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1. chinaXiv:201608.00202 [pdf]

Positive operators of Extended Lorentz cones

S. Z. N?emeth; Guohan Zhang
Subjects: Mathematics >> Control and Optimization.

In this paper necessary conditions and sufficient conditions are given for a linear operator to be a positive operators of an Extended Lorentz cone. Similarities and differences with the positive operators of Lorentz cones are investigated.

submitted time 2016-08-30 Hits3270Downloads1719 Comment 0

2. chinaXiv:201608.00200 [pdf]

Mass hierarchy sensitivity of medium baseline reactor neutrino experiments with multiple detectors

Hongxin Wang; Liang Zhan; Yu-Feng Li; Guofu Cao; Shenjian Chen
Subjects: Physics >> Nuclear Physics

We report the neutrino mass hierarchy (MH) sensitivity of medium baseline reactor neutrino experiments with multiple detectors. Sensitivity of determining the MH can be significantly improved by adding a near detector and combining both the near and far detectors. The size of the sensitivity improvement is related to accuracy of the individual mass-splitting measurements and requires strict control on the relative energy scale uncertainty of the near and far detectors. We study the impact of both baseline and target mass of the near detector on the combined sensitivity. A figure-of-merit is defined to optimize the baseline and target mass of the near detector and the optimal selections are??13~km and??4~kton respectively for a far detector with the 20~kton target mass and 52.5~km baseline. As typical examples of future medium baseline reactor neutrino experiments, the optimal location and target mass of the near detector are selected for JUNO and RENO-50. Finally, we discuss distinct effects of the neutrino spectrum uncertainty for setups of a single detector and double detectors, which indicate that the spectrum uncertainty can be well constrained in the presence of the near detector.

submitted time 2016-08-30 Hits1122Downloads593 Comment 0

3. chinaXiv:201608.00199 [pdf]

Critical Temperature of Chiral Symmetry Restoration for Quark Matter with a Chiral Chemical Potential

M. Ruggieri; G. X. Peng
Subjects: Physics >> Nuclear Physics

In this article we study restoration of chiral symmetry at finite temperature for quark matter with a chiral chemical potential,?μ5, by means of a quark-meson model with vacuum fluctuations included. Vacuum fluctuations give a divergent contribution to the vacuum energy, so the latter has to be renormalized before computing physical quantities. The vacuum term is important for restoration of chiral symmetry at finite temperature and?μ5≠0, therefore we present several plausible renormalization schemes for the ultraviolet divergences at?μ5≠0. Then we compute the critical temperature as a function of?μ5. The main result of our study is that the choice of a renormalization scheme affects the critical temperature; among the three renormalization schemes we investigate, there exists one in which the critical temperature increases with?μ5, a result which has not been found before by chiral model studies and which is in qualitative agreement with recent lattice data as well as with studies based on Schwinger-Dyson equations and universality arguments.

submitted time 2016-08-30 Hits866Downloads469 Comment 0

4. chinaXiv:201608.00198 [pdf]

Tuner control system of spoke012 SRF cavity for C-ADS injector I at IHEP

LIU Na; SUN Yi; WANG Guang-Wei; Zheng MI Zheng-Hui; LIN Hai-Ying; WANG Qun-Yao
Subjects: Physics >> Nuclear Physics

A new tuner control system of spoke superconducting radio frequency (SRF) cavity has been developed and applied to cryomodule I (CM1) of C-ADS injector I at IHEP. We have successfully implemented the tuner controllerfor the first time and achieved a cavity tuning phase error of 0.7degrees (about 4 Hz peak to peak) in the presence of electromechanical coupled resonance. This paper will present the preliminary experimental results based on the new tuner controller under proton beam commissioning.

submitted time 2016-08-30 Hits1038Downloads552 Comment 0

5. chinaXiv:201608.00197 [pdf]

Testing Einstein's Equivalence Principle With Gravitational Waves

Xue-Feng Wu; He Gao; Jun-Jie Wei; Xi-Long Fan; Peter M?esz?aros; Bing Zhang; Zi-Gao Dai; Shuang-Nan Zhang; Zong-Hong Zhu
Subjects: Physics >> Nuclear Physics

A conservative constraint on the Einstein Equivalence Principle (EEP) can be obtained under the assumption that the observed time delay between correlated particles from astronomical sources is dominated by the gravitational fields through which they move. Current limits on the EEP are mainly based on the observed time delays of photons with different energies, and it is highly desirable to develop more accurate tests involving different types of particles. The detection by the advanced LIGO/VIRGO systems of gravitational waves (GWs) will provide attractive candidates for constraining the EEP, which would further extend the tested particle species to the gravitons, with potentially higher accuracy. Considering the capabilities of the advanced LIGO/VIRGO network and the source direction uncertainty, we show that the joint detection of GWs and electromagnetic signals can potentially probe the EEP to an accuracy of 10?11, which is several orders of magnitude tighter than previous limits.

submitted time 2016-08-30 Hits1328Downloads799 Comment 0

6. chinaXiv:201608.00196 [pdf]

Detection of a Possible X-ray Quasi-periodic Oscillation in the Active Galactic Nucleus 1H 0707–495

Hai-Wu Pan; Weimin Yuan; Su Yao; Xin-Lin Zhou; Bifang Liu; Hongyan Zhou & Shuang-Nan Zhang5,1
Subjects: Physics >> Nuclear Physics

Quasi-periodic oscillation (QPO) detected in the X-ray radiation of black hole X-ray binaries (BHXBs) is thought to originate from dynamical processes in the close vicinity of the black holes (BHs), and thus carries important physical information therein. Such a feature is extremely rare in active galactic nuclei (AGNs) with supermassive BHs. Here we report on the detection of a possible X-ray QPO signal with a period of 3800\,s at a confidence level >99.99% in the narrow-line Seyfert 1 galaxy (NLS1) 1H~0707-495 in one data set in 0.2-10\,keV taken with {\it XMM-Newton}. The statistical significance is higher than that of most previously reported QPOs in AGNs. The QPO is highly coherent (quality factor Q=ν/Δν?15) with a high rms fractional variability (?15%). A comprehensive analysis of the optical spectra of this AGN is also performed, yielding a central BH mass 5.2×106M⊙ from the broad emission lines based on the scaling relation. The QPO follows closely the known frequency-BH mass relation, which spans from stellar-mass to supermassive BHs. The absence of the QPO in other observations of the object suggests it a transient phenomenon. We suggest that the (high-frequency) QPOs tend to occur in highly accreting BH systems, from BHXBs to supermassive BHs. Future precise estimation of the BH mass may be used to infer the BH spin from the QPO frequency.

submitted time 2016-08-30 Hits623Downloads359 Comment 0

7. chinaXiv:201608.00195 [pdf]

Study of Higgsstrahlung Cross Section and Higgs Mass Measurement Precisions with ZH ($Z\rightarrow \mu^+\mu^-$) events at CEPC

CHEN Zhen-Xing; YANG Ying; RUAN Man-Qi; WANG Da-Yong; LI Gang; JIN Shan; BAN Yong
Subjects: Physics >> Nuclear Physics

The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. Using Monte Carlo samples of 5 ab?1 at 250 GeV center-of-mass energy, the benchmark luminosity of CEPC Higgs runs, model independent (MI) analyses on Higgsstrahlung (ZH) cross section σZH and Higgs mass mH are performed with ZH events where the Z boson decays into a pair of muons. The relative precision of σZH could reach 0.92\% and the mH could be measured to an accuracy of 6.5 MeV. Using information from Higgs decay final states, the backgrounds could be further reduced, leading to a mass precision of 5.4 MeV. The impacts of tracker size are investigated and parameterized for these measurements. Using similar analysis technology, we analyzed the capability of CEPC in measuring the Higgs invisible decay. Using ZH (Z→μ+μ?) events at 5 ab?1, the upper limit of invisible decay cross section beyond the standard model (SM) σBSMZH,H→inv can be determined to be 2.0 fb at 95\% confidence level.

submitted time 2016-08-30 Hits1100Downloads642 Comment 0

8. chinaXiv:201608.00194 [pdf]

Test flavor SU(3) symmetry in exclusive $\Lambda_c$ decays

Cai-Dian Lu; Wei Wang; Fu-Sheng Yu
Subjects: Physics >> Nuclear Physics

Flavor SU(3) symmetry is a powerful tool to analyze charmed baryon decays, however its applicability remains to be experimentally validated. Since there is not much data on Ξc decays, various exclusive Λc decays especially the ones into a neutron state are essential for the test of flavor symmetry. These decay modes are also helpful to investigate final state interactions in charmed baryon decays. In this work, we discuss the explicit roles of Λc decays into a neutron in testing the flavor symmetry and exploring final state interactions. The involved decay modes include semileptonic decays, two-body and three-body non-leptonic decays, but all of them have not been experimentally observed to date.

submitted time 2016-08-30 Hits1041Downloads616 Comment 0

9. chinaXiv:201608.00193 [pdf]

The laboratory measurement of radioactivity purification for Pb212 in liquid scintillator

Wei Hu; Jian Fang; Bo-Xiang Yu; Xuan Zhang; Li Zhou; Xiao Cai; Li-Jun Sun; Wan-Jin Liu; Lan Wang; Jun-Guang Lu
Subjects: Physics >> Nuclear Physics

The liquid scintillator (LS) has been widely utilized in the past, running and future neutrino experiments, and requirement to the LS radio-purity is higher and higher. The water extraction is a powerful method to remove soluble radioactive nuclei, and a mini-extraction station has been constructed. To evaluate the extraction efficiency and optimize the operation parameters, a setup to load radioactivity to LS and a laboratory scale setup to measure radioactivity which use Bi^{212}-Po^{212}-Pb^{208} cascade decay are developed. Experiences from laboratory study will be useful to large scale water extraction plants design and the optimization of working in future.

submitted time 2016-08-30 Hits1177Downloads679 Comment 0

10. chinaXiv:201608.00192 [pdf]

Constraint on the velocity dependent dark matter annihilation cross section from Fermi-LAT observations of dwarf galaxies

Yi Zhao; Xiao-Jun Bi; Huan-Yu Jia; Peng-Fei Yin; Feng-Rong Zhu
Subjects: Physics >> Nuclear Physics

The gamma-ray observation of dwarf spheroidal satellites (dSphs) is an ideal approach for probing the dark matter (DM) annihilation signature. The latest Fermi-LAT dSph searches have set stringent constraints on the velocity independent annihilation cross section in the small DM mass range, which gives very strong constraints on the scenario to explain the the AMS-02 positron excess by DM annihilation. However, the dSph constraints would change in the velocity dependent annihilation scenarios, because the velocity dispersion in the dSphs varies from that in the Milky Way. In this work, we use a likelihood map method to set constraints on the velocity dependent annihilation cross section from the Fermi-LAT observation of six dSphs. We consider three typical forms of the annihilation cross section, i.e. p-wave annihilation, Sommerfeld enhancement, and Breit-Wigner resonance. For the p-wave annihilation and Sommerfeld-enhancement, the dSph limits would become much weaker and stronger compared with those for the velocity independent annihilation, respectively. For the Breit-Wigner annihilation, the dSph limits would vary depending on the model parameters. We show that the scenario to explain the AMS-02 positron excess by DM annihilation is still viable in the velocity dependent cases

submitted time 2016-08-30 Hits966Downloads574 Comment 0

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