119087832
Candidate chiral doublet bands in the odd-odd nucleus Cs 126
The candidate chiral doublet bands recently observed in $^{126}$Cs have been extended to higher spins, several new linking transitions between the two partner members of the chiral doublet bands are observed, and $\gamma$$-$intensities related to the chiral doublet bands are presented by analyzing the $\gamma$$-$$\gamma$ coincidence data collected earlier at the NORDBALL through the $^{116}$Cd$($$^{14}$N, 4n$)$$^{126}$Cs reaction at a beam energy of 65 MeV. The intraband $B(M1)/B(E2)$ and interband $B(M1)_{in}/B(M1)_{out}$ ratios and the energy staggering parameter, S(I), have been deduced for these doublet bands. The results are found to be consistent with the chiral interpretation for the two structures. Furthermore, the observation of chiral doublet bands in $^{126}$Cs together with those in $^{124}$Cs, $^{128}$Cs, $^{130}$Cs and $^{132}$Cs also indicates that the chiral conditions do not change rapidly with decreasing neutron number in these odd-odd Cesium isotopes.
123285492
Examining B(M1) staggering as a fingerprint for chiral doublet bands
The electromagnetic transitions of the doublet bands with different triaxiality parameter gamma are discussed in the particle rotor model with pi Th(11/2) circle times vh(11/2)(-1) configuration. It is found that B(M1) staggering as well as the resulting B(M1)/B(E2) and B(M1)(in)/B(M1)(out) staggering are sensitive to the triaxiality parameter gamma, and they associate strongly with the characters of nuclear chirality for 15 degrees <= gamma <= 30 degrees, i.e., the staggering is weak in the chiral vibration region while strong in the static chirality region. For partner bands with near degenerate energy spectra and similar B(M1) and B(E2) transitions, the strong B(M1) staggering can be used as a fingerprint for the static chirality.
118485729
Chirality in odd-A Rh isotopes within the triaxial particle rotor model
By adopting the fully quantal triaxial particle-rotor model, the candidate chiral doublet bands in odd-A nuclei {sup 103}Rh and {sup 105}Rh with {pi}g{sub 9/2}{sup -1} x {nu}h{sub 11/2}{sup 2} configuration are studied. For the doublet bands in both nuclei, agreement is excellent for the observed energies over the entire spin range and B(M1)/B(E2) at higher spin range. The evolution of the chiral geometry with angular momentum is discussed in detail by using the angular momentum components and their probability distributions. Chirality is found to change from chiral vibration to nearly static chirality at spin I=37/2 and back to another type of chiral vibration at higher spin. The influence of the triaxial deformation {gamma} is also studied.
113400995
Vorticity and magnetic field production in relativistic ideal fluids
In the framework of relativistic ideal hydrodynamics, we study the production mechanism for vorticity and magnetic field in relativistic ideal fluids. It is demonstrated that in the uncharged fluids the thermal vorticity will always satisfy the Kelvin's theorem and the circulation must be conserved. However, in the charged fluids, the vorticity and magnetic field can be produced by the interaction between the entropy gradients and the fluid velocity gradients. Especially, in the multiple charged fluids, the vorticity and magnetic field can be produced by the interaction between the inhomogeneous charge density ratio and the fluid velocity gradients even if the entropy distribution is homogeneous, which provides another mechanism for the production of vorticity and magnetic field in relativistic plasmas or in the early universe.
15019330
Chirality in odd-A nucleus 135Nd in particle rotor model
Abstract A particle rotor model is developed which couples several valence protons and neutrons to a rigid triaxial rotor core. It is applied to investigating the chirality in odd- A nucleus 135 Nd with π h 11 / 2 2 ⊗ ν h 11 / 2 − 1 configuration for the first time in a fully quantal approach. For the two chiral sister bands, the observed energies and the B ( M 1 ) and B ( E 2 ) values for the in-band as well as interband transitions are reproduced excellently. Root mean square values of the angular momentum components and their probability distributions are used for discussing in detail the chiral geometry of the aplanar rotation and its evolution with angular momentum. Chirality is found to change from a soft chiral vibration to nearly static chirality at spin I = 39 / 2 and back to another type of chiral vibration at higher spin.
120766563
New insight into the shape coexistence and shape evolution of Yb-157
High-spin states in Yb-157 have been populated in the Sm-144( O-16,3n)Yb-157 fusion-evaporation reaction at a beam energy of 85 MeV. Two rotational bands built on the nu f(7/2) and nu h(9/2) intrinsic states, respectively, have been established for the first time. The newly observed nu f(7/2) band and previously known nu i(13/2) band in Yb-157 are discussed in terms of total Routhian surface methods and compared with the structures in the neighboring N = 87 isotones. The structural characters observed in Yb-157 provide evidence for shape coexistence of three distinct shapes: prolate, triaxial, and oblate. At higher spins, both the nu f(7/2) band and nu i(13/2) band in Yb-157 undergo a shape evolution with sizable alignments occurring.
118632632
Heavy fragment radioactivity of Pu-238: Si and Mg emission
In addition to its two known hadronic decay modes\char22{}alpha decay (half-life 88 yr) and spontaneous fission (5\ifmmode\times\else\texttimes\fi{}${10}^{10}$ yr)\char22{}we have found that $^{238}\mathrm{Pu}$ also decays by emission of a Mg nucleus (\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}${10}^{18}$ yr) and by emission of a Si nucleus (\ensuremath{\sim}6\ifmmode\times\else\texttimes\fi{}${10}^{17}$ yr). This extends to four (the other two being $^{14}\mathrm{C}$ emission and Ne emission) the number of known modes of decay by emission of a fragment of mass between that of an alpha particle and that resulting from fission. The branching ratios relative to alpha decay are the lowest yet observed: \ensuremath{\sim}6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}17}$ for Mg emission and 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}16}$ for Si emission.
209835699
Search for anomalous production of events with two photons and additional energetic objects at CDF
We present results of a search for anomalous production of two photons together with an electron, muon, τ lepton, missing transverse energy, or jets using pp collision data from 1.1–2.0  fb-1 of integrated luminosity collected by the Collider Detector at Fermilab (CDF). The event yields and kinematic distributions are examined for signs of new physics without favoring a specific model of new physics. The results are consistent with the standard model expectations. The search employs several new analysis techniques that significantly reduce instrumental backgrounds in channels with an electron and missing transverse energy.
17710652
Colliding Clouds: The Star Formation Trigger of the Stellar Cluster around BD +40 4124
We present BIMA and SCUBA observations of the young cluster associated with BD +40 4124 in the dense molecular gas tracer CS J = 2 → 1 and the continuum dust emission at λ = 3.1 mm and 850 μm. The dense gas and dust in the system are aligned in a long ridge morphology extending ~0.4 pc with 16 gas clumps of estimated masses ranging from 0.14 to 1.8 M☉. A north-south variation in the CS center line velocity can be explained with a two-cloud model. We posit that the BD +40 4124 stellar cluster formed from a cloud-cloud collision. The largest line widths occur near V1318 Cyg S, a massive star affecting its natal environment. In contrast, the dense gas near the other, more evolved, massive stars displays no evidence for disruption; the material must either be processed into the star, dissipate, or relax fairly quickly. The more evolved low-mass protostars are more likely to be found near the massive stars. If the majority of low-mass stars are coeval, the seemingly evolved low-mass protostars are not older: the massive stars have eroded their structures. Finally, at the highest resolution, the λ = 3.1 mm dust emission is resolved into a flattened structure 3100 × 1500 AU with an estimated mass of 3.4 M☉. The continuum and CS emission are offset by 11 from the southern binary source. A simple estimate of the extinction due to the continuum emission structure is AV ~ 700 mag. From the offset and because the southern source is detected in the optical, the continuum emission is from a previously unknown very young, intermediate-mass, embedded stellar object.
208868987
Search for Higgs bosons produced in association with b quarks
We present a search for neutral Higgs bosons φ decaying into bb¯, produced in association with b quarks in ppb¯ collisions. This process could be observable in supersymmetric models with high values of tan β. The event sample corresponds to 2.6 fb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron collider. We search for an enhancement in the mass of the two leading jets in events with three jets identified as coming from b quarks using a displaced vertex algorithm. A data-driven procedure is used to estimate the dijet mass spectrum of the nonresonant multijet background. The contributions of backgrounds and a possible Higgs boson signal are determined by a two-dimensional fit of the data, using the dijet mass together with an additional variable which is sensitive to the flavor composition of the three tagged jets. We set mass-dependent limits on σ(ppb¯ = φb) x Β(φ= bb¯) which are applicable for a narrow scalar particle φ produced in association with b quarks. We also set limits on tan β in supersymmetric Higgs models including the effects of the Higgs boson width.
6418500
Search for new dielectron resonances and Randall-Sundrum gravitons at the collider detector at Fermilab.
A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of 5.7  fb(-1) is presented. No significant excess over the expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed (960  GeV/c(2)) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the 5.4  fb(-1) diphoton analysis, the RS-graviton lower-mass limit for the coupling k/M¯(Pl)=0.1 is 1058  GeV/c(2), making it the strongest limit to date.