[Paper Review] New symmetries in microphysics, new stable forms of matter around us

Maxim Khlopov|arXiv (Cornell University)|Jul 4, 2006

Dark Matter and Cosmic Phenomena16 citations

TL;DR

This paper proposes that new symmetries in microphysics could lead to stable, charged heavy leptons and quarks forming composite dark matter, hidden in elusive atoms. It identifies primordial helium as a key trap for negatively charged heavy particles, and argues that cosmic ray and accelerator searches for these particles provide crucial tests for such models.

ABSTRACT

Extension of particle symmetry implies new conserved charges and the lightest particles, possessing such charges, should be stable. Created in early Universe, stable charged heavy leptons and quarks can exist and, hidden in elusive atoms bound by Coulomb attraction, can play the role of dark matter. The problem of this scenario is that in the expanding Universe it is not possible to recombine all the charged particles into elusive "atoms", and positively charged particles, which escape such recombination, bind with electrons in atoms of anomalous isotopes with pregalactic abundance, generally exceeding terrestrial upper limits. Realistic scenarios of composite dark matter, avoiding this problem of anomalous isotope over-production, inevitably predict the existence of primordial "atoms", in which primordial helium traps all the free negatively charged heavy constituents with charge -2. Study of the possibility for such primordial heavy alpha-particle with compensated charge to exist as well as the search for the stable charged constituents in cosmic rays and accelerators provide crucial test for the new forms of stable matter.

Motivation & Objective

• To investigate the cosmological viability of composite dark matter models involving stable, charged heavy particles beyond the Standard Model.
• To resolve the problem of anomalous isotope overproduction in scenarios with stable charged constituents by identifying mechanisms that suppress such overproduction.
• To propose that primordial helium can trap negatively charged heavy particles, forming stable, neutral 'heavy atoms' that evade detection but could be tested via cosmic rays.
• To identify observable signatures—such as free anutium or A^{--} particles—in cosmic rays resulting from the destruction of these heavy atoms.
• To provide a critical test for such models through accelerator experiments like ATLAS at the LHC.

Proposed method

• Extends the Standard Model via new gauge symmetries (e.g., SU(3)c × SU(2) × SU(2)′ × U(1)) to introduce stable charged heavy fermions, such as tera-quarks and tera-leptons.
• Applies conservation of a new charge F = (B−L) − (B′−L′) to ensure stability of heavy particles and prevent mixing with light fermions.
• Models the formation of bound states—like (UUUEE) 'tera-helium' atoms or AC-atoms—via Coulomb-like interactions between heavy charged constituents.
• Analyzes primordial nucleosynthesis and recombination dynamics to assess the abundance of anomalous isotopes, particularly in charge-asymmetric scenarios.
• Evaluates the survival and detectability of these heavy atoms in the interstellar medium, focusing on their destruction by galactic cosmic rays.
• Estimates the flux of free charged components (e.g., [anutium−N̄] or A^{--}) in cosmic rays, using models of cosmic ray spallation on heavy atoms.

Experimental results

Research questions

• RQ1 Can stable, charged heavy particles from extended symmetries form long-lived composite dark matter without overproducing anomalous isotopes?
• RQ2 What role does primordial helium play in stabilizing and hiding negatively charged heavy constituents in the early Universe?
• RQ3 How can cosmic ray interactions reveal the presence of hidden, stable charged particles through the production of free anutium or A^{--} components?
• RQ4 What constraints do observed isotope abundances and cosmic ray data impose on models of composite dark matter with charged constituents?
• RQ5 Can accelerator experiments like ATLAS at the LHC detect the charged components of such composite dark matter?

Key findings

• In charge-asymmetric models, the pregalactic abundance of C^{++} exceeds terrestrial limits by ten orders of magnitude, necessitating suppression mechanisms tied to the existence of new conserved charges.
• In scenarios with excess anti-U quarks, the primordial abundance of positively charged U-baryons is exponentially suppressed, avoiding anomalous isotope overproduction.
• Anutium (bound by excess anti-U quarks and anti-neutrons) forms and binds with 4He to create neutral ANO-helium, which can survive in the interstellar medium.
• Galactic cosmic rays can destroy ANO-helium, releasing free [anutium−N̄] components with a flux up to ∼10^{-7} relative to 4He, detectable by PAMELA and AMS experiments.
• The flux of free A^{--} particles from OLe-helium destruction is estimated at ∼10^{-9} relative to 4He, still potentially accessible to current and future space-based detectors.
• Accelerator searches for stable quarks and leptons at the LHC, particularly in ATLAS, are identified as critical tests for the existence of charged constituents in composite dark matter.