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BETA
Ohlsson, Tommy, ProfessorORCID iD iconorcid.org/0000-0002-3525-8349
Alternative names
Publications (10 of 133) Show all publications
Boucenna, S. M., Ohlsson, T. & Pernow, M. (2019). A minimal non-supersymmetric SO(10) model with Peccei-Quinn symmetry. Physics Letters B, 792, 251-257
Open this publication in new window or tab >>A minimal non-supersymmetric SO(10) model with Peccei-Quinn symmetry
2019 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 792, p. 251-257Article in journal (Refereed) Published
Abstract [en]

We present a minimal non-supersymmetric SO(10) GUT breaking directly to the Standard Model gauge group. Precise gauge coupling unification is achieved due to the presence of two color-octet scalars, one of which is accessible to LHC searches. Proton lifetime is predicted to be below 4.5 x 10(34) years, which is within the projected five-year sensitivity of the proposed Hyper-Kamiokande experiment. We find that the Standard Model observables are reproduced to a reasonable accuracy in a numerical fit, which also predicts the unknown neutrino parameters. Finally, the two scalar representations stabilize the electroweak vacuum and the dark matter is comprised of axions.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-251700 (URN)10.1016/j.physletb.2019.03.045 (DOI)000466802100038 ()2-s2.0-85063758281 (Scopus ID)
Note

Correction in DOI:10.1016/j.physletb.2019.134902

QC 20190520

Available from: 2019-05-20 Created: 2019-05-20 Last updated: 2019-10-28Bibliographically approved
Kühnel, F. & Ohlsson, T. (2019). Decaying dark matter in halos of primordial black holes. European Physical Journal C, 79(8), Article ID 687.
Open this publication in new window or tab >>Decaying dark matter in halos of primordial black holes
2019 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 79, no 8, article id 687Article in journal (Refereed) Published
Abstract [en]

We investigate photon signatures of general decaying dark-matter particles in halos of primordial black holes. We derive the halo-profile density and the total decay rate for these combined dark-matter scenarios. For the case of axion-like particles of masses below O(1)keV, we find strong bounds on the decay constant which are several orders of magnitude stronger than the strongest existing bounds, for all halo masses above O(10-5) solar masses. Using future X-ray measurements, it will be possible to push these bounds on such combined dark-matter scenarios even further.

Place, publisher, year, edition, pages
Springer, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-257436 (URN)10.1140/epjc/s10052-019-7173-x (DOI)000480817200003 ()2-s2.0-85070680713 (Scopus ID)
Note

QC 20190830

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-09-05Bibliographically approved
Ohlsson, T. & Pernow, M. (2019). Fits to non-supersymmetric SO(10) models with type I and II seesaw mechanisms using renormalization group evolution. Journal of High Energy Physics (JHEP) (6), Article ID 085.
Open this publication in new window or tab >>Fits to non-supersymmetric SO(10) models with type I and II seesaw mechanisms using renormalization group evolution
2019 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 6, article id 085Article in journal (Refereed) Published
Abstract [en]

We consider numerical fits to non-supersymmetric SO(10)-based models in which neutrino mass is generated by the type-I or type-II seesaw mechanism or a combination of both. The fits are performed with a sophisticated top-down procedure, taking into account the renormalization group equations of the gauge and Yukawa couplings, integrating out relevant degrees of freedom at their corresponding mass scales, and using recent data for the Standard Model observables. We find acceptable fits for normal neutrino mass ordering only and with neutrino mass generated by either type-I seesaw only or a combination of types I and II seesaw in which type-I seesaw is dominant. Furthermore, we find predictions from the best fit regarding the small neutrino masses, the effective neutrinoless double beta decay mass, and the leptonic CP-violating phase. Finally, we show that the fits are rather insensitive to the chosen value of the unification scale.

Place, publisher, year, edition, pages
SPRINGER, 2019
Keywords
Beyond Standard Model, GUT, Neutrino Physics
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-255188 (URN)10.1007/JHEP06(2019)085 (DOI)000472210600002 ()2-s2.0-85067629668 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-18Bibliographically approved
Boucenna, S. M., Kühnel, F., Ohlsson, T. & Visinelli, L. (2018). Novel constraints on mixed dark-matter scenarios of primordial black holes and WIMPs. Journal of Cosmology and Astroparticle Physics (7), Article ID 003.
Open this publication in new window or tab >>Novel constraints on mixed dark-matter scenarios of primordial black holes and WIMPs
2018 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 7, article id 003Article in journal (Refereed) Published
Abstract [en]

We derive constraints on mixed dark-matter scenarios consisting of primordial black holes (PBHs) and weakly interacting massive particles (WIMPs). In these scenarios, we expect a density spike of the WIMPs that are gravitationally bound to the PBHs, which results in an enhanced annihilation rate and increased indirect detection prospects. We show that such scenarios provide strong constraints on the allowed fraction of PBHs that constitutes the dark matter, depending on the WIMP mass m(x) and the velocity-averaged annihilation cross-section <sigma v >. For the standard scenario with m(x) = 100 GeV and <sigma v > = 3 x 10(-26) cm(3)/s, we derive bounds that are stronger than all existing bounds for PBHs with masses 10(-12) M-circle dot less than or similar to M-BH less than or similar to 10(4) where M-circle dot, is the solar mass, and mostly so by several orders of magnitude.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
dark matter theory, primordial black holes
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-232405 (URN)10.1088/1475-7516/2018/07/003 (DOI)000437299100003 ()2-s2.0-85051711141 (Scopus ID)
Note

QC 20180726

Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-10-16Bibliographically approved
Huang, G.-y., Ohlsson, T. & Zhou, S. (2018). Observational constraints on secret neutrino interactions from big bang nucleosynthesis. Physical Review D: covering particles, fields, gravitation, and cosmology, 97(7), Article ID 075009.
Open this publication in new window or tab >>Observational constraints on secret neutrino interactions from big bang nucleosynthesis
2018 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 97, no 7, article id 075009Article in journal (Refereed) Published
Abstract [en]

We investigate possible interactions between neutrinos and massive scalar bosons via g(phi)(nu) over bar nu phi (or massive vector bosons via g(V)(nu) over bar gamma(mu)nu V-mu) and explore the allowed parameter space of the coupling constant g phi (or g(V)) and the scalar (or vector) boson mass m(phi) (or m(V)) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of big bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on g(phi) and m(phi) in the scalar-boson case is rather weak, due to a small number of degrees of freedom (d.o.f.). However, in the vector-boson case, the most stringent bound on the coupling g(V) less than or similar to 6 x 10(-10) at 95% confidence level is obtained for m(V) similar or equal to 1 MeV, while the bound becomes much weaker g(V) less than or similar to 8 x 10(-6) for smaller masses m(V) less than or similar to 10(-4) MeV. Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.

Place, publisher, year, edition, pages
American Physical Society, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-228129 (URN)10.1103/PhysRevD.97.075009 (DOI)000429221900001 ()2-s2.0-85046723245 (Scopus ID)
Note

QC 20180518

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-10-31Bibliographically approved
Ohlsson, T. & Pernow, M. (2018). Running of fermion observables in non-supersymmetric SO(10) models. Journal of High Energy Physics (JHEP) (11), Article ID 028.
Open this publication in new window or tab >>Running of fermion observables in non-supersymmetric SO(10) models
2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 11, article id 028Article in journal (Refereed) Published
Abstract [en]

We investigate the complete renormalization group running of fermion observables in two different realistic non-supersymmetric models based on the gauge group SO(10) with intermediate symmetry breaking for both normal and inverted neutrino mass orderings. Contrary to results of previous works, we find that the model with the more minimal Yukawa sector of the Lagrangian fails to reproduce the measured values of observables at the electroweak scale, whereas the model with the more extended Yukawa sector can do so if the neutrino masses have normal ordering. The difficulty in finding acceptable fits to measured data is a result of the added complexity from the effect of an intermediate symmetry breaking as well as tension in the value of the leptonic mixing angle theta 23

Place, publisher, year, edition, pages
SPRINGER, 2018
Keywords
Beyond Standard Model, GUT
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-239786 (URN)10.1007/JHEP11(2018)028 (DOI)000449809000004 ()2-s2.0-85056110172 (Scopus ID)
Note

QC 20190108

Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-09-18Bibliographically approved
Herrero-Garcia, J., Ohlsson, T., Riad, S. & Wirén, J. (2017). Full parameter scan of the Zee model: exploring Higgs lepton flavor violation. Journal of High Energy Physics (JHEP) (4), Article ID 130.
Open this publication in new window or tab >>Full parameter scan of the Zee model: exploring Higgs lepton flavor violation
2017 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 4, article id 130Article in journal (Refereed) Published
Abstract [en]

We study the general Zee model, which includes an extra Higgs scalar doublet and a new singly-charged scalar singlet. Neutrino masses are generated at one-loop level, and in order to describe leptonic mixing, both the Standard Model and the extra Higgs scalar doublets need to couple to leptons (in a type-III two-Higgs doublet model), which necessarily generates large lepton flavor violating signals, also in Higgs decays. Imposing all relevant phenomenological constraints and performing a full numerical scan of the parameter space, we find that both normal and inverted neutrino mass orderings can be fitted, although the latter is disfavored with respect to the former. In fact, inverted ordering can only be accommodated if theta(23) turns out to be in the first octant. A branching ratio for h -> tau mu of up to 10(-2) is allowed, but it could be as low as 10(-6). In addition, if future expected sensitivities of tau -> mu gamma are achieved, normal ordering can be almost completely tested. Also, mu e conversion is expected to probe large parts of the parameter space, excluding completely inverted ordering if no signal is observed. Furthermore, non-standard neutrino interactions are found to be smaller than 10(-6), which is well below future experimental sensitivity. Finally, the results of our scan indicate that the masses of the additional scalars have to be below 2.5 TeV, and typically they are lower than that and therefore within the reach of the LHC and future colliders.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Neutrino Physics, Beyond Standard Model, Higgs Physics
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-207676 (URN)10.1007/JHEP04(2017)130 (DOI)000400007000001 ()2-s2.0-85018567259 (Scopus ID)
Note

QC 20170601

Available from: 2017-06-01 Created: 2017-06-01 Last updated: 2017-11-10Bibliographically approved
Meloni, D., Ohlsson, T. & Riad, S. (2017). Renormalization group running of fermion observables in an extended non-supersymmetric SO(10) model. Journal of High Energy Physics (JHEP) (3), Article ID 045.
Open this publication in new window or tab >>Renormalization group running of fermion observables in an extended non-supersymmetric SO(10) model
2017 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 3, article id 045Article in journal (Refereed) Published
Abstract [en]

We investigate the renormalization group evolution of fermion masses, mixings and quartic scalar Higgs self-couplings in an extended non-supersymmetric SO(10) model, where the Higgs sector contains the 10(H), 120(H), and 126(H) representations. The group SO(10) is spontaneously broken at the GUT scale to the Pati-Salam group and subsequently to the Standard Model (SM) at an intermediate scale MI. We explicitly take into account the effects of the change of gauge groups in the evolution. In particular, we derive the renormalization group equations for the different Yukawa couplings. We find that the computed physical fermion observables can be successfully matched to the experimental measured values at the electroweak scale. Using the same Yukawa couplings at the GUT scale, the measured values of the fermion observables cannot be reproduced with a SM-like evolution, leading to differences in the numerical values up to around 80%. Furthermore, a similar evolution can be performed for a minimal SO(10) model, where the Higgs sector consists of the 10(H) and 126(H) representations only, showing an equally good potential to describe the low-energy fermion observables. Finally, for both the extended and the minimal SO(10) models, we present predictions for the three Dirac and Majorana CP-violating phases as well as three effective neutrino mass parameters.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Beyond Standard Model, GUT, Neutrino Physics
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-205465 (URN)10.1007/JHEP03(2017)045 (DOI)000397672700005 ()2-s2.0-85014946783 (Scopus ID)
Note

QC 20170522

Available from: 2017-05-22 Created: 2017-05-22 Last updated: 2017-11-13Bibliographically approved
Kuhnel, F. & Ohlsson, T. (2017). Signatures of compact halos of sterile-neutrino dark matter. Physical Review D: covering particles, fields, gravitation, and cosmology, 96(10), Article ID 103020.
Open this publication in new window or tab >>Signatures of compact halos of sterile-neutrino dark matter
2017 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 96, no 10, article id 103020Article in journal (Refereed) Published
Abstract [en]

We investigate compact halos of sterile-neutrino dark matter and examine observable signatures with respect to neutrino and photon emission. Primarily, we consider two cases: primordial black-hole halos and ultracompact minihalos. In both cases, we find that there exists a broad range of possible parameter choices such that detection in the near future with x-ray and gamma-ray telescopes might be well possible. In fact, for energies above 10 TeV, the neutrino telescope IceCube would be a splendid detection machine for such macroscopic dark-matter candidates.

Place, publisher, year, edition, pages
American Physical Society, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-220271 (URN)10.1103/PhysRevD.96.103020 (DOI)000416315600003 ()2-s2.0-85037061947 (Scopus ID)
Funder
Swedish Research Council, 638-2013-8993
Note

QC 20180110

Available from: 2018-01-10 Created: 2018-01-10 Last updated: 2018-01-10Bibliographically approved
Ohlsson, T. (2016). Non-Hermitian neutrino oscillations in matter with PT symmetric Hamiltonians. Europhysics letters, 113(6), Article ID 61001.
Open this publication in new window or tab >>Non-Hermitian neutrino oscillations in matter with PT symmetric Hamiltonians
2016 (English)In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 113, no 6, article id 61001Article in journal (Refereed) Published
Abstract [en]

We introduce and develop a novel approach to extend the ordinary two-flavor neutrino oscillation formalism in matter using a non-Hermitian PT symmetric effective Hamiltonian. The condition of PT symmetry is weaker and less mathematical than that of hermicity, but more physical, and such an extension of the formalism can give rise to sub-leading effects in neutrino flavor transitions similar to the effects by so-called non-standard neutrino interactions. We derive the necessary conditions for the spectrum of the effective Hamiltonian to be real as well as the mappings between the fundamental and effective parameters. We find that the real spectrum of the effective Hamiltonian will depend on all new fundamental parameters introduced in the non-Hermitian PT symmetric extension of the usual neutrino oscillation formalism and that either i) the spectrum is exact and the effective leptonic mixing must always be maximal or ii) the spectrum is approximate and all new fundamental parameters must be small.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-187277 (URN)10.1209/0295-5075/113/61001 (DOI)000374764700010 ()2-s2.0-84963847170 (Scopus ID)
Note

QC 20160519

Available from: 2016-05-19 Created: 2016-05-19 Last updated: 2019-10-02Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3525-8349

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