Next: Galilean and gauge invariance
Up: Construction of the energy
Previous: Construction of the energy
Terms in the energy density
Terms in the EDF we construct here are required to be quadratic in
densities, invariant with respect to time reversal
(Sec. A.1), and covariant with respect to space inversion and
rotations (Sec. A.2). All terms up to the NLO order in
derivatives fulfilling these restrictions are constructed below.
Using notation of Eq. (24), a general term in the
energy density can be written in the following form,
|
(28) |
where both densities must have the same rank to be coupled to a
scalar. Moreover, their time-reversal and space-inversion parities
( and ) must be the same. Again, at NLO only terms with
are allowed.
Then, the total energy density reads
|
(29) |
where
are coupling constants
and the summation runs over all allowed indices.
Had we considered the case of coupling constants depending on
density, all terms in Eq. (28) would have been
independent of one another (up to a possible exchange of the two
densities). Table 5 lists numbers of such
independent terms, and they are also plotted in Fig. 1.
Table 5:
Numbers of terms
defined in Eq. (28) of
different orders in the EDF up to NLO. Numbers of terms depending on
the time-even and time-odd densities are given separately. The last
two columns give numbers of terms when the Galilean or gauge
invariance is assumed, respectively, see Sec. 3.2.
To take into account both isospin channels, the numbers of terms
should be multiplied by a factor of two.
order |
T-even |
T-odd |
Total |
Galilean |
Gauge |
0 |
1 |
1 |
2 |
2 |
2 |
2 |
8 |
10 |
18 |
12 |
12 |
4 |
53 |
61 |
114 |
45 |
29 |
6 |
250 |
274 |
524 |
129 |
54 |
NLO |
312 |
346 |
658 |
188 |
97 |
Figure 1:
(Color online) Numbers of terms (28) and
(30) shown in
Tables 5 and
6, respectively, plotted in
logarithmic scale as a function of the order in derivatives.
|
In the present study, we concentrate on the case of
density-independent coupling constants, in which case one can perform
integrations by parts, so that the derivative operators are
transferred from one density to the other. That this can always be
done is obvious by the fact that the coupled derivative operators
can always be expressed as sums of products of uncoupled
derivatives
or . As a result of the
integration by parts, the integral (28) can now be written
as a sum of terms, where each term has the form:
|
(30) |
where ranks and are coupled to .
Here, at NLO (i) only terms with
are allowed, (ii)
both densities must have the same time-reversal parity ,
and (iii) their space-inversion parities must differ by factors . Finally, in order
to avoid double-counting one takes only terms with , and for
only those with , and for
only those with , and for
only those with .
Then, the total energy density reads
|
(31) |
where
are coupling constants and the
summation again runs over all allowed indices. As we did for the
local densities above, to better visualize the time-reversal
characteristics of terms in the EDF, the coupling constants
corresponding to terms that depend on
time-even densities are shown in bold face.
Based on the results obtained in Secs. A.1 and
A.2, and on Eqs. (25) and (26),
we see that time-reversal invariance and space-inversion
covariance require that
respectively. This means that integers , , and must
be simultaneously either even or odd. The numbers of all such
allowed terms are given in Table 6 and plotted
in Fig. 1. The space-inversion
covariance (33) requires that for all terms, the total orders in derivatives
are even numbers, which defines our classification of the EDF up to LO
(0), NLO (2), NNLO (4), and NLO (6).
Table 6:
Same as in
Table 5, but for numbers of terms
defined in Eq. (30).
order |
T-even |
T-odd |
Total |
Galilean |
Gauge |
0 |
1 |
1 |
2 |
2 |
2 |
2 |
6 |
6 |
12 |
7 |
7 |
4 |
22 |
23 |
45 |
15 |
6 |
6 |
64 |
65 |
129 |
26 |
6 |
NLO |
93 |
95 |
188 |
50 |
21 |
In Appendix B, we presented terms in the EDF up to NLO,
i.e., for zero and second orders, see Table 22. The EDF at NLO
is exactly equivalent to the standard Skyrme functional
[28,29], generalized to include all time-odd terms
[25,30,24]. In both representations the
functional depends, in general, on 14 coupling constants, and both
sets are related by simple expressions given in
Eqs. (93)-(106).
In Tables 7-18, we list all 45 and 129
terms in the EDF that are of fourth and sixth order, respectively.
Together with 14 terms at NLO, listed in Table 22, this
constitutes the full list of 188 terms in the EDF at NLO.
Table 7:
Terms in the EDF
(30) that are of fourth order, depend on
time-even densities, and are built from the scalar nonlocal density
. Coupling constants corresponding to terms
that depend on time-even densities are marked by using the bold-face
font. Bullets () mark coupling constants corresponding to
terms that do not vanish for conserved spherical, space-inversion,
and time-reversal symmetries, see Sec. 4.
No. |
|
|
|
|
|
1 |
|
|
|
|
|
2 |
|
|
|
|
|
3 |
|
|
|
|
|
4 |
|
|
|
|
|
5 |
|
|
|
|
|
6 |
|
|
|
|
|
Table 8:
Same as in Table 7 but for terms
that are built from the vector
nonlocal density
.
No. |
|
|
|
|
|
7 |
|
|
|
|
|
8 |
|
|
|
|
|
9 |
|
|
|
|
|
10 |
|
|
|
|
|
11 |
|
|
|
|
|
12 |
|
|
|
|
|
13 |
|
|
|
|
|
14 |
|
|
|
|
|
15 |
|
|
|
|
|
16 |
|
|
|
|
|
17 |
|
|
|
|
|
Table 9:
Same as in Table 7 but for terms
that are built from
the scalar nonlocal density
and vector
nonlocal density
.
No. |
|
|
|
|
|
18 |
|
|
|
|
|
19 |
|
|
|
|
|
20 |
|
|
|
|
|
21 |
|
|
|
|
|
22 |
|
|
|
|
|
Table 10:
Terms in the EDF (30)
that are of fourth order,
depend on time-odd densities, and are built from
the scalar nonlocal density
.
No. |
|
|
|
|
23 |
|
|
|
|
24 |
|
|
|
|
25 |
|
|
|
|
Table 11:
Same as in Table 10 but for terms
that are built from the vector
nonlocal density
.
No. |
|
|
|
|
26 |
|
|
|
|
27 |
|
|
|
|
28 |
|
|
|
|
29 |
|
|
|
|
30 |
|
|
|
|
31 |
|
|
|
|
32 |
|
|
|
|
33 |
|
|
|
|
34 |
|
|
|
|
35 |
|
|
|
|
36 |
|
|
|
|
37 |
|
|
|
|
38 |
|
|
|
|
39 |
|
|
|
|
40 |
|
|
|
|
Table 12:
Same as in Table 10 but for terms
that are built from
the scalar nonlocal density
and vector
nonlocal density
.
No. |
|
|
|
|
41 |
|
|
|
|
42 |
|
|
|
|
43 |
|
|
|
|
44 |
|
|
|
|
45 |
|
|
|
|
Table 13:
Terms in the EDF
(30) that are of sixth order, depend on
time-even densities, and are built from the scalar nonlocal density
. Coupling constants corresponding to terms
that depend on time-even densities are marked by using the bold-face
font. Bullets () mark coupling constants corresponding to
terms that do not vanish for conserved spherical, space-inversion,
and time-reversal symmetries, see Sec. 4.
No. |
|
|
|
|
|
1 |
|
|
|
|
|
2 |
|
|
|
|
|
3 |
|
|
|
|
|
4 |
|
|
|
|
|
5 |
|
|
|
|
|
6 |
|
|
|
|
|
7 |
|
|
|
|
|
8 |
|
|
|
|
|
9 |
|
|
|
|
|
10 |
|
|
|
|
|
11 |
|
|
|
|
|
12 |
|
|
|
|
|
Table 14:
Same as in Table 13 but for terms
that are built from the vector
nonlocal density
.
No. |
|
|
|
|
|
13 |
|
|
|
|
|
14 |
|
|
|
|
|
15 |
|
|
|
|
|
16 |
|
|
|
|
|
17 |
|
|
|
|
|
18 |
|
|
|
|
|
19 |
|
|
|
|
|
20 |
|
|
|
|
|
21 |
|
|
|
|
|
22 |
|
|
|
|
|
23 |
|
|
|
|
|
24 |
|
|
|
|
|
25 |
|
|
|
|
|
26 |
|
|
|
|
|
27 |
|
|
|
|
|
Table 14:
continued.
No. |
|
|
|
|
|
28 |
|
|
|
|
|
29 |
|
|
|
|
|
30 |
|
|
|
|
|
31 |
|
|
|
|
|
32 |
|
|
|
|
|
33 |
|
|
|
|
|
34 |
|
|
|
|
|
35 |
|
|
|
|
|
36 |
|
|
|
|
|
37 |
|
|
|
|
|
38 |
|
|
|
|
|
39 |
|
|
|
|
|
40 |
|
|
|
|
|
41 |
|
|
|
|
|
42 |
|
|
|
|
|
43 |
|
|
|
|
|
44 |
|
|
|
|
|
45 |
|
|
|
|
|
46 |
|
|
|
|
|
47 |
|
|
|
|
|
Table 15:
Same as in Table 13 but for terms
that are built from
the scalar nonlocal density
and vector
nonlocal density
.
No. |
|
|
|
|
|
48 |
|
|
|
|
|
49 |
|
|
|
|
|
50 |
|
|
|
|
|
51 |
|
|
|
|
|
52 |
|
|
|
|
|
53 |
|
|
|
|
|
54 |
|
|
|
|
|
55 |
|
|
|
|
|
56 |
|
|
|
|
|
57 |
|
|
|
|
|
58 |
|
|
|
|
|
59 |
|
|
|
|
|
60 |
|
|
|
|
|
61 |
|
|
|
|
|
62 |
|
|
|
|
|
63 |
|
|
|
|
|
64 |
|
|
|
|
|
Table 16:
Terms in the EDF
(30) that are of sixth order, depend on
time-odd densities, and are built from the scalar nonlocal density
.
No. |
|
|
|
|
65 |
|
|
|
|
66 |
|
|
|
|
67 |
|
|
|
|
68 |
|
|
|
|
69 |
|
|
|
|
70 |
|
|
|
|
71 |
|
|
|
|
72 |
|
|
|
|
Table 17:
Same as in Table 16 but for terms
that are built from the vector
nonlocal density
.
No. |
|
|
|
|
73 |
|
|
|
|
74 |
|
|
|
|
75 |
|
|
|
|
76 |
|
|
|
|
77 |
|
|
|
|
78 |
|
|
|
|
79 |
|
|
|
|
80 |
|
|
|
|
81 |
|
|
|
|
82 |
|
|
|
|
83 |
|
|
|
|
84 |
|
|
|
|
85 |
|
|
|
|
86 |
|
|
|
|
87 |
|
|
|
|
88 |
|
|
|
|
89 |
|
|
|
|
90 |
|
|
|
|
Table 17:
continued.
No. |
|
|
|
|
91 |
|
|
|
|
92 |
|
|
|
|
93 |
|
|
|
|
94 |
|
|
|
|
95 |
|
|
|
|
96 |
|
|
|
|
97 |
|
|
|
|
98 |
|
|
|
|
99 |
|
|
|
|
100 |
|
|
|
|
101 |
|
|
|
|
102 |
|
|
|
|
103 |
|
|
|
|
104 |
|
|
|
|
105 |
|
|
|
|
106 |
|
|
|
|
107 |
|
|
|
|
108 |
|
|
|
|
109 |
|
|
|
|
110 |
|
|
|
|
111 |
|
|
|
|
112 |
|
|
|
|
Table 18:
Same as in Table 16 but for terms
that are built from
the scalar nonlocal density
and vector
nonlocal density
.
No. |
|
|
|
|
113 |
|
|
|
|
114 |
|
|
|
|
115 |
|
|
|
|
116 |
|
|
|
|
117 |
|
|
|
|
118 |
|
|
|
|
119 |
|
|
|
|
120 |
|
|
|
|
121 |
|
|
|
|
122 |
|
|
|
|
123 |
|
|
|
|
124 |
|
|
|
|
125 |
|
|
|
|
126 |
|
|
|
|
127 |
|
|
|
|
128 |
|
|
|
|
129 |
|
|
|
|
Table 19:
Numbers of local densities
, Eq. (23), of different orders, which enter
into the EDF up to NLO. Numbers of local densities constructed from
the scalar
or vector
nonlocal densities, and numbers of
time-even and time-odd local densities, are given separately. In
Tables 3 and 4 these densities are marked with
stars ().
order |
from |
from |
T-even |
T-odd |
total |
0 |
1 |
1 |
1 |
1 |
2 |
1 |
1 |
3 |
3 |
1 |
4 |
2 |
2 |
4 |
2 |
4 |
6 |
3 |
2 |
6 |
6 |
2 |
8 |
4 |
2 |
5 |
2 |
5 |
7 |
5 |
1 |
4 |
4 |
1 |
5 |
6 |
1 |
2 |
1 |
2 |
3 |
total |
10 |
25 |
19 |
16 |
35 |
After the complete list of terms in the EDF at NLO is
constructed, one can check that not all of the local densities listed
in Tables 3 and 4 appear in the final EDF at
NLO. This is so, because it is not possible to couple all these
densities to scalars, and simultaneously fulfill conditions
(32) and (33), without obtaining more than total
sixth order in derivatives. It turns out that out of the 56 local
densities at NLO, which are listed in Tables 3 and
4, only 35 occur in the final EDF at NLO. In
Tables 3 and 4 such densities are marked with
stars (). Table 19 gives their numbers determined
separately at each order.
Next: Galilean and gauge invariance
Up: Construction of the energy
Previous: Construction of the energy
Jacek Dobaczewski
2008-10-06