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!