Mon·Sep 24, 2018Monday·September 24, 2018

1. 01*

   Weak decays of the axial-vector tetraquark $T_{bb;\bar{u}\bar{d}}^{-}$

   S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · B. Barsbay🇹🇷 · H. Sundu🇹🇷

   The weak decays of the axial-vector tetraquark $T_{bb;\bar{u}\bar{d}}^{-}$ to the scalar state $Z_{bc;\bar{u}\bar{d}}^0$ are investigated using the QCD three-point sum rule approach. In order to explore the process $T_{bb;\bar{u}\bar{d}}^{-}\to Z_{bc;\bar{u}\bar{d}}^{0}l\overline{{\nu }_l}$, we recalculate the spectroscopic parameters of the tetraquark $T_{bb;\bar{u}\bar{d}}^{-}$ and find the mass and coupling of the scalar four-quark system $Z_{bc;\bar{u}\bar{d}}^0$, which are important ingredients of calculations. The spectroscopic parameters of these tetraquarks are computed in the framework of the QCD two-point sum rule method by taking into account various condensates up to dimension ten. The mass of the $T_{bb;\bar{u}\bar{d}}^{-}$ state is found to be $m=(10035\pm 260)\mathrm{MeV}$, which demonstrates that it is stable against the strong and electromagnetic decays. The full width $\Gamma$ and mean lifetime $\tau$ of $T_{bb;\bar{u}\bar{d}}^{-}$ are evaluated using its semileptonic decay channels $T_{bb;\bar{u}\bar{d}}^{-}\to Z_{bc;\bar{u}\bar{d}}^{0}l\overline{{\nu }_l}$, $l=e,\mu$ and $\tau$. The obtained results, $\Gamma =(7.17\pm 1.23)\times 10^{-8}\mathrm{MeV}$ and $\tau =9.18_{-1.34}^{+1.90}\mathrm{fs}$, can be useful for experimental investigations of the doubly-heavy tetraquarks.

   hep-phhep-exhep-latPRD(2019)·54 citations
2. 02*

   Lepto-philic 2-HDM + singlet scalar portal induced fermionic dark matter

   Sukanta Dutta🇮🇳 · Ashok Goyal🇮🇳 · Manvinder Pal Singh🇮🇳

   We explore the possibility that the discrepancy in the observed anomalous magnetic moment of the muon $\Delta a_{\mu }$ and the predicted relic abundance of Dark Matter by Planck data, can be explained in a lepto-philic 2-HDM augmented by a real SM singlet scalar of mass $\sim$ 10-80 GeV. We constrain the model from the observed Higgs Decay width at LHC, LEP searches for low mass exotic scalars and anomalous magnetic moment of an electron $\Delta a_e$. This constrained light singlet scalar serves as a portal for the fermionic Dark Matter, which contributes to the required relic density of the universe. A large region of model parameter space is found to be consistent with the present observations from the Direct and Indirect DM detection experiments.

   hep-phJHEP(2019)·5 citations
3. 03*

   Sensitivity of future lepton colliders to the search for charged lepton flavor violation

   Tong Li🇨🇳 · Michael A. Schmidt🇦🇺

   The observation of lepton flavor violation indicates new physics beyond the Standard Model. Lepton colliders are ideal facilities to probe charged lepton flavor violation (CLFV) signals induced by new physics at high energy. In this work we perform a comprehensive study of the sensitivity of future lepton colliders to charged lepton flavor violation. We consider the most general renormalizable Lagrangian coupling two leptons to new bosonic particles, involving both $\Delta L=0$ and $\Delta L=2$ interactions. The CLFV processes are introduced by the exchange of off-shell new particles at tree-level. We find that CEPC, ILC, FCC-ee, and CLIC each provide a complementary probe of CLFV couplings to low-energy precision experiments for $\tau$ lepton(s) in final states, while low-energy precision experiments are more sensitive in the absence of $\tau$ leptons.

   hep-phPRD(2019)·28 citations
4. 04*

   Breakdown of NRQCD Factorization in Processes Involving Two Quarkonia and its Cure

   Zhi-Guo He🇩🇪 · Bernd A. Kniehl🇩🇪 · Xiang-Peng Wang🇩🇪

   We study inclusive processes involving two heavy quarkonia in nonrelativisitic QCD (NRQCD) and demonstrate that, in the presence of two P-wave Fock states, NRQCD factorization breaks down, leaving uncanceled infrared singularities. As phenomenologically important examples, we consider the decay ${\rm Y}\to {\chi }_{cJ}+X$ via $b\bar{b}({}^3{P}_{J_b}^{[8]})\to c\bar{c}({}^3{P}_J^{[1]})+gg$ and the production process $e^{+}{e}^{-}\to J/\psi +{\chi }_{cJ}+X$ via $e^{+}{e}^{-}\to c\bar{c}({}^3{P}_{J_1}^{[8]})+c\bar{c}({}^3{P}_J^{[1]})+g$. We infer that such singularities will appear for double quarkonium hadroproduction at next-to-leading order. As a solution to this problem, we introduce to NRQCD effective field theory new types of operators whose quantum corrections absorb these singularities.

   hep-phPRL(2018)·14 citations
5. 05*

   Pentaquark states with the $QQQq\bar{q}$ configuration in a simple model

   Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Yu-Nan Liu🇨🇳 · Zong-Guo Si🇨🇳 · Jing Wu🇨🇳

   We discuss the mass splittings for the $S$-wave triply heavy pentaquark states with the $QQQq\bar{q}$ $(Q=b,c;q=u,d,s)$ configuration which is a mirror structure of $Q\bar{Q}qqq$. The latter configuration is related with the nature of $P_c(4380)$ observed by the LHCb Collaboration. The considered pentaquark masses are roughly estimated with a simple method. One finds that such states are probably not narrow even if they do exist. This leaves room for molecule interpretation for a state around the low-lying threshold of a doubly heavy baryon and a heavy-light meson, e.g. ${\Xi }_{cc}D$, if it were observed. As a by product, we conjecture that upper limits for the masses of the conventional triply heavy baryons can be determined by the masses of the conventional doubly heavy baryons.

   hep-phhep-exhep-latnucl-thEPJC(2019)·29 citations
6. 06*

   Photon dispersion relations in $A_0$-background

   M.Bordag🇩🇪 · V.Skalozub🇺🇦

   We calculate the photon dispersion relations generated by the quark loop in a quark-gluon plasma with the color $A_0$ background condensate $A_0^c=A_0^{c3}+A_0^{c8}$ = const. It is found that both transversal and longitudinal modes are exited. They have a gap at low momenta and are stable in high temperature approximation. The background fields act as imaginary chemical potentials and decrease the photon frequencies compared to the case of zero background. The comparison with QED plasma with chemical potential is discussed.

   hep-phhep-thEur.Phys.J.Plus(2019)·6 citations
7. 07*

   Probing the $X(4350)$ in $\gamma \gamma$ interactions at the LHC

   V. P. Goncalves🇧🇷 · B. D. Moreira🇧🇷

   The production of $X(4350)$ in the $\gamma \gamma$ interactions that occur in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) is investigated and predictions for the kinematical ranges probed by the ALICE and LHCb Collaborations are presented. We focus on the $\gamma \gamma \to \varphi J/\Psi$ process, which have been measured by the Belle Collaboration, and present parameter free predictions for the total cross sections at the LHC energies. Our results demonstrate that the experimental study of this process is feasible and can be used to confirm or not the existence of the $X(4350)$ state. Finally, for completeness, we present predictions for the production of the $X(3915)$ state in the $\gamma \gamma \to \omega J/\Psi$ process and show that this exotic state can also be probed in $\gamma \gamma$ interactions at the LHC.

   hep-phhep-exEPJC(2019)·25 citations
8. 08*

   Twin Peaks: A possible signal in the production of resonances beyond special relativity

   G. Albalate🇪🇸 · J.M. Carmona🇪🇸 · J.L. Cortes🇪🇸 · J.J. Relancio🇪🇸

   It is usually expected that quantum gravity corrections will modify somehow the symmetries of special relativity. In this paper we point out that the possibility of very low-energy (with respect to the Planck energy) modifications to special relativity in the framework of a deformed relativistic theory is not ruled out, and that, depending on the value of that scale, such a possibility could be tested in accelerator physics. In particular, we take a simple example of a relativistic kinematics beyond special relativity from the literature, and obtain a remarkable effect: two correlated peaks ("twin peaks") associated to a single resonance. We analyze this phenomenology in detail, use LEP data to put constraints of the order of TeV on the scale of corrections to special relativity, and note that such an effect might be observable in a future very high-energy proton collider.

   hep-phgr-qchep-exSymmetry(2018)·11 citations
9. 09*

   Chiral Cherenkov and chiral transition radiation in anisotropic matter

   Kirill Tuchin🇺🇸

   A significant contribution to the electromagnetic radiation by a fast electric charge moving in anisotropic chiral matter arises from spontaneous photon radiation due to the chiral anomaly. While such a process, also known as the "vacuum Cherenkov radiation", is forbidden in the QED vacuum, it can occur in chiral matter, where it is more appropriate to call it the "chiral Cherenkov radiation". Its contribution to the radiation spectrum is of order ${\alpha }^2$ compared to ${\alpha }^3$ of the bremsstrahlung. I derive the frequency spectrum and the angular distribution of this radiation in the high energy limit. The quantum effects due to the hard photon emission and the fermion mass are taken into account. The obtained spectra are analyzed in the case the quark-gluon plasma and a Weyl semimetal.

   hep-phcond-mat.mes-hallnucl-thPRD(2018)·18 citations
10. 10*

    Model-Independent Bounds on $R(J/\psi )$ via Dispersive Relations

    Henry Lamm🇺🇸

    Model-independent bounds on $R(J/\psi )\equiv \mathcal{B}\mathcal{R}(B_c^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })/$ $\mathcal{B}\mathcal{R}(B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })$ are obtained through a combination of dispersive relations, heavy-quark relations at zero-recoil, and the limited existing form factor determinations from lattice QCD. The resulting 95% confidence-level bound, $0.20\le R(J/\psi )\le 0.39$, agrees with the recent LHCb result at $1.3\sigma$, and removes the dominant model-dependent uncertainty from theory predictions. Using the same techniques, a prediction of $R({\eta }_c)=0.29(5)$ is obtained.

    hep-phhep-exhep-lat1 citation
11. 11*

    On the Maximal Strength of a First-Order Electroweak Phase Transition and its Gravitational Wave Signal

    John Ellis🇬🇧 · Marek Lewicki🇬🇧 · José Miguel No🇬🇧

    What is the maximum possible strength of a first-order electroweak phase transition and the resulting gravitational wave (GW) signal? While naively one might expect that supercooling could increase the strength of the transition to very high values, for strong supercooling the Universe is no longer radiation-dominated and the vacuum energy of the unstable minimum of the potential dominates the expansion, which can jeopardize the successful completion of the phase transition. After providing a general treatment for the nucleation, growth and percolation of broken phase bubbles during a first-order phase transition that encompasses the case of significant supercooling, we study the conditions for successful bubble percolation and completion of the electroweak phase transition in theories beyond the Standard Model featuring polynominal potentials. For such theories, these conditions set a lower bound on the temperature of the transition. Since the plasma cannot be significantly diluted, the resulting GW signal originates mostly from sound waves and turbulence in the plasma, rather than bubble collisions. We find the peak frequency of the GW signal from the phase transition to be generically $f\gtrsim 10^{-4}$ Hz. We also study the condition for GW production by sound waves to be long-lasting (GW source active for approximately a Hubble time), showing it is generally not fulfilled in concrete scenarios. Because of this the sound wave GW signal could be weakened, with turbulence setting in earlier, resulting in a smaller overall GW signal as compared to current literature predictions.

    hep-phastro-ph.COJCAP(2019)·472 citations
12. 12*

    Leptogenesis from Low Energy $CP$ Violation

    K. Moffat🇬🇧 · S. Pascoli🇬🇧 · S.T. Petcov🇮🇹 · J. Turner🇺🇸

    We revisit the possibility of producing the observed baryon asymmetry of the Universe via thermal leptogenesis, where $CP$ violation comes exclusively from the low-energy phases of the neutrino mixing matrix. We demonstrate the viability of thermal flavoured leptogenesis across seven orders of magnitude $\left(10^6<T\text{ (GeV)}<10^{13}\right)$, using modern numerical machinery, where the lower bound can be reached only if flavour effects are taken into account and its value depends on the allowed degree of cancellation between the tree-level and radiative contributions to the light neutrino masses. At very high scales $\left(T\gg 10^{12}\text{ GeV}\right)$, we clarify that thermal leptogenesis is sensitive to the low-energy phases, in contradiction with what is usually claimed in the literature. In particular we demonstrate that Majorana-phase leptogenesis is in general viable while Dirac-phase leptogenesis requires some level of fine-tuning.

    hep-phJHEP(2019)·62 citations
13. 13*

    Improved constraints on the mixing and mass of $Z^{\prime }$ bosons from resonant diboson searches at the LHC at $\sqrt{s}=13$ TeV and predictions for Run II

    I. D. Bobovnikov🇩🇪 · P. Osland🇳🇴 · A. A. Pankov🇧🇾

    New neutral vector bosons $Z^{\prime }$ decaying to charged gauge boson pairs $W^{+}{W}^{-}$ are predicted in many scenarios of new physics, including models with an extended gauge sector such as $E_6$, left-right symmetric $Z_{\mathrm{LRS}}^{\prime }$ and the sequential standard model $Z_{\mathrm{SSM}}^{\prime }$. For these benchmark models we calculate and present theoretical expectations for different values of the $Z^{\prime }$ mass $M_2$ and mixing parameter $\xi$. Our results are based on the narrow width approximation which allows to make a convenient comparison of experiment to theoretical benchmark models. The diboson production allows to place stringent constraints on the $Z$-$Z^{\prime }$ mixing angle and the $Z^{\prime }$ mass, which we determine by using data from $pp$ collisions at $\sqrt{s}=13$ TeV recorded by the ATLAS detector at the CERN LHC, with integrated luminosity of $\sim$ 36 fb${}^{-1}$. By comparing the experimental limits to the theoretical predictions for the total cross section of $Z^{\prime }$ resonant production and its subsequent decay into $W^{+}{W}^{-}$ pairs, we show that the derived constraints on the mixing angle for the benchmark models are of the order of a few $\times 10^{-4}$, i.e., greatly improved with respect to those derived from the global analysis of electroweak data. We combine the limits derived from diboson production data with those obtained from the Drell--Yan process in order to significantly extend the exclusion region in the $M_2$-$\xi$ parameter plane. Also, we demonstrate that further improvement on the constraining of this mixing can be achieved through analysis of the full set of Run~II data.

    hep-phPRD(2018)·24 citations
14. 14*

    Towards the determination of heavy-quark transport coefficients in quark-gluon plasma

    Shanshan Cao🇺🇸 · Gabriele Coci🇮🇹 · Santosh Kumar Das🇮🇳 · Weiyao Ke🇺🇸 · Shuai Y.F. Liu🇺🇸 · Salvatore Plumari🇮🇹 · Taesoo Song🇩🇪 · Yingru Xu🇺🇸 · Jörg Aichelin🇫🇷 · Steffen Bass🇺🇸 · Elena Bratkovskaya🇩🇪 · Xing Dong🇺🇸 and 7 other authors

    Several transport models have been employed in recent years to analyze heavy-flavor meson spectra in high-energy heavy-ion collisions. Heavy-quark transport coefficients extracted from these models with their default parameters vary, however, by up to a factor of 5 at high momenta. To investigate the origin of this large theoretical uncertainty, a systematic comparison of heavy-quark transport coefficients is carried out between various transport models. Within a common scheme devised for the nuclear modification factor of charm quarks in a brick medium of a quark-gluon plasma, the systematic uncertainty of the extracted drag coefficient among these models is shown to be reduced to a factor of 2, which can be viewed as the smallest intrinsic systematical error band achievable at present time. This indicates the importance of a realistic hydrodynamic evolution constrained by bulk hadron spectra and of heavy-quark hadronization for understanding the final heavy-flavor hadron spectra and extracting heavy-quark drag coefficient. The transverse transport coefficient is less constrained due to the influence of the underlying mechanism for heavy-quark medium interaction. Additional constraints on transport models such as energy loss fluctuation and transverse-momentum broadening can further reduce theoretical uncertainties in the extracted transport coefficients.

    ↳ nucl-thhep-phnucl-exPRC(2019)·200 citations
15. 15*

    Diffusion of charm and beauty in the Glasma

    Marco Ruggieri🇨🇳 · Santosh Kumar Das🇮🇳

    Relativistic nuclear collisions offer a unique way to study strong interactions at very high energy. The collision process can be described within the gluon saturation framework as the interaction of two colored glasses, and because of this interaction strong longitudinal gluon fields, namely the Glasma, are produced immediately after the collision. Besides, heavy quarks are also produced in the very early stage and because of their large mass and small concentration, their motion does not affect the evolution of the Glasma, thus behaving as ideal probes of the Glasma itself. We study the evolution of the heavy quarks in the Glasma allegedly produced in high energy p-Pb collisions by solving consistently the equations of motion of the quarks in the evolving Glasma fields. We find that this motion can be understood in terms of diffusion in momentum space, similarly to the random motion of a heavy probe in a hot thermalized medium. We show how the diffusion of heavy probes affects the nuclear modification factor of D and B mesons in p-Pb collisions.

    ↳ nucl-thhep-phEPJ Web Conf.(2018)·10 citations
16. 16*

    Affleck-Dine baryogenesis via mass splitting

    Eugeny Babichev🇫🇷 · Dmitry Gorbunov🇷🇺 · Sabir Ramazanov🇨🇿

    We introduce a class of non-supersymmetric models explaining baryogenesis a la Affleck-Dine, which use a decay of two superheavy scalar fields with close masses. These scalars acquire non-zero expectation values during inflation through linear couplings to a function of an inflaton. After the inflaton decay, the model possesses approximate U(1)-invariance, explicitly broken by a small mass splitting. This splitting leads to the baryogenesis in the early Universe. Resulting baryon asymmetry is automatically small for the scalars with the masses about the Grand Unification scale and larger. It is fully determined by the inflaton dynamics and the Lagrangian parameters, i.e., is independent of initial pre-inflationary conditions for the scalars. As a consequence, baryon perturbations are purely adiabatic. We point out a possible origin of the mass splitting: masses of scalars degenerate at some large energy scale may acquire different loop corrections due to the interaction with the inflaton. Compared to electroweak baryogenesis and conventional Affleck-Dine scenarios, our mechanism generically leads to the proton decay suppressed by the powers of the superheavy scalar masses, which makes this scenario potentially testable.

    ↳ astro-ph.COhep-phhep-thPLB(2019)·21 citations
17. 17*

    Faddeev-Popov Matrix in Linear Covariant Gauge: First Results

    Attilio Cucchieri🇧🇷 · David Dudal🇧🇪 · Tereza Mendes🇧🇷 · Orlando Oliveira🇵🇹 · Martin Roelfs🇧🇪 · Paulo J. Silva🇵🇹

    We discuss a possible definition of the Faddeev-Popov matrix for the minimal linear covariant gauge on the lattice and present first results for the ghost propagator. We consider Yang-Mills theory in four space-time dimensions, for SU(2) and SU(3) gauge groups.

    ↳ hep-lathep-phhep-thPRD(2018)·17 citations
18. 18*

    Asymmetric Dark Stars and Neutron Star Stability

    Moira I. Gresham🇺🇸 · Kathryn M. Zurek🇺🇸

    We consider gravitationally bound states of asymmetric dark matter (ADM stars), and the impact of ADM capture on the stability of neutron stars. We derive and interpret the equation of state for ADM with both attractive and repulsive interactions, and solve the Tolman-Oppenheimer-Volkoff equations to find equilibrium sequences and maximum masses of ADM stars. Gravitational wave searches can utilize our solutions to model exotic compact objects (ECOs). Our results for attractive interactions differ substantially from those in the literature, where fermionic ADM with attractive self-interactions was employed to destabilize neutron stars more effectively than non-interacting fermionic ADM. By contrast, we argue that fermionic ADM with an attractive force is no more effective in destabilizing neutron stars than fermionic ADM with no self-interactions.

    ↳ astro-ph.COgr-qchep-phPRD(2019)·143 citations
19. 19*

    The quenched SU(2) adjoint scalar propagator in minimal Landau gauge

    Axel Maas🇦🇹

    It is a long-standing question whether the confinement of matter fields in QCD has an imprint in the (gauge-dependent) correlation functions, especially the propagators. In particular in the quenched case a fundamental difference could be expected between adjoint and fundamental matter. In a preceding investigation the propagator of a fundamental scalar has been studied, showing no obvious sign of confinement. Here, complementary, the adjoint scalar propagator is investigated over a wide range of parameters in the minimal Landau gauge using lattice gauge theory. This study is performed in two, three, and four dimensions in quenched SU(2) Yang-Mills theory, both in momentum space and position space. No conclusive difference between both cases is found.

    ↳ hep-lathep-phPRD(2019)·4 citations
20. 20*

    Strange Nuclear Physics from QCD on Lattice

    Takashi Inoue (for HAL QCD Collaboration)🇯🇵

    We study single-particle potential of Lambda, Sigma, and Xi hyperons in nucleonic matter starting from the fundamental theory of the strong interaction, QCD. First we carry out a lattice QCD numerical simulation, and extract baryon-baryon interactions from QCD by means of the HAL QCD method. We employ a full QCD gauge configuration ensemble at almost physical point so that we can study the physical world, hence mass of hadrons are nearly physical, for example, pion mass is 146 MeV, kaon mass is 525 MeV, and nucleon mass is 958 MeV. Then, we apply the obtained hyperon interactions to the Brueckner-Hartree-Fock many-nucleon theory, and calculate single-particle potential of hyperons in nucleonic matter U_{Y}(k). We obtain for hyperons stopping in the symmetric nuclear matter at the normal nuclear matter density, U_{Lambda}(0)=-28 MeV, U_{Sigma}(0)=+15 MeV, and U_{Xi}(0)=-4 MeV with a statistical error about +/- 2 MeV associated with our Monte Carlo simulation. These results are qualitatively compatible with values suggested from hypernuclear experiments. This success is remarkable and very encouraging since this proves that our approach to strange nuclear physics starting from QCD is essentially correct.

    ↳ hep-lathep-phnucl-exnucl-thAIP Conf.Proc.(2019)·47 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.