BCS theory for s+g-wave superconductivity borocarbides Y(Lu)Ni2_2B2_2C

The s+g mixed gap function \Delta_k=\Delta {[(1-x)-x\sin^4\theta\cos4\phi]} (x: weight of g-wave component) has been studied within BCS theory. By suitable consideration of the pairing interaction, we have confirmed that the coexistence of s- and g-wave, as well as the state with equal s and g amplitudes (i.e., x=1/2) may be stable. This provides the semi-phenomenological theory for the s+g-wave superconductivity with point nodes which has been observed experimentally in borocarbides YNi_2B_2C and possibly in LuNi_2B_2C.Comment: 5 pages, 3 figure

A boundary value problem for the five-dimensional stationary rotating black holes

We study the boundary value problem for the stationary rotating black hole solutions to the five-dimensional vacuum Einstein equation. Assuming the two commuting rotational symmetry and the sphericity of the horizon topology, we show that the black hole is uniquely characterized by the mass, and a pair of the angular momenta.Comment: 16 pages, no figure

Five Dimensional Rotating Black Hole in a Uniform Magnetic Field. The Gyromagnetic Ratio

In four dimensional general relativity, the fact that a Killing vector in a vacuum spacetime serves as a vector potential for a test Maxwell field provides one with an elegant way of describing the behaviour of electromagnetic fields near a rotating Kerr black hole immersed in a uniform magnetic field. We use a similar approach to examine the case of a five dimensional rotating black hole placed in a uniform magnetic field of configuration with bi-azimuthal symmetry, that is aligned with the angular momenta of the Myers-Perry spacetime. Assuming that the black hole may also possess a small electric charge we construct the 5-vector potential of the electromagnetic field in the Myers-Perry metric using its three commuting Killing vector fields. We show that, like its four dimensional counterparts, the five dimensional Myers-Perry black hole rotating in a uniform magnetic field produces an inductive potential difference between the event horizon and an infinitely distant surface. This potential difference is determined by a superposition of two independent Coulomb fields consistent with the two angular momenta of the black hole and two nonvanishing components of the magnetic field. We also show that a weakly charged rotating black hole in five dimensions possesses two independent magnetic dipole moments specified in terms of its electric charge, mass, and angular momentum parameters. We prove that a five dimensional weakly charged Myers-Perry black hole must have the value of the gyromagnetic ratio g=3.Comment: 23 pages, REVTEX, v2: Minor changes, v3: Minor change

Impurity effects on s+g-wave superconductivity in borocarbides Y(Lu)Ni_2B_2C

Recently a hybrid s+g-wave pairing is proposed to describe the experimental observation for a nodal structure of the superconducting gap in borocarbide YNi$_2$B$_2$C and possibly LuNi$_2$B$_2$C. In this paper the impurity effects on the s+g-wave superconductivity are studied in both Born and unitarity limit. The quasiparticle density of states and thermodynamics are calculated. It is found that the nodal excitations in the clean system are immediately prohibited by impurity scattering and a finite energy gap increases quickly with the impurity scattering rate. This leads to an activated behavior in the temperature dependence of the specific heat. Qualitative agreement with the experimental results is shown. Comparison with d-wave and some anisotropic s-wave studied previously is also made.Comment: 6 pages, 6 eps figure

Search for CP Violation in Charged D Meson Decays

We report results of a search for CP violation in the singly Cabibbo-suppressed decays D+ -> K- K+ pi+, phi pi+, K*(892)0 K+, and pi- pi+ pi+ based on data from the charm hadroproduction experiment E791 at Fermilab. We search for a difference in the D+ and D- decay rates for each of the final states. No evidence for a difference is seen. The decay rate asymmetry parameters A(CP), defined as the difference in the D+ and D- decay rates divided by the sum of the decay rates, are measured to be: A(CP)(K K pi) = -0.014 +/- 0.029, A(CP)(phi pi) = -0.028 +/- 0.036, A(CP)(K*(892) K) = -0.010 +/- 0.050, and A(CP)(pi pi pi) = -0.017 +/- 0.042.Comment: 13 pages, 5 figures, 1 table; Elsevier LaTe

Spatial infinity in higher dimensional spacetimes

Motivated by recent studies on the uniqueness or non-uniqueness of higher dimensional black hole spacetime, we investigate the asymptotic structure of spatial infinity in n-dimensional spacetimes($n \geq 4$). It turns out that the geometry of spatial infinity does not have maximal symmetry due to the non-trivial Weyl tensor {}^{(n-1)}C_{abcd} in general. We also address static spacetime and its multipole moments P_{a_1 a_2 ... a_s}. Contrasting with four dimensions, we stress that the local structure of spacetimes cannot be unique under fixed a multipole moments in static vacuum spacetimes. For example, we will consider the generalized Schwarzschild spacetimes which are deformed black hole spacetimes with the same multipole moments as spherical Schwarzschild black holes. To specify the local structure of static vacuum solution we need some additional information, at least, the Weyl tensor {}^{(n-2)}C_{abcd} at spatial infinity.Comment: 6 pages, accepted for publication in Physical Review D, published versio

Gravitational collapse of a Hagedorn fluid in Vaidya geometry

The gravitational collapse of a high-density null charged matter fluid, satisfying the Hagedorn equation of state, is considered in the framework of the Vaidya geometry. The general solution of the gravitational field equations can be obtained in an exact parametric form. The conditions for the formation of a naked singularity, as a result of the collapse of the compact object, are also investigated. For an appropriate choice of the arbitrary integration functions the null radial outgoing geodesic, originating from the shell focussing central singularity, admits one or more positive roots. Hence a collapsing Hagedorn fluid could end either as a black hole, or as a naked singularity. A possible astrophysical application of the model, to describe the energy source of gamma-ray bursts, is also considered.Comment: 14 pages, 2 figures, to appear in Phys. Rev.

Topological Charged Black Holes in High Dimensional Spacetimes and Their Formation from Gravitational Collapse of a Type II Fluid

Topological charged black holes coupled with a cosmological constant in $R^{2}\times X^{D-2}$ spacetimes are studied, where $X^{D-2}$ is an Einstein space of the form ${}^{(D-2)}R_{AB} = k(D-3) h_{AB}$. The global structure for the four-dimensional spacetimes with $k = 0$ is investigated systematically. The most general solutions that represent a Type $II$ fluid in such a high dimensional spacetime are found, and showed that topological charged black holes can be formed from the gravitational collapse of such a fluid. When the spacetime is (asymptotically) self-similar, the collapse always forms black holes for $k = 0, -1$, in contrast to the case $k = 1$, where it can form either balck holes or naked singularities.Comment: 14 figures, to appear in Phys. Rev.

Branching Fractions for D0 -> K+K- and D0 -> pi+pi-, and a Search for CP Violation in D0 Decays

Using the large hadroproduced charm sample collected in experiment E791 at Fermilab, we have measured ratios of branching fractions for the two-body singly-Cabibbo-suppressed charged decays of the D0: (D0 -> KK)/(D0 -> Kpi) = 0.109 +- 0.003 +- 0.003, (D0 -> pipi)/(D0 -> Kpi) = 0.040 +- 0.002 +- 0.003, and (D0 -> KK)/(D0 -> pipi) = 2.75 +- 0.15 +- 0.16. We have looked for differences in the decay rates of D0 and D0bar to the CP eigenstates K+K- and pi+pi-, and have measured the CP asymmetry parameters A_CP(K+K-) = -0.010 +- 0.049 +- 0.012 and A_CP(pi+pi-) = -0.049 +- 0.078 +- 0.030, both consistent with zero.Comment: 10 Postscript pages, including 2 figures. Submitted to Phys. Lett.

Prevalence of High-Risk Human Papillomavirus by RNA Assay in Home Self-Collected Samples among Underscreened People in North Carolina

Background Low-income and uninsured people with a cervix (PWC) are at the highest risk of being underscreened for cervical cancer. We evaluated the prevalence of high-risk human papillomavirus (hrHPV) on home self-collected samples, as well as rates of in-clinic follow-up and risk factors associated with hrHPV positivity in this at-risk population. Methods My Body My Test 3 was conducted between 2016 and 2019 in North Carolina among individuals aged 25 to 64 years, overdue for cervical cancer screening, and with incomes of <250% of the US Federal Poverty Level. Our analytic sample included participants randomized to the self-collection arm who returned self-collected cervicovaginal brush samples for HPV testing (n = 329). Samples were tested for 14 hrHPV types by an HPV RNA assay and further genotyped for HPV-16 and HPV-18/45. We examined behavioral risk factors for hrHPV positivity using logistic regression and between-subject t tests. Results High-risk HPV RNA prevalence was 16% (n = 52/329) in self-collected samples. Of the hrHPV-positive participants, 24 (46%) presented for in-clinic cervical cancer screening, compared with 56 (20%) of hrHPV-negative participants. Those with ≥2 sexual partners in the past year were twice as likely to be hrHPV positive in adjusted analyses (adjusted odds ratio, 2.00 [95% confidence interval, 1.03-3.88]). High-risk HPV-positive and HPV-negative participants had similar attitudes toward screening, with the exception of hrHPV-positive participants who reported a lower perceived risk of cervical cancer than those who were hrHPV negative (P < 0.05). Conclusion The hrHPV RNA prevalence was similar to findings in other underscreened PWC in the United States. Efforts to reach underscreened PWC are critical for cervical cancer prevention. Future studies aimed at home self-collection should address methods of increasing clinic attendance and completion of treatment among those with HPV-positive results