document: first evidence of the violation of time reversal symmetry has been found in the kaon system  @xcite . despite strong efforts no other signal of violation of time 
   reversal symmetry has been found to date . 
   however , by now , studying time reversal symmetry has become a corner stone of the search for physics beyond the standard model of elementary particles  @xcite . 
   some alternatives or extensions of the standard model are due to dynamical symmetry breaking , multi higgs models , spontaneous symmetry breaking , grand unified theories ( e.g. so(10 ) ) , extended gauge groups ( leading e.g. to right - handed bosons @xmath3 in left - right symmetric models ) , super symmetric ( susy ) theories , etc . 
   , each implying specific ways of @xmath4 violation . 
   for a recent review of models relevant in the context of @xmath4 violation see e.g.  @xcite , and refs . therein . 
   these theories `` beyond '' the standard model are formulated in terms of quarks and leptons whereas nuclear low energy tests of @xmath4 involve hadronic degrees of freedom ( mesons and nucleons )  @xcite . to extract hadronic degrees of freedom from observables one may introduce effective @xmath1odd nucleon nucleon potentials  @xcite , or more specific @xmath1odd mesonic exchange potentials  @xcite . as in the context of @xmath0-violation 
   see e.g.  @xcite , these potentials have been proven quite useful to treat the nuclear structure part involved and to extract effective @xmath1odd hadronic coupling constants  @xcite . in turn 
   they allow to compare the sensitivity of different experiments , which has been done recently in ref . 
   however , in order to compare upper bounds on a more fundamental level of @xmath1odd interactions , it is necessary to relate hadronic degrees of freedom to quark degrees of freedom in some way . 
   this step is hampered by the absence of a complete solution of quantum chromo dynamics ( qcd ) at the energies considered here . in many cases a rough estimate in the context of time 
   reversal violation may be sufficient , and , in the simplest case , factors arising from hadronic structure may be neglected . in the context of @xmath0odd time reversal violation 
   e.g. concepts such as pcac and current algebra  @xcite have been utilized to improve the evaluation of hadronic structure effects . in the @xmath0even case , which is considered here , 
   this approach is not applicable ( no goldstone bosons involved here ) . 
   however , it may be useful to utilize quark models specifically designed for and quite successful in describing the low energy sector . 
   in fact , experimental precision tests still continue to make progress and so theorists face a renewed challenge to translate these experimental constrains to a more fundamental interaction level . 
   the purpose of the present paper is to give estimates on hadronic matrix elements that arise when relating quark operators to the effective hadronic parameterizations of the @xmath0even @xmath1odd interaction . 
   these are the charge @xmath2 type exchange and the axial vector type exchange nucleon nucleon interaction  @xcite 
   . they will shortly be outlined in the next section . 
   the ansatz to calculate @xmath5 matrix elements from the quark structure is described in section iii . 
   the last section gives the result for different types of quark models and a conclusion . 
   for completeness , note that in general also @xmath1-odd and @xmath0-odd interactions are possible , and in fact most of the simple extensions of the standard model mentioned above give rise to such type of @xmath1violation . 
   parameterized as one boson exchanges they lead e.g. to effective pion exchange potentials that are essentially long range , see  @xcite . 
   limits on @xmath0odd @xmath1odd interactions are rather strongly bound by electric dipole moment measurements , in particular by that of the neutron  @xcite . 
   in contrast bounds on @xmath0even @xmath1odd interactions are rather weak . 
   note , also that despite theoretical considerations  @xcite new experiments testing generic @xmath1odd @xmath0even observables have been suggested ; for the present status see e.g. refs . 
   due to the moderate energies involved in nuclear physics tests of time reversal symmetry , hadronic degrees of freedom are useful and may be reasonable to analyze and to compare different types of experiments . 
   for a recent discussion see ref . 
   @xcite . in the following only @xmath1-odd and @xmath0-_even _ interactions will be considered . 
   they may be parameterized in terms of effective one boson exchange potentials . due to the behavior under @xmath6 , 
   @xmath0 , and @xmath1 symmetry transformations , see e.g.  @xcite , two basic contributions are possible then : a charged @xmath2 type exchange  @xcite and an axial vector exchange  @xcite . 
   the effective @xmath2 type @xmath1odd interaction is @xmath6odd due to the phase appearing in the isospin sector and is only possible for charged @xmath2 exchange . 
   it has been suggested by simonius and wyler , who used the tensor part to parameterize the interaction  @xcite , @xmath7 there is some question of whether to choose an `` anomalous '' coupling  @xcite , viz . @xmath8 . 
   the numerical value of @xmath9 is usually taken to be @xmath10 close to the strong interaction case  @xcite . 
   we shall see in the following that it is not unreasonable to introduce such a factor since in may be related to `` nucleonic structure effects '' , which are not of @xmath1 violating origin ( similar to nuclear structure effects that are also treated separately ) . combining the @xmath1odd vertex with the appropriate @xmath1even vertex leads to the following effective @xmath1odd @xmath0even one boson exchange @xmath5 interaction , @xmath11 where @xmath12 , and 
   @xmath13 , and @xmath14 is the strong coupling constant , as e.g. provided by the bonn potential  @xcite . 
   the axial vector type interaction has been suggested by  @xcite . unlike the @xmath2type interaction the isospin dependence is not restricted and may be isoscalar , vector , and/or tensor type . 
   the effective lagrangian for the @xmath15 coupling for example is given by @xmath16 combined with the appropriate @xmath1even vertex this leads to an effective axial vector type exchange @xmath5 potential  @xcite , @xmath17 the bounds on the @xmath1odd coupling strengths arising from various experiments have been discussed in ref . 
   a more recent bound not included there is from an improved analysis  @xcite of the @xmath18fe @xmath19decay experiment  @xcite . 
   bounds are in the order of 10% if derived from generic @xmath1odd @xmath0even observables and slightly more than an order of magnitude smaller , if related to the electric dipole moments  @xcite . to complete this section , note 
   that although possible , two boson exchanges have not been considered up to now . 
   we now turn to effective @xmath1-odd @xmath0-even quark operators . the simplest operator that leads to an effective @xmath1odd @xmath0even vector type vertex @xmath20 analogous to the @xmath2type interaction eq . 
   ( [ eqn : vnn ] ) is @xmath21 here @xmath22 , @xmath23 denote flavored quark fields . 
   again the flavor dependence is responsible for @xmath6 , viz . 
   @xmath1violation due to the phase dependence . 
   a tensor term has not been introduced for simplicity . on the basis of eq . 
   ( [ quarkv ] ) such a term will arise in a natural way in the effective hadronic @xmath24 @xmath1-odd lagrangian through the quark structure effects as will be explained below . 
   the second generic quark operator utilizing axial vector bilinear operators is given by  @xcite , @xmath25 with the on  shell equivalent @xmath26    in order to recover eqs . 
   ( [ eqn : vnn ] ) and ( [ eqn : ann ] ) we utilize the constituent quark model . 
   this model has been rather successful and valuable in reproducing gross features of low energy phenomenae , such as mass spectra , form factors , coupling constants , magnetic moments etc . 
   , see e.g.  @xcite .    to relate quark operators to effective hadronic operators we utilize the fock space representation of hadrons in terms of constituent quarks , viz . 
   @xmath27 since there is no low energy solution of qcd , the evaluation of the matrix elements of the l.h.s of eq . 
   ( [ fock ] ) needs further consideration . in general 
   , the same problem arises in the context of strong interactions . 
   an extensive overview of the different approaches to tackle the problem in this case has been given by ref . 
   @xcite . here 
   we follow the ideas first formulated in ref . 
   @xcite , and extensively studied for different quark models in  @xcite . 
   the resulting strong interaction potential is a generic hybrid model connecting quark degrees of freedom with effective meson nucleon degrees of freedom . 
   the basic idea is summarized in the following . 
   suppose the two nucleons overlap , and two quarks are sufficiently close together . 
   this situation is depicted in figure  [ fig : qqnn]a ) . 
   then , to begin with , the matrix elements may be evaluated without introducing any mesonic fields . in terms of the constituent quark model @xmath28 excitations 
   are neglected ( or partially parameterized in the constituent quark mass ) . only at larger distances of the nucleons , 
   mesons are essential and may appear as @xmath28 correlations on the nonperturbative qcd vacuum  @xcite that might be the physical vacuum of the low energy regime  @xcite . 
   however , the appearance of mesons is disconnected from the problem of @xmath1odd force . 
   therefore , in the following we assume that the hadronization mechanism is the _ 
   same for both @xmath1odd and the usual @xmath1even strong interaction _ and investigate the relative strength of the @xmath1odd matrix elements to the @xmath1even matrix elements . 
   this is done in the framework of the virginia potential that assumes a quark pairing mechanism to generate effective meson nucleon coupling constants  @xcite . to illustrate the quality of this ansatz table  [ tab : virginia ] 
   shows the resulting coupling constants using different quark models compared to the values of a recent version of the bonn potential  @xcite .    in this framework 
   we utilize the factorization approximation to evaluate the matrix element of eq . 
   ( [ fock ] ) , see figure  [ fig : qqnn]b ) @xmath29 to demonstrate the calculation , we use the simple constituent quark model . 
   this model is supplemented by an explicit lower component , which already occurs implicitly in the dirac magnetic moments  @xcite and in the two 
   body pair current through electromagnetic gauge invariance  @xcite . 
   this way a treatment of relativistic effects has been introduced , see e.g.  @xcite and ref . therein . 
   the integration of the internal degrees of freedom reads , @xmath30\ ] ] with @xmath31 the three quark wave internal function . in the rest system the space part of the wave function 
   is given by  @xcite @xmath32\ ] ] where numerical values may be chosen as @xmath33 , and @xmath34 . 
   the coordinates are normalized lovelace coordinates , viz . 
   @xmath2 for the pair and @xmath35 for the odd quark . 
   integration is done in the breit system . 
   the symbol @xmath36 denotes either one of the vertices in ( [ quark ] ) . 
   evaluation for the different type of operators leads to the following expressions ( using the isospin formalism for @xmath37 quarks ) @xmath38 the factors arising are related to the quark structure of nucleons . 
   note , that in eq . 
   ( [ axial ] ) one recognizes the well known coupling of the axial vector current ( for @xmath39 ) , viz . 
   @xmath40 of the nonrelativistic constituent quark model , besides factors arising from relativistic corrections due to the lower dirac component . 
   the latter reduce the value of @xmath41 close to the experimental one  @xcite . in eq . 
   ( [ tensor ] ) a tensor coupling appears , which belongs to the @xmath2 type @xmath1odd exchange . indeed due to the quark structure factors its relative strength is larger than the first term of the r.h.s . of eq . 
   ( [ tensor ] ) , and therefore preferable in an ansatz of a @xmath2type @xmath1odd force as done by simonius and wyler  @xcite . 
   the factor in front the tensor term may be interpreted as `` anomalous '' coupling . 
   it appears in analogy to the electromagnetic interaction , where the pauli term of the electromagnetic photon nucleon interaction can be recovered from a pure dirac coupling on quark level . 
   this has been explained and shown in ref . 
   the resulting relation between quark and hadronic @xmath1odd coupling strength on the basis of the constituent quark model is , for @xmath2 type exchange @xmath42 and for axial type of exchange @xmath43 here the expression for isoscalar and isovector are the same . 
   similar results may be obtained using different types of quark models . in the context of the virginia potential 
   those studied are the mit bag model and a relativistic model with linear confining potential , see ref . 
   these are used here in the same way as demonstrated for the constituent quark model in the previous section . 
   the values for the quark structure effects evaluated using typical quark model parameters of low energy phenomenology are given in table  [ tab : values ] . 
   in fact , due to the symmetries inherent in the quark pairing mechanism ( viz . 
   the virginia potential ) it is possible to arrive at the following relations between the coupling constants , viz . 
   @xmath44 this equation shows that the factors appearing in the @xmath45 type exchange may be related to the anomalous coupling @xmath46 . 
   so , inclusion of @xmath9 might give a bound closer to the more basic quark degrees of freedom .    in conclusion 
   , provided the hadronization process does not substantially differ for @xmath1odd and @xmath1even interactions , the factors arising reflect the _ nucleon _ structure effects . 
   the origin of the structure factors are due to the spin , isospin structure and the different mass scales ( i.e. @xmath47 vs. @xmath48 ) . 
   these have also been essential in deriving the relative strength of the strong coupling constants as given in table  [ tab : virginia ] . 
   the author gratefully acknowledges support by the national institute for nuclear theory at the university of washington , seattle , during his stay on the int program `` physics beyond the standard model at low and intermediate energies '' . this work has been supported by deutsche forschungsgemeinschaft 
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   a_1(119 )    & ( 1^{++},1 ^ -)&1.0 & [ -1.5 ] & 0.6 &   & 1.64 & [ 0 ]     & & \\ 
   \hline\hline \end{array}\ ] ]
summary: tests of time reversal symmetry at low and medium energies may be analyzed in the framework of effective hadronic interactions . here , we consider the quark structure of hadrons to make a connection to the more fundamental degrees of freedom . 
   it turns out that for @xmath0even @xmath1odd interactions hadronic matrix elements evaluated in terms of quark models give rise to factors of 2 to 5 . also , it is possible to relate the strength of the anomalous part of the effective @xmath2 type @xmath1odd @xmath0even tensor coupling to quark structure effects .