Difference between revisions of "Master student Projects"

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=== Projects for Master students in the Nikhef B-physics (LHCb) group ===
+
=== Projects for Master students in the Nikhef B-physics (LHCb) group 2020 - 2021 ===
  
−
date: May 2015
+
date: April 2020
  
 
This is an overview with all available Master student projects in the Nikhef B-physics (LHCb) group.
 
This is an overview with all available Master student projects in the Nikhef B-physics (LHCb) group.
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either the contact person for the project and/or the Nikhef B-physics group leader:
 
either the contact person for the project and/or the Nikhef B-physics group leader:
  
−
Marcel Merk [e-mail: i93_at_nikhef.nl, Tel 020-5925107, Nikhef room N2xx]
+
Marcel Merk [e-mail: i93_at_nikhef.nl, Tel 020-5925107, Nikhef room N243]
  
 
For an overview of the theses written in the Nikhef B-physics group you can look at the
 
For an overview of the theses written in the Nikhef B-physics group you can look at the
 
[https://wiki.nikhef.nl/lhcb/Thesis_page_LHCb_Nikhef Nikhef LHCb theses page]
 
[https://wiki.nikhef.nl/lhcb/Thesis_page_LHCb_Nikhef Nikhef LHCb theses page]
  
 +
(The full list of projects at Nikhef can be found [https://wiki.nikhef.nl/education/Master_Projects here].)
 +
 +
=== Master projects in the Nikhef B-physics group ===
 +
 +
<!-- ######################################################################
 +
TEMPLATE
 +
 +
{| border="1" cellpadding="2" cellspacing="0"
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|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 1) Title </font>
 +
|}
 +
 +
'''Supervisor''' : S.Taff (staff)
 +
 +
'''Research Description:'''
 +
 +
Abstract
 +
 +
''' Relevant information: '''
 +
 +
[1]  [https://arxiv.org/abs/1507.03414 arXiv:1507.03414] (thesis or paper)
 +
 +
END TEMPLATE
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##########################################################################  -->
 +
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 1) Measurement of delta md </font>
 +
|}
 +
 +
'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
 +
 +
'''Research Description:'''
 +
 +
The decay B0->D-pi+ is very abundant in LHCb, and therefore ideal to study the oscillation frequency
 +
delta md, with which B0 mesons oscillate into anti-B0 mesons, and vice versa.
 +
This process proceeds through a so-called box diagram which might hide new yet-undiscovered particles.
 +
Recently, it has been realized that value of delta md is in tension with the valu of CKM-angle gamma,
 +
triggering renewed interest in this measurement.
 +
 +
Our group at Nikhef has 10 years experience in the analysis of B->Dh decays.
 +
This analysis may lead to a publication on behalf of the LHCb collaboration.
 +
 +
''' Relevant information: '''
 +
 +
 +
[1] [https://arxiv.org/abs/1812.06963 arXiv:1812.06963] M. Blanke, A. Buras, Emerging delta md Anomaly from Tree-Level Determinations of |Vcb| and the angle gamma
 +
 +
[2] [https://arxiv.org/abs/1911.07856 arXiv:1911.07856] D. King, A. Lenz, Th. Rauh, |Vcb| and gamma from mixing
 +
 +
[3] [https://indico.nikhef.nl/event/1379/contribution/1/material/slides/0.pdf talk] N. Tuning, CKM unitarity and B mixing
 +
 +
[4]  [https://arxiv.org/abs/1210.6750 arXiv:1210.6750] LHCb coll.,
 +
Measurement of the B0--B�0 oscillation frequency delta md with the decays B0->D-pi+ and B0->J/psiK*0
 +
 +
[5] [https://arxiv.org/abs/1805.03448 arXiv:1805.03448] LHCb coll.,
 +
Measurement of CP violation in B0->D�pi� decays
 +
 +
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 2) Searching for CPT violation </font>
 +
|}
 +
 +
'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
 +
 +
'''Research Description:'''
 +
 +
CPT symmetry is closely linked to Lorentz symmetry, and any violation
 +
would revolutionize science. There are possibilities though that supergravity could
 +
cause CPT violating effects in the system of neutral mesons.
 +
The precise study of B0s oscillations in the abundant Bs->Dspi decays can
 +
give the most stringent limits on Im(z) to date.
 +
 +
Our group at Nikhef has 10 years experience in the analysis of B->Dh decays.
 +
This analysis may lead to a publication on behalf of the LHCb collaboration.
 +
 +
''' Relevant information: '''
 +
 +
[1]  [https://arxiv.org/abs/1603.04804 arXiv:1603.04804] LHCb coll.,
 +
Search for violations of Lorentz invariance and CPT symmetry in B0(s) mixing
 +
 +
[2] [https://arxiv.org/abs/1407.1269 arXiv:1407.1269] J. van Tilburg and M. van Veghel,
 +
Status and prospects for CPT and Lorentz invariance violation searches in neutral meson mixing
 +
 +
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 3) BR(B0->D-pi+) and fd/fu with B+->D0pi+ </font>
 +
|}
 +
 +
'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
 +
 +
'''Research Description:'''
 +
 +
The abundant decay B0->D-pi+ is often used as normalization channel, given its
 +
clean signal, and well-known branching fraction, as measured by the B-factories.
 +
However, this branching fraction can be determined more precisely, when comparing
 +
to the decay B+->D0pi+ , which has a twice better precision.
 +
 +
In addition, the production of B0 and B+ mesons is often assumed to be equal,
 +
based on isospin symmetry. The study of B+->D0pi+ and B0->D-pi+ allows for the
 +
first measurement of this ratio, fd/fu.
 +
 +
Our group at Nikhef has 10 years experience in the analysis of B->Dh decays.
 +
This analysis may lead to a publication on behalf of the LHCb collaboration.
 +
 +
''' Relevant information: '''
 +
 +
[1]  [https://cds.cern.ch/record/2636716/files/CERN-THESIS-2018-137.pdf CERN-THESIS-2018-137] J. Butter,
 +
Branching fraction measurement of B0->D+s pi?
 +
 +
 +
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 5) Searches for new pentaquarks </font>
 +
|}
 +
 +
'''Supervisor''' : P. Koppenburg (staff)
 +
 +
'''Research Description:'''
 +
 +
In 2015 LHCb surprisingly discovered states containing five quarks, called Pc+ pentaquarks. Such particles question our understanding of confinement, the principle that forces quarks to remain in a single hadron. Which hadrons are allowed and which are not? The pentaquarks were found in the decay of the Lambda_b baryon to a Pc+ and a kaon, and Pc+ to a J/psi and a proton. This project aims at studying other similar but yet unobserved decays which could reveal the presence of the know Pc+, or yet unknown pentaquarks. The student will optimise a selection for finding such a decay in LHCb data using machine learning techniques.
 +
 +
''' Relevant information: '''
 +
 +
[1]  [https://arxiv.org/abs/1507.03414 arXiv:1507.03414] (the pentaquark paper)
 +
 +
[2] [https://arxiv.org/abs/1406.0755 arXiv:1406.0755] (a paper by P. Koppenburg similar to what the project could lead to).
 +
 +
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 6) Measurement of the relative efficiency of muons and electrons with J/psi->ll decays </font>
 +
|}
 +
 +
''' Supervisors:''' Patrick Koppenburg
 +
 +
''' Research description: '''
 +
 +
LHCb has produced intriguing results hinting at violation of lepton universality. As extraordinary claims require extraordinary evidence we propose to perform a measurement of the relative reconstruction efficiency of electrons and muons by comparing the number of J/psi particles counted in the di-electron and di-muon final states.
  
  
  
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 7) Very rare decays of B mesons</font>
 +
|}
  
−
=== Master projects in the Nikhef B-physics group ===
+
''' Supervisors:''' Marcel Merk
 +
 
 +
''' Research description: '''
 +
Decays of B-mesons to a pair of muons or a pair of electrons are very strongly suppressed in the Standard Model. As a consequence these decays are sensitive to virtual contributions of particles beyond the Standard Model. The project includes a theoretical study on these sensitivties and/or experimental improvements to the measurement. 
 +
 
 +
 
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 8) Measurement of Central Exclusive Production Rates of Chi_c using converted photons in LHCb. </font>
 +
|}
 +
 
 +
''' Supervisor:''' Kazu Akiba
 +
 
 +
''' Research description: '''
 +
Central exclusive production (CEP) of particles at the LHC is characterised by a extremely clean signature.  Differently from the typical inelastic collisions where many particles are created resulting in a so-called Primary Vertex, CEP events have only the final state particles of interest. In this project the particle of interest is a pair of charmed quarks creating a chi_c particle. In theory this process is generated by a long range gluon exchange and can elucidate the nature of the strong force, described by the quantum chromodynamics in the the standard model. The proposed work involves  analysing a pre-existing dataset with reconstructed chi_c and simulating events at the LHCb in order to obtain the relative occurrence rate of each chi_c species (spins 0, 1, 2), a quantity that can be easily compared to theoretical predictions.
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 9) Optimization studies for Vertex detector at the High Lumi LHCb </font>
 +
|}
 +
 
 +
''' Supervisor:''' Kazu Akiba
 +
 
 +
''' Research description: '''
 +
The LHCb experiment is dedicated to measure tiny differences between matter and antimatter through the precise study of rare processes involving b or c quarks.  The LHCb detector will undergo a major modification in order to dramatically increase the luminosity and be able to  measure indirect effects of physics beyond the standard model.  In this environment, over 42 simultaneous collisions are expected to happen at a time interval of 200 ps where the two proton bunches overlap. The particles of interest have a relatively long lifetime and therefore the best way to distinguish them from the background collisions is through the precise reconstruction of displaced vertices and pointing directions.  The new detector considers using extremely recent or even future technologies to measure space (with resolutions below 10 um) and time (100 ps or better) to efficiently reconstruct the events of interest for physics.  The project involves changing completely  the LHCb Vertex Locator (VELO) design in simulation and determine what can be the best performance for the upgraded detector, considering different spatial and temporal resolutions.
 +
 
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 10) Measurement of charge multiplication in heavily irradiated sensors </font>
 +
|}
 +
 
 +
''' Supervisor:''' Kazu Akiba
 +
 
 +
''' Research description: '''
 +
During the R&D phase for the LHCb VELO Upgrade detector a few sensor prototypes were irradiated to the extreme fluence expected to be achieved during the detector lifetime. These samples were tested using high energy particles at the SPS facility at CERN with their trajectories reconstructed by the Timepix3 telescope. A preliminary analysis revealed that at the highest irradiation levels the amount of signal observed is higher than expected, and even larger than the signal obtained at lower doses.  At the Device Under Test (DUT) position inside the telescope, the spatial resolution attained by this system is below 2 um. This means that a detailed analysis can be performed in order to study where and how this signal amplification happens within  the 55x55 um^2 pixel cell.  This project involves analysing the telescope and DUT data to investigate the charge multiplication mechanism at the microscopic level.
 +
 
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 11) Searching for lepton-universality violation with ?b ? ?l+l? decays </font>
 +
|}
 +
 
 +
'''Supervisor''' : Niels Tuning (staff), Lex Greeven (PhD), Mick Mulder (postdoc@CERN)
 +
 
 +
'''Research Description:'''
 +
A current �hot topic� in the field of particle physics is the potential violation of lepton-universality. At the LHCb experiment, lepton-universality tests are performed by looking at the ratio of decays
 +
into muons and into electrons/taus. Recent measurements in meson modes show hints (2 ? 3?) of lepton non-universality. Baryonic modes, however, have been less studied and provide an independent test of lepton-universality. At Nikhef, we study the decay ?b ? ?l+l- , where l can be an electron or a muon. There are two possible project topics:
 +
 
 +
1. Identifying novel analysis techniques in the high di-lepton invariant mass region. Electrons in this region undergo more Bremsstrahlung, and therefore have a worse momentum resolution,
 +
meaning background from the resonant ? (2s) mode can leak into our signal. Since we expect most of our signal in this region, it is important to improve this, most likely using machine learning techniques.
 +
 
 +
2. Identifying, simulating, and setting up a rejection for partially reconstructed ?0b ? ?*l+l? backgrounds. By not fully reconstructing the excited ?0, we can mis-reconstruct it as a signal
 +
candidate. Machine learning techniques could be explored.
 +
 
 +
 
 +
''' Relevant information: '''
 +
 
 +
[1]  [https://arxiv.org/abs/1903.09252 arXiv:1903.09252] LHCb coll., Search for lepton-universality violation in B+?K+l+l?decays
 +
 
 +
[2]  [https://arxiv.org/abs/1705.05802 arXiv:1903.09252] LHCb coll., Test of lepton universality with B0?K*0l+l? decays
 +
 
 +
[3]  [https://arxiv.org/abs/1912.08139 arXiv:1912.08139] LHCb coll., Test of lepton universality with ?b?pKl+l? decays
 +
 
 +
[4]  [https://arxiv.org/abs/1602.01399 arXiv:1602.01399] W. Detmold and S. Meinel, ?b??l+l? form factors, differential branching fraction, and angular observables from lattice QCD with relativistic b-quarks
 +
 
 +
 
 +
 
 +
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 +
<!--
 +
=============
 +
OLD PROJECTS
 +
==============
 +
-->
 +
 
 +
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 +
<!--
 +
| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 5) A Scintillator Fibers Tracker </font>
 +
|}
 +
''' Supervisors:''' Antonio Pellegrino
 +
''' Research description: '''
 +
The LHCb collaboration is upgrading the present tracking system
 +
constructing a new tracker based on scintillating fibers combined
 +
with silicon photo-multipliers (SiPM): the SciFi Tracker!
 +
Nikhef plays a key role in the project, as we will build the
 +
SciFi fibers modules, the cold-box enclosure housing the SiPMs,
 +
and a large part of the on-detector electronics. In all these
 +
areas, interesting test hardware and software has to be realized,
 +
and several research topics for a Master project are available,
 +
taking the student in contact with state-of-the-art particle detectors,
 +
in a large team of physicists and engineers. Possible collaborations
 +
with the Nikhef R&D group can also be envisaged.
 +
-->
 +
<!-- ################################################# -->
 +
 
 +
 
 +
<!-- ################################################# -->
 +
<!--
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 7) Construction of the velo upgrade detector</font>
 +
|}
 +
''' Supervisors:''' Wouter Hulsbergen
 +
''' Research description: '''
 +
Nikhef contributes to the upgraded LHCb detector (installation 2019-2020) with the construction of vertex detector modules. In this project the student participates in the construction at Nikhef, in particular in R&D studies to determine the optimize the �gluing� process (early 2018), and the analysis of the first test data taken with built modules (spring/summer 2018).
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 8) *Probing the dark sector with Y(1S)->4mu events* </font>
 +
|}
 +
''' Supervisors:''' Wouter Hulsbergen
 +
''' Research description: '''
 +
In certain parts of their parameter space Hidden Valley theories predict upsilon decays to two new dark sector particles that subsequently decay into two muons. These particles may or may not be long-lived. In this project we search for such events in LHCb run-2 data using the Turbo stream.
 +
 
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 6) The Z forward backward asymmetry </font>
 +
|}
 +
''' Supervisors:''' Wouter Hulsbergen
 +
''' Research description: '''
 +
The forward backward asymmetry of Z->mumu decays probes the standard model weak mixing angle, providing a strong test of the standard model. A dominating systematic uncertainty in this measurement is the affect of detector misalignments. In this project Z->mumu events are used to improve the detector alignment and thereby increase the precision of the run-2 measurements.
 +
 
 +
 
 +
-->
 +
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 +
 
 +
 
 +
<!-- ################################################# -->
 +
<!--
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 4) A search for heavy neutrinos in the decay of W at LHCb  </font>
 +
|}
 +
''' Supervisors:''' Wouter Hulsbergen (staff), Elena Dall'Occo (PhD)
 +
''' Research description: '''
 +
 
 +
Neutrinos are arguably the most mysterious of all known fundamental fermions as they are both much lighter than all others and only weakly interacting.
 +
It is thought that the tiny mass of neutrinos can be explained by their mixing with so-far unknown, much heavier, neutrino-like particles.
 +
In this research proposal we look for these new neutrinos in the decay of the SM W-boson using data with the LHCb experiment at CERN.
 +
The W boson is assumed to decay to a heavy neutrino and a muon. The heavy neutrino subsequently decays to a muon and a pair of quarks.
 +
Both like-sign and opposite-sign muon pairs will be studied. The result of the analysis will either be a limit on the production of the new neutrinos
 +
or the discovery of something entirely new.
 +
-->
 +
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 +
 
 +
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 +
<!-- Commented out by Niels Apr 2020.
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-
 +
! style="background:#3399ff;" | <font color=#ffffff> 2) Measurement of BR(B0 -> Ds+ Ds-) </font>
 +
|}
 +
''' Supervisors:''' Sevda Esen (postdoc), Niels Tuning (staf), Michele Veronesi (PhD)
 +
''' Research description: '''
 +
 
 +
This project aims to discover the branching fraction of the decay B0->Ds- Ds+.
 +
The decay B0->Ds- Ds+ is quite rare, because it occurs through the exchange of a W-boson between the
 +
b and the d-quark of the B0-meson.
 +
This decay proceeds via Cabibbo-suppressed W-exchange and
 +
has not yet been observed; theoretical calculations predict
 +
a branching fraction at the order of 10^-5 with a best
 +
experimental upper limit of 3.6x10^-5.
 +
 
 +
A measurement of the decay rate of B0 ->  Ds+Ds- relative to
 +
that of B0 -> D+D- can provide an estimate of the W-exchange contribution
 +
to the latter decay, a crucial piece of information for extracting
 +
the CKM angle gamma from B0 -> D(*)D(*).
 +
 
 +
The aim is to determine the relative branching fraction of  B0->Ds+Ds- with respect to B0->Ds+D- decays
 +
(which has the best known branching ratio at present, (7.2 +- 0.8)x10^-3),
 +
in close collaboration with the PhD.
 +
The aim is that this project results in a journal publication on behalf of the LHCb collaboration.
 +
For this project computer skills are needed.
 +
The ROOT programme and C++ and/or Python macros are used.
 +
This is a project that is closely related to previous analyses in the group.
 +
Weekly video meetings with CERN coordinate the efforts with in the LHCb collaboration.
 +
 
 +
''' Relevant information: '''
 +
 
 +
[1] M.Jung and S.Schacht,
 +
"Standard Model Predictions and New Physics Sensitivity in B -> DD Decays"
 +
https://arxiv.org/pdf/1410.8396.pdf
 +
[2] L.Bel, K.de Bruyn, R. Fleischer, M.Mulder, N.Tuning,
 +
"Anatomy of B -> DD Decays"
 +
https://arxiv.org/pdf/1505.01361.pdf
 +
[3] A.Zupanc et al [Belle Collaboration]
 +
"Improved measurement of B0 -> DsD+ and search for B0 -> Ds+Ds at Belle"
 +
https://arxiv.org/pdf/hep-ex/0703040.pdf
 +
[4] B.Aubert et al. [Babar Collaboration]
 +
"Search for the W-exchange decays B0 -> DD+"
 +
https://arxiv.org/pdf/hep-ex/0510051.pdf
 +
[5] R.Aaij et al. [LHCb Collaboration],
 +
"First observations of B0s -> D+D, Ds+D and D0D0 decays"
 +
https://arxiv.org/pdf/1302.5854.pdf
 +
 
 +
 
 +
{| border="1" cellpadding="2" cellspacing="0"
 +
|-  
 +
! style="background:#3399ff;" | <font color=#ffffff> 3) Measurement of relative ratio of B+ -> D0D+ and B+ -> D0Ds decays </font>
 +
|}
 +
''' Supervisors:''' Sevda Esen (postdoc), Niels Tuning (staf), Michele Veronesi (PhD)
 +
''' Research description: '''
 +
 
 +
This decay is closely related to B0->Ds- Ds+ (see above), and close collaboration between the two master projects is foreseen.
 +
The decay mode B+->D0D+ is expected to be dominated by tree diagrams with some additional
 +
contributions from penguin diagrams. Assuming SU(3) symmetry,
 +
measurement of its branching fraction relative to Cabibbo-favored
 +
B+->D0D will enable better understanding of penguin contributions
 +
to the CP violating mixing phase.
 +
 
 +
''' Relevant information: '''
 +
 
 +
[1] L.Bel, K.de Bruyn, R. Fleischer, M.Mulder, N.Tuning,
 +
"Anatomy of B -> DD Decays"
 +
https://arxiv.org/pdf/1505.01361.pdf
 +
[2] R.Aaij et al. [LHCb Collaboration],
 +
"First observations of B0s -> D+D, Ds+D and D0D0 decays"
 +
https://arxiv.org/pdf/1302.5854.pdf
 +
[3] PDG: http://pdglive.lbl.gov/BranchingRatio.action?desig=261&parCode=S041
 +
 
 +
-->
 +
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 +
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<!-- Commented out Nov 2014 by Niels (Elise is on this project)
 
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! style="background:#3399ff;" | <font color=#ffffff> 1) Study of long-living particles </font>
 
! style="background:#3399ff;" | <font color=#ffffff> 1) Study of long-living particles </font>
 
|}
 
|}
−
 
  
 
''' Supervisors:''' Wouter Hulsbergen (staf) and Veerle Heijne (PhD)
 
''' Supervisors:''' Wouter Hulsbergen (staf) and Veerle Heijne (PhD)
−
 
−
 
 
''' Research description: '''
 
''' Research description: '''
  
Line 44: Line 417:
 
The ROOT programme and C++ and/or Python macros are used. You become part of our research group
 
The ROOT programme and C++ and/or Python macros are used. You become part of our research group
 
(~5 persons); we have weekly video meetings with colleagues at CERN.  
 
(~5 persons); we have weekly video meetings with colleagues at CERN.  
−
 
  
 
''' Relevant information: '''
 
''' Relevant information: '''
−
 
 
Master thesis Suzanne Klaver (2013):  
 
Master thesis Suzanne Klaver (2013):  
 
[http://www.nikhef.nl/pub/experiments/bfys/lhcb/Theses/master/2013_SuzanneKlaver.pdf A Search for Long-lived Neutralinos in LHCb]
 
[http://www.nikhef.nl/pub/experiments/bfys/lhcb/Theses/master/2013_SuzanneKlaver.pdf A Search for Long-lived Neutralinos in LHCb]
  
 
End comment Niels Nov 2014 -->
 
End comment Niels Nov 2014 -->
 +
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 +
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<!-- Commented out July 2014 Niels
 
<!-- Commented out July 2014 Niels
  
−
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+
{| border="1" cellpadding="2" cellspacing="0" |- ! style="background:#3399ff;" | <font color=#ffffff>  
−
|-
+
2) World's best measurement of the Bc+ mass with Bc+ -> Bs pi+  
−
! style="background:#3399ff;" | <font color=#ffffff> 2) World's best measurement of the Bc+ mass with Bc+ -> Bs pi+ </font>
+
</font>|}
−
|}
+
''' Supervisors:''' Niels Tuning (staf), Jacco de Vries (PhD)
−
 
−
''' Supervisors:''' Niels Tuning (staf), Jacco de Vries (PhD)
 
−
 
−
 
 
''' Research description: '''
 
''' Research description: '''
  
Line 84: Line 453:
 
''' Relevant information: '''
 
''' Relevant information: '''
 
 
−
Master thesis Jacco de Vries (2013):
+
[1] Master thesis Jacco de Vries (2013):
 
[http://www.nikhef.nl/pub/experiments/bfys/lhcb/Theses/maste/2013_JaccoDeVries.pdf First observation of the decay Bc+ -> B0s pi+]
 
[http://www.nikhef.nl/pub/experiments/bfys/lhcb/Theses/maste/2013_JaccoDeVries.pdf First observation of the decay Bc+ -> B0s pi+]
 
 
−
LHCb collaboration, arXiv:1308.4544 (2013): [http://arxiv.org/abs/1308.4544 Observation of the decay Bc+ -> Bs pi+]
+
[2] LHCb collaboration, arXiv:1308.4544 (2013): [http://arxiv.org/abs/1308.4544 Observation of the decay Bc+ -> Bs pi+]
  
−
R. Fleischer, N. Serra and N. Tuning, Phys. Rev. D 83, 014017 (2011)
+
[3] R. Fleischer, N. Serra and N. Tuning, Phys. Rev. D 83, 014017 (2011)
 
[http://arxiv.org/abs/arXiv:1012.2784 Tests of Factorization and SU(3) Relations in B Decays into Heavy-Light Final States]
 
[http://arxiv.org/abs/arXiv:1012.2784 Tests of Factorization and SU(3) Relations in B Decays into Heavy-Light Final States]
  
 
End comment Niels Jul 2014-->
 
End comment Niels Jul 2014-->
 +
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−
 
+
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<!-- Commented out 2014 Marcel
 
<!-- Commented out 2014 Marcel
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
Line 100: Line 470:
 
! style="background:#3399ff;" | <font color=#ffffff> 2) Light Higgs search A0 -> mu+mu- </font>
 
! style="background:#3399ff;" | <font color=#ffffff> 2) Light Higgs search A0 -> mu+mu- </font>
 
|}
 
|}
−
 
−
 
 
''' Supervisors:''' Wouter Hulsbergen (staf), Pieter David (PhD)
 
''' Supervisors:''' Wouter Hulsbergen (staf), Pieter David (PhD)
−
 
−
 
 
''' Research description: '''
 
''' Research description: '''
−
 
 
Supersymmetry is potentially the key to understand the Dark Matter in the Universe.
 
Supersymmetry is potentially the key to understand the Dark Matter in the Universe.
 
In supersymmetry, there is not just one Higgs boson as in the Standard Model,
 
In supersymmetry, there is not just one Higgs boson as in the Standard Model,
Line 117: Line 482:
 
This is a new project, within the small group at Nikhef (~3 persons). The analysis resembles the search for the
 
This is a new project, within the small group at Nikhef (~3 persons). The analysis resembles the search for the
 
decay Bs->mu+mu-, which was discovered this Summer and led to a lot of attention.
 
decay Bs->mu+mu-, which was discovered this Summer and led to a lot of attention.
−
 
  
 
''' Relevant information: '''
 
''' Relevant information: '''
−
 
 
LHCb collaboration, arXiv:1307.5024
 
LHCb collaboration, arXiv:1307.5024
 
[http://arxiv.org/pdf/1307.5024.pdf Measurement of the B0s->mu+mu- branching fraction and search for B0->mu+mu- decays at the LHCb experiment]
 
[http://arxiv.org/pdf/1307.5024.pdf Measurement of the B0s->mu+mu- branching fraction and search for B0->mu+mu- decays at the LHCb experiment]
  
 
End comment Marcel -->
 
End comment Marcel -->
 +
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 +
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<!-- Commented out Marcel 2014
 
<!-- Commented out Marcel 2014
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
Line 133: Line 498:
  
 
''' Supervisors:''' Gerhard Raven (staf), Vasilis Syropoulos (PhD)
 
''' Supervisors:''' Gerhard Raven (staf), Vasilis Syropoulos (PhD)
−
 
−
 
 
''' Research description: '''
 
''' Research description: '''
  
Line 149: Line 512:
 
This is a project that is closely related to the larger effort at Nikhef (~5 people) of measuring phi_s with
 
This is a project that is closely related to the larger effort at Nikhef (~5 people) of measuring phi_s with
 
Bs->J/psiPhi decays. Weekly video meetings with CERN coordinate the efforts within the LHCb collaboration.
 
Bs->J/psiPhi decays. Weekly video meetings with CERN coordinate the efforts within the LHCb collaboration.
−
 
  
 
''' Relevant information: '''
 
''' Relevant information: '''
Line 157: Line 519:
  
 
End comment Marcel -->
 
End comment Marcel -->
 +
<!-- ################################################# -->
  
 +
<!-- ################################################# -->
 
<!-- Commented out Nov 2014 by Niels (Georgios is on this project)
 
<!-- Commented out Nov 2014 by Niels (Georgios is on this project)
  
Line 164: Line 528:
 
! style="background:#3399ff;" | <font color=#ffffff> 2) Searching for Lorentz Invariance Violation with Bs -> J/psi phi decays </font>
 
! style="background:#3399ff;" | <font color=#ffffff> 2) Searching for Lorentz Invariance Violation with Bs -> J/psi phi decays </font>
 
|}
 
|}
−
 
−
 
 
''' Supervisors:''' Gerhard Raven (staf), Jeroen van Tilburg (Postdoc)
 
''' Supervisors:''' Gerhard Raven (staf), Jeroen van Tilburg (Postdoc)
−
 
−
 
 
''' Research description: '''
 
''' Research description: '''
  
Line 177: Line 537:
 
This is a project that is closely related to the larger effort at Nikhef (~5 people) of measuring phi_s with
 
This is a project that is closely related to the larger effort at Nikhef (~5 people) of measuring phi_s with
 
Bs->J/psiPhi decays. Weekly video meetings with CERN coordinate the efforts within the LHCb collaboration.
 
Bs->J/psiPhi decays. Weekly video meetings with CERN coordinate the efforts within the LHCb collaboration.
−
 
  
 
''' Relevant information: '''
 
''' Relevant information: '''
−
 
 
Belle Collaboration: arXiv:1203.0930v2,
 
Belle Collaboration: arXiv:1203.0930v2,
 
[http://arxiv.org/pdf/1203.0930.pdf  Search for Time-Dependent CPT Violation in Hadronic and Semileptonic B Decays]
 
[http://arxiv.org/pdf/1203.0930.pdf  Search for Time-Dependent CPT Violation in Hadronic and Semileptonic B Decays]
  
 
End comment Niels Nov 2014 -->
 
End comment Niels Nov 2014 -->
 +
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 +
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<!-- Comment Marcel 2014
 
<!-- Comment Marcel 2014
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
Line 193: Line 553:
  
 
''' Supervisors:''' Francesco Dettori (postdoc), Antonio Pellegrino (staf), Siim Tolk (PhD)
 
''' Supervisors:''' Francesco Dettori (postdoc), Antonio Pellegrino (staf), Siim Tolk (PhD)
−
 
−
 
 
''' Research description: '''
 
''' Research description: '''
−
 
 
The decay Sigma+ -> p mu mu is very rare in the Standard Model. In 2005 the  
 
The decay Sigma+ -> p mu mu is very rare in the Standard Model. In 2005 the  
 
HyperCP experiment has seen first evidence of this decay, but with a very peculiar  
 
HyperCP experiment has seen first evidence of this decay, but with a very peculiar  
Line 208: Line 565:
 
Python macros are used. This is a small project, where the student can perform  
 
Python macros are used. This is a small project, where the student can perform  
 
his research in an independent way.  
 
his research in an independent way.  
−
 
 
This research will likely result in an official LHCb publication.
 
This research will likely result in an official LHCb publication.
−
 
  
 
''' Relevant information: '''
 
''' Relevant information: '''
  
−
HyperCP Collaboration, Phys. Rev. Lett. 94, 021801 (2005)
+
[1] HyperCP Collaboration, Phys. Rev. Lett. 94, 021801 (2005)
 
[http://arxiv.org/abs/hep-ex/0501014 Evidence for the decay Sigma+ -> p mu mu]
 
[http://arxiv.org/abs/hep-ex/0501014 Evidence for the decay Sigma+ -> p mu mu]
−
 
+
[2] X.-G. He, J. Tandean, G. Valencia, Phys. Rev. Lett. 98, 081802 (2007)
−
X.-G. He, J. Tandean, G. Valencia, Phys. Rev. Lett. 98, 081802 (2007)
 
 
[http://arxiv.org/abs/hep-ph/0610362 Has HyperCP Observed a Light Higgs Boson?]
 
[http://arxiv.org/abs/hep-ph/0610362 Has HyperCP Observed a Light Higgs Boson?]
  
 
End comment Marcel -->
 
End comment Marcel -->
 +
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−
 
+
<!-- ################################################# -->
−
 
+
<!-- Commented out Marcel April 2016
−
 
 
  
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
Line 230: Line 584:
 
! style="background:#3399ff;" | <font color=#ffffff> 1) Bs->mumu and Bd->mumu normalization and B mesons hadronization probabilities </font>
 
! style="background:#3399ff;" | <font color=#ffffff> 1) Bs->mumu and Bd->mumu normalization and B mesons hadronization probabilities </font>
 
|}
 
|}
−
 
 
''' Supervisors:''' Antonio Pellegrino (staff), Maarten van Veghel (PhD)
 
''' Supervisors:''' Antonio Pellegrino (staff), Maarten van Veghel (PhD)
−
 
 
''' Research description: '''
 
''' Research description: '''
  
Line 238: Line 590:
 
is one of the flagships of the LHCb experiment, the latest result in
 
is one of the flagships of the LHCb experiment, the latest result in
 
combination with CMS has recently been published on Nature.
 
combination with CMS has recently been published on Nature.
−
The aim of this project is to study the yields of other decays
+
The aim of this project is to study one of the main uncertainties in the
 +
measurements of the branching fractions by measuring the yields of other decays
 
with a J/Psi in the final state, like B+ -> J/Psi K+ and  Bs-> J/Psi Phi,
 
with a J/Psi in the final state, like B+ -> J/Psi K+ and  Bs-> J/Psi Phi,
 
that can be detected triggering on the muons decay products of the J/Psi.
 
that can be detected triggering on the muons decay products of the J/Psi.
 
These yields are a crucial input to obtain the Bs-> mu mu and Bd->mu mu decays
 
These yields are a crucial input to obtain the Bs-> mu mu and Bd->mu mu decays
−
branching fraction as they provide a relative normalization.
+
branching fractions as they provide a relative normalization.
 
Moreover, in order to use Bd decays to normalize the Bs-> mu mu yields
 
Moreover, in order to use Bd decays to normalize the Bs-> mu mu yields
 
we need to measure the relative probabilities for a b quark to hadronize
 
we need to measure the relative probabilities for a b quark to hadronize
Line 261: Line 614:
  
 
''' Relevant information: '''
 
''' Relevant information: '''
−
 
 
[1] R.Aaij et al. [LHCb Collaboration], ``Measurement of the fragmentation fraction ratio f_s/f_d and its
 
[1] R.Aaij et al. [LHCb Collaboration], ``Measurement of the fragmentation fraction ratio f_s/f_d and its
 
dependence on B meson kinematics'', JHEP 04 (2013) 001 [arXiv:1301.5286 [hep-ph]].
 
dependence on B meson kinematics'', JHEP 04 (2013) 001 [arXiv:1301.5286 [hep-ph]].
  
 +
End comment Marcel April 2016 -->
 +
<!-- ################################################# -->
 +
 +
 +
<!-- ################################################# -->
 
<!-- Commented out May 2015 by Niels (Siim, Maarten, Mick already on the project)
 
<!-- Commented out May 2015 by Niels (Siim, Maarten, Mick already on the project)
−
 
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
 
! style="background:#3399ff;" | <font color=#ffffff> 3) Measurement of pt and eta dependence of B0 and Bs0 production </font>
 
! style="background:#3399ff;" | <font color=#ffffff> 3) Measurement of pt and eta dependence of B0 and Bs0 production </font>
 
|}
 
|}
−
 
 
''' Supervisors:''' Niels Tuning (staf), ... ?
 
''' Supervisors:''' Niels Tuning (staf), ... ?
−
 
 
''' Research description: '''
 
''' Research description: '''
−
 
 
The relative production fractions ("fs/fd") of B0 (with quark content bd) and Bs0 (with quark content bs)
 
The relative production fractions ("fs/fd") of B0 (with quark content bd) and Bs0 (with quark content bs)
 
mesons is crucial for the determination of the branching fraction of any Bs0 decay at the LHC. The most
 
mesons is crucial for the determination of the branching fraction of any Bs0 decay at the LHC. The most
Line 291: Line 644:
  
 
''' Relevant information: '''
 
''' Relevant information: '''
−
 
 
[1] R.Aaij et al. [LHCb Collaboration], ``Measurement of the fragmentation fraction ratio f_s/f_d and its
 
[1] R.Aaij et al. [LHCb Collaboration], ``Measurement of the fragmentation fraction ratio f_s/f_d and its
 
dependence on B meson kinematics'', JHEP 04 (2013) 001 [arXiv:1301.5286 [hep-ph]].
 
dependence on B meson kinematics'', JHEP 04 (2013) 001 [arXiv:1301.5286 [hep-ph]].
−
 
 
[2] R.Aaij et al. [LHCb Collaboration], ''Measurement of the B0s??+?? branching fraction and search for
 
[2] R.Aaij et al. [LHCb Collaboration], ''Measurement of the B0s??+?? branching fraction and search for
 
B0??+?? decays at the LHCb experiment'', Phys.Rev.Lett. 111 (2013) 101805  [arXiv:1307.5024 [hep-ph]]
 
B0??+?? decays at the LHCb experiment'', Phys.Rev.Lett. 111 (2013) 101805  [arXiv:1307.5024 [hep-ph]]
  
 
End comment Niels May 2015-->
 
End comment Niels May 2015-->
−
 
+
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−
{| border="1" cellpadding="2" cellspacing="0"
 
−
|-
 
−
! style="background:#3399ff;" | <font color=#ffffff> 2) Measurement of BR(B0->pi-Ds+) and BR(Bs->Ds-*pi+)/BR(Bs->Ds-pi+) </font>
 
−
|}
 
−
 
 
−
''' Supervisors:''' Niels Tuning (staff), Lennaert Bel (PhD) , Mick Mulder (PhD)
 
−
 
 
−
''' Research description: '''
 
−
 
 
−
This project aims to measure the branching fraction of the decay B0->pi-Ds+.
 
−
The decay B0->pi-Ds+ is quite rare, because it occurs through the transition of a b-quark
 
−
to a u-quark. It has been measured at the B-factories only at modest precision (~12%).
 
−
This decay is interesting, because <br>
 
−
1) It is sensitive to the CKM-element Vub, which determination is heavily debated.<br>
 
−
2) It can be used to determine the ratio r_pi=B0->pi-D+/B0->D-pi+ which in turn is needed for CP violation measurements.<br>
 
−
3) It can quantify non-factorisable QCD effects in certain B-decays.
 
−
 
 
−
The experimental challenge is to understand the background from e.g. Bs->Ds*pi decays.
 
−
The aim is to also determine the relative branching fraction of  Bs->Ds*pi relative to Bs->Dspi decays.
 
−
This can is useful, because <br>
 
−
1) It helps in the measurement of B0->pi-Ds+ <br>
 
−
2) It might quantify the magnitude of the ratio of form factors F(Bs->Ds*)/F(Bs->Ds*)
 
−
 
−
The aim is that this project results in a journal publication on behalf of the LHCb collaboration.
 
−
For this project computer skills are needed.
 
−
The ROOT programme and C++ and/or Python macros are used.
 
−
This is a project that is closely related to three important analyses in the group: <br>
 
−
1) Measurements of fs/fd with hadronic Bs->DsPi decays, <br>
 
−
2) Time dependent CP violation analysis of Bs->DsK decays. <br>
 
−
Weekly video meetings with CERN coordinate the efforts with in the LHCb collaboration.
 
−
 
 
−
''' Relevant information: '''
 
−
 
 
−
[1] R.Aaij et al. [LHCb Collaboration],
 
−
``Determination of the branching fractions of B0s->DsK and B0->DsK'',
 
−
Submitted to JHEP [arXiv:1412.7654 [hep-ex]].
 
−
 
 
−
[2] R. Fleischer, N. Serra and N. Tuning,
 
−
``Tests of Factorization and SU(3) Relations in B Decays into Heavy-Light Final States'',
 
−
Phys. Rev. D 83, 014017 (2011) [arXiv:1012.2784 [hep-ph]].
 
−
 
 
−
[3] K. de Bruyn, R. Fleischer, R. Knegjens, M. Merk, M. Schiller and N. Tuning,
 
−
``Exploring Bs -> Ds(*)K Decays in the Presence of a Sizable Width Difference ??s'',
 
−
Nucl. Phys. B 868, 351 (2013) [arXiv:1208.6463 [hep-ph]].
 
  
  
 +
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 +
<!-- Commented out Marcel April 2016
  
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
Line 355: Line 664:
  
 
''' Research description: '''
 
''' Research description: '''
 +
 
At the LHC, B0 mesons and anti-B0 mesons are not produced in equal quantities (about 0.5% more B0 mesons than anti-B0 mesons).  
 
At the LHC, B0 mesons and anti-B0 mesons are not produced in equal quantities (about 0.5% more B0 mesons than anti-B0 mesons).  
 
This production asymmetry can be measured with semileptonic decays of the type B0 -> D-(*) mu+ nu (and its charge conjugate decay).  
 
This production asymmetry can be measured with semileptonic decays of the type B0 -> D-(*) mu+ nu (and its charge conjugate decay).  
Line 360: Line 670:
 
This requires to unfold of the observed kinematic distributions.
 
This requires to unfold of the observed kinematic distributions.
  
 +
End comment Marcel April 2016 -->
 +
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−
 
+
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−
{| border="1" cellpadding="2" cellspacing="0"
+
<!-- Commented out Marcel April 2016
−
|-
 
−
! style="background:#3399ff;" | <font color=#ffffff> 4) A search for heavy neutrinos in the decay of W at LHCb  </font>
 
−
|}
 
−
 
 
−
''' Supervisors:''' Wouter Hulsbergen (staff), Elena Dall'Occo (PhD)
 
−
''' Research description: '''
 
−
Neutrinos are arguably the most mysterious of all known fundamental fermions as they are both much lighter than all others and only weakly interacting.
 
−
It is thought that the tiny mass of neutrinos can be explained by their mixing with so-far unknown, much heavier, neutrino-like particles.
 
−
In this research proposal we look for these new neutrinos in the decay of the SM W-boson using data with the LHCb experiment at CERN.
 
−
The W boson is assumed to decay to a heavy neutrino and a muon. The heavy neutrino subsequently decays to a muon and a pair of quarks.
 
−
Both like-sign and opposite-sign muon pairs will be studied. The result of the analysis will either be a limit on the production of the new neutrinos
 
−
or the discovery of something entirely new.
 
−
 
 
−
 
 
−
 
 
 
{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
Line 384: Line 681:
  
 
''' Supervisors:''' Jeroen can Tilburg (Vidi Laureate)
 
''' Supervisors:''' Jeroen can Tilburg (Vidi Laureate)
−
 
 
''' Research description: '''
 
''' Research description: '''
 
When two particles are created in an anti-symmetric wave function, the two particles are entangled, even though they may be separated by large distances.  
 
When two particles are created in an anti-symmetric wave function, the two particles are entangled, even though they may be separated by large distances.  
Line 391: Line 687:
 
it is possible to measure this decoherence parameter by counting the number of phi decays where both neutral kaons are measured as K_S-> pi+ pi-.  
 
it is possible to measure this decoherence parameter by counting the number of phi decays where both neutral kaons are measured as K_S-> pi+ pi-.  
 
If this parameter is measured to be non-zero, it would mean that our current understanding of quantum mechanics is not complete.
 
If this parameter is measured to be non-zero, it would mean that our current understanding of quantum mechanics is not complete.
 +
 +
End Comment Marcel April 2016-->
 +
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Latest revision as of 13:11, 15 February 2021

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