Thu·Aug 6, 2015Thursday·August 6, 2015

1. 01*

   Leptogenesis from left-handed neutrino production during axion inflation

   Peter Adshead🇺🇸 · Evangelos I. Sfakianakis🇺🇸

   We propose that the observed matter-antimatter asymmetry can be naturally produced as a byproduct of axion-driven slow-roll inflation by coupling the axion to standard-model neutrinos. We assume that GUT scale right-handed neutrinos are responsible for the masses of the standard model neutrinos and that the Higgs field is light during inflation and develops a Hubble scale vacuum expectation value (VEV). In this set up, the rolling axion generates a helicity asymmetry in standard-model neutrinos. Following inflation, this helicity asymmetry becomes equal to a net lepton number as the Higgs VEV decays and is partially re-processed by the $SU(2{)}_L$ sphaleron into a net baryon number.

   hep-phastro-ph.COPRL(2016)·56 citations
2. 02*

   Superworld without Supersymmetry

   Shreyashi Chakdar🇺🇸 · Kirtiman Ghosh🇺🇸 · S. Nandi🇺🇸

   It is a possibility that the superworld (supersymmetric partners of our world) does exist without supersymmetry. The two worlds are being distinguished by an unbroken discrete $Z_2$ symmetry (similar to R-parity in supersymmetry). We lose the solution to the hierarchy problem. However, such a scenario has several motivations. For example, the lightest neutral superworld particle will be a candidate for dark matter. The other being, as in supersymmetry, it is possible to achieve gauge coupling unification. One major difference with the supersymmetric theory is that such a theory is much more general since it is not constrained by supersymmetry. For example, some of the gauge couplings connecting the Standard Model particles with the superpartners now become free Yukawa couplings. As a result, the final state signals as well as the limits on the superworld particles can be modified both qualitatively and quantitatively. The reach for these superworld particles at the Large Hadron Collider (LHC) can be much higher than the superpartners, leading to the increased possibility of discovering new physics at the LHC.

   hep-phPLB(2016)·0 citations
3. 03*

   Formation of hidden-charm pentaquarks in photon-nucleon collisions

   V. Kubarovsky🇺🇸 · M.B. Voloshin🇺🇸

   The cross section for formation in $\gamma +p$ collisions of the recently found hidden-charm pentaquark states $P_c(4380)$ and $P_c(4450)$ is discussed and estimated. The studies of these resonances in photon beam experiments can be complementary to those in the LHCb experiment setting, and may be more advantageous for measurement of their additional decay channels. It is pointed out that both the relative importance of such decays and the yield of the resonances in the $\gamma +p$ collisions are sensitive to the internal dynamics of the pentaquarks and can resolve between theoretical models. Specific numerical estimates are discussed within a simple `baryocharmonium' model, where the the observed $P_c$ resonances are composites of $J/\psi$ and excited nucleon states with the quantum numbers of $N(1440)$ and $N(1520)$.

   hep-phhep-exPRD(2015)·174 citations
4. 04*

   Fermion production during and after axion inflation

   Peter Adshead🇺🇸 · Evangelos I. Sfakianakis🇺🇸

   We study derivatively coupled fermions in axion-driven inflation, specifically $m_{\varphi }^2{\varphi }^2$ and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.

   hep-phastro-ph.COJCAP(2015)·109 citations
5. 05*

   Light-by-light-type corrections to the muon anomalous magnetic moment at four-loop order

   Alexander Kurz🇩🇪 · Tao Liu🇩🇪 · Peter Marquard🇩🇪 · Alexander V. Smirnov🇷🇺 · Vladimir A. Smirnov🇷🇺 · Matthias Steinhauser🇩🇪

   The numerically dominant QED contributions to the anomalous magnetic moment of the muon stem from Feynman diagrams with internal electron loops. We consider such corrections and present a calculation of the four-loop light-by-light-type corrections where the external photon couples to a closed electron or muon loop. We perform an asymptotic expansion in the ratio of electron and muon mass and reduce the resulting integrals to master integrals which we evaluate using analytical and numerical methods. We confirm the results present in the literature which are based on different computational methods.

   hep-phPRD(2015)·42 citations
6. 06*

   Dark Matter in Leptophilic Higgs Models After the LHC Run-I

   Matthew R. Buckley🇺🇸 · David Feld🇺🇸

   We examine the leptophilic two Higgs doublet model with fermionic dark matter, considering the range of experimental constraints on the Higgs sector. The measurements of the 125 GeV Higgs from the LHC Run-I allow us to focus on those remaining processes that may play an important role at colliders. We find that the leptophilic model allows for a much lighter Higgs than in other two-Higgs models, although discovery at the LHC will be difficult. Adding a dark matter sector motivated by supersymmetric extensions of the leptophilic model, we find the existing parameter space can accommodate constraints from direct detection and the invisible widths of the Higgs and $Z$, while also fitting the Galactic Center gamma ray excess reported by analyses of Fermi-LAT data. We also discuss the status of the fully supersymmetric version of such models, which include four Higgs doublets and a natural dark matter candidate.

   hep-phPRD(2015)·10 citations
7. 07*

   Higgs boson pair production: top quark mass effects at NLO and NNLO

   Jonathan Grigo🇩🇪 · Jens Hoff🇩🇪 · Matthias Steinhauser🇩🇪

   We compute next-to-next-to-leading order QCD corrections to the gluon-induced production cross section of Higgs boson pairs in the large top quark mass limit using the soft-virtual approximation. In the limit of infinitely-heavy top quark we confirm the results in the literature. We add two more expansion terms in the inverse top quark mass to the $M_t\to \infty$ result. Since the $1/M_t$ expansion converges poorly, we try to improve on it by factorizing the exact leading order cross section. We discuss two ways of doing that and conclude that the finite top quark mass effects shift the cross section at most by about 10\% at next-to-leading order and by about 5\% at next-to-next-to-leading order.

   hep-phNPB(2015)·139 citations
8. 08*

   The Parton Orbital Angular Momentum: Status and Prospects

   Keh-Fei Liu🇺🇸 · Cedric Lorce🇺🇸

   Theoretical progress on the formulation and classification of the quark and gluon orbital angular momenta (OAM) is reviewed. Their relation to parton distributions and open questions and puzzles are discussed. We give a status report on the lattice calculation of the parton kinetic and canonical OAM and point out several strategies to calculate the quark and gluon canonical OAM on the lattice.

   hep-phhep-latnucl-thEPJA(2016)·46 citations
9. 09*

   Four-loop Standard Model effective potential at leading order in QCD

   Stephen P. Martin🇺🇸

   The leading QCD part of the four-loop contribution to the effective potential for the Standard Model Higgs field is found. As a byproduct, I also find the corresponding contribution to the four-loop beta function of the Higgs self-interaction coupling.

   hep-phPRD(2015)·56 citations
10. 10*

    $J/\psi ({\eta }_c)N$ and ${\rm Y}({\eta }_b)N$ cross sections

    C. W. Xiao🇩🇪 · U.-G. Meißner🇩🇪

    Inspired by the recent findings of the two $P_c^{+}$ states in the $J/\psi p$ mass spectrum at LHCb, we investigate the elastic and inelastic cross sections of the $J/\psi N$, ${\eta }_{c}N$, ${\rm Y}N$ and ${\eta }_{b}N$ channels within the constraints from heavy quark spin and flavour symmetry. The ${\bar{D}}^{(\ast )}{\Sigma }_c^{(\ast )}$ ($B^{(\ast )}{\Sigma }_b^{(\ast )}$) bound states predicted in earlier works should be accessible in elastic and/or inelastic processes of the $J/\psi N$ and/or ${\eta }_{c}N$ (${\rm Y}N$ and/or ${\eta }_{b}N$) interactions.

    hep-phPRD(2015)·68 citations
11. 11*

    Three-loop Neutrino Mass Model with Doubly Charged Particles from Iso-Doublets

    Hiroshi Okada🇹🇼 · Kei Yagyu🇬🇧

    We propose a new type of a three-loop induced neutrino mass model with dark matter candidates which are required for the neutrino mass generation. The smallness of neutrino masses can be naturally explained without introducing super heavy particles, namely, much heavier than a TeV scale and quite small couplings as compared to the gauge couplings. We find that as a bonus, the anomaly of the muon anomalous magnetic moment can simultaneously be explained by loop effects of new particles. In our model, there are doubly charged scalar bosons and leptons from isospin doublet fields which give characteristic collider signatures. In particular, the doubly charged scalar bosons can decay into the same-sign dilepton with its chirality of both right-handed or left- and right-handed. This can be a smoking gun signature to identify our model and be useful to distinguish other models with doubly charged scalar bosons at collider experiments.

    hep-phPRD(2016)·43 citations
12. 12*

    Cosmological and Particle Physics Constraints on a New Non-Abelian SU(3) Gauge Model for Ordinary/Dark Matter Interaction

    O. Oliveira🇵🇹 · C. A. Bertulani🇺🇸 · M. S. Hussein🇧🇷 · W. de Paula🇧🇷 · T. Frederico🇧🇷

    We propose a mirror model for ordinary and dark matter that assumes a new SU(3) gauge group of transformations, as a natural extension of the Standard Model (SM). A close study of big bang nucleosynthesis, baryon asymmetries, cosmic microwave background bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. The cross section for the elastic scattering of a dark proton by an ordinary proton is estimated and compare to the WIMP--nucleon experimental upper bounds. It is observed that all experimental bounds for the various cross sections can be accommodated consistently within the gauge model. We also suggest a way for direct detection of the new gauge boson via one example of a SM forbidden process: $e^{+}+p\to {\mu }^{+}+X$, where $X=\Lambda$ or ${\Lambda }_c$.

    hep-phhep-exnucl-thBraz.J.Phys.(2016)·7 citations
13. 13*

    Pion transverse momentum dependent parton distributions in the Nambu and Jona-Lasinio model

    Santiago Noguera🇪🇸 · Sergio Scopetta🇮🇹

    An explicit evaluation of the two pion transverse momentum dependent parton distributions at leading twist is presented, in the framework of the Nambu-Jona Lasinio model with Pauli-Villars regularization. The transverse momentum dependence of the obtained distributions is generated solely by the dynamics of the model. Using these results, the so called generalized Boer-Mulders shift is studied and compared with recent lattice data. The obtained agreement is very encouraging, in particular because no additional parameter has been introduced. A more conclusive comparison would require a precise knowledge of the QCD evolution of the transverse momentum dependent parton distributions under scrutiny.

    hep-phJHEP(2015)·55 citations
14. 14*

    Invisible Higgs Decay at the LHeC

    Yi-Lei Tang🇨🇳 · Chen Zhang🇨🇳 · Shou-hua Zhu🇨🇳

    The possibility that the 125 GeV Higgs boson may decay into invisible non-standard-model (non-SM) particles is theoretically and phenomenologically intriguing. In this letter we investigate the sensitivity of the Large Hadron Electron Collider (LHeC) to an invisibly decaying Higgs, in its proposed high luminosity running mode. We focus on the neutral current Higgs production channel which offers more kinematical handles than its charged current counterpart. The signal contains one electron, one jet and large missing energy. With a cut-based parton level analysis, we estimate that if the $hZZ$ coupling is at its standard model (SM) value, then assuming an integrated luminosity of $1\text{mbox}{ab}^{-1}$ the LHeC with the proposed 60 GeV electron beam (with $-0.9$ polarization) and 7 TeV proton beam is capable of probing $\mathrm{Br}(h\to E{/}_T)=6\%$ at $2\sigma$ level. Good lepton veto performance (especially hadronic $\tau$ veto) in the forward region is crucial to the suppression of the dominant $Wje$ background. We also explicitly point out the important role that may be played by the LHeC in probing a wide class of exotic Higgs decay processes and emphasize the general function of lepton-hadron colliders in precision study of new resonances after their discovery in hadron-hadron collisions.

    hep-phhep-exPRD(2016)·26 citations
15. 15*

    The Half-composite Two Higgs Doublet Model and the Relaxion

    Oleg Antipin🇮🇹 · Michele Redi🇮🇹

    We study a new confining gauge theory with fermions in a vectorial representation under the SM gauge group that allows for Yukawa interactions with the Higgs. If the fermion masses are smaller than the confinement scale this realizes a type I two Higgs doublet model where a composite Higgs mixes with the elementary Higgs. This class of models interpolates between an elementary and a composite Higgs and has interesting phenomenology with potentially observables effects in collider physics, EDMs and SM couplings but very weak bounds from indirect searches. The very same framework can be used to realize the cosmological relaxation of the electro-weak scale recently discussed in the literature.

    hep-phJHEP(2015)·57 citations
16. 16*

    Small black holes in global AdS spacetime

    Niko Jokela🇫🇮 · Arttu Pönni🇫🇮 · Aleksi Vuorinen🇫🇮

    We study finite temperature correlation functions and quasinormal modes in a strongly coupled conformal field theory holographically dual to a small black hole in global Anti-de Sitter spacetime. Upon variation of the black hole radius, our results smoothly interpolate between known limits corresponding to large black holes and thermal AdS space. This implies that the quantities are continuous functions of energy density in the microcanonical ensemble, thus smoothly connecting the deconfined and confined phases that are separated by a first order phase transition in the canonical description.

    ↳ hep-thgr-qchep-phPRD(2016)·14 citations
17. 17*

    Two-Nucleon Higher Partial-Wave Scattering from Lattice QCD

    Evan Berkowitz🇺🇸 · Thorsten Kurth🇺🇸 · Amy Nicholson🇺🇸 · Balint Joo🇺🇸 · Enrico Rinaldi🇺🇸 · Mark Strother🇺🇸 · Pavlos M. Vranas🇺🇸 · Andre Walker-Loud🇺🇸

    We present a determination of nucleon-nucleon scattering phase shifts for l >= 0. The S, P, D and F phase shifts for both the spin-triplet and spin-singlet channels are computed with lattice Quantum ChromoDynamics. For l > 0, this is the first lattice QCD calculation using the Luscher finite-volume formalism. This required the design and implementation of novel lattice methods involving displaced sources and momentum-space cubic sinks. To demonstrate the utility of our approach, the calculations were performed in the SU(3)-flavor limit where the light quark masses have been tuned to the physical strange quark mass, corresponding to m_pi = m_K ~ 800 MeV. In this work, we have assumed that only the lowest partial waves contribute to each channel, ignoring the unphysical partial wave mixing that arises within the finite-volume formalism. This assumption is only valid for sufficiently low energies; we present evidence that it holds for our study using two different channels. Two spatial volumes of V ~ (3.5 fm)^3 and V ~ (4.6 fm)^3 were used. The finite-volume spectrum is extracted from the exponential falloff of the correlation functions. Said spectrum is mapped onto the infinite volume phase shifts using the generalization of the Luscher formalism for two-nucleon systems.

    ↳ hep-lathep-phnucl-thPLB(2017)·135 citations
18. 18*

    The Effect of Primordial Non-Gaussianities on the Seeds of Super-Massive Black Holes

    Zeinab Sherkatghanad🇨🇦 · Robert H. Brandenberger (McGill University)🇨🇦

    The origin of the seeds which develop into the observed super-massive black holes at high redshifts may be hard to interpret in the context of the standard $\Lambda CDM$ of early universe cosmology based on Gaussian primordial perturbations. Here we consider the modification of the halo mass function obtained by introducing skewness and kurtosis of the primordial fluctuations. We show that such primordial non-Gaussianities constrained by the current observational bounds on the nonlinearity parameters of $f_{NL}$ and $g_{NL}$ are not effective at greatly increasing the number density of seeds which could develop into super-massive black holes at high redshifts. This is to be contrasted with the role which cosmic string loops could play in seeding super-massive black holes.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+13 citations
19. 19*

    Pion and proton form factors in the Regge description of electroproduction $p(e,e^{\prime }{\pi }^{+})n$

    Tae Keun Choi🇰🇷 · Kook Jin Kong🇰🇷 · Byung Geel Yu🇰🇷

    Electroproduction of ${\pi }^{+}$ above the resonance region is analyzed in the Regge model for $\pi +\rho$ exchanges. Importance of the roles of pion and proton form factors in the process is discussed in comparison with existing models of Kaskulov and Mosel, and of Vrancx and Rychebusch. It is shown that the present model with proton form factor of a simple dipole-type yields a better description of DESY and JLab data over those models for high $Q^2$ and $-t$ region up to 5 GeV${}^2$.

    ↳ nucl-thhep-phJ.Korean Phys.Soc.(2015)·11 citations
20. 20*

    Adiabatic Invariance of Oscillons/I-balls

    Masahiro Kawasaki🇯🇵 · Fuminobu Takahashi🇯🇵 · Naoyuki Takeda🇯🇵

    Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or $I$-balls. We prove the adiabatic invariance of the oscillons/$I$-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/$I$-balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/$I$-balls are only quasi-stable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the $I$-balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/$I$-balls is due to the adiabatic invariance.

    ↳ hep-thastro-ph.COcond-mat.softhep-phPRD(2015)·36 citations
21. 21*

    Subleading Terms in the Collinear Limit of Yang-Mills Amplitudes

    Stephan Stieberger🇩🇪 · Tomasz R. Taylor🇺🇸

    For two massless particles i and j, the collinear limit is a special kinematic configuration in which the particles propagate with parallel four-momentum vectors, with the total momentum P distributed as p_i=xP and p_j=(1-x)P, so that s_{ij}=(p_i+p_j)^2=P^2=0. In Yang-Mills theory, if i and j are among N gauge bosons participating in a scattering process, it is well known that the partial amplitudes associated to the (single trace) group factors with adjacent i and j are singular in the collinear limit and factorize at the leading order into N-1-particle amplitudes times the universal, x-dependent Altarelli-Parisi factors. We give a precise definition of the collinear limit and show that at the tree level, the subleading, non-singular terms are related to the amplitudes with a single graviton inserted instead of two collinear gauge bosons. To that end, we argue that in one-graviton Einstein-Yang-Mills amplitudes, the graviton with momentum P can be replaced by a pair of collinear gauge bosons carrying arbitrary momentum fractions xP and (1-x)P.

    ↳ hep-thhep-phPLB(2015)·38 citations
22. 22*

    A short introduction to heavy-ion physics

    Sourendu Gupta🇮🇳

    Heavy-ion collisions provide the only laboratory tests of relativistic quantum field theory at finite temperature. Understanding these is a necessary step in understanding the origins of our universe. These lectures introduce the subject to experimental particle physicists, in the hope that they will be useful to others as well. The phase diagram of QCD is briefly touched upon. Kinematic variables which arise in the collisions of heavy-ions beyond those in the collisions of protons or electrons are introduced. Finally, a few of the signals studied in heavy-ion collisions, and the kind of physics questions which they open up are discussed.

    ↳ nucl-thhep-exhep-phnucl-exCERN-2017-005-SP, pp. 219-238·2 citations
23. 23*

    Effective Single Photon Decay Mode of Positronium Decay via Electroweak Interactions

    Jesús Pérez-Ríos🇺🇸 · Sherwin T. Love🇺🇸

    We consider the decay of positronium to a neutrino-antineutrino accompanied by a single photon. Since the neutrino pair go undetected, this appears as a single photon decay of positronium. These decay channel are mediated through the exchange of the massive $W$ and $Z$ vector bosons of the electroweak interaction. After summing over the various neutrino channels, the standard model calculation yields the rate for such a single photon decay process of ${\Gamma }_{Ps\to \gamma }$ = 1.72 $\times 10^{-19}$ s${}^{-1}$.

    ↳ physics.atom-phhep-phphysics.chem-phquant-phJ.Phys.B(2015)·4 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.