It's Confirmed: Black Holes Do Come in Medium Sizes

It's Confirmed: Black Holes Do Come in Medium Sizes:



"Black holes do indeed come in three sizes: small, medium and extra large, a new study suggests."



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Middle Mass Black Holes

A 400-solar-mass black hole in the galaxy M82 : Nature : Nature Publishing Group

A 400-solar-mass black hole in the galaxy M82 : Nature : Nature Publishing Group:



 "M82 X-1, the brightest X-ray source in the galaxy M82, has been thought to be an intermediate-mass black hole (100 to 10,000 solar masses) because of its extremely high luminosity and variability characteristics1, 2, 3, 4, 5, 6, although some models suggest that its mass may be only about 20 solar masses3, 7. The previous mass estimates were based on scaling relations that use low-frequency characteristic timescales which have large intrinsic uncertainties8, 9. For stellar-mass black holes, we know that the high-frequency quasi-periodic oscillations (100–450 hertz) in the X-ray emission that occur in a 3:2 frequency ratio are stable and scale in frequency inversely with black hole mass with a reasonably small dispersion10, 11, 12, 13, 14, 15. The discovery of such stable oscillations thus potentially offers an alternative and less ambiguous means of mass determination for intermediate-mass black holes, but has hitherto not been realized. Here we report stable, twin-peak (3:2 frequency ratio) X-ray quasi-periodic oscillations from M82 X-1 at frequencies of 3.32 ± 0.06 hertz and 5.07 ± 0.06 hertz. Assuming that we can extrapolate the inverse-mass scaling that holds for stellar-mass black holes, we estimate the black hole mass of M82 X-1 to be 428 ± 105 solar masses. In addition, we can estimate the mass using the relativistic precession model, from which we get a value of 415 ± 63 solar masses."



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[1308.1682] Can the 62 day X-ray period of the Ultraluminous X-ray source M82 X-1 be due to a precessing accretion disk?

[1308.1682] Can the 62 day X-ray period of the Ultraluminous X-ray source M82 X-1 be due to a precessing accretion disk?:



 "We have analyzed all archival RXTE/PCA monitoring observations of the ultraluminous X-ray source (ULX) M82 X-1 in order to study the properties of its 62 day X-ray period (Kaaret & Feng 2007). Based on its high coherence it has been argued that the observed period is the orbital period of the binary. Utilizing a much longer data set than in previous studies we find: (1) The phase-resolved X-ray (3-15 keV) spectra -- modeled with a thermal accretion disk and a power-law -- suggest that the accretion disk's contribution to the total flux is strongly modulated with phase. (2) Suggestive evidence for a sudden phase shift--of approximately 0.4 in phase (25 days)-- between the first and the second halves of the light curve separated by roughly 1000 days. If confirmed, the implied timescale to change the period is ~ 10 yrs, which is exceptionally fast for an orbital phenomenon. These two independent pieces of evidence are consistent with the periodicity being due to a precessing accretion disk, similar to the super-orbital periods observed in systems like Her X-1, LMC X-4, and SS433. However, the timing evidence for a change in the period needs to be confirmed with additional observations. This should be possible with further monitoring of M82 with instruments such as the Swift X-ray telescope (XRT)."



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[1312.1228] Determination of $|V_{us}|$ from a lattice-QCD calculation of the $K\to\pi\ell\nu$ semileptonic form factor with physical quark masses

[1312.1228] Determination of $|V_{us}|$ from a lattice-QCD calculation of the $K\to\pi\ell\nu$ semileptonic form factor with physical quark masses:



 "We calculate the kaon semileptonic form factor f+(0) from lattice QCD, working, for the first time, at the physical light-quark masses. We use gauge configurations generated by the MILC collaboration with Nf=2+1+1 flavors of sea quarks, which incorporate the effects of dynamical charm quarks as well as those of up, down, and strange. We employ data at three lattice spacings to extrapolate to the continuum limit. Our result, f+(0)=0.9704(32), where the error is the total statistical plus systematic uncertainty added in quadrature, is the most precise determination to date. Combining our result with the latest experimental measurements of K semileptonic decays, one obtains the Cabibbo-Kobayashi-Maskawa matrix element |Vus|=0.22290(74)(52), where the first error is from f+(0) and the second one is from experiment. In the first-row test of Cabibbo-Kobayashi-Maskawa unitarity, the error stemming from |Vus| is now comparable to that from |Vud|."



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[1401.6298] The Green Function for the BFKL Pomeron and the Transition to DGLAP Evolution

[1401.6298] The Green Function for the BFKL Pomeron and the Transition to DGLAP Evolution:



"We consider the (process-independent) Green function for the BFKL equation in the next-to-leading order approximation, with running coupling, and explain how, within the semi-classical approximation, it is related to Green function of the Airy equation. The unique Green function is obtained from a combination of its required ultraviolet behaviour compatible with asymptotic freedom and an infrared limit phase imposed by the non-perturbative sector of QCD. We show that at sufficiently large gluon transverse momenta the corresponding gluon density matches that of the DGLAP analysis, whereas for relatively small values of the gluon transverse momentum the gluon distribution is sensitive to the Regge poles, whose positions are determined both by the non-pertubative QCD dynamics and physics at large transverse momenta."



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A World of Creatures That Hide in the Open - NYTimes.com

A World of Creatures That Hide in the Open - NYTimes.com:



 "Sönke Johnsen scuba dives in the middle of the ocean, far from land, miles above the seafloor. There are no shipwrecks to explore, no reefs to admire, just a disorienting oasis of blue."



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Julian Assange Says He Will Leave Embassy ‘Soon’ - NYTimes.com

Julian Assange Says He Will Leave Embassy ‘Soon’ - NYTimes.com:



 "LONDON — Julian Assange, the founder of WikiLeaks, who was given asylum in the Ecuadorean Embassy here two years ago, said Monday that he “will be leaving the embassy soon,” but he provided no specifics."



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[1401.7848] Realizing three generations of the Standard Model fermions in the type IIB matrix model

[1401.7848] Realizing three generations of the Standard Model fermions in the type IIB matrix model:



"We discuss how the Standard Model particles appear from the type IIB matrix model, which is considered to be a nonperturbative formulation of superstring theory. In particular, we are concerned with a constructive definition of the theory, in which we start with finite-N matrices and take the large-N limit afterwards. In that case, it was pointed out recently that realizing chiral fermions in the model is more difficult than it had been thought from formal arguments at N=infinity and that introduction of a matrix version of the warp factor is necessary. Based on this new insight, we show that two generations of the Standard Model fermions can be realized by considering a rather generic configuration of fuzzy S^2 and fuzzy S^2 * S^2 in the extra dimensions. We also show that three generations can be obtained by squashing one of the S^2's that appear in the configuration. Chiral fermions appear at the intersections of the fuzzy manifolds with nontrivial Yukawa couplings to the Higgs field, which can be calculated from the overlap of their wave functions."



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Four dimensional supersymmetric Yang-Mills quantum mechanics with three colors

The D=4 supersymmetric Yang-Mills quantum mechanics with SU(2) and SU(3) gauge symmetry groups is studied. A numerical method to find finite matrix representation of the Hamiltonian is presented in detail. It is used to find spectrum of the theory. In the SU(2) case there are bound states in all channels with definite total number of fermions and angular momentum. For 2,3,4 fermions continuous and discrete spectra coexist in the same range of energies. These results are confirmation of earlier studies. With SU(3) gauge group, the continuous spectrum is moved to sectors with more fermions. Supersymmetry generators are used to identify supermultiplets and determine the level of restoration of supersymmetry for a finite cutoff. For both theories, with SU(2) and SU(3) symmetry, wavefunctions are studied and different behavior of bound and scattering states is observed.

arXiv

The Forever Slump - NYTimes.com

The Forever Slump - NYTimes.com:



"It’s hard to believe, but almost six years have passed since the fall of Lehman Brothers ushered in the worst economic crisis since the 1930s. Many people, myself included, would like to move on to other subjects. But we can’t, because the crisis is by no means over. Recovery is far from complete, and the wrong policies could still turn economic weakness into a more or less permanent depression."



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Top Math Prize Has Its First Female Winner - NYTimes.com

Top Math Prize Has Its First Female Winner - NYTimes.com:



 "An Iranian mathematician is the first woman ever to receive a Fields Medal, often considered to be mathematics’ equivalent of the Nobel Prize."



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[1106.3942] Gauge bosons at zero and finite temperature

[1106.3942] Gauge bosons at zero and finite temperature:



 "Gauge theories of the Yang-Mills type are the single most important building block of the standard model and beyond. Since Yang-Mills theories are gauge theories their elementary particles, the gauge bosons, cannot be described without fixing a gauge. Beyond perturbation theory, gauge-fixing in non-Abelian gauge theories is obstructed by the Gribov-Singer ambiguity. The construction and implementation of a method-independent gauge-fixing prescription to resolve this ambiguity is the most important step to describe gauge bosons beyond perturbation theory. Proposals for such a procedure, generalizing the perturbative Landau gauge, are described here. Their implementation are discussed for two example methods, lattice gauge theory and the quantum equations of motion. The most direct access to the properties of the gauge bosons is provided by their correlation functions. The corresponding two- and three-point correlation functions are presented at all energy scales. These give access to the properties of the gauge bosons, like their absence from the asymptotic physical state space, the absence of an on-shell mass pole, particle-like properties at high energies, and their running couplings. Furthermore, auxiliary degrees of freedom are introduced during gauge-fixing, and their properties are discussed as well. These results are presented for two, three, and four dimensions, and for various gauge algebras. Finally, the modifications of the properties of gauge bosons at finite temperature are presented. Evidence is provided that these reflect the phase structure of Yang-Mills theory. However, it is found that the phase transition is not deconfining the gauge bosons, although the bulk thermodynamical behavior is of a Stefan-Boltzmann type. The resolution of this apparent contradiction is also presented. This resolution also provides an explicit and constructive solution to the Linde problem."



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[1309.1957] Analytic and numerical study of the free energy in gauge theory

[1309.1957] Analytic and numerical study of the free energy in gauge theory:



 "We derive some exact bounds on the free energy W(J) in an SU(N) gauge theory, where J_mu^b is a source for the gluon field A_mu^b in the minimal Landau gauge, and W(J) is the generating functional of connected correlators, exp W(J) = . We also provide asymptotic expressions for the free energy W(J) at large J and for the quantum effective action Gamma(A) at large A. We specialize to a source J(x)=h cos(kx) of definite momentum k and source strength h, and study the gluon propagator D(k,h) in the presence of this source. Among other relations, we prove int_0^inf dh D(k,h)<=2^1/2 k, which implies lim_(k->0) D(k,h) = 0, for all positive h>0. Thus the system does not respond to a static color probe, no matter how strong. Recent lattice data in minimal Landau gauge in d =3 and 4 dimensions at h=0 indicate that the gluon propagator in the minimum Landau gauge is finite, lim_(k->0) D(k,0)>0. Thus these lattice data imply a jump in the value of D(k,h) at h=0 and k=0, and the value of D(k,h) at this point depends on the order of limits. We also present numerical evaluations of the free energy W(k,h) and the gluon propagator D(k,h) for the case of SU(2) Yang-Mills theory in various dimensions which support all of these findings."



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The Libertarian Fantasy - NYTimes.com

The Libertarian Fantasy - NYTimes.com:



 "In the latest Times Magazine, Robert Draper profiled youngish libertarians — roughly speaking, people who combine free-market economics with permissive social views — and asked whether we might be heading for a “libertarian moment.” Well, probably not. Polling suggests that young Americans tend, if anything, to be more supportive of the case for a bigger government than their elders. But I’d like to ask a different question: Is libertarian economics at all realistic?"



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The Empiricist Strikes Back - NYTimes.com

The Empiricist Strikes Back - NYTimes.com:



"If climate change doesn’t scare you, and our failure to act doesn’t inspire despair, you’re not paying attention. And the great sin of the climate deniers is their role in delaying action, quite possibly until it’s too late.

But there are other, smaller evils; and one that strikes close to home for me is the campaign of personal destruction waged against Michael Mann.

Mann, as some of you may know, is a hard-working scientist who used indirect evidence from tree rings and ice cores in an attempt to create a long-run climate record.



His result was the famous “hockey stick” of sharply rising temperatures in the age of industrialization and fossil fuel consumption. His reward for that hard work was not simply assertions that he was wrong — which he wasn’t — but a concerted effort to destroy his life and career with accusations of professional malpractice, involving the usual suspects on the right but also public officials, like the former Attorney General of Virginia.

As you can imagine, I find it easy to put myself in Mann’s shoes; obviously a lot of people would like to do something similar to me, although they haven’t (yet?) found a suitable line of attack.

Now for the slightly encouraging news: Mann filed suit against National Review for defamation.



 And as D.R. Tucker points out at Washington Monthly, the latest response from NR sounds very much like a publication running scared.

Also encouraging is the evident inability of NR to understand how you defend against a charge of defamation. You don’t repeat the false allegations — sorry, guys, but courts also have access to Google and Nexis, and can find that all the charges have been rejected in repeated inquiries.



You try, instead, to show that you made the allegations in good faith. But of course they didn’t.



 Good for Mann in standing up here; he’s doing all of us a service."



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Garry Kasparov, the Man Who Would Be King - NYTimes.com

Garry Kasparov, the Man Who Would Be King - NYTimes.com:



 "Garry Kasparov, the former world chess champion, put his head down, hunched his shoulders and walked hurriedly down the carpeted corridor of the Sands Cotai Central, a labyrinthine new complex on reclaimed land in Macau. Downstairs were two of the world’s most lucrative casinos and retailers like Saint Laurent Paris and Fabio Caviglia. There were restaurants, spas and an array of theme-park attractions from DreamWorks, including a daily parade through the lobby with characters from “Shrek,” “Madagascar” and “Kung Fu Panda.” Here on the fourth floor, though, hundreds of boys and girls from across Asia had just wrapped up their matches in a chess tournament. Spilling into the corridor, many of them gaped at Kasparov barreling by, as if Shrek himself had wandered up to the wrong floor. That was why he was rushing, he explained, when I managed to catch up to him as he turned toward a bank of elevators. “If you stop,” he said, “you’ll be there for 30 minutes.” He did not sound angry, just matter of fact. “Everyone circles around. They want pictures.”"



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Why the 3D Writhe of Alternating Knots and Links Is Quantized and Additive

Why the 3D Writhe of Alternating Knots and Links Is Quantized and Additive:



"Besides mathematical interest, knots and knot theory have important applications in physics, chemistry, and biology. Stasiak and colleagues devised a constructive method for a knot "energy" using a Metropolis Monte Carlo algorithm to minimize the length of rope needed to realize a given knot for a rope of fixed diameter. They called the resulting rendering of the knot the "ideal" configuration. They have found (i) that the 3-dimensional (3D) writhe of the ideal configuration of a knot appeared, empirically, to be quantized; (ii) empirically, the 3D writhe of the ideal configuration was additive over composition of knots; and (iii) the 3D writhe of the ideal configuration of alternating knots (which have a projection in which crossings alternate between over and under as one traverses the knot in a fixed direction) seems to be equal, to 1*T + 3/7*(W-B), where T is the "Tait number," and W and B are the number of white and black regions in the checkerboard coloring of the knot. It is still not clear why properties i-iii might be true. Here I show that all these empirical findings can be related to the fact that T and W-B can be proven to be additive over composition of alternating knots. In particular, (1) the 3D writhe of ideal configurations is likely only to be additive for composition of alternating knots, and (2) remarkably, the geometrical structure of all alternating (even prime) knots is determined by the three smallest knots."



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Writhe - Wikipedia, the free encyclopedia

Writhe - Wikipedia, the free encyclopedia:



 "In knot theory, there are several competing notions of the quantity writhe, or Wr. In one sense, it is purely a property of an oriented link diagram and assumes integer values. In another sense, it is a quantity that describes the amount of "coiling" of a mathematical knot (or any closed, simple curve) in three-dimensional space and assumes real numbers as values. In both cases, writhe is a geometric quantity, meaning that while deforming a curve (or diagram) in such a way that does not change its topology, one may still change its writhe.[1]"



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Bank of America Offers U.S. Biggest Settlement in History - NYTimes.com

Bank of America Offers U.S. Biggest Settlement in History - NYTimes.com:



"After months of lowball offers and heels dug in, it took only 24 hours for Bank of America to suddenly cave in to the government, agreeing to the largest single federal settlement in the history of corporate America."



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