7,642 research outputs found
The goldstone and goldstino of supersymmetric inflation
We construct the minimal effective field theory (EFT) of supersymmetric
inflation, whose field content is a real scalar, the goldstone for
time-translation breaking, and a Weyl fermion, the goldstino for supersymmetry
(SUSY) breaking. The inflating background can be viewed as a single
SUSY-breaking sector, and the degrees of freedom can be efficiently
parameterized using constrained superfields. Our EFT is comprised of a chiral
superfield X_NL containing the goldstino and satisfying X_NL^2 = 0, and a real
superfield B_NL containing both the goldstino and the goldstone, satisfying
X_NL B_NL = B_NL^3 = 0. We match results from our EFT formalism to existing
results for SUSY broken by a fluid background, showing that the goldstino
propagates with subluminal velocities. The same effect can also be derived from
the unitary gauge gravitino action after embedding our EFT in supergravity. If
the gravitino mass is comparable to the Hubble scale during inflation, we
identify a new parameter in the EFT related to a time-dependent phase of the
gravitino mass parameter. We briefly comment on the leading contributions of
goldstino loops to inflationary observables.Comment: 32 pages, 2 figures. v3: clarifications and references added. Matches
JHEP version. v2: typos fixed, footnote and references adde
Can the Market Add and Subtract? Mispricing in Tech Stock Carve-Outs
Recent equity carve-outs in US technology stocks appear to violate a basic premise of financial theory: identical assets have identical prices. In our 1998-2000 sample, holders of a share of company A are expected to receive x shares of company B, but the price of A is less than x times the price of B. A prominent example involves 3Com and Palm. Arbitrage does not eliminate these blatant mispricing due to short sale constraints, so that B is overpriced but expensive or impossible to sell short. Evidence from options prices shows that shorting costs are extremely high, eliminating exploitable arbitrage opportunities.
Constraining the Axion Portal with B -> K l+ l-
We investigate the bounds on axionlike states from flavor-changing neutral
current b->s decays, assuming the axion couples to the standard model through
mixing with the Higgs sector. Such GeV-scale axions have received renewed
attention in connection with observed cosmic ray excesses. We find that
existing B->K l+ l- data impose stringent bounds on the axion decay constant in
the multi-TeV range, relevant for constraining the "axion portal" model of dark
matter. Such bounds also constrain light Higgs scenarios in the next-to-minimal
supersymmetric standard model. These bounds can be improved by dedicated
searches in B-factory data and at LHCb.Comment: 7 pages, 4 figures; v2: to match version to appear in PR
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