongly on the mass ordering adopted, the absolute neutrino masses and which much decay one considers. In the 1-5 TeV mass region of the doubly charged scalar, lepton flavor violation experiments and colliders offer orthogonal and complementary probes. Thus if a signal is observed in one of the two new physics searches, the other will be able to assess whether it stems from a seesaw framework.
We consider the minimal supersymmetric standard model within a scenario of large $tanbeta$ and heavy squarks and gluinos, with masses of the heavy neutral Higgs bosons below the TeV scale. We allow for the presence of a large, model independent, source of lepton flavor violation (LFV) in the slepton mass matrix in the $tau-mu$ sector by the mass insertion approximation. We constrain the parameter space using the $tau$ LFV decays together with the $B$-mesons physics observables, the anomalous magnetic moment of the muon and the dark matter relic density. We further impose the exclusion limit on spin-independent neutralino-nucleon scattering from CDMS and the recent CDF limit from direct search of the heavy neutral Higgs at the TEVATRON. We re-examine the prospects for the detection of Higgs mediated LFV at LHC, at a photon collider and in LFV decays of the $tau$ such as $tautomueta$, $tautomugamma$. We find rates probably too small to be observed at future experiments if models have to accommodate for the relic density measured by WMAP and explain the $(g-2)_{mu}$ anomaly: better prospects are found if these two constraints are applied only as upper bounds. The spin-independent neutralino-nucleon cross section in the studied constrained parameter space is just below the present CDMS limit and the running XENON100 experiment will cover the region of the parameter space where the lightest neutralino has large gaugino-higgsino mixing.
Till today lepton flavor violation has not been observed in processes involving charged leptons. Hence, a search for it is under hot pursuit both in theories and experiments. In our current work, we investigate the rates of rare decay processes such as $tau rightarrow mu gamma$ in SU(5) SUSY GUT and found that it satisfies the current bound and is one order below the projected sensitivity. This gives a corroborative argument for the influence of the large top-Yukawa coupling at the GUT scale ($lambda_{tG}$) on flavor violating decay rates of leptons which are investigable at low energy electroweak scale $M_Z$. Secondly, we discuss the decay rates of $mu rightarrow e gamma$ & $tau rightarrow mu gamma$ in MSSM with added right handed neutrino superfields. From this, we set bounds on $tan beta$ and further, we investigate the mass of $tilde{chi}^0 _1$, the LSP, using the rates of LFV decays. In the calculations, the latest updated data from LHC, neutrino oscillation experiments and constraints on branching ratios from the MEG experiment have been used.
We make a frequentist analysis of the parameter space of the NUHM2, in which the soft supersymmetry (SUSY)-breaking contributions to the masses of the two Higgs multiplets, $m^2_{H_{u,d}}$, vary independently from the universal soft SUSY-breaking contributions $m^2_0$ to the masses of squarks and sleptons. Our analysis uses the MultiNest sampling algorithm with over $4 times 10^8$ points to sample the NUHM2 parameter space. It includes the ATLAS and CMS Higgs mass measurements as well as their searches for supersymmetric jets + MET signals using the full LHC Run~1 data, the measurements of $B_s to mu^+ mu^-$ by LHCb and CMS together with other B-physics observables, electroweak precision observables and the XENON100 and LUX searches for spin-independent dark matter scattering. We find that the preferred regions of the NUHM2 parameter space have negative SUSY-breaking scalar masses squared for squarks and sleptons, $m_0^2 < 0$, as well as $m^2_{H_u} < m^2_{H_d} < 0$. The tension present in the CMSSM and NUHM1 between the supersymmetric interpretation of $g_mu - 2$ and the absence to date of SUSY at the LHC is not significantly alleviated in the NUHM2. We find that the minimum $chi^2 = 32.5$ with 21 degrees of freedom (dof) in the NUHM2, to be compared with $chi^2/{rm dof} = 35.0/23$ in the CMSSM, and $chi^2/{rm dof} = 32.7/22$ in the NUHM1. We find that the one-dimensional likelihood functions for sparticle masses and other observables are similar to those found previously in the CMSSM and NUHM1.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
