1. University of Manchester
QUARK FLAVOUR PHYSICS
Chris Parkes
University of Manchester
Part VI
Concluding Remarks
Other flavour physics / CPV searches
Overall Constraints on CKM Triangle

2. Other areas of measurements made by quark flavour experiments
not discussed yet: Spectroscopy
Spectroscopy:
Z(4430)-

3. Exotic States Mesons: quark, anti-quark Baryons: 3 quarks
An 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
For example:

4. Z(4430)- : Exotic State Belle discovered X(3872 MeV) in 2014
LHCb, 2014, arXiv:
Belle discovered X(3872 MeV) in 2014
didn’t match any predicted mass state for a charm meson
Subsequently a number of other states that don’t “fit” have been found
Z(4430)- is a charged state, given its mass its minimal quark content
i.e. a four-quark state
Possible exotic explanations include:
tetra-quark : di-quark di-anti-quark; or charmonium-’molecule’ mixture.

5. Pentaquark States Invariant mass calculation using
with measured momenta
known J/Ψ, p, K masses
E, p, conservation
Clean selection – low background
Λb quark content (udb)
Study two-body mass combinations
Quark content J/Ψ (cc), p (uud)

6. Full analysis – with all known contributions to Dalitz plots included in model – shows two new states needed
Pentaquarks !

7. Other type of measurements sensitive to CP violation in quarks but not
made by accelerator-based quark flavour experiments
Dipole Moments

8. So another way of finding CP Violation
Dipole moment reverses under P
Spin reverses under T
So another way of finding CP Violation
(and another good LHCb PhD thesis topic…)

9. Neutron Electric Dipole Moments
Experiment at IIL, Grenoble from Sussex, RAL et al.
Initially rom temp, now cryo. expt
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

10. Triangle – Overall Fits
CKM
Measuring Parameters
Triangle – Overall Fits

11. CKM metrology
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)
|Vud| : nuclear b-decay
~ (0.97380.0003)
|Vus| : semileptonic kaon decays
~ (0.2260.002)

12. Remember unitarity constraints – e.g.
so can constrain for further generations of quarks from magnitudes only

13. CKM metrology – constraints in the (r, h) plane
Taken from the UTfit homepage:
Kaons CPV
B CPV
B magnitudes only
B CPV
B Mixing
B CPV

14. 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

15. CKM metrology and UnitarityTriangle: Current Status
There is still compatibility with the Standard Model !
Constraints from many CKM matrix complementary and independent measurements

16. 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-constrain the 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!