Difference between revisions of "Master student Projects"

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'''Supervisor''' : Mara Soares (staff), Emmy Gabriel (postdoc) Michele Veronesi (PhD)
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'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
  
 
'''Research Description:'''
 
'''Research Description:'''
  
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The decay B0->D-pi+ is very abundant in LHCb, and therefore ideal to study the oscillation frequency
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delta md, with which B0 mesons oscillate into anti-B0 mesons, and vice versa.
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This process proceeds through a so-called box diagram which might hide new yet-undiscovered particles.
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Recently, it has been realized that value of delta md is in tension with the valu of CKM-angle gamma,
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triggering renewed interest in this measurement.
  
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Our group at Nikhef has 10 years experience in the analysis of B->Dh decays.
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This analysis may lead to a publication on behalf of the LHCb collaboration.
  
 
''' Relevant information: '''
 
''' Relevant information: '''
  
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[1]  [https://arxiv.org/abs/1210.6750 arXiv:1210.6750]
 
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Measurement of the B0--B�0 oscillation frequency ?md with the decays B0?D??+ and B0?J/?K?0
 
  
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[2] [https://arxiv.org/abs/1805.03448 arXiv:1805.03448]
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[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
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Measurement of CP violation in B0?D??� decays
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[2] [https://arxiv.org/abs/1911.07856 arXiv:1911.07856] D. King, A. Lenz, Th. Rauh, |Vcb| and gamma from mixing
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[3] [https://indico.nikhef.nl/event/1379/contribution/1/material/slides/0.pdf talk] N. Tuning, CKM unitarity and B mixing
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[4]  [https://arxiv.org/abs/1210.6750 arXiv:1210.6750] LHCb coll.,
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Measurement of the B0--B�0 oscillation frequency delta md with the decays B0->D-pi+ and B0->J/psiK*0
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[5] [https://arxiv.org/abs/1805.03448 arXiv:1805.03448] LHCb coll.,
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Measurement of CP violation in B0->D�pi� decays
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{| 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)
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'''Research Description:'''
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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.
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Our group at Nikhef has 10 years experience in the analysis of B->Dh decays.
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This analysis may lead to a publication on behalf of the LHCb collaboration.
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''' Relevant information: '''
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[1]  [https://arxiv.org/abs/1603.04804 arXiv:1603.04804] LHCb coll.,
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Search for violations of Lorentz invariance and CPT symmetry in B0(s) mixing
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[2] [https://arxiv.org/abs/1407.1269 arXiv:1407.1269] J. van Tilburg and M. van Veghel,
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Status and prospects for CPT and Lorentz invariance violation searches in neutral meson mixing
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{| border="1" cellpadding="2" cellspacing="0"
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|-
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! style="background:#3399ff;" | <font color=#ffffff> 3) BR(B0->D-pi+) and fd/fu with B+->D0pi+ </font>
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|}
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'''Supervisor''' : Niels Tuning (staff), Emmy Gabriel (postdoc), Michele Veronesi (PhD)
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'''Research Description:'''
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The abundant decay B0->D-pi+ is often used as normalization channel, given its
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clean signal, and well-known branching fraction, as measured by the B-factories.
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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.
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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.
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Our group at Nikhef has 10 years experience in the analysis of B->Dh decays.
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This analysis may lead to a publication on behalf of the LHCb collaboration.
 +
 
 +
''' Relevant information: '''
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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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Branching fraction measurement of B0->D+s pi?
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! style="background:#3399ff;" | <font color=#ffffff> 1) Searches for new pentaquarks </font>
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! style="background:#3399ff;" | <font color=#ffffff> 5) Searches for new pentaquarks </font>
 
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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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! 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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! style="background:#3399ff;" | <font color=#ffffff> 11) Measurement of Central Exclusive Production Rates of Chi_c using converted photons in LHCb. </font>
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! 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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! 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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! 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.
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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)
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'''Research Description:'''
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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
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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:
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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,
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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.
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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
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candidate. Machine learning techniques could be explored.
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''' Relevant information: '''
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[1]  [https://arxiv.org/abs/1903.09252 arXiv:1903.09252] LHCb coll., Search for lepton-universality violation in B+?K+l+l?decays
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[2]  [https://arxiv.org/abs/1705.05802 arXiv:1903.09252] LHCb coll., Test of lepton universality with B0?K*0l+l? decays
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[3]  [https://arxiv.org/abs/1912.08139 arXiv:1912.08139] LHCb coll., Test of lepton universality with ?b?pKl+l? decays
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[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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Latest revision as of 13:11, 15 February 2021

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