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Overview of Exotic Strange Quark Matter Search Experiments. James Nagle. Symposium on Fundamental Issues in Elementary Matter 25-29 September 2000 Physikzentrum Bad Honef. q. q. q. q. q. q. q. q. q. q. q. q. q. q. q. q. q. q. What is Quark Matter?. - PowerPoint PPT Presentation
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Overview of Exotic Strange Quark Matter
Search Experiments
Symposium on Fundamental Issues inElementary Matter25-29 September 2000Physikzentrum Bad Honef
James Nagle
What is Quark Matter?
q q qq
q
q
q
q
q
q
q
q
q= qq
qqq
q
qqq
q
q
q
q
q
QCD allows for bound states of quarks in color-singlet configurations
Nuclei are not single hadrons, but bound states of individual nucleons
Quark matter composed of up and down quarks for (A>1) is knownto be unstable, otherwise normal nuclei would decay into such quark matter.
What is Strange Quark Matter?Strange quark matter composed of up, down and strange quarks may be meta-stable or even stable in bulk.
States have a reduced Fermi energy, reduced Coulomb, no fission.Thus SQM states could range in size from A=2 to A > 106.
Witten proposed SQM could even be the ground state of nuclear matter and could exist in bulk as remnants of the Big Bang.
u du d s
Ener
gy L
evel
Strange Quark Mass
Quark Matter Strange Quark Matter
Where to findStrange Quark Matter?
1. Remnants from the early universe
2. Core of dense stars
3. Created by coalescence of multiple strange baryons
4. Created via a quark-gluon plasma formed in relativistic heavy ion collisions
1. Remnants of the Big Bang
SQM left over from the Big Bang could be seen in cosmic rays and may have a 10-7 concentration by mass in the Earth’s crust.
Many searches with null results.
Cosmological and Astrophysical SQM
2. Core of Dense Stars
Neutron stars may have quark matter core which could be SQM
E. Witten, Phys. Rev. D 30, 272 (1984).A. DeRujula and S.L. Glashow, Nature 312, 20 (1984).J.D. Bjorken and L.D. McLerran, Phys. Rev. D 20, 2353 (1979).
N. Glendenning and J. Scahffer-Bielich, Phys. Rev. C 58, 1298 (1998).
3. Coalescence of SQM
n
nn p
p
A. Baltz, C. Dover et al., Phys. Lett. B, 325, 7 (1994).
In p + p, p + A, A + A collisions, at freeze-out baryons and strange baryons can coalesce to form nuclei and hypernuclei.
If strange quark matter states are more stable than these hypernuclei, then the state can make a transition to form SQM.
q
q
q
qqq
q
qqq
q
q
q
q
q
J. Schaffner et al., J. Phys. G 23, 2107 (1997)., S.A. Chin and A. Kerman, Phys. Rev. Lett. 43, 1292 (1979).H. Liu and G.L. Shaw, Phys. Rev. D 30, 1137 (1984), C.Greiner et al. Phys. Rev. Lett. 58 (1987) 1825.C.Greiner and H. Stocker, Phys. Rev. D 44 (1991) 3517.
Cools by hadron emissionat the surface
p
)( suK
Preferential emission of anti-strange quarks
Once cooled down, remaining quarks form a meta-stable state of SQM with:
(A= 2-100 and |S|=1-100).
4. Quark-Gluon Plasma
H-dibaryonThe H-dibaryon is a six-quark color singlet hadron.
It would be the lightest strange quark matter state, and there is no theoretical consensus about its mass.
p-
p , 0n
n
nn Very deeply bound, only S=2 decay, long lifetime > 105 seconds
Unbound, possibly a resonance similar to d* in proton-proton interactions
Very loosely bound, unclear distinction between H and bound state- possibly very short lifetime ~ 1/2
Bound H state, with lifetime ~ 10-8 seconds >
d
dsu
u s
“For all H masses except those near the threshold, we expect a true six-quark bound state.”Donoghue et al., Phys. Rev. D 34, 3434 (1986).
H Mass Threshold
What do we know about the H?
1. Carroll et al., Phys. Rev. Lett. 41, 777 (1978). p + p K K H2. Gustafson et al., Phys. Rev. Lett. 37, 474 (1976). p + A H X3. Shahbazian et al., Z. Phys. C39, 151 (1988). p + A HX 4. Alekseev et al., Yad. Fiz. 52, 1612 (1990). n + A HX5. Bawolff et al., Ann. Physik Leipzig 43, 407 (1986). + A HX6. Condo et al., Phys. Lett. 144B, 27 (1984). p + A HX ………….
A. E836 BNL-AGS E224 KEK
B. E888 BNL-AGS KTeV FNAL E910 BNL-AGS
C. E810 BNL-AGS E896 BNL-AGS
K- + 3He K+ + ( + p) + n K+ + + n
p + A ( + ) + X H + X
A + A ( + ) + X H + X
Best Limits to Date
“To conclude, in the context of published models, our [KTeV] result …. in conjunction with the result from experiment E888, rules out the [H dibaryon] model proposed by Donoghue et al. for all S=1 transitions.”
A. Alavi-Harati et al., Phys. Rev. Lett. 84, 2593 (2000).
pnn
E888KTeVE224E836
Plot from Ram Ben-David and D. Ashery
Let’s look in more detail….
Experiment 888Originally E888 had two possible H candidates, but further studies support the conclusion that they are consistent with known backgrounds.
Sensitive to: H n and H 0 n
< 60 nbE888 sensitivity
~ 1.0 bmodel prediction
J. Belz et al., Phys. Rev. Lett. 76, 3277 (1996).J. Belz et al., Phys. Rev. C 56, 1164 (1997).Cousins et al., Phys. Rev. D 56, 1673 (1997)
Experiment 888: Part IIE888 limit of H < 60 nb assumed H production peaked at midrapidity (like p+p).
Using transport model RQMDv2.3 shows an H distribution shifted towards target rapidity as suggested by Cole et al. This reduces the acceptance substantially and yields a limit of H < 1.2 b.
Rapidity
dN/d
y ( a
.u. )
p + pp + Pt
E888 acceptance
However, the predicted yield using a p + p type model for coalescence is H ~ 2 b.
In p + Pt collisions, there is significant strangeness enhancement and even greater enhancement of nearby baryons. The predicted yield should be H ~ 40 b.
Thus the ratio (limit/prediction) is still roughly the same. Nagle et al., Phys. Rev. C 53, 367 (1996).
Cole et al., Phys. Lett. B 350, 147 (1995).
E910 Lambda Distribution
nucl-ex/0003010 31 March 2000
distribution is shifted towards target rapidity.
p + Au at 18 GeV
Increasing number ofcollisions by the incoming proton
E799-II KTeV ResultNo candidates.
Sensitive to: H p
A. Alavi-Harati et al., Phys. Rev. Lett. 84, 2593 (2000).
< 12 pbKTeV sensitivity
Checking the Calculations
Rapidity
Inva
riant
Yie
ld (a
.u.)
p + Be at 800 GeV/cOriginal Model Calculation by Frank Rotondo. F. Rotondo, Phys. Rev. D 47, 3871 (1993).
Re-checked using transport model RQMD and coalescence. Agrees with previous prediction within a factor of 2.
< 12 pbKTeV sensitivity
~ 1.2 bmodel prediction
KTeV acceptance
E906 - HypernucleiIf one observes a double-lambda hypernucleus that decays by sequential weak decay, then it rules out all but the most weakly bound H dibaryon.
There are three isolated previous candidates - but the results are not consistent.
Recently E906 at the BNL-AGS reports a clear signal above background in the region where one expects to find the
4H.
Look for these results in the near future, and an upgrade proposal (Adam Rusek/Robert Chrien/Tomokazu Fukuda).
Double Lambda HypernucleiK- + (p) - + K+
- + (p) + + + A 4H + X
4H - + 4He
4He 3He + p + -
Beyond the H (|S| >2)Larger states of SQM can only be created with relativistic heavy ion collisions.
However, there are some issues:Too hot (higher energy)
- difficult to get multiple baryons close enough to fuseToo cool (lower energy)
- not enough strangeness production
AGS energies may be optimal, but there is still a large penalty for coalescence 1/48. Also, replacing a baryon unit with a strange baryon unit was predicted to be another ~ 1/5.
E864
Search for SQM with new Z/A
NA52 Experiment at CERN-SPS
No remaining candidates and thus set upper limits.
E886 (AGS) Adam Rusek
E878 (AGS) Mike Bennett
E864 (AGS) K.Barish, M.Munhoz, S.Coe, JN
E864 (AGS) Z.Xu, G.V.Buren, R. Hoverstein
NA52(CERN) R. Klingenberg, K.Pretzel
Lifetimes > 50 ns
T.A.Armstrong et al., Phys. Rev. Lett. 79, 3612 (1997)T.A.Armstrong et al., Nucl. Phys A 625, 494 (1997)D. Beavis et al., Phys. Rev. Lett. 75, 3078 (1995)A. Rusek et al., Phys. Rev. C 54, R15 (1996).R. Klingenberg et al., Nucl. Phys. A, 306c (1996).
No Evidence for SQM
A. Baltz et al., Phys. Lett. B 325, 7 (1994)H. Crawford et al., Phys. Rev. D 45, 857 (1992).H.C. Liu and G.L. Shaw, Phys. Rev. D 30, 1137 (1984).
Most plasma predictions ruled out by data
Sensitivity for SQM via coalescence up to states
A=6-7 , |S|=2-3
Nucleosynthesis Models
Quark Plasma Models
E864 Upper Limits
SQM Sensitivity
E864: Hypernuclei
If “SIGNAL”
invariant yield (2.6 + 1.2) 10-4 c2/Gev2
S = 1/28
If “LIMIT”
90% CL sensitivity 2.5 10-4 c2/Gev2
S < 1/30
Sotiria Batsouli, Yale University
(2.991 GeV)
e
J
.R.(e)= 25%
Y(A,|S|) = C x (1/48)A x (s)|S|
Unstable Nuclei5Li 4He + p (c ~ 100 fm/c)
Follows scaling law
Finite Size Effects
31
5.21
3
3
He
H
C
C
5.03
3
Hep
H
2r
Heinz, Scheibl, Phys. Rev. C59,1585 (1998).
= 5 fm B.E.( - 2H) = 0.13 Mev
e : = 1.74 fmE. = 8 MeV
Assume ( 2H +) with b = d 9.8 fm e ( 2H +p) with b = pd 2.6 fm
Using R|| , R | from E917, E895
2r
2r2r
Thus, accounting for lower abundance of ‘s and finite
size effects leaves an additional penalty of 0.5
Antideuterons
Corrected for large contribution of
antilambdas to measured antiprotons
T.A. Armstrong, Phys. Rev. Lett. 85, 2685 (2000).
E864
Res
ults
Ant
ideu
tero
n Y
iel d
s at t
h e A
GS
and
Co a
les c
ence
I mp l
ica t
ion s
, Phy
s . R
ev. L
ett .
85, 2
6 85
(20 0
0).
Mea
sur e
me n
ts o
f Lig
h t N
ucl e
i Pro
d uct
i on
i n 1
1.5A
GeV
/ c A
u +
Pb h
eavy
- ion
coll i
sio n
, Phy
s .Re v
.C61
: 064
90 ( 2
000)
. M
ass D
epe n
denc
e of
Lig
ht-N
ucl e
us P
rodu
c tio
n in
Ult r
are l
ati v
ist ic
Hea
v y-I
on C
oll is
ions
, Phy
s. R
ev. L
e tt 8
3 , 5
431
(19 9
9).
Sea r
ch fo
r neu
tral s
trang
e qu
ark
ma t
ter i
n h i
gh e
nerg
y he
avy
ion
col li
sio n
s, Ph
ys R
ev C
59,
R18
2 9 ( 1
999)
.A
ntin
prot
o n p
r odu
ctio
n a n
d an
ti deu
tero
n p r
odu c
ti on
l imi ts
in re
l ativ
isti c
he a
vy io
n co
llisi
ons ,
Phys
Rev
C 5
9, 2
699
(199
9 ).
Mea
sur e
me n
ts o
f neu
tron s
in 1
1 .5A
Ge V
/c A
u +
P b h
eav y
-ion
c olli
s ion
s, P h
ys R
e v C
60,
064
903
(199
9 ).
Ant
ipro
ton
Pro d
uctio
n in
11.
5 A
GeV
/c A
u+Pb
Nu c
leu s
-Nuc
l eus
Co l
lisi o
ns, P
h ys R
ev L
e tt 7
9 , 3
3 51
(19 9
7).
Sea r
ch fo
r Cha
rge d
Stra
n ge
Qua
rk M
att e
r in
11.5
AG
eV/ c
Au+
P b C
olli s
ion s
, Phy
s Re v
Let
t 79,
361
2 (1
997 )
. Se
a rch
for E
xotic
Stra
nge
Qu a
rk M
a tte
r in
Hig
h E n
erg y
Nuc
lear
Re a
cti o
ns N
u cl P
hys A
6 25
( 199
7) 4
94-5
1 2.
• Concept of a deeply bound H dibaryon may be on its last legs.• E906 and other KEK hypernuclei results will play a key role.• There is still a window at around 1/2 for a weakly bound H
dibaryon or bound state.• Or are the productions models really wrong (?)
• For A > 2 SQM almost final limits from fixed target programs.• In absence of observations, limits of a few 10-9 are reached.• Much harder to find many strange baryons close together than
initially predicted. Hypernuclei are also suppressed (?)
• RHIC is next step for heavy ion physics, but not SQM physics• Future experiments looking for multi-strange hypernuclei and
shorter lifetime SQM at Japanese Hadron Facility (?)
Conclusions and Future
Good Discussions
I want to acknowledge useful and fun discussions in preparing forthis talk with
Frank RotondoAdam RusekBill ZajcSebastian WhiteBob CousinsJosh KleinRam Ben-DavidJurgen Schaffner-BielichJack SandweissSotiria Batsouli
and many others……..
How does coalescence work?
Deuteron coalescence in p + A collisions
Deuteron coalescence in A + A collisions
Model Predictions for H dibaryon:How often are all the ingredients within the phase space (r, p) normally adequate to coalescence a deuteron from a proton-neutron pair.
p n
Nagle et al., Phys. Rev. C 53, 367 (1996).
= 2 fm B.E.( - 3H) = 2.04 Mev
e : = 1.4 fmE. = 29 MeV
Size effects not important
But weakly bound breaks easily
strong unstable nucleus
(2J + 1) = 4 , (2J + 1) = 10
Then, not much additional penalty for strangeness.
Other Hypernuclei
MeV
J
J
(3.92 GeV)
10412.04.0
4
4
Hn
H
2r
.R.(e)= 50%
2r
Recommended