Tue·Sep 6, 2016Tuesday·September 6, 2016

1. 01*

   Families from Supergroups and Predictions for Leptonic CP Violation

   S.M. Barr🇺🇸 · Heng-Yu Chen🇺🇸

   As was shown in 1984 by Caneschi, Farrar, and Schwimmer, decomposing representations of the supergroup SU(M|N), can give interesting anomaly-free sets of fermion representations of SU(M) x SU(N) x U(1). It is shown here that such groups can be used to construct realistic grand unified models with non-abelian gauged family symmetries. A particularly simple three-family example based on SU(5) x SU(2) x U(1) is studied. The forms of the mass matrices, including that of the right-handed neutrinos, are determined in terms of SU(2) Clebsch coefficients; and the model is able to fit the lepton sector and predict the Dirac CP-violating phase of the neutrinos.. Models of this type would have a rich phenomenology if part of the family symmetry is broken near the electroweak scale.

   hep-phJHEP(2017)·1 citation
2. 02*

   Analytical On-shell Calculation of Low Energy Higher Order Scattering

   Barry R. Holstein🇺🇸

   We demonstrate that the use of analytical on-shell methods involving calculation of the discontinuity across the t-channel cut associated with the exchange of a pair of massless particles (photons or gravitons) can be used to evaluate one-loop contributions to electromagnetic and gravitational scattering, with and without polarizability, reproducing via simple algebraic manipulations, results obtained previously, generally using Feynman diagram techniques. In the gravitational case the use of factorization permits a straightforward and algebraic calculation of higher order scattering without consideration of ghost contributions or of triple-graviton couplings, which made previous evaluations considerably more arduous.

   hep-phgr-qchep-thnucl-thJ.Phys.G(2017)·21 citations
3. 03*

   Revisiting the equivalence of light-front and covariant QED in the light-cone gauge

   Luca Mantovani🇮🇹 · Barbara Pasquini🇮🇹 · Xiaonu Xiong🇮🇹 · Alessandro Bacchetta🇮🇹

   We discuss the equivalence between light-front time-ordered-perturbation theory and covariant quantum field theory in light-front quantization, in the case of quantum electrodynamics at one-loop level. In particular, we review the one-loop calculation of the vertex correction, fermion self-energy and vacuum polarization. We apply the procedure of integration by residue over the light-front energy in the loop to show how the perturbative expansion in covariant terms can be reduced to a sum of propagating and instantaneous diagrams of light-front time-ordered perturbation theory. The detailed proof of equivalence between the two formulations of the theory resolves the controversial question on which form should be used for the gauge-field propagator in the light-cone gauge in the covariant approach.

   hep-phnucl-thPRD(2016)·14 citations
4. 04*

   Discussion on Lorentz Invariance Violation of Non-commutative Field Theory and Neutrino Oscillation

   Cui-Bai Luo🇨🇳 · Song Shi🇨🇳 · Yi-Lun Du🇨🇳 · Yong-Long Wang🇨🇳 · Hong-Shi Zong🇨🇳

   Depending on deformed canonical anti-commutation relations, massless neutrino oscillation based on Lorentz invariance violation in non-commutative field theory is discussed. It is found that the previous studies about massless neutrino oscillation within deformed canonical anti-commutation relations should satisfy the condition of new Moyal product and new non standard commutation relations. Furthermore, comparing the Lorentz Invariant Violation parameters $A$ in the previous studies with new Moyal product and new non standard commutation relations, we find that the orders of magnitude of non-commutative parameters (Lorentz invariant Violation parameters $A$) is not self-consistent. This inconsistency means that the previous studies of Lorentz invariance violation in non-commutative field theory may not naturally explain massless neutrino oscillation. In other words, it should be impossible to explain neutrino oscillation by Lorentz invariance violation in non-commutative field theory. This conclusion is supported by the latest atmospheric neutrinos experimental results from the Super-Kamiokande Collaboration, which show that no evidence of Lorentz invariance violation on atmospheric neutrinos was observed.

   hep-phInt.J.Mod.Phys.A(2017)·1 citation
5. 05*

   Theory overview of electroweak physics at hadron colliders

   John M. Campbell🇺🇸

   This contribution summarizes some of the important theoretical progress that has been made in the arena of electroweak physics at hadron colliders. The focus is on developments that have sharpened theoretical predictions for final states produced through electroweak processes. Special attention is paid to new results that have been presented in the last year, since LHCP2015, as well as on key issues for future measurements at the LHC.

   hep-phPoS(2016)·2 citations
6. 06*

   Restrained Dark $U(1{)}_d$ at Low Energies

   F. C. Correia🇧🇷 · Svjetlana Fajfer🇸🇮

   We investigate a spontaneously broken $U(1{)}_d$ gauge symmetry with a muon-specific dark Higgs. Our first goal is to verify how the presence of a new dark Higgs, $\varphi$, and a dark gauge boson, $V$, can simultaneously face the anomalies from the muon magnetic moment and the proton charge radius. Secondly, by assuming that $V$ must decay to an electron-positron pair, we explore the corresponding parameter space determined with the low energy constraints coming from $K\to \mu X$, electron $(g-2{)}_e$, $K\to \mu {\nu }_{\mu }{e}^{+}{e}^{-}$, $K\to \mu {\nu }_{\mu }{\mu }^{+}{\mu }^{-}$, $\tau \to {\nu }_{\tau }\mu {\nu }_{\mu }{e}^{+}{e}^{-}$. We focus in the scenario where the $V$ mass is below $\sim 2m_{\mu }$ and the $\varphi$ mass runs from few MeV till $250$ MeV, with V-photon mixing of the order $\sim \mathcal{O}(10^{-3})$. Among weak process at low energies, we check the influence of the new light vector on kaon decays as well as on the scattering $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{e}^{+}{e}^{-}$ and discuss the impact of the dark Higgs on $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$. Finally, we consider contributions of the V-photon mixing in the decays ${\pi }^0\to \gamma e^{+}{e}^{-}$, $\eta \to \gamma e^{+}{e}^{-}$, $\rho \to \pi e^{+}{e}^{-}$, $K^{\ast }\to K{e}^{+}{e}^{-}$ and $\varphi (1020)\to \eta e^{+}{e}^{-}$.

   hep-phhep-exPRD(2016)·12 citations
7. 07*

   First Monte Carlo analysis of fragmentation functions from single-inclusive $e^{+}{e}^{-}$ annihilation

   N. Sato🇺🇸 · J.J. Ethier🇺🇸 · W. Melnitchouk🇺🇸 · M. Hirai🇯🇵 · S. Kumano🇯🇵 · A. Accardi🇺🇸

   We perform the first iterative Monte Carlo (IMC) analysis of fragmentation functions constrained by all available data from single-inclusive $e^{+}{e}^{-}$ annihilation into pions and kaons. The IMC method eliminates potential bias in traditional analyses based on single fits introduced by fixing parameters not well contrained by the data and provides a statistically rigorous determination of uncertainties. Our analysis reveals specific features of fragmentation functions using the new IMC methodology and those obtained from previous analyses, especially for light quarks and for strange quark fragmentation to kaons.

   hep-phhep-exnucl-thPRD(2016)·92 citations
8. 08*

   Probing CP violation in $h\to {\tau }^{-}{\tau }^{+}$ at the LHC

   Kaoru Hagiwara🇯🇵 · Kai Ma🇨🇳 · Shingo Mori🇯🇵

   We propose a novel method to reconstruct event by event the full kinematics of the cascade decay process, $h\to {\tau }^{+}{\tau }^{-}\to ({\pi }^{+}\bar{\nu })({\pi }^{-}\nu )$, which allows us to measure the ${\tau }^{+}{\tau }^{-}$ spin correlation, a measure of the CP property of the Higgs boson. By noting that the ${\tau }^{\pm }$ momenta lie on the plane spanned by the accurately measured impact parameter and momentum vectors of charged pions, we can obtain the most likely momenta of the two missing neutrinos by using the probability distribution functions of the $\text{met}$ vector and the location of the primary vertex. A simple detector level simulation shows an excellent agreement between the reconstructed and the true kinematics, both in the ${\tau }^{+}{\tau }^{-}$ and the ${\pi }^{+}{\pi }^{-}$ rest frames. The method can be tested in $Z\to {\tau }^{+}{\tau }^{-}$ events, which should exhibit no correlation.

   hep-phhep-exPRL(2017)·32 citations
9. 09*

   Astrophysical constraints on dark-matter $Q$-balls in the presence of baryon-violating operators

   Eric Cotner🇺🇸 · Alexander Kusenko🇯🇵

   Supersymmetric extensions of the standard model predict the existence of non-topological solitons, $Q$-balls. Assuming the standard cosmological history preceded by inflation, $Q$-balls can form in the early universe and can make up the dark matter. The relatively large masses of such dark-matter particles imply a low number density, making direct detection very challenging. The strongest limits come from the existence of neutron stars because, if a baryonic $Q$-ball is captured by a neutron star, the $Q$-ball can absorb the baryon number releasing energy and eventually destroying a neutron star. However, in the presence of baryon number violating higher-dimension operators, the growth of a $Q$-ball inside a neutron star is hampered once the $Q$-ball reaches a certain size. We re-examine the limits and identify some classes of higher-dimensional operators for which supersymmetric $Q$-balls can account for dark matter. The present limits leave a wide range of parameters available for dark matter in the form of supersymmetric $Q$-balls.

   hep-phastro-ph.HEPRD(2016)·25 citations
10. 10*

    Testing Type II Radiative Seesaw Model: from Dark Matter Detection to LHC Signatures

    Shu-Yuan Guo (Nankai U.)🇨🇳 · Zhi-Long Han (Nankai U.)🇨🇳 · Yi Liao (Nankai U., ITP, Beijing, CHEP, Peking U.)🇨🇳

    We analyse the testability of the type II radiative seesaw in which neutrino mass and dark matter (DM) are related at one-loop level. Under the constraints from DM relic density, direct and indirect detection, and invisible Higgs decays, we find three possible regions of DM mass $M_{s_1}$ that can survive the present and even the future experiments: (1) the Higgs resonance region with $M_{s_1}\sim M_h/2$, (2) the Higgs region with $M_{s_1}\sim M_h$, and (3) the coannihilation region with $M_{s_2}\sim M_{s_1}$. Here $s_{1,2}$ are two scalar singlets with the lighter $s_1$ being the DM candidate. Based on DM properties and direct collider constraints, we choose three benchmark points to illustrate the testability of this model at LHC. We perform a detailed simulation of the four-lepton and tri-lepton signatures at 13 (14) TeV LHC. While both signatures are found to be promising at all benchmark points, the tri-lepton one is even better: it is possible to reach the $5\sigma$ significance with an integrated luminosity of 100/fb.

    hep-phPRD(2016)·23 citations
11. 11*

    Nonleptonic decays of $B\to (f_1(1285),f_1(1420))V$ in the perturbative QCD approach

    Xin Liu🇨🇳 · Zhen-Jun Xiao🇨🇳 · Zhi-Tian Zou🇨🇳

    We investigate the branching ratios, the polarization fractions, the direct CP-violating asymmetries, and the relative phases in 20 nonleptonic decay modes of $B\to f_{1}V$ within the framework of perturbative QCD approach at leading order with $f_1$ including two ${}^3{P}_1$-axial-vector states $f_1(1285)$ and $f_1(1420)$. Here, $B$ denotes $B^{+}$, $B^0$, and $B_s^0$ mesons and $V$ stands for the lightest vector mesons $\rho$, $K^{\ast }$, $\omega$, and $\varphi$ , respectively. The $B_s^0\to f_{1}V$ decays are studied theoretically for the first time in the literature. Together with the angle ${\varphi }_{f_1}\approx (24_{-2.7}^{+3.2}{)}^{\circ }$ extracted from the measurement through $B_{d/s}\to J/\psi f_1(1285)$ modes for the $f_1(1285)-f_1(1420)$ mixing system, it is of great interest to find phenomenologically some modes such as the tree-dominated $B^{+}\to f_1{\rho }^{+}$ and the penguin-dominated $B^{+,0}\to f_1{K}^{\ast +,0},B_s^0\to f_1\varphi$ with large branching ratios around $\mathcal{O}(10^{-6})$ or even $\mathcal{O}(10^{-5})$, which are expected measurable at the LHCb and/or the Belle-II experiments in the near future. The good agreement [sharp contrast] of branching ratios and decay pattern for $B^{+}\to f_1{\rho }^{+},B^{+,0}\to f_1(1285)K^{\ast +,0}[B^{+,0}\to f_1(1420)K^{\ast +,0}]$ decays between QCD factorization and perturbative QCD factorization predictions can help us to distinguish these two rather different factorization approaches via precision measurements, which would also be helpful for us to explore the annihilation decay mechanism through its important roles for the considered $B\to f_{1}V$ decays.

    hep-phhep-exPRD(2016)·12 citations
12. 12*

    Structure of charmed baryons studied by pionic decays

    Hideko Nagahiro🇯🇵 · Shigehiro Yasui🇯🇵 · Atsushi Hosaka🇯🇵 · Makoto Oka🇯🇵 · Hiroyuki Noumi🇯🇵

    We investigate the decays of the charmed baryons aiming at the systematic understanding of hadron internal structures based on the quark model by paying attention to heavy quark symmetry. We evaluate the decay widths from the one pion emission for the known excited states, \Lambda_c^*(2595), \Lambda_c^*(2625), \Lambda_c^*(2765), \Lambda_c^*(2880) and \Lambda_c^*(2940), as well as for the ground states \Sigma_c(2455) and \Sigma_c^*(2520). The decay properties of the lower excited charmed baryons are well explained, and several important predictions for higher excited baryons are given. We find that the axial-vector type coupling of the pion to the light quarks is essential, which is expected from chiral symmetry, to reproduce the decay widths especially of the low lying \Lambda_c^* baryons. We emphasize the importance of the branching ratios of \Gamma(\Sigma_c^*\pi)/\Gamma(\Sigma_c\pi) for the study of the nature of higher excited \Lambda_c^* baryons.

    hep-phnucl-thPRD(2017)·91 citations
13. 13*

    Grand unification and CP violation

    Jihn E. Kim🇰🇷

    I will talk on my recent works related to the flavor grand unification, weak CP violation, and the phases in the CKM and PMNS matrices.

    hep-phhep-exPoS(2016)·3 citations
14. 14*

    Factorization, resummation and sum rules for heavy-to-light form factors

    Yu-Ming Wang🇨🇳

    Precision calculations of heavy-to-light form factors are essential to sharpen our understanding towards the strong interaction dynamics of the heavy-quark system and to shed light on a coherent solution of flavor anomalies. We briefly review factorization properties of heavy-to-light form factors in the framework of QCD factorization in the heavy quark limit and discuss the recent progress on the QCD calculation of $B\to \pi$ form factors from the light-cone sum rules with the $B$-meson distribution amplitudes. Demonstration of QCD factorization for the vacuum-to-$B$-meson correlation function used in the sum-rule construction and resummation of large logarithms in the short-distance functions entering the factorization theorem are presented in detail. Phenomenological implications of the newly derived sum rules for $B\to \pi$ form factors are further addressed with a particular attention to the extraction of the CKM matrix element $|V_{ub}|$.

    hep-phEPJ Web Conf.(2016)·1 citation
15. 15*

    Towards the Quantization of Eddington-inspired-Born-Infeld Theory

    Mariam Bouhmadi-López🇵🇹 · Che-Yu Chen🇹🇼

    The quantum effects close to the classical big rip singularity within the Eddington-inspired-Born-Infeld theory (EiBI) are investigated through quantum geometrodynamics. It is the first time that this approach is applied to a modified theory constructed upon Palatini formalism. The Wheeler-DeWitt (WDW) equation is obtained and solved based on an alternative action proposed in Ref.[1], under two different factor ordering choices. This action is dynamically equivalent to the original EiBI action while it is free of square root of the spacetime curvature. We consider a homogeneous, isotropic and spatially flat universe, which is assumed to be dominated by a phantom perfect fluid whose equation of state is a constant. We obtain exact solutions of the WDW equation based on some specific conditions. In more general cases, we propose a qualitative argument with the help of a Wentzel-Kramers-Brillouin (WKB) approximation to get further solutions. Besides, we also construct an effective WDW equation by simply promoting the classical Friedmann equations. We find that for all the approaches considered, the DeWitt condition hinting singularity avoidance is satisfied. Therefore the big rip singularity can be avoided through the quantum approach within the EiBI theory.

    ↳ gr-qchep-phhep-thJCAP(2016)·32 citations
16. 16*

    4D Scattering Amplitudes and Asymptotic Symmetries from 2D CFT

    Clifford Cheung🇺🇸 · Anton de la Fuente🇺🇸 · Raman Sundrum🇺🇸

    We reformulate the scattering amplitudes of 4D flat space gauge theory and gravity in the language of a 2D CFT on the celestial sphere. The resulting CFT structure exhibits an OPE constructed from 4D collinear singularities, as well as infinite-dimensional Kac-Moody and Virasoro algebras encoding the asymptotic symmetries of 4D flat space. We derive these results by recasting 4D dynamics in terms of a convenient foliation of flat space into 3D Euclidean AdS and Lorentzian dS geometries. Tree-level scattering amplitudes take the form of Witten diagrams for a continuum of (A)dS modes, which are in turn equivalent to CFT correlators via the (A)dS/CFT dictionary. The Ward identities for the 2D conserved currents are dual to 4D soft theorems, while the bulk-boundary propagators of massless (A)dS modes are superpositions of the leading and subleading Weinberg soft factors of gauge theory and gravity. In general, the massless (A)dS modes are 3D Chern-Simons gauge fields describing the soft, single helicity sectors of 4D gauge theory and gravity. Consistent with the topological nature of Chern-Simons theory, Aharonov-Bohm effects record the "tracks" of hard particles in the soft radiation, leading to a simple characterization of gauge and gravitational memories. Soft particle exchanges between hard processes define the Kac-Moody level and Virasoro central charge, which are thereby related to the 4D gauge coupling and gravitational strength in units of an infrared cutoff. Finally, we discuss a toy model for black hole horizons via a restriction to the Rindler region.

    ↳ hep-thgr-qchep-phJHEP(2017)·258 citations
17. 17*

    Novel quantum phenomena induced by strong magnetic fields in heavy-ion collisions

    Koichi Hattori🇨🇳 · Xu-Guang Huang🇨🇳

    The relativistic heavy-ion collisions create both hot quark-gluon matter and strong magnetic fields, and provide an arena to study the interplay between quantum chromodynamics and quantum electrodynamics. In recent years, it has been shown that such an interplay can generate a number of interesting quantum phenomena in hadronic and quark-gluon matter. In this short review, we first discuss some properties of the magnetic fields in heavy-ion collisions and then give an overview of the magnetic field-induced novel quantum effects. In particular, we focus on the magnetic effect on the heavy flavor mesons, the heavy-quark transports, and the phenomena closely related to chiral anomaly.

    ↳ nucl-thhep-phnucl-exNucl.Sci.Tech.(2017)·180 citations
18. 18*

    Theoretical study of the Xi(1620) and Xi(1690) resonances in Xi_c -> pi^+ MB decays

    Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵 · Makoto Oka🇯🇵 · Juan Nieves🇪🇸 · Eulogio Oset🇪🇸

    Nonleptonic weak decays of Xi_c into pi^+ and a meson (M)-baryon (B) final state, MB, are analyzed from the viewpoint of probing S=-2 baryon resonances, i.e. Xi(1620) and Xi(1690), of which spin-parity and other properties are not well known. We argue that the weak decay of Xi_c is dominated by a single quark-line diagram, preferred by the Cabibbo-Kobayashi-Maskawa coefficient, color recombination factor, the diquark correlation, and the kinematical condition. The decay process has an advantage of being free from meson resonances in the pi^+M invariant mass distribution. The invariant mass distribution of the meson-baryon final state is calculated with three different chiral unitary approaches, assuming that the Xi(1620) and Xi(1690) resonances have J^P=1/2^-. It is found that a clear peak for the Xi(1690) is seen in the piXi and KbarLambda spectra. We also suggest that the ratios of the piXi, KbarLambda and KbarSigma final states are useful to distinguish whether the peak is originated from the Xi(1690) resonance or it is a KbarSigma threshold effect.

    ↳ nucl-thhep-phPRC(2017)·67 citations
19. 19*

    Gravitational Waves from Primordial Black Holes and New Weak Scale Phenomena

    Hooman Davoudiasl🇺🇸 · Pier Paolo Giardino🇺🇸

    We entertain the possibility that primordialblack holes of mass $\sim (10^{26}$--$10^{29})$~g, with Schwarzschild radii of $\mathcal{O}\text{cm}$, constitute $\sim 10\%$ or more of cosmic dark matter, as allowed by various constraints. These black holes would typically originate from cosmological eras corresponding to temperatures $\mathcal{O}10-100$~GeV, and may be associated with first order phase transitions in the visible or hidden sectors. In case these small primordial black holes get captured in orbits around neutron stars or astrophysical black holes in our galactic neighborhood, gravitational waves from the resulting "David and Goliath (D\&G)" binaries could be detectable at Advanced LIGO or Advanced Virgo for hours or more, possibly over distances of $\mathcal{O}10$~Mpc encompassing the Local Supercluster of galaxies. The proposed Einstein Telescope would further expand the reach for these signals. A positive signal could be further corroborated by the discovery of new particles in the $\mathcal{O}10-100$~GeV mass range, and potentially also the detection of long wavelength gravitational waves originating from the first order phase transition era.

    ↳ gr-qcastro-ph.COhep-phPLB(2017)·6 citations
20. 20*

    Forced canonical thermalization in a hadronic transport approach at high density

    Dmytro Oliinychenko🇺🇦 · Hannah Petersen🇩🇪

    Hadronic transport approaches based on an effective solution of the relativistic Boltzmann equation are widely applied for the dynamical description of heavy ion reactions at low beam energies. At high densities, the assumption of binary interactions often used in hadronic transport approaches may not be applicable anymore. Therefore, we effectively simulate the high-density regime using the local forced canonical thermalization. This framework provides the opportunity to interpolate in a dynamical way between two different limits of kinetic theory: the dilute gas approximation and the ideal fluid case. This approach will be important for studies of the dynamical evolution of heavy ion collisions at low and intermediate energies as experimentally investigated at the beam energy scan program at RHIC, and in the future at FAIR and NICA. On the other hand, this new way of modelling hot and dense strongly-interacting matter might be relevant for small systems at high energies (LHC and RHIC) as well.

    ↳ nucl-thhep-phnucl-exJ.Phys.G(2017)·16 citations
21. 21*

    Prospects for quarkonium measurements in p--A and A--A collisions at the LHC

    Michael Winn🇫🇷

    The potential of the ALICE, ATLAS, CMS and LHCb detectors for the measurement of quarkonium in heavy-ion collisions, both in nucleus-nucleus (A-A) and in proton-nucleus (p-A) interactions, in the years 2015 until about 2030 in the LHC Runs 2, 3 and 4 with larger statistics and detector upgrades is described. A selection of newly available observables is discussed.

    ↳ hep-exhep-phnucl-exFew Body Syst.(2017)·7 citations
22. 22*

    A Compendium of Chameleon Constraints

    Clare Burrage🇬🇧 · Jeremy Sakstein🇺🇸

    The chameleon model is a scalar field theory with a screening mechanism that explains how a cosmologically relevant light scalar can avoid the constraints of intra-solar-system searches for fifth-forces. The chameleon is a popular dark energy candidate and also arises in $f(R)$ theories of gravity. Whilst the chameleon is designed to avoid historical searches for fifth-forces it is not unobservable and much effort has gone into identifying the best observables and experiments to detect it. These results are not always presented for the same models or in the same language, a particular problem when comparing astrophysical and laboratory searches making it difficult to understand what regions of parameter space remain. Here we present combined constraints on the chameleon model from astrophysical and laboratory searches for the first time and identify the remaining windows of parameter space. We discuss the implications for cosmological chameleon searches and future small-scale probes.

    ↳ astro-ph.COgr-qchep-exhep-phJCAP(2016)·135 citations
23. 23*

    Deep inelastic scattering off scalar mesons in the 1/N expansion from the D3D7-brane system

    Nicolas Kovensky🇦🇷 · David Jorrin🇦🇷 · Martin Schvellinger🇦🇷

    Deep inelastic scattering (DIS) of charged leptons off scalar mesons in the $1/N$ expansion is studied by using the gauge/gravity duality. We focus on the D3D7-brane system and investigate the corresponding structure functions by considering both the high energy limit and the $1/N$ expansion. These limits do not commute. From the D7-brane DBI action we derive a Lagrangian at sub-leading order in the D7-brane fluctuations and obtain a number of interactions some of which become relevant for two-hadron final-state DIS. By considering first the high energy limit followed by the large $N$ one, our results fit lattice QCD data within $1.27\%$ for the first three moments of $F_2$ for the lightest pseudoscalar meson.

    ↳ hep-thhep-lathep-phJHEP(2016)·20 citations
24. 24*

    Topology in the SU(Nf) chiral symmetry restored phase of unquenched QCD and axion cosmology

    Vicente Azcoiti🇪🇸

    We investigate the topological properties of unquenched $QCD$ on the basis of numerical results of simulations at fixed topological charge, recently reported by Borsanyi et al.. We demonstrate that their results for the mean value of the chiral condensate at fixed topological charge are inconsistent with the analytical prediction of the large volume expansion around the saddle point, and argue that the most plausible explanation for the failure of the saddle point expansion is a vacuum energy density $\theta$-independent at high temperatures, but surprisingly not too high $(T\sim 2T_c)$, a result which would imply a vanishing topological susceptibility, and the absence of all physical effects of the $U(1)$ axial anomaly at these temperatures. We also show that under a general assumption concerning the high temperature phase of $QCD$, where the $SU(N_f{)}_A$ symmetry is restored, the analytical prediction for the chiral condensate at fixed topological charge is in very good agreement with the numerical results of Borsanyi et al., all effects of the axial anomaly should disappear, the topological susceptibility and all the $\theta$-derivatives of the vacuum energy density vanish and the theory becomes $\theta$-independent at any $T>T_c$ in the infinite volume limit.

    ↳ hep-lathep-phhep-thPRD(2016)·24 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.