12,761 research outputs found
Radiative Decays of the Higgs Boson to a Pair of Fermions
We revisit the radiative decays of the Higgs boson to a fermion pair
where denotes a fermion in the Standard Model
(SM). We include the chirality-flipping diagrams via the Yukawa couplings at
the order , the chirality-conserving contributions
via the top-quark loops of the order , and the
electroweak loops at the order . The QED correction is
about and contributes to the running of fermion
masses at a similar level, which should be taken into account for future
precision Higgs physics. The chirality-conserving electroweak-loop processes
are interesting from the observational point of view. First, the branching
fraction of the radiative decay is about a half of
that of , and that of is more than
four orders of magnitude larger than that of , both of which
reach about . The branching fraction of is
of the order . All the leptonic radiative decays are potentially
observable at the LHC Run 2 or the HL-LHC. The kinematic distributions for the
photon energy or the fermion pair invariant mass provide non-ambiguous
discrimination for the underlying mechanisms of the Higgs radiative decay. We
also study the process and evaluate the observability at
the LHC. We find it comparable to the other related studies and better than the
channel in constraining the charm-Yukawa coupling.Comment: 23 pages, 6 figures, 6 tables; Minor corrections, references updated,
version published in JHE
News, liquidity dynamics and intraday jumps: evidence from the HUF/EUR market
We study intraday jumps on a pure limit order FX market by linking them to news announcements and liquidity shocks. First, we show that jumps are frequent and contribute greatly to the return volatility. Nearly half of the jumps can be linked with scheduled and unscheduled news announcements. Furthermore, we show that jumps are information based, whether they are linked with news announcements or not. Prior to jumps, liquidity does not deviate from its normal level, nor do liquidity shocks offer any predictive power for jump occurrence. Jumps emerge not as a result of unusually low liquidity but rather as a result of an unusually high demand for immediacy concentrated on one side of the book. During and after the jump, a dynamic order placement process emerges: some participants endogenously become liquidity providers and absorb the increased demand for immediacy. We detect an interesting asymmetry and find the liquidity providers to be more reluctant to add liquidity when confronted with a news announcement around the jump. Further evidence shows that participants submit more limit orders relative to market orders after a jump. Consequently, the informational role of order flow becomes less pronounced in the thick order book after the jump
Graph Estimation From Multi-attribute Data
Many real world network problems often concern multivariate nodal attributes
such as image, textual, and multi-view feature vectors on nodes, rather than
simple univariate nodal attributes. The existing graph estimation methods built
on Gaussian graphical models and covariance selection algorithms can not handle
such data, neither can the theories developed around such methods be directly
applied. In this paper, we propose a new principled framework for estimating
graphs from multi-attribute data. Instead of estimating the partial correlation
as in current literature, our method estimates the partial canonical
correlations that naturally accommodate complex nodal features.
Computationally, we provide an efficient algorithm which utilizes the
multi-attribute structure. Theoretically, we provide sufficient conditions
which guarantee consistent graph recovery. Extensive simulation studies
demonstrate performance of our method under various conditions. Furthermore, we
provide illustrative applications to uncovering gene regulatory networks from
gene and protein profiles, and uncovering brain connectivity graph from
functional magnetic resonance imaging data.Comment: Extended simulation study. Added an application to a new data se
Dark Matter Blind Spots at One-Loop
We evaluate the impact of one-loop electroweak corrections to the
spin-independent dark matter (DM) scattering cross-section with nucleons
(), in models with a so-called blind spot for direct
detection, where the leading-order prediction for the relevant DM coupling to
the Higgs boson, and therefore , are vanishingly small.
Adopting a simple illustrative scenario in which the DM state results from the
mixing of electroweak singlet and doublet fermions, we compute the relevant
higher order corrections to the scalar effective operator contributions to
, stemming from both triangle and box diagrams involving the
SM and dark sector fields. It is observed that in a significant region of the
singlet-doublet model-space, the one-loop corrections ``unblind'' the
tree-level blind spots and lead to detectable SI scattering rates at future
multi-ton scale liquid Xenon experiments, with reaching
values up to a few times , for a weak scale DM with
Yukawa couplings. Furthermore, we find that there always
exists a new SI blind spot at the next-to-leading order, which is
perturbatively shifted from the leading order one in the singlet-doublet mass
parameters. For comparison, we also present the tree-level spin-dependent
scattering cross-sections near the SI blind-spot region, that could lead to a
larger signal. Our results can be mapped to the blind-spot scenario for
bino-Higgsino DM in the MSSM, with other sfermions, the heavier Higgs boson,
and the wino decoupled.Comment: 20 pages, 5 figures; Minor corrections, references updated, version
published in JHE
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