3,709 research outputs found
QCD at Finite temperature and density with staggered and Wilson quarks
One of the most challenging issues in particle physics is to study QCD in
extreme conditions. Precise determination of the QCD phase diagram on
temperature and chemical potential plane will provide valuable
information for quark-gluon plasma (QGP) and neutron star physics. We present
results for phase structure on the plane for lattice QCD with Wilson
fermions from strong coupling Hamiltonian analysis and Kogut-Susskind Fermions
from Lagrangian Monte Carlo simulations at intermediate coupling.Comment: Lattice 2004 (nonzero
Optimization and Abstraction: A Synergistic Approach for Analyzing Neural Network Robustness
In recent years, the notion of local robustness (or robustness for short) has
emerged as a desirable property of deep neural networks. Intuitively,
robustness means that small perturbations to an input do not cause the network
to perform misclassifications. In this paper, we present a novel algorithm for
verifying robustness properties of neural networks. Our method synergistically
combines gradient-based optimization methods for counterexample search with
abstraction-based proof search to obtain a sound and ({\delta}-)complete
decision procedure. Our method also employs a data-driven approach to learn a
verification policy that guides abstract interpretation during proof search. We
have implemented the proposed approach in a tool called Charon and
experimentally evaluated it on hundreds of benchmarks. Our experiments show
that the proposed approach significantly outperforms three state-of-the-art
tools, namely AI^2 , Reluplex, and Reluval
M-Theory Phenomenology and See-Saw Mechanisms
A version of M-theory phenomenology is proposed in which the symmetry is
based on the group . Each SO(10) group acts on a single generation. The is
regarded as the hidden sector symmetry group. The supersymmetry is broken in
the hidden sector by the Fayet-Iliopoulos -term for each group. The -term
is needed also to circumvent the powerful non-renormalization theorem since the
is broken down to the usual SO(10) by the
pair condensation of certain messenger sector multiplets. The exchange of U(1)
gauge bosons gives an attractive force for the pair to be created and
condensed. The off-diagonal mass matrix elements among the generations in these
messenger sector multiplets are the source of the flavor dynamics including the
CP violation. The pair condensation of another multiplet in the messenger
sector leads to the doublet-triplet splitting. The SO(10) decuplet Higgs
couples only to one of the generations. The other couplings should, therefore,
be calculated as higher order corrections. We present our preliminary results
on the calculation of the mass matrices and the mixing angles for leptons and
quarks in this model.Comment: 19 pages, 16 figures, Talk given at Neutrino Mass and See-Saw
Mechanism, Fujihara Semina
The web of Calabi-Yau hypersurfaces in toric varieties
Recent results on duality between string theories and connectedness of their
moduli spaces seem to go a long way toward establishing the uniqueness of an
underlying theory. For the large class of Calabi-Yau 3-folds that can be
embedded as hypersurfaces in toric varieties the proof of mathematical
connectedness via singular limits is greatly simplified by using polytopes that
are maximal with respect to certain single or multiple weight systems. We
identify the multiple weight systems occurring in this approach. We show that
all of the corresponding Calabi-Yau manifolds are connected among themselves
and to the web of CICY's. This almost completes the proof of connectedness for
toric Calabi-Yau hypersurfaces.Comment: TeX, epsf.tex; 24 page
Duality cascades and duality walls
We recast the phenomenon of duality cascades in terms of the Cartan matrix
associated to the quiver gauge theories appearing in the cascade. In this
language, Seiberg dualities for the different gauge factors correspond to Weyl
reflections. We argue that the UV behavior of different duality cascades
depends markedly on whether the Cartan matrix is affine ADE or not. In
particular, we find examples of duality cascades that can't be continued after
a finite energy scale, reaching a "duality wall", in terminology due to M.
Strassler. For these duality cascades, we suggest the existence of a UV
completion in terms of a little string theory.Comment: harvmac, 24 pages, 4 figures. v2: references added. v3: reference
adde
Gluino Decay as a Probe of High Scale Supersymmetry Breaking
A supersymmetric standard model with heavier scalar supersymmetric particles
has many attractive features. If the scalar mass scale is O(10 - 10^4) TeV, the
standard model like Higgs boson with mass around 125 GeV, which is strongly
favored by the LHC experiment, can be realized. However, in this scenario the
scalar particles are too heavy to be produced at the LHC. In addition, if the
scalar mass is much less than O(10^4) TeV, the lifetime of the gluino is too
short to be measured. Therefore, it is hard to probe the scalar particles at a
collider. However, a detailed study of the gluino decay reveals that two body
decay of the gluino carries important information on the scalar scale. In this
paper, we propose a test of this scenario by measuring the decay pattern of the
gluino at the LHC.Comment: 29 pages, 9 figures; version published in JHE
Associations between age and sleep apnea risk among newborn infants
ObjectiveAmong older children, sleep‐disordered breathing (SDB) is associated with measurable neurocognitive consequences. However, diagnostic SDB thresholds are lacking for infants < 12 months. We sought to evaluate the relationship between SDB indices, gestational age (GA), and postmenstrual age (PMA) for infants who underwent clinically‐indicated polysomnograms at a tertiary care center.MethodsEvery infant < 3‐months chronological age whose first clinically‐indicated polysomnogram was between 2/2012 and 2/2017 was included. Linear regression was used to evaluate associations between apnea‐hypopnea index (AHI), obstructive‐apnea index (OAI), and GA and PMA for infants with and without obvious clinical risk factors for SDB (eg, micrognathia and cleft palate).ResultsFor 53 infants without obvious SDB risk factors (GA 35.6 ± 4.5 weeks; PMA 41.2 ± 4.0 weeks), mean AHI was 27 ± 18 and OAI 2.9 ± 4.5. There was a weak inverse relationship between AHI and PMA (r2 = 0.12, P = 0.01), but AHI was not predicted by GA (r2 = 0.04, P = 0.13). Conversely, OAI was more strongly associated with GA (r2 = 0.33, P < 0.0001) than PMA (r2 = 0.08, P = 0.036). For 28 infants with congenital structural anomalies that predispose to SDB (GA 38.0 ± 3.1 weeks, PMA 43.1 ± 3.3 weeks, AHI 37.7 ± 30, OAI 8.2 ± 11.8), neither AHI nor OAI were related to PMA or GA.ConclusionsAmong infants who received clinically‐indicated polysomnograms but did not have obvious structural risk for SDB, AHI declined with advancing PMA, but obstructive‐apnea was best predicted by prematurity. In contrast, the SDB risk did not improve with increasing GA or PMA for infants with congenital structural risk factors; such infants may not outgrow their risk for SDB.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150552/1/ppul24354_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150552/2/ppul24354.pd
The Role of Stochastic Acceleration in the Prompt Emission of Gamma-Ray Bursts: Application to Hadronic Injection
We study effects of particle re-acceleration (or heating) in the post-shock
region via magnetohydrodynamic/plasma turbulence, in the context of a mixed
hadronic-leptonic model for the prompt emission of gamma-ray bursts (GRBs),
using both analytical and numerical methods. We show that stochastically
accelerated (or heated) leptons, which are injected via pp and pg reactions and
subsequent pair cascades, are plausibly able to reproduce the Band function
spectra with alpha~1 and beta~2-3 in the ~MeV range. An additional hard
component coming from the proton-induced cascade emission is simultaneously
expected, which is compatible with observed extra power-law spectra far above
the MeV range. We also discuss the specific implications of hadronic models for
ongoing high-energy neutrino observations.Comment: 12 pages, 8 figures, accepted for publication in ApJ, discussions
added, typos fixed. Results unchange
Synchrotron signature of a relativistic blast wave with decaying microturbulence
Microphysics of weakly magnetized relativistic collisionless shock waves,
corroborated by recent high performance numerical simulations, indicate the
presence of a microturbulent layer of large magnetic field strength behind the
shock front, which must decay beyond some hundreds of skin depths. The present
paper discusses the dynamics of such microturbulence, borrowing from these same
numerical simulations, and calculates the synchrotron signature of a powerlaw
of shock accelerated particles. The decaying microturbulent layer is found to
leave distinct signatures in the spectro-temporal evolution of the spectrum
of a decelerating blast wave, which are
potentially visible in early multi-wavelength follow-up observations of
gamma-ray bursts. This paper also discusses the influence of the evolving
microturbulence on the acceleration process, with particular emphasis on the
maximal energy of synchrotron afterglow photons, which falls in the GeV range
for standard gamma-ray burst parameters. Finally, this paper argues that the
evolving microturbulence plays a key role in shaping the spectra of recently
observed gamma-ray bursts with extended GeV emission, such as GRB090510.Comment: version to appear in MNRAS -- minor modifications + added discussion
of synchrotron self-absorption; 23 pages, 8 figure
Revisiting Frank–Starling: regulatory light chain phosphorylation alters the rate of force redevelopment (ktr) in a length-dependent fashion
Force and power in cardiac muscle have a known dependence on phosphorylation of the myosin-associated regulatory light chain (RLC). We explore the effect of RLC phosphorylation on the ability of cardiac preparations to redevelop force (ktr ) in maximally activating [Ca2+ ]. Activation was achieved by rapidly increasing the temperature (temperature-jump of 0.5-20ºC) of permeabilized trabeculae over a physiological range of sarcomere lengths (1.85-1.94 μm). The trabeculae were subjected to shortening ramps over a range of velocities and the extent of RLC phosphorylation was varied. The latter was achieved using an RLC-exchange technique, which avoids changes in the phosphorylation level of other proteins. The results show that increasing RLC phosphorylation by 50% accelerates ktr by ∼50%, irrespective of the sarcomere length, whereas decreasing phosphorylation by 30% slows ktr by ∼50%, relative to the ktr obtained for in vivo phosphorylation. Clearly, phosphorylation affects the magnitude of ktr following step shortening or ramp shortening. Using a two-state model, we explore the effect of RLC phosphorylation on the kinetics of force development, which proposes that phosphorylation affects the kinetics of both attachment and detachment of cross-bridges. In summary, RLC phosphorylation affects the rate and extent of force redevelopment. These findings were obtained in maximally activated muscle at saturating [Ca2+ ] and are not explained by changes in the Ca2+ -sensitivity of acto-myosin interactions. The length-dependence of the rate of force redevelopment, together with the modulation by the state of RLC phosphorylation, suggests that these effects play a role in the Frank-Starling law of the heart.Published versio
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