New physics, the cosmic ray spectrum knee, and pp cross section measurements

We explore the possibility that a new-physics interaction can provide an explanation for the knee just above 10⁶ GeV in the cosmic ray spectrum. We model the new-physics modifications to the total proton–proton cross section with an incoherent term that allows for missing energy above the scale of new physics. We add the constraint that the new physics must also be consistent with published pp cross section measurements, using cosmic ray observations, an order of magnitude and more above the knee. We find that the rise in cross section required at energies above the knee is radical. The increase in cross section suggests that it may be more appropriate to treat the scattering process in the black disc limit at such high energies. In this case there may be no clean separation between the standard model and new-physics contributions to the total cross section. We model the missing energy in this limit and find a good fit to the Tibet III cosmic ray flux data. We comment on testing the new-physics proposal for the cosmic ray knee at the Large Hadron Collider.     

Type II seesaw and the PAMELA/ATIC signals

We discuss how the cosmic ray signals reported by the PAMELA and ATIC/PPB-BETS experiments may be understood in a Standard Model (SM) framework supplemented by type II seesaw and a stable SM singlet scalar boson as dark matter. A particle physics explanation of the ‘boost’ factor can be provided by including an additional SM singlet scalar field.     

Puzzles in astrophysics in the past and present

About 400 years have passed since the great discoveries by Galileo, Kepler, and Newton, but astronomy still remains an important source of discoveries in physics. They start with puzzles, with phenomena difficult to explain, and phenomena which in fact need new physics for explanation. Do such puzzles exist now? There are at least three candidates: absence of absorption of TeV gamma radiation in extragalactic space (violation of Lorentz invariance?), absence of GZK cutoff in the spectrum of ultrahigh-energy cosmic rays (new particle physics?), tremendous energy (up to 10⁵⁴ erg) released in gamma ray bursts on a time scale of a second (collapsing stars or sources of a new type?). Do these puzzles really exist? A critical review of these phenomena is given.     

Synchronisation of chaos and its applications

Dynamical networks are important models for the behaviour of complex systems, modelling physical, biological and societal systems, including the brain, food webs, epidemic disease in populations, power grids and many other. Such dynamical networks can exhibit behaviour in which deterministic chaos, exhibiting unpredictability and disorder, coexists with synchronisation, a classical paradigm of order. We survey the main theory behind complete, generalised and phase synchronisation phenomena in simple as well as complex networks and discuss applications to secure communications, parameter estimation and the anticipation of chaos.     

The Spread of Ideas in a Network—The Garbage-Can Model

The main goal of our work is to show how ideas change in social networks. Our analysis is based on three concepts: (i) temporal networks, (ii) the Axelrod model of culture dissemination, (iii) the garbage can model of organizational choice. The use of the concept of temporal networks allows us to show the dynamics of ideas spreading processes in networks, thanks to the analysis of contacts between agents in networks. The Axelrod culture dissemination model allows us to use the importance of cooperative behavior for the dynamics of ideas disseminated in networks. In the third model decisions on solutions of problems are made as an outcome of sequences of pseudorandom numbers. The origin of this model is the Herbert Simon’s view on bounded rationality. In the Axelrod model, ideas are conveyed by strings of symbols. The outcome of the model should be the diversity of evolving ideas as dependent on the chain length, on the number of possible values of symbols and on the threshold value of Hamming distance which enables the combination.     

Effect of Savings on a Gas-Like Model Economy with Credit and Debt

In kinetic exchange models, agents make transactions based on well-established microscopic rules that give rise to macroscopic variables in analogy to statistical physics. These models have been applied to study processes such as income and wealth distribution, economic inequality sources, economic growth, etc., recovering well-known concepts in the economic literature. In this work, we apply ensemble formalism to a geometric agents model to study the effect of saving propensity in a system with money, credit, and debt. We calculate the partition function to obtain the total money of the system, with which we give an interpretation of the economic temperature in terms of the different payment methods available to the agents. We observe an interplay between the fraction of money that agents can save and their maximum debt. The system’s entropy increases as a function of the saved proportion, and increases even more when there is debt.     

Ultra high energy cosmic rays above 1011 GeV: Hints to new physics beyond Standard Model

The observed cosmic ray events above 10¹² GeV are difficult to explain within the context of known physics of propagation of known particles in the Universe and within the standard acceleration mechanisms that are likely to operate in powerful astrophysical objects. Several ideas of possible new physics beyond the Standard Model have been suggested in order to explain these events. The major suggestions are summarized here.     

Heavy ions with the Large Hadron Collider and the ALICE detector

The Large Hadron Collider (LHC) under construction at CERN is also planned as a heavy ion collider with lead ions colliding at an energy of 2.7+2.7 ATeV. This corresponds to collisions of matter with cosmic rays of the utmost energies observed so far promising the study of new and exciting aspects of physics. Minor improvements of the newly commissioned lead ion source at the CERN SPS are necessary in order to provide a luminosity of L=2×10²⁷ cm^?2s^?1. The detector ALICE has been chosen as the third detector for the LHC and will be dedicated to the physics of these nuclear collisions and also to the large cross section physics in p+p collisions.     

Artem Isaak Alikhanian (1908–1978) (Biographic Sketch)

A.I. Alikhanian is one of founders of experimental nuclear physics in USSR. Starting and development of the atomic nuclei, cosmic ray, and elementary particle physics in Armenia relates to the name Alikhanian. He created the Aragats and Nor-Amberd high-altitude cosmic stations and the Yerevan Physics Institute. He made an essential contribution into the development of high-energy physics and played a significant role in creation of methods of recording high-energy particles.     

Four decades of nuclear tracks research in India

The science of solid state nuclear track detectors (SSNTDs)—“Trackology”—developed by R.L. Fleischer, P.B. Price and R.M. Walker in the early 1960s of the last century is an interesting and potentially useful concept with something to offer to almost all branches of science and technology. In fact nuclear tracks find applications wherever solid state damage occurs. Apart from the direct applications of far reaching consequences in nuclear physics, other areas as diverse as bio-medical sciences, cosmic rays and space physics, environmental research, geological sciences, material science, microanalysis, mine safety, nuclear technology, uranium prospecting, etc. have been greatly influenced by SSNTDs.

In this presentation, we attempt to provide an overview of the growth of nuclear tracks research in India over the last four decades and the contributions of various groups from Universities, Institutes, Nuclear Track Society of India and the Department of Atomic Energy in nurturing nuclear track research in the country. Finally, a summary of the significant contributions made by Indian scientists is also presented in this paper along with the overall impact it has made at the national and international level in many areas of basic and applied sciences such as cosmic rays and space physics, fusion–fission and particle evaporation, heavy ion ranges and energy-loss measurements, country-wide indoor radon–thoron survey, geochronology, environmental sciences, track-etch membranes and ion tracks technology, material science, physics and chemistry of fission, etc.     

From extensive air showers to the characteristics of primary cosmic rays. To the 120th Anniversary of the Birth of D. V. Skobel’tsyn

The works by D.V. Skobel’tsyn that laid the foundation of the contemporary physics of cosmic rays and the physics of high energies are considered. Skobel’tsyn demonstrated that cosmic rays contain particles whose energy substantially surpasses the energies that are typical of radioactive decay, discovered the existence of air showers, i.e., when several particles hit an array simultaneously, and performed a series of investigations into extensive air showers that resulted in the discovery of a nuclear-cascade process in the atmosphere. The results that Skobel’tsyn obtained were of primary importance for the further development of cosmic-ray physics.     

Neutrino—nucleon cross-section at ultra-high energies in models with large extra dimensions

We examine whether the models with large extra dimensions can provide an explanation for the GZK violating ultra-high energy cosmic rays (UHECR). In these models the neutrino—nucleon cross-section rises rapidly with energy and hence cosmic rays might be identified with neutrinos. We calculate the neutrino-nucleon cross-section at ultra high energies by assuming that it is dominated by the production ofp-branes. We perform the calculation in a generalized Randall-Sundrum model and Lykken-Randall model and find cross-sections of the order of 100 mb at neutrino energies of 10²⁰ eV, which is required for explaining UHECR events.     

The imprint of inflation on the cosmic microwave background

The cosmic microwave background is the most precise and the most simple cosmological dataset. This makes it our most prominent window to the physics of the very early Universe. In this article I give an introduction to the physics of the cosmic microwave background and show in some detail how primordial fluctuations from inflation are imprinted in the temperature anisotropy and polarisation spectrum of the CMB. I discuss the main signatures that are suggesting an inflationary phase for the generation of initial fluctuations.     

Precision cosmology and the density of baryons in the universe

Big-bang nucleosynthesis (BBN) and cosmic microwave background (CMB) anisotropy measurements give independent, accurate measurements of the baryon density and can test the framework of the standard cosmology. Early CMB data are consistent with the long-standing conclusion from BBN that baryons constitute a small fraction of matter in the Universe, but may indicate a slightly higher value for the baryon density. We clarify precisely what the two methods determine and point out that differing values for the baryon density can indicate either an inconsistency or physics beyond the standard models of cosmology and particle physics. We discuss other signatures of the new physics in CMB anisotropy.     

M theory and singularities of exceptional holonomy manifolds

M theory compactifications on G₂ holonomy manifolds, whilst supersymmetric, require singularities in order to obtain non-Abelian gauge groups, chiral fermions and other properties necessary for a realistic model of particle physics. We review recent progress in understanding the physics of such singularities. Our main aim is to describe the techniques which have been used to develop our understanding of M theory physics near these singularities. In parallel, we also describe similar sorts of singularities in Spin(7) holonomy manifolds which correspond to the properties of three dimensional field theories. As an application, we review how various aspects of strongly coupled gauge theories, such as confinement, mass gap and non-perturbative phase transitions may be given a simple explanation in M theory.     

Self-interaction in the von Kármán cosmic string street configuration

We study the problem of electromagnetic self-interaction of line sources in the presence of an array of parallel cosmic strings akin to the von Kármán vortex street configuration. Keeping in mind possible applications in condensed matter physics we consider also a mixed array where both deficit angle and excess angle cosmic strings appear. We obtain explicit expressions for both the electric and magnetic self-energies for the cases studied and demonstrate that these results reproduce the known self-energies in the single-string limit.     

PLASTIC SCINTILLATOR RESPONSE TO CHARGED PARTICLES

Plastic scintillators with many advantages are widely used in particle physics. Researches on plastic scintillator response at both high energy and high electric charge are significant to the experiments in high energy physics and cosmic ray physics. In addition to many important astrophysical results, the high energy cosmic rays experiments at the University of Chicago accumulate data for plastic scintillator response to relativistic particles of high electric charges. This paper introduces the cosmic ray experiments mentioned above, presents data analysis results and the discusses the nonlinear response of plastic scintillators.     

D-term inflation, cosmic strings, and consistency with cosmic microwave background measurements

Standard D-term inflation is studied in the framework of supergravity. D-term inflation produces cosmic strings; however, it can still be compatible with cosmic microwave background (CMB) measurements without invoking any new physics. The cosmic strings contribution to the CMB data is not constant, nor dominant, contrary to some previous results. Using current CMB measurements, the free parameters (gauge and superpotential couplings, as well as the Fayet-Iliopoulos term) of D-term inflation are constrained.     

Statistical methods in nonlinear dynamics

Sensitivity to initial conditions in nonlinear dynamical systems leads to exponential divergence of trajectories that are initially arbitrarily close, and hence to unpredictability. Statistical methods have been found to be helpful in extracting useful information about such systems. In this paper, we review briefly some statistical methods employed in the study of deterministic and stochastic dynamical systems. These include power spectral analysis and aliasing, extreme value statistics and order statistics, recurrence time statistics, the characterization of intermittency in the Sinai disorder problem, random walk analysis of diffusion in the chaotic pendulum, and long-range correlations in stochastic sequences of symbols.     

宇宙线对地球气候的影响

对宇宙线影响地球气候的一些观测结果和物理机制的研究进行了总结和概述,主要讨论了宇宙线对大气中化学反应、云形成过程等的影响,并给出了羊八井宇宙线观测站对宇宙线流强和大气参量日变化的初步观测结果．