186 research outputs found

### Predictions from a flavour GUT model combined with a SUSY breaking sector

We discuss how flavour GUT models in the context of supergravity can be
completed with a simple SUSY breaking sector, such that the flavour-dependent
(non-universal) soft breaking terms can be calculated. As an example, we
discuss a model based on an SU(5) GUT symmetry and $A_4$ family symmetry, plus
additional discrete "shaping symmetries" and a $\mathbb{Z}_4^\mathrm{R}$
symmetry. We calculate the soft terms and identify the relevant high scale
input parameters, and investigate the resulting predictions for the low scale
observables, such as flavour violating processes, the sparticle spectrum and
the dark matter relic density.Comment: 24 pages, 3 figure

### Flavour model building in the framework of Grand Unification and supergravity

In this thesis, we study new aspects of flavour model building in the context of supersymmetric Grand Unified Theories, where the focus lies on models with an SU(5) or SO(10) gauge group.
In the framework of supergravity, we discuss how a typical flavon sector of a flavour model with spontaneously broken family symmetry can be combined with a SUSY breaking sector in a consistent manner. To demonstrate the predictive power of such an implementation, an example calculation for a flavour GUT model, which is based on an SU(5) gauge group, an A_4 family symmetry and a Z^R_4 R-symmetry, is performed. Assuming hidden sector SUSY breaking, we determine the structure of the soft SUSY breaking terms at the GUT scale and investigate the predictions for observables at low energy scales, such as the sparticle spectrum, the dark matter relic density and flavour violating processes.
Next, we carry out a systematic analysis of a class of predictive SU(5) flavour GUT models with the CSD2 setup in the neutrino sector, and where the ratios of the Yukawa couplings in the down-quark and charged lepton sector are fixed by Clebsch-Gordan coefficients at the GUT scale, following the principle of single operator dominance. Alongside the identification of viable model candidates by performing a fit to experimental data for different combinations of CG coefficients, we calculate, among others, the predictions for the 2-3 mixing angle theta^PMNS_23 and the CP violating phase delta^PMNS in the lepton sector.
In the context of SO(10) Grand Unification, a class of non-renormalizable Yukawa operators of the schematic form 16_I 16_J H 45^n 210^m is investigated, where H in {10,120,126bar} contains SU(2)_L doublet and antidoublet states, and 16_I,J the SM fermions. Moreover, the representations 45 and 210 acquire SM singlet vevs at the GUT scale. We provide general formulas to compute the resulting Yukawa couplings in the different fermion sectors of the MSSM, and discuss the construction of such operators from renormalizable interactions by using heavy mediators. In addition, we show that the alignment of the MSSM Higgs (anti)doublets H_u and H_d in the space of all SU(2)_L (anti)doublets of a concrete model is a central aspect for the prediction of Yukawa ratios at the GUT scale.
Finally, we specify the numerical procedure to quantitatively calculate nucleon decay from dimension 5 operators in SUSY models, and apply the analysis to an example model with an SU(5) GUT symmetry

### Non-universal Z' from SO(10) GUTs with vector-like family and the origin of neutrino masses

A $Z'$ gauge boson with mass around the (few) TeV scale is a popular example
of physics beyond the Standard Model (SM) and can be a fascinating remnant of a
Grand Unified Theory (GUT). Recently, $Z'$ models with non-universal couplings
to the SM fermions due to extra vector-like states have received attention as
potential explanations of the present $R_K$, $R_{K^{\ast}}$ anomalies; this
includes GUT model proposals based on the $\mathrm{SO}(10)$ group. In this
paper we further develop GUT models with a flavour non-universal low scale $Z'$
and clarify several outstanding issues within them. First, we successfully
incorporate a realistic neutrino sector (with linear and/or inverse low scale
seesaw mechanism), which was so far a missing ingredient. Second, we
investigate in detail their compatibility with the $R_K$, $R_{K^{\ast}}$
anomalies; we find that the anomalies do not have a consistent explanation
within such models. Third, we demonstrate that these models have other
compelling phenomenological features; we study the correlations between the
flavour violating processes of $\mu\to 3e$ and $\mu$-$e$ conversion in a muonic
atom, showing how a GUT imprint could manifest itself in experiments.Comment: Revised version, published in NPB. New material, general conclusions
unchanged. 30 pages, 4 figures, 2 table

### Comparatively Light Extra Higgs States as Signature of SUSY $\mathrm{SO}(10)$ GUTs with 3rd Family Yukawa Unification

We study $3$rd family Yukawa unification in the context of supersymmetric
(SUSY) $\mathrm{SO}(10)$ GUTs and $\mathrm{SO}(10)$-motivated boundary
conditions for the SUSY-breaking soft terms. We consider $\mu<0$ such that the
SUSY loop-threshold effects enable a good fit to all third family masses of the
charged Standard Model (SM) fermions. We find that fitting the third family
masses together with the mass of the SM-like Higgs particle, the scenario
predicts the masses of the superpartner particles and of the extra Higgs states
of the MSSM: while the sparticles are predicted to be comparatively heavy
(above the present LHC bound but within reach of future colliders), the
spectrum has the characteristic feature that the lightest new particles are the
extra MSSM Higgses. We show that this effect is rather robust with respect to
many deformations of the GUT boundary conditions, but turns out to be sensitive
to the exactness of top-bottom Yukawa unification. Nevertheless, with moderate
deviations of a few percent from exact top-bottom Yukawa unification (stemming
e.g.\ from GUT-threshold corrections or higher-dimensional operators), the
scenario still predicts extra MSSM Higgs particles with masses not much above
$1.5\,\mathrm{TeV}$, which could be tested e.g.\ by future LHC searches for
ditau decays $H^0/A^{0}\to\tau\tau$. Finding the extra MSSM Higges before the
other new MSSM particles could thus be a smoking gun for a Yukawa unified
$\mathrm{SO}(10)$ GUT.Comment: 39 pages, 13 figures, 1 table, 2 appendice

### Employing nucleon decay as a fingerprint of SUSY GUT models using SusyTCProton

While the observation of nucleon decay would be a smoking gun of Grand Unified Theories (GUTs) in general, the ratios between the decay rates of the various channels carry rich information about the specific GUT model realization. To investigate this fingerprint of GUT models in the context of supersymmetric (SUSY) GUTs, we present the software tool SusyTCProton, which is an extension of the module SusyTC to be used with the REAP package. It allows to calculate nucleon decay rates from the relevant dimension five GUT operators specified at the GUT scale, including the full loop-dressing at the SUSY scale. As an application, we investigate the fingerprints of two example GUT toy models with different flavor structures, performing an MCMC analysis to include the experimental uncertainties for the charged fermion masses and CKM mixing parameters. While both toy models provide equally good fits to the low energy data, we show how they could be distinguished via their predictions of ratios for nucleon decay rates. Together with SusyTCProton we also make the additional module ProtonDecay public. It can be used independently from REAP and allows to calculate nucleon decay rates from given D = 5 and D = 6 operator coefficients (accepting the required SUSY input for the D = 5 case in SLHA format). The D = 6 functionality can also be used to calculate nucleon decay in non-SUSY GUTs

### Predicting $\delta^\text{PMNS}$, $\theta_{23}^\text{PMNS}$ and fermion mass ratios from flavour GUTs with CSD2

Constrained Sequential neutrino Dominance of type 2 (referred to as CSD2) is
an attractive building block for flavour Grand Unified Theories (GUTs) because
it predicts a non-zero leptonic mixing angle $\theta_{13}^\text{PMNS}$, a
deviation of $\theta_{23}^\text{PMNS}$ from $\pi /4$, as well as a leptonic
Dirac CP phase $\delta^\text{PMNS}$ which is directly linked to the CP
violation relevant for generating the baryon asymmetry via the leptogenesis
mechanism. When embedded into GUT flavour models, these predictions are
modified in a specific way, depending on which GUT operators are responsible
for generating the entries of fermion Yukawa matrices. In this paper, we
systematically investigate and classify the resulting predictions from
supersymmetric $\mathrm{SU}(5)$ based flavour models by fitting the known
fermion mass and mixing data, in order to provide a roadmap for future model
building. Interestingly, the promising models predict the lepton Dirac CP phase
$\delta^\mathrm{PMNS}$ between $230^\circ$ and $290^\circ$, and the quark CP
phase $\delta^\mathrm{CKM}$ in accordance with a right-angled unitarity
triangle ($\alpha_\mathrm{UT}=90^\circ$). Also, our model setup predicts the
quantities $\theta_{23}^\mathrm{PMNS}$ and $m_d/m_s$ with less uncertainty than
current experimental precision, and allowing with future sensitivity to
discriminate between them.Comment: 46 pages, 6 figures, 3 tables; we provide neutrino RGE data tables at
https://particlesandcosmology.unibas.ch/fileadmin/user_upload/particlesandcosmology-unibas-ch/files/RGrunning.zi

### COVID-19 Testing Unit Munich: Impact of Public Health and Safety Measures on Patient Characteristics and Test Results, January to September 2020

To assess the course of the COVID-19 pandemic and the impact of non-pharmaceutical interventions, the number of reported positive test results is frequently used as an estimate of the true number of population-wide infections. We conducted a retrospective observational analysis of patient data of the Corona Testing Unit (CTU) in Munich, Bavaria, Germany between January 27th, and September 30th, 2020. We analyzed the course of daily patient numbers over time by fitting a negative binomial model with multiple breakpoints. Additionally, we investigated possible influencing factors on patient numbers and characteristics by literature review of policy papers and key informant interviews with individuals involved in the set-up of the CTU. The 3,963 patients included were mostly young (median age: 34, interquartile range: 27–48), female (66.2%), and working in the healthcare sector (77%). For these, 5,314 real-time RT-PCR tests were conducted with 157 (2.94%) positive results. The overall curve of daily tests and positive results fits the re-ported state-wide incidence in large parts but shows multiple breakpoints with considerable trend changes. These can be most fittingly attributed to testing capacities and -strategies and individual risk behavior, rather than public health measures. With the large impact on patient numbers and pre-test probabilities of various strategic and operational factors, we consider the derived re-ported incidence as a poor measurement to base policy decisions on. Testing units should be prepared to encounter these fluctuations with a quickly adaptable structure

### Modelling of a triage scoring tool for SARS-COV-2 PCR testing in health-care workers: data from the first German COVID-19 Testing Unit in Munich

Background
Numerous scoring tools have been developed for assessing the probability of SARS-COV-2 test positivity, though few being suitable or adapted for outpatient triage of health care workers.
Methods
We retrospectively analysed 3069 patient records of health care workers admitted to the COVID-19 Testing Unit of the Ludwig-Maximilians-Universität of Munich between January 27 and September 30, 2020, for real-time polymerase chain reaction analysis of naso- or oropharyngeal swabs. Variables for a multivariable logistic regression model were collected from self-completed case report forms and selected through stepwise backward selection. Internal validation was conducted by bootstrapping. We then created a weighted point-scoring system from logistic regression coefficients.
Results
4076 (97.12%) negative and 121 (2.88%) positive test results were analysed. The majority were young (mean age: 38.0), female (69.8%) and asymptomatic (67.8%). Characteristics that correlated with PCR-positivity included close-contact professions (physicians, nurses, physiotherapists), flu-like symptoms (e.g., fever, rhinorrhoea, headache), abdominal symptoms (nausea/emesis, abdominal pain, diarrhoea), less days since symptom onset, and contact to a SARS-COV-2 positive index-case. Variables selected for the final model included symptoms (fever, cough, abdominal pain, anosmia/ageusia) and exposures (to SARS-COV-positive individuals and, specifically, to positive patients). Internal validation by bootstrapping yielded a corrected Area Under the Receiver Operating Characteristics Curve of 76.43%. We present sensitivity and specificity at different prediction cut-off points. In a subgroup with further workup, asthma seems to have a protective effect with regard to testing result positivity and measured temperature was found to be less predictive than anamnestic fever.
Conclusions
We consider low threshold testing for health care workers a valuable strategy for infection control and are able to provide an easily applicable triage score for the assessment of the probability of infection in health care workers in case of resource scarcity

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