| 1. |
- Catena, Riccardo, 1978, et al.
(författare)
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Dark matter-electron interactions in materials beyond the dark photon model
- 2023
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; 2023:3
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Tidskriftsartikel (refereegranskat)abstract
- The search for sub-GeV dark matter (DM) particles via electronic transitions in underground detectors attracted much theoretical and experimental interest in the past few years. A still open question in this field is whether experimental results can in general be interpreted in a framework where the response of detector materials to an external DM probe is described by a single ionisation or crystal form factor, as expected for the so-called dark photon model. Here, ionisation and crystal form factors are examples of material response functions: interaction-specific integrals of the initial and final state electron wave functions. In this work, we address this question through a systematic classification of the material response functions induced by a wide range of models for spin-0, spin-1/2 and spin-1 DM. We find several examples for which an accurate description of the electronic transition rate at DM direct detection experiments requires material response functions that go beyond those expected for the dark photon model. This concretely illustrates the limitations of a framework that is entirely based on the standard ionisation and crystal form factors, and points towards the need for the general response-function-based formalism we pushed forward recently [1,2]. For the models that require non-standard atomic and crystal response functions, we use the response functions of [1,2] to calculate the DM-induced electronic transition rate in atomic and crystal detectors, and to present 90% confidence level exclusion limits on the strength of the DM-electron interaction from the null results reported by XENON10, XENON1T, EDELWEISS and SENSEI.
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| 2. |
- Lu, Hsuan Hao, et al.
(författare)
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Simulations of subatomic many-body physics on a quantum frequency processor
- 2019
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Ingår i: Physical Review A. - 2469-9934 .- 2469-9926. ; 100:1
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Tidskriftsartikel (refereegranskat)abstract
- Simulating complex many-body quantum phenomena is a major scientific impetus behind the development of quantum computing, and a range of technologies are being explored to address such systems. We present the results of the largest photonics-based simulation to date, applied in the context of subatomic physics. Using an all-optical quantum frequency processor, the ground-state energies of light nuclei including the triton (H3), He3, and the alpha particle (He4) are computed. Complementing these calculations and utilizing a 68-dimensional Hilbert space, our photonic simulator is used to perform subnucleon calculations of the two- and three-body forces between heavy mesons in the Schwinger model. This work is a first step in simulating subatomic many-body physics on quantum frequency processors - augmenting classical computations that bridge scales from quarks to nuclei.
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| 3. |
- Lestinsky, M., et al.
(författare)
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Physics book: CRYRING@ESR
- 2016
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Ingår i: European Physical Journal: Special Topics. - : Springer Science and Business Media LLC. - 1951-6401 .- 1951-6355. ; 225:5, s. 797-882
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Forskningsöversikt (refereegranskat)abstract
- The exploration of the unique properties of stored and cooled beams of highly-charged ions as provided by heavy-ion storage rings has opened novel and fascinating research opportunities in the realm of atomic and nuclear physics research. Since the late 1980s, pioneering work has been performed at the CRYRING at Stockholm (Abrahamsson et al. 1993) and at the Test Storage Ring (TSR) at Heidelberg (Baumann et al. 1988). For the heaviest ions in the highest charge-states, a real quantum jump was achieved in the early 1990s by the commissioning of the Experimental Storage Ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung (GSI) in Darmstadt (Franzke 1987) where challenging experiments on the electron dynamics in the strong field regime as well as nuclear physics studies on exotic nuclei and at the borderline to atomic physics were performed. Meanwhile also at Lanzhou a heavy-ion storage ring has been taken in operation, exploiting the unique research opportunities in particular for medium-heavy ions and exotic nuclei (Xia et al. 2002).
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| 4. |
- Forssen, Christian, 1974, et al.
(författare)
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The Ab Initio No-core Shell Model
- 2009
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Ingår i: Few-Body Systems. - : Springer Science and Business Media LLC. - 1432-5411 .- 0177-7963. ; 45:2, s. 111-
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Konferensbidrag (refereegranskat)abstract
- This contribution reviews a number of applications of the ab initio no-core shell model (NCSM) within nuclear physics and beyond. We will highlight a nuclear-structure study of the A = 12 isobar using a chiral NN + 3NF interaction. In the spirit of this workshop we will also mention the new development of the NCSM formalism to describe open channels and to approach the problem of nuclear reactions. Finally, we will illustrate the universality of the many-body problem by presenting the recent adaptation of the NCSM effective-interaction approach to study the many-boson problem in an external trapping potential with short-range interactions.This article is based on the presentation by C. Forssén at the Fifth Workshop on Critical Stability, Erice, Sicily.
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| 5. |
- Tornsö, Marcus, 1993
(författare)
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Holographic descriptions of collective modes in strongly correlated media
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Solving the puzzle of high temperature superconductivity may be one of the most desired scientific breakthroughs of our time, as access to room temperature superconductivity could revolutionize society as we know it. In this thesis, we strive to increase the theoretical understanding of such matter, by studying the phase above, in temperature, the superconducting phase - the "strange metal". The strange metal phase is a phase characterized by the absence of a quasi-particle description. The electrons in this phase are strongly coupled, which means that conventional methods, such as perturbation theory in quantum field theory and Monte Carlo methods fall short of being able to describe their dynamics. Perhaps surprisingly, string theory provides a different method, capable of describing precisely such systems - the holographic duality. Whereas there has been significant effort devoted to the applications of the duality since its inception in 1997, and even more so in the last decade after it was observed that it worked remarkably well for condensed matter theory, it wasn't until our project that the dynamical polarization of such strongly coupled systems where properly treated. In this thesis, we introduce the minimal constraints required for a sensible description of a polarizing medium, and convert those to boundary conditions to the equations of motion provided by the holographic dual. These boundary conditions deviate from previous holographic studies, and we contrast the quasinormal modes previously studied with the emergent collective modes we find for some different models. We find novel results, as well as confirm the predictions of less general models in their respective regions of validity and pave the way for more complex future models.
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| 6. |
- Borsato, M., et al.
(författare)
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Unleashing the full power of LHCb to probe stealth new physics
- 2022
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Ingår i: Reports on Progress in Physics. - : IOP Publishing. - 0034-4885 .- 1361-6633. ; 85:2
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we describe the potential of the LHCb experiment to detect stealth physics. This refers to dynamics beyond the standard model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.
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| 7. |
- Cederwall, Martin, 1961
(författare)
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An off-shell superspace reformulation of D=4, N=4 super-Yang–Mills theory
- 2017
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- D = 4, N = 4 super-Yang-Mills theory has an off-shell superspace formulation in terms of pure spinor superfields, which is directly inherited from the D = 10 theory. That superspace, in particular the choice of pure spinor variables, is less suitable for dealing with fields that are inherently 4-dimensional, such as the superfields based on the scalars, which are gauge-covariant, and traces of powers of scalars, which are gauge-invariant. We give a reformulation of D = 4, N = 4 super-Yang-Mills theory in N = 4 superspace, using inherently 4-dimensional pure spinors. All local degrees of freedom reside in a superfield based on the physical scalars. The formalism should be suited for calculations of correlators of traces of scalar superfields.
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| 8. |
- Pazsit, Imre, 1948
(författare)
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A random walk in reactor physics and neutron transport
- 2020
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Ingår i: J. Reactor Phys. Section of AESJ. ; 72:3, s. 1-12
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The title of this paper alludes to two different meanings of “random”. First, the phrase “Random walk” refers to the fact that I selected, at random, a few topics which I myself found fascinating, surprising, and hence hopefully entertaining, in the hope that the reader will also find them entertaining. The phenomena that will be described and discussed here will reveal some unexpected features, which in some cases are puzzling or even counter-intuitive, and their explanation sometimes discloses commonly accepted misbeliefs or misunderstandings. I always found such cases very intriguing. Inevitably, such subjects do not constitute a continuous story, rather they are picked randomly, hence the first meaning of the phrase “random walk” in the title. Curiosities similar to the types that will be discussed in this note are usually published as a “Letter to the Editor” or a “Technical Note”, since they do not contain new research results. A few examples are given in Ref [1] (meaning of the flux) and Refs [2] - [4] (number of collisions until slowing down). The readers are encouraged to check up these letters or technical notes. Many are, in contrast to the present article, quite short, often only one page, hence the “output/input ratio” in intellectual entertainment is quite high. I can also recommend the readers to watch out for such short notes by themselves (although, sadly, the number of such notes seems to be decreasing). The second reason why the word “random” appears in the title is because the curious facts and phenomena which will be discussed here concern the randomness of neutron transport, manifesting itself in the fact that the number of neutrons in the system, or the number of detector counts during a time period, is a random number or random process (hence often referred to as neutron fluctuations or neutron noise). Random processes in general, whether about neutrons or other processes, have themselves fascinating and surprising properties. The subjects discussed in this small essay will hopefully also expedite a wider understanding of the properties and use of neutron fluctuations in nuclear systems. With this introduction, I invite the reader to follow me on the random walk in the fascinating world of random particle transport.
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| 9. |
- Aalbers, J., et al.
(författare)
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A next-generation liquid xenon observatory for dark matter and neutrino physics
- 2023
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 50:1
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Forskningsöversikt (refereegranskat)abstract
- The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.
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| 10. |
- Johannesson, Henrik, 1953, et al.
(författare)
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Conformal field theory approach to the two-channel Anderson model
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:SUPPL. 1
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Tidskriftsartikel (refereegranskat)abstract
- The two-channel Anderson impurity model serves as a prototype for describing heavy-fermion materials with a possible mixed-valent regime with both quadrupolar and magnetic character. We report on the low-energy physics of the model, using a conformal field theory approach with exact Bethe Ansatz results as input.
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