73,020 research outputs found
Values-Based Leadership in a Time of Values Confusion
Values-based leadership is slipping, perhaps morphing into an ill-defined expediency without the weight or anchor of moral principles while neglecting common decency, genuine care for others, and a vision of democracy as a moral egalitarianism. Values, without a moral anchor, can easily slip into ethical relativity and narcissistic navel-gazing where a moral view of others hangs hopelessly by the threads of expedient decision making. This we see in the current political and business climate of 2018 as we live and work in an atmosphere of selfishness ignoring self-giving service to others. Will this last, or will we be able to revive our democratic ideals and moral principles and transpose these into our everyday lives, business practices, and political processes
Mirror Mediation
I show that the effective action of string compactifications has a structure
that can naturally solve the supersymmetric flavour and CP problems. At leading
order in the g_s and \alpha' expansions, the hidden sector factorises. The
moduli space splits into two mirror parts that depend on Kahler and complex
structure moduli. Holomorphy implies the flavour structure of the Yukawa
couplings arises in only one part. In type IIA string theory flavour arises
through the Kahler moduli sector and in type IIB flavour arises through the
complex structure moduli sector. This factorisation gives a simple solution to
the supersymmetric flavour and CP problems: flavour physics is generated in one
sector while supersymmetry is broken in the mirror sector. This mechanism does
not require the presence of gauge, gaugino or anomaly mediation and is
explicitly realised by phenomenological models of IIB flux compactifications.Comment: 33 pages, 1 figure; v2: typos, references, minor correction
The de Sitter swampland conjecture and supersymmetric AdS vacua
It has recently been conjectured that string theory does not admit de Sitter
critical points. This note points out that in several cases, including KKLT or
racetrack models, this statement is equivalent to the absence of supersymmetric
Minkowski or AdS solutions. This equivalence arises from establishing the
positivity of the potential in a large-radius limit, requiring a turnover of
the potential before reaching an AdS vacuum. For example, this conjecture is
incompatible with the simplest 1-modulus KKLT AdS supersymmetric solution.Comment: Prepared for submission to Int. Journ. Mod. Phys. A; v2. added
references and more discussio
The QCD Axion and Moduli Stabilisation
We investigate the conditions for a QCD axion to coexist with stabilised
moduli in string compactifications. We show how the simplest approaches to
moduli stabilisation give unacceptably large masses to the axions. We observe
that solving the F-term equations is insufficient for realistic moduli
stabilisation and give a no-go theorem on supersymmetric moduli stabilisation
with unfixed axions applicable to all string compactifications and relevant to
much current work. We demonstrate how nonsupersymmetric moduli stabilisation
with unfixed axions can be realised. We finally outline how to stabilise the
moduli such that f_a is within the allowed window 10^9 GeV < f_a < 10^{12} GeV,
with f_a ~ \sqrt{M_{SUSY} M_P}.Comment: 36 pages; v2: extended discussion of cosmological bound on f_a,
references added, version accepted by journal; v3. factor of 2 correcte
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