Tue·Dec 27, 2016Tuesday·December 27, 2016

1. 01*

   Electric Dipole Moments in Natural Supersymmetry

   Yuichiro Nakai🇺🇸 · Matthew Reece🇺🇸

   We discuss electric dipole moments (EDMs) in the framework of CP-violating natural supersymmetry (SUSY). Recent experimental results have significantly tightened constraints on the EDMs of electrons and of mercury, and substantial further progress is expected in the near future. We assess how these results constrain the parameter space of natural SUSY. In addition to our discussion of SUSY, we provide a set of general formulas for two-loop fermion EDMs, which can be applied to a wide range of models of new physics. In the SUSY context, the two-loop effects of stops and charginos respectively constrain the phases of $A_t\mu$ and $M_2\mu$ to be small in the natural part of parameter space. If the Higgs mass is lifted to 125 GeV by a new tree-level superpotential interaction and soft term with CP-violating phases, significant EDMs can arise from the two-loop effects of $W$ bosons and tops. We compare the bounds arising from EDMs to those from other probes of new physics including colliders, $b\to s\gamma$, and dark matter searches. Importantly, improvements in reach not only constrain higher masses, but require the phases to be significantly smaller in the natural parameter space at low mass. The required smallness of phases sharpens the CP problem of natural SUSY model building.

   hep-phJHEP(2017)·70 citations
2. 02*

   Triple parton scatterings in proton-nucleus collisions at high energies

   David d'Enterria🇨🇭 · Alexander M. Snigirev🇷🇺

   A generic expression to compute triple parton scattering (TPS) cross sections in high-energy proton-nucleus (pA) collisions is derived as a function of the corresponding single-parton cross sections and an effective parameter encoding the transverse parton profile of the proton. The TPS cross sections are enhanced by a factor of $9A\approx 2000$ in pPb compared to those in proton-nucleon collisions at the same center-of-mass energy. Estimates for triple charm ($c\overline{c}$) and bottom ($b\overline{b}$) production in pPb collisions at LHC and FCC energies are presented based on next-to-next-to-leading order (NNLO) calculations for $c\overline{c},b\overline{b}$ single-parton cross sections. At $\sqrt{s_{NN}}=8.8$ TeV, about 10% of the pPb events have three $c\overline{c}$ pairs produced in separate partonic interactions. At $\sqrt{s_{NN}}=63$ TeV, the pPb cross sections for triple-J$/\psi$ and triple-$b\overline{b}$ are $\mathcal{O}$(1--10 mb). In the most energetic cosmic-ray collisions observed on earth, TPS $c\overline{c}$-pair cross sections equal the total p-Air inelastic cross section.

   hep-phastro-ph.HEhep-exnucl-ex+1EPJC(2018)·33 citations
3. 03*

   Three-body charmless baryonic ${\bar{B}}_s^0$ decays

   C.Q. Geng🇨🇳 · Y.K. Hsiao🇨🇳 · Eduardo Rodrigues🇺🇸

   We study for the first time the three-body charmless baryonic decays ${\bar{B}}_s^0\to \bar{p}\Lambda M^{+}(p\bar{\Lambda }{M}^{-})$, with $M=\pi ,K$. We find that the branching ratios of ${\bar{B}}_s^0\to (\bar{p}\Lambda K^{+}$ and $p\bar{\Lambda }{K}^{-})$ and ${\bar{B}}_s^0\to p\bar{\Lambda }{\pi }^{-}$ are $(5.1\pm 1.1)\times 10^{-6}$ and $(2.8\pm 1.5)\times 10^{-7}$, respectively, which agree with recent experimental results reported by the LHCb collaboration. In addition, we derive the relations \mbox{$\mathcal{B}({\bar{B}}_s^0\to \bar{p}\Lambda K^{+})\simeq (f_K/f_{\pi }{)}^2({\tau }_{B_s^0}/{\tau }_{B^0})\mathcal{B}({\bar{B}}^0\to \bar{p}\Lambda {\pi }^{+})$} and $\mathcal{B}({\bar{B}}_s^0\to p\bar{\Lambda }{\pi }^{-})/\mathcal{B}({\bar{B}}_s^0\to p\bar{\Lambda }{K}^{-})\simeq \mathcal{B}(B^{-}\to p\bar{p}{\pi }^{-})/\mathcal{B}(B^{-}\to p\bar{p}{K}^{-})$ to be confronted to future experimental measurements. The fact that all four processes $B_s^0,{\bar{B}}_s^0\to p\bar{\Lambda }{K}^{-},\bar{p}\Lambda K^{+}$ can occur opens the possibility of decay-time-dependent CP violation measurements in baryonic $B$ decays, something that had not been realised before.

   hep-phhep-exPLB(2017)·15 citations
4. 04*

   The $Z_c(3900)$ peak does not come from the "triangle singularity"

   Qin-Rong Gong🇨🇳 · Jing-Long Pang🇨🇳 · Yu-Fei Wang🇨🇳 · Han-Qing Zheng🇨🇳

   We compare contributions from the triangle diagram and the $D{\bar{D}}^{\ast }$ bubble chain to the processes of $e^{+}{e}^{-}\to J/\psi {\pi }^{+}{\pi }^{-}$ and $e^{+}{e}^{-}\to (D{\bar{D}}^{\ast }{)}^{\mp }{\pi }^{\pm }$. By fitting the $J/\psi \pi$ maximum spectrum and the $D{\bar{D}}^{\ast }$ spectrum, we find that the triangle diagram cannot explain the new data from BESIII Collaboration at center of mass at 4.23GeV and 4.26GeV, simultaneously. On the contrary, the molecular assignment of $Z_c(3900)$ gives a much better description.

   hep-phhep-exEPJC(2018)·37 citations
5. 05*

   The effect of real and virtual photons in the di-lepton channel at the LHC

   Elena Accomando🇬🇧 · Juri Fiaschi🇬🇧 · Francesco Hautmann🇬🇧 · Stefano Moretti🇬🇧 · Claire H. Shepherd-Themistocleous🇬🇧

   We present a study of di-lepton production at the CERN Large Hadron Collider with a particular focus on the contribution resulting from both real and virtual photons in the initial state. We discuss the region of phase space in which the invariant mass of the lepton pair is of the order of several TeV, where searches for new physics phenomena yielding a di-lepton signature are presently carried out. We study both the yield and associated uncertainties for all possible topologies in photon-induced di-lepton production and compare these with what is expected in the standard Drell-Yan channel, where quark-antiquark pairs are responsible for the production of lepton pairs. We analyse the impact of these QED contributions on the expected Standard Model background and on searches for new physics. In this latter case, we use the production of an extra heavy $Z^{\prime }$-boson predicted by the Sequential Standard Model (SSM) as a benchmark process.

   hep-phPLB(2017)·21 citations
6. 06*

   Quarkonium Masses in the N-dimensional Space Using the Analytical Exact Iteration Method

   E. M. Khokha🇪🇬 · M. Abu-Shady🇪🇬 · T. A. Abdel-Karim🇪🇬

   The N-dimensional radial Schrodinger equation with an extended Cornell potential is solved. The analytical exact iteration method is applied. The energy eigenvalues are calculated in the N-dimensional space. The charmonium meson, the bottomonium meson and the bc meson masses are calculated in the N-dimensional space. The special cases are obtained from the general case. The study of the effect of dimensionality number is studied. The mean value of the radius and the mean square velocity of charmonium meson, bottomonium meson, and bc meson are calculated. The present results are improved in comparison with other recent studies and are in good agreement with the experimental data. Therefore, the present method with the present potential gives successfully description of heavy quarkonium properties.

   hep-phInternational Journal of Theoretical and …·9 citations
7. 07*

   Testing Neutrino Mass Models at the LHC and beyond

   P. S. Bhupal Dev🇺🇸

   We briefly review the current status and future prospects of testing the low-scale seesaw models of neutrino mass generation at the energy frontier, with particular emphasis on the ongoing searches at the LHC.

   hep-phhep-exPoS(2016)·3 citations
8. 08*

   Heavy MSSM Higgs Interpretation of the LHC Run I Data

   S. Heinemeyer🇪🇸

   We review that the heavy CP-even MSSM Higgs boson is still a viable candidate to explain the Higgs signal at 125 GeV. This is possible in a highly constrained parameter region, that will be probed by LHC searches for the CP-odd Higgs boson and the charged Higgs boson in the near future. We briefly discuss the new benchmark scenarios that can be employed to maximize the sensitivity of the experimental analysis to this interpretation.

   hep-phPoS(2017)·2 citations
9. 09*

   Dynamical model of antishadowing of the nuclear gluon distribution

   L. Frankfurt (Tel Aviv U. & Penn State U.)🇮🇱 · V. Guzey (St. Petersburg, INT)🇷🇺 · M. Strikman (Penn State U.)🇺🇸

   We explore the theoretical observation that within the leading twist approximation, the nuclear effects of shadowing and antishadowing in non-perturbative nuclear parton distribution functions (nPDFs) at the input QCD evolution scale involve diffraction on nucleons of a nuclear target and originate from merging of two parton ladders belonging to two different nucleons, which are close in the rapidity space. It allows us to propose that for a given momentum fraction $x_P$ carried by the diffractive exchange, nuclear shadowing and antishadowing should compensate each other in the momentum sum rule for nPDFs locally on the interval $\ln (x/x_P)\le 1$. We realize this by constructing an explicit model of nuclear gluon antishadowing, which has a wide support in $x$, $10^{-4}<x<0.2$, peaks at $x=0.05-0.1$ at the level of $\approx 15$\% for ${}^{208}$Pb at $Q_0^2=4$ GeV${}^2$ and rather insignificantly depends on details of the model. We also studied the impact parameter $b$ dependence of antishadowing and found it to be slow.

   hep-phPRC(2017)·20 citations
10. 10*

    Overview on Neutrino Theory and Phenomenology

    Shun Zhou🇨🇳

    In this talk, I give an overview on recent theoretical and phenomenological studies of massive neutrinos. First of all, the present status of neutrino mixing parameters is summarized. The phenomenology of neutrino oscillations is then discussed, and current understanding of lepton flavor mixing is presented. Finally, I consider the seesaw models of neutrino masses and briefly mention the direct searches at the CERN Large Hadron Collider (LHC).

    hep-phNucl.Part.Phys.Proc.(2017)·1 citation
11. 11*

    Relic Right-handed Dirac Neutrinos and Cosmic Neutrino Background

    Shun Zhou🇨🇳

    The PTOLEMY experiment, implementing a $100\mathrm{g}$ surface-deposition tritium target, is promising to detect cosmic neutrino background via ${\nu }_e^{}+{}^3\mathrm{H}\to {}^3\mathrm{He}+e^{-}$. In this talk, I consider a thermal production of right-handed Dirac neutrinos in the early Universe, and investigate their impact on the capture rate of cosmic relic neutrinos at PTOLEMY.

    hep-phPoS(2016)·0 citations
12. 12*

    Gravitational waves from domain walls and their implications

    Kazunori Nakayama🇯🇵 · Fuminobu Takahashi🇯🇵 · Norimi Yokozaki🇯🇵

    We evaluate the impact of domain-wall annihilation on the currently ongoing and planned gravitational wave experiments, including a case in which domain walls experience a frictional force due to interactions with the ambient plasma. We show the sensitivity reach in terms of physical parameters, namely, the wall tension and the annihilation temperature. We find that a Higgs portal scalar, which stabilizes the Higgs potential at high energy scales, can form domain walls whose annihilation produces a large amount of gravitational waves within the reach of the advanced LIGO experiment (O5). Domain wall annihilation can also generate baryon asymmetry if the scalar is coupled to either SU(2)${}_L$ gauge fields or the $(B-L)$ current. This is a variant of spontaneous baryogenesis, but it naturally avoids the isocurvature constraint due to the scaling behavior of the domain-wall evolution. We delineate the parameter space where the domain-wall baryogenesis works successfully and discuss its implications for the gravitational wave experiments.

    hep-phastro-ph.COPLB(2017)·45 citations
13. 13*

    Aspects of fermion dynamics from Lorentz symmetry violation

    Julio Leite🇬🇧

    In this thesis we are interested in understanding how Lorentz symmetry violation can affect some features of fermion dynamics and, perhaps, help to solve some well-known problems in particle physics, such as the origin of neutrino masses and oscillations. Firstly, we consider two Lorentz-Invariance-Violating (LIV) models and investigate the possibility of generating masses and oscillations dynamically for both Dirac and Majorana neutrinos, using non-perturbative methods, such as the Schwinger-Dyson and the effective potential approaches. In our studies, Lorentz symmetric models are extended by the inclusion of higher-order LIV operators, which improve the convergence of loop integrals and introduce a natural mass scale to the theories. We then present how Lorentz invariance can be recovered, for both models, after quantisation, in such a way that the dynamical masses and mixing are the only quantum effects that remain finite. Additionally, we study how matter fields, especially fermions, behave when coupled to two modified gravity models. Such modified gravity models break the 4-dimensional diffeomorphism invariance and, consequently, induce local Lorentz violation. In particular, we consider Horava-Lifshitz gravity, which presents an improved ultraviolet behaviour when compared to General Relativity (GR), and thus addresses a fundamental problem in physics: the non-(perturbative-)renormalisability of the theory of GR. We calculate the LIV one-loop corrections to the matter sector dispersion relations, after integration over graviton components, and show that, by imposing reasonable constraints on the energy scales of our gravity models, our results are consistent with the current bounds on Lorentz symmetry violation.

    hep-phhep-th0 citations
14. 14*

    The possible $B\pi$ molecular state and its radiative decay

    Hong-Wei Ke · Lei Gao · Xue-Qian Li🇨🇳

    Recently, several exotic bosons have been confirmed as multi-quark states, but there are violent disputes about their inner structures, namely if they are molecular states or tetraquarks, or even mixtures of the two structures. It would be interesting to experimentally search for non-strange four-quark states with open charm or bottom which are lighter than ${\Lambda }_c$ or ${\Lambda }_b$. Reasonable arguments indicate that they are good candidates of pure molecular states $D\pi$ or $B\pi$ because pions are the lightest boson. Both $B\pi$ and $D\pi$ bound states do not decay via strong interaction. The $B\pi$ molecule may decay into $B^{\ast }$ by radiating a photon, whereas $D\pi$ molecule can only decay via weak interaction. In this paper we explore the mass spectra of $B\pi$ molecular statesby solving the corresponding B-S equation. Then the rate of radiative decay $|\frac{3}{2},\frac{1}{2}⟩\to B^{\ast }\gamma$ is calculated and our numerical results indicate that the processes can be measured by the future experiment. We also briefly discuss the $D\pi$ case, due to the constraint of the final state phase space, it can only decay via weak interaction.

    hep-phhep-exEPJC(2017)·4 citations
15. 15*

    Planck scale black holes - Theory vs. observations

    Michael Florian Wondrak🇩🇪 · Piero Nicolini🇩🇪 · Marcus Bleicher🇩🇪

    In this paper we present the status of the physics of Planck scale black holes with particular reference to their conjectured production in particle accelerator experiments at the terascale. After reviewing some open issues of fundamental interactions and introducing the physics in the large extra-dimensional scenario, we present the expected signatures left by a microscopic black hole in a particle detector. The final part of the paper is devoted to the latest experimental bounds on the sought black hole signals.

    hep-phhep-thPoS(2017)·3 citations
16. 16*

    Different pole structures in line shapes of the $X(3872)$

    Xian-Wei Kang🇪🇸 · J. A. Oller🇪🇸

    We introduce a near-threshold parameterization that is more general than the effective-range expansion up to and including the effective-range because it can also handle with a near-threshold zero in the $D^0{\bar{D}}^{\ast 0}$ $S$-wave. In terms of it we analyze the CDF data on inclusive $p\bar{p}$ scattering to $J/\psi {\pi }^{+}{\pi }^{-}$, and the Belle and BaBar data on $B$ decays to $KJ/\psi {\pi }^{+}{\pi }^{-}$ and $KD{\bar{D}}^{\ast 0}$ around the $D^0{\bar{D}}^{\ast 0}$ threshold. It is shown that data can be reproduced with similar quality for the $X(3872)$ being a bound {\it and/or} a virtual state. We also find that the $X(3872)$ might be a higher-order virtual-state pole (double or triplet pole), in the limit in which the small $D^{\ast 0}$ width vanishes. Once the latter is restored the corrections to the pole position are non-analytic and much bigger than the $D^{\ast 0}$ width itself. The $X(3872)$ compositeness coefficient in $D^0{\bar{D}}^{\ast 0}$ ranges from nearly 0 up to 1 in the different scenarios.

    hep-phhep-exnucl-thEPJC(2017)·106 citations
17. 17*

    Effective field theories for quantum chromo- and electrodynamics

    Ou Z. Labun🇺🇸

    In this dissertation, I introduce the principles and methods of effective field theory and describe my work in three EFTs: First, in the perturbative QCD region, I use soft collinear effective theory (SCET) to prove that strong interaction soft radiation is universal and to increase the QCD accuracy to next-to-next-tonext- to leading logarithm order for new particle searches in hadron colliders. I also compute a new class of non-perturbative, large logarithmic enhancement arising near the elastic limits of deep inelastic scattering and Drell-Yan processes. Second, in the QCD confinement region, I use heavy hadron chiral perturbation theory to study near-threshold enhancements in the scattering of $D$ and $\pi$ mesons near the threshold for the excited $D$-meson state, $D^{\ast }$, as well as in the scattering of $D$ and $D^{\ast }$ mesons near the threshold for the exotic hadron X(3872). This work provides a clear picture of the hadronic molecule X(3872) and more profound understanding of the nuclear force between hadrons. Finally, inspired by SCET, I construct a new electron-laser effective field theory to describe highly-relativistic electrons traveling in strong laser fields, extract the universal distribution of electrons in strong electromagnetic backgrounds and its evolution in energy from the separated momentum scales of emitted photons and classical radiation, and predict the rate of wide angle photon emission. I conclude with limitations of EFT methods and some perspectives on what new work may be achieved with these EFTs.

    hep-phnucl-th1 citation
18. 18*

    The KLOE-2 Experiment at DAPHNE

    Wojciech Wislicki🇵🇱

    We present recent results obtained by the KLOE-2 Collaboration at the DAPHNE e+e- collider. The first class of results concerns search for dark forces at the scale of 1 GeV in associated production of gamma and the U boson, in search for the Higgsstrahlung and in possible decays of phi into eta and U. The second is in neutral kaon physics, on testing the CPT and Lorentz invariance, and on search for quantum decoherence effects in entangled pairs of kaons. The third class of results concerns precision measurements in hadronic physics at low energy where transition form factors of phi to pseudoscalar mesons pi0 and eta are determined.

    ↳ hep-exhep-phPoS(2017)·0 citations
19. 19*

    Standard Model Mass Spectrum in Inflationary Universe

    Xingang Chen🇺🇸 · Yi Wang🇨🇳 · Zhong-Zhi Xianyu🇺🇸

    We work out the Standard Model (SM) mass spectrum during inflation with quantum corrections, and explore its observable consequences in the squeezed limit of non-Gaussianity. Both non-Higgs and Higgs inflation models are studied in detail. We also illustrate how some inflationary loop diagrams can be computed neatly by Wick-rotating the inflation background to Euclidean signature and by dimensional regularization.

    ↳ hep-thastro-ph.COhep-phJHEP(2017)·133 citations
20. 20*

    Hyperon single-particle potentials from QCD on lattice

    Takashi Inoue · for HAL QCD Collaboration

    We study single-particle potential of hyperons in nuclear medium starting from QCD. First we carry out lattice QCD numerical simulation to 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 hadron masses are nearly physical, e.g. pion mass is 146 MeV, kaon mass is 525 MeV, and nucleon mass is 956 MeV. Then, with some simplifications, we apply the obtained hyperon interactions to the Brueckner-Hartree-Fock theory and calculate single-particle potential of hyperons in nuclear medium $U_Y(\rho ,k)$. For the symmetric nuclear matter at the normal nuclear matter density, we obtain $U_{\Lambda }({\rho }_0,0)=-33$ MeV, $U_{\Sigma }({\rho }_0,0)=+11$ MeV, and $U_{\Xi }({\rho }_0,0)=-6$ MeV. These results are qualitatively compatible with values suggested from experiments. This success is remarkable and encouraging because we are trying to reveal nature of baryon-baryon interactions starting from QCD, and this agreement proves that our approach is essentially correct.

    ↳ hep-lathep-phnucl-exnucl-thPoS(2016)·24 citations

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