AMS-02, Antimatter, Strangelets , Cosmic Rays Nicolò Masi May 2012
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Transcript of AMS-02, Antimatter, Strangelets , Cosmic Rays Nicolò Masi May 2012
AMS-02, Antimatter, Strangelets, Cosmic Rays
Nicolò Masi May 2012
Bologna University and INFN
AMS-02 and the Antiworld
Island of Antimatter?
The CPT theorem assures that any particle species there exists the antiparticle with exactly the same mass and decay width and eventually opposite charges. This striking symmetry would naturally lead us to conclude that the Universe contains particles and antiparticles in equal number densities.
The observed Universe is drastically different. We do not observe any bodies of antimatter within the solar system and only antiprotons in the cosmic rays, which are believed to be of extra solar origin. Antiprotons are likely to be produced as secondaries in collisions:
100 MeV g flux excludes wide antimatter regions up 50÷100 Mpc
Sakharov’s 3 Principles of Baryogenesis …..
… but alternative models predict distant antimatter local domains
A single anti-He CR nucleus represents a strong evidence for Antimatter Domains in our Universe: antistars, antigalaxies and cosmological remnants
We need :
- very large statistics of primary CRs
- very good particle identification, including charge sign reconstruction
Search for Antimatter
Antihelium/Helium Flux
Expected Goal for Antinuclei Search
10 years
If we reach this value we can affirm antiworld doesn’t exist
ANTIMATTER in this Universe: And if it really not
existed?
When?: Big Bang Timeline
Planck Epoch:10-44 ÷10–43 seconds after the Big Bang
Grand Unification epoch10–43 ÷10–36 seconds after the Big Bang, T ∼ 1015 GeVGravitation begins to separate from the fundamental gauge interactions. Physics may be described by GUT in which the gauge group of the Standard Model is embedded in a much larger group, which is broken to produce the observed forces of nature.
Electroweak epoch 10–36 ÷10–12 seconds after the Big Bang, T ∼ 1014 ÷103 GeVThe temperature of the universe is low enough (1028 K) to separate the strong force from the electroweak force. This phase transition triggers a period of exponential expansion known as cosmic inflation. After inflation ends, particle interactions are still energetic enough to create large numbers of exotic particles, including W, Z and H.
Inflationary epoch10–36 ÷10–32 seconds after the Big Bang, T ≲ 1013 GeVThe universe is flattened (its spatial curvature reaches the so called critical value) and the universe enters a homogeneus and isotropic rapidly expanding. Some energy from photons becomes virtual quarks and hyperons, but these particles decay quickly. According to the ΛCDM model, dark energy is present as a property of space itself, beginning immediately following the period of inflation.
⇒ReheatingT ∼ 107 ÷104 GeV
The exponential de Sitter-like expansion that occurred during inflation ceases and the potential energy of the inflaton, the inflation field, decays into a hot, relativistic plasma of particles. The universe is dominated by radiation; quarks, electrons and neutrinos form.
⇒ Baryogenesis: Yes or No?
The magic words for a cosmologist of baryogenesis
Coleman –WeinbergPotential
FINITE TEMPERATURE EFFECTIVE POTENTIAL (FTEP): THE EVOLUTION OF THE MEXICAN-HAT FOR FINITE
TEMPERATURE PHASE TRANSITIONS
D E
Inflaton
CP Violation: 𝛈 problem
Standard Model CP Violation: A Great Disagreement
We need a correct amount of CP Violation
A link between B and CP
A Baryonic Asimmetry B tiny value for
the cosmological synthesis
Baryon Asymmetry
Parameter
CMB vs 𝛈 ratio
Dependence of the CMB Doppler peaks on 𝛈
Primordial Abundances
Nucleosynthesis versus η
Eta determines light nulei cosmic ratios
Via Electroweak Phase Transition - SM compatible Via Leptogenesis - sterile neutrinos GUT Processes - SU(5) Via Scalar Field (CPT Violation)
Baryogenesis (Riotto, Trodden)
Baryogenesis: Ingredients
Anomalous B-violating processes
Prevent washout by inverse processes
Sakharov Criteria
• B violation
• C & CP violation
• Nonequilibrium dynamics
Sakharov, 1967
We start from null baryonic number and baryon asimmetry: B = 0 and 𝛈 = 0
How can we create a B violation?
Anomalies: Standard Model borders
Baryonic
Leptonic
Chiral
It induces additional terms in the EW action and not conserved currents
The Anomaly is described by the Chern-Simons current
B+L Anomaly: the Sphaleron
Chern-Simons Number
Non Noether Baryonic and
Leptonic Currents
𝐵=∫𝑑3 𝑥 𝑗𝐵0 𝑁𝐶𝑆=
𝑛𝐹
32𝜋2𝑔2∫𝑑3 𝑥𝐾 0Baryonic
Number
Not conse
rved Ferm
ionic
Numbers and CS
Numbers
B + L not conservedB - L conserved
𝑁𝐶𝑆
Electroweak Sphaleronic Baryogenesis
This process trades three leptons, one from each generation, for nine quarks, three within each generation, and one of each color per generation. L and B are not conserved separately , though the quantum number B − L is.
With a 1° order Phase Transition, a FTEP and
a calibrated Higgs Mechanism, we can
trigger the B number violation process
Baryons via Leptogenesis: Sterile Neutrinos
A simple modification of the Standard Model that is able to realize the program of Sakharov is the one suggested by M. Fukugita and T.
Yanagida.
The Standard Model is extended by adding right-handed neutrinos, permitting implementation of the see-saw mechanism and
providing the neutrinos with mass. At the same time, the extended model is able to spontaneously generate leptons from the
decays of right-handed neutrinos.
Finally, the sphalerons are able to convert the spontaneously generated lepton asymmetry into the observed baryonic
asymmetry.
Sterile Neutrinos
If an asymmetry in the lepton number is produced, sphaleron transition, which conserve B - L, will reprocess it and convert it into baryon number.
GUT SO(10): Majorana Neutrinos
decay out-of-equilibrium
GUT Baryogenesis
SU(5): Leptoquark and X Bosons
Departure from Equilibrium: X
decay – it satisfies all Sakharov conditions
scalar
Scalar or Quintessential Baryogenesis
(De Felice, Nasri & MT; Li, Wang, Feng & Zhang)
If CPT simmetry is broken, 𝛈 asymmetry can be generated in equilibrium. We can’t break CPT explicitly but, if broken spontaneously, we can generate a baryon asymmetry. A single scalar field may be responsible for inflation, baryogenesis and dark energy.
Spontaneous Baryogenesis
(Cohen & Kaplan)
Bounds and Tests: Some Problems
EW: Only a small window of parameter space in extensions of the EW theory in which baryogenesis is viable; severe upper bound on lightest Higgs boson mass, mh < 120 GeV, stop mass close to experimental bound and < top quark mass (Light Higgs and Stop Scenario): truly disadvantaged by LHC measurements.
Lepto and GUT: Heavy Majorana neutrinos, more massive than the 10 TeV sphaleron, and superheavy bosons, with fine tuning.
Testability???Or maybe we simply
missed an antiuniverse…
New Physics: Strangelets
New Physics: Strangelets
10 years
From quark stars
A lot of new
unexpected stuff
Last but not least:Cosmic Rays Physics
Cosmic Rays AMS measures:
• |Z| independently in the Tracker, TOF and RICH subdetectors• Momentum in the tracking system.• Velocity independently by the TOF, TRD and RICH subdetectors.
CR PropagationCR Propagation Models with DM: Steady-state Parker Equation with a primary flux source term
DM Flux Source
Propagation Parameters From B/C and Be Isotopes
Measures
Number density
Diffusion coefficient Convective Galactic Wind Annihilation Rate
CR Propagation Constraint
Light nuclei ratios to fix the propagation parameters and improve the accuracy of
GALPROP and DRAGON software
Average residence time in the Galaxy
Average grammage (traversed matter)