170 research outputs found
Observing dynamical supersymmetry breaking with euclidean lattice simulations
A strict positivity of the ground-state energy is a necessary and sufficient
condition for spontaneous supersymmetry breaking. This ground-state energy may
be directly determined from the expectation value of the Hamiltonian in the
functional integral, defined with an \emph{antiperiodic} temporal boundary
condition for all fermionic variables. We propose to use this fact to observe
the dynamical spontaneous supersymmetry breaking in Euclidean lattice
simulations. If a lattice formulation possesses a manifestly preserved
fermionic symmetry, there exists a natural choice of a Hamiltonian operator
that is consistent with a topological nature of the Witten index. We
numerically confirm the validity of our idea in models of supersymmetric
quantum mechanics. We further examine the possibility of dynamical
supersymmetry breaking in the two-dimensional super
Yang-Mills theory with the gauge group SU(2), for which the Witten index is
unknown. Although statistical errors are still large, we do not observe
positive ground-state energy, at least within one standard deviation. This
prompts us to draw a different conclusion from a recent conjectural claim that
supersymmetry is dynamically broken in this system.Comment: 35 pages, 9 figures, the final version to appear in Prog. Theor. Phy
The utilization of YAP Scintillation Detector for Soft Gamma Radiation Measurement in Backscatter Thickness Gauge
ABSTRACT Interesting properties of a YAP(Ce) scintillator make it an alternative solution for low energy gamma measurement in high counting rates that previously employed GM counter tubes and/or Nal(Tl) scintillators. Some characteristics of the YAP(Ce) crystal combined with a photomultiplier tube have been successfully demonstrated in a backscatter mode of thickness gauging with 241Am gamma-source.
SUSY WT identity in a lattice formulation of 2D SYM
We address some issues relating to a supersymmetric (SUSY) Ward-Takahashi
(WT) identity in Sugino's lattice formulation of two-dimensional (2D)
supersymmetric Yang-Mills theory (SYM). A
perturbative argument shows that the SUSY WT identity in the continuum theory
is reproduced in the continuum limit without any operator
renormalization/mixing and tuning of lattice parameters. As application of the
lattice SUSY WT identity, we show that a prescription for the hamiltonian
density in this lattice formulation, proposed by Kanamori, Sugino and Suzuki,
is justified also from a perspective of an operator algebra among
correctly-normalized supercurrents. We explicitly confirm the SUSY WT identity
in the continuum limit to the first nontrivial order in a semi-perturbative
expansion.Comment: 15 pages, uses elsart.cls, the final version to appear in Phys. Lett.
Restoration of supersymmetry on the lattice: Two-dimensional supersymmetric Yang-Mills theory
By numerically investigating the conservation law of the supercurrent, we
confirm the restoration of supersymmetry in Sugino's lattice formulation of the
two-dimensional supersymmetric SU(2) Yang-Mills theory with
a scalar mass term. Subtlety in the case without the scalar mass term, that
appears to ruin perturbative power counting, is also pointed out.Comment: 24 pages, 10 figures, uses elsart.cls, the final version to appear in
Nucl. Phys.
Two-dimensional N=(2,2) super Yang-Mills theory on computer
We carry out preliminary numerical study of Sugino's lattice formulation
\cite{Sugino:2004qd,Sugino:2004qdf} of the two-dimensional
super Yang-Mills theory (2d SYM) with the gauge group
\SU(2). The effect of dynamical fermions is included by re-weighting a
quenched ensemble by the pfaffian factor. It appears that the complex phase of
the pfaffian due to lattice artifacts and flat directions of the classical
potential are not problematic in Monte Carlo simulation. Various one-point
supersymmetric Ward-Takahashi (WT) identities are examined for lattice spacings
up to with the fixed physical lattice size , where
denotes the gauge coupling constant in two dimensions. WT identities implied by
an exact fermionic symmetry of the formulation are confirmed in fair accuracy
and, for most of these identities, the quantum effect of dynamical fermions is
clearly observed. For WT identities expected only in the continuum limit, the
results seem to be consistent with the behavior expected from supersymmetry,
although we do not see clear distintion from the quenched simulation. We
measure also the expectation values of renormalized gauge-invariant bi-linear
operators of scalar fields.Comment: 24 pages, 10 figures, the distribution of the complex phase of the
pffafian is also measured, the final version to appear in JHE
Effect of forced-air warming by an underbody blanket on end-of-surgery hypothermia: a propensity score-matched analysis of 5063 patients
Abstract Background Underbody blankets have recently been launched and are used by anesthesiologists for surgical patients. However, the forced-air warming effect of underbody blankets is still controversial. The aim of this study was to determine the effect of forced-air warming by an underbody blanket on body temperature in anesthetized patients. Methods We retrospectively analyzed 5063 surgical patients. We used propensity score matching to reduce the bias caused by a lack of randomization. After propensity score matching, the change in body temperature from before to after surgery was compared between patients who used underbody blankets (Under group) and those who used other types of warming blankets (Control group). The incidence of hypothermia (i.e., body temperature < 36.0 °C at the end of surgery) was compared between the two groups. A p value < 0.05 was considered to indicate statistical significance. Results We obtained 489 propensity score-matched pairs of patients from the two groups, of whom 33 and 63 had hypothermia in the Under and Control groups, respectively (odds ratio: 0.49, 95% confidence interval: 0.31–0.76, p = 0.0013). Conclusions The present study suggests that the underbody blanket may help reduce the incidence of intraoperative hypothermia and may be more efficient in warming anesthetized patients compared with other types of warming blankets. Trial registration UMIN Clinical Trials Registry (Identifier: UMIN000022909; retrospectively registered on June 27, 2016)
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