Tue·May 2, 2017Tuesday·May 2, 2017

1. 01*

   Baryogenesis from L-violating Higgs-doublet decay in the density-matrix formalism

   Thomas Hambye🇧🇪 · Daniele Teresi🇧🇪

   We compute in the density-matrix formalism the baryon asymmetry generated by the decay of the Higgs doublet into a right-handed (RH) neutrino and a Standard Model lepton. The emphasis is put on the baryon asymmetry produced by the total lepton-number violating decay. From the derivation of the corresponding evolution equations, and from their integration, we find that this contribution is fully relevant for large parts of the parameter space. This confirms the results found recently in the CP-violating decay formalism with thermal corrections and shows in particular that the lepton-number violating processes are important not only for high-scale leptogenesis but also when the RH-neutrino masses are in the GeV range. For large values of the Yukawa couplings, we also find that the strong washout is generically much milder for this total lepton-number violating part than for the usual RH-neutrino oscillation flavour part.

   hep-phastro-ph.COPRD(2017)·73 citations
2. 02*

   Dark matter repulsion could thwart direct detection

   Hooman Davoudiasl🇺🇸

   We consider a feeble repulsive interaction between ordinary matter and dark matter, with a range similar to or larger than the size of the Earth. Dark matter can thus be repelled from the Earth, leading to null results in direct detection experiments, regardless of the strength of the short-distance interactions of dark matter with atoms. Generically, such a repulsive force would not allow trapping of dark matter inside astronomical bodies. In this scenario, accelerator-based experiments may furnish the only robust signals of asymmetric dark matter models, which typically lack indirect signals from self-annihilation. Some of the variants of our hypothesis are also briefly discussed.

   hep-phastro-ph.COPRD(2017)·11 citations
3. 03*

   Fierz-complete NJL model study: fixed points and phase structure at finite temperature and density

   Jens Braun🇩🇪 · Marc Leonhardt🇩🇪 · Martin Pospiech🇩🇪

   Nambu-Jona-Lasinio-type models are frequently employed as low-energy models in various research fields. With respect to the theory of the strong interaction, this class of models is indeed often used to analyze the structure of the phase diagram at finite temperature and quark chemical potential. The predictions from such models for the phase structure at finite quark chemical potential are of particular interest as this regime is difficult to access with lattice Monte Carlo approaches. In this work, we consider a Fierz-complete version of a Nambu-Jona-Lasinio model. By studying its renormalization group flow, we analyze in detail how Fierz-incomplete approximations affect the predictive power of such model studies. In particular, we investigate the curvature of the phase boundary at small chemical potential, the critical value of the chemical potential above which no spontaneous symmetry breaking occurs, and the possible interpretation of the underlying dynamics in terms of difermion-type degrees of freedom. We find that the inclusion of four-fermion channels other than the conventional scalar-pseudoscalar channel is not only important at large chemical potential but also leaves a significant imprint on the dynamics at small chemical potential as measured by the curvature of the finite-temperature phase boundary.

   hep-phnucl-thPRD(2017)·71 citations
4. 04*

   Hadronic molecules

   Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Ulf-G. Meißner🇩🇪 · Qian Wang🇩🇪 · Qiang Zhao🇨🇳 · Bing-Song Zou🇨🇳

   A large number of experimental discoveries especially in the heavy quarkonium sector that did not at all fit to the expectations of the until then very successful quark model led to a renaissance of hadron spectroscopy. Among various explanations of the internal structure of these excitations, hadronic molecules, being analogues of light nuclei, play a unique role since for those predictions can be made with controlled uncertainty. We review experimental evidences of various candidates of hadronic molecules, and methods of identifying such structures. Nonrelativistic effective field theories are the suitable framework for studying hadronic molecules, and are discussed in both the continuum and finite volumes. Also pertinent lattice QCD results are presented. Further, we discuss the production mechanisms and decays of hadronic molecules, and comment on the reliability of certain assertions often made in the literature.

   hep-phhep-exhep-latnucl-thRMP(2018)·1695 citations
5. 05*

   Formation of hadrons at chemical freeze-out

   David Blaschke🇵🇱 · Jakub Jankowski🇵🇱 · Michal Naskret🇵🇱

   We use a kinetic condition to predict the chemical freeze-out parameters for hadronic species produced in heavy ion collisions. The resulting freeze-out lines for different hadrons lie close to one another in the temperature and baryochemical potential plane, defining a universal, narrow region. The chemical freeze-out is driven by the localization of hadrons due to the chiral symmetry breaking and confining aspects of the QCD transition.

   hep-phnucl-th8 citations
6. 06*

   Fragmentation of $\omega$ and $\varphi$ Mesons in $e^{+}{e}^{-}$ and $pp$ Collisions at NLO

   H. Saveetha🇮🇳 · D. Indumathi🇮🇳

   A combined analysis of both $e^{+}{e}^{-}$ (LEP, SLD) and $pp$ (RHIC-PHENIX and LHC-ALICE) hadroproduction processes are done for the first time for the vector meson nonet at the next-to-leading order (NLO) using a model with broken SU(3) symmetry. The transverse momentum ($p_T$) and rapidity ($y$) dependence of the differential cross section for $\omega$ and $\varphi$ mesons of the $pp$ data are also discussed. The input universal quark (valence and singlet) fragmentation functions at a starting scale of $Q_0^2=1.5$ GeV${}^2$, after evolution, have values that are consistent with the earlier analysis for $e^{+}{e}^{-}$ at NLO. However, the universal gluon fragmentation function is now well determined from this study with significantly smaller error bars, as the $pp$ hadroproduction cross section is particularly sensitive to the gluon fragmentation since it occurs at the same order as quark fragmentation, in contrast to the $e^{+}{e}^{-}$ hadroproduction process. Additional parameters involved in describing strangeness and sea suppression and octet-singlet mixing are found to be close to earlier analysis; in addition, a new relation between gluon and sea suppression in $K^{\ast }$ and $\varphi$ hadroproduction has been observed.

   hep-phInt.J.Mod.Phys.A(2017)·4 citations
7. 07*

   IDM and not only

   Agnieszka Ilnicka🇨🇭 · Maria Krawczyk🇵🇱 · Tania Robens🇺🇸 · Dorota Sokolowska🇵🇱

   In this note, we discuss recent updates to a previous scan for the Inert Doublet Model, a two Higgs doublet model with a dark matter candidate. We explicitly show the inclusion of updated constraints on direct detection reduces the allowed parameter space significantly. We furthermore discuss the IDMS - an extension of the IDM with a complex singlet.

   hep-phPoS(2017)·2 citations
8. 08*

   Spin-dependent constraints on blind spots for thermal singlino-higgsino dark matter with(out) light singlets

   Marcin Badziak🇵🇱 · Marek Olechowski🇵🇱 · Paweł Szczerbiak🇵🇱

   The LUX experiment has recently set very strong constraints on spin-independent interactions of WIMP with nuclei. These null results can be accommodated in NMSSM provided that the effective spin-independent coupling of the LSP to nucleons is suppressed. We investigate thermal relic abundance of singlino-higgsino LSP in these so-called spin-independent blind spots and derive current constraints and prospects for direct detection of spin-dependent interactions of the LSP with nuclei providing strong constraints on parameter space. We show that if the Higgs boson is the only light scalar the new LUX constraints set a lower bound on the LSP mass of about 300 GeV except for a small range around the half of $Z^0$ boson masses where resonant annihilation via $Z^0$ exchange dominates. XENON1T will probe entire range of LSP masses except for a tiny $Z^0$-resonant region that may be tested by the LZ experiment. These conclusions apply to general singlet-doublet dark matter annihilating dominantly to $t\bar{t}$. Presence of light singlet (pseudo)scalars generically relaxes the constraints because new LSP (resonant and non-resonant) annihilation channels become important. Even away from resonant regions, the lower limit on the LSP mass from LUX is relaxed to about 250 GeV while XENON1T may not be sensitive to the LSP masses above about 400 GeV.

   hep-phJHEP(2017)·38 citations
9. 09*

   Quasi-Parton Distribution Function in Lattice Perturbation Theory

   Xiaonu Xiong🇩🇪 · Thomas Luu🇩🇪 · Ulf-G. Meißner🇩🇪

   Large momentum effective field theory provides a new direction for lattice QCD calculations of hadronic structure functions, such as parton distribution functions (PDFs), meson distribution amplitudes, and so on, directly with $x$-dependence. In the framework of Lattice Perturbation Theory (LPT), we compute the one-loop quark-in-quark quasi-PDF with the naïve fermion action (${\tilde{q}}^{\mathrm{nv}}$) and quasi-PDF with Wilson-Clover action (${\tilde{q}}^{\mathrm{WC}}$) and show that ${\tilde{q}}^{\mathrm{nv}}$ reduces to the continuum quasi-PDF in the continuum limit. We point out, however, that the continuum limit and massless quark limit do not commute. We find that the condition to recover the same collinear divergence that the quasi-PDF has in continuum QCD is $a{P}_3^2\approx m$ and $m\ll P_3$, while the condition to fully recover the continuum quasi-PDF is $a{P}_3^2\ll m\ll P_3$, where $P_3$ is the momentum in the direction of the quark's motion (longitudinal direction). These two conditions are based on perturbation calculations and should not be applied to non-perturbative calculations because the non-perturbative effects cure the collinear divergence. The correction to the quasi-PDF using the naïve fermion action is due to the Wilson term and can be viewed as an $\mathcal{O}\left(a^1\right)$ correction. For nonzero $r$, the $\mathcal{O}\left(a^1\right)$ corrections are subsequently mixed with the quasi-PDF using the naïve fermion action.

   hep-phhep-lat54 citations
10. 10*

    Muon g-2 Theory: the Hadronic Part

    Fred Jegerlehner🇩🇪

    I present a status report of the hadronic vacuum polarization effects for the muon $g-2$, to be considered as an update of [1]. The update concerns recent new inclusive $R$ measurements from KEDR in the energy range 1.84 to 3.72 GeV. For the leading order contributions I find $a_{\mu }^{\mathrm{had}(1)}=(688.07\pm 4.14)[688.77\pm 3.38]\times 10^{-10}$ based on $e^{+}{e}^{-}$data [incl. $\tau$ data], $a_{\mu }^{\mathrm{had}(2)}=(-9.93\pm 0.07)\times 10^{-10}$ (NLO) and $a_{\mu }^{\mathrm{had}(3)}=(1.22\pm 0.01)\times 10^{-10}$ (NNLO). Collecting recent progress in the hadronic light-by-light scattering I adopt ${\pi }^0,\eta ,{\eta }^{\prime }$ [$95\pm 12$] + axial--vector [$8\pm 3$] + scalar [$-6\pm 1$] + $\pi ,K$ loops [$-20\pm 5$] + quark loops [$22\pm 4$] + tensor [$1\pm 0$] + NLO [$3\pm 2$] which yields $a_{\mu }^{(6)}(\mathrm{lbl},\mathrm{had})=(103\pm 29)\times 10^{-11}.$ With these updates I find $a_{\mu }^{\exp }-a_{\mu }^{\mathrm{the}}=(31.3\pm 7.7)\times 10^{-10}$ a 4.1 $\sigma$ deviation. Recent lattice QCD results and future prospects to improve hadronic contributions are discussed.

    hep-phEPJ Web Conf.(2018)·173 citations
11. 11*

    Particle states of Lattice QCD

    A. S. Kapoyannis🇬🇷 · A. D. Panagiotou🇬🇷

    We determine the degeneracy factor and the average particle mass of particles that produce the Lattice QCD pressure and specific entropy at zero baryon chemical potential. The number of states of the gluons and the quarks are found to converge above $T=$230 MeV to almost constant values, close to the number of states of an ideal Quark-Gluon Phase, while their assigned masses retain high values. The number of states and the average mass of a system containing quarks in interaction with gluons are found to decrease steeply with increase of temperature between $T\sim 150$ and 160 MeV, a region contained within the region of the chiral transition. The minimum value of the number of states within this temperature interval indicates that the states are of hadronic nature.

    hep-phhep-latEPJC(2017)·1 citation
12. 12*

    Neutrino Mixing and Leptonic CP Violation from $S_4$ Flavour and Generalised CP Symmetries

    J. T. Penedo🇮🇹 · S. T. Petcov🇮🇹 · A. V. Titov🇮🇹

    We consider a class of models of neutrino mixing with $S_4$ lepton flavour symmetry combined with a generalised CP symmetry, which are broken to residual $Z_2$ and $Z_2\times H_{\mathrm{CP}}^{\nu }$ symmetries in the charged lepton and neutrino sectors, respectively, $H_{\mathrm{CP}}^{\nu }$ being a remnant CP symmetry of the neutrino Majorana mass term. In this set-up the neutrino mixing angles and CP violation (CPV) phases of the neutrino mixing matrix depend on three real parameters - two angles and a phase. We classify all phenomenologically viable mixing patterns and derive predictions for the Dirac and Majorana CPV phases. Further, we use the results obtained on the neutrino mixing angles and leptonic CPV phases to derive predictions for the effective Majorana mass in neutrinoless double beta decay.

    hep-phJHEP(2017)·50 citations
13. 13*

    The impact of the LHC Z-boson transverse momentum data on PDF determinations

    Radja Boughezal🇺🇸 · Alberto Guffanti🇮🇹 · Frank Petriello🇺🇸 · Maria Ubiali🇬🇧

    The LHC has recently released precise measurements of the transverse momentum distribution of the Z-boson that provide a unique constraint on the structure of the proton. Theoretical developments now allow the prediction of these observables through next-to-next-to-leading order (NNLO) in perturbative QCD. In this work we study the impact of incorporating these latest advances into a determination of parton distribution functions (PDFs) through NNLO including the recent ATLAS and CMS 7 TeV and 8 TeV $p_T^Z$ data. We investigate the consistency of these measurements in a global fit to the available data and quantify the impact of including the $p_T^Z$ distributions on the PDFs. The inclusion of these new data sets significantly reduces the uncertainties on select parton distributions and the corresponding parton-parton luminosities. In particular, we find that the $p_T^Z$ data ultimately leads to a reduction of the PDF uncertainty on the gluon-fusion and vector-boson fusion Higgs production cross sections by about 30%, while keeping the central values nearly unchanged.

    hep-phJHEP(2017)·67 citations
14. 14*

    Radiative decay of heavy neutrinos at MiniBooNE and MicroBooNE

    Luis Alvarez-Ruso🇪🇸 · Eduardo Saul-Sala🇪🇸

    The MiniBooNE experiment reported results from the analysis of ${\nu }_e$ and ${\overline{\nu }}_e$ appearance searches, which showed an excess of signal-like events at low reconstructed neutrino energies with respect to the expected background. A proposed explanation for this anomaly is based on the existence of a heavy ($\sim 50$~MeV) sterile neutrino. These ${\nu }_h$ would be produced by ${\nu }_{\mu }$ electromagnetic and neutral current interactions. A fraction of them decays radiatively inside the detector. The emitted photon is misidentified as an electron or positron in MiniBooNE. We have investigated the ${\nu }_h$ production by coherent and incoherent electroweak interactions at the MiniBooNE and MicroBooNE targets, CH${}_2$ and Ar, respectively. Studying the ${\nu }_h$ propagation inside the detector, we obtain the energy and angular distributions of emitted photons for a choice of model parameters. The distinctive shape and total number of photon events from this mechanism at MicroBooNE makes its experimental investigation possible.

    hep-phhep-exnucl-th14 citations
15. 15*

    Constraint on the light quark mass $m_q$ from QCD Sum Rules in the $I=0$ scalar channel

    Jia-Min Yuan🇨🇳 · Zhu-Feng Zhang🇨🇳 · T. G. Steele🇨🇦 · Hong-Ying Jin🇨🇳 · Zhuo-Ran Huang🇨🇳

    In this paper, we reanalyze the $I=0$ scalar channel with the improved Monte-Carlo based QCD sum rules, which combines the rigorous Hölder-inequality-determined sum rule window and a two Breit-Wigner type resonances parametrization for the phenomenological spectral density that satisfies the the low-energy theorem for the scalar form factor. Considering the uncertainties of the QCD parameters and the experimental masses and widths of the scalar resonances $\sigma$ and $f_0(980)$, we obtain a prediction for light quark mass $m_q(2\text{GeV})$ = $\frac{1}{2}(m_u(2\text{GeV})$ + $m_d(2\text{GeV}))$ = $4.7_{-0.7}^{+0.8}\text{MeV}$, which is consistent with the PDG (Particle Data Group) value and QCD sum rule determinations in the pseudoscalar channel. This agreement provides a consistent framework connecting QCD sum rules and low-energy hadronic physics. We also obtain the decay constants of $\sigma$ and $f_0(980)$ at 2 GeV, which are approximately $0.64-0.83$ GeV and $0.40-0.48$ GeV respectively.

    hep-phPRD(2017)·9 citations
16. 16*

    A possibility on prohibition of Higgs mass by the extended Lorentz transformation in noncommutative geometry

    Masaki J. S. Yang🇯🇵

    In this letter, we propose the extended Lorentz transformation in noncommutative geometry, as a possibility on prohibition of the Higgs mass. Since it is difficult to build the symmetry between the connections $A_{\mu }$ and $H$, the transformation is defined for the differential two-forms. The parameter of the transformation $\omega$ changes a two-form into other two-forms. Comparing the coefficients of the two-forms, the transformations are translated to those of the product fields $F_{\mu \nu },D_{\mu }H$ and $H{H}^{†}$. It shows the invariance of the bosonic Lagrangian explicitly.

    hep-phhep-th1 citation
17. 17*

    The $B-L$ Scotogenic Models for Dirac Neutrino Masses

    Weijian Wang🇨🇳 · Ronghui Wang🇨🇳 · Zhi-Long Han🇨🇳 · Jin-Zhong Han🇨🇳

    We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of $U(1{)}_{B-L}$ extensions of standard model. It is indicated that the total number of intermediate fermion singlets is uniquely fixed by anomaly free condition and the new particles may have exotic $B-L$ charges so that the direct SM Yukawa mass term ${\bar{\nu }}_L{\nu }_R\overline{{\varphi }^0}$ and the Majorana mass term $(m_N/2)\overline{{\nu }_R^C}{\nu }_R$ are naturally forbidden. After the spontaneous breaking of $U(1{)}_{B-L}$ symmetry, the discrete $Z_2$ or $Z_3$ symmetry appears as the residual symmetry and give rise to the stability of intermediated fields as DM candidate. Phenomenological aspects of lepton flavor violation, DM, leptogenesis and LHC signatures are discussed.

    hep-phEPJC(2017)·85 citations
18. 18*

    Predictions for the neutrino parameters in the minimal gauged U(1)${}_{L_{\mu }-L_{\tau }}$ model

    Kento Asai🇯🇵 · Koichi Hamaguchi🇯🇵 · Natsumi Nagata🇯🇵

    We study the structure of the neutrino mass matrix in the minimal gauged U(1)${}_{L_{\mu }-L_{\tau }}$ model, where three right-handed neutrinos are added to the Standard Model in order to obtain non-zero masses for active neutrinos. Because of the U(1)${}_{L_{\mu }-L_{\tau }}$ gauge symmetry, the structure of both Dirac and Majorana mass terms of neutrinos is tightly restricted. In particular, the inverse of the neutrino mass matrix has zeros in the $(\mu ,\mu )$ and $(\tau ,\tau )$ components, namely, this model offers a symmetric realization of the so-called two-zero-minor structure in the neutrino mass matrix. Due to these constraints, all the CP phases-the Dirac CP phase $\delta$ and the Majorana CP phases ${\alpha }_2$ and ${\alpha }_3$-as well as the mass eigenvalues of the light neutrinos $m_i$ are uniquely determined as functions of the neutrino mixing angles ${\theta }_{12}$, ${\theta }_{23}$, and ${\theta }_{13}$, and the squared mass differences $\Delta m_{21}^2$ and $\Delta m_{31}^2$. We find that this model predicts the Dirac CP phase $\delta$ to be $\delta \simeq 1.59\pi$-$1.70\pi$ ($1.54\pi$-$1.78\pi$), the sum of the neutrino masses to be ${\sum }_i{m}_i\simeq 0.14$-0.22 eV ($0.12$-0.40 eV), and the effective mass for the neutrinoless double beta decay to be $⟨m_{\beta \beta }⟩\simeq 0.024$-0.055 eV ($0.017$-0.12 eV) at $1\sigma$ ($2\sigma$) level, which are totally consistent with the current experimental limits. These predictions can soon be tested in future neutrino experiments. Implications for leptogenesis are also discussed.

    hep-phhep-exEPJC(2017)·85 citations
19. 19*

    $X(4260)$ Revisited: A Coupled Channel Perspective

    Yu Lu🇨🇳 · Muhammad Naeem Anwar🇨🇳 · Bing-Song Zou🇨🇳

    We calculate the probabilities of various charmed meson molecules for $X(4260)$ under the framework of ${}^3{P}_0$ model. The results indicate that even though heavy quark spin symmetry forbids $S$ wave coupling of $D_1\bar{D}$ to the ${}^3{S}_1$ charmonia ($\psi (nS)$), the $D$ wave coupling is allowed and not negligible. Under this symmetry, the $D_1\bar{D}$ can couple to ${}^3{D}_1$ charmonia ($\psi (nD)$) via both $S$ and $D$ wave, and the overall coupling is around three times larger than that of $\psi (nS)$. The $X(4260)$ cannot be a pure molecule but a mixture of a charmonium and various charmed meson components. Since the $D_1\bar{D}$ couples strongly to $\psi (nD)$, our results suggest that in the $D_1\bar{D}$ molecular picture, the charmonium core of $X(4260)$ is $\psi (nD)$ instead of $\psi (nS)$. As a result, the experimental fact that the $R$ ratio has a dip around 4.26 GeV can be understood in the $D_1\bar{D}$ molecular picture of the $X(4260)$.

    hep-phPRD(2017)·27 citations
20. 20*

    New effects of non-standard self-interactions of neutrinos in a supernova

    Anirban Das🇮🇳 · Amol Dighe🇮🇳 · Manibrata Sen🇮🇳

    Neutrino self-interactions are known to lead to non-linear collective flavor oscillations in a core-collapse supernova. We point out new possible effects of non-standard self-interactions (NSSI) of neutrinos on flavor conversions in a two-flavor framework. We show that, for a single-energy neutrino-antineutrino ensemble, a flavor instability is generated even in normal hierarchy for large enough NSSI. Using a toy model for the neutrino spectra, we show that flavor-preserving NSSI lead to pinching of spectral swaps, while flavor-violating NSSI cause swaps to develop away from a spectral crossing or even in the absence of a spectral crossing. Consequently, NSSI could give rise to collective oscillations and spectral splits even during neutronization burst, for both hierarchies.

    hep-phastro-ph.HEastro-ph.SRJCAP(2017)·72 citations
21. 21*

    Charged lepton flavour violation from low scale seesaw neutrinos

    V. De Romeri🇪🇸 · M.J. Herrero🇪🇸 · X. Marcano🇪🇸 · F. Scarcella🇮🇹

    In the work presented here, we have studied the impact of right handed neutrinos, which are introduced to account for the evidence of neutrino masses, on charged lepton flavour violating observables. In particular, we have focused on the loop induced decays of the Z boson into two leptons of different flavour. We have performed a numerical study of the rates predicted for these processes within the Inverse Seesaw model, specifically considering scenarios where $\mu -e$ transitions are suppressed. Our conclusion, after comparison with the most relevant experimental constraints, is that branching ratios as large as $10^{-7}$ can be predicted in the $\tau -\mu$ or $\tau -e$ channels, together with heavy neutrinos having masses of the TeV order. Such rates could be accessible at next generation colliders.

    hep-phPoS(2017)·1 citation
22. 22*

    Flavour symmetric connections with CLFV

    Ye-Ling Zhou🇬🇧

    Flavons are crucial for understanding lepton mixing in models with non-Abelian discrete symmetries. They also result in charged lepton flavour violation (CLFV) via the couplings with leptons. I emphasise that the flavon-triggered CLFV succeeds strong connections with lepton flavour mixing. Relations between branching ratios of CLFV decays and mixing angles are discussed, and CLFV sum rules are obtained. Flavons with masses around hundreds of GeV are consistent by current CLFV measurements.

    hep-ph0 citations
23. 23*

    Are there near-threshold Coulomb-like Baryonia?

    Li-Sheng Geng🇨🇳 · Jun-Xu Lu🇨🇳 · Manuel Pavon Valderrama🇨🇳 · Xiu-Lei Ren🇨🇳

    The ${\Lambda }_c(2590){\Sigma }_c$ system can exchange a pion near the mass-shell. Owing to the opposite intrinsic parity of the ${\Lambda }_c(2590)$ and ${\Sigma }_c$, the pion is exchanged in S-wave. This gives rise to a Coulomb-like force that might be able to bind the system. If one takes into account that the pion is not exactly on the mass shell, there is a shallow S-wave state, which we generically call the $Y_{cc}(5045)$ and $Y_{c\bar{c}}(5045)$ for the ${\Lambda }_c(2590){\Sigma }_c$ and ${\Lambda }_c(2590){\bar{\Sigma }}_c$ systems respectively. For the baryon-antibaryon case this Coulomb-like force is independent of spin: the $Y_{c\bar{c}}(5045)$ baryonia will appear either in the spin $S=0$ or $S=1$ configurations with G-parities $G=(-1{)}^{L+S+1}$. For the baryon-baryon case the Coulomb-like force is attractive in the spin $S=0$ configuration, for which a doubly charmed molecule is expected to form near the threshold. This type of spectrum might be very well realized in other molecular states composed of two opposite parity hadrons with the same spin and a mass difference close to that of a pseudo-Goldstone boson, of which a few examples include the $\Lambda (1405)N$, $\Lambda (1520){\Sigma }^{\ast }$, $\Xi (1690)\Sigma$, $D_{s0}^{\ast }(2317)D$ and $D_{s1}^{\ast }(2460)D^{\ast }$ molecules.

    hep-phhep-exnucl-thPRD(2018)·6 citations
24. 24*

    Study of the $K_1(1270)-K_1(1400)$ mixing in the decays $B\to J/\Psi K_1(1270),J/\Psi K_1(1400)$

    Zhi-Qing Zhang🇨🇳 · Hongxia Guo🇨🇳 · Si-Yang Wang🇨🇳

    We studied the B meson decays $B\to J/\Psi K_1(1270,1400)$ in the pQCD approach beyond the leading order. With the vertex corrections and the NLO Wilson coefficients included, the branching ratios of the considered decays are $Br(B^{+}\to J/\Psi K_1(1270{)}^{+})=1.76_{-0.69}^{+0.65}\times 10^{-3},Br(B^{+}\to J/\Psi K_1(1400{)}^{+})=7.03_{-2.52}^{+2.70}\times 10^{-4}$, and $Br(B^0\to J/\Psi K_1(1270{)}^0)=(1.63_{-0.64}^{+0.60})\times 10^{-3}$ with the mixing angle ${\theta }_{K_1}=33^{\circ }$, which can agree well with the data or the present experimental upper limit within errors. So we support the opinion that ${\theta }_{K_1}\sim 33^{\circ }$ is much more favored than $58^{\circ }$. Furthermore, we also give the predictions for the polarization fractions, direct CP violations from the different polarization components, the relative phase angles for the considered decays with the mixing angle ${\theta }_{K_1}=33^{\circ }$ and $58^{\circ }$, respectively. The direct CP violations of the two charged decays $B^{+}\to J/\Psi K_1(1270,1400{)}^{+}$ are very small $(10^{-4}\sim 10^{-5})$, because there is no weak phase until up to $\mathcal{O}({\lambda }^4)$ with the Wolfenstein parameter $\lambda =0.22537$. These results can be tested at the running LHCb and forthcoming Super-B experiments.

    hep-phEPJC(2018)·13 citations
25. 25*

    Constructing new pseudoscalar meson nonets with the observed $X(2100)$, $X(2500)$, and $\eta (2225)$

    Li-Ming Wang🇨🇳 · Si-Qiang Luo🇨🇳 · Zhi-Feng Sun🇨🇳 · Xiang Liu🇨🇳

    Stimulated by the BESIII observation of $X(2100)$, $X(2500)$, and $\eta (2225)$, we try to pin down new pseudoscalar meson nonets including these states. The analysis of mass spectra and the study of strong decays indicate that $X(2120)$ and $\eta (2225)$ associated with $\pi (2070)$ and the predicted kaon $K(2150)$ may form a new pseudoscalar meson nonet. In addition, more experimental data for $X(2100)$ are necessary to determine its structure of nonets. Then, $X(2500)$, $X(2370)$, $\pi (2360)$, and the predicted kaon $K(2414)$ can be grouped into another new nonet. These assignments to the discussed pseudoscalar states can be further tested in experiment.

    hep-phhep-exPRD(2017)·22 citations
26. 26*

    A Radiative Neutrino Mass Model with SIMP Dark Matter

    Shu-Yu Ho🇺🇸 · Takashi Toma🇩🇪 · Koji Tsumura🇯🇵

    We propose the first viable radiative seesaw model, in which the neutrino masses are induced radiatively via the two-loop Feynman diagram involving Strongly Interacting Massive Particles (SIMP). The stability of SIMP dark matter (DM) is ensured by a ${\mathbb{Z}}_5$ discrete symmetry, through which the DM annihilation rate is dominated by the $3\to 2$ self-annihilating processes. The right amount of thermal relic abundance can be obtained with perturbative couplings in the resonant SIMP scenario, while the astrophysical bounds inferred from the Bullet cluster and spherical halo shapes can be satisfied. We show that SIMP DM is able to maintain kinetic equilibrium with thermal plasma until the freeze-out temperature via the Yukawa interactions associated with neutrino mass generation.

    hep-phJHEP(2017)·32 citations
27. 27*

    A proposal to avoid the ambiguity in the identification of the scale energy parameter ${\tilde{Q}}^2$ of the PDFs in the $Z$-production in $eP$-dis

    M. Gómez-Bock🇲🇽 · W. Gonzalez🇲🇽 · L. López-Lozano🇲🇽 · A. Rosado🇲🇽

    We discuss $Z$ -production in the deep inelastic process $e+P\to e+Z+X$ in the context of the Standard Model using the Parton Model. In contrast to the deep inelastic $eP$-scattering ($e+P\to e+X$), where the choice of ${\tilde{Q}}^2$ is unambiguous, in this case is not clear since the momentum transfer square, at the quark level, depends on the reaction mechanism. Our aim in this work is to show that the total cross section depends strongly on the prescription used for the scale parameter ${\tilde{Q}}^2$ and on a different option that we have taken for making the convolution of the parton distribution functions and the amplitude of the quark processes. We present results for the total cross section as a function of the total energy $\sqrt{s}$ of the system $eP$, in the range $300\le \sqrt{s}\le 1300$ GeV. We find differences of up to 25\% in the rates of the total cross section for the different prescriptions that we have taken, for $\sqrt{s}\approx 1300$ GeV, which is the expected maximal total energy of the system $eP$ to be reached at the LHeC. Taking an integrated luminosity of $a{b}^{-1}$, such a difference (25\%) corresponds to $\approx 10^4$ produced $Z$ bosons. Finally, we propose to modify slightly the Parton Model in order to do a simple and practical prescription for the calculation without ambiguities of the $Z$-production in the deep inelastic $eP$ scattering.

    hep-ph0 citations
28. 28*

    NLO QCD+EW predictions for $2\ell 2\nu$ diboson signatures at the LHC

    S. Kallweit🇨🇭 · J. M. Lindert🇬🇧 · S. Pozzorini🇨🇭 · M. Schonherr🇨🇭

    We present next-to-leading order (NLO) calculations including QCD and electroweak (EW) corrections for $2\ell 2\nu$ diboson signatures with two opposite-charge leptons and two neutrinos. Specifically, we study the processes $pp\to e^{+}{\mu }^{-}{\nu }_e{\bar{\nu }}_{\mu }$ and $pp\to e^{+}{e}^{-}\nu \bar{\nu }$, including all relevant off-shell diboson channels, $W^{+}{W}^{-}$, $ZZ$, $\gamma Z$, as well as non-resonant contributions. Photon-induced processes are computed at NLO EW, and we discuss subtle differences related to the definition and the renormalisation of the coupling $\alpha$ for processes with initial- and final-state photons. All calculations are performed within the automated Munich/Sherpa+OpenLoops frameworks, and we provide numerical predictions for the LHC at 13 TeV. The behaviour of the corrections is investigated with emphasis on the high-energy regime, where NLO EW effects can amount to tens of percent due to large Sudakov logarithms. The interplay between $WW$ and $ZZ$ contributions to the same-flavour channel, $pp\to e^{+}{e}^{-}\nu \bar{\nu }$, is discussed in detail, and a quantitative analysis of photon-induced contributions is presented. Finally, we consider approximations that account for all sources of large logarithms, at high and low energy, by combining virtual EW corrections with a YFS soft-photon resummation or a QED parton shower.

    hep-phhep-exJHEP(2017)·120 citations
29. 29*

    Dark Photon Decay Beyond The Euler-Heisenberg Limit

    Samuel D. McDermott🇺🇸 · Hiren H. Patel🇺🇸 · Harikrishnan Ramani🇺🇸

    We calculate the exact width for a dark photon decaying to three photons at one loop order for dark photon masses m' below the e+e- production threshold of 2m_e. We find substantial deviations from previous results derived from the lowest order Euler-Heisenberg effective Lagrangian in the range m_e < m' < 2m_e, where higher order terms in the derivative expansion are nonnegligible. This mass range is precisely where the three photon decay takes place on cosmologically relevant timescales. Our improved analysis opens a window for dark photons in the range 850 keV < m' < 2m_e, 10^-5 < epsilon < 10^-4.

    hep-phastro-ph.HEhep-thPRD(2018)·58 citations
30. 30*

    An Original Mechanism for the Acceleration of Ultra-High-Energy Cosmic Rays

    Damiano Caprioli (University of Chicago)🇺🇸

    We suggest that ultra-high-energy (UHE) cosmic rays (CRs) may be accelerated in ultra-relativistic flows via a one-shot mechanism, the "espresso" acceleration, in which already-energetic particles are generally boosted by a factor of $\sim {\Gamma }^2$ in energy, where $\Gamma$ is the flow Lorentz factor. More precisely, we consider blazar-like jets with $\Gamma \gtrsim 30$ propagating into a halo of "seed" CRs produced in supernova remnants, which can accelerate UHECRs up to $10^{20}$\,eV. Such a re-acceleration process naturally accounts for the chemical composition measured by the Pierre Auger Collaboration, which resembles the one around and above the knee in the CR spectrum, and is consistent with the distribution of potential sources in the local universe, particularly intriguing is the coincidence of the powerful blazar Mrk 421 with the hotspot reported by the Telescope Array Collaboration.

    ↳ astro-ph.HEastro-ph.COhep-phNucl.Part.Phys.Proc.(2018)·4 citations
31. 31*

    The production of primordial $J/\psi$ in p+p and relativistic heavy-ion collisions

    Taesoo Song🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪

    $J/\psi$ observables of p+p collisions at $\sqrt{s}=$ 200 GeV and 2.76 TeV are calculated using the PYTHIA event generator for the production of $c$ and $\bar{c}$ and the Wigner density formalism. The charm quark momentum from PYTHIA is tuned in such a way that the transverse momentum and rapidity distribution correspond to the Fixed-Order Next-to-Leading Logarithm (FONLL) calculations and hence to the experimental data for open charm mesons. Using the Wigner density of the charmonium wave function we calculate for each charm quark pair the probability to form a charmonium. As a result, the experimental data on the total $J/\psi$ yield, its rapidity and transverse momentum distribution as well as the fractions of feed-down from excited states of charmonium are reproduced. Applying the same approach to relativistic heavy-ion collisions, we find, if quark gluon plasma (QGP) effects are ignored, a considerable enhancement of the primordial $J/\psi$'s.

    ↳ nucl-thhep-phPRC(2017)·30 citations
32. 32*

    Multistage Monte-Carlo simulation of jet modification in a static medium

    JETSCAPE Collaboration: Shanshan Cao🇺🇸 · Chanwook Park🇨🇦 · R. Alex Barbieri🇺🇸 · Steffen A. Bass🇺🇸 · Dennis Bazow🇺🇸 · Jonah Bernhard🇺🇸 · Jacob Coleman🇺🇸 · Rainer Fries🇺🇸 · Charles Gale🇨🇦 · Yayun He🇨🇳 · Ulrich Heinz🇺🇸 · Barbara V. Jacak🇺🇸 and 21 other authors

    The modification of hard jets in an extended static medium held at a fixed temperature is studied using three different Monte-Carlo event generators (LBT, MATTER, MARTINI). Each event generator contains a different set of assumptions regarding the energy and virtuality of the partons within a jet versus the energy scale of the medium, and hence, applies to a different epoch in the space-time history of the jet evolution. For the first time, modeling is developed where a jet may sequentially transition from one generator to the next, on a parton-by-parton level, providing a detailed simulation of the space-time evolution of medium modified jets over a much broader dynamic range than has been attempted previously in a single calculation. Comparisons are carried out for different observables sensitive to jet quenching, including the parton fragmentation function and the azimuthal distribution of jet energy around the jet axis. The effect of varying the boundary between different generators is studied and a theoretically motivated criterion for the location of this boundary is proposed. The importance of such an approach with coupled generators to the modeling of jet quenching is discussed.

    ↳ nucl-thhep-phnucl-exPRC(2017)·112 citations
33. 33*

    Casimir scaling and Yang-Mills glueballs

    Deog Ki Hong🇰🇷 · Jong-Wan Lee🇰🇷 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧

    We conjecture that in Yang-Mills theories the ratio between the ground-state glueball mass squared and the string tension is proportional to the ratio of the eigenvalues of quadratic Casimir operators in the adjoint and the fundamental representations. The proportionality constant depends on the dimension of the space-time only, and is henceforth universal. We argue that this universality, which is supported by available lattice results, is a direct consequence of area-law confinement. In order to explain this universal behaviour, we provide three analytical arguments, based respectively on a Bethe-Salpeter analysis, on the saturation of the scale anomaly by the lightest scalar glueball and on QCD sum rules, commenting on the underlying assumptions that they entail and on their physical implications.

    ↳ hep-thhep-lathep-phPLB(2017)·25 citations
34. 34*

    The Hyper-Kamiokande Experiment

    Masashi Yokoyama (for the Hyper-Kamiokande Proto-collaboration)🇯🇵

    Hyper-Kamiokande (HK) is a next generation large water Cherenkov detector to be built in Japan, based on the highly successful Super-Kamiokande detector. HK will offer a broad science program such as neutrino oscillation studies, proton decay searches, and neutrino astrophysics with unprecedented sensitivities. This paper describes the overview and physics potential of HK.

    ↳ hep-exhep-phphysics.ins-det40 citations
35. 35*

    Charge asymmetry in elastic scattering of massive leptons on protons

    O. Koshchii🇺🇸 · A. Afanasev🇺🇸

    The charge asymmetry due to higher-order QED corrections in elastic lepton-proton scattering is estimated without employing the ultrarelativistic approximation. Our calculation is performed by generalizing the soft-photon approximation approach suggested by Tsai. Corresponding loop integrals that take a form of Passarino-Veltman scalar three-point functions are calculated analytically without neglecting the mass of the lepton. Our results provide model-independent charge asymmetry predictions for scattering of unpolarized and massive leptons on proton targets. These predictions can be used in corresponding experiments to determine the contribution coming from model-dependent hard two-photon exchange processes.

    ↳ nucl-thhep-phPRD(2017)·32 citations
36. 36*

    Laminar and turbulent dynamos in chiral magnetohydrodynamics-I: Theory

    I. Rogachevskii🇮🇱 · O. Ruchayskiy🇩🇰 · A. Boyarsky🇳🇱 · J. Fröhlich🇨🇭 · N. Kleeorin🇮🇱 · A. Brandenburg🇺🇸 · J. Schober🇸🇪

    The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right- and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma (\emph{chiral magnetic effect}). We present a self-consistent treatment of the \emph{chiral MHD equations}, which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that the chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the large-scale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark--gluon plasma.

    ↳ physics.plasm-phastro-ph.COastro-ph.HEhep-ph+1ApJ(2017)·102 citations
37. 37*

    21 cm Angular Power Spectrum from Minihalos as a Probe of Primordial Spectral Runnings

    Toyokazu Sekiguchi🇰🇷 · Tomo Takahashi🇯🇵 · Hiroyuki Tashiro🇯🇵 · Shuichiro Yokoyama🇯🇵

    Measurements of 21 cm line fluctuations from minihalos have been discussed as a powerful probe of a wide range of cosmological models. However, previous studies have taken into account only the pixel variance, where contributions from different scales are integrated. In order to sort out information from different scales, we formulate the angular power spectrum of 21 cm line fluctuations from minihalos at different redshifts, which can enhance the constraining power enormously. By adopting this formalism, we investigate expected constraints on parameters characterizing the primordial power spectrum, particularly focusing on the spectral index $n_s$ and its runnings ${\alpha }_s$ and ${\beta }_s$. We show that future observations of 21 cm line fluctuations from minihalos, in combination with cosmic microwave background, can potentially probe these runnings as ${\alpha }_s\sim \mathcal{O}(10^{-3})$ and ${\beta }_s\sim \mathcal{O}(10^{-4})$. Its implications to the test of inflationary models are also discussed.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·25 citations
38. 38*

    Hadron Production Experiments

    Yoshikazu Nagai🇺🇸

    Precise prediction of the neutrino flux is a key ingredient to achieving the physics goals of accelerator-based neutrino experiments. In modern accelerator-based neutrino experiments, neutrino beams are created by colliding protons with a nuclear target. Secondary hadrons are produced in these collisions, and their decays contribute to the neutrino flux. The hadron production is the leading systematic uncertainty source on the neutrino flux prediction; therefore its precise measurement is desirable. In these proceedings, review of recent hadron production measurements and the latest results from the NA61/SPS Heavy Ion and Neutrino Experiment (NA61/SHINE) are presented. In addition, plans of NA61/SHINE hadron production measurements for the next generation neutrino experiments and NA61/SHINE physics program extension beyond 2020 are discussed.

    ↳ hep-exhep-phphysics.ins-det0 citations
39. 39*

    Discovery potential for directional Dark Matter detection with nuclear emulsions

    N. Agafonova🇷🇺 · A. Aleksandrov🇮🇹 · A. Anokhina🇷🇺 · T. Asada🇯🇵 · V.V. Ashikhmin🇷🇺 · I. Bodnarchuk🇷🇺 · A. Buonaura🇮🇹 · M. Chernyavskii🇷🇺 · A. Chukanov🇷🇺 · N. D'Ambrosio🇮🇹 · G. De Lellis🇮🇹 · A. Di Crescenzo🇮🇹 and 44 other authors

    Direct Dark Matter searches are nowadays one of the most fervid research topics with many experimental efforts devoted to the search for nuclear recoils induced by the scattering of Weakly Interactive Massive Particles (WIMPs). Detectors able to reconstruct the direction of the nucleus recoiling against the scattering WIMP are opening a new frontier to possibly extend Dark Matter searches beyond the neutrino background. Exploiting directionality would also prove the galactic origin of Dark Matter with an unambiguous signal-to-background separation. Indeed, the angular distribution of recoiled nuclei is centered around the direction of the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we present the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and of optical read-out systems reaching unprecedented nanometric resolution.

    ↳ astro-ph.COhep-phphysics.ins-detEPJC(2018)·55 citations
40. 40*

    Hidden Simplicity of the Gravity Action

    Clifford Cheung🇺🇸 · Grant N. Remmen🇺🇸

    We derive new representations of the Einstein-Hilbert action in which graviton perturbation theory is immensely simplified. To accomplish this, we recast the Einstein-Hilbert action as a theory of purely cubic interactions among gravitons and a single auxiliary field. The corresponding equations of motion are the Einstein field equations rewritten as two coupled first-order differential equations. Since all Feynman diagrams are cubic, we are able to derive new off-shell recursion relations for tree-level graviton scattering amplitudes. With a judicious choice of gauge fixing, we then construct an especially compact form for the Einstein-Hilbert action in which all graviton interactions are simply proportional to the graviton kinetic term. Our results apply to graviton perturbations about an arbitrary curved background spacetime.

    ↳ hep-thgr-qchep-phJHEP(2017)·70 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.