Mon·Aug 22, 2016Monday·August 22, 2016

1. 01*

   Transverse spin observables in hard-scattering hadronic processes within collinear factorization

   D. Pitonyak🇺🇸

   We review what is currently known about the transverse spin structure of hadrons, in particular from observables that can be analyzed within a collinear framework. These effects have been around for 40 years and represent a critical test of perturbative QCD. We look at both proton-proton and lepton-nucleon collisions for various final states. While the main focus is on transverse single-spin asymmetries, we also discuss how longitudinal-transverse double-spin asymmetries offer a complimentary, yet equally important, source of information on the quark-gluon content of hadrons. We also summarize some recent progress in solidifying the theoretical formalism behind these observables and give an outlook on future directions of research.

   hep-phhep-exInt.J.Mod.Phys.A(2016)·21 citations
2. 02*

   The Super-GUT CMSSM Revisited

   John Ellis🇬🇧 · Jason L. Evans🇰🇷 · Azar Mustafayev🇺🇸 · Natsumi Nagata🇺🇸 · Keith A. Olive🇺🇸

   We revisit minimal supersymmetric SU(5) grand unification (GUT) models in which the soft supersymmetry-breaking parameters of the minimal supersymmetric Standard Model (MSSM) are universal at some input scale, $M_{in}$, above the supersymmetric gauge coupling unification scale, $M_{GUT}$. As in the constrained MSSM (CMSSM), we assume that the scalar masses and gaugino masses have common values, $m_0$ and $m_{1/2}$ respectively, at $M_{in}$, as do the trilinear soft supersymmetry-breaking parameters $A_0$. Going beyond previous studies of such a super-GUT CMSSM scenario, we explore the constraints imposed by the lower limit on the proton lifetime and the LHC measurement of the Higgs mass, $m_h$. We find regions of $m_0$, $m_{1/2}$, $A_0$ and the parameters of the SU(5) superpotential that are compatible with these and other phenomenological constraints such as the density of cold dark matter, which we assume to be provided by the lightest neutralino. Typically, these allowed regions appear for $m_0$ and $m_{1/2}$ in the multi-TeV region, for suitable values of the unknown SU(5) GUT-scale phases and superpotential couplings, and with the ratio of supersymmetric Higgs vacuum expectation values $\tan \beta \lesssim 6$.

   hep-phEPJC(2016)·52 citations
3. 03*

   Analysing parameter space correlations of recent 13 TeV gluino and squark searches in the pMSSM

   Alan Barr🇬🇧 · Jesse Liu🇬🇧

   This paper examines unexplored correlations in the parameter spaces probed by recent ATLAS analyses for gluinos and squarks, addressing various shortcomings in the literature. Six 13 TeV ATLAS analyses based on 3.2 fb${}^{-1}$ of integrated luminosity are interpreted in the 19-parameter R-parity conserving phenomenological minimal supersymmetric extension to the Standard Model (pMSSM). The distinct regions covered by each search are independent of prior, and we reveal particularly striking complementarity between the 2-6 jets and Multi-b searches. In the leptonic searches, we identify better sensitivity to models than those used for analysis optimisation, notably a squark-slepton-wino scenario for the SS/3L search. Further, we show how collider searches for coloured states probe the structure of the pMSSM dark sector more extensively than the Monojet analysis alone, with sensitivity to parameter spaces that are challenging for direct detection experiments.

   hep-phhep-exEPJC(2017)·16 citations
4. 04*

   Mott dissociation of pions and kaons in hot, dense quark matter

   A. Dubinin🇵🇱 · A. Radzhabov🇷🇺 · D. Blaschke🇷🇺 · A. Wergieluk🇺🇸

   We describe the Mott dissociation of pions and kaons within a Beth-Uhlenbeck approach based on the PNJL model, which allows for a unified description of bound, resonant and scattering states. Within this model we evaluate the temperature and chemical potential dependent modification of the phase shifts both in the pseudoscalar and scalar isovector meson channels for $N_f=2+1$ quark flavors. We show that the character change of the pseudoscalar bound states to resonances in the continuum at the Mott transition temperature is signaled by a jump of the phase shift at the threshold from $\pi$ to zero, in accordance with the Levinson theorem. In particular, we demonstrate the importance of accounting for the scattering continuum states, which ensures that the total phase shift in each of the meson channels vanishes at high energies, thus eliminating mesonic correlations from the thermodynamics at high temperatures. In this way, we prove that the present approach provides a unified description of the transition from a meson gas to a quark-gluon plasma. We discuss the occurrence of an anomalous mode for mesons composed of quarks with unequal masses which is particularly pronounced for $K^{+}$ and ${\kappa }^{+}$ states at finite densities a a possible mechanism to explain the "horn" effect for the $K^{+}/{\pi }^{+}$ ratio in heavy-ion collisions.

   hep-phnucl-thPRD(2017)·33 citations
5. 05*

   Unifying inflation with the axion, dark matter, baryogenesis and the seesaw mechanism

   Guillermo Ballesteros🇫🇷 · Javier Redondo🇪🇸 · Andreas Ringwald🇩🇪 · Carlos Tamarit🇬🇧

   A minimal extension of the Standard Model (SM) with a single new mass scale and providing a complete and consistent picture of particle physics and cosmology up to the Planck scale is presented. We add to the SM three right-handed SM-singlet neutrinos, a new vector-like color triplet fermion and a complex SM singlet scalar $\sigma$ that stabilises the Higgs potential and whose vacuum expectation value at $\sim 10^{11}$ GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously. Primordial inflation is produced by a combination of $\sigma$ (non-minimally coupled to the scalar curvature) and the SM Higgs. Baryogenesis proceeds via thermal leptogenesis. At low energies, the model reduces to the SM, augmented by seesaw-generated neutrino masses, plus the axion, which solves the strong CP problem and accounts for the dark matter in the Universe. The model predicts a minimum value of the tensor-to-scalar ratio $r\simeq 0.004$, running of the scalar spectral index $\alpha \simeq -7\times 10^{-4}$, the axion mass $m_A\sim 100\mu \mathrm{eV}$ and cosmic axion background radiation corresponding to an increase of the effective number of relativistic neutrinos of $\sim 0.03$. It can be probed decisively by the next generation of cosmic microwave background and axion dark matter experiments.

   hep-phastro-ph.COhep-thPRL(2017)·210 citations
6. 06*

   The new interaction suggested by the anomalous ${}^8$Be transition sets a rigorous constraint on the mass range of dark matter

   Lian-Bao Jia🇨🇳 · Xue-Qian Li🇨🇳

   The WIMPs are considered one of the favorable dark matter (DM) candidates, but as the upper bounds on the interactions between DM and standard model (SM) particles obtained by the upgraded facilities of DM direct detections get lower and lower. Researchers turn their attentions to search for less massive DM candidates, i.e. light dark matter of MeV scale. The recently measured anomalous transition in ${}^8$Be suggests that there exists a vectorial boson which may mediate the interaction between DM and SM particles. Based on this scenario, we combine the relevant cosmological data to constrain the mass range of DM, and have found that there exists a model parameter space where the requirements are satisfied, a range of $10.4\lesssim m_{\varphi }\lesssim$ 16.7 MeV for scalar DM, and $13.6\lesssim m_V\lesssim$ 16.7 MeV for vectorial DM is demanded. Then a possibility of directly detecting such light DM particles via the DM-electron scattering is briefly studied in this framework.

   hep-phastro-ph.COEPJC(2016)·36 citations
7. 07*

   Bound muon decay spectrum in the leading logarithmic accuracy

   Robert Szafron🇨🇦 · Andrzej Czarnecki🇨🇦

   We compute the dominant, logarithmically enhanced radiative corrections to the electron spectrum in the bound muon decay in the whole experimentally interesting range. The corrected spectrum fits well the TWIST results. The remaining theoretical error, dominated by the nuclear charge distribution, can be reduced in the muon-electron conversion searches by measuring the spectrum slightly below the New Physics signal window.

   hep-phPRD(2016)·22 citations
8. 08*

   The hidden charm pentaquarks are the hidden color-octet $uud$ baryons?

   Sachiko Takeuchi🇯🇵 · Makoto Takizawa🇯🇵

   The $I(J^P)=\frac{1}{2}({\frac{1}{2}}^{-})$, $\frac{1}{2}({\frac{3}{2}}^{-})$, and $\frac{1}{2}({\frac{5}{2}}^{-})$ $uudc\overline{c}$ pentaquarks are investigated by the quark cluster model. This model, which reproduces the mass spectra of the color-singlet $S$-wave $q^3$ baryons and $q\overline{q}$ mesons, also enables us to evaluate the quark interaction in the color-octet $uud$ configurations. It is shown that the color-octet isospin-$\frac{1}{2}$ spin-$\frac{3}{2}$ $uud$ configuration gains attraction. The $uudc\overline{c}$ states with this configuration have structures around the ${\Sigma }_c{}^{(\ast )}\overline{D}{}^{(\ast )}$ thresholds: one bound state, two resonances, and one large cusp are found. We argue that the negative parity pentaquark found by the LHCb experiments may be given by these structures.

   hep-phPLB(2017)·58 citations
9. 09*

   Gauge Symmetry Breaking Patterns in an SU(5) Grand Gauge-Higgs Unification

   Kentaro Kojima🇯🇵 · Kazunori Takenaga🇯🇵 · Toshifumi Yamashita🇯🇵

   We study gauge symmetry breaking patterns of the five-dimensional $SU(5)$ grand gauge-Higgs unification compactified on an orbifold $S^1/{\mathbb{Z}}_2$ with the Hosotani mechanism in the framework of the diagonal embedding method. We find matter contents that lead to the $SU(3)\times SU(2)\times U(1)$ gauge symmetry on the global minimum of the effective potential and also present examples of matter content for which each regular subgroup of $SU(5)$ is realized as vacuum configuration. The finite temperature phase transitions for the models with the gauge symmetry of the standard model at zero temperature and also for supersymmetric models are studied. We show in a certain model with supersymmetry that the vacuum of the standard model selected dynamically before the inflation continues to stay there up to the present.

   hep-phPRD(2017)·39 citations
10. 10*

    Charged Lepton Flavor Violating Processes and Scalar Leptoquark Decay Branching Ratios in the Colored Zee-Babu Model

    We-Fu Chang🇹🇼 · Siao-Cing Liou🇹🇼 · Chi-Fong Wong🇨🇳 · Fanrong Xu🇨🇳

    We consider a neutrino mass generating model which employs a scalar leptoquark, $\Delta$, and a scalar diquark, $S$. The new scalars $\Delta$ and $S$ carry the standard model $SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y$ quantum numbers $(3,1,-1/3)$ and $(6,1,-2/3)$, respectively. The neutrino masses are generated at the two-loop level, as in the Zee-Babu model\cite{Zee-Babu}, and $\Delta /S$ plays the role of the doubly/singly charged scalar in the Zee-Babu model. With a moderate working assumption that the magnitudes of the six Yukawa couplings between $S$ and the down-type quarks are of the same order, strong connections are found between the neutrino masses and the charged lepton flavor violating processes. In particular, we study $Z\to \overline{l}{l}^{\prime }$, and $l\to l^{\prime }\gamma$ and find that some portions of the parameter space of this model are within the reach of the planned charged lepton flavor violating experiments. Interesting lower bounds are predicted that $B(Z\to \overline{l}{l}^{\prime })\gtrsim 10^{-16}-10^{-14}(10^{-14})\times (1\text{mbox}TeV\cdot m_S/7m_{\Delta }^2{)}^2$ and $B(l\to l^{\prime }\gamma )\gtrsim 10^{-17}-10^{-16}(10^{-18}-10^{-16})\times (1\text{mbox}TeV\cdot m_S/7m_{\Delta }^2{)}^2$ for neutrino masses being the normal(inverted) hierarchical pattern. The type of neutrino mass hierarchy could also be determined by measuring the charged lepton flavor violating double ratios. Moreover, definite leptoquark decay branching ratios are predicted when there is no Yukawa interaction between the right-handed fermions and $\Delta$ ( the branching fraction of $\Delta$ to a charged lepton and a quark is 50\%), which could help refine the collider search limit on the scalar leptoquark mass.

    hep-phJHEP(2016)·20 citations
11. 11*

    Neutrino induced vorticity, Alfven waves and the normal modes

    Jitesh R. Bhatt🇮🇳 · Manu George🇮🇳

    We consider plasma consisting of electrons and ions in presence of a background neutrino gas and develop the magneto hydrodynamic equations for the system. We show that electron neutrino interaction can induce vorticity in the plasma even in the absence of any electromagnetic perturbations if the background neutrino density is left-right asymmetric. This induced vorticity support a new kind of Alfvén wave whose velocity depends on both the external magnetic field and on the neutrino asymmetry. The normal mode analysis show that in the presence of neutrino background the Alfvén waves can have different velocities. We also discuss our results in the context of dense astrophysical plasma such as magnetars and show that the difference in the Alfvén velocities can be used to explain the observed pulsar kick. We discuss also the relativistic generalization of electron fluid in presence of asymmetric neutrino background.

    hep-phEPJC(2017)·5 citations
12. 12*

    Strong coupling constant of negative parity nucleon with $\pi$ meson in light cone QCD sum rules

    T. M. Aliev (1)🇹🇷 · T. Barakat (2)🇸🇦 · M. Savcı (1) ((1) Middle East Technical University/Ankara/Turkey, (2) King Saud University/Riyadh/Saudi Arabia)🇹🇷

    We estimate strong coupling constant between the negative parity nucleons with $\pi$ meson within the light cone QCD sum rules. A method for eliminating the unwanted contributions coming from the nucleon--nucleon and nucleon--negative parity nucleon transition is presented. It is observed that the value strong coupling constant of the negative parity nucleon $N^{\ast }{N}^{\ast }\pi$ transition is considerably different from the one predicted by the 3--point QCD sum rules, but is quite close to the coupling constant of the positive parity $NN\pi$ transition.

    hep-phPRC(2017)·6 citations
13. 13*

    Exploring the extended scalar sector with resonances in vector boson scattering

    Najimuddin Khan🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Subhendu Rakshit🇮🇳 · Avirup Shaw🇮🇳

    We show that the study of scalar resonances at various vector boson scattering processes at the Large Hadron Collider can serve as a useful tool to distinguish between different extensions of the scalar sector of the Standard Model. The recent measurement of the Higgs boson properties leaves enough room for the extended scalar sectors to be relevant for such studies. The shape of the resonances, being model dependent, can shed light on the viable parameter space of a number of theoretical models.

    hep-ph3 citations
14. 14*

    Diffractive di-jet production at the LHC with a Reggeon contribution

    C. Marquet🇫🇷 · D.E. Martins🇧🇷 · A.V. Pereira🇧🇷 · M. Rangel🇧🇷 · C. Royon🇺🇸

    We study hard diffractive scattering in hadron-hadron collisions including, on top of the standard Pomeron-initiated processes, contributions due to the exchange of Reggeons. Using a simple model to describe the parton content of the Reggeon, we compute di-jet production in single diffractive and central diffractive events. We show that Reggeon contributions can be sizable at the LHC, and even sometimes dominant, and we identify kinematic windows in which they could be experimentally studied. We argue that suitable measurements must be performed in order to properly constrain the model, and be able to correctly account for Reggeon exchanges in the analysis of the many hard diffractive observables to be measured at the LHC.

    hep-phPLB(2017)·13 citations
15. 15*

    Finite temperature corrections to a NLO Nambu-Jona-Lasinio model

    Marco Frasca🇮🇹

    We derive the next-to-leading order correction to the Nambu-Jona-Lasinio model starting from quantum chromodynamics. So, we are able to fix the constants of the Nambu-Jona-Lasinio model from quantum chromodynamics and analyze the behavior of strong interactions at low energies. The technique is to expand in powers of currents the generating functional. We apply it to a simple Yukawa model with self-interaction showing how this has a Nambu-Jona-Lasinio model and its higher order corrections as a low-energy limit. The same is shown to happen for quantum chromodynamics in the chiral limit with two quarks. We prove that a consistent thermodynamic behaviour is obtained as expected for the given parameters.

    hep-phNucl.Part.Phys.Proc.(2017)·2 citations
16. 16*

    Algorithms to solve coupled systems of differential equations in terms of power series

    Jakob Ablinger🇦🇹 · Arnd Behring🇩🇪 · Johannes Bluemlein · Abilio de Freitas🇩🇪 · Carsten Schneider🇦🇹

    Using integration by parts relations, Feynman integrals can be represented in terms of coupled systems of differential equations. In the following we suppose that the unknown Feynman integrals can be given in power series representations, and that sufficiently many initial values of the integrals are given. Then there exist algorithms that decide constructively if the coefficients of their power series representations can be given within the class of nested sums over hypergeometric products. In this article we will work out the calculation steps that solve this problem. First, we will present a successful tactic that has been applied recently to challenging problems coming from massive 3-loop Feynman integrals. Here our main tool is to solve scalar linear recurrences within the class of nested sums over hypergeometric products. Second, we will present a new variation of this tactic which relies on more involved summation technologies but succeeds in reducing the problem to solve scalar recurrences with lower recurrence orders. The article will work out the different challenges of this new tactic and demonstrates how they can be treated efficiently with our existing summation technologies.

    ↳ cs.SChep-phmath-phmath.MPPoS(2016)·13 citations
17. 17*

    Rapidity Correlation Structures from Causal Hydrodynamics

    Sean Gavin🇺🇸 · George Moschelli🇺🇸 · Christopher Zin🇺🇸

    Viscous diffusion can broaden the rapidity dependence of two-particle transverse momentum fluctuations. Surprisingly, measurements at RHIC by the STAR collaboration demonstrate that this broadening is accompanied by the appearance of unanticipated structure in the rapidity distribution of these fluctuations in the most central collisions. Although a first order classical Navier-Stokes theory can roughly explain the rapidity broadening, it cannot explain the additional structure. We propose that the rapidity structure can be explained using the second order causal Israel-Stewart hydrodynamics with stochastic noise.

    ↳ nucl-thhep-phJ.Phys.Conf.Ser.(2016)·5 citations
18. 18*

    Guido Altarelli and the evolution of QCD

    R. Keith Ellis🇬🇧

    I describe the contributions of Guido Altarelli to the development of Quantum Chromodynamics from the discovery of asymptotic freedom until the end of the S$p\bar{p}$S collider era, 1973-1985.

    ↳ physics.hist-phhep-ph0 citations
19. 19*

    Formation of hypernuclei in heavy-ion collisions around the threshold energies

    A.S. Botvina (Frankfurt U., FIAS, ITP & Moscow, INR)🇩🇪 · K.K. Gudima (Kishinev, IAP)🇲🇩 · J. Steinheimer (Frankfurt U., FIAS)🇩🇪 · M. Bleicher (Frankfurt U., FIAS, ITP)🇩🇪 · J. Pochodzalla (Mainz U., HIM, IKP)🇩🇪

    In relativistic ion collisions there are excellent opportunities to produce and investigate hyper-nuclei. We have systematically studied the formation of hypernuclear spectator residues in peripheral heavy-ion collisions with the transport DCM and UrQMD models. The hyperon capture was calculated within the potential and coalescence approaches. We demonstrate that even at the beam energies around and lower than the threshold for producing Lambda hyperons in binary nucleon-nucleon interactions a considerable amount of hypernuclei, including multi-strange ones, can be produced. This is important for preparation of new experiments on hypernuclei in the wide energy range. The uncertainties of the predictions are investigated within the models, and the comparison with the strangeness production measured in experiments is also performed.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2017)·43 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.