Chris ParkesUniversity of Manchester
QUARK FLAVOUR PHYSICS
Part VI
Concluding Remarks
1) Other flavour physics / CPV searches
2) Overall Constraints on CKM Triangle
Spectroscopy:
X(3872)
Other areas of measurements made by quark flavour experiments
not discussed yet: Spectroscopy
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X(3872) : Exotic StateAn area of quark flavour physics we haven’t discussed is searching for new meson states
Mesons: quark, anti-quark
Baryons: 3 quarks
50 year history of searching for ‘exotic’ states
Belle discovered X(3872 MeV)
10 years ago, didn’t match any predicted mass state for a charm meson
Subsequently a number of other states that don’t “fit” have been found
LHCb 2013 – Measured JPC=1++ from analysing angles of decay products
All but rules out that it is a conventional meson
Possible exotic explanations of the X(3872) nature include:
tetra-quark : di-quark di-anti-quark; or charmonium-’molecule’ mixture.
Dipole Moments
Other type of measurements sensitive to CP violation in quarks but not
made by accelerator-based quark flavour experiments
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Spin reverses under T
Dipole moment reverses under P
So another way of finding CP Violation
(and another good LHCb PhD thesis topic…)
ii
ie rd
Neutron Electric Dipole Moments
Spin precession frequency of ultracold neutrons
in a weak magnetic field.
1.Take neutrons from reactor at ILL
2. Slow them down and store (100s)
3. Apply weak magnetic field
neutron spin precesses in magnetic field due to magnetic moment of neutron
4. strong electric field is applied also
If an EDM this will interact and spin precession will speed up or slow down
5. Measure precession with NMR
Experiment at IIL, Grenoble from Sussex, RAL et al.
Initially rom temp, now cryo. expt
CKM
Measuring Parameters
Triangle – Overall Fits
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tbtstd
cbcscd
ubusud
VVV
VVV
VVV
CKM metrology
|Vud| : nuclear b-decay ~ (0.97380.0003) |Vus| : semileptonic kaon decays ~ (0.2260.002)
|Vud| : nuclear b-decay ~ (0.97380.0003) |Vus| : semileptonic kaon decays ~ (0.2260.002)
How are the CKM parameters magnitudes (not phases) measured? Magnitudes are typically determined from (ratios of) decay rates
E.g. compare decay rates of neutron and muon decays ( Vud2)
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Remember unitarity constraints – e.g.
so can constrain for further generations of quarks from magnitudes only
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CKM metrology – constraints in the (r, h) plane
K 2sin
cbub VV
Taken from the UTfit homepage: http://www.utfit.org
Kaons CPV B CPV B magnitudes only
sd mm
B Mixing
angle
B CPV
B CPV
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CKM metrology and unitarity triangle fit
CKM Mechanism in SM proven to work
Now a good way to discover new physics
Over constraining triangle and compatibility of angle measurements
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CKM metrology and UnitarityTriangle: Current Status
There is still compatibility with the Standard Model !
Constraints from many CKM matrix
complementary and independent
measurements
There is still compatibility with the Standard Model !
Constraints from many CKM matrix
complementary and independent
measurements
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Concluding remarks
CP violation is a fundamental broken symmetry
Needed for matter anti-matter asymmetry
It can be incorporated in the Standard Model,
but seems like an “add-on”
SM cannot be the final answer
nowhere near enough CP Violation in quark sector
Study of CP violation involves precise measurements
of the CKM matrix
Present measurements allow to over-constrainthe CKM triangles and look for inconsistencies
Inconsistencies would be a sign for New Physics
And rare decays also an important method for searching for New Physics
A lot of hope and expectation for the (near) future experimental results!