arXiv subjects

J. Jang

Publications and source records attributed to J. Jang.

26 records · Page 2Linked to original sources

arXiv2012

Comment on "Quantum oscillations in nanofabricated rings of spin-triplet superconductor Sr2RuO4"

Recently Jang et al. reported the observation of half-height magnetization steps in cantilever magnetometry measurements of mesoscopic annular Sr2RuO4 particles. Such magnetization features were interpreted as the presence of half-quantum vortices. In an attempt to examine our findings, very recently Cai et al. (1202.3146) have performed magnetotransport measurements of micron-size rings fabricated from small Sr2RuO4 crystals. While fabrication of such samples and subsequent verification of our findings is highly desirable, we would like to point out that, at the current state of affairs, the direct comparison is incomplete partly due to the fact that the measurements of Cai et al. were lacking an important ingredient -- the in-plane magnetic field. We would also like to offer clarification on few questionable statements made by the authors of 1202.3146.

cond-mat.supr-con↗

arXiv2011

Observation of half-height magnetization steps in Sr2RuO4

Spin-triplet superfluids can support exotic objects, such as half-quantum vortices characterized by the nontrivial winding of the spin structure. We present cantilever magnetometry measurements performed on mesoscopic samples of Sr2RuO4, a spin-triplet superconductor. For micron-sized annular-shaped samples, we observe transitions between integer fluxoid states, as well as a regime characterized by "half-integer transitions," i.e., steps in the magnetization with half the height of the ones we observe between integer fluxoid states. These half-height steps are consistent with the existence of half-quantum vortices in superconducting Sr2RuO4.

cond-mat.supr-con↗

arXiv2009

Test Measurements of Prototype Counters for CLAS12 Central Time-of-Flight System using 45 MeV protons

A comparative measurement of timing properties of magnetic-resistant fine mesh R7761-70 and ordinary fast R2083 photomultipliers is presented together with preliminary results on the operation of R7761-70 PMs in magnetic field up to 1100 Gauss. The results were obtained using the proton beam of the MC50 Cyclotron of Korea Institute of Radilogical and Medical Sciences. The ratio of the effective R7761-70 and R2083 TOF (or timing) resolutions was extracted by using two different methods. The results are $1.05\pm 0.066$ and $1.07\pm 0.062$. The gain of R7761-70 PMs is not affected by magnetic field. The R7761-70 TOF/timing resolution becomes $\sim 8%$ better at 1100 Gauss if the external field is oriented parallel to the PM axis. The results prove the advantages of the design of the CLAS12 Central Time-of-flight system with fine-mesh photomultipliers in comparison with the "conservative" design based on ordinary R2083 PMs and long bent light guides.

physics.ins-det↗

arXiv2008

Evidence for a narrow N(1685) resonance in eta photoproduction off the nucleon

Revised analysis of Sigma beam asymmetry for eta photoproduction off the free proton from GRAAL is presented. New analysis reveals a narrow structure near W ~1.685 GeV. We describe this structure by the contribution of a narrow resonance with quantum numbers P_{11}, or P_{13}, or D_{13}. Being considered together with the recent observations of a bump-like structure at W~1.68 GeV in the quasi-free eta photoproduction off the neutron, this result provides an evidence for a narrow (Gamma < 25 MeV) N*(1685) resonance. Properties of this possible new nucleon state, namely the mass, the narrow width, and the much stronger photocoupling to the neutron, are similar to those predicted for the non-strange member of anti-decouplet of exotic baryons.

hep-ex↗

arXiv2008

Photoproduction off the nucleon revisited: Evidence for a narrow N(1688) resonance?

Revised analysis of $Σ$ beam asymmetry for the $η$ photoproduction on the free proton reveals a structure at $W\sim 1.69$ GeV. Fit of the experimental data based on the E429 solution of the SAID partial wave analysis suggests a narrow ($Γ\leq 25$ MeV) resonance. Possible candidates are $P_{11}, P_{13}$, or $D_{13}$ resonances. The result is considered in conjunction with the recent evidence for a bump-like structure at $W\sim 1.67 - 1.68$ GeV in the quasi-free $η$ photoproduction on the neutron.

hep-ex↗

arXiv2007

Eta Photoproduction on the proton revisited: Evidence for a narrow N(1685) resonance

Revised analysis of $Σ$ beam asymmetry for $η$ photoproduction on the free proton reveals a resonant structure at $W\sim 1.69$ GeV. Comparison of experimental data with multipole decomposition based on the E429 solution of the SAID partial wave analysis and including narrow states, suggests a narrow ($Γ\leq 15$ MeV) resonance. Possible candidates are $P_{11}$, $P_{13}$, or $D_{13}$ resonances. The result is considered in conjunction with the recent evidence for a bump-like structure at $W\sim 1.67 - 1.68$ GeV in quasi-free $η$ photoproduction on the neutron.

hep-ex↗

arXiv2007

Evidence for a narrow structure at W~1.68 GeV in eta photoproduction on the neutron

New results on quasi-free $η$ photoproduction on the neutron and proton bound in a deuteron target are presented. The $γn \to ηn$ quasi-free cross section reveals a bump-like structure which is not seen in the cross section on the proton. This structure may signal the existence of a relatively narrow ($M\sim 1.68$ GeV, $Γ\leq 30$ MeV) baryon state.

hep-ex↗

arXiv2002

Compression and diffusion: a joint approach to detect complexity

The adoption of the Kolmogorov-Sinai (KS) entropy is becoming a popular research tool among physicists, especially when applied to a dynamical system fitting the conditions of validity of the Pesin theorem. The study of time series that are a manifestation of system dynamics whose rules are either unknown or too complex for a mathematical treatment, is still a challenge since the KS entropy is not computable, in general, in that case. Here we present a plan of action based on the joint action of two procedures, both related to the KS entropy, but compatible with computer implementation through fast and efficient programs. The former procedure, called Compression Algorithm Sensitive To Regularity (CASToRe), establishes the amount of order by the numerical evaluation of algorithmic compressibility. The latter, called Complex Analysis of Sequences via Scaling AND Randomness Assessment (CASSANDRA), establishes the complexity degree through the numerical evaluation of the strength of an anomalous effect. This is the departure, of the diffusion process generated by the observed fluctuations, from ordinary Brownian motion. The CASSANDRA algorithm shares with CASToRe a connection with the Kolmogorov complexity. This makes both algorithms especially suitable to study the transition from dynamics to thermodynamics, and the case of non-stationary time series as well. The benefit of the joint action of these two methods is proven by the analysis of artificial sequences with the same main properties as the real time series to which the joint use of these two methods will be applied in future research work.

cond-mat↗