Tue·Feb 27, 2018Tuesday·February 27, 2018

1. 01*

   How can $X^{\pm }(5568)$ escape detection?

   Hong-Wei Ke🇺🇸 · Xue-Qian Li🇨🇳

   Multi-quark states were predicted by Gell-Mann when the quark model was first formulated. Recently, numerous exotic states that are considered to be multi-quark states have been experimentally confirmed (four-quark mesons and five-quark baryons). Theoretical research indicates that the four-quark state might comprise molecular and/or tetraquark structures. We consider that the meson containing four different flavors $su\bar{b}\bar{d}$ should exist and decay via the $X(5568)\to B_s\pi$ channel. However, except for the D0 collaboration, all other experimental collaborations have reported negative observations for $X(5568)$ in this golden portal. This contradiction has stimulated the interest of both theorists and experimentalists. To address this discrepancy, we propose that the assumed $X(5568)$ is a mixture of a molecular state and tetraquark, which contributes destructively to $X(5568)\to B_s\pi$. The cancellation may be accidental and it should be incomplete. In this scenario, there should be two physical states with the same flavor ingredients, with spectra of $5344\pm 307$ and $6318\pm 315$. $X(5568)$ lies in the error range of the first state. We predict the width of the second state (designated as $S_2$) as $\Gamma (X_{S_2}\to B_s\pi )=224\pm 97$ MeV. We strongly suggest searching for it in future experiments.

   hep-phhep-exPLB(2018)·8 citations
2. 02*

   Search for $thj$ production with $h\to \gamma \gamma$ at the LHC in the littlest Higgs model with T-parity

   Bingfang Yang🇨🇳 · Biaofeng Hou🇨🇳 · Huaying Zhang🇨🇳

   In the littlest Higgs model with T-parity, we study associated production of a Higgs and a single top quark at the 14 TeV LHC. We focus on the Higgs to two photons decay and the semileptonic top decay channel. By performing a fast detector simulation, we find that the $thj$ search in the selected channel can excluded the top partner mass $m_{T_{+}}$ up to 805 (857) GeV for case A (case B) at $2\sigma$ confidence level at 14 TeV LHC with the integrated luminosity $L=3\mathrm{a}{\mathrm{b}}^{-1}$.

   hep-phNPB(2018)·5 citations
3. 03*

   Branching ratios and $CP$ asymmetries of $B\to {\chi }_{c1}K(\pi )$ decays

   Zhou Rui🇨🇳 · Qiang Zhao🇨🇳 · Li-li Zhang🇨🇳

   We investigate the exclusive nonleptonic decays $B\to {\chi }_{c1}K(\pi )$ in the conventional perturbative QCD (PQCD) formalism. The predictions of branching ratios and $CP$ asymmetries are given in detail. We compare our results with available experimental data as well as predictions of other theoretical studies existing in the literature. It seems that the branching ratios of $B\to {\chi }_{c1}K$ are more consistent with data than the earlier analyses. For the Cabibbo-suppressed $B_s$ decay, the branching ratio can reach the order of $10^{-5}$, which would be straight forward for experimental observations. The numerical results show that the direct $CP$ asymmetries of the concerned decays are rather small. The mixing-induced $CP$ asymmetry in the $B^0\to {\chi }_{c1}{K}_S$ is very close to $\sin 2\beta$, which suggests that this channel offer an alternative method for measuring the Cabbibo-Kobayashi-Maskawa (CKM) angle $\beta$. The obtained results in the present work could be tested by further experiments in the LHCb and forthcoming Belle II.

   hep-phEPJC(2018)·4 citations
4. 04*

   On tetraquarks with hidden charm and strangeness as phi-psi(2S) hadrocharmonium

   Julia Yu. Panteleeva🇷🇺 · Irina A. Perevalova🇷🇺 · Maxim V. Polyakov🇷🇺 · Peter Schweitzer🇺🇸

   In the hadrocharmonium picture a $\bar{c}c$ state and a light hadron form a bound state. The effective interaction is described in terms of the chromoelectric polarizability of the $\bar{c}c$ state and energy-momentum-tensor densities of the light hadron. This picture is justified in the heavy quark limit, and may successfully account for a hidden-charm pentaquark state recently observed by LHCb. In this work we extend the formalism to the description of hidden-charm tetraquarks, and address the question of whether the resonant states observed by LHCb in the $J/\psi$-$\varphi$ spectrum can be described as hadrocharmonia. This is a non-trivial question because nothing is known about the $\varphi$ meson energy-momentum-tensor densities. With rather general assumptions about energy-momentum-tensor densities in the $\varphi$-meson we show that a $\psi (2S)$-$\varphi$ bound state can exist, and obtain a characteristic relation between its mass and width. We show that the tetraquark $X(4274)$ observed by LHCb in $J/\psi$-$\varphi$ spectrum is a good candidate for a hadrocharmonium. We make predictions which will allow testing this picture. Our method can be generalized to identify other potential hadrocharmonia.

   hep-phPRC(2019)·20 citations
5. 05*

   Wrong Sign Bottom Yukawa in Low Energy Supersymmetry

   Nina M. Coyle🇺🇸 · Bing Li🇺🇸 · Carlos E. M. Wagner🇺🇸

   The study of the Higgs boson properties is one of the most relevant activities in current particle physics. In particular, the Higgs boson couplings to third generation fermions is an important test of the mechanism of mass generation. In spite of their impact on the production and decay properties of the Higgs boson, the values of these couplings are still uncertain and, in models of new physics, they can differ in magnitude as well as in sign with respect to the Standard Model case. In this article, we study the possibility of a wrong sign bottom-quark Yukawa coupling within the framework of the Minimal and Next-to-Minimal Supersymmetric Standard Model. Possible experimental tests are also discussed, including novel decays of the heavy CP-even and CP-odd Higgs fields that may be probed in the near future and that may lead to an explanation of some intriguing di-boson signatures observed at the ATLAS experiment.

   hep-phPRD(2018)·18 citations
6. 06*

   A novel demonstration of the renormalization group invariance of the fixed-order predictions using the principle of maximum conformality and the $C$-scheme coupling

   Xing-Gang Wu🇨🇳 · Jian-Ming Shen🇨🇳 · Bo-Lun Du🇨🇳 · Stanley J. Brodsky🇺🇸

   As a basic requirement of the renormalization group invariance, any physical observable must be independent of the choice of both the renormalization scheme and the initial renormalization scale. In this paper, we show that by using the newly suggested $C$-scheme coupling, one can obtain a demonstration that the {\it Principle of Maximum Conformality} prediction is scheme-independent to all-orders for any renormalization schemes, thus satisfying all of the conditions of the renormalization group invariance. We illustrate these features for the non-singlet Adler function and for $\tau$ decay to $\nu +$ hadrons at the four-loop level.

   hep-phPRD(2018)·47 citations
7. 07*

   New physics with the lepton flavor violating decay $\tau \to 3\mu$

   Zaineb Calcuttawala🇮🇳 · Anirban Kundu🇮🇳 · Soumitra Nandi🇮🇳 · Sunando Kumar Patra🇮🇳

   Lepton flavour violating (LFV) processes are a smoking gun signal of new physics (NP). If the semileptonic $B$ decay anomalies are indeed due to some NP, such operators can potentially lead to LFV decays involving the second and the third generation leptons, like $\tau \to 3\mu$. In this paper, we explore how far the nature of NP can be unraveled at the next generation $B$-factories like Belle-II, provided the decay $\tau \to 3\mu$ has been observed. We use four observables with which the differentiation among NP operators may be achieved to a high confidence level. Possible presence of multiple NP operators are also analysed with the Optimal Observable technique. While the analysis can be improved even further if the final state muon polarisations are measured, we present this work as a motivational tool for the experimentalists, as well as a template for the analysis of similar processes.

   hep-phPRD(2018)·15 citations
8. 08*

   Phenomenology of the Higgs sector of a Dimension-7 Neutrino Mass Generation Mechanism

   Tathagata Ghosh🇺🇸 · Sudip Jana🇺🇸 · S. Nandi🇺🇸

   In this paper, we revisit the dimension-7 neutrino mass generation mechanism based on the addition of an isospin $3/2$ scalar quadruplet and two vector-like iso-triplet leptons to the standard model. We discuss the LHC phenomenology of the charged scalars of this model, complemented by the electroweak precision and lepton flavor violation constraints. We pay particular attention to the triply charged and doubly charged components. We focus on the same-sign-tri-lepton signatures originating from the triply-charged scalars and find a discovery reach of 600 - 950 GeV at 3 ab${}^{-1}$ of integrated luminosity at the LHC. On the other hand, doubly charged Higgs has been an object of collider searches for a long time, and we show how the present bounds on its mass depend on the particle spectrum of the theory. Strong constraint on the model parameter space can arise from the measured decay rate of the Standard Model Higgs to a pair of photons as well.

   hep-phPRD(2018)·30 citations
9. 09*

   Mass measurable phase differences in neutrino oscillations

   Xiang Zhou🇨🇳

   We propose an ansatz, named the "particle ansatz", that in the rest frame of a flavor neutrino all its mass eigenstate momentums should simultaneously be zero. Under the particle ansatz, the mass measurable phase differences (mmPhDs) can be derived as $\Delta {\varphi }_{ji}\simeq [2m_{{\nu }_{\alpha }}(m_j-m_i)/4E_{{\nu }_{\alpha }}]L$. We show that using mmPhDs all three neutrino masses can be determined. In the foreseeable future all neutrino masses are expected to be determined by the spectral analysis of neutrino experiments.

   hep-phastro-ph.CO1 citation
10. 10*

    Multi Phase in Cold Dense Quark Matter

    Song Shi · Juan Liu · Zhu-fang Cui

    In this article, we study dynamic chiral symmetry breaking at zero temperature, finite chemical potential and external magnetic field with massless NJL model. We have proposed a mathematical method to classify phases in phase diagram of cold dense quark matter, and use mathematical analysis to identify the multi phase phenomenon among solutions for gap equation which means with fixed chemical potential and magnetic field, there could be two phases coexisting.

    hep-phhep-th0 citations
11. 11*

    Vector Meson Photoproduction with a Linearly Polarized Beam

    JPAC Collaboration: V. Mathieu🇺🇸 · J. Nys🇧🇪 · C. Fernández-Ramírez🇲🇽 · A. Jackura🇺🇸 · A. Pilloni🇺🇸 · N. Sherrill🇺🇸 · A. Szczepaniak🇺🇸 · G. Fox🇺🇸

    We propose a model based on Regge theory to describe photoproduction of light vector mesons. We fit the SLAC data and make predictions for the energy and momentum transfer dependence of the spin-density matrix elements in photoproduction of $\omega$, ${\rho }^0$ and $\varphi$ mesons at $E_{\gamma }\sim 8.5$ GeV, which are soon to be measured at Jefferson Lab.

    hep-phPRD(2018)·36 citations
12. 12*

    Model independent New Physics analysis in ${\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-}$ decay

    Diganta Das🇮🇳

    We study the rare ${\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-}$ decay in the Standard Model and beyond. Beyond the Standard Model we include new vector and axial-vector operators, scalar and pseudo-scalar operators, and tensor operators in the effective Hamiltonian. Working in the helicity basis and using appropriate parametrization of the ${\Lambda }_b\to \Lambda$ hadronic matrix elements, we give expressions of hadronic and leptonic helicity amplitudes and derive expression of double differential branching ratio with respect to dilepton invariant mass squared and cosine of lepton angle. Appropriately integrating the differential branching ratio over the lepton angle, we obtain the longitudinal polarization fraction and the leptonic forward-backward asymmetry and sequentially study the observables in the presence of the new couplings. To analyze the implications of the new vector and axial-vector couplings, we follow the current global fits to $b\to s{\mu }^{+}{\mu }^{-}$ data. While the impacts of scalar couplings can be significant, exclusive $\bar{B}\to X_s{\mu }^{+}{\mu }^{-}$ data imply stringent constraints on the tensor couplings and hence the effects on ${\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-}$ are negligible.

    hep-phEPJC(2018)·49 citations
13. 13*

    Reparametrization Invariance and Partial Re-Summations of the Heavy Quark Expansion

    Thomas Mannel🇩🇪 · K. Keri Vos🇩🇪

    We extend existing work on reparametrization invariance (RPI) of the heavy-quark expansion. We discuss the total rates of inclusive processes and obtain results which have a manifest RPI and can be expressed through matrix elements of operators and states defined in full QCD. This approach leads to a partial re-summation of higher-order terms in the heavy-quark expansion and has the advantage that the number of independent parameters is reduced.

    hep-phhep-thJHEP(2018)·47 citations
14. 14*

    Naturally light scalar particles: a generic and simple mechanism

    F. Léonard🇫🇷 · B. Delamotte🇫🇷 · N. Wschebor🇺🇾

    The hierarchy problem in the Standard Model is usually understood as both a technical problem of stability of the calculation of the quantum corrections to the masses of the Higgs sector and of the unnatural difference between the Planck and gauge breaking scales. Leaving aside the gauge sector, we implement on a purely scalar model a mechanism for generating naturally light scalar particles where both of these issues are solved. In this model, on top of terms invariant under a continuous symmetry, a highly non-renormalizable term is added to the action that explicitly breaks this symmetry down to a discrete one. In the spontaneously broken phase, the mass of the pseudo-Goldstone is then driven by quantum fluctuations to values that are non-vanishing but that are generically, that is, without fine-tuning, orders of magnitude smaller than the UV scale.

    hep-phhep-th3 citations
15. 15*

    The time-dependent $CP$ asymmetry in $B^0\to K_{\mathrm{res}}\gamma \to {\pi }^{+}{\pi }^{-}{K}_S^0\gamma$ decays

    Simon Akar🇺🇸 · Eli Ben-Haim🇫🇷 · Jeremy Hebinger🇫🇷 · Emi Kou🇫🇷 · Fu-Sheng Yu🇨🇳

    The time-dependent $CP$ asymmetry in $B^0\to K_{\mathrm{res}}\gamma \to {\pi }^{+}{\pi }^{-}{K}_S^0\gamma$ is sensitive to the photon polarisation in the quark level process $b\to s\gamma$. While this polarisation is predominantly left-handed in the standard model, it could be modified by the existence of new physics contributions that may possess different $CP$ properties. In this paper, we derive the $CP$ violation formulae for $B^0\to K_{\mathrm{res}}\gamma \to {\pi }^{+}{\pi }^{-}{K}_S^0\gamma$ including the most dominant intermediate states. We propose a new observable that could be measured in a time-dependent amplitude analysis of $B^0\to {\pi }^{+}{\pi }^{-}{K}_S^0\gamma$ decays, providing a stringent contraint on the photon polarisation. We discuss the future prospects for obtaining such constraints from measurements at Belle II and LHCb.

    hep-phhep-exJHEP(2019)·15 citations
16. 16*

    Scale-invariant scalar field dark matter through the Higgs portal

    Catarina Cosme🇵🇹 · João G. Rosa🇵🇹 · O. Bertolami🇵🇹

    We discuss the dynamics and phenomenology of an oscillating scalar field coupled to the Higgs boson that accounts for the dark matter in the Universe. The model assumes an underlying scale invariance such that the scalar field only acquires mass after the electroweak phase transition, behaving as dark radiation before the latter takes place. While for a positive coupling to the Higgs field the dark scalar is stable, for a negative coupling it acquires a vacuum expectation value after the electroweak phase transition and may decay into photon pairs, albeit with a mean lifetime much larger than the age of the Universe. We explore possible astrophysical and laboratory signatures of such a dark matter candidate in both cases, including annihilation and decay into photons, Higgs decay, photon-dark scalar oscillations and induced oscillations of fundamental constants. We find that dark matter within this scenario will be generically difficult to detect in the near future, except for the promising case of a 7 keV dark scalar decaying into photons, which naturally explains the observed galactic and extra-galactic 3.5 keV X-ray line.

    hep-phastro-ph.COgr-qchep-thJHEP(2018)·47 citations
17. 17*

    Different manifestations of S-matrix poles

    D. F. Ramírez Jiménez🇨🇴 · N. G. Kelkar🇨🇴

    Making use of the analytical properties of the $S$-matrix and a theorem of Mittag-Leffler, model independent non-relativistic expressions for cross sections in single channel elastic scattering, scattering phase shifts and survival probabilities of resonances are derived. Provided certain conditions are satisfied by the poles, the residues can also be estimated analytically. Considerations of the low energy behaviour of the $S$-matrix and cross sections reveal additional conditions on the residues of the poles appearing in the Mittag-Leffler expansions. The exact expressions for the resonant cross section and phase shift are shown to reduce to the commonly used Breit-Wigner formula plus corrections. The latter is shown to approach the exact result with the example of a meson and a baryon resonance. Finally, a comparison of the exact expressions with some realistic examples is presented. The calculations of survival probabilities in particular reveal the reason behind the non-observability of non-exponential decay.

    hep-phnucl-thquant-phAnnals Phys.(2018)·9 citations
18. 18*

    $S$ wave hidden charm - hidden strangeness production in $e^{+}{e}^{-}$ annihilation

    M.B. Voloshin🇺🇸

    It is suggested that the recently observed enhancement of the relative yield in $e^{+}{e}^{-}$ annihilation of states with hidden charm and hidden strangeness above 4.43\,GeV is associated with the $S$ wave production of the charmed strange meson pairs $D_{s0}(2317){\bar{D}}_s^{\ast }+c.c.$ and $D_{s1}^{\ast }(2460){\bar{D}}_s+c.c.$. This mechanism implies a pattern of breaking of the Heavy Quark Spin Symmetry (HQSS) that can be tested in the final channels such as ${\eta }_c(1S)\varphi$, $h_c(1P)\eta$, $h_c(1P){\eta }^{\prime }$ produced in the same energy range.

    hep-phPLB(2018)·2 citations
19. 19*

    Explanation of IceCube spectrum with $\nu \to 3\nu$ neutrino splitting in a $\nu$2HDM model

    Subhendra Mohanty🇮🇳 · Soumya Sadhukhan🇮🇳

    A single power law flux spectrum of high energy neutrinos does not adequately explain the entire 60 TeV to 10 PeV event spectrum observed at IceCube, specially the excess of PeV events and the lack of Glashow resonance events expected at 6.3 PeV cannot be simultaneously explained by a single power law source neutrino flux. Here we consider a model of neutrino splitting $\nu \to 3\nu$ over cosmological distances. Starting from a single power-law spectrum expected from the astrophysical sources, we show that by adjusting the decay length and spectral index one can give a better fit to the observed IceCube events over the entire 1 TeV -6 PeV, compared to that from a single power spectrum. For $\nu \to 3\nu$ neutrino splitting, the flavor ratios of the daughter neutrinos are different from the standard oscillation or invisible decay cases and can be used as a test of this scenario. We propose a $\nu$2HDM where a light Higgs ($\sim 0.1$~eV) mediates neutrino splitting via a one-loop box diagram. The split in the masses of the scalars in the doublet gives a large contribution to the oblique T parameter which is severely constrained. This constraint from the S,T,U oblique parameters can be evaded by the introduction of an extra vector lepton doublet and with mass $\sim 200$ GeV.

    hep-phJHEP(2018)·7 citations
20. 20*

    QCD Shear Viscosity at (almost) NLO

    Jacopo Ghiglieri🇨🇭 · Guy D. Moore🇩🇪 · Derek Teaney🇺🇸

    We compute the shear viscosity of QCD with matter, including almost all next-to-leading order corrections -- that is, corrections suppressed by one power of $g$ relative to leading order. We argue that the still missing terms are small. The next-to-leading order corrections are large and bring $\eta /s$ down by more than a factor of 3 at physically relevant couplings. The perturbative expansion is problematic even at $T\simeq 100$ GeV. The largest next-to-leading order correction to $\eta /s$ arises from modifications to the qhat parameter, which determines the rate of transverse momentum diffusion. We also explore quark number diffusion, and shear viscosity in pure-glue QCD and in QED.

    hep-phnucl-thJHEP(2018)·122 citations
21. 21*

    Inclusive prompt photon production in electron-nucleus scattering at small x

    Kaushik Roy🇺🇸 · Raju Venugopalan🇺🇸

    We compute the differential cross-section for inclusive prompt photon production in deeply inelastic scattering (DIS) of electrons on nuclei at small $x$ in the framework of the Color Glass Condensate (CGC) effective theory. The leading order (LO) computation in this framework resums leading logarithms in $x$ as well as power corrections to all orders in $Q_{s,A}^2/Q^2$, where $Q_{s,A}(x)$ is the nuclear saturation scale. This LO result is proportional to universal dipole and quadrupole Wilson line correlators in the nucleus. In the soft photon limit, the Low-Burnett-Kroll theorem allows us to recover existing results on inclusive DIS dijet production. The $k_{\perp }$ and collinearly factorized expressions for prompt photon production in DIS are also recovered in a leading twist approximation to our result. In the latter case, our result corresponds to the dominant next-to-leading order (NLO) perturbative QCD contribution at small $x$. We next discuss the computation of the NLO corrections to inclusive prompt photon production in the CGC framework. In particular, we emphasize the advantages for higher order computations in inclusive photon production, and for fully inclusive DIS, arising from the simple momentum space structure of the dressed quark and gluon "shock wave" propagators in the "wrong" light cone gauge $A^{-}=0$ for a nucleus moving with $P_N^{+}\to \infty$.

    hep-phnucl-exnucl-thJHEP(2018)·43 citations
22. 22*

    Centrality and transverse momentum dependent suppression of ${\rm Y}(1S)$ and ${\rm Y}(2S)$ in p$-$Pb and Pb$-$Pb collisions at the CERN Large Hadron Collider

    Captain R. Singh🇮🇳 · S. Ganesh🇮🇳 · M. Mishra🇮🇳

    Deconfined QCD matter in heavy-ion collisions has been a topic of paramount interest for many years. Quarkonia suppression in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments indicate the quark-gluon plasma (QGP) formation in such collisions. Recent experiments at LHC has given some indications of hot matter effect in asymmetric p$-$Pb nuclear collisions. Here, we employ a theoretical model to investigate the bottomonium suppression in Pb$-$Pb at $\sqrt{s_{NN}}=2.76$, $5.02$ TeV, and in p$-$Pb at $\sqrt{s_{NN}}=5.02$ TeV center-of-mass energies under a QGP formation scenario. Our present formulation is based on a unified model consisting of suppression due to color screening, gluonic dissociation along with the collisional damping. Regeneration due to correlated $Q\bar{Q}$ pairs has also been taken into account in the current work. We obtain here the net bottomonium suppression in terms of survival probability under the combined effect of suppression plus regeneration in the deconfined QGP medium. We mainly concentrate here on the centrality, $N_{\text{part}}$ and transverse momentum, $(p_t)$ dependence of ${\rm Y}(1S)$ and ${\rm Y}(2S)$ states suppression in Pb$-$Pb and p$-$Pb collisions at mid-rapidity. We compare our model predictions for ${\rm Y}(1S)$ and ${\rm Y}(2S)$ suppression to the corresponding experimental data obtained at the LHC. We find that the experimental observations on $p_t$ and $N_{\text{part}}$ dependent suppression agree reasonably well with our model predictions.

    hep-phEPJC(2019)·21 citations
23. 23*

    Probes for Dark Matter Physics

    Maxim Yu. Khlopov🇷🇺

    The existence of cosmological dark matter is in the bedrock of the modern cosmology. The dark matter is assumed to be nonbaryonic and to consist of new stable particles. However if composite dark matter contains stable electrically charged leptons and quarks bound by ordinary Coulomb interaction in elusive dark atoms, these charged constituents of dark atoms can be the subject of direct experimental test at the colliders. In such models the excessive negatively double charged particles are bound with primordial helium in O-helium atoms, maintaining specific nuclear-interacting form of the dark matter. The successful development of composite dark matter scenarios appeals to experimental search for doubly charged constituents of dark atoms, making experimental search for exotic stable double charged particles experimentum crucis for dark atoms of composite dark matter. (abridged)

    hep-phhep-exInt.J.Mod.Phys.D(2018)·13 citations
24. 24*

    Classical electrodynamics and gauge symmetry of the X-boson

    Mario J. Neves · Lucas Labre · Everton M. C. Abreu

    In this paper we have obtained several new results concerning the X-boson, which is being considered recently as one of the main candidate of the dark matter particle content. The classical electrodynamics for the X-boson model was explored to understand its propagation in space-time. The field equations (Maxwell-type) and the corresponding wave equations were obtained. They indicate the dispersion relations of both a massive and massless particles. These results can be interpreted as a photon and the X-boson (with a mass of 17 MeV), respectively. The gauge symmetry and gauge transformations were discussed. A full model diagonalization was introduced to obtain a Maxwell sector added up to a Proca sector. After that, we have obtained the retarded Green functions which yield the inhomogeneous solutions of the wave equations for the X-boson fields. We have applied this solution to the charge point motion, and we transformed the potential solution to a quadrature problem. In particular, as an example, we have analyzed the point charge in a straight line uniform motion, where the corresponding electromagnetic charge were calculated.

    hep-phhep-thInt.J.Mod.Phys.A(2018)·2 citations
25. 25*

    ${\eta }^{\prime }$ Production in Nucleus-Nucleus collisions as a probe of chiral dynamics

    Giorgio Torrieri🇧🇷

    We argue that, because of the peculiar properties of the ${\eta }^{\prime }$ meson, it is a promising probe of "chiral" dynamics. In particular, we show that a rotating gluon-dominated plasma might lead to an enhanced production of ${\eta }^{\prime }$ w.r.t. statistical model expectations. The presence of a strong topological susceptibility might give a similar effect. In both cases, unlike the statistical model,we expect a non-trivial dependence on event geometry, such as initial volume and impact parameter. Hence, an observation of ${\eta }^{\prime }/{\pi }^0$ ratio depending strongly on impact parameter might be a good indication of chiral effects, either from vorticity or topological phases of QCD

    ↳ nucl-thhep-phnucl-exPRC(2018)·2 citations
26. 26*

    Configurational entropy and $\rho$ and $\varphi$ mesons production in QCD

    G. Karapetyan🇧🇷

    In the present work the electroproduction for diffractive $\rho$ and $\varphi$ mesons by considering AdS/QCD correspondence and Color Glass Condensate (CGC) approximation are studied with respect to the associated dipole cross section, whose parameters are studied and analysed in the framework of the configurational entropy. Our results suggest different quantum states of the nuclear matter, showing that the extremal points of the nuclear configurational entropy is able to reflect a true description of the $\rho$ and $\varphi$ mesons production, using current data concerning light quark masses. During the computations parameters, obtained in fitting procedure, coincide to the experimental within 0.1 %.

    ↳ nucl-thhep-phPLB(2018)·48 citations
27. 27*

    Higgs inflation at the hilltop

    Vera-Maria Enckell🇫🇮 · Kari Enqvist🇫🇮 · Syksy Rasanen🇫🇮 · Eemeli Tomberg🇫🇮

    We study inflation with the non-minimally coupled Standard Model Higgs in the case when quantum corrections generate a hilltop in the potential. We consider both the metric and the Palatini formulation of general relativity. We investigate hilltop inflation in different parts of the Higgs potential and calculate predictions for CMB observables. We run the renormalization group equations up from the electroweak scale and down from the hilltop, adding a jump in-between to account for unknown corrections in the intermediate regime. Within our approximation, no viable hilltop inflation is possible for small field values, where the non-minimal coupling has no role, nor for intermediate field values. For large field values, hilltop inflation works. We find the spectral index to be $n_s\le 0.96$ in both the metric and the Palatini formulation, the upper bound coinciding with the tree-level result. The tensor-to-scalar ratio is $r\le 1.2\times 10^{-3}$ in the metric case and $r\le 2.2\times 10^{-9}$ in the Palatini case. Successful inflation is possible even when the renormalization group running is continuous with no jumps. In the metric formulation, $r$ is smaller than in Higgs inflation on the tree-level plateau or at the critical point, making it possible to distinguish hilltop inflation from these scenarios with next-generation CMB experiments.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·88 citations
28. 28*

    The QCD axion beyond the classical level: A lattice study

    Y. Nakamura🇯🇵 · G. Schierholz🇩🇪

    The axion is a hypothetical elementary particle postulated by the Peccei-Quinn theory to resolve the strong CP problem in QCD. If axions exist and have low mass, they are a candidate for dark matter as well. So far our knowledge of the properties of the QCD axion rests on semi-classical arguments and effective theory. In this work we perform, for the first time, a fully dynamical investigation of the Peccei-Quinn theory, focussing on the axion mass, by simulating the theory on the lattice. The results of the simulation are found to be in conflict with present axion phenomenology.

    ↳ hep-lathep-phhep-thnucl-th3 citations
29. 29*

    Baryon bags in strong coupling QCD

    Christof Gattringer🇦🇹

    We discuss lattice QCD with one flavor of staggered fermions and show that in the path integral the baryon contributions can be fully separated from quark and diquark contributions. The baryonic degrees of freedom are independent of the gauge field and the corresponding free fermion action describes the baryons through the joint propagation of three quarks. The non-baryonic dynamics is described by quark and diquark terms that couple to the gauge field. When evaluating the quark and diquark contributions in the strong coupling limit the partition function completely factorizes into baryon bags and a complementary domain. Baryon bags are regions in space-time where the dynamics is described by a single free fermion made out of three quarks propagating coherently as a baryon. Outside the baryon bags the relevant degrees of freedom are monomers and dimers for quarks and diquarks. The partition sum is a sum over all baryon bag configurations and for each bag a free fermion determinant appears as a weight factor.

    ↳ hep-latcond-mat.otherhep-phPRD(2018)·10 citations
30. 30*

    Host Galaxy Effects in the Susy Model for Supernovae Ia

    L. Clavelli🇺🇸

    For more than forty years virtually all work on the theory of type Ia Supernovae (SN Ia) has assumed that these explosions were due to the transfer of mass to a degenerate star from a partner in a binary system. In these binary models, when the mass of one partner closely approaches the Chandrasekhar maximum for a stable degenerate system, fusion can be initiated and the star explodes. However, there are now a number of indications that fusion could instead be triggered by a phase transition in a sub-Chandrasekhar white dwarf star. Although these indications provide no clue as to what specific phase transition initiates the explosion, it is possible that remarkable and well established host galaxy effects as considered in the present work could point to a specific source of the energy deposition. These host galaxy correlations are, at first glance, surprising since the typical distance scale of white dwarf stars is the earth radius while the typical distance between stars is at the light year scale. Performing a least ${\chi }^2$ fit to the delay time distribution to fix parameters, we give predictions from the susy phase transition model for the host galaxy effects. In addition we discuss a susy insight into the Phillips relation which is basic to the cosmological importance of the type Ia supernovae.

    ↳ astro-ph.HEhep-phInt.J.Mod.Phys.A(2018)·1 citation
31. 31*

    Pion and kaon valence-quark quasiparton distributions

    Shu-Sheng Xu🇨🇳 · Lei Chang🇨🇳 · Craig D. Roberts🇺🇸 · Hong-Shi Zong🇨🇳

    Algebraic Ansaetze for the Poincaré-covariant Bethe-Salpeter wave functions of the pion and kaon are used to calculate their light-front wave functions (LFWFs), parton distribution amplitudes (PDAs), quasi-PDAs (qPDAs), valence parton distribution functions (PDFs), and quasi-PDFs (qPDFs). The LFWFs are broad, concave functions; and the scale of flavour-symmetry violation in the kaon is roughly 15%, being set by the ratio of emergent masses in the $s$-and $u$-quark sectors. qPDAs computed with longitudinal momentum $P_z=1.75$GeV provide a semiquantitatively accurate representation of the objective PDA; but even with $P_z=3$GeV, they cannot provide information about this amplitude's endpoint behaviour. On the valence-quark domain, similar outcomes characterise qPDFs. In this connection, however, the ratio of kaon-to-pion $u$-quark qPDFs is found to provide a good approximation to the true PDF ratio on $0.3\lesssim x\lesssim 0.8$, suggesting that with existing resources computations of ratios of quasi-parton-distributions can yield results that support empirical comparison.

    ↳ nucl-thhep-lathep-phnucl-exPRD(2018)·89 citations
32. 32*

    Nonperturbative Renormalization Group for the Landau-de Gennes Model

    Bin Qin🇨🇳 · Defu Hou🇨🇳 · Mei Huang🇨🇳 · Danning Li🇨🇳 · Hui Zhang🇨🇳

    We studied the nematic isotropic phase transition by applying the functional renormalization group to the Landau-de Gennes model. We derived the flow equations for the effective potential as well as the cubic and quartic "couplings" and the anomalous dimension. We then solved the coupled flow equations on a grid using Newton Raphson method. A first order phase transition is observed. We also investigated the nematic isotropic puzzle (the NI puzzle) in this paper. We obtained the NI transition temperature difference $T_c-T^{\ast }=5.85K$ with sizable improvement over previous results.

    ↳ cond-mat.stat-mechhep-phPRB(2018)·3 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.