196 research outputs found
Rigid supersymmetry with boundaries
We construct rigidly supersymmetric bulk-plus-boundary actions, both in
-space and in superspace. For each standard supersymmetric bulk action a
minimal supersymmetric bulk-plus-boundary action follows from an extended -
or -term formula. Additional separately supersymmetric boundary actions can
be systematically constructed using co-dimension one multiplets (boundary
superfields). We also discuss the orbit of boundary conditions which follow
from the Euler-Lagrange variational principle.Comment: 28 pages, JHEP clas
On the equivalence between real and superfield 5d formalisms
We explicitly prove the equivalence and construct a dictionary between two
different supersymmetric formalisms for five-dimensional theories commonly used
in the literature. One is the real formalism, which consists in doubling the
number of degrees of freedom and then imposing reality constraints and the
other is the usual superfield formalism.Comment: 19 page
Quantum aspects of a noncommutative supersymmetric kink
We consider quantum corrections to a kink of noncommutative supersymmetric
phi^4 theory in 1+1 dimensions. Despite the presence of an infinite number of
time derivatives in the action, we are able to define supercharges and a
Hamiltonian by using an unconventional canonical formalism. We calculate the
quantum energy E of the kink (defined as a half-sum of the eigenfrequencies of
fluctuations) which coincides with its' value in corresponding commutative
theory independently of the noncommutativity parameter. The renormalization
also proceeds precisely as in the commutative case. The vacuum expectation
value of the new Hamiltonian is also calculated and appears to be consistent
with the value of the quantum energy E of the kink.Comment: 20 pages, v2: a reference adde
Tensor calculus for supergravity on a manifold with boundary
Using the simple setting of 3D N=1 supergravity, we show how the tensor
calculus of supergravity can be extended to manifolds with boundary. We present
an extension of the standard F-density formula which yields supersymmetric
bulk-plus-boundary actions. To construct additional separately supersymmetric
boundary actions, we decompose bulk supergravity and bulk matter multiplets
into co-dimension one submultiplets. As an illustration we obtain the
supersymmetric extension of the York-Gibbons-Hawking extrinsic curvature
boundary term. We emphasize that our construction does not require any boundary
conditions on off-shell fields. This gives a significant improvement over the
existing orbifold supergravity tensor calculus.Comment: 20 pages, JHEP format; published versio
The check of QCD based on the tau-decay data analysis in the complex q^2-plane
The thorough analysis of the ALEPH data on hadronic tau-decay is performed in
the framework of QCD. The perturbative calculations are performed in 3 and
4-loop approximations. The terms of the operator product expansion (OPE) are
accounted up to dimension D=8. The value of the QCD coupling constant
alpha_s(m_tau^2)=0.355 pm 0.025 was found from hadronic branching ratio R_tau.
The V+A and V spectral function are analyzed using analytical properties of
polarization operators in the whole complex q^2-plane. Borel sum rules in the
complex q^2 plane along the rays, starting from the origin, are used. It was
demonstrated that QCD with OPE terms is in agreement with the data for the
coupling constant close to the lower error edge alpha_s(m_tau^2)=0.330. The
restriction on the value of the gluonic condensate was found
=0.006 pm 0.012 GeV^2. The analytical perturbative QCD was
compared with the data. It is demonstrated to be in strong contradiction with
experiment. The restrictions on the renormalon contribution were found. The
instanton contributions to the polarization operator are analyzed in various
sum rules. In Borel transformation they appear to be small, but not in spectral
moments sum rules.Comment: 24 pages; 1 latex + 13 figure files. V2: misprints are corrected,
uncertainty in alpha_s is explained in more transparent way, acknowledgement
is adde
Muon capture by 3He nuclei followed by proton and deuteron production
The paper describes an experiment aimed at studying muon capture by
nuclei in pure and mixtures at various densities. Energy distributions of
protons and deuterons produced via and are measured for the
energy intervals MeV and MeV, respectively. Muon capture
rates, and are obtained using two different analysis methods. The
least--squares methods gives , . The Bayes theorem
gives ,
. The experimental
differential capture rates, and , are compared with theoretical
calculations performed using the plane--wave impulse approximation (PWIA) with
the realistic NN interaction Bonn B potential. Extrapolation to the full energy
range yields total proton and deuteron capture rates in good agreement with
former results.Comment: 17 pages, 13 figures, accepted for publication in PR
Is X(3872) {\sl Really} a Molecular State?
After taking into account both the pion and sigma meson exchange potential,
we have performed a dynamical calculation of the system.
The meson exchange potential is repulsive from heavy quark symmetry
and numerically important for a loosely bound system. Our analysis disfavors
the interpretation of X(3872) as a loosely bound molecular state if we use the
experimental coupling constant and a reasonable cutoff
around 1 GeV, which is the typical hadronic scale. Bound state solutions with
negative eigenvalues for the system exist only with either a
very large coupling constant (two times of the experimental value) or a large
cutoff ( GeV or GeV). In contrast, there
probably exists a loosely bound S-wave molecular state. Once
produced, such a molecular state would be rather stable since its dominant
decay mode is the radiative decay through . Experimental
search of these states will be very interesting.Comment: 11 pages, 7 figures, 9 tables. The version to appear in EPJ
Magnetic resonance imaging on sodium nuclei: potential medical applications of 23Na MRI
Sodium is a key element in a living organism. The increase of its concentration is an indicator of many pathological conditions. 23Na magnetic resonance imaging (MRI) is a quantitative method that allows to determine the sodium content in tissues and organs in vivo. This method has not yet entered clinical practice widely, but it has already been used as a clinical research tool to investigate diseases such as brain tumors, breast cancer, stroke, multiple sclerosis, hypertension, diabetes, ischemic heart disease, osteoarthritis. The active development of the 23Na MRI is promoted by the growth of available magnetic elds, the expansion of hardware capabilities, and the development of pulse sequences with ultra-short echo time
Measurement of the cross section and limits on anomalous triple gauge couplings in collisions at = 1.96 TeV
We present a new measurement of the () cross section and limits on anomalous triple gauge couplings. Using 4.1
fb of integrated luminosity of collisions at TeV, we observe 34 candidate events with an estimated background of
events. We measure the production cross section to be
pb, in good agreement with the standard model
prediction. We find no evidence for anomalous couplings and set 95% C.L.
limits on the coupling parameters, and , in the HISZ parameterization for a TeV
form factor scale. These are the best limits to date obtained from the direct
measurement of the vertex.Comment: 8 pages, 7 figures, 2 table
Measurement of the View the tt production cross-section using eÎŒ events with b-tagged jets in pp collisions at âs = 13 TeV with the ATLAS detector
This paper describes a measurement of the inclusive top quark pair production cross-section (ÏttÂŻ) with a data sample of 3.2 fbâ1 of protonâproton collisions at a centre-of-mass energy of âs = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electronâmuon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously ÏttÂŻ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be:
ÏttÂŻ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb,
where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented
- âŠ