Department of Physics
http://hdl.handle.net/11073/16587
Sat, 15 May 2021 17:15:22 GMT2021-05-15T17:15:22ZCorrections to Yukawa couplings from higher dimensional operators in a natural SUSY SO(10) and HL-LHC implications
http://hdl.handle.net/11073/21305
Corrections to Yukawa couplings from higher dimensional operators in a natural SUSY SO(10) and HL-LHC implications
Aboubrahim, Amin; Nath, Pran; Syed, Raza
We consider a class of unified models based on the gauge group SO(10) which with appropriate choice of Higgs representations generate in a natural way a pair of light Higgs doublets needed to accomplish electroweak symmetry breaking. In this class of models higher dimensional operators of the form matter-matter-Higgs-Higgs in the superpotential after spontaneous breaking of the GUT symmetry generate contributions to Yukawa couplings which are comparable to the ones from cubic interactions. Specifically we consider an SO(10) model with a sector consisting of 126 + 126 + 210 of heavy Higgs which breaks the GUT symmetry down to the standard model gauge group and a sector consisting of 2 × 10 + 120 of light Higgs fields. In this model we compute the corrections from the quartic interactions to the Yukawa couplings for the top and the bottom quarks and for the tau lepton. It is then shown that inclusion of these corrections to the GUT scale Yukawas allows for consistency of the top, bottom and tau masses with experiment for low tan β with a value as low as tan β of 5–10. We compute the sparticle spectrum for a set of benchmarks and find that satisfaction of the relic density is achieved via a compressed spectrum and coannihilation and three sets of coannihilations appear: chargino-neutralino, stop-neutralino and stau-neutralino. We investigate the chargino-neutralino coannihilation in detail for the possibility of observation of the light chargino at the high luminosity LHC (HL-LHC) and at the high energy LHC (HE-LHC) which is a possible future 27 TeV hadron collider. It is shown that all benchmark models but one can be discovered at HL-LHC and all would be discoverable at HE-LHC. The ones discoverable at both machines require a much shorter time scale and a lower integrated luminosity at HE-LHC.
Mon, 11 Jan 2021 00:00:00 GMThttp://hdl.handle.net/11073/213052021-01-11T00:00:00ZInvestigations of the Co-Pt alloy phase diagram with neutron diffuse scattering, inverse cluster variation method, and Monte Carlo simulations
http://hdl.handle.net/11073/19808
Investigations of the Co-Pt alloy phase diagram with neutron diffuse scattering, inverse cluster variation method, and Monte Carlo simulations
Fevre, Mathieu; Sanchez, Juan; Stewart,Ross; Merot, J. S.; Fossard, Frédéric; Le Bouar, Yann; Tanaka, Katsushi; Numakura, Hiroshi; Schmerber, Guy; Pierron-Bohnes, Véronique
The short-range order in a CoPt alloy was determined at 1203 and 1423 K using neutron diffuse scattering measurements. The effective pair interactions provided by data analysis reproduce well the experimental order-disorder transition temperature in Monte Carlo simulations. They complete previous results reported for the Co-Pt system and are compared to those obtained within tight-binding and ab initio formalisms. Our results show that the important dependence of the nearest-neighbor pair interactions with composition is not related to the sample magnetic state at the measured temperatures. Interactions measured in the paramagnetic domain for the CoPt alloy behave like those in the ferromagnetic domain for the Co₃Pt and Co₀․₆₅Pt₀․₃₅ alloys. The effective pair interactions related to the tight-binding Ising model provide a relatively good description of the CoPt alloy thermodynamics close to the ordering temperature (short-range order and temperature of phase transformation), even if they strongly differ from those measured in this study. The average magnetic moment of Co atoms at high temperatures was determined from the analysis of the intensity contribution that is not dependent on the scattering vector. The obtained value is very close to the moment measured at room temperature or determined from ab initio calculations. This confirms the Curie-Weiss behavior of the CoPt alloy. Finally, transmission electron microscope observations carried out on samples annealed for about 30 days confirmed that the order-disorder transition takes place in the 830–843 K temperature interval at the Co₃Pt composition.
Wed, 01 Jan 2020 00:00:00 GMThttp://hdl.handle.net/11073/198082020-01-01T00:00:00ZApplication of Quasi-Phase Matching Concept for Enhancement of High-Order Harmonics of Ultrashort Laser Pulses in Plasmas
http://hdl.handle.net/11073/16633
Application of Quasi-Phase Matching Concept for Enhancement of High-Order Harmonics of Ultrashort Laser Pulses in Plasmas
Ganeev, Rashid; Stremoukhov, Sergey; Andreev, A. V.; Alnaser, Ali
Novel methods of coherent short-wavelength sources generation require thorough analysis for their further amendments and practical implementations. In this work, we report on the quasi-phase matching (QPM) of high-order harmonics generation during the propagation of single and two-color femtosecond pulses through multi-jet plasmas, which allows the enhancement of groups of harmonics in different ranges of extreme ultraviolet. The role of the number of coherent zones; sizes of plasma jets and the distance between them; plasma formation conditions, and the characteristics of the fundamental radiation on the harmonic effciency at quasi-phase matching (QPM) conditions are analyzed. We demonstrate the ~40X enhancement factor of the maximally-enhanced harmonic with respect to the one generated at ordinary conditions in the imperforated plasma.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/11073/166332019-01-01T00:00:00ZB − L violating interactions in supersymmetric SO(10) models
http://hdl.handle.net/11073/16615
B − L violating interactions in supersymmetric SO(10) models
Nath, Pran; Syed, Raza
An analysis is given of B − L violating interactions in SO(10) arising from the integration of $10+\bar{10}$ of SU(5) of heavy Higgs. The analysis is done within the well defined missing partner model where the doublet-triplet splitting arises naturally. The Higgs representations of the model consist of two 10-plets, one 120, one 210 plet and a $126+\bar{126}$ representations of SO(10). The SO(10) symmetry is spontaneously broken by the singlet in the $126+\bar{126}$ and 210. In this work we focus on the B−L interactions arising from the elimination of $10+\bar{10}$ plets of SU(5). We compute five field and six field B−L violating operators. The analysis extends previous analyses where B−L violating interactions arising from the elimination of $5+\bar{5}$ and $45+\bar{45}$ were computed. Specifically we compute dimension 6, 7 and 9 operators. These interactions can generate GUT scale baryogengesis, proton decay, and 𝓃-\bar{𝓃} oscillations.
Tue, 01 Jan 2019 00:00:00 GMThttp://hdl.handle.net/11073/166152019-01-01T00:00:00Z