Fri·Dec 11, 2015Friday·December 11, 2015

1. 01*

   Shear viscosity over entropy density ratio with extended quasi-particles

   M. Horváth🇭🇺 · A. Jakovác🇭🇺

   We consider an effective field theory description of beyond-quasi-particle excitations aiming to associate the transport properties of the system with the spectral density of states. Tuning various properties of the many-particle correlations, we investigate how the robust microscopic features are translated into the macroscopic observables like shear viscosity and entropy density. The liquid-gas crossover is analysed using several examples. A thermal constraint on the fluidity measure, the ratio of shear viscosity to entropy density, is discussed.

   hep-phhep-thPRD(2016)·4 citations
2. 02*

   The Universal One-Loop Effective Action

   Aleksandra Drozd🇬🇧 · John Ellis🇬🇧 · Jérémie Quevillon🇬🇧 · Tevong You🇬🇧

   We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.

   hep-phhep-thJHEP(2016)·149 citations
3. 03*

   Standard model contribution to the electric dipole moment of the deuteron, ${}^3$H, and ${}^3$He nuclei

   Nodoka Yamanaka🇯🇵 · Emiko Hiyama🇯🇵

   We calculate for the first time the electric dipole moment (EDM) of the deuteron, ${}^3$H, and ${}^3$He nuclei generated by the one-meson exchange CP-odd nuclear force in the standard model. The effective $|\Delta S|=1$ four-quark operators are matched to the $|\Delta S|=1$ standard model processes involving the CP phase of the Cabibbo-Kobayashi-Maskawa matrix at the electroweak scale and run down to the hadronic scale $\mu =1$ GeV according to the renormalization group evolution in the next-to-leading logarithmic order. At the hadronic scale, the hadron matrix elements are modeled in the factorization approach. We then obtain the one-meson (pion, eta meson, and kaon) exchange CP-odd nuclear force, which is the combination of the $|\Delta S|=1$ meson-baryon vertices which issue from the penguin operator and the hyperon-nucleon transition. From this CP-odd nuclear force, the nuclear EDM is calculated with the realistic Argonne $v18$ interaction and the CP-odd nuclear force using the Gaussian expansion method. It is found that the EDMs of light nuclear systems are of order $O(10^{-31})e$ cm. We also estimate the standard model contribution to other hadronic CP violating observables such as the EDMs of ${}^6$Li, ${}^9$Be nuclei, and the atomic EDMs of ${}^{129}$Xe, ${}^{199}$Hg, ${}^{211}$Rn, and ${}^{225}$Ra generated through the nuclear Schiff moment. We then analyze the source of theoretical uncertainties and show some possible ways to overcome them.

   hep-phnucl-thJHEP(2016)·44 citations
4. 04*

   Diboson resonances within a custodially protected warped extra-dimensional scenario

   Andrei Angelescu🇫🇷 · Abdelhak Djouadi🇫🇷 · Grégory Moreau🇫🇷 · François Richard🇫🇷

   We propose an interpretation of the diboson excess recently observed by the ATLAS and CMS collaborations in terms of Kaluza-Klein excitations of electroweak gauge bosons stemming from a realization of a warped extra-dimensional model that is protected by a custodial symmetry. Besides accounting for the LHC diboson data, this scenario also leads to an explanation of the anomalies that have been observed in the measurements of the forward-backward asymmetries for bottom quarks at LEP and top quarks at the Tevatron.

   hep-ph4 citations
5. 05*

   Renormalization group evolution of the universal theories EFT

   James D. Wells🇺🇸 · Zhengkang Zhang🇺🇸

   The conventional oblique parameters analyses of precision electroweak data can be consistently cast in the modern framework of the Standard Model effective field theory (SMEFT) when restrictions are imposed on the SMEFT parameter space so that it describes universal theories. However, the usefulness of such analyses is challenged by the fact that universal theories at the scale of new physics, where they are matched onto the SMEFT, can flow to nonuniversal theories with renormalization group (RG) evolution down to the electroweak scale, where precision observables are measured. The departure from universal theories at the electroweak scale is not arbitrary, but dictated by the universal parameters at the matching scale. But to define oblique parameters, and more generally universal parameters at the electroweak scale that directly map onto observables, additional prescriptions are needed for the treatment of RG-induced nonuniversal effects. We perform a RG analysis of the SMEFT description of universal theories, and discuss the impact of RG on simplified, universal-theories-motivated approaches to fitting precision electroweak and Higgs data.

   hep-phJHEP(2016)·35 citations
6. 06*

   Viability of SUSY-GUT paradigm after LHC

   Marco Chianese🇮🇹

   The SUSY-GUT paradigm is the most promising scenario for the physics beyond the Standard Model. After the LHC run I, it is of interest to reanalyze the room still remaining for SUSY-GUT inspired models and to study the limits on the SUSY mass spectrum. Assuming one step unification of gauge couplings, under some natural requirements we have obtained the energy upper bound for the observation of SUSY phenomenology. We found that in the SUSY-GUT framework the mass of lightest gluino or Higgsino cannot be larger than about 20 TeV.

   hep-phNuovo Cim.C(2016)·0 citations
7. 07*

   ALPtraum: ALP production in proton beam dump experiments

   Babette Döbrich (CERN)🇨🇭 · Joerg Jaeckel (Heidelberg)🇩🇪 · Felix Kahlhoefer (DESY)🇩🇪 · Andreas Ringwald (DESY)🇩🇪 · Kai Schmidt-Hoberg (DESY)🇩🇪

   With their high beam energy and intensity, existing and near-future proton beam dumps provide an excellent opportunity to search for new very weakly coupled particles in the MeV to GeV mass range. One particularly interesting example is a so-called axion-like particle (ALP), i.e. a pseudoscalar coupled to two photons. The challenge in proton beam dumps is to reliably calculate the production of the new particles from the interactions of two composite objects, the proton and the target atoms. In this work we argue that Primakoff production of ALPs proceeds in a momentum range where production rates and angular distributions can be determined to sufficient precision using simple electromagnetic form factors. Reanalysing past proton beam dump experiments for this production channel, we derive novel constraints on the parameter space for ALPs. We show that the NA62 experiment at CERN could probe unexplored parameter space by running in 'dump mode' for a few days and discuss opportunities for future experiments such as SHiP.

   hep-phhep-exJHEP(2016)·268 citations
8. 08*

   Rare Z Decays and Neutrino Flavor Universality

   Gauthier Durieux🇩🇪 · Yuval Grossman🇺🇸 · Matthias König🇩🇪 · Eric Kuflik🇺🇸 · Shamayita Ray🇮🇳

   We study rare four-body decays of the Z-boson involving at least one neutrino and one charged lepton. Large destructive interferences make these decays very sensitive to the Z couplings to neutrinos. As the identified charged leptons can determine the neutrino flavors, these decays probe the universality of the Z couplings to neutrinos. The rare four-body processes could be accurately measured at future lepton colliders, leading to percent level precision.

   hep-phPRD(2016)·3 citations
9. 09*

   Spectra and elliptic flow of charmed hadrons in HYDJET++ model

   G. Eyyubova (SINP, Moscow & Prague, Tech. U.)🇷🇺 · I.P. Lokhtin (SINP, Moscow)🇷🇺 · A.V. Belyaev (SINP, Moscow)🇷🇺 · G. Ponimatkin🇨🇿 · E. Yu. Pronina (SINP, Moscow)🇷🇺

   Heavy-flavour quarks are predominantly produced in hard scatterings on a short time-scale and traverse the medium interacting with its constituents, thus they are one of the effective probes of the transport properties of the medium formed in relativistic heavy ion collisions. On the other hand, the thermal production of heavy-flavour quarks in quark-gluon plasma (QGP) is itself of interest. In this report, the production and elliptic flow of the prompt charmed mesons $D^0$, $D^{+}$, $D^{\ast +}$ and $J/\psi$ in PbPb collisions at the center-of-mass energy 2.76 TeV per nucleon pair are described in the framework of two-component HYDJET++ model. The model combines thermal and pQCD production mechanisms. The spectra and elliptic flow of charmed mesons are presented, the results are compared with LHC data.

   hep-phnucl-thPoS(2015)·0 citations
10. 10*

    Decipher the short-distance component of $X(3872)$ in $B_c$ decays

    Wei Wang🇨🇳 · Qiang Zhao🇨🇳

    A foremost task in understanding the nature of the $X(3872)$ involves the discrimination of the two-quark and multiquark configurations. In this work, we propose a method to probe the short-distance component of the $X(3872)$ by measuring the ratio between the $B_c$ semileptonic and nonleptonic decays into the $X(3872)$. We demonstrate that if the $X(3872)$ production mechanism is through the $\bar{c}c$ component, the ratios would be universal and could be reliably predicted in theory. Measurements of these ratios at LHC and the next-generation electron-positron colliders are capable of validating/invalidating this production mechanism and providing deeper insights into the nature of the $X(3872)$.

    hep-phhep-exPLB(2016)·22 citations
11. 11*

    Compositeness of Hadron Resonances and Quasi-Bound States

    Tetsuo Hyodo🇯🇵

    We discuss the composite nature of hadrons appearing near the s-wave two-hadron threshold. Generalizing the Weinberg's weak-binding relation for stable bound states, we show that the compositeness of near-threshold resonances and quasi-bound states can be determined by observable quantities.

    hep-phnucl-thJPS Conf.Proc.(2017)·0 citations
12. 12*

    Understanding the Nature of $\Lambda (1405)$ through Regge Physics

    Cesar Fernandez-Ramirez🇲🇽 · Igor V. Danilkin🇩🇪 · Vincent Mathieu🇺🇸 · Adam P. Szczepaniak🇺🇸

    It appears that there are two resonances with $J^P=1/2^{-}$ quantum numbers in the energy region near the $\Lambda (1405)$ hyperon. The nature of these states is a topic of current debate. To provide further insight we use Regge phenomenology to access how these two resonances fit the established hyperon spectrum. We find that only one of these resonances is compatible with a three-quark state.

    hep-phnucl-thPRD(2016)·36 citations
13. 13*

    Intersecting Branes, SUSY Breaking and the 2TeV Excess at the LHC

    Ralph Blumenhagen🇩🇪

    Intersecting D-brane models in string theory can naturally support the gauge and matter content of left-right symmetric extensions of the Standard Model with gauge symmetry SU(3)_c x SU(2)_L x SU(2)_R x U(1)_{B-L}. Considering such models as candidates for explaining the 2TeV excesses seen in Run-1 by both ATLAS and CMS, the minimal possible scale of supersymmetry breaking is determined by the requirement of precise one-loop gauge coupling unification. For the vector-like, bifundamental and (anti-)symmetric Higgs content of such brane configurations, this comes out fairly universally at around 19TeV. For the SU(2)_R gauge coupling one finds values 0.48<g_R(M_R)<0.6. Threshold corrections can potentially lower the scale of supersymmetry breaking.

    hep-phhep-thJHEP(2016)·10 citations
14. 14*

    Polynomial Spectrum of Gamma Ray from Dark Matter

    Yong Tang (KIAS)🇰🇷

    In this study, we present some general features of gamma-ray spectra from dark matter. We find that the spectrum with sharp features could appear in a wide class of dark matter models and mimic the gamma line signals. If all other physical degrees of freedom are heavy or effectively decoupled, the resulting gamma ray from dark matter decay or annihilation would generally have polynomial-type spectra or power-law with positive index. We illustrate our findings in a model-independent framework with generic kinematic analysis. Similar results can also apply for cosmic ray or neutrino cases.

    hep-phastro-ph.COastro-ph.HEInt.J.Mod.Phys.A(2017)·4 citations
15. 15*

    Constraints on the $U(1{)}_L$ gauge boson in a wide mass range

    Yu Seon Jeong🇰🇷 · C. S. Kim🇰🇷 · Hye-Sung Lee🇨🇭

    There is a growing interest for the search of new light gauge bosons. The small mass of a new boson can turn various kinds of low-energy experiments to a new discovery machine, depending on their couplings to the standard model particles. It is important to understand the properties of each type of gauge boson and their current constraints for a given mass. While the dark photon (which couples to the electric charges) and the $U(1{)}_{B-L}$ gauge boson have been well studied in an extensive mass range, the $U(1{)}_L$ gauge boson has not been fully investigated yet. We consider the gauge boson of the $U(1{)}_L$ in a wide mass range $m_{Z^{\prime }}\approx 0-10^{12}\text{ev}$ and investigate the constraints on its coupling from various experiments, discussing the similarities and differences from the dark photon and the $U(1{)}_{B-L}$ gauge boson.

    hep-phInt.J.Mod.Phys.A(2016)·32 citations
16. 16*

    Composite Higgs Models, Technicolor and The Muon Anomalous Magnetic Moment

    A. Doff🇧🇷 · Clarissa Siqueira🇧🇷

    We revisit the muon magnetic moment (g-2) in the context of Composite Higgs models and Technicolor, and provide general analytical expressions for computing the muon magnetic moment stemming from new fields such as, neutral gauge bosons, charged gauge bosons, neutral scalar, charged scalars, and exotic charged leptons type of particles. Under general assumptions we assess which particle content could address the $g-2_{\mu }$ excess. Moreover, we take a conservative approach and derive stringent limits on the particle masses in case the anomaly is otherwise resolved and comment on electroweak and collider bounds. Lastly, for concreteness we apply our results to a particular Technicolor model.

    hep-phPLB(2016)·10 citations
17. 17*

    Lepton flavor violating decays of Standard-Model-like Higgs in 3-3-1 model with neutral lepton

    L. T. Hue🇻🇳 · H. N. Long🇻🇳 · T. T. Thuc🇻🇳 · T. Phong Nguyen🇻🇳

    The one loop contribution to the lepton flavor violating decay $h^0\to \mu \tau$ of the SM-like neutral Higgs (LFVHD) in the 3-3-1 model with neutral lepton is calculated using the unitary gauge. We have checked in detail that the total contribution is exactly finite, and the divergent cancellations happen separately in two parts of active neutrinos and exotic heavy leptons. By numerical investigation, we have indicated that the one-loop contribution of the active neutrinos is very suppressed while that of exotic leptons is rather large. The branching ratio of the LFVHD strongly depends on the Yukawa couplings between exotic leptons and $SU(3{)}_L$ Higgs triplets. This ratio can reach $10^{-5}$ providing large Yukawa couplings and constructive correlations of the $SU(3{)}_L$ scale ($v_3$) and the charged Higgs masses. The branching ratio decreases rapidly with the small Yukawa couplings and large $v_3$.

    hep-phNPB(2016)·55 citations
18. 18*

    Nuclear Parton Distributions and the Drell-Yan Reaction

    S.A. Kulagin🇷🇺 · R. Petti🇺🇸

    We discuss the nuclear parton distribution functions on the basis of our recently developed semi-microscopic model, which takes into account a number of nuclear effects including Fermi motion and nuclear binding, nuclear meson-exchange currents and off-shell corrections to bound nucleon distributions as well as nuclear shadowing effect. We also discuss application to the nuclear Drell-Yan process and compare our predictions with data from the E772 and E866 experiments.

    hep-phPoS(2015)·2 citations
19. 19*

    Some theoretical and experimental aspects of axion physics

    Albert Renau🇪🇸

    In the first part of the thesis, we revisit the Dine-Fischler-Srednicki-Zhitnisky axion model in light of the recent Higgs LHC results and electroweak precision data. This model is an extension of the two-Higgs-doublet model incorporating a PQ symmetry which leads to a physically acceptable axion. For generic values of the couplings, the model reproduces the minimal Standard Model, with a massless axion and all the other degrees of freedom at a very high scale. However, in some scenarios, the extra Higgses could be relatively light. We use the oblique corrections, in particular $\Delta \rho$, to constrain the mass spectrum in this case. Finally, we also work out the non-linear parametrization of the DFSZ model in the generic case where all scalars except the lightest Higgs and the axion have masses at or beyond the TeV scale. In the second part, we study the relevance of a cold axion background (CAB) as a responsible for the dark matter in the Universe and examine its consequences through its effects on photon and cosmic ray propagation. We study the axion-photon system under the joint influence of two backgrounds: an external magnetic field and a CAB. Their effect consists in producing a three-way mixing of the axion with the two polarizations of the photon. We determine the proper frequencies and eigenvectors as well as the corresponding photon ellipticity and induced rotation of the polarization plane that depend both on the magnetic field and the local density of axions. We also comment on the possibility that some of the predicted effects could be measured in optical table-top experiments. Circularly polarized photons are energy eigenstates, with a modified dispersion relation. This enables the emission of a photon by a charged particle, which is forbidden in regular QED. We study the energy loss of a cosmic ray due and compute the energy flux of photons emitted in this way.

    hep-ph3 citations
20. 20*

    Pinning down inelastic dark matter in the Sun and in direct detection

    Mattias Blennow🇸🇪 · Stefan Clementz🇸🇪 · Juan Herrero-Garcia🇸🇪

    We study the solar capture rate of inelastic dark matter with endothermic and/or exothermic interactions. By assuming that an inelastic dark matter signal will be observed in next generation direct detection experiments we can set a lower bound on the capture rate that is independent of the local dark matter density, the velocity distribution, the galactic escape velocity as well as the scattering cross section. In combination with upper limits from neutrino observatories we can place upper bounds on the annihilation channels leading to neutrinos. We find that, while endothermic scattering limits are weak in the isospin-conserving case, strong bounds may be set for exothermic interactions, in particular in the spin-dependent case. Furthermore, we study the implications of observing two direct detection signals, in which case one can halo-independently obtain the dark matter mass and the mass splitting, and disentangle the endothermic/exothermic nature of the scattering. Finally we discuss isospin violation.

    hep-phastro-ph.COJCAP(2016)·41 citations
21. 21*

    Phenomenology of left-right symmetric dark matter

    Camilo Garcia-Cely🇧🇪 · Julian Heeck🇧🇪

    We present a detailed study of dark matter phenomenology in low-scale left-right symmetric models. Stability of new fermion or scalar multiplets is ensured by an accidental matter parity that survives the spontaneous symmetry breaking of the gauge group by scalar triplets. The relic abundance of these particles is set by gauge interactions and gives rise to dark matter candidates with masses above the electroweak scale. Dark matter annihilations are thus modified by the Sommerfeld effect, not only in the early Universe, but also today, for instance, in the Center of the Galaxy. Majorana candidates - triplet, quintuplet, bi-doublet, and bi-triplet - bring only one new parameter to the model, their mass, and are hence highly testable at colliders and through astrophysical observations. Scalar candidates - doublet and 7-plet, the latter being only stable at the renormalizable level - have additional scalar-scalar interactions that give rise to rich phenomenology. The particles under discussion share many features with the well-known candidates wino, Higgsino, inert doublet scalar, sneutrino, and Minimal Dark Matter. In particular, they all predict a large gamma-ray flux from dark matter annihilations, which can be searched for with Cherenkov telescopes. We furthermore discuss models with unequal left-right gauge couplings, $g_R\ne g_L$, taking the recent experimental hints for a charged gauge boson with 2 TeV mass as a benchmark point. In this case, the dark matter mass is determined by the observed relic density.

    hep-phastro-ph.HEhep-exJCAP(2016)·65 citations
22. 22*

    Constraining top quark effective theory in the LHC Run II era

    Andy Buckley🇬🇧 · Christoph Englert🇬🇧 · James Ferrando🇬🇧 · David J. Miller🇬🇧 · Liam Moore🇬🇧 · Michael Russell🇬🇧 · Chris D. White🇬🇧

    We perform an up-to-date global fit of top quark effective theory to experimental data from the Tevatron, and from LHC Runs I and II. Experimental data includes total cross-sections up to 13 TeV, as well as differential distributions, for both single top and pair production. We also include the top quark width, charge asymmetries, and polarisation information from top decay products. We present bounds on the coefficients of dimension six operators, and examine the interplay between inclusive and differential measurements, and Tevatron / LHC data. All results are currently in good agreement with the Standard Model.

    hep-phhep-exJHEP(2016)·263 citations
23. 23*

    Multi-Regge kinematics and azimuthal angle observables for inclusive four-jet production

    F. Caporale🇪🇸 · Francesco Giovanni Celiberto🇮🇹 · G. Chachamis🇪🇸 · A. Sabio Vera🇪🇸

    We evaluate differential cross sections for production of four jets in multi-Regge kinematics at a hadron collider. The main focus lies on azimuthal angle dependences. As in previous studies, the ratios of correlation functions of products of cosines of azimuthal angle differences among the tagged jets offer us the cleanest quantities to compare with experimental data. The calculations are based on the jet production from a single BFKL ladder with a convolution of three BFKL Green functions where we always have two forward/backward jets tagged in the final state. We also demand the tagging of two further jets in more central regions of the detectors with a relative separation in rapidity from each other, plus the inclusive production of an arbitrary number of mini-jets. We show that dependences on the transverse momenta and rapidity of the two central jets can be a distinct signal of the onset of BFKL dynamics.

    hep-phEPJC(2016)·89 citations
24. 24*

    Helicity Asymmetry Measurement for ${\pi }^0$ Photoproduction on the CLAS Frozen Spin Target

    Diane Schott🇺🇸 · William Briscoe🇺🇸 · Igor Strakovsky (GWU)🇺🇸

    The measurement was performed with circularly polarized photons incident on longitudinally polarized target in Hall B at the Thomas Jefferson National Accelerator Facility. The helicity asymmetry E for $\vec{\gamma }\vec{p}\to {\pi }^{0}p$ was determined at CM energies between 1450 MeV and 2050 MeV and compared to the SAID, MAID, and BnGa partial-wave analyses.

    ↳ nucl-exhep-exhep-phnucl-thAIP Conf.Proc.(2016)·2 citations
25. 25*

    Canonical single field slow-roll inflation with a non-monotonic tensor-to-scalar ratio

    Gabriel German🇲🇽 · Alfredo Herrera-Aguilar🇲🇽 · Juan Carlos Hidalgo🇲🇽 · Roberto A. Sussman🇲🇽

    We take a pragmatic, model independent approach to single field slow-roll canonical inflation by imposing conditions, not on the potential, but on the slow-roll parameter $ϵ(\varphi )$ and its derivatives ${ϵ}^{\prime }(\varphi )$ and ${ϵ}^{\prime \prime }(\varphi )$, thereby extracting general conditions on the tensor-to-scalar ratio $r$ and the running $n_{sk}$ at ${\varphi }_H$ where the perturbations are produced, some $50$ $-$ $60$ $e$-folds before the end of inflation. We find quite generally that for models where $ϵ(\varphi )$ develops a maximum, a relatively large $r$ is most likely accompanied by a positive running while a negligible tensor-to-scalar ratio implies negative running. The definitive answer, however, is given in terms of the slow-roll parameter ${\xi }_2(\varphi )$. To accommodate a large tensor-to-scalar ratio that meets the limiting values allowed by the Planck data, we study a non-monotonic $ϵ(\varphi )$ decreasing during most part of inflation. Since at ${\varphi }_H$ the slow-roll parameter $ϵ(\varphi )$ is increasing, we thus require that $ϵ(\varphi )$ develops a maximum for $\varphi >{\varphi }_H$ after which $ϵ(\varphi )$ decrease to small values where most $e$-folds are produced. The end of inflation might occur trough a hybrid mechanism and a small field excursion $\Delta {\varphi }_e\equiv |{\varphi }_H-{\varphi }_e|$ is obtained with a sufficiently thin profile for $ϵ(\varphi )$ which, however, should not conflict with the second slow-roll parameter $\eta (\varphi )$. As a consequence of this analysis we find bounds for $\Delta {\varphi }_e$, $r_H$ and for the scalar spectral index $n_{sH}$. Finally we provide examples where these considerations are explicitly realised.

    ↳ astro-ph.COgr-qchep-phJCAP(2016)·7 citations
26. 26*

    Probing short-range nucleon-nucleon interactions with an Electron-Ion Collider

    Gerald A. Miller🇺🇸 · Matthew D. Sievert🇺🇸 · Raju Venugopalan🇺🇸

    We derive the cross-section for exclusive vector meson production in high energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross-section can be expressed in terms of a novel gluon Transition Generalized Parton Distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial and final state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: in particular, we discuss the relative role of "point-like" and "geometric" Fock configurations that control the parton dynamics of short range nucleon-nucleon scattering. With the aid of exclusive $J/\Psi$ production data at HERA, as well as elastic nucleon-nucleon cross-sections, we estimate rates for exclusive deuteron photo-disintegration at a future Electron-Ion Collider (EIC). Our results, obtained using conservative estimates of EIC integrated luminosities, suggest that center-of-mass energies $s_{NN}\sim 12$ GeV${}^2$ of the neutron-proton subsystem can be accessed. We argue that the high energies of the EIC can address outstanding dynamical questions regarding the short-range quark-gluon structure of nuclear forces by providing clean gluon probes of such "knockout" exclusive reactions in light and heavy nuclei.

    ↳ nucl-thhep-phnucl-exPRC(2016)·11 citations
27. 27*

    Vacuum and Gravitons of Relic Gravitational Waves, and Regularization of Spectrum and Energy-Momentum Tensor

    Dong-Gang Wang🇨🇳 · Yang Zhang🇨🇳 · Jie-Wen Chen🇨🇳

    The spectrum of relic gravitational wave (RGW) contains high-frequency divergences, which should be removed. We present a systematic study of the issue, based on the exact RGW solution that covers the five stages, from inflation to the acceleration, each being a power law expansion. We show that the present RGW consists of vacuum dominating at $f>10^{11}$Hz and graviton dominating at $f<10^{11}$Hz, respectively. The gravitons are produced by the four cosmic transitions, mostly by the inflation-reheating one. We perform adiabatic regularization to remove vacuum divergences in three schemes: at present, at the end of inflation, and at horizon-exit, to the 2-nd adiabatic order for the spectrum, and the 4-th order for energy density and pressure. In the first scheme a cutoff is needed to remove graviton divergences. We find that all three schemes yield the spectra of a similar profile, and the primordial spectrum defined far outside horizon during inflation is practically unaffected. We also regularize the gauge-invariant perturbed inflaton and the scalar curvature perturbation by the last two schemes, and find that the scalar spectra, the tensor-to-scalar ratio, and the consistency relation remain unchanged.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2016)·32 citations
28. 28*

    Formation spectra of charmed meson--nucleus systems using an antiproton beam

    J. Yamagata-Sekihara🇯🇵 · C. Garcia-Recio🇪🇸 · J. Nieves🇪🇸 · L.L. Salcedo🇪🇸 · L. Tolos🇩🇪

    We investigate the structure and formation of charmed meson--nucleus systems, with the aim of understanding the charmed meson--nucleon interactions and the properties of the charmed mesons in the nuclear medium. The $\bar{D}$ mesic nuclei are of special interest, since they have tiny decay widths due to the absence of strong decays for the $\bar{D}N$ pair. Employing an effective model for the $\bar{D}N$ and $DN$ interactions and solving the Klein--Gordon equation for $\bar{D}$ and $D$ in finite nuclei, we find that the $D^{-}$-${}^{11}\mathrm{B}$ system has $1s$ and $2p$ mesic nuclear states and that the $D^0$-${}^{11}\mathrm{B}$ system binds in a $1s$ state. In view of the forthcoming experiments by the PANDA and CBM Collaborations at the future FAIR facility and the J-PARC upgrade, we calculate the formation spectra of the $[D^{-}$-${}^{11}\mathrm{B}]$ and $[D^0$-${}^{11}\mathrm{B}]$ mesic nuclei for an antiproton beam on a ${}^{12}\mathrm{C}$ target. Our results suggest that it is possible to observe the $2p$ $D^{-}$ mesic nuclear state with an appropriate experimental setup.

    ↳ nucl-thhep-phPLB(2016)·15 citations
29. 29*

    New results on the XYZ states from Belle experiment

    Chang-Zheng Yuan (for the Belle Collaboration)🇨🇳

    We review the results on the XYZ states from the Belle experiment, including the measurement of inclusive hadronic cross sections and exclusive cross sections in e+e- annihilation and the Z_b states in the bottomonium energy region; and the study of the Y states and the Z_c states in charmonium energy region.

    ↳ hep-exhep-phAIP Conf.Proc.(2016)·2 citations
30. 30*

    Studies of Hadron Structure and Interactions with the $\overline{\mathbf{P}}$ANDA Experiment at FAIR

    PANDA Collaboration · Nora Brambilla · Ulf-G. Meißner

    The $\overline{\text{mbox}P}$ANDA experiment together with the high quality antiproton beam at HESR will be a powerful tool to address fundamental questions of hadron physics in the charm and multi-strange hadron sector. In connection with the recent data in the hidden charm sector, $\overline{\text{mbox}P}$ANDA will be able to deliver decisive contributions to this field, due to the complementarity of the $\overline{p}p$ entrance channel and the capabilities of the combined storage ring and detector system under construction.

    ↳ hep-exhep-ph1 citation
31. 31*

    New soft theorems for the gravity dilaton and the Nambu-Goldstone dilaton at subsubleading order

    Paolo Di Vecchia🇩🇰 · Raffaele Marotta🇮🇹 · Matin Mojaza🇸🇪 · Josh Nohle🇺🇸

    We study the soft behavior of two seemingly different particles that are both referred to as dilatons in the literature, namely the one that appears in theories of gravity and in string theory and the Nambu-Goldstone boson of spontaneously broken conformal invariance. Our primary result is the discovery of a soft theorem at subsubleading order for each dilaton, which in both cases contains the operator of special conformal transformations. Interesting similarities as well as differences between the dilaton soft theorems are discussed.

    ↳ hep-thhep-phPRD(2016)·78 citations

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