Particle physics @ CPT - Jérôme Charles for the PP team
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Particle physics @ CPT
Jérôme Charles for the PP team
CPT Marseille
Faculté
des Sciences
Jérôme Charles P3TMA presentation, 6 September 2016
The PP team
Permanent members: Aoife Bharucha, Jérôme Charles, Marc Knecht,
Laurent Lellouch, Eduardo de Rafael (emeritus)
Postdocs: N. Desai, K. Miura, A. Tayduganov, C. Torrero
PhD students: N. Bizot (co-direction), C. Meaux (co-direction)
Collaborations: CPPM, Montpellier, Paris, Orsay, Germany, Hungary,
Japan, Spain, USA, . . .
Keywords: physics of quarks and of CP violation, nonperturbative
dynamics of QCD and possibly of EWSB, revealing new fundamental
physics
Jérôme Charles P3TMA presentation, 6 September 2016
Current situation in particle physics
Discovery of Higgs LHC in 2012 → we now have a complete Standard
Model (SM)
Describes nature extraordinarily well . . .
. . . but leaves many questions unanswered: nature of Dark Matter, origin
of CP violation needed to explain baryogenesis, apparent insensitivity of
Higgs mass to possibly very large new physics scales, . . .
. . . and there is room for new physics
In this context, we are interested in testing the SM, in revealing new
physics and in addressing some of these questions
Jérôme Charles P3TMA presentation, 6 September 2016
Quark flavor mixing and tests of SM
Unitary CKM matrix
d s b
b λ
Aλ3 (ρ̄ − i η̄)
W u 1− 2
λ
Vub
→V = c −λ 1− λ
Aλ2 + O(λ4 )
2
u
t Aλ3 (1 − ρ̄ − i η̄) −Aλ2 1
⇒ many possible tests of flavor mixing, CP violation and quark-lepton
universality through redundant measurements
0.7
e.g. unitarity triangle:
excluded area has CL > 0.95
∆md & ∆ms εK CKM
fitter
0.6 γ ∆md Winter 14
2 Vud V ∗ V V∗
Gq 2
ub + ud ub = O MW
0.5 sin 2β
∗
sol. w/ cos 2β < 0
Vcd Vcb 1 + (excl. at CL > 0.95)
2
Gµ Vcd V ∗ Vcd V ∗ Λ2 0.4
cb cb NP
η
Vub α
0.3 εK τν
α
0.2
If triangle fails to close ⇒ new physics 0.1
α
γ
Vub
SL β
0.0
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
Today, excellent agreement between ρ
experiment and SM, but . . . (J. Charles et al)
(relies also on calculations by A. Bharucha et al & L. Lellouch et al)
Jérôme Charles P3TMA presentation, 6 September 2016
Quark flavor and new physics
(J. Charles, A. Tayduganov and CKMfitter group)
. . . there is still room for new sources of flavor mixing and CP violation
FCNC → new particles in loops affect observables, even at low energies
b W+ d
Bd0 u, c, t B̄d0
d W− b
d d
× 1 + hd e2iσd
M12 = (M12 )SM
p-value
1.0
3.0 excluded area has CL > 0.95
CKM
fitter
2013
0.9 Very rare in SM (loop and helicity suppression)
2.5 0.8
0.7
B(Bs0 → µ+ µ− ) = (3.65 ± 0.23) × 10−9
2.0
0.6
Measured recently by LHCb (CPPM) (. . . A.
σd
0.5
1.5
0.4
Mordá et al, PRL 2013 +Nature 2015)
1.0
0.3 B(Bs0 → µ+ µ− ) = 2.8+0.7
−0.6 × 10
−9
0.2
0.5
0.1
→ no big effects, but many more rare modes to
0.0
0.0 0.1 0.2 0.3 0.4 0.5
0.0 0 → τ +τ −, B → K ∗τ +τ −, . . . )
measure (Bd,s
hd
(J. Charles et al.) where new physics could appear (J. Charles,
A. Tayduganov et al)
Jérôme Charles P3TMA presentation, 6 September 2016
Light quarks at low energies
(L. Lellouch, R. Malak, K. Miura, T. Métivet, C. Torrero et al)
Motivations:
Understand and describe ordinary (and less ordinary) matter from first principles
Compute low-energy strong interaction effects in fundamental theory to help
reveal new physics
Challenges:
Quarks are elementary quantum excitations . . . but they only appear, confined in
hadrons
Confinement due to highly non-linear interactions in QCD at low energy
To describe ordinary matter, QCD requires > 100 numbers at every point of
spacetime
→ ∞ number of numbers in our continuous spacetime
⇒ must temporarily “simplify” the theory to be able to calculate (regularization)
Only known way to compute these interactions in fundamental theory is numerical
→ Lattice QCD
Jérôme Charles P3TMA presentation, 6 September 2016
What is lattice QCD?
Lattice gauge theory −→ mathematically sound definition of NP QCD:
Uµ (x) = eiagAµ (x) ψ(x)
UV (and IR) cutoffs and a well defined path 6r r r r r r r r
integral in Euclidean spacetime: r r r r r r r a
r ?
6
Z r r r r r r r r
r r r r r r r r
R
hOi = DUDψ̄Dψ e−SG − ψ̄D[M]ψ O[U, ψ, ψ̄]
T r r r rr r r r
r r6 r
r r r - r r
Z
−SG ?
= DU e det(D[M]) O[U]Wick
r r r r r r r r
r r r r r r r r
r r r r r r r r
DUe−SG det(D[M]) ≥ 0 and finite # of dof’s ?r r r r r r r r
→ evaluate numerically using stochastic -
methods L
NOT A MODEL: LQCD is QCD when a → 0, V → ∞ and stats → ∞
HUGE CHALLENGE: integral and determinant with O(109 ) dofs!
⇒ need some of the world’s largest supercomputers
Jérôme Charles P3TMA presentation, 6 September 2016
Mass and stability of ordinary matter
(Budapest-Marseille-Wuppertal collaboration)
Origin of mass Stability and existence
> 99% of mass of visible universe is in the In Nature (MN = (Mn + Mp )/2):
form of p & n ∆MN ≡ Mn − Mp = 0.14% × MN
mass of quarks contributes < 2% to mass Tiny, but hugely important for
of p & n stability of matter
→ light hadron masses generated by QCD Big Bang nucleosynthesis
energy imparted to q & g via m = E/c 2
Subtle cancellation between EM and
Higgs “only” responsible for quark mass (md − mu ) effects mixed w/ QCD
contribution!
Conceptual and numerical challenge to
include these effects
2000
-
Σ -
+ Ω
Σ
1500
0
+ 40 Ξ
K Σ
M[MeV]
+ 40
1000 K
±
N Ξ
-
+ 40
+ 40
0
Ξ
500 K n
experiment
p input
QCD (2008)
π
±
QCD+QED
0
(BMW, Science 2008) (BMW, Science 2015)
Jérôme Charles P3TMA presentation, 6 September 2016
Direct Dark Matter searches
(L. Lellouch, Th. Métivet, C. Torrero et al)
> 84% of the mass of the universe is in the form of DM
Weakly Interacting Massive Particles (WIMPs) are
possible candidates
Many experiments are trying to observe them directly
(LUX, XENON, CDMS, PICASSO, . . . )
With colleagues from Montpellier (LUPM)
and Marseille (LAM), investigate and reduce
astrophysical and hadronic uncertainties in
interpreting possible DM signals
Use astrophysical phenomenology,
cosmological simulations and lattice QCD
LQCD needed to translate fundamental χ-q
to measured χ-N coupling
Jérôme Charles P3TMA presentation, 6 September 2016
High energy new physics at the LHC
(A. Bharucha, N. Desai and collaboration with Montpellier)
Strong case for new states with electroweak interactions at the TeV
scale (hierarchy problem and WIMP dark matter)
A real challenge to constrain or detect these new particles at the LHC
Investigate well-motivated models of new physics, in order to obtain
bounds on these models as well as to make predictions for the future
discovery reach of LHC and of direct matter searches
To this aim, use analytical and numerical tools to simulate experimental
events as can be observed by the LHC
Jérôme Charles P3TMA presentation, 6 September 2016Anomalous magnetic moment of the muon
(M. Knecht, L. Lellouch, R. Malak, K. Miura, E. de Rafael)
Quantum effects give small corrections to Dirac eqn. prediction aµ ≡ (gµ − 2) = 0 for
gyromagnetic ratio of muon
Significant disagreement between experiment and SM: (Davier et al ’11, E821 ’06, PDG ’12)
∆aµ ≡ aµexp − aµSM = 28.7(8.0) × 10−10 [3.6 σ]
w/ (σa SM = 4.9 × 10−10 ) ' (σaµexp = 6.3 × 10−10 ) [0.5 ppm]
µ
E821 (Fermilab) & g−2/EDM (J-PARC) & expect σaµexp /4
⇒ potentially large signal for BSM physics . . . but theory has to follow
process SM × 1010
aµ σ SM × 1010
aµ
QED (leptons) 11658471.809 0.015
HVP (LO) 692.3 4.2 ⇐
EW 15.4 0.2
HLbyL 10.5 2.6 ⇐
HVP (NLO) −9.79 0.09
⇒ σa SM dominated by HVP (LO) and HLbyL
µ
→ require reliable computation of nonperturbative QCD
effects (e.g. Lattice QCD, phenomenology)
→ must understand potential discrepancies in terms of new
physics scenarios
→ collaboration with colleagues from Montpellier
Jérôme Charles P3TMA presentation, 6 September 2016Seminar, computing, masters and Ph.D. projects
Classes taught:
QFT (L. Lellouch)
Advanced QFT (M. Knecht)
Seminar, computing, master and PhD projects: several possibilities related to the
projects presented here
If you are interested, come and see us!
Our team is part of an Excellence Laboratory in
Astroparticle Physics, Cosmology and Particle Physics
(Marseille, Montpellier, Toulouse)
Jérôme Charles P3TMA presentation, 6 September 2016You can also read
