Showing papers in "Chinese Physics C in 2017"
TL;DR: The second part of the new evaluation of atomic masses, AME2020, is described in Part I as discussed by the authors using least-squares adjustments to all evaluated and accepted experimental data.
Abstract: This is the second part of the new evaluation of atomic masses, AME2020. Using least-squares adjustments to all evaluated and accepted experimental data, described in Part I, we derived tables with numerical values and graphs which supersede those given in AME2016. The first table presents the recommended atomic mass values and their uncertainties. It is followed by a table of the influences of data on primary nuclides, a table of various reaction and decay energies, and finally, a series of graphs of separation and decay energies. The last section of this paper provides all input data references that were used in the AME2020 and the NUBASE2020 evaluations.
1,248 citations
TL;DR: The NUBASE2016 evaluation as mentioned in this paper contains the recommended values for nuclear and decay properties of 3437 nuclides in their ground and excited isomeric (T(1/2)≥ 100 n) states.
Abstract: This paper presents the NUBASE2016 evaluation that contains the recommended values for nuclear and decay properties of 3437 nuclides in their ground and excited isomeric (T(1/2) ≥ 100 ns) states. All nuclides for which any experimental information is known were considered. NUBASE2016 covers all data published by October 2016 in primary (journal articles) and secondary (mainly laboratory reports and conference proceedings) references, together with the corresponding bibliographical information. During the development of NUBASE2016, the data available in the 'Evaluated Nuclear Structure Data File' (ENSDF) database were consulted and critically assessed for their validity and completeness. Furthermore, a large amount of new data and some older experimental results that were missing from ENSDF were compiled, evaluated and included in NUBASE2016. The atomic mass values were taken from the 'Atomic Mass Evaluation' (AME2016, second and third parts of the present issue). In cases where no experimental data were available for a particular nuclide, trends in the behavior of specific properties in neighboring nuclides (TNN) were examined. This approach allowed to estimate values for a range of properties that are labeled in NUBASE2016 as 'non-experimental' (flagged '#'). Evaluation procedures and policies used during the development of this database are presented, together with a detailed table of recommended values and their uncertainties. AMDC: http://amdc.impcas.ac.cn/ Contents The NUBASE2016 evaluation of nuclear propertiesAcrobat PDF (1.1 MB) Table I. The NUBASE2016 table of nuclear and decay propertiesAcrobat PDF (706 KB)
513 citations
TL;DR: In this article, the first two articles (Part I and Part II) describe the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction, decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties.
Abstract: This is the first of two articles (Part I and Part II) that presents the results of the new atomic mass evaluation, AME2020. It includes complete information on the experimental input data that were used to derive the tables of recommended values which are given in Part II. This article describes the evaluation philosophy and procedures that were implemented in the selection of specific nuclear reaction, decay and mass-spectrometric data which were used in a least-squares fit adjustment in order to determine the recommended mass values and their uncertainties. All input data, including both the accepted and rejected ones, are tabulated and compared with the adjusted values obtained from the least-squares fit analysis. Differences with the previous AME2016 evaluation are discussed and specific examples are presented for several nuclides that may be of interest to AME users.
419 citations
TL;DR: A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported in this article, where an excess of events in the region of 4−6 MeV was found in the measured spectrum, with a local significance of 4.4σ.
Abstract: A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GWth nuclear reactors and detected by eight antineutrino detectors deployed in two near (560 m and 600 m flux-weighted baselines) and one far (1640 m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946±0.020 (0.992±0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4–6 MeV was found in the measured spectrum, with a local significance of 4.4σ. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.
130 citations
TL;DR: Koch et al. as mentioned in this paper examined the current theoretical and experimental status of the chiral magnetic effect and discussed possible future strategies for resolving uncertainties in interpretation including recommendations for theoretical work, recommendations for measurements based on data collected in the past five years, and recommendations for beam use in the coming years of RHIC.
Abstract: Author(s): Koch, V; Schlichting, S; Skokov, V; Sorensen, P; Thomas, J; Voloshin, S; Wang, G; Yee, HU | Abstract: In this review, we examine the current theoretical and experimental status of the chiral magnetic effect. We discuss possible future strategies for resolving uncertainties in interpretation including recommendations for theoretical work, recommendations for measurements based on data collected in the past five years, and recommendations for beam use in the coming years of RHIC. We specifically investigate the case for colliding nuclear isobars (nuclei with the same mass but different charge) and find the case compelling. We recommend that a program of nuclear isobar collisions to isolate the chiral magnetic effect from background sources be placed as a high priority item in the strategy for completing the RHIC mission.
127 citations
TL;DR: In this paper, a general study of Higgs exotic decays at future e(+)e(-) lepton colliders was performed, focusing on the Higgs decays with hadronic final states and missing energy.
Abstract: The discovery of unexpected properties of the Higgs boson would offer an intriguing opportunity to shed light on some of the most profound puzzles in particle physics. Beyond Standard Model (BSM) decays of the Higgs boson could reveal new physics in a direct manner. Future electron-positron lepton colliders operating as Higgs factories, including CEPC, FCC-ee and ILC, with the advantages of a clean collider environment and large statistics, could greatly enhance sensitivity in searching for these BSM decays. In this work, we perform a general study of Higgs exotic decays at future e(+)e(-) lepton colliders, focusing on the Higgs decays with hadronic final states and/or missing energy, which are very challenging for the High-Luminosity program of the Large Hadron Collider (HL-LHC). We show that with simple selection cuts, (10(-3)-10(-5)) limits on the Higgs exotic decay branching fractions can be achieved using the leptonic decaying spectator Z boson in the associated production mode e(+)e(-)→ ZH. We further discuss the interplay between detector performance and Higgs exotic decays, and other possibilities of exotic decays. Our work is a first step in a comprehensive study of Higgs exotic decays at future lepton colliders, which is a key area of Higgs physics that deserves further investigation.
100 citations
TL;DR: Anomalous Viscous Fluid Dynamics (AVFD) was proposed in this paper, which computes the evolution of fermion currents on top of realistic bulk evolution in heavy ion collisions and simultaneously accounts for both anomalous and normal viscous transport effects.
Abstract: The Chiral Magnetic Effect (CME) is a macroscopic manifestation of fundamental chiral anomaly in a many-body system of chiral fermions, and emerges as an anomalous transport current in the fluid dynamics framework. Experimental observation of the CME is of great interest and has been reported in Dirac and Weyl semimetals. Significant efforts have also been made to look for the CME in heavy ion collisions. Critically needed for such a search is the theoretical prediction for the CME signal. In this paper we report a first quantitative modeling framework, Anomalous Viscous Fluid Dynamics (AVFD), which computes the evolution of fermion currents on top of realistic bulk evolution in heavy ion collisions and simultaneously accounts for both anomalous and normal viscous transport effects. AVFD allows a quantitative understanding of the generation and evolution of CME-induced charge separation during the hydrodynamic stage, as well as its dependence on theoretical ingredients. With reasonable estimates of key parameters, the AVFD simulations provide the first phenomenologically successful explanation of the measured signal in 200 AGeV AuAu collisions.
95 citations
TL;DR: In this paper, a new class of solutions to the Einstein field equations for an anisotropic matter distribution in which the interior space-time obeys the Karmarkar condition is presented.
Abstract: We present a new class of solutions to the Einstein field equations for an anisotropic matter distribution in which the interior space-time obeys the Karmarkar condition. The necessary and sufficient condition required for a spherically symmetric space-time to be of Class One reduces the gravitational behavior of the model to a single metric function. By assuming a physically viable form for the g(rr) metric potential we obtain an exact solution of the Einstein field equations which is free from any singularities and satisfies all the physical criteria. We use this solution to predict the masses and radii of well-known compact objects such as Cen X-3, PSR J0348+0432, PSR B0943+10 and XTE J1739-285.
81 citations
Ohio State University1, Tsinghua University2, Shandong University3, Nankai University4, East China University of Science and Technology5, University of Maryland, College Park6, Charles University in Prague7, Sun Yat-sen University8, Fujian University of Technology9, China Iron and Steel Research Institute Group10, Brookhaven National Laboratory11, Chinese Academy of Sciences12, Wuhan University13, Dresden University of Technology14
TL;DR: The China Jinping Underground Laboratory (CJPL) has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory in the world.
Abstract: The China Jinping Underground Laboratory (CJPL), which has the lowest cosmic-ray muon flux and the lowest reactor neutrino flux of any laboratory, is ideal to carry out low-energy neutrino experiments. With two detectors and a total fiducial mass of 2000 tons for solar neutrino physics (equivalently, 3000 tons for geo-neutrino and supernova neutrino physics), the Jinping neutrino experiment will have the potential to identify the neutrinos from the CNO fusion cycles of the Sun, to cover the transition phase for the solar neutrino oscillation from vacuum to matter mixing, and to measure the geo-neutrino flux, including the Th/U ratio. These goals can be fulfilled with mature existing techniques. Efforts on increasing the target mass with multi-modular neutrino detectors and on developing the slow liquid scintillator will increase the Jinping discovery potential in the study of solar neutrinos, geo-neutrinos, supernova neutrinos, and dark matter.
78 citations
TL;DR: Using the one-boson-exchange model, this paper investigated the Lambda(c)(D) over bar (s)*, Sigma(c),D over bar, Xi(c)'s over bar*, and Xi's* over bar* interactions by considering one-eta exchange and/or one-pion exchange contributions and predicted the existence of hidden-charm molecular pentaquarks.
Abstract: Using the one-boson-exchange model, we investigate the Lambda(c)(D) over bar (s)*, Sigma(c)(D) over bar (s)*, Sigma(c)*(D) over bar (s)*, Xi(c)(D) over bar*, Xi(c)'(D) over bar*, and Xi(c)*(D) over bar* interactions by considering the one-eta-exchange and/or one-pion-exchange contributions. We further predict the existence of hidden-charm molecular pentaquarks. Promising candidates for hidden-charm molecular pentaquarks include a Xi(c)'(D) over bar* state with 0(1/2(-)) and the Xi(c)*(D) over bar* states with 0(1/2(-)) and 0(3/2(-)). Experimental searches for these predicted hidden-charm molecular pentaquarks are an interesting future research topic for experiments like LHCb.
66 citations
TL;DR: In this article, the effect of W-helicity fraction measurements on the Wtb effective couplings was investigated using single-top-quark productions at the LHC and Tevatron.
Abstract: We investigate new physics effects on the Wtb effective couplings in a model-independent manner. The new physics effects are summarized as four independent couplings $f_1^L$, $f_1^R$, $f_2^L$ and $f_2^R$. Using single-top-quark productions and W-helicity fraction measurements at the LHC and Tevatron, we perform a global fit to impose constraints on top quark effective couplings. We introduce a set of parameters $x_0$, $x_m$, $x_p$ and $x_5$ to study the correlations among Wtb effective couplings. We show that (i) improving the measurements of $\sigma_t$ and $\sigma_{tW}$ is important in constraining the correlation of $(f_1^R,f_2^R)$ and $(f_2^L,f_2^R)$; (ii) $f_1^L$ and $f_2^R$ are anti-correlated, which is sensitive to all the experiments; (iii) $f_1^R$ and $f_2^L$ are also anti-correlated, which is sensitive to the W-helicity measurements; (iv) the correlation between $f_2^L$ and $f_2^R$ is sensitive to the precision of $\sigma_t$, $\sigma_{tW}$ and $F_0$ measurements. The effective Wtb couplings are studied in three kinds of new physics models: $SU(2)_1 \times SU(2)_2 \times U(1)_X$ models, vector-like quark models and Littlest Higgs model with and without T-parity. The Wtb couplings in the left-right model and the un-unified model are sensitive to the ratio of gauge couplings when the new heavy gauge boson's mass ($M_{W'}$) is less than several hundred GeV, but the constraint is loose if $M_{W'}>1$ TeV. The Wtb couplings in vector-like quark models and the Littlest Higgs models are sensitive to the mixing angles of new heavy particles and SM particles. We also include the constraints of the oblique T-parameter and Zbb couplings which impose much tighter constraints on the mixing angles. We show that the Wtb coupling constraints become relevant if the precision of single top production cross section measurements could be reduced to 1\% relative to the SM predictions in future.
TL;DR: In this article, a measurement of the number of J/psi events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/PSI.
Abstract: A measurement of the number of J/psi events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/psi. The number of J/psi events taken in 2009 is recalculated to be (223.7 +/- 1.4) x 10(6), which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/psi events taken in 2012 is determined to be (1086.9 +/- 6.0) x 10(6). In total, the number of J/psi events collected with the BESIII detector is measured to be (1310.6 +/- 7.0) x 10(6), where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.
TL;DR: In this paper, the large-angle Bhabha scattering events e(+)e(-) -> (gamma)e(+) e(-) and diphoton events e((e(+))e(−) − ε)γγγ ε + ε gamma for the data sets collected at center-of-mass (c.m.) energies between 2.2324 and 4.5900 GeV with the upgraded Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider (BEPCII).
Abstract: By analyzing the large-angle Bhabha scattering events e(+)e(-) -> (gamma)e(+)e(-) and diphoton events e(+)e(-) -> (gamma)gamma gamma for the data sets collected at center-of-mass (c.m.) energies between 2.2324 and 4.5900 GeV (131 energy points in total) with the upgraded Beijing Spectrometer (BESIII) at the Beijing Electron-Positron Collider (BEPCII), the integrated luminosities have been measured at the different c.m. energies, individually. The results are important inputs for the R value and J/Psi resonance parameter measurements.
TL;DR: In this paper, the authors show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high p T implies a non-molecular structure does not hold.
Abstract: The production of the X(3872) as a hadronic molecule in hadron colliders is clarified. We show that the conclusion of Bignamini et al., Phys. Rev. Lett. 103 (2009) 162001, that the production of the X(3872) at high p T implies a non-molecular structure, does not hold. In particular, using the well understood properties of the deuteron wave function as an example, we identify the relevant scales in the production process.
TL;DR: In this paper, the universality of the weak interactions can be tested in semileptonic $b \\to c$ transitions, and in particular in the ratios $R(D^{(*)}) \\equiv \\Gamma(B \\rightarrow D''(*)} \\tau +$ \"missing\" $)/\\Gamma (B \\ rightarrow D ''(*)] \\ell \
u )$ (where $\\ell = \\mu$ or $e$).
Abstract: The universality of the weak interactions can be tested in semileptonic $b \\to c$ transitions, and in particular in the ratios $R(D^{(*)}) \\equiv \\Gamma(B \\rightarrow D^{(*)} \\tau \
u )/\\Gamma(B \\rightarrow D^{(*)} \\ell \
u )$ (where $\\ell = \\mu$ or $e$). Due to the recent differences between the experimental measurements of these observables by BaBar, Belle and LHCb on the one hand and the Standard Model predicted values on the other hand, we study the predicted ratios $R(D^{(*)}) = \\Gamma(B \\rightarrow D^{(*)} \\tau +$ \"missing\" $)/\\Gamma(B \\rightarrow D^{(*)} \\ell \
u )$ in scenarios with an additional sterile heavy neutrino of mass $\\sim 1$ GeV. Further, we evaluate the newly defined ratio $R(0) \\equiv \\Gamma(B \\to \\tau +$ \"missing\" $)/\\Gamma(B \\to \\mu \
u )$ in such scenarios, in view of the future possibilities of measuring the quantity at Belle-II.
TL;DR: In this paper, the authors study the constraints on dark matter annihilation/decay from the Fermi-LAT Isotropic Gamma-Ray Background (IGRB) observation.
Abstract: We study the constraints on dark matter (DM) annihilation/decay from the Fermi-LAT Isotropic Gamma-Ray Background (IGRB) observation. We consider the contributions from both extragalactic and galactic DM components. For DM annihilation, the evolution of extragalactic DM halos is taken into account. We find that the IGRB annihilation constraints under some DM subhalo models can be comparable to those derived from the observations of dwarf spheroidal galaxies and CMB. We also use the IGRB results to constrain the parameter regions accounting for the latest AMS-02 electron-positron anomaly. We find that the majority of DM annihilation/decay channels are strongly disfavored by the latest Fermi-LAT IGRB observation; only DM decays to II-I-R and 4/./, channels may be valid.
TL;DR: In this article, the authors evaluated the statistical precisions of the Higgstrahlung cross section sigma(ZH) and the Higgs mass m(H) measurement at the CEPC in the Z -> mu(+) mu(-) channel.
Abstract: The Circular Electron Positron Collider (CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. It will operate at a center-of-mass energy of 240-250 GeV. The CEPC will accumulate an integrated luminosity of 5 ab(-1) over ten years of operation, producing one million Higgs bosons via the Higgsstrahlung and vector boson fusion processes. This sample allows a percent or even sub-percent level determination of the Higgs boson couplings. With GEANT4-based full simulation and a dedicated fast simulation tool, we have evaluated the statistical precisions of the Higgstrahlung cross section sigma(ZH) and the Higgs mass m(H) measurement at the CEPC in the Z -> mu(+) mu(-) channel. The statistical precision of sigma(ZH) (m(H)) measurement could reach 0.97% (6.9 MeV) in the model-independent analysis which uses only the information from Z boson decays. For the standard model Higgs boson, the mu precision could be improved to 5.4 MeV by including the information from Higgs decays. The impact of the TPC size on these measurements is investigated. In addition, we studied the prospect of measuring the Higgs boson decaying into invisible final states at the CEPC. With the Standard Model ZH production rate, the upper limit of B(H -> inv.) could reach 1.2% at 95% confidence level.
TL;DR: The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton low-background liquid scintillator (LS) detector with energy resolution as mentioned in this paper, which has the potential to reach a sensitivity (at 90% C. L.) to of 1.9% at the Q value of (136)Xe 0νββ decay.
Abstract: In the past few decades, numerous searches have been made for the neutrinoless double-beta decay (0νββ) process, aiming to establish whether neutrinos are their own antiparticles (Majorana neutrinos), but no 0νββ decay signal has yet been observed. A number of new experiments are proposed but they ultimately suffer from a common problem: the sensitivity may not increase indefinitely with the target mass. We have performed a detailed analysis of the physics potential by using the Jiangmen Underground Neutrino Observatory (JUNO) to improve the sensitivity to 0νββ up to a few meV, a major step forward with respect to the experiments currently being planned. JUNO is a 20 kton low-background liquid scintillator (LS) detector with energy resolution, now under construction. It is feasible to build a balloon filled with enriched xenon gas (with (136)Xe up to 80%) dissolved in LS, inserted into the central region of the JUNO LS. The energy resolution is ∼1.9% at the Q-value of (136)Xe 0νββ decay. Ultra-low background is the key for 0νββ decay searches. Detailed studies of background rates from intrinsic 2νββ and (8)B solar neutrinos, natural radioactivity, and cosmogenic radionuclides (including light isotopes and (137)Xe) were performed and several muon veto schemes were developed. We find that JUNO has the potential to reach a sensitivity (at 90% C. L.) to of 1.8×10(28) yr (5.6×10(27) yr) with ∼50 tons (5 tons) of fiducial (136)Xe and 5 years exposure, while in the 50-ton case the corresponding sensitivity to the effective neutrino mass, m (β)(β), could reach (5–12) meV, covering completely the allowed region of inverted neutrino mass ordering.
TL;DR: In this paper, the authors presented the determination of proton parton distribution functions under the dynamical parton model assumption by applying DGLAP equations with GLR-MQ-ZRS corrections.
Abstract: Determination of proton parton distribution functions is presented under the dynamical parton model assumption by applying DGLAP equations with GLR-MQ-ZRS corrections. We provide two data sets, referred to as IMParton16, which are from two different nonperturbative inputs. One is the naive input of three valence quarks and the other is the input of three valence quarks with flavor-asymmetric sea components. Basically, both data sets are compatible with the experimental measurements at high scale (Q(2) > 2 GeV2). Furthermore, our analysis shows that the input with flavor-asymmetric sea components better reproduces the structure functions at high Q2. Generally, the parton distribution functions obtained, especially the gluon distribution function, are good options for inputs to simulations of high energy scattering processes. The analysis is performed under the fixed-flavor number scheme for n(f) = 3, 4, 5. Both data sets start from very low scales, around 0.07 GeV2, where the nonperturbative input is directly connected to the simple picture of the quark model. These results may shed some lights on the origin of the parton distributions observed at high Q(2).
TL;DR: In this paper, a phenomenological quark-antiquark potential (Coulomb plus linear confinement) model with a Gaussian wave function is used for detailed study of masses of the ground, orbitally and radially excited states of heavy-light Qq, (Q=c,q=u/d,s) mesons.
Abstract: The framework of a phenomenological quark-antiquark potential (Coulomb plus linear confinement) model with a Gaussian wave function is used for detailed study of masses of the ground, orbitally and radially excited states of heavy-light Qq, (Q=c,q=u/d,s) mesons. We incorporate a correction to the potential energy term and relativistic corrections to the kinetic energy term of the Hamiltonian. The spin-hyperfine, spin-orbit and tensor interactions incorporating the effect of mixing are employed to obtain the pseudoscalar, vector, radially and orbitally excited state meson masses. The Regge trajectories in the (J,M (2)) and (n (r),M (2)) planes for heavy-light mesons are investigated with their corresponding parameters. Leptonic and radiative leptonic decay widths and corresponding branching ratios are computed. The mixing parameters are also estimated. Our predictions are in good agreement with experimental results as well as lattice and other theoretical models.
TL;DR: In this article, the perturbative QCD (PQCD) factorization approach was employed for the quasi-two-body decays, where the pion pair comes from the S-wave resonance f (0)(X).
Abstract: By employing the perturbative QCD (PQCD) factorization approach, we study the quasi-two-body decays, where the pion pair comes from the S-wave resonance f (0)(X). The Breit–Wigner formula for the f (0)(500) and f (0)(1500) resonances and the Flatte model for the f (0)(980) resonance are adopted to parameterize the time-like scalar form factors in the two-pion distribution amplitudes. As a comparison, Bugg's model is also used for the wide f (0)(500) in this work. For decay rates, we found the following PQCD predictions: (a) when the contributions from f (0)(980) and f (0)(1500) are all taken into account, (b) in the Breit-Wigner model and in Bugg's model.
TL;DR: In this paper, the authors assign the Y(4390) and Y(4220) to vector molecular states DD(1) (2420) and, respectively, and study their masses and pole residues in detail with the QCD sum rules.
Abstract: In this article, we assign the Y(4390) and Y(4220) to be the vector molecular states DD(1) (2420) and , respectively, and study their masses and pole residues in detail with the QCD sum rules. The present calculations only favor assigning the Y(4390) to be the DD(1)(1(−)( )(−)) molecular state.
TL;DR: FELiChEM is a new experimental facility under construction at the University of Science and Technology of China (USTC), whose core device is two free electron laser oscillators generating middle infrared and far-infrared laser and covering the spectral range of 2.5-200 μm.
Abstract: FELiChEM is a new experimental facility under construction at the University of Science and Technology of China (USTC). Its core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 2.5–200 μm. It will be a dedicated infrared light source aiming at energy chemistry research. We present the brief design of the FEL oscillators, with the emphasis put on the middle-infrared oscillator. Most of the basic parameters are determined and the anticipated performance of the output radiation is given. The first light of FELiChEM is targeted for the end of 2017.
TL;DR: In this paper, a new vector gauge boson X(16.7) was found to be the solution of both NuTeV anomaly and the $(g-2){mu} puzzle.
Abstract: A recent experimental study of excited $^{8}\\!Be$ decay to its ground state reveals an anomaly in the final states angle distribution. This exceptional result is attributed to a new vector gauge boson X(16.7). We study the significance of this new boson, especially its effect in anomalies observed in long-lasting experimental measurements. By comparing the discrepancies between the standard model predictions and the experimental results, we manage to find out the values and regions of the couplings of X(16.7) to muon and muon neutrino. In this work, we find that the newly observed boson X(16.7) may be the solution of both NuTeV anomaly and the $(g-2)_{\\mu}$ puzzle.
TL;DR: Gulmez et al. as discussed by the authors proposed an effective potential for the Bethe-Salpeter equation, which when used with the ρρ loop function provides a state with J 2 around the energy of the f 2(1270).
Abstract: We examine in detail a recent work (D. Gulmez, U. G. Meisner and J. A. Oller, Eur. Phys. J. C, 77: 460 (2017)), where improvements to make ρρ scattering relativistically covariant are made. The paper has the remarkable conclusion that the J=2 state disappears with a potential which is much more attractive than for J=0, where a bound state is found. We trace this abnormal conclusion to the fact that an "on-shell" factorization of the potential is done in a region where this potential is singular and develops a large discontinuous and unphysical imaginary part. A method is developed, evaluating the loops with full ρ propagators, and we show that they do not develop singularities and do not have an imaginary part below threshold. With this result for the loops we define an effective potential, which when used with the Bethe-Salpeter equation provides a state with J=2 around the energy of the f 2(1270). In addition, the coupling of the state to ρρ is evaluated and we find that this coupling and the T matrix around the energy of the bound state are remarkably similar to those obtained with a drastic approximation used previously, in which the q 2 terms of the propagators of the exchanged ρ mesons are dropped, once the cut-off in the ρρ loop function is tuned to reproduce the bound state at the same energy.
TL;DR: In this article, the potential of a diffraction-limited storage ring (DLSR) design can be explored with a successive and iterative implementation of the multiobjective particle swarm optimization (MOPSO) and multi-objective genetic algorithm (MOGA).
Abstract: In the lattice design of a diffraction-limited storage ring (DLSR) consisting of compact multi-bend achromats (MBAs), it is challenging to simultaneously achieve an ultralow emittance and a satisfactory nonlinear performance, due to extremely large nonlinearities and limited tuning ranges of the element parameters. Nevertheless, in this paper we show that the potential of a DLSR design can be explored with a successive and iterative implementation of the multi-objective particle swarm optimization (MOPSO) and multi-objective genetic algorithm (MOGA). For the High Energy Photon Source, a planned kilometer-scale DLSR, optimizations indicate that it is feasible to attain a natural emittance of about 50 pm·rad, and simultaneously realize a sufficient ring acceptance for on-axis longitudinal injection, by using a hybrid MBA lattice. In particular, this study demonstrates that a rational combination of the MOPSO and MOGA is more effective than either of them alone, in approaching the true global optima of an explorative multi-objective problem with many optimizing variables and local optima.
TL;DR: In this article, a general approach to solve an Einstein-Maxwell system to describe a static spherically symmetric anisotropic strange matter distribution with linear equation of state in terms of two generating functions is presented.
Abstract: We report a general approach to solve an Einstein-Maxwell system to describe a static spherically symmetric anisotropic strange matter distribution with linear equation of state in terms of two generating functions. It is examined by choosing Tolmann IV type potential for one of the gravitational potentials and a physically reasonable choice for the electric field. Hence, the generated model satisfies all the required major physical properties of a realistic star. The effect of electric charge on physical properties is highlighted.
TL;DR: In this article, the discovery and exclusion limits for both Dirac and Majorana neutrinos were shown using both the Cut-and-Count (CC) and Multi-Variate Analysis (MVA) methods.
Abstract: We present a search strategy for both Dirac and Majorana sterile neutrinos from the purely leptonic decays of W± → e± e± μ∓ ν and μ± μ± e∓ ν at the 14 TeV LHC. The discovery and exclusion limits for sterile neutrinos are shown using both the Cut-and-Count (CC) and Multi-Variate Analysis (MVA) methods. We also discriminate between Dirac and Majorana sterile neutrinos by exploiting a set of kinematic observables which differ between the Dirac and Majorana cases. We find that the MVA method, compared to the more common CC method, can greatly enhance the discovery and discrimination limits. Two benchmark points with sterile neutrino mass m N = 20 GeV and 50 GeV are tested. For an integrated luminosity of 3000 fb−1, sterile neutrinos can be found with 5σ significance if heavy-to-light neutrino mixings |U Ne |2 ∼ |U Nμ |2∼ 10−6, while Majorana vs. Dirac discrimination can be reached if at least one of the mixings is of order 10−5.