188 research outputs found

    Heavy neutrinos and the pp→lljjpp\to lljj CMS data

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    We show that the excess in the pp→eejjpp \to ee jj CMS data can be naturally interpreted within the Minimal Left Right Symmetric model (MLRSM), keeping gL=gRg_L = g_R, if CP phases and non-degenerate masses of heavy neutrinos are taken into account. As an additional benefit, a natural interpretation of the reported ratio (14:1) of the opposite-sign (OS) pp→l±l∓jjpp\to l^\pm l^\mp jj to the same-sign (SS) pp→l±l±jjpp\to l^\pm l^\pm jj lepton signals is possible. Finally, a suppression of muon pairs with respect to electron pairs in the pp→lljjpp \to lljj data is obtained, in accordance with experimental data. If the excess in the CMS data survives in the future, it would be a first clear hint towards presence of heavy neutrinos in right-handed charged currents with specific CP phases, mixing angles and masses, which will have far reaching consequences for particle physics directions.Comment: 8 pages, 7 figures. v2: minor changes, refs added, typos corrected, version accepted for publication in PL

    Theoretical constraints on masses of heavy particles in Left-Right Symmetric Models

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    Left-Right symmetric models with general gL≠gRg_L \neq g_R gauge couplings which include bidoublet and triplet scalar multiplets are studied. Possible scalar mass spectra are outlined by imposing Tree-Unitarity, and Vacuum Stability criteria and also using the bounds on neutral scalar masses MHFCNCM_{\rm H^{ FCNC}} which assure the absence of Flavour Changing Neutral Currents (FCNC). We are focusing on mass spectra relevant for the LHC analysis, i.e., the scalar masses are around TeV scale. As all non-standard heavy particle masses are related to the vacuum expectation value (VEV) of the right-handed triplet (vRv_R), the combined effects of relevant Higgs potential parameters and MHFCNCM_{\rm H^{ FCNC}} regulate the lower limits of heavy gauge boson masses. The complete set of Renormalization Group Evolutions for all couplings are provided at the 1-loop level, including the mixing effects in the Yukawa sector. Most of the scalar couplings suffer from the Landau poles at the intermediate scale Q∌106.5Q \sim 10^{6.5} GeV, which in general coincides with violation of the Tree-Unitarity bounds.Comment: 9 pages, 5 figures, pdflatex, Matches published versio

    Star formation in the nearby universe: the ultraviolet and infrared points of view

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    This work presents the main ultraviolet (UV) and far-infrared (FIR) properties of two samples of nearby galaxies selected from the GALEX (λ=2315\lambda = 2315\AA, hereafter NUV) and IRAS (λ=60Ό\lambda = 60\mum) surveys respectively. They are built in order to get detection at both wavelengths for most of the galaxies. Star formation rate (SFR) estimators based on the UV and FIR emissions are compared. Systematic differences are found between the SFR estimators for individual galaxies based on the NUV fluxes corrected for dust attenuation and on the total IR luminosity. A combined estimator based on NUV and IR luminosities seems to be the best proxy over the whole range of values of SFR. Although both samples present similar average values of the birthrate parameter b, their star-formation-related properties are substantially different: NUV-selected galaxies tend to show larger values of bb for lower masses, SFRs and dust attenuations, supporting previous scenarios for the star formation history (SFH). Conversely, about 20% of the FIR-selected galaxies show high values of bb, SFR and NUV attenuation. These galaxies, most of them being LIRGs and ULIRGs, break down the downsizing picture for the SFH, however their relative contribution per unit volume is small in the local Universe. Finally, the cosmic SFR density of the local Universe is estimated in a consistent way from the NUV and IR luminosities.Comment: 43 pages, 13 figures, accepted for publication in Astrophysical Journal Supplement Serie

    General Gauge Mediation at the Weak Scale

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    We completely characterize General Gauge Mediation (GGM) at the weak scale by solving all IR constraints over the full parameter space. This is made possible through a combination of numerical and analytical methods, based on a set of algebraic relations among the IR soft masses derived from the GGM boundary conditions in the UV. We show how tensions between just a few constraints determine the boundaries of the parameter space: electroweak symmetry breaking (EWSB), the Higgs mass, slepton tachyons, and left-handed stop/sbottom tachyons. While these constraints allow the left-handed squarks to be arbitrarily light, they place strong lower bounds on all of the right-handed squarks. Meanwhile, light EW superpartners are generic throughout much of the parameter space. This is especially the case at lower messenger scales, where a positive threshold correction to mhm_h coming from light Higgsinos and winos is essential in order to satisfy the Higgs mass constraint.Comment: 43 pages, 20 figures, mathematica package included in the sourc

    Cosmological vacuum selection and metastable susy breaking

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    We study gauge mediation in a wide class of O'Raifeartaigh type models where supersymmetry breaking metastable vacuum is created by gravity and/or quantum corrections. We examine their thermal evolution in the early universe and the conditions under which the susy breaking vacuum can be selected. It is demonstrated that thermalization typically makes the metastable supersymmetry breaking cosmologically disfavoured but this is not always the case. Initial conditions with the spurion displaced from the symmetric thermal minimum and a small coupling to the messenger sector can result in the realization of the susy breaking vacuum even if the reheating temperature is high. We show that this can be achieved without jeopardizing the low energy phenomenology. In addition, we have found that deforming the models by a supersymmetric mass term for messengers in such a way that the susy breaking minimum and the susy preserving minima are all far away from the origin does not change the conclusions. The basic observations are expected to hold also in the case of models with an anomalous U(1) group.Comment: 28 pages, 4 figures, plain Latex, journal versio

    A Complete Model of Low-Scale Gauge Mediation

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    Recent signs of a Standard Model-like Higgs at 125 GeV point towards large A-terms in the MSSM. This presents special challenges for gauge mediation, which by itself predicts vanishing A-terms at the messenger scale. In this paper, we review the general problems that arise when extending gauge mediation to achieve large A-terms, and the mechanisms that exist to overcome them. Using these mechanisms, we construct weakly-coupled models of low-scale gauge mediation with extended Higgs-messenger couplings that generate large A-terms at the messenger scale and viable mu/B_mu-terms. Our models are simple, economical, and complete realizations of supersymmetry at the weak scale.Comment: 33 pages; v2: refs added, minor change

    Physics at a 100 TeV pp collider: beyond the Standard Model phenomena

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    This report summarises the physics opportunities in the search and study of physics beyond the Standard Model at a 100 TeV pp collider.Comment: 196 pages, 114 figures. Chapter 3 of the "Physics at the FCC-hh" Repor
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