| Records |
Author  |
Van Isacker, P.; Algora, A.; Vitéz-Sveiczer, A.; Kiss, G.G.; Orrigo, S.E.A.; Rubio, B.; Aguilera, P. |
| Title |
Gamow-Teller Beta Decay and Pseudo-SU(4) Symmetry |
Type |
Journal Article |
| Year |
2023 |
Publication |
Symmetry-Basel |
Abbreviated Journal |
Symmetry-Basel |
| Volume |
15 |
Issue |
11 |
Pages |
2001 - 15pp |
| Keywords |
Gamow-Teller beta decay; pseudo-SU(4) symmetry; odd-odd N = Z nuclei |
| Abstract |
We report on recent experimental results on beta decay into self-conjugate ( N = Z) nuclei with mass number 58 <= A <= 70. Super-allowed b decays from the J(pi) = 0(+) ground state of a Z = N + 2 parent nucleus are to the isobaric analogue state through so-called Fermi transitions and to J(pi) = 1(+) states by way of Gamow-Teller (GT) transitions. The operator of the latter decay is a generator of Wigner's SU(4) algebra and as a consequence GT transitions obey selection rules associated with this symmetry. Since SU(4) is progressively broken with increasing A, mainly as a consequence of the spinorbit interaction, this symmetry is not relevant for the nuclei considered here. We argue, however, that the pseudo-spin-orbit splitting can be small in nuclei with 58 <= A <= 70, in which case nuclear states exhibit an approximate pseudo-SU(4) symmetry. To test this conjecture, GT decay strength is calculated with use of a schematic Hamiltonian with pseudo-SU(4) symmetry. Some generic features of the GT beta decay due to pseudo-SU(4) symmetry are pointed out. The experimentally observed GT strength indicates a restoration of pseudo-SU(4) symmetry for A = 70. |
| Address |
[Van Isacker, Piet] CEA, DRF, Grand Accelerateur Natl Ions Lourds GANIL, CNRS,IN2P3, Blvd Henri Becquerel, F-14076 Caen, France, Email: isacker@ganil.fr; |
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| Publisher |
Mdpi |
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| Language |
English |
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Expedition |
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Conference |
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| Notes |
WOS:001114520800001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5843 |
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| Author |
van Beekveld, M.; Caron, S.; Ruiz de Austri, R. |
| Title |
The current status of fine-tuning in supersymmetry |
Type |
Journal Article |
| Year |
2020 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
01 |
Issue |
1 |
Pages |
147 - 41pp |
| Keywords |
Supersymmetry Phenomenology |
| Abstract |
In this paper, we minimize and compare two different fine-tuning measures in four high-scale supersymmetric models that are embedded in the MSSM. In addition, we determine the impact of current and future dark matter direct detection and collider experiments on the fine-tuning. We then compare the low-scale electroweak measure with the high-scale Barbieri-Giudice measure. We find that they reduce to the same value when the higgsino parameter drives the degree of fine-tuning. We also find spectra where the high-scale measure turns out to be lower than the low-scale measure. Depending on the high-scale model and fine-tuning definition, we find a minimal fine-tuning of 3-38 (corresponding to O(10-1)%) for the low-scale measure, and 63-571 (corresponding to O(1-0.1)%) for the high-scale measure. We stress that it is too early to conclude on the fate of supersymmetry, based only on the fine-tuning paradigm. |
| Address |
[van Beekveld, Melissa; Caron, Sascha] Radboud Univ Nijmegen, Theoret High Energy Phys, Heyendaalseweg 135, NL-6525 AJ Nijmegen, Netherlands, Email: mcbeekveld@gmail.com; |
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| Publisher |
Springer |
Place of Publication |
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English |
Summary Language |
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Edition |
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| ISSN |
1029-8479 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000512011100001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4275 |
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| Author |
van Beekveld, M.; Caron, S.; Hendriks, L.; Jackson, P.; Leinweber, A.; Otten, S.; Patrick, R.; Ruiz de Austri, R.; Santoni, M.; White, M. |
| Title |
Combining outlier analysis algorithms to identify new physics at the LHC |
Type |
Journal Article |
| Year |
2021 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
| Volume |
09 |
Issue |
9 |
Pages |
024 - 33pp |
| Keywords |
Phenomenological Models; Supersymmetry Phenomenology |
| Abstract |
The lack of evidence for new physics at the Large Hadron Collider so far has prompted the development of model-independent search techniques. In this study, we compare the anomaly scores of a variety of anomaly detection techniques: an isolation forest, a Gaussian mixture model, a static autoencoder, and a beta-variational autoencoder (VAE), where we define the reconstruction loss of the latter as a weighted combination of regression and classification terms. We apply these algorithms to the 4-vectors of simulated LHC data, but also investigate the performance when the non-VAE algorithms are applied to the latent space variables created by the VAE. In addition, we assess the performance when the anomaly scores of these algorithms are combined in various ways. Using supersymmetric benchmark points, we find that the logical AND combination of the anomaly scores yielded from algorithms trained in the latent space of the VAE is the most effective discriminator of all methods tested. |
| Address |
[van Beekveld, Melissa] Clarendon Lab, Rudolf Peierls Ctr Theoret Phys, 20 Pks Rd, Oxford OX1 3PU, England, Email: mcbeekveld@gmail.com; |
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| Publisher |
Springer |
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| Language |
English |
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Edition |
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| ISSN |
1029-8479 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000695421600003 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
4973 |
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| Author |
van Beekveld, M.; Beenakker, W.; Caron, S.; Kip, J.; Ruiz de Austri, R.; Zhang, Z.Y. |
| Title |
Non-standard neutrino spectra from annihilating neutralino dark matter |
Type |
Journal Article |
| Year |
2023 |
Publication |
Scipost Physics Core |
Abbreviated Journal |
SciPost Phys. Core |
| Volume |
6 |
Issue |
1 |
Pages |
006 - 23pp |
| Keywords |
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| Abstract |
Neutrino telescope experiments are rapidly becoming more competitive in indirect de-tection searches for dark matter. Neutrino signals arising from dark matter annihilations are typically assumed to originate from the hadronisation and decay of Standard Model particles. Here we showcase a supersymmetric model, the BLSSMIS, that can simulta-neously obey current experimental limits while still providing a potentially observable non-standard neutrino spectrum from dark matter annihilation. |
| Address |
[van Beekveld, Melissa] Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Clarendon Lab, Parks Rd, Oxford OX1 3PU, England, Email: melissa.vanbeekveld@physics.ox.ac.uk; |
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| Publisher |
Scipost Foundation |
Place of Publication |
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English |
Summary Language |
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Expedition |
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Conference |
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| Notes |
WOS:000928492200001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
5480 |
| Permanent link to this record |
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| Author |
Valiente-Dobon, J.J.; Poves, A.; Gadea, A.; Fernandez-Dominguez, B. |
| Title |
Broken mirror symmetry in S-36 and Ca-36 |
Type |
Journal Article |
| Year |
2018 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
| Volume |
98 |
Issue |
1 |
Pages |
011302 - 5pp |
| Keywords |
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| Abstract |
Shape coexistence is a ubiquitous phenomenon in the neutron-rich nuclei belonging to (or sitting at the shores of) the N = 20 island of inversion (IoI). Exact isospin symmetry predicts the same behavior for their mirrors and the existence of a proton-rich IoI around Z = 20, centered in the (surely unbound) nucleus Ca-32. In this article we show that in Ca-36 and S-36, Coulomb effects break dramatically the mirror symmetry in the excitation energies due to the different structures of the intruder and normal states. The mirror energy difference (MED) of their 2(+) states is known to be very large at – 246 keV. We reproduce this value and predict the first excited state in Ca-36 to be a 0(+) at 2.7 MeV, 250 keV below the first 2(+). In its mirror S-36 the 0(+) lies at 55keV above the 2(+) measured at 3.291 MeV. Our calculations predict a huge MED of -720 keV, that we dub the “colossal” mirror energy difference. A possible reaction mechanism to access the O-2(+) in Ca-36 will be discussed. In addition, we theoretically address the MEDs of the A = 34, T = 3 and A = 32, T = 4 mirrors. |
| Address |
[Valiente-Dobon, J. J.] Ist Nazl Fis Nucl, Lab Nazl Legnaro, Legnaro, Italy |
| Corporate Author |
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Thesis |
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| Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
2469-9985 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
WOS:000439059400001 |
Approved |
no |
| Is ISI |
yes |
International Collaboration |
yes |
| Call Number |
IFIC @ pastor @ |
Serial |
3661 |
| Permanent link to this record |
