- Indico style
- Indico style - inline minutes
- Indico style - numbered
- Indico style - numbered + minutes
- Indico Weeks View
The Young Scientists Meeting is a three-day meeting for all members of the Collaborative Research Center (CRC) TRR 257. The scientific talks will be presented by young scientists (PhD students or Postdocs) and they will focus on the various projects of our CRC. This will give all participants the opportunity to gain a better overview of these projects and allow the speakers to present their research in front of a large audience. Besides scientific talks, this workshop also includes talks about soft skills and gender equality.
Due to the pandemic situation of the last years, this meeting is also a chance to reconnect to colleagues and promote mobility among the various institutes and departments of the CRC. Therefore every member of the CRC TRR 257 is invited to participate.
The workshop will be held in person at the Karlsruher Institut für Technologie (KIT) from 8th June to 10th June 2022.
Abstract submission deadline: | 1st May 2022 |
Registration deadline: | 1st May 2022 |
The Composite 2-Higgs-Doublet Model (C2HDM) is a composite Higgs Model where two Higgs doublets arise as pseudo Nambu-Goldstone bosons in order to retrieve the well known 2HDM but with couplings already predetermined by the composite nature of the model. Fermion masses are generated through partial compositeness entailing new heavy fermions. In this talk we present Higgs Pair production in this model via gluon fusion, including higher order QCD corrections. We investigate the impact of the higher-order corrections as well as the impact of the compositeness nature of the model with the new heavy fermions on the phenomenology of Higgs pair production.
The theoretical calculation is described in detail and specific benchmark scenarios are explored.
In practical applications for effective field theories, it is often necessary to obtain a complete set of independent operators, but constructing such an operator basis is remarkably challenging. In this talk, I will report on our implementation of a recently proposed group-theoretical algorithm that systematically accounts for the redundancies arising from equations of motion and integration-by-parts identities among the operators. $\texttt{AutoEFT}$ can be applied to phenomenologically relevant theories such as the Standard Model or extensions of it, including new light particles and additional symmetry groups.
In this talk I discuss peculiarities that arise in the computation of real-emission contributions to observables that contain Heaviside functions. Specifically I will discuss the calculation of the zero-jettiness soft function in SCET at next-to-next-to-next-to-leading order in perturbative QCD. The Heaviside functions prevent a direct use of multi-loop methods based on reverse unitarity. I will present a way to bypass this problem and illustrate key aspects of the calculation. Finally I will present some results for various non-trivial contributions to the zero-jettiness soft function.
We present a novel formalism to calculate jet functions automatically at next-to-next-to-leading
order in perturbation theory. By employing suitable phase-space parameterisations in combination with
sector-decomposition steps and selector functions, we managed to factorise all divergences in the
phase-space integrations, and we implemented our framework in the publicly available code pySecDec.
Our approach covers a wide class of SCET-1 and SCET-2 observables, and we present results for
several event-shape observables for both quark and gluon jet functions.
After providing a quick overview of what my daily work entails, I will offer a few remarks about my decision of leaving academia and personal experience of applying to several (German) companies. I plan to leave enough time for discussion, so bring your own questions!
Picture a Scientist is a 2020 documentary highlighting gender inequality in science
I will present our calculation of massive quark form factors at three loops in QCD.
After reducing the Feynman integrals in the amplitudes to master integrals, these were computed by solving differential equations. By constructing expansions around regular as well as singular points and numerical matching, we obtain sufficient precision over the whole kinematic range.
NRQCD is a non-relativistic effective theory used, for example, to describe QCD bound states such as the $\Upsilon$(1S) meson. The matching of the effective theory NRQCD to the full theory QCD requires the calculation of matching coefficients. One of these matching coefficients, the matching coefficient of the vector current, plays an important role in the calculation of the decay width of the $\Upsilon$(1S) meson. The talk will focus on the calculation of this coefficient including two mass scales up to NNLO. Also the calculation of the scalar, pseudoscalar and axialvector current matching coefficients are presented.
Ultra-relativistic particles can be produced by the decay of weak-scale LLPs and act as dark radiation. The cosmologically interesting range $\Delta N_\text{eff} \sim 0.01–0.1$ corresponds to LLP decay lengths at the mm scale. These decay lengths lie at the boundary between prompt and displaced signatures at the LHC. We consider a scenario where the LLP decays into a lepton and a (nearly) massless invisible particle. By reinterpreting searches for promptly decaying sleptons and for displaced leptons we can then compare LHC exclusions with cosmological observables. We find that the CMB-S4 target value is already excluded by current LHC searches.
I will discuss a flavoured dark matter (DM) model set up in the so called Dark Minimal Flavour Violation (DMFV) framework. The model extends the Standard Model by a DM flavour triplet and a scalar mediator, through which the new dark fermions couple to right-handed up-type quarks. This interaction is governed by a new coupling matrix which is assumed to constitute the only new source of flavour and CP violation. After briefly presenting the details of this simplified model and the DMFV framework in the first part, I will continue and discuss its phenomenology in the context of collider, flavour, cosmology and direct detection constraints. I will further ‚taste‘ the flavour of the DM field by discussing which DM flavour is preferred after a combined analysis of all experimental constraints mentioned above. In the last part, I will present an estimation of the direct CP asymmetry in charm decays in this model and conclude my talk by discussing if it is capable of explaining the large measured value of this asymmetry.
The LHC experiments are entering a precision era, where the sensitivity to indirect effects of new physics, i.e. discrepancies between data and SM predictions, will increase substantially. Searches for these signals are most conveniently performed within the framework of the Standard Model Effective Field Theory (SMEFT), that allows to implement a very ambitious program: a systematic search for inconsistencies with SM predictions in a large number of different processes, from which "agnostic" information about new physics can be extracted via a combined SMEFT interpretation.
The talk will give a pedagogical introduction to the SMEFT, present the current status of this effort, illustrating some recent theory developments, and briefly discuss perspectives for the future.
In this talk we estimate the potential size of the weak annihilation amplitudes in QCD factorization as allowed by experimental data by establishing a connection between the amplitudes in the QCD factorization and the so-called topological and SU(3)-invariant descriptions. Our approach is based purely on the analysis of the tensor structure of the decay amplitudes. By focusing on the decay processes to two pseudoscalar mesons B→PP, and by considering data from CP asymmetries and branching fractions, we perform a global fit to the SU(3)-irreducible quantities. Then, we translate the outcome to the QCD factorization decomposition, and find that the most constrained weak annihilation amplitudes are below 4%. But, in view of the large uncertainties in several of the experimental input parameters, values up to 30% are allowed in certain cases.
(Part of the CRC project C1b)
In this talk, I plan to discuss the current status of theory predictions for lifetimes of heavy $H = B, D$-mesons (containing a heavy quark $Q = b,c$), which can be presented schematically within the Heavy Quark Expansion (HQE) framework as:
$$
\Gamma(H) =
\Gamma_3 +
\Gamma_5 \frac{\langle {\cal O}_5 \rangle}{m_Q^2} +
\Gamma_6 \frac{\langle {\cal O}_6 \rangle}{m_Q^3} + ...
+ 16 \pi^2
\left[
\tilde{\Gamma}_6 \frac{\langle \tilde{\mathcal{O}}_6 \rangle}{m_Q^3}
+ \tilde{\Gamma}_7 \frac{\langle \tilde{\mathcal{O}}_7 \rangle}{m_Q^4} + ...
\right],
$$
where ${\cal O}_d$ denotes the effective operator of dimension $d$, with the matrix element $ \langle {\cal O}_d \rangle \equiv \langle H | {\cal O}_d | H \rangle$, and $\Gamma_d$ is the corresponding short-distance Wilson coefficient. Then I will discuss more in detail the recent first determination of Darwin operator contribution $\Gamma_6$. In addition, I will present some results on the phenomenology, and will discuss further prospects and plans on improvement of the HQE predictions for these lifetimes - both from perturvative and non-perturbative side - by the Siegen and Karlsruhe Universities.
We present the current status of work to determine non-perturbative contributions to the physics of $B$-mesons.
Using the methods of lattice QCD, QCD sum rules, and the gradient flow, we consider quantities such as decay constants, dimension-6 and -7 matrix elements for lifetimes, and dimension-7 matrix elements for mixing.
We present analytical results for higher order corrections to the decay spectrum of inclusive semileptonic heavy hadron weak decays using the heavy quark expansion (HQE). We describe the analytical computation of the spectrum of the leptonic invariant mass for $B\rightarrow X_c \ell \bar{\nu}$ up to terms of order $1/m_b^3$ within the HQE at next-to-leading order (NLO) in $\alpha_s$. The full dependence of the differential rate on the mass of the final-state quark is taken into account. We discuss the implications of our results for the precision determination of the CKM matrix element $|V_{\rm cb}|$.
We report on the calculation of the Higgs production and decay in association with top quarks in the di-leptonic channel at NLO QCD. All resonant, non-resonant Feynman diagrams and off-shell effects are included for the top quark and $W$ boson. We examine the size of these off-shell effects by a comparison to the narrow-width approximation. Higgs boson decays are included in the narrow-width approximation. Numerical results are given at the integrated and differential level for various factorisation and renormalisation scales and different PDF sets to asses the main theoretical uncertainties. The impact of bottom quarks in the initial state is investigated.
In the Standard Model, the Higgs boson is predicted to be a scalar particle. However, a possible admixture of a $\cal{CP}$-odd component has yet to be excluded experimentally.
In this talk, I will present predictions for the associated production of a top-quark pair and a stable Higgs boson $pp\to e^+\nu_e\,\mu^-\bar{\nu}_\mu\,b\bar{b}\,H$ with possible mixing between $\cal{CP}$-even and $\cal{CP}$-odd states at NLO in QCD. I will compare the behaviour of the $\cal{CP}$-even, -odd and -mixed scenarios for the integrated fiducial cross sections and several key differential distributions. In addition, I will show that both NLO corrections and off-shell effects play an important role.
The Higgs boson production channel $t\bar{t}H(H\rightarrow b\bar{b})$ is a crucial ingredient to study the top-Yukawa coupling but suffers of a huge background. The direct $ t\bar{t}b\bar{b}$ production represents one of the main backgrounds to this process and, therefore, needs to be described properly. In this talk I will present the latest theoretical results obtained in the dileptonic decay channel. These predictions are NLO accurate in QCD and include all the full off-shell effects. I will also discuss several effects that affect this process and provide a prescription to distinguish the nature of the various $b$-jets present in the final state.
I will present a sensitivity test of the muon-Higgs coupling at a high-energy muon collider. This is motivated if there exists new physics that is not aligned with the Standard Model Yukawa interactions which are responsible for the fermion mass generation. With the accidentally small value of the muon Yukawa coupling and its subtle role in the high-energy production of multiple (vector and Higgs) bosons, I will show that it is possible to measure the muon-Higgs coupling to an accuracy of ten percent for a 10 TeV muon collider and a few percent for a 30 TeV machine by utilizing the three boson production, potentially sensitive to a new physics scale about Λ 30 − 10 TeV.
We will discuss a novel framework for addressing QCD factorization in the emission of multiple soft or collinear partons. The purpose of this discussion is to allow for a more precise description of hadron collider data and to better handle theoretical uncertainties from parton showers.
We have developed a power counting algorithm in emission amplitudes with the goal of parameterizing the accuracy of different types of parton showers. An example are inaccuracies introduced by iterating single emission amplitudes vs. the use of a multi-emission kernel. Eventually, this approach should pave to way for higher orders in QCD in parton showers.
The detailed study of the Higgs boson is one of the main tasks of contemporary particle physics. Gluon fusion, the main production channel of Higgs bosons at the LHC, has been successfully tackled up to $\text{N}^3\text{LO}$ in QCD. To fully exploit this unprecedented theoretical effort, sub-leading contributions, such as electroweak corrections, must be investigated. I will present the analytic calculations of the gluon- and quark-induced Higgs plus jet amplitudes in mixed QCD-electroweak corrections mediated by light quarks up to order $v \alpha^2 \alpha_S^{3/2}$.
In this talk, I will present the analytic calculations of leading two-loop Yukawa corrections to the Higgs pair production in the high energy limit. These corrections are introduced by exchanging a virtual Higgs boson between top-quark lines. In particular, I will discuss the Mellin-Barnes and differential-equation methods for the calculations of fully massive two-loop box master integrals in the high energy expansions.
We present results for Higgs boson pair production in gluon fusion
including both, NLO (2-loop) QCD corrections with full top quark
mass dependence as well as anomalous couplings related to operators
describing effects of physics beyond the Standard Model. The latter
can be realized in non-linear (HEFT) or linear (SMEFT) Effective
Field Theory frameworks. We show results for both and discuss the
impact of different truncation options within the SMEFT description.
The scattering of massive electroweak vector bosons allows
for sensitive tests of the mechanism of the electroweak symmetry
breaking. In run 2 of the LHC several of these processes have been
observed, and measurements with higher precision and for polarised
bosons will happen in future runs. In this talk I review the
status of theoretical predictions for vector-boson scattering
processes. I discuss some details of the calculations and a selection
of results. Moreover, the origin of large electroweak and QCD
corrections is explained.