157 research outputs found
Parity and Time Reversal in the Spin-Rotation Interaction
A recently reported discrepancy between experimental and theoretical values
of the muon's g-2 factor is interpreted as due to small violations of the
conservation of P and T in the spin-rotation coupling. The experiments place an
upper limit on these violations and on the weight change of spinning
gyroscopes.Comment: 3 page
Topological doping and the stability of stripe phases
We analyze the properties of a general Ginzburg-Landau free energy with
competing order parameters, long-range interactions, and global constraints
(e.g., a fixed value of a total ``charge'') to address the physics of stripe
phases in underdoped high-Tc and related materials. For a local free energy
limited to quadratic terms of the gradient expansion, only uniform or
phase-separated configurations are thermodynamically stable. ``Stripe'' or
other non-uniform phases can be stabilized by long-range forces, but can only
have non-topological (in-phase) domain walls where the components of the
antiferromagnetic order parameter never change sign, and the periods of charge
and spin density waves coincide. The antiphase domain walls observed
experimentally require physics on an intermediate lengthscale, and they are
absent from a model that involves only long-distance physics. Dense stripe
phases can be stable even in the absence of long-range forces, but domain walls
always attract at large distances, i.e., there is a ubiquitous tendency to
phase separation at small doping. The implications for the phase diagram of
underdoped cuprates are discussed.Comment: 18 two-column pages, 2 figures, revtex+eps
Coulomb Gauge QCD, Confinement, and the Constituent Representation
Quark confinement and the genesis of the constituent quark model are examined
in nonperturbative QCD in Coulomb gauge. We employ a self-consistent method to
construct a quasiparticle basis and to determine the quasiparticle interaction.
The results agree remarkably well with lattice computations. They also
illustrate the mechanism by which confinement and constituent quarks emerge,
provide support for the Gribov-Zwanziger confinement scenario, clarify several
perplexing issues in the constituent quark model, and permit the construction
of an improved model of low energy QCD.Comment: 43 pages, 14 figures, revtex, uses psfig.st
Elastic Scattering of Pions From the Three-nucleon System
We examine the scattering of charged pions from the trinucleon system at a
pion energy of 180 MeV. The motivation for this study is the structure seen in
the experimental angular distribution of back-angle scattering for pi+ 3He and
pi- 3H but for neither pi- 3He nor pi+ 3H. We consider the addition of a double
spin flip term to an optical model treatment and find that, though the
contribution of this term is non-negligible at large angles for pi+ 3He and pi-
3H, it does not reproduce the structure seen in the experiment.Comment: 15 pages + 5 figure
A model independent spin analysis of fundamental particles using azimuthal asymmetries
Exploiting the azimuthal angle dependence of the density matrices we
construct observables that directly measure the spin of a heavy unstable
particle. A novelty of the approach is that the analysis of the azimuthal angle
dependence in a frame other than the usual helicity frame offers an independent
cross-check on the extraction of the spin. Moreover, in some instances when the
transverse polarisation tensor of highest rank is vanishing, for an accidental
or dynamical reason, the standard azimuthal asymmetries vanish and would lead
to a measurement with a wrong spin assignment. In a frame such as the one we
construct, the correct spin assignment would however still be possible. The
method gives direct information about the spin of the particle under
consideration and the same event sample can be used to identify the spins of
each particle in a decay chain. A drawback of the method is that it is
instrumental only when the momenta of the test particle can be reconstructed.
However we hope that it might still be of use in situations with only partial
reconstruction. We also derive the conditions on the production and decay
mechanisms for the spins, and hence the polarisations, to be measured at a
collider experiment. As an example for the use of the method we consider the
simultaneous reconstruction, at the partonic level, of the spin of both the top
and the in top pair production in in the semi-leptonic channel.Comment: 42 pages, 7 figures, 4 table
癌の化学療法に関する研究 特に制癌剤並びに制癌強化剤の担癌生体内代謝に及ぼす影響について
Background: Medication related harm (MRH) is a common cause of morbidity and hospital admission in the elderly, and has significant cost implications for both primary and secondary healthcare resources. The development of risk prediction models has become an increasingly common phenomenon in medicine and can be useful to guide objective clinical decision making, resource allocation and intervention. There are no risk prediction models that are widely used in clinical practice to identify elderly patients at high risk of MRH following hospital<br/>discharge. The aim of this study is to develop a risk prediction model (RPM) to identify elderly patients at high risk of MRH upon discharge from hospital, and to compare this with routine clinical judgment.<br/><br/>Methods/Design: This is a multi-centre, prospective observational study following a cohort of patients for 8 weeks after hospital discharge. Data collection including patient characteristics, medication use, social factors and frailty will take place prior to patient discharge and then the patient will be followed up in the community over the next 8 weeks to determine if they have experienced MRH. Research pharmacists will determine whether patients have<br/>experienced MRH by prospectively reviewing records for unplanned emergency department attendance, hospital readmission and GP consultation related to MRH. Research pharmacists will also telephone patients directly to<br/>determine self-reported MRH, which patients may not have sought further medical attention for. The data collected will inform the development of a RPM which will be externally validated in a follow-up study. <br/><br/>Discussion: There are no RPMs that are used in clinical practice to help stratify elderly patients at high risk of MRH in the community following hospital discharge, despite this being a significant public health problem. This study plans to develop a clinically useful RPM that is better than routine clinical judgment. As this is a multi-centre study<br/>involving clinical settings that serve elderly people of heterogeneous sociodemographic background, it is anticipated that this RPM will be generalizable
Quantum Fluctuation Relations for the Lindblad Master Equation
An open quantum system interacting with its environment can be modeled under
suitable assumptions as a Markov process, described by a Lindblad master
equation. In this work, we derive a general set of fluctuation relations for
systems governed by a Lindblad equation. These identities provide quantum
versions of Jarzynski-Hatano-Sasa and Crooks relations. In the linear response
regime, these fluctuation relations yield a fluctuation-dissipation theorem
(FDT) valid for a stationary state arbitrarily far from equilibrium. For a
closed system, this FDT reduces to the celebrated Callen-Welton-Kubo formula
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
Microstate Dependence of Scattering from the D1-D5 System
We investigate the question of distinguishing between different microstates
of the D1-D5 system (with charges Q_1 and Q_5), by scattering with an
incoherent beam, composed of a supergravity probe, with central energy E_0 and
width (\Delta E). The scattering is studied in the dual CFT description in the
orbifold limit for finite R, where R is the radius of the circle on which the
D1 branes are wrapped. When R(\Delta E) >> 1, the absorption cross-section is
found to be independent of the microstate and identical to the leading
semiclassical answer computed from the naive geometry. For smaller (\Delta E),
the answer depends on the particular microstate, which we examine for both
typical and atypical microstates. We derive an upper bound for the leading
correction to the cross-section when 1/R >> \Delta E >> (the average energy gap
1/{R [sqrt(Q_1Q_5)]}. For a typical state the bound is proportional to the area
of the stretched horizon, [\sqrt(Q_1 Q_5)], up to [log (Q_1Q_5)] terms.
Furthermore, when E_0 << (\Delta E), the proportionality constant is a pure
number independent of all energy scales. Numerical calculations using
Lorentzian profiles show that the actual value of the correction is in fact
proportional to [sqrt(Q_1Q_5)] without the logarithmic factor. We offer some
speculations about how this result can be consistent with a resolution of the
naive geometry by higher derivative corrections to supergravity.Comment: 42 pages, 5 figure
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
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