2,769 research outputs found
Higher Dimensional Effective Operators for Direct Dark Matter Detection
We discuss higher dimensional effective operators describing interactions
between fermionic dark matter and Standard Model particles. They are typically
suppressed compared to the leading order effective operators, which can explain
why no conclusive direct dark matter detection has been made so far. The
ultraviolet completions of the effective operators, which we systematically
study, require new particles. These particles can potentially have masses at
the TeV scale and can therefore be phenomenologically interesting for LHC
physics. We demonstrate that the lowest order options require Higgs-portal
interactions generated by dimension six operators. We list all possible
tree-level completions with extra fermions and scalars, and we discuss the LHC
phenomenology of a specific example with extra heavy fermion doublets.Comment: 27 pages, 11 figures, 3 table
Chemical Landmark 2011 – Designation of the Laboratory of Jean-Charles Galissard de Marignac in Geneva: SCNAT
Neutrino mass from higher than d=5 effective operators in SUSY, and its test at the LHC
We discuss neutrino masses from higher than d=5 effective operators in a
supersymmetric framework, where we explicitly demonstrate which operators could
be the leading contribution to neutrino mass in the MSSM and NMSSM. As an
example, we focus on the d=7 operator L L H_u H_u H_d H_u, for which we
systematically derive all tree-level decompositions. We argue that many of
these lead to a linear or inverse see-saw scenario with two extra neutral
fermions, where the lepton number violating term is naturally suppressed by a
heavy mass scale when the extra mediators are integrated out. We choose one
example, for which we discuss possible implementations of the neutrino flavor
structure. In addition, we show that the heavy mediators, in this case SU(2)
doublet fermions, may indeed be observable at the LHC, since they can be
produced by Drell-Yan processes and lead to displaced vertices when they decay.
However, the direct observation of lepton number violating processes is on the
edge at LHC.Comment: 24 pages, 5 figures, 6 table
THE EFFECT OF GOOD CORPORATE GOVERNANCE AND FOREIGN OWNERSHIP AS A MODERATING VARIABLES ON THE BOARD INTERLOCKING ON FINANCIAL PERFORMANCE
The aims of this research is to analyze the effect of number of board interlocking, board size, family board participation, board independence, control variable such as firm size, firm age, and leverage, and moderate foreign ownership to number of board interlocking towards financial firm perfomance using ROA and Tobin’s Q as a proxy in non financial sector companies listed in Indonesia Stock Exchange (BEI) in period 2014-2018. This research uses quantitative approach with two least square regression analysis model. The sample used in this research is firms which are listed on the non financial in Indonesia Stock Exchange (IDX) on 2014-2018 period. The number of final samples used in this study were 366 business entities with 1830 observations. The findings result of this research indicate that concurrent commissioner positions have positive and significant effect towards ROA in non financial sector companies BEI on the period 2014-2018, while independent commissioners, family of commissioners, board size, and the interaction of multiple positions of commissioners with foreign ownership have insignificant effect towards ROA in non financial sector companies BEI on the period 2014-2018. Then variables independent commissioners, board size of commissioners, and the interaction of multiple positions of commissioner with foreign ownership have positive and significant effect towards Tobin’s Q in non financial sector companies BEI on the period 2014-2018, while the family of commissioners and concurrent commissioner positions have insignificant effect towards ROA in non financial sector companies BEI on the period 2014-2018
A new Nigerian hunter snail species related to Ennea serrata d'Ailly, 1896 (Gastropoda, Pulmonata, Streptaxidae) with notes on the West African species attributed to Parennea Pilsbry, 1919
Ennea nigeriensis sp. n. is described from southeastern Nigeria on the basis of external and internal shell morphology. Following Pilsbry's formal criteria of a single palatal fold and corresponding external furrow, the new species may be assigned to Parennea. Ennea nigeriensis sp. n. exhibits substantial similarity with E. serrata, a species from Cameroon, in the cylindrical shell shape, crenulate suture, and internal shell morphology, indicating that the two species are closely related. CT scanning confirmed the presence of only a single palatal fold in E. nigeriensis sp. n. and two in E. serrata. In spite of this, the Nigerian species is provisionally assigned to Ennea rather than Parennea, suggesting that the characters used to define Ennea and Parennea are insufficient to delimit natural groups of species. The holotype of E. serrata is examined for the first time since its description in 1896 and a redescription of the species is provided based on the two shells hitherto known.
Study of the original specimens recorded as Ptychotrema (Parennea) sulciferum by Degner from Liberia reveals these to belong to Ennea cf. thompsonae. The Nigerian shell recorded by van Bruggen as Ptychotrema (Parennea) aequatoriale proved to be a specimen of Ennea cf. perforata. As a result, no species attributable to Parennea now appear to be known in West Africa; in contrast, numerous species are known from central and eastern Africa
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