Difference between revisions of "Master student Projects"

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=== Master projects in the Nikhef B-physics group ===
 
=== Master projects in the Nikhef B-physics group ===
  
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|-
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! style="background:#3399ff;" | <font color=#ffffff> 1) Title </font>
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'''Supervisor''' : S.Taff (staff)
 +
 +
'''Research Description:'''
 +
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Abstract
 +
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''' Relevant information: '''
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[1]  [https://arxiv.org/abs/1507.03414 arXiv:1507.03414] (thesis or paper)
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{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 1) Searches for new pentaquarks </font>
+
! style="background:#3399ff;" | <font color=#ffffff> 1) Measurement of delta md </font>
 
|}
 
|}
  
−
'''Supervisor''' : P. Koppenburg (staff)
+
'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
  
 
'''Research Description:'''
 
'''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.  
+
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: '''
 
''' 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).
+
[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"
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|-
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! style="background:#3399ff;" | <font color=#ffffff> 2) Searching for CPT violation </font>
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|}
 +
 
 +
'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
 +
 
 +
'''Research Description:'''
 +
 
 +
CPT symmetry is closely linked to Lorentz symmetry, and any violation
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would revolutionize science. There are possibilities though that supergravity could
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cause CPT violating effects in the system of neutral mesons.
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The precise study of B0s oscillations in the abundant Bs->Dspi decays can
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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"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 5) A Scintillator Fibers Tracker </font>
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! style="background:#3399ff;" | <font color=#ffffff> 3) BR(B0->D-pi+) and fd/fu with B+->D0pi+ </font>
 
|}
 
|}
  
−
''' Supervisors:''' Antonio Pellegrino
+
'''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
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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,
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based on isospin symmetry. The study of B+->D0pi+ and B0->D-pi+ allows for the
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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.
  
−
''' Research description: '''
+
''' Relevant information: '''
  
−
The LHCb collaboration is upgrading the present tracking system
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[1]  [https://cds.cern.ch/record/2636716/files/CERN-THESIS-2018-137.pdf CERN-THESIS-2018-137] J. Butter,  
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constructing a new tracker based on scintillating fibers combined
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Branching fraction measurement of B0->D+s pi?
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with silicon photo-multipliers (SiPM): the SciFi Tracker!
 
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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.
 
  
  
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{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
−
! style="background:#3399ff;" | <font color=#ffffff> 6) The Z forward backward asymmetry </font>
+
! style="background:#3399ff;" | <font color=#ffffff> 5) Searches for new pentaquarks </font>
 
|}
 
|}
  
−
''' Supervisors:''' Wouter Hulsbergen
+
'''Supervisor''' : P. Koppenburg (staff)
 +
 
 +
'''Research Description:'''
  
−
''' 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.
  
−
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.
+
''' 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"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 9) Measurement of the relative efficiency of muons and electrons with J/psi->ll decays </font>
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! style="background:#3399ff;" | <font color=#ffffff> 6) Measurement of the relative efficiency of muons and electrons with J/psi->ll decays </font>
 
|}
 
|}
  
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{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 10) Very rare decays of B mesons</font>
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! style="background:#3399ff;" | <font color=#ffffff> 7) Very rare decays of B mesons</font>
 
|}
 
|}
  
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{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 11) Measurement of Central Exclusive Production Rates of Chi_c using converted photons in LHCb. </font>
+
! style="background:#3399ff;" | <font color=#ffffff> 8) Measurement of Central Exclusive Production Rates of Chi_c using converted photons in LHCb. </font>
 
|}
 
|}
  
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{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 12) Optimization studies for Vertex detector at the High Lumi LHCb </font>
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! style="background:#3399ff;" | <font color=#ffffff> 9) Optimization studies for Vertex detector at the High Lumi LHCb </font>
 
|}
 
|}
  
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{| border="1" cellpadding="2" cellspacing="0"
 
{| border="1" cellpadding="2" cellspacing="0"
 
|-
 
|-
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! style="background:#3399ff;" | <font color=#ffffff> 13) Measurement of charge multiplication in heavily irradiated sensors </font>
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! style="background:#3399ff;" | <font color=#ffffff> 10) Measurement of charge multiplication in heavily irradiated sensors </font>
 
|}
 
|}
  
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''' Research description: '''
 
''' 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.
 
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"
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|-
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! style="background:#3399ff;" | <font color=#ffffff> 11) Searching for lepton-universality violation with ?b ? ?l+l? decays </font>
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|}
 +
 +
'''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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<!--
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| border="1" cellpadding="2" cellspacing="0"
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|-
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! style="background:#3399ff;" | <font color=#ffffff> 5) A Scintillator Fibers Tracker </font>
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|}
 +
''' 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.
 +
-->
 +
<!-- ################################################# -->
 +
  
 
<!-- ################################################# -->
 
<!-- ################################################# -->
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''' Supervisors:''' Wouter Hulsbergen
 
''' Supervisors:''' Wouter Hulsbergen
 
''' Research description: '''
 
''' 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).
 
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).
  
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''' Supervisors:''' Wouter Hulsbergen
 
''' Supervisors:''' Wouter Hulsbergen
 
''' Research description: '''
 
''' 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"
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|-
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! 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.
  
−
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.
 
  
 
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Latest revision as of 13:11, 15 February 2021

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