Stability of neutrino mass degeneracy

Ma, Ernest

doi:10.1088/0954-3899/25/10/102

Cited by 35 publications

(20 citation statements)

References 35 publications

(11 reference statements)

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“…[14][15][16]. When two heavy ions at 35 MeV/nucleon collide, the excitation energy deposited in the system is large enough for the system to get gently compressed at the beginning and then it expands and enters an instability region, the spinodal region, similar to the liquid-gas (LG) phase transition [17][18][19][20][21]. Fig.…”

Section: Methodsmentioning

confidence: 99%

Triple α -particle resonances in the decay of hot nuclear systems *

Zhang¹,

Wang²,

Bonasera³

et al. 2019

Chinese Phys. C

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The Efimov (Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64) Zn( 64 Ni) + 70(64) Zn( 64 Ni) reactions at beam energy of E/A=35 MeV/nucleon. In heavy ion collisions, the αs interact with each other and can form complex systems such as 8 Be and 12 C. For the 3α systems, multi resonance processes give rise to excited levels of 12 C. The interaction between any two of the 3α particles provides events with one, two or three 8 Be. Their interfering levels are clearly seen in the minimum relative energy distributions. Events of three couple α relative energies consistent with the ground state of 8 Be are observed with the decrease of the instrumental error at the reconstructed 7.458 MeV excitation energy of 12 C, which was suggested as the Efimov (Thomas) state.

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Section: Methodsmentioning

confidence: 99%

Triple α -particle resonances in the decay of hot nuclear systems *

Zhang¹,

Wang²,

Bonasera³

et al. 2019

Chinese Phys. C

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“…According to C.W Ma and Y.G. Ma [74] the difference between qth order Renyi entropy and 1 st order Renyi entropy is found just to be a q dependent constant but which is very sensitive to the form of probability distribution. Renyi entropy can play a potential role to investigate the fractal characteristics of multiparticle production process [75][76].…”

Section: Entropy and Fractalitymentioning

confidence: 99%

Multifractal Analysis of Charged Particle Multiplicity Distribution in the Framework of Renyi Entropy

Bhattacharyya

Neagu

Firu

2018

Advances in High Energy Physics

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A study of multifractality and multifractal specific heat has been carried out for the produced shower particles in nuclear emulsion detector for 16 O-AgBr, 28 Si-AgBr, and 32 S-AgBr interactions at 4.5AGeV/c in the framework of Renyi entropy. Experimental results have been compared with the prediction of Ultra-Relativistic Quantum Molecular Dynamics (UrQMD) model. Our analysis reveals the presence of multifractality in the multiparticle production process in high energy nucleus-nucleus interactions. Degree of multifractality is found to be higher for the experimental data and it increases with the increase of projectile mass. The investigation of quark-hadron phase transition in the multiparticle production in 16 O-AgBr, 28 Si-AgBr, and 32 S-AgBr interactions at 4.5 AGeV/c in the framework of Ginzburg-Landau theory from the concept of multifractality has also been presented. Evidence of constant multifractal specific heat has been obtained for both experimental and UrQMD simulated data.

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“…If the hierarchy is inverted [5][6][7][8][9][10] one instead finds m 3 ∼ 0, m 2 ∼ δm atmospheric , and m 1 ∼ δm atmospheric . However, it is also possible that neutrino masses are degenerate [11][12][13][14][15][16][17][18][19][20][21], m 1 ∼ m 2 ∼ m 3 ≫ δm atmospheric , in which case oscillation experiments are not useful for determining the absolute mass scale.…”

Section: Neutrino Massesmentioning

confidence: 99%

“…If the hierarchy is inverted [5-10] one instead finds m 3 ∼ 0, m 2 ∼ δm atmospheric , and m 1 ∼ δm atmospheric . However, it is also possible that neutrino masses are degenerate [11][12][13][14][15][16][17][18][19][20][21], m 1 ∼ m 2 ∼ m 3 ≫ δm atmospheric , in which case oscillation experiments are not useful for determining the absolute mass scale.Experiments which rely on kinematical effects of the neutrino mass offer the strongest probe of this overall mass scale. Tritium decay measurements have been able to put an upper limit on the electron neutrino mass of 2.2 eV (95% conf.)…”

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confidence: 99%

Neutrino physics from cosmological observations

Hannestad¹

2003

Nuclear Physics B - Proceedings Supplements

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We review the current status of neutrino cosmology, focusing mainly on the question of the absolute values of neutrino masses and the possibility of a cosmological neutrino lepton asymmetry. Neutrino massesThe absolute value of neutrino masses are very difficult to measure experimentally. On the other hand, mass differences between neutrino mass eigenstates, (m 1 , m 2 , m 3 ), can be measured in neutrino oscillation experiments. Observations of atmospheric neutrinos suggest a squared mass difference of δm 2 ≃ 3 × 10 −3 eV 2 [1,2]. While there are still several viable solutions to the solar neutrino problem the so-called large mixing angle solution gives by far the best fit with δm 2 ≃ 5×10 −5 eV 2 [3,4] (see also contributions by A. Hallin and A. Smirnov in the present volume).In the simplest case where neutrino masses are hierarchical these results suggest that m 1 ∼ 0, m 2 ∼ δm solar , and m 3 ∼ δm atmospheric . If the hierarchy is inverted [5-10] one instead finds m 3 ∼ 0, m 2 ∼ δm atmospheric , and m 1 ∼ δm atmospheric . However, it is also possible that neutrino masses are degenerate [11][12][13][14][15][16][17][18][19][20][21], m 1 ∼ m 2 ∼ m 3 ≫ δm atmospheric , in which case oscillation experiments are not useful for determining the absolute mass scale.Experiments which rely on kinematical effects of the neutrino mass offer the strongest probe of this overall mass scale. Tritium decay measurements have been able to put an upper limit on the electron neutrino mass of 2.2 eV (95% conf.) [22] (see also the contribution by Ch. Weinheimer in the present volume). However, cosmology at present yields an even stronger limit which is also based on the kinematics of neutrino mass.Neutrinos decouple at a temperature of 1-2 MeV in the early universe, shortly before electron-positron annihilation. Therefore their temperature is lower than the photon temperature by a factor (4/11) 1/3 . This again means that the total neutrino number density is related to the photon number density by n ν = 9 11 n γ (1)Massive neutrinos with masses m ≫ T 0 ∼ 2.4 × 10 −4 eV are non-relativistic at present and therefore contribute to the cosmological matter density [23][24][25]]calculated for a present day photon temperature T 0 = 2.728K. Here, m ν = m 1 + m 2 + m 3 . However, because they are so light these neutrinos free stream on a scale of roughly k ≃ 0.03m eV Ω 1/2 m h Mpc −1 [26][27][28]. Below this scale neutrino perturbations are completely erased and therefore the matter power spectrum is suppressed, roughly by ∆P/P ∼ −8Ω ν /Ω m [28].This power spectrum suppression allows for a determination of the neutrino mass from measurements of the matter power spectrum on large scales. This matter spectrum is related to the galaxy correlation spectrum measured in large scale structure (LSS) surveys via the bias parameter, b 2 ≡ P g (k)/P m (k). Such analyses have been performed several times before [29,30], most recently using data from the 2dF galaxy survey [31]. This investigation finds an upper limit of 1.8-2.2 eV for the sum of neutrin...

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Stability of neutrino mass degeneracy

Abstract: Two neutrinos of Majorana masses m 1,2 with mixing angle θ are unstable against radiative corrections in the limit m 1 = m 2 , but are stable for m 1 = −m 2 (i.e. opposite CP eigenstates) with θ = 45 • which corresponds to an additional symmetry.

Cited by 35 publications

References 35 publications

Triple α -particle resonances in the decay of hot nuclear systems *

Triple α -particle resonances in the decay of hot nuclear systems *

Multifractal Analysis of Charged Particle Multiplicity Distribution in the Framework of Renyi Entropy

Neutrino physics from cosmological observations

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