GLUON CONDENSATES AS SUSCEPTIBILITY RELATIONS

Transcription

1 GLUON CONDENSATES AS SUSCEPTIBILITY RELATIONS Roman Zwicky Edinburgh University 14 Nov 2014 Strong Dynamics in the LHCera Bad Honnef

2 Main result to be derived and discussed M 2 H = 1 2 hh(e H) 1 ḡ 2 Ḡ2 H(E H )i c GT= 1 2 h0 1 ḡ 2 Ḡ2 0i Del Debbio and RZ (PLB 2014) advocate: LHS provides a definition of the RHS direct computation of gluon condensates (RHS) plagued by power divergences no definite result known 0 G 2 0 = 0±0.012GeV 4 c.f. also Ioffe 05 indirect determinations * barred quantities correspond to renormalised quantities & c stands for connected E M H h0 T µ µ 0i = D GT

3 Overview Derivations (A) Feynman-Hellmann & Trace anomaly & RG-Eqs (B) Hamiltonian formalism (direct use of FH-thm) Illustration in exactly solvable models How to implement coupling derivative Where it cam from: corrections to scaling of the mass(-operator) Epilogue (applications) Backup slides: - comment energy momentum tensor on lattice - issue of Konishi-anomaly

4 two derivations

5 (A) trace anomaly, Feynman-Hellmann-thm & RGE Feynman-Hellmann thm: E = ( ) Ĥ( ) ( ) Del Debbio and RZ (PLB 2014) idea: ( ) ( ) =0 useful provided H(λ) known (QFT different normalisation has to be taken into account) example H(m) = m M 2 = N F h qq i c For λ=g (gauge coupling) complicated since A0 not dynamical. Show: if use all ingredients in the title then we can get relations! Fix notation H(adron) : H(E, p ) H(E, p) =2E( p)(2 ) D 1 (D 1) ( p p ), X EH H(E,p) X H(E,p) c, Q N f m qq, G g 2 G A G A, three step procedure.

6 Adler et al, Collins et al N.Nielsen 77 Fujikawa EM-tensor & trace anomaly : T µ µ on shell = Evaluate on physical state H one gets: 2ḡ Ḡ +(1+ m) Q, for gauge theory (bar renormalised quantities important!) 2MH 2 = 2ḡ ḠE H +(1+ m ) Q EH, D GT = 2ḡ Ḡ 0 +(1+ m ) Q Feynman-Hellmann-thm (mass) trace anomaly (1) m m E 2 H = Q EH, m m (D GT )= Q 0. FH-thm (2) 3. Renormalization group equation ḡ (1 + m ) m m +2 MH 2 = 0, ḡ (1 + m ) m m + D GT = 0,

7 Combining our results takes on the form: ḡ ḡ E 2 H = 1 2 Ḡ E H, ḡ ḡ GT = 1 2 Ḡ 0.

8 (B) After all from the Hamiltonian formalism Prochazka and RZ JPA guiding question: H-formalism is non-covariant! how Lorentz invariance emerge? ~ = ~ E, ~ A indep. canonical variables ( 0 = 0, A 0 Lagrangian multiplier) [A k (x 0, ~x),e l (x 0, ~y)] = i k l (D 1) (~x ~y) 1 2 ( ~ E 2 + ~ B 2 ) q(i~ ( + ig ~ A) m)q 2B k = kij G ij = kij (@ i A j A i + ig[a i,a j ]) primary, secondary constraints Gauss constraint A a 0(( ~ D ~E) a + qt a 0q) step 1: only Hg non-vanishing on physical states - drop HC,G step 2: put g s into right place by performing canonical transformation: ~ A! 1 g ~ A, ~ E! g ~ E

9 a) leaves can. commutator invariant b) no rescaling (Konishi) anomaly (non-trivial) H g = 1 2 (g2 ~ E g 2 ~ B 2 ) q(i~ ~@ + i ~ A + m)q the pathway to a Lorentz-invariant result is now H g = g 2 ~ E 2 1 g 2 ~ B 2 = g 2 G µ G µ very same relations (as before) emerge ḡ ḡ E 2 H = 1 2 Ḡ E H, ḡ ḡ GT = 1 2 Ḡ 0. advantage: the Hamiltonian derivation makes it clear that relation valid for product groups e.g. G = U(1)xSU(2)xSU(3)

10 illustration in exactly solvable models Schwinger model (QED2 massless fermions) photon mass e 2 /π massive flavoured Schwinger model cosmological constant N=2 SYM (Seiberg-Witten) monopole mass

11 Photon mass Schwinger model Schwinger model: QED2 mf=0 - generation of photon mass: M Ɣ =e/ M 2 = 1 2 h F 2 i c adaption 2D [e]=1 Lowenstein-Swieca operator solution can compute RHS F µ = p e µ Σ free field mass e 2 /π evaluate on photon state h F 2 i c = e 2 µ µ 2( M 2 ) 2 = 4 e2 Insert into equation above and M 2 =2 e2 ) M 2 = e2 + C boundary condition C=0 and this completes the illustration!

12 N=2 SYM (Seiberg-Witten) BPS states obey: M(e,m)= 2 ne a + nm ad 2 where a,ad part of SW-solution BPS-Hamiltonian magnetic monopoles (ne=0, B static Ē=0 & no fermions as BPS) H BPS = 1 g 2 ~ D ~D g 2 ~ B 2 BPS-eqn: ~D BPSi = 1 p 2 ~ B BPSi ) H BPS = 1 g 2 ~ B H BPS = 2 1 g ~ 2 B 2 E=0 ~ = shown main Eqn obeyed BPS-subspace 1 g 2 G2 N.B. additional factor 2 because of supersymmetry Unlike Schwinger model, can t compute RHS directly used LHS to get RHS= BPS G 2 BPS RHS governed by magnetic coupling gd e.g. RHS 0 for gd 0

13 Implementation of derivative coupling

14 Implementation is not so immediate in a theory with running coupling (depends on your background) lattice: every QCD parameter g,mu, md is associated with hadronic observable step 1: M = 770MeV measure coupling in scheme A: g A ( M )=c, c, 2 R step 2: M = 770(1 + )MeV measure coupling in scheme A: g A ( M )=c (= g A ( M ), where = 1+ ) * M =lim A!0 ga g A g A (x) =ga (x(1 + ))

15 Where it all came from

16 scaling correction to hadronic mass in near conformal phase Del Debbio and RZ (PRD 2013) consider conformal theory with mass deformation expand around fixed pt coupling g * = 1 g + O( g 2 ), g g g, m = m + (1) m g + O( g 2 ), ij = ij + (1) ij g + O( g 2 ), ( ij ( O ) ij ). g each local operator O investigate Callan-Symanzik-Weinberg- thooft type RGE ij + (g) g ij m m m ij ij O j (g, m, )=0 d UV-cut o :, m = d ln m.. correction to scaling to hadronic mass through a) RGE above applied to O = MH b) or apply scaling to all four quantities in trace anomaly 2M 2 H = Ḡ MH +(1+ m) 2ḡ Q MH, a) and b) agree only if susceptibility relation hold

17 Epilogue ḡ ḡ E 2 H = 1 2 Ḡ E H, ḡ ḡ GT = 1 2 Ḡ 0. Scheme dep. of RHS inherited from scheme dependence of coupling g LHS defines RHS - suggest total change of viewpoint (Recall: direct computation of G-condensate fails because power divergences mixing with lower dimensional operators e.g. identity (quartic UV-divergence)) Practice computation of H G 2 H (should be) straightforward a) lattice b) approaches like AdS/QCD or Dyson-Schwinger Eqn which produce MH opens up opportunities to define β and γm through interplay with trace anomaly: 2M 2 H = 2ḡ hh Ḡ2 Hi +(1+ m) mhh qq Hi For example if m =0 then ( YM) ln M H

18 Computation of 0 G 2 0 is more difficult per se - on lattice demands mastering EMT problems due to breaking of translation symmetry (additional renormalisation) recent progress using Wilson flow del Debbio,Patella, Rago JHEP(2014) check PCD(ilaton)C hypothesis for gauge theory dilation candidate (Higgs imposter) (analogue PCAC soft pion reduction) 2m 2 D = 2g hd G 2 Di + O(m q ) soft dilaton ' 2g 1 f 2 D h0 G 2 0i + O(m q ) hd G 2 0i = f D compute QCD contribution to cosmological constant N.B. practice mastering EMT already enough - yet relations useful in eliminating constant which is independent of g one could do conversion calculation to MS-bar and compare with value extracted from OPE (e.g. charmonium sum rules or SVZ sum rules) THANKS FOR YOUR ATTENTION

19 backup slides

20 renormalisation of energy momentum tensor (EMT) continuum EMT does not renormalise (ZTαβ =1) since conserved quantity (still need to renormalise parameters of theory of course) lattice break Lorentz symmetry to hyper cubic symmetry hence the EMT is not conserved anymore ZTαβ =1 does not apply or in other words we can write down further invariant with which the EMT mixes Problem: how to tune counterterms h0 Z translation Ward identity to probe EMT Caracciolo, Curci, Menotti, Pelissetto 90 d 3 xt 0µ (x) (x 1 )... (x n ) 0i = i ) µ h0 (x 1)... (x n ) 0i Problem: each probe contact term no gain using Wilson flow can avoid contact terms (probes are in bulk.) del Debbio,Patella, Rago JHEP(2014)

21 issue of konishi anomaly rescale field coupled to a gauge field by a constant then term appears G 2 like chiral transformation gives rise to G*G-term (supersymmetry same footing) perform transformation p-integral measure transforms as (same as Fujikawa chiral anomaly computation)