Transcript tachyon - George Mason University
The hunt for the tachyon: Six Observations consistent with the electron neutrino being a m 2 = -- 0.11 + 0.02 eV 2 tachyon Robert Ehrlich George Mason University mason.gmu.edu/~rehrlich
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Click on image to show video: “Einstein on faster-than-light speeds?”
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v> c is verboten
Unless…
No information sent In a warped space-time Expansion of space itself No infinite energy needed?
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E Why were tachyons first proposed? (1962)
E
mc
2 1
v
2 /
c
2
E
mc
2 1
v
2 /
c
2
dv dE
0
a 2-way barrier
v
c m
2 0
m is imaginary!
dv dE
0
speed, v/c
Bilaniuk, O.-M. P.; Deshpande, V. K.; Sudarshan, E. C. G. "'Meta' Relativity". American Journal of Physics 30 718 (1962).
Neutrinos: the only candidates
Best tritium beta decay data (as of 2015)
m
2 1 .
1 2 .
4
eV
2 KATRIN experiment 5-sigma “discovery potential”
m
0 .
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eV m
2 ~ 0 .
1
eV
2 (?) For such a mass no speed measurement could reveal any departure from c (any feasible L & E gives immeasurably small dt) 2:22 AM 4
How I became a “tachyon hunter?”
Chodos et al. (1985, 1992): Neutrinos as tachyons
Their prediction: Energetically forbidden processes like proton beta decay become allowed at high enough energies if the electron neutrino is a tachyon – the threshold depends on the mass of v e 2:22 AM Basic idea: Only tachyons can have in different reference frames 5
e p n
v
Lab frame: proton beta decay
distance
e p n Only tachyons can have:
v
In rest frame Looks like:
distance
High energy cosmic rays
Primary cosmic rays create showers of secondary particles 2:22 AM 8
2:22 AM The cause of the knee?
An unconventional proposal: “lost” protons for E > E
knee
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“Missing protons” interpreted as being due to the onset of proton beta decay for E > E knee Two 1999 articles 1,2 applying this idea: (1) E knee
implies specific tachyonic mass value for neutrino:
(2) Corroboration: P decay above knee leads to “pile-up” of neutrons just above knee or a small peak at ~ 4.5 PeV. Neutrons unlike protons travel in straight lines & might reach us from sources normally considered to distant, because of a “decay chain” 1. Ehrlich, R., Physical Review D, 60, 17302 (1999 2. Ehrlich, R., Physical Review D, 60, 73005 (1999) CR’s would point back to source if most of time they are neutrons!
Where to see small 4.5 PeV neutron peak?
Cygnus X-3 is an X-ray binary with a 4.79 h period One of the most intrinsically luminous sources in the galaxy Numerous reports of PeV cosmic rays in the 1970’s & 80’s, especially when making a 4.79 h phase cut Only one experiment had enough events for E > 1 PeV to make an energy histogram
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2 nd 1999 paper in which 4.5 PeV peak claimed for Cygnus X-3 Counts above background vs energy Well-known background shape: Signal based on counts in 2.5% wide interval of phase, background based on the other 97.5%
50% 2:22 AM 1 PeV
5 PeV
10 PeV 100 PeV Possible reason why other high statistics
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Part II: The 6 values of
average eV
Cosmological data Cosmic ray data Nuclear experiment
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“Fine structure” in CR spectrum above knee (recall earlier 4.5 PeV peak) 4.5 PeV 75% 2:22 AM 2013 paper from Tunka Collaboration (dE/E ~ 15%) Excess counts after subtracting two straight lines shown 14
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2
nd
Knee in CR spectrum
Interpret 2 nd knee as threshold for alpha decay (supported by sudden lowering of average atomic weight found at that energy) 1st 2nd 15 2:22 AM
The Cosmic Background Radiation (CMB)
Whole sky image of CMB after filtering
A measure of the temperature of space
-- A remnant of the big bang (universe 2% its present age) -- Fluctuations only ~ 1 part in 100,000) -- CMB = the primordial “seeds” for future matter clumping Large scale Small scale Multipole expansion to fit the data
17 free parameters in the fit! 3 of them involve neutrinos
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Radiation energy density during early universe
photons neutrinos
is the effective number of neutrinos at the time of CMB decoupling
-- need not be an integer -- it controls the rate of expansion & affects the CMB “wiggles” -- standard model value = 3.0
1 (other values “new physics”) 1 Actually, 3.046 – 0.046 correction due to decoupling 2:22 AM 17
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Calculation based on
(Davies & Moss, 2012) Departure from standard model value DM use: Tachyonic neutrino mass A more up-to-date value: Nollett & Steigman (2014) Gives an actual value & not an upper limit: 2:22 AM 18
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Fit to CMB & other data (Battye & Moss, 2014) 2:22 AM BM conclude that the 3 flavor masses have nearly same mass: Otherwise no agreement with tiny dm 2 seen in oscillation data: biggest is 19
An alternate view of BM fit to sum of 3 neutrino masses
Suppose electron neutrino is a tachyon with negative energy. Energy density of a sea of tachyons: Gravitational mass negative for a tachyon since number density cannot be Why Let the magnitudes of the 3 masses be equal
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5 Chodos: Neutrinos must come in: + m 2 pairs
Flavor states Fixes big problem with previous one: inconsistency with + m
2 0
4 th Sterile flavor state
- m
Based on BM fit to CMB fluctuations when a sterile neutrino is included its mass is found To be: 0.450 + 0.124 eV. Thus, with the right pairing we have:
2
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Neutrinoless Double Beta Decay
(A,Z) (A,Z-2) +2e
--
Result contested by other negative experiments 2:22 AM Monochromatic!
KE of 2 electrons Other issues: 22
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The six values of
average eV B & C are 2 interpretations of same CMB data Average if it is dropped This experiment may be wrong + other issues
No known observations in conflict with the claim
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Three tests of claim that
(1) Next galactic supernova (~1-2 SN’s per century) (2) Clear evidence for an E = 4.5 PeV cosmic ray peak (3) A highly precise tritium beta decay experiment 2:22 AM 24
Suppose SN emits +m 2 neutrinos with various energies 1/E 2
t
1/E 2
t
m
2
t o
2
E
2 arrival time relative to light & t 0 is light travel time from SN - m 2 Leads light +m 2 Lags light
SN models predict ms-fine structure
Core-collapse model predictions Unless neutrino mass very tiny the energy-dependent travel times from source will “wash out” any ms-fine structures in observed neutrinos at detector Suppose ms-fine structure is seen must have |m| < 0.02 eV claim is false 2:22 AM If not seen Find neutrino that best “unsmears” data. Subtracting from the measured arrival time the neutrino travel time with m a fitted parameter :
t
m
2
t o
2
E
2 26
2
nd
test: Find 4.5 PeV CR neutron peak
Earlier negative experiments may have not seen a signal because they lacked data in the knee region and failed to make the proper cuts
Cygnus X-3
Main cut needed is on the phase: (a) Need a very accurate ephemeris to find the phase: Example: need to have time varying period accurate to 0.00007% for 10 y of data to see a sharp phase peak (b) Look at data sample covering 1 to 10 PeV to find a peak in phase histogram (c) Also, deep underground muons Based on a citation search no proper test of 1999 claim of a 4.5 PeV peak from Cygnus X-3 has ever been made! Test could be done using existing data
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My message to KATRIN: Messen Sie die Neutrinomasse ohne Fehler, und finden Sie den ehrlichen Wert!
2:22 AM Measure the neutrino mass without error and find the honest value.
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A bit of philosophy
on two different approaches to particle physics
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Two types of particle physicists
Pack hunters (6,000 Higgsians) Lone wolves or crackpots
Massive $10 Billion apparatus & many years spent in preparation Analyze existing data in a novel way & takes little time to complete Problems: getting funding & you won’t get the Nobel prize Advantage of getting advice from many highly knowledgeable experts Problems: getting access to someone else’s raw data & most of the time you will be wrong Advantage of not getting advice from many experts Lone wolves may be … far more dangerous than the average wolf that is a member of a pack. However, lone wolves have difficulty hunting, as wolves’ favorite prey, … and will generally hunt smaller animals and scavenge carrion.
Wikipedia entry