575 research outputs found
A Quantum Check of Non-Supersymmetric AdS/dCFT
Via a challenging field-theory computation, we confirm a supergravity
prediction for the non-supersymmetric D3-D7 probe-brane system with probe
geometry AdS_4 x S^2 x S^2, stabilized by fluxes. Supergravity predicts, in a
certain double-scaling limit, the value of the one-point functions of chiral
primaries of the dual defect version of N=4 SYM theory, where the fluxes
translate into SO(3) x SO(3)-symmetric, Lie-algebra-valued vacuum expectation
values for all six scalar fields. Using a generalization of the technique based
on fuzzy spherical harmonics developed for the related D3-D5 probe-brane
system, we diagonalize the resulting mass matrix of the field theory.
Subsequently, we calculate the planar one-loop correction to the vacuum
expectation values of the scalars in dimensional reduction and find that it is
UV finite and non-vanishing. We then proceed to calculating the one-loop
correction to the planar one-point function of any single-trace scalar operator
and explicitly evaluate this correction for a 1/2-BPS operator of length L at
two leading orders in the double-scaling limit, finding exact agreement with
the supergravity prediction.Comment: 33+14 pages, 5 figures; v2: typos corrected, reference added, version
published in JHE
Bootstrapping Coulomb and Higgs branch operators
We apply the numerical conformal bootstrap to correlators of Coulomb and
Higgs branch operators in superconformal theories. We
start by revisiting previous results on single correlators of Coulomb branch
operators. In particular, we present improved bounds on OPE coefficients for
some selected Argyres-Douglas models, and compare them to recent work where the
same cofficients were obtained in the limit of large charge. There is solid
agreement between all the approaches. The improved bounds can be used to
extract an approximate spectrum of the Argyres-Douglas models, which can then
be used as a guide in order to corner these theories to numerical islands in
the space of conformal dimensions. When there is a flavor symmetry present, we
complement the analysis by including mixed correlators of Coulomb branch
operators and the moment map, a Higgs branch operator which sits in the same
multiplet as the flavor current. After calculating the relevant superconformal
blocks we apply the numerical machinery to the mixed system. We put general
constraints on CFT data appearing in the new channels, with particular emphasis
on the simplest Argyres-Douglas model with non-trivial flavor symmetry.Comment: 45 pages, 11 figures, minor changes in v
Defect two-point functions in 6d (2,0) theories
We consider correlation functions in 6d theories of two
-BPS operators inserted away from a -BPS surface
defect. In the large central charge limit the leading connected contribution
corresponds to sums of tree-level Witten diagram in AdSS in the
presence of an AdS defect. We show that these correlators can be uniquely
determined by imposing only superconformal symmetry and consistency conditions,
eschewing the details of the complicated effective Lagrangian. We explicitly
compute all such two-point functions. The result exhibits remarkable hidden
simplicity.Comment: 7 pages, 1 figure, 1 table, 1 ancillary Mathematica noteboo
Scale without Conformal Invariance in Dipolar Ferromagnets
We revisit critical phenomena in ferromagnets with strong dipolar
interactions. The corresponding RG fixed point - dipolar fixed point - was
first studied in 1973 by Aharony and Fisher. It is distinct from the Heisenberg
fixed point, although the critical exponents are close. On the theoretical
side, we discuss scale invariance without conformal invariance realized by this
fixed point. We elucidate the non-renormalization of the virial current due to
a shift symmetry, and show that the same mechanism is at work in all other
known local fixed points which are scale but not conformal invariant. On the
phenomenological side, we discuss the relative strength of dipolar and
short-range interactions. In some materials, like the europium compounds,
dipolar interactions are strong, and the critical behavior is dipolar. In
others, like Fe or Ni, dipolar interactions are weaker, and the Heisenberg
critical behavior in a range of temperatures is followed by the dipolar
behavior closer to the critical point. Some of these effects have been seen
experimentally.Comment: 28 pages + 15 pages appendix, 2 figure
Bootstrapping line defects with global symmetry
We use the numerical bootstrap to study conformal line defects with
global symmetry. Our results are very general and capture in particular
conformal line defects originating from bulk CFTs with a continuous global
symmetry, which can either be preserved or partially broken by the presence of
the defect. We begin with an agnostic approach and perform a systematic
bootstrap study of correlation functions between two canonical operators on the
defect: the displacement and the tilt. We then focus on two interesting
theories: a monodromy line defect and a localized magnetic field line defect.
To this end, we combine the numerical bootstrap with the
-expansion, where we complement existing results in the literature
with additional calculations. For the monodromy defect our numerical results
are consistent with expectations, with known analytic solutions sitting inside
our numerical bounds. For the localized magnetic field line defect our plots
show a series of intriguing cusps which we explore.Comment: 54 pages, 11 figure
開目抄鑚仰(一) 科段正誤表
We consider a non-supersymmetric domain-wall version of SYM
theory where five out of the six scalar fields have non-zero classical values
on one side of a wall of codimension one. The classical fields have commutators
which constitute an irreducible representation of the Lie algebra
leading to a highly non-trivial mixing between color and
flavor components of the quantum fields. Making use of fuzzy spherical
harmonics on , we explicitly solve the mixing problem and derive not only
the spectrum of excitations at the quantum level but also the propagators of
the original fields needed for perturbative quantum computations. As an
application, we derive the one-loop one-point function of a chiral primary and
find complete agreement with a supergravity prediction of the same quantity in
a double-scaling limit which involves a limit of large instanton number in the
dual D3-D7 probe-brane setup.Comment: 37 pages, 1 figur
MM, SARS-CoV-2 infection, and inpatient mortality
There is limited information on the characteristics, pre-admission prognostic factors, and outcomes of patients with multiple myeloma (MM) hospitalized with coronavirus disease 2019 (COVID-19). This retrospective case series investigated characteristics and outcomes of 167 MM patients hospitalized with COVID-19 reported from 73 hospitals within the Spanish Myeloma Collaborative Group network in Spain between March 1 and April 30, 2020. Outcomes were compared with a randomly selected contemporary cohort of 167 age-/sex-matched non-cancer patients with COVID-19 admitted at 6 participating hospitals. Common demographic, clinical, laboratory, treatment, and outcome variables were collected; specific disease status and treatment data were collected for MM patients. Among the MM and non-cancer patients, median age was 71 years and 57% of patients were male in each series, and 75% and 77% of patients, respectively, had at least one comorbidity. COVID-19 clinical severity was moderate-severe in 77% and 89% of patients and critical in 8% and 4%, respectively. Supplemental oxygen was required by 47% and 55% of MM and non-cancer patients, respectively, and 21%/9% vs 8%/6% required non-invasive/invasive ventilation. Inpatient mortality was 34% and 23% in MM and non-cancer patients, respectively. Among MM patients, inpatient mortality was 41% in males, 42% in patients aged >65 years, 49% in patients with active/progressive MM at hospitalization, and 59% in patients with comorbid renal disease at hospitalization, which were independent prognostic factors of inpatient mortality on adjusted multivariate analysis. This case series demonstrates the increased risk and identifies predictors of inpatient mortality among MM patients hospitalized with COVID-19.This study was supported by PETHEMA FoundationN
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV
The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration
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