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Roland E. Allen

Publications and source records attributed to Roland E. Allen.

At least 19 recordsLinked to original sources

The cosmological constant, dark matter, and other unsolved problems from a fresh perspective

Quantum theory, general relativity, the standard model of particle physics, and the $Λ$CDM model of cosmology have all been spectacularly successful within their respective regimes of applicability, but many central problems remain unsolved. Here we propose a fresh perspective on these problems, based on a description which has elements in common with other efforts toward a fundamental theory, since it also is based on higher dimensions (with an internal space), a form of supersymmetry, important topological structures, and the implication of a multiverse: Our universe is topologically stable because it contains the product of two vortex-like (or instanton-like) configurations of a primordial condensate -- one in 4-dimensional external spacetime, with the big bang at its origin, and the second in a 10-dimensional internal space which yields an SO(10) gauge theory. A third 3-dimensional internal space yields family replication. The arguments leading up to and following this basic picture imply a radically modified view of many unsolved problems and related issues, including the absence of an enormous cosmological constant, the nature of dark matter, the origin of supersymmetry, the origin of Lorentz invariance, the origin of gravitational and gauge interactions, the gravitational metric and its signature, the fundamental action for fermionic and bosonic fields, the regularization of quantum gravity, the origin of quantum fields, the origin of spacetime coordinates, the entropy of black holes, and the probability interpretation of quantum mechanics. Among other near-term predictions, the calculations of Tallman et al. for the dark matter WIMP based on these ideas show that it should be observable at the high-luminosity LHC, nominally at the 5$σ$ level with 500 fb$^{-1}$ of integrated luminosity, and it may already have been observed by Fermi-LAT and AMS-02.

physics.gen-ph

Experimental signatures of an alternative supersymmetry

There are at least three physical arguments for some form of supersymmetry, based on experiment and observation, but conventional supersymmetry (SUSY) has not been observed up to surprisingly high experimental limits. Here we consider a radically different version, with initial bosonic fields in $32=16+\overline{16}$ (primitive sfermion) and $10=5+\overline{5}$ (primitive Higgs-related) representations of Spin(10) which do not satisfy Lorentz invariance. In the extremely early universe there is a reformation of these fields to achieve a stable Lorentz-invariant vacuum with two varieties of physical scalar-boson fields -- standard fields $ϕ$ and fields $φ$ of a new kind. There are then two possible scenarios: If sfermion fields are in the $ϕ$ sector, the present description leads back to standard physics, including the standard model, SO(10) grand unification, and conventional SUSY. But if sfermion fields belong to the $φ$ sector, the predictions for production and decays of sparticles are dramatically different, potentially explaining their previous nonobservation. The masses of scalar bosons are still protected from enormous radiative corrections, gauge unification can be achieved, and there is a lowest-mass superpartner as a dark matter candidate -- although it is presumed to be less abundant than the $\approx 70$ GeV candidate we introduced earlier in this same general context. Calculations by Shankar, Tallman, and Martinez in separate papers explore the possibilities for detection in future colliders, beginning with the high-luminosity LHC.

physics.gen-ph

Cross-sections and experimental signatures for detection of a well-defined dark matter WIMP

We report the following calculations for a recently proposed bosonic dark matter WIMP with well-defined interactions: (1)~the mass as determined by fitting to the relic abundance; (2)~the current annihilation cross-section for indirect detection; (3)~cross-sections for pair production accompanied by jets in proton colliders with center-of-mass energies ranging from 13 to 100 TeV; (4)~for the high-luminosity LHC, and planned 100 TeV proton collider, detailed plots of experimentally accessible quantities before and after optimal cuts; (5)~cross-sections, and plots of experimentally accessible quantities, for production in e$^+$e$^-$ or muon colliders with center-of-mass energies up to 10 TeV; (6)~cross-section per nucleon for direct detection. The conclusions are given in the text, including the principal prediction that (with optimal cuts) this particle should be detectable at the high-luminosity LHC, perhaps after only two years with an integrated luminosity of 500 fb$^{-1}$.

hep-ph

Predictions of a fundamental statistical picture

The discovery of a Higgs boson at the electroweak scale appears to point toward supersymmetry, as the most likely mechanism for protecting a scalar boson mass from enormous radiative corrections. The earlier discovery of neutrino masses similarly appears to point toward grand unification of nongravitational forces, which permits (for neutrinos) Majorana masses, Dirac masses, and a seesaw mechanism to drive the observed masses down to low values. A third major discovery, cosmic acceleration suggesting a relatively tiny cosmological constant, appears to point toward truly revolutionary new physics. Many other problems and mysteries also indicate a need for fresh ideas at the most fundamental level. Here a picture is proposed in which standard physics and its extensions are obtained (through a nontrivial set of arguments) from statistical counting and the local geography of our universe. The unavoidable predictions include supersymmetry (at some energy scale), SO(N) grand unification, a drastic diminishing of the usual cosmological constant, and a nonsupersymmetric dark matter WIMP which should be detectable within the next several years.

hep-th

A dark matter WIMP that can be detected and definitively identified with currently planned experiments

A recently proposed dark matter WIMP has only second-order couplings to gauge bosons and itself. As a result, it has small annihilation, scattering, and creation cross-sections, and is consequently consistent with all current experiments and the observed abundance of dark matter. These cross-sections are, however, still sufficiently large to enable detection in experiments that are planned for the near future, and definitive identification in experiments proposed on a longer time scale. The (multi-channel) cross-section for annihilation is consistent with thermal production and freeze-out in the early universe, and with current evidence for dark matter annihilation in analyses of the observations of gamma rays by Fermi-LAT and antiprotons by AMS-02, as well as the constraints from Planck and Fermi-LAT. The cross-section for direct detection via collision with xenon nuclei is estimated to be slightly below $10^{-47}$ cm$^2$, which should be attainable by LZ and Xenon nT and well within the reach of Darwin. The cross-section for collider detection via vector boson fusion is estimated to be $\sim 1$ fb, and may be ultimately attainable by the high-luminosity LHC; definitive collider identification will probably require the more powerful facilities now being proposed.

hep-ph

Experimental signatures of a new dark matter WIMP

The WIMP proposed here yields the observed abundance of dark matter, and is consistent with the current limits from direct detection, indirect detection, and collider experiments, if its mass is $\sim 72$ GeV/$c^2$. It is also consistent with analyses of the gamma rays observed by Fermi-LAT from the Galactic center (and other sources), and of the antiprotons observed by AMS-02, in which the excesses are attributed to dark matter annihilation. These successes are shared by the inert doublet model (IDM), but the phenomenology is very different: The dark matter candidate of the IDM has first-order gauge couplings to other new particles, whereas the present candidate does not. In addition to indirect detection through annihilation products, it appears that the present particle can be observed in the most sensitive direct-detection and collider experiments currently being planned.

hep-ph

The sounds of science: a symphony for many instruments and voices

This paper is a celebration of the frontiers of science. Goodenough, the maestro who transformed energy usage and technology through the invention of the lithium ion battery, opens the programme, reflecting on the ultimate limits of battery technology. This applied theme continues through the subsequent pieces on energy related topics (the sodium ion battery and artificial fuels, by Mansson) and the ultimate challenge for 3 dimensional printing the eventual production of life, by Atala. A passage by Alexander follows, reflecting on a related issue: How might an artificially produced human being behave? Next comes a consideration of consiousness and free will by Allen and Lidstrom. Further voices and new instruments enter as Bowen, Mauranyapin and Madsen discuss whether dynamical processes of single molecules might be observed in their native state. The exploitation of chaos in science and technology, applications of Bose Einstein condensates and a consideration of the significance of entropy follow in pieces by Reichl, Rasel and Allen, respectively. Katsnelson and Koonin then discuss the potential generalisation of thermodynamic concepts in the context of biological evolution. Entering with the music of the cosmos, Yasskin discusses whether we might be able to observe torsion in the geometry of the universe. The crescendo comes with the crisis of singularities, their nature and whether they can be resolved through quantum effects, in the composition of Coley. The climax is Krenn, Melvin and Zeilinger consideration of how computer code can be autonomously surprising and creative. In a harmonious counterpoint, Yampolskiy concludes that such code is not yet able to take responsibility for coauthoring a paper.

physics.pop-ph

Black hole entropy, the black hole information paradox, and time travel paradoxes from a new perspective

Relatively simple but apparently novel ways are proposed for viewing three related subjects: black hole entropy, the black hole information paradox, and time travel paradoxes. (1) Gibbons and Hawking have completely explained the origin of the entropy of all black holes, including physical black holes -- nonextremal and in 3-dimensional space -- if one can identify their Euclidean path integral with a true thermodynamic partition function (ultimately based on microstates). An example is provided of a theory containing this feature. (2) There is unitary quantum evolution with no loss of information if the detection of Hawking radiation is regarded as a measurement process within the Everett interpretation of quantum mechanics. (3) The paradoxes of time travel evaporate when exposed to the light of quantum physics (again within the Everett interpretation), with quantum fields properly described by a path integral over a topologically nontrivial but smooth manifold.

physics.gen-ph

Two natural scenarios for dark matter particles coexisting with supersymmetry

We describe two natural scenarios in which both dark matter WIMPs (weakly interacting massive particles) and a variety of supersymmetric partners should be discovered in the foreseeable future. In the first scenario, the WIMPs are neutralinos, but they are only one component of the dark matter, which is dominantly composed of other relic particles such as axions. (This is the multicomponent model of Baer, Barger, Sengupta, and Tata.) In the second scenario, the WIMPs result from an extended Higgs sector and may be the only dark matter component. In either scenario, both the dark matter WIMP and a plethora of other neutral and charged particles await discovery at many experimental facilities. The new particles in the second scenario have far weaker cross-sections for direct and indirect detection via their gauge interactions, which are either momentum-dependent or second-order. However, as we point out here, they should have much stronger interactions via the Higgs. We estimate that their interactions with fermions will then be comparable to (although not equal to) those of neutralinos with a corresponding Higgs interaction. It follows that these newly proposed dark matter particles should be within reach of emerging and proposed facilities for direct, indirect, and collider-based detection.

hep-ph

Time-dependent Ginzburg-Landau model for light-induced superconductivity in the cuprate LESCO

Cavalleri and coworkers have discovered evidence of light-induced superconductivity and related phenomena in several different materials. Here we suggest that some features may be naturally interpreted using a time-dependent Ginzburg-Landau model. In particular, we focus on the lifetime of the transient state in La$_{1.675}$Eu$_{0.2}$Sr$_{0.125}$CuO$_4$ (LESCO$_{1/8}$), which is remarkably long below about 25 K, but exhibits different behavior at higher temperature.

cond-mat.supr-con

Life, the universe, and everything - 42 fundamental questions

In The Hitchhiker's Guide to the Galaxy, by Douglas Adams, the Answer to the Ultimate Question of Life, the Universe, and Everything is found to be 42 -- but the meaning of this is left open to interpretation. We take it to mean that there are 42 fundamental questions which must be answered on the road to full enlightenment, and we attempt a first draft (or personal selection) of these ultimate questions, on topics ranging from the cosmological constant and origin of the universe to the origin of life and consciousness.

physics.pop-ph

Dark matter candidate with well-defined mass and couplings

We propose a Higgs-related but spin $1/2$ dark matter candidate with a mass that is comparable to that of the Higgs. This particle is a WIMP with an R-parity of $-1$, but it can be distinguished from a neutralino by its unconventional couplings to W and Z bosons. Charged spin 1/2 particles of a new kind are also predicted at higher energy.

hep-ph

Predicted Higgs-related spin 1/2 particles as a new dark matter candidate

The theory at arXiv:1101.0586 [hep-th] predicts new fundamental spin $1/2$ particles which can be produced in pairs through their couplings to vector bosons or fermions. The lowest-energy of these should have a mass $m_{1/2}$ comparable to the mass $m_h$ of the recently discovered Higgs boson, with $m_{1/2} = m_h$ in the simplest model. These particles should therefore be detectable in collider experiments, perhaps in Run 2 or 3 of the LHC. They cannot decay through any obvious mechanisms in standard physics, making them a new dark matter candidate. In the simplest model, annihilations would produce a well-defined signature with photons, positrons, and excess electrons at about 125 GeV, and the mass would also be well-defined for direct dark matter detection.

hep-ph

The Higgs Bridge

The particle recently discovered at the Large Hadron Collider near Geneva is almost certainly a Higgs boson, the long-sought completion of the Standard Model of particle physics. But this discovery, an achievement by more than six thousand scientists (including students), is actually much more than a mere capstone of the Standard Model. It instead represents a bridge from the Standard Model to exciting discoveries of the future, at higher energies or in other experiments, and to the properties of matter at very low temperatures. The mere existence of a particle with zero spin implies a need for new physics, with the most likely candidate being supersymmetry, which requires that every known particle has a superpartner yet to be discovered. And phenomena similar to the Higgs are seen in superconducting metals and superfluid gases at low temperatures, which extend down to a millionth or even a billionth of a degree Kelvin. So the discovery of a Higgs boson has a central place in our attempts both to achieve a true understanding of Nature and to harness Nature in practical applications.

hep-ph

The London-Anderson-Englert-Brout-Higgs-Guralnik-Hagen-Kibble-Weinberg mechanism and Higgs boson reveal the unity and future excitement of physics

The particle recently discovered by the CMS and ATLAS collaborations at CERN is almost certainly a Higgs boson, fulfilling a quest that can be traced back to three seminal high energy papers of 1964, but which is intimately connected to ideas in other areas of physics that go back much further. One might oversimplify the history of the features which (i) give mass to the W and Z particles that mediate the weak nuclear interaction, (ii) effectively break gauge invariance, (iii) eliminate physically unacceptable Nambu-Goldstone bosons, and (iv) give mass to fermions (like the electron) by collectively calling them the London-Anderson-Englert-Brout-Higgs-Guralnik-Hagen-Kibble-Weinberg mechanism. More important are the implications for the future: a Higgs boson appears to point toward supersymmetry, since new physics is required to protect its mass from enormous quantum corrections, while the discovery of neutrino masses seems to point toward grand unification of the nongravitational forces.

hep-ph

Maximum relative excitation of a specific vibrational mode via optimum laser pulse duration

For molecules and materials responding to femtosecond-scale optical laser pulses, we predict maximum relative excitation of a Raman-active vibrational mode with period T when the pulse has an FWHM duration of 0.42 T. This result follows from a general analytical model, and is precisely confirmed by detailed density-functional-based dynamical simulations for C60 and a carbon nanotube, which include anharmonicity, nonlinearity, no assumptions about the polarizability tensor, and no averaging over rapid oscillations within the pulse. The mode specificity is, of course, best at low temperature and for pulses that are electronically off-resonance, and the energy deposited in any mode is proportional to the fourth power of the electric field.

cond-mat.mes-hall