171 research outputs found
Hedge Fund Boards and the Market for Independent Directors
We provide the first examination of hedge fund boards and their directors. The majority of directorships are held by extremely busy independent directors. These directors are sought after by funds because they have more reputational capital at stake, making them independent and credible monitors whose presence can certify fund quality to investors. Busy independent directors are more likely to be hired by high quality funds, and their departure from the board is associated with investor withdrawals. Moreover, funds with busy independent directors are less likely to commit fraud, abuse discretionary liquidity restrictions, or engage in performance-based risk shifting
Disentangling Dimension Six Operators through Di-Higgs Boson Production
New physics near the TeV scale can generate dimension-six operators that
modify the production rate and branching ratios of the Higgs boson. Here, we
show how Higgs boson pair production can yield complementary information on
dimension-six operators involving the gluon field strength. For example, the
invariant mass distribution of the Higgs boson pair can show the extent to
which the masses of exotic TeV-scale quarks come from electroweak symmetry
breaking. We discuss both the current Tevatron bounds on these operators and
the most promising LHC measurement channels for two different Higgs masses: 120
GeV and 180 GeV. We argue that the operators considered in this paper are the
ones most likely to yield interesting Higgs pair physics at the LHC.Comment: 20 pages, 7 figures; v2: to match JHEP versio
A Definitive Signal of Multiple Supersymmetry Breaking
If the lightest observable-sector supersymmetric particle (LOSP) is charged
and long-lived, then it may be possible to indirectly measure the Planck mass
at the LHC and provide a spectacular confirmation of supergravity as a symmetry
of nature. Unfortunately, this proposal is only feasible if the gravitino is
heavy enough to be measured at colliders, and this condition is in direct
conflict with constraints from big bang nucleosynthesis (BBN). In this work, we
show that the BBN bound can be naturally evaded in the presence of multiple
sectors which independently break supersymmetry, since there is a new decay
channel of the LOSP to a goldstino. Certain regions of parameter space allow
for a direct measurement of LOSP decays into both the goldstino and the
gravitino at the LHC. If the goldstino/gravitino mass ratio is measured to be
2, as suggested by theory, then this would provide dramatic verification of the
existence of multiple supersymmetry breaking and sequestering. A variety of
consistent cosmological scenarios are obtained within this framework. In
particular, if an R symmetry is imposed, then the gauge-gaugino-goldstino
interaction vertices can be forbidden. In this case, there is no bound on the
reheating temperature from goldstino overproduction, and thermal leptogenesis
can be accommodated consistently with gravitino dark matter.Comment: 10 pages, 5 figures, title changed to match the version published in
JHE
Identifying Boosted Objects with N-subjettiness
We introduce a new jet shape -- N-subjettiness -- designed to identify
boosted hadronically-decaying objects like electroweak bosons and top quarks.
Combined with a jet invariant mass cut, N-subjettiness is an effective
discriminating variable for tagging boosted objects and rejecting the
background of QCD jets with large invariant mass. In efficiency studies of
boosted W bosons and top quarks, we find tagging efficiencies of 30% are
achievable with fake rates of 1%. We also consider the discovery potential for
new heavy resonances that decay to pairs of boosted objects, and find
significant improvements are possible using N-subjettiness. In this way,
N-subjettiness combines the advantages of jet shapes with the discriminating
power seen in previous jet substructure algorithms.Comment: 26 pages, 26 figures, 2 tables; v2: references added; v3: discussion
of results extende
Proposed Lunar Measurements of -Process Radioisotopes to Distinguish Origin of Deep-sea 244Pu
244Pu has recently been discovered in deep-sea deposits spanning the past 10
Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is
among the heaviest -process products, and we consider whether it was created
in the supernovae, which is disfavored by nucleosynthesis simulations, or in an
earlier kilonova event that seeded 244Pu in the nearby interstellar medium that
was subsequently swept up by the supernova debris. We discuss how these
possibilities can be probed by measuring 244Pu and other -process
radioisotopes such as 129I and 182Hf, both in lunar regolith samples returned
to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits.Comment: Extensive rewrite of v1 with added emphasis of lunar sample return
missions, including Artemis and Chang'e. 11 pages, 4 figures, 2 tabl
Do primary care medical homes facilitate care transitions after psychiatric discharge for patients with multiple chronic conditions?
Primary-care-based medical homes may facilitate care transitions for persons with multiple chronic conditions (MCC) including serious mental illness. The purpose of this manuscript is to assess outpatient follow-up rates with primary care and mental health providers following psychiatric discharge by medical home enrollment and medical complexity
Do Medical Homes Offer Improved Diabetes Care for Medicaid Enrollees with Co-occurring Schizophrenia?
To determine whether Medicaid recipients with co-occurring diabetes and schizophrenia that are medical-home-enrolled are more likely to receive guideline-concordant diabetes care than those who are not medical-home-enrolled, controlling for confounders
First Results from the DRIFT-IIa Dark Matter Detector
Data from the DRIFT-IIa directional dark matter experiment are presented,
collected during a near continuous 6 month running period. A detailed
calibration analysis comparing data from gamma-ray, x-ray and neutron sources
to a GEANT4 Monte Carlo simulations reveals an efficiency for detection of
neutron induced recoils of 94+/-2(stat.)+/-5(sys.)%. Software-based cuts,
designed to remove non-nuclear recoil events, are shown to reject 60Co
gamma-rays with a rejection factor of better than 8x10-6 for all energies above
threshold. An unexpected event population has been discovered and is shown here
to be due to the alpha-decay of 222Rn daughter nuclei that have attached to the
central cathode. A limit on the flux of neutrons in the Boulby Underground
Laboratory is derived from analysis of unshielded and shielded data.Comment: 43 pages, 14 figures, submitted to Astroparticle Physic
Goldstini
Supersymmetric phenomenology has been largely bound to the hypothesis that
supersymmetry breaking originates from a single source. In this paper, we relax
this underlying assumption and consider a multiplicity of sectors which
independently break supersymmetry, thus yielding a corresponding multiplicity
of goldstini. While one linear combination of goldstini is eaten via the
super-Higgs mechanism, the orthogonal combinations remain in the spectrum as
physical degrees of freedom. Interestingly, supergravity effects induce a
universal tree-level mass for the goldstini which is exactly twice the
gravitino mass. Since visible sector fields can couple dominantly to the
goldstini rather than the gravitino, this framework allows for substantial
departures from conventional supersymmetric phenomenology. In fact, this even
occurs when a conventional mediation scheme is augmented by additional
supersymmetry breaking sectors which are fully sequestered. We discuss a number
of striking collider signatures, including various novel decay modes for the
lightest observable-sector supersymmetric particle, gravitinoless
gauge-mediated spectra, and events with multiple displaced vertices. We also
describe goldstini cosmology and the possibility of goldstini dark matter.Comment: 14 pages, 7 figures; references adde
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