Fri·Mar 25, 2016Friday·March 25, 2016

1. 01*

   A Diphoton Resonance from Bulk RS

   Csaba Csaki🇺🇸 · Lisa Randall🇺🇸

   Recent LHC data hinted at a 750 GeV mass resonance that decays into two photons. A significant feature of this resonance is that its decays to any other Standard Model particles would be too low to be detected so far. Such a state has a compelling explanation in terms of a scalar or a pseudoscalar that is strongly coupled to vector states charged under the Standard Model gauge groups. Such a scenario is readily accommodated in bulk RS with a scalar localized in the bulk away from but close to the Higgs. Turning this around, we argue that a good way to find the elusive bulk RS model might be the search for a resonance with prominent couplings to gauge bosons.

   hep-phhep-exhep-thJHEP(2016)·37 citations
2. 02*

   From ${\Xi }_b\to {\Lambda }_b\pi$ to ${\Xi }_c\to {\Lambda }_c\pi$

   Michael Gronau🇮🇱 · Jonathan L. Rosner🇺🇸

   Using a successful framework for describing S-wave hadronic decays of light hyperons induced by a subprocess $s\to u(\bar{u}d)$, we presented recently a model-independent calculation of the amplitude and branching ratio for ${\Xi }_b^{-}\to {\Lambda }_b{\pi }^{-}$ in agreement with a LHCb measurement. The same quark process contributes to ${\Xi }_c^0\to {\Lambda }_c{\pi }^{-}$, while a second term from the subprocess $cs\to cd$ has been related by Voloshin to differences among total decay rates of charmed baryons. We calculate this term and find it to have a magnitude approximately equal to the $s\to u(\bar{u}d)$ term. We argue for a negligible relative phase between these two contributions, potentially due to final state interactions. However, we do not know whether they interfere destructively or constructively. For constructive interference one predicts $\mathcal{B}({\Xi }_c^0\to {\Lambda }_c{\pi }^{-})=(1.94\pm 0.70)\times 10^{-3}$ and $\mathcal{B}({\Xi }_c^{+}\to {\Lambda }_c{\pi }^0)=(3.86\pm 1.35)\times 10^{-3}$. For destructive interference, the respective branching fractions are expected to be less than about $10^{-4}$ and $2\times 10^{-4}$.

   hep-phhep-exPLB(2016)·14 citations
3. 03*

   Superbumps

   Yang Bai🇺🇸 · Joshua Berger🇺🇸

   For a wide range of supersymmetric models, there is a chiral superfield whose scalar and pseudo-scalar have approximately degenerate masses and couplings to Standard Model particles. At colliders, they may show up as "superbumps": a pair of resonances with similar masses and production cross-sections. Observing the superbumps may provide evidence of supersymmetry even without seeing superpartners with a different spin. We present two models which realize the superbump scenario. The first one contains an elementary superfield, 24, under SU(5)_GUT, while the second one is based on the supersymmetric QCD model with N_f = N_c +1 and identifying SU(N_f=5) as SU(5)_GUT. Both models have rich phenomenology including nearly mass-degenerate scalar and pseudo-scalar color octets that appear as three body resonances of two photons and one gluon. We also show that the recent 750 GeV diphoton excess at the LHC could be the first hint of a superbump signature.

   hep-phhep-thJHEP(2016)·2 citations
4. 04*

   Parton Distribution Function from the Hadronic Tensor on the Lattice

   Keh-Fei Liu🇺🇸

   The path-integral formulation of the hadronic tensor W_{\mu\nu} of deep inelastic scattering is reviewed. It is shown that there are 3 gauge invariant and topologically distinct contributions. The separation of the connected sea partons from those of the disconnected sea can be achieved with a combination of the global fit of the parton distribution function (PDF), the semi-inclusive DIS data on the strange PDF and the lattice calculation of the ratio of the strange to $u/d$ momentum fraction in the disconnected insertion. We shall discuss numerical issues associated with lattice calculation of the hadronic tensor involving a four-point function, such as large hadron momenta and improved maximum entropy method to obtain the spectral density from the hadronic tensor in Euclidean time. We also draw a comparison between the large momentum approach to the parton distribution function (PDF) and the hadronic tensor approach.

   hep-phhep-latnucl-thPoS(2016)·40 citations
5. 05*

   Photon-jet ridge at RHIC and the LHC

   Amir H. Rezaeian🇨🇱

   We investigate long range rapidity correlations of pairs of prompt photon and jet in the Color Glass Condensate (CGC) framework in proton-proton and proton-nucleus collisions at RHIC and the LHC. We show that photon-jet correlations exhibit long-range azimuthal collimation at near-side for low transverse momenta of the produced photon and jet in high-multiplicity events. These ridge-like features are strikingly similar to the observed ridge effect for di-hadron correlations at RHIC and the LHC. We show that correlations in the relative rapidity and the relative azimuthal angle between pairs of prompt photon and jet strongly depend on the gluon saturation dynamics at small-x kinematics and such measurements can help to understand the true origin of the observed di-hadron ridge in p+A collisions, and address whether the ridge is a universal phenomenon for all two particle correlations at high energy and high multiplicity events. We also investigate if there is a ridge-like structure for photon-hadron pair correlations at RHIC and the LHC. We found that the hadronization of jet has non-trivial effects on the photon-jet correlations.

   hep-phhep-exPRD(2016)·24 citations
6. 06*

   WIMP Dark Matter in a Well-Tempered Regime: A case study on Singlet-Doublets Fermionic WIMP

   Shankha Banerjee🇫🇷 · Shigeki Matsumoto🇯🇵 · Kyohei Mukaida🇯🇵 · Yue-Lin Sming Tsai🇯🇵

   Serious searches for the weakly interacting massive particle (WIMP) have now begun. In this context, the most important questions that need to be addressed are: "To what extent can we constrain the WIMP models in the future?" and "What will then be the remaining unexplored regions in the WIMP parameter space for each of these models?" In our quest to answer these questions, we classify WIMP in terms of quantum number and study each case adopting minimality as a guiding principle. As a first step, we study one of the simple cases of the minimal composition in the well-tempered fermionic WIMP regime, namely the singlet-doublets WIMP model. We consider all available constraints from direct and indirect searches and also the predicted constraints coming from the near future and the future experiments. We thus obtain the current status, the near future prospects and the future prospects of this model in all its generality. We find that in the future, this model will be constrained almost solely by the future direct dark matter detection experiments (as compared to the weaker indirect and collider constraints) and the cosmological (relic density) constraints and will hence be gradually pushed to the corner of the coannihilation region, if no WIMP signal is detected. Future lepton colliders will then be useful in exploring this region not constrained by any other experiments.

   hep-phJHEP(2016)·87 citations
7. 07*

   The evolution of the small x gluon TMD

   Jian Zhou🇨🇳

   We study the evolution of the small $x$ gluon transverse momentum dependent(TMD) distribution in the dilute limit. The calculation has been carried out in the Ji-Ma-Yuan scheme using a simple quark target model. As expected, we find that the resulting small $x$ gluon TMD simultaneously satisfies both the Collins-Soper(CS) evolution equation and the Balitsky-Fadin-Kuraev-Lipatov(BFKL) evolution equation. We thus confirmed the earlier finding that the high energy factorization(HEF) and the TMD factorization should be jointly employed to resum the different type large logarithms in a process where three relevant scales are well separated.

   hep-phJHEP(2016)·28 citations
8. 08*

   Non-Hermitian $\mathcal{P}\mathcal{T}$-symmetric relativistic quantum theory in an intensive magnetic field

   V.N. Rodionov🇷🇺

   We develop relativistic non-Hermitian quantum theory and its application to neutrino physics in a strong magnetic field. It is well known, that one of the fundamental postulates of quantum theory is the requirement of Hermiticity of physical parameters. This condition not only guarantees the reality of the eigenvalues of Hamiltonian operators, but also implies the preservation of the probabilities of the considered quantum processes. However as it was shown relatively recently (Bender, Boettcher 1998), Hermiticity is a sufficient but it is not a necessary condition. It turned out that among non-Hermitian Hamiltonians it is possible to allocate a number of such which have real energy spectra and can ensure the development of systems over time with preserving unitarity. This type of Hamiltonians includes so-called parity-time ($\mathcal{P}\mathcal{T}$) symmetric models which is already used in various fields of modern physics. The most developed in this respect are models, which used in the field of $\mathcal{P}\mathcal{T}$-symmetric optics, where for several years produced not only theoretical but experimental studies.

   hep-phastro-ph.HEhep-exSpringer Proc.Phys.(2016)·1 citation
9. 09*

   Some uncertainties of neutrino oscillation effect in the NO$\nu$A experiment

   Lyudmila D. Kolupaeva (1 and 2)🇷🇺 · Konstantin S. Kuzmin (1 and 3)🇷🇺 · Olga N. Petrova (2)🇷🇺 · Igor M. Shandrov (2) ((1) Dubna, JINR, (2) Moscow State U., (3) Moscow, ITEP)🇷🇺

   Uncertainties related to the effect of neutrino coherent forward scattering in Earth's matter (MSW mechanism) and with the cross sections of quasi-elastic neutrino scattering on nuclear targets of the NO$\nu$A detectors are studied. The NO$\nu$A sensitivity to the neutrino mass hierarchy and the CP violating phase is discussed.

   hep-phMod.Phys.Lett.A(2016)·7 citations
10. 10*

    The mixing angle as a function of neutrino mass ratio

    Subhankar Roy🇮🇳 · N.Nimai Singh🇮🇳

    In the quark sector, we experience a correlation between the mixing angles and the mass ratios. A partial realization of the similar tie-up in the neutrino sector helps to constrain the parametrization of masses and mixing, and hints for a predictive framework. We derive five hierarchy dependent textures of neutrino mass matrix with minimum number of parameters ($\le 4$), following a model-independent strategy.

    hep-phPRD(2015)·3 citations
11. 11*

    $B_{s,d}^0\to l^{+}{l}^{-}$ in the minimal gauged $(B-L)$ supersymmetry

    Tai-Fu Feng🇨🇳 · Yu-Li Yan🇨🇳 · Hai-Bin Zhang🇨🇳 · Shu-Min Zhao🇨🇳

    Complete expressions of effective Hamilton for $b\to s{l}^{+}{l}^{-}(l=\mu ,\tau )$ are derived in the framework of minimal supersymmetric extension of the standard model with local $B-L$ gauge symmetry. With some assumptions on parameters of the model, a numerical analysis of the supersymmetric contributions to the branching ratios of $B_s^0\to l^{+}{l}^{-}(l=\mu ,\tau )$ is presented.

    hep-phInt.J.Mod.Phys.A(2016)·5 citations
12. 12*

    Renormalization Group Improved Higgs Inflation with a Running Kinetic Term

    Fuminobu Takahashi🇯🇵 · Ryo Takahashi🇯🇵

    We study a Higgs inflation model with a running kinetic term, taking account of the renormalization group evolution of relevant coupling constants. Specifically we study two types of the running kinetic Higgs inflation, where the inflaton potential is given by the quadratic or linear term potential in a frame where the Higgs field is canonically normalized. We solve the renormalization group equations at two-loop level and calculate the scalar spectral index and the tensor-to-scalar ratio. We find that, even if the renormalization group effects are included, the quadratic inflation is ruled out by the CMB observations, while the linear one is still allowed.

    hep-phastro-ph.COhep-exPLB(2016)·3 citations
13. 13*

    Hybridized Tetraquarks

    A. Esposito🇺🇸 · A. Pilloni🇺🇸 · A.D. Polosa🇮🇹

    We propose a new interpretation of the neutral and charged X, Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules. The latter would require a negative or zero binding energy whose counterpart in h-tetraquarks is a positive quantity. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs pi+- channel by the D0 collaboration and the negative result presented subsequently by the LHCb collaboration are understood in this scheme, together with a considerable portion of available data on X, Z particles. Considerations on a state with the same quantum numbers as the X(5568) are also made.

    hep-phPLB(2016)·67 citations
14. 14*

    Leptoquark patterns unifying neutrino masses, flavor anomalies, and the diphoton excess

    F. F. Deppisch🇬🇧 · S. Kulkarni🇦🇹 · H. Päs🇩🇪 · E. Schumacher🇩🇪

    Vector leptoquarks provide an elegant solution to a series of anomalies and at the same time generate naturally light neutrino masses through their mixing with the standard model Higgs boson. We present a simple Froggatt-Nielsen model to accommodate the B physics anomalies $R_K$ and $R_D$, neutrino masses, and the $750$ GeV diphoton excess in one cohesive framework adding only two vector leptoquarks and two singlet scalar fields to the standard model field content.

    hep-phPRD(2016)·64 citations
15. 15*

    Simulations of Galaxy Cluster Collisions with a Dark Plasma Component

    Christian Spethmann🇪🇪 · Hardi Veermäe🇪🇪 · Tiit Sepp🇪🇪 · Matti Heikinheimo🇫🇮 · Boris Deshev🇪🇪 · Andi Hektor🇪🇪 · Martti Raidal🇪🇪

    Dark plasma is an intriguing form of self-interacting dark matter with an effective fluid-like behavior, which is well motivated by various theoretical particle physics models. We aim to find an explanation for an isolated mass clump in the Abell 520 system, which cannot be explained by traditional models of dark matter, but has been detected in weak lensing observations. We performed N-body smoothed particle hydrodynamics simulations of galaxy cluster collisions with a two component model of dark matter, which is assumed to consist of a predominant non-interacting dark matter component and a 10-40 percent mass fraction of dark plasma. The mass of a possible dark clump was calculated for each simulation in a parameter scan over the underlying model parameters. In two higher resolution simulations shock-waves and Mach cones were observed to form in the dark plasma halos. By choosing suitable simulation parameters, the observed distributions of dark matter in both the Bullet Cluster (1E 0657-558) and Abell 520 (MS 0451.5+0250) can be qualitatively reproduced.

    ↳ astro-ph.COhep-phAstron.Astrophys.(2017)·27 citations
16. 16*

    Dark energy from gravitational corrections

    Yugo Abe🇯🇵 · Masaatsu Horikoshi🇯🇵 · Yoshiharu Kawamura🇯🇵

    We study physics concerning the cosmological constant problem in the framework of effective field theory and suggest that a dominant part of dark energy can originate from gravitational corrections of vacuum energy, under the assumption that the classical gravitational fields do not couple to a large portion of the vacuum energy effectively, in spite of the coupling between graviton and matters at a microscopic level. Our speculation is excellent with terascale supersymmetry.

    ↳ hep-thastro-ph.COgr-qchep-phInt.J.Mod.Phys.A(2017)·2 citations
17. 17*

    Strange Quark Stars as Probe of Dark Matter

    Hao Zheng🇨🇳 · Lie-Wen Chen🇨🇳

    We demonstrate that the observation of old strange quark stars (SQSs) can set important limits on the scattering cross sections ${\sigma }_q$ between the light quarks and the non-interacting scalar dark matter (DM). By analyzing a set of 1403 of solitary pulsarlike compact stars in the Milky Way, we find the old solitary pulsar PSR J1801-0857D can set the most stringent upper limits on ${\sigma }_q$ or the DM-proton scattering cross sections ${\sigma }_p$. By converting ${\sigma }_q$ into ${\sigma }_p$ based on effective operator analyses, we show the resulting ${\sigma }_p$ limit by assuming PSR J1801-0857D to be a SQS could be comparable with that of the current direct detection experiments but much weaker (by several orders of magnitude) than that obtained by assuming PSR J1801-0857D to be a neutron star (NS), which requires an extremely small ${\sigma }_p$ far beyond the limits of direct detection experiments. Our findings imply that the old pulsars are favored to be SQSs rather than NSs if the scalar DM were observed by future terrestrial experiments.

    ↳ nucl-thastro-ph.COastro-ph.SRhep-ph+1ApJ(2016)·20 citations
18. 18*

    The quenched SU(2) fundamental 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. As the analytic structure plays an important role in this question, high-precision data is necessary for lattice investigations. Also, it is interesting how this depends on the dimensionality of the theory. To make a study over a wide range of parameters possible this suggests to use scalar particles. This is done here: The propagator of a fundamental scalar is studied in two, three, and four dimensions in quenched SU(2) Yang-Mills theory in minimal Landau gauge, both in momentum space and position space. Particular emphasis is put on the effects of renormalization. The results suggest a quite intricate volume dependence and the presence of an intrinsic mass scale, but no obvious connection to confinement.

    ↳ hep-lathep-phEPJC(2016)·7 citations
19. 19*

    Can we obtain a "new femtoscopy" on the basis of electromagnetic effects?

    Andrzej Rybicki🇵🇱 · Antoni Szczurek🇵🇱 · Miroslaw Kielbowicz🇵🇱 · Nikolaos Davis🇵🇱 · Vitalii Ozvenchuk🇵🇱

    We review our studies of spectator-induced electromagnetic (EM) effects on charged pion emission in ultrarelativistic heavy ion collisions. These effects are found to consist in the electromagnetic {charge splitting} of pion directed flow as well as very large distortions in spectra and ratios of produced charged particles. As it emerges from our analysis, they offer sensitivity to the actual distance $d_E$ between the pion formation zone at freeze-out and the spectator matter. As a result, this gives a new possibility of studying the space-time evolution of dense and hot matter created in the course of the collision. Having established that $d_E$ traces the longitudinal evolution of the system and therefore rapidly decreases as a function of pion rapidity, we investigate the latter finding in view of pion feed-over from intermediate resonance production. As a result we obtain a first estimate of the pion decoupling time from EM effects which we compare to existing HBT data. We conclude that spectator-induced EM interactions can serve as a new tool for studying the space-time characteristics and longitudinal evolution of the system.

    ↳ nucl-thhep-exhep-phActa Phys.Polon.Supp.(2016)·10 citations
20. 20*

    Limits on the Neutrino Velocity, Lorentz Invariance, and the Weak Equivalence Principle with TeV Neutrinos from Gamma-Ray Bursts

    Jun-Jie Wei🇨🇳 · Xue-Feng Wu🇨🇳 · He Gao🇨🇳 · Peter Mészáros🇺🇸

    Five TeV neutrino events weakly correlated with five gamma-ray bursts (GRBs) were detected recently by IceCube. This work is an attempt to show that if the GRB identifications are verified, the observed time delays between the TeV neutrinos and gamma-ray photons from GRBs provide attractive candidates for testing fundamental physics with high accuracy. Based on the assumed associations between the TeV neutrinos and GRBs, we find that the limiting velocity of the neutrinos is equal to that of photons to an accuracy of $\sim 1.9\times 10^{-15}-2.5\times 10^{-18}$, which is about $10^4-10^7$ times better than the constraint obtained with the neutrino possibly from a blazar flare. In addition, we set the most stringent limits up to date on the energy scale of quantum gravity for both the linear and quadratic violations of Lorentz invariance, namely $E_{\mathrm{QG},1}>6.3\times 10^{18}-1.5\times 10^{21}$ GeV and $E_{\mathrm{QG},2}>2.0\times 10^{11}-4.2\times 10^{12}$ GeV, which are essentially as good as or are an improvement of one order of magnitude over the results previously obtained by the GeV photons of GRB 090510 and the PeV neutrino from a blazar flare. Assuming that the Shapiro time delay is caused by the gravitational potential of the Laniakea supercluster of galaxies, we also place the tightest limits to date on Einstein's weak equivalence principle through the relative differential variations of the parameterized post-Newtonian parameter $\gamma$ values for two different species of particles (i.e., neutrinos and photons), yielding $\Delta \gamma \sim 10^{-11}-10^{-13}$. However, it should be emphasized again that these limits here obtained are at best forecast of what could be achieved if the GRB/neutrino correlations would be finally confirmed.

    ↳ astro-ph.HEgr-qchep-phJCAP(2016)·40 citations
21. 21*

    Observational signatures of Higgs inflation

    Vera-Maria Enckell🇫🇮 · Kari Enqvist🇫🇮 · Sami Nurmi🇫🇮

    We investigate the dependency of Higgs inflation on the non-renormalisable matching between the low energy Standard Model limit and the inflationary regime at high energies. We show that for the top mass range $m_t\gtrsim 171.8$ GeV the scenario robustly predicts the spectral index $n_s\simeq 0.97$ and the tensor-to-scalar ratio $r\simeq 0.003$. The matching is however non-trivial, even the best-fit values $m_h=125.09$ GeV and $m_t=173.21$ GeV require a jump $\delta \lambda \sim 0.01$ in the Higgs coupling below the inflationary scale. For $m_t\lesssim 171.8$ GeV, the matching may generate a feature in the inflationary potential. In this case the predicted values of $n_s$ and $r$ vary but the model is still falsifiable. For example, a detection of negative running of spectral index at level ${\alpha }_s\lesssim -0.01$ would rule out Higgs inflation.

    ↳ astro-ph.COhep-phJCAP(2016)·40 citations
22. 22*

    Composite gauge-bosons made of fermions

    Mahiko Suzuki🇺🇸

    We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is compact and local without containing an auxiliary vector field nor a subsidiary condition on the matter fields. Because of the special structure, this Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out explicit dynamical computation in the leading 1/N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be explored in the formal auxiliary vector-field trick. For instance, it shows that the s-wave fermion-antifermion interaction alone cannot form the bound gauge-bosons; the fermion-antifermion pairs must couple to the d-wave state too. One feature common to our class of Lagrangian is that the Noether current does not exist. Therefore it evades possible conflict with the no-go theorem of Weinberg and Witten on formation of the non-Abelian gauge bosons.

    ↳ hep-thhep-phPRD(2016)·10 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.