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)